ARTIGOS CIENTÍFICOS
2020
Sara Resende, MF Frasco, M. Goreti F. Sales A biomimetic photonic crystal sensor for label-free detection of urinary venous thromboembolism biomarker (Journal Article) Sensors and Actuators B: Chemical, pp. 127947, 2020. @article{Resende.2019, title = {A biomimetic photonic crystal sensor for label-free detection of urinary venous thromboembolism biomarker}, author = {Sara Resende and MF Frasco and M. Goreti F. Sales }, url = {https://doi.org/10.1016/j.snb.2020.127947}, doi = {10.1016/j.snb.2020.127947}, year = {2020}, date = {2020-03-04}, journal = {Sensors and Actuators B: Chemical}, pages = {127947}, abstract = {This work reports a novel label-free sensor combining photonic crystals and molecularly-imprinted polymer materials for targeting a protein in human samples within levels of clinical interest. This concept was applied to detect fibrinopeptide B (FPB) in urine, a biomarker of venous thromboembolism, which is a disease of great concern and demands innovative point-of-care devices for improved diagnosis. The molecularly-imprinted photonic polymer (MIPP) was obtained by tailoring an imprinted polymer on highly ordered silica nanoparticles assembled by vertical deposition. Owing to the hierarchical structure, the resulting MIPP exhibited optical properties that changed upon rebinding of the target analyte, FPB. Thus, the changes in reflectance intensity enabled a rapid and sensitive detection of FPB in human urine. The observed response was linear between 0.2 ng mL-1 and 22 ng mL-1 and showed a limit of detection of 0.13 ng mL-1. These features of the sensing material allow the assessment of urinary FPB at relevant clinical levels. In addition, the sensor was selective for FPB compared to the standard biomarker of venous thromboembolism, D-Dimer. The stability of the material was evidenced by the reusability study, which demonstrated reversibility of the maximum intensity after three cycles of recognition and regeneration. Moreover, the sensor showed good performance for the spiked FPB detection in control human urine. Overall, the application of such label-free sensor offers high selectivity and stability, as well as easy operation. It may constitute an alternative method for non-invasive and real-time detection of various protein biomarkers in point-of-care.}, keywords = {}, pubstate = {published}, tppubtype = {article} } This work reports a novel label-free sensor combining photonic crystals and molecularly-imprinted polymer materials for targeting a protein in human samples within levels of clinical interest. This concept was applied to detect fibrinopeptide B (FPB) in urine, a biomarker of venous thromboembolism, which is a disease of great concern and demands innovative point-of-care devices for improved diagnosis. The molecularly-imprinted photonic polymer (MIPP) was obtained by tailoring an imprinted polymer on highly ordered silica nanoparticles assembled by vertical deposition. Owing to the hierarchical structure, the resulting MIPP exhibited optical properties that changed upon rebinding of the target analyte, FPB. Thus, the changes in reflectance intensity enabled a rapid and sensitive detection of FPB in human urine. The observed response was linear between 0.2 ng mL-1 and 22 ng mL-1 and showed a limit of detection of 0.13 ng mL-1. These features of the sensing material allow the assessment of urinary FPB at relevant clinical levels. In addition, the sensor was selective for FPB compared to the standard biomarker of venous thromboembolism, D-Dimer. The stability of the material was evidenced by the reusability study, which demonstrated reversibility of the maximum intensity after three cycles of recognition and regeneration. Moreover, the sensor showed good performance for the spiked FPB detection in control human urine. Overall, the application of such label-free sensor offers high selectivity and stability, as well as easy operation. It may constitute an alternative method for non-invasive and real-time detection of various protein biomarkers in point-of-care. |
GV Martins, AC Marques, E Fortunato, M. Goreti F. Sales Paper-based (bio)sensor for label-free detection of 3-nitrotyrosine in human urine samples using molecular imprinted polymer (Journal Article) Sensing and Bio-Sensing Research, 2 , pp. 100333, 2020. @article{Martins.2020, title = {Paper-based (bio)sensor for label-free detection of 3-nitrotyrosine in human urine samples using molecular imprinted polymer}, author = {GV Martins and AC Marques and E Fortunato and M. Goreti F. Sales }, url = {https://doi.org/10.1016/j.sbsr.2020.100333}, doi = {10.1016/j.sbsr.2020.100333}, year = {2020}, date = {2020-03-02}, journal = {Sensing and Bio-Sensing Research}, volume = {2}, pages = {100333}, abstract = {Over the last years, paper technology has been widely spread as a more affordable, sustainable and reliable support material to be incorporated in the design of point-of-care (POC) diagnostic devices. However, the single work employing a paper-based device for 3-nitrotyrosine (3-NT), a relevant biomarker for oxidative stress (OS) that is a major origin for many diseases, is incapable of reading successfully complex samples because every species that oxidizes before ~0.75 V will also contribute to the final response. Thus, the introduction of a selective element was made into this set-up by including a molecularly-imprinted polymer (MIP) tailored in-situ. Herein, a novel MIP for 3-NT was assembled directly on a paper platform, made conductive with carbon ink and suitable for an electrochemical transduction. The biomimetic material was produced by electropolymerization of phenol after optimizing several experimental parameters, such a scan-rate, number of cycles, range of potential applied, monomer and template concentrations. Under optimal conditions, the label-free sensor was able to respond to 3-NT from 500 nM to 1 mM, yielding a limit of detection of 22.3 nM. Finally, the applicability of the (bio)sensor was tested by performing calibration assays in human urine samples and a good performance was obtained in terms of sensitivity, selectivity and reproducibility. Overall, the attributes of the herein described sensing approach can be compared to a very limited number of other electrochemical devices, that are still using a conventional three electrode system, making this paper-sustained device the first electrochemical (bio)sensor with potential to become a portable and low-cost diagnostic tool for 3-NT. In general, the incorporation of molecular imprinting technology coupled to electrochemical transduction enabled the fabrication of suitable smart sensors for wide screening approaches.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Over the last years, paper technology has been widely spread as a more affordable, sustainable and reliable support material to be incorporated in the design of point-of-care (POC) diagnostic devices. However, the single work employing a paper-based device for 3-nitrotyrosine (3-NT), a relevant biomarker for oxidative stress (OS) that is a major origin for many diseases, is incapable of reading successfully complex samples because every species that oxidizes before ~0.75 V will also contribute to the final response. Thus, the introduction of a selective element was made into this set-up by including a molecularly-imprinted polymer (MIP) tailored in-situ. Herein, a novel MIP for 3-NT was assembled directly on a paper platform, made conductive with carbon ink and suitable for an electrochemical transduction. The biomimetic material was produced by electropolymerization of phenol after optimizing several experimental parameters, such a scan-rate, number of cycles, range of potential applied, monomer and template concentrations. Under optimal conditions, the label-free sensor was able to respond to 3-NT from 500 nM to 1 mM, yielding a limit of detection of 22.3 nM. Finally, the applicability of the (bio)sensor was tested by performing calibration assays in human urine samples and a good performance was obtained in terms of sensitivity, selectivity and reproducibility. Overall, the attributes of the herein described sensing approach can be compared to a very limited number of other electrochemical devices, that are still using a conventional three electrode system, making this paper-sustained device the first electrochemical (bio)sensor with potential to become a portable and low-cost diagnostic tool for 3-NT. In general, the incorporation of molecular imprinting technology coupled to electrochemical transduction enabled the fabrication of suitable smart sensors for wide screening approaches. |
Verónica M. Serrano, A. Rita Cardoso, Mário Diniz, M. Goreti F. Sales In-situ production of Histamine-imprinted polymeric materials for electrochemical monitoring of fish (Journal Article) Sensors and Actuators B: Chemical, 311 , pp. 127902, 2020. @article{Serrano.2019, title = {In-situ production of Histamine-imprinted polymeric materials for electrochemical monitoring of fish}, author = {Verónica M. Serrano and A. Rita Cardoso and Mário Diniz and M. Goreti F. Sales}, url = {https://doi.org/10.1016/j.snb.2020.127902}, doi = {10.1016/j.snb.2020.127902}, year = {2020}, date = {2020-02-20}, journal = {Sensors and Actuators B: Chemical}, volume = {311}, pages = {127902}, abstract = {Histamine (HIS) is a major public health problem due to its toxic properties. High levels can cause a chronic toxicity as poisoning and can be used as a signal of food hygiene. Thus, a new electrochemical sensor for HIS detection in fish is presented herein, prepared by tailoring a molecularly imprinted polymer (MIP) sensing material on a gold screen-printed electrode (Au-SPEs), in which the polymeric film was generated in-situ. This film was obtained by electropolymerizing aniline under conditions that preserved the chemical structure of HIS. Raman spectroscopy followed the chemical changes occurring at each stage of the electrode modification. The device performance was assessed by evaluating the changes in electron transfer properties of a standard redox probe [Fe(CN)6]4−/[Fe(CN)6]3−, by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). EIS was also used to calibrate the sensor, being the standard solutions prepared under different background media (electrolyte or a blank sample of fish extract). The device displayed a linear response from 500 nM to 1 mM, with a limit of detection of 210 nM, and a selective behaviour against tyramine, another amine related to fish degradation. The sensing system was further employed to monitor the HIS content in samples in different time points of storage at ambient temperature. The obtained results were in agreement with the ELISA method, while offering more reproducible data. In general, the optimized sensor allowed reproducible and accurate analysis of fish samples subject to degradation and was completely assembled in-situ, in a very simple and straightforward approach. The device is low cost and suitable for further adaptation to on-site analysis, as required in food control.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Histamine (HIS) is a major public health problem due to its toxic properties. High levels can cause a chronic toxicity as poisoning and can be used as a signal of food hygiene. Thus, a new electrochemical sensor for HIS detection in fish is presented herein, prepared by tailoring a molecularly imprinted polymer (MIP) sensing material on a gold screen-printed electrode (Au-SPEs), in which the polymeric film was generated in-situ. This film was obtained by electropolymerizing aniline under conditions that preserved the chemical structure of HIS. Raman spectroscopy followed the chemical changes occurring at each stage of the electrode modification. The device performance was assessed by evaluating the changes in electron transfer properties of a standard redox probe [Fe(CN)6]4−/[Fe(CN)6]3−, by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). EIS was also used to calibrate the sensor, being the standard solutions prepared under different background media (electrolyte or a blank sample of fish extract). The device displayed a linear response from 500 nM to 1 mM, with a limit of detection of 210 nM, and a selective behaviour against tyramine, another amine related to fish degradation. The sensing system was further employed to monitor the HIS content in samples in different time points of storage at ambient temperature. The obtained results were in agreement with the ELISA method, while offering more reproducible data. In general, the optimized sensor allowed reproducible and accurate analysis of fish samples subject to degradation and was completely assembled in-situ, in a very simple and straightforward approach. The device is low cost and suitable for further adaptation to on-site analysis, as required in food control. |
Carla N.O. Teixeira, M. Goreti F. Sales A cellulose-based colour test-strip for equipment-free drug detection on-site: application to sulfadiazine in aquatic environment (Journal Article) SN Applied Sciences, 2 , pp. 325, 2020. @article{Teixeira.2019, title = {A cellulose-based colour test-strip for equipment-free drug detection on-site: application to sulfadiazine in aquatic environment}, author = {Carla N.O. Teixeira and M. Goreti F. Sales }, url = {https://doi.org/10.1007/s42452-020-2143-3}, doi = {10.1007/s42452-020-2143-3}, year = {2020}, date = {2020-02-03}, journal = {SN Applied Sciences}, volume = {2}, pages = {325}, abstract = {This work develops a simple and innovative test-strip to monitor antibiotics in aquaculture facilities by an equipment-free approach. It consists of a low-cost disposable cellulose paper that was chemically modified to produce a colour change when in contact with a given antibiotic. In brief, the cellulose substrate was subject to oxidation with periodate, followed by amination with chitosan binding and modification with Cu(II). The test strip was then dipped in the target solution and the intensity of the colour generated therein revealed the concentration of antibiotic present for concentrations higher than 0.5 mM. The higher the concentration in sulfadiazine (SDZ), the more intense the pink colour formed in the final solution, which was also turbid due to the insolubility of the formed product. This colour intensity also varied linearly with the logarithm of the SDZ concentration (from 0.5 to 5 mM), when plotted against the sum of the RGB coordinates extracted from digital pictures. The linear equation of this response was represented by (R + G + B) = − 256.1 log(SDZ, mol/L) − 362.0, with an R-squared of 0.9913. The test-strip was stable for at least 15 days and was selective in the presence of tetracycline and difloxacin, while the response to other members of the sulfadiazine family requires prior evaluation. Overall, the test-strips developed herein are inexpensive and provide valuable (semi-) quantitative data for monitoring SDZ in waters, a most valuable approach to control and reduce the level of antibiotics in fish tanks, which in turn may reduce the costs of fish production and the environmental concerns linked to this practice. Moreover, the test strip uses a cellulose substrate that has little environmental impact upon discard.}, keywords = {}, pubstate = {published}, tppubtype = {article} } This work develops a simple and innovative test-strip to monitor antibiotics in aquaculture facilities by an equipment-free approach. It consists of a low-cost disposable cellulose paper that was chemically modified to produce a colour change when in contact with a given antibiotic. In brief, the cellulose substrate was subject to oxidation with periodate, followed by amination with chitosan binding and modification with Cu(II). The test strip was then dipped in the target solution and the intensity of the colour generated therein revealed the concentration of antibiotic present for concentrations higher than 0.5 mM. The higher the concentration in sulfadiazine (SDZ), the more intense the pink colour formed in the final solution, which was also turbid due to the insolubility of the formed product. This colour intensity also varied linearly with the logarithm of the SDZ concentration (from 0.5 to 5 mM), when plotted against the sum of the RGB coordinates extracted from digital pictures. The linear equation of this response was represented by (R + G + B) = − 256.1 log(SDZ, mol/L) − 362.0, with an R-squared of 0.9913. The test-strip was stable for at least 15 days and was selective in the presence of tetracycline and difloxacin, while the response to other members of the sulfadiazine family requires prior evaluation. Overall, the test-strips developed herein are inexpensive and provide valuable (semi-) quantitative data for monitoring SDZ in waters, a most valuable approach to control and reduce the level of antibiotics in fish tanks, which in turn may reduce the costs of fish production and the environmental concerns linked to this practice. Moreover, the test strip uses a cellulose substrate that has little environmental impact upon discard. |
A. Margarida L. Piloto, D.S.M. Ribeiro, S. Sofia M. Rodrigues, João L.M. Santos, M. Goreti F. Sales Label-free quantum dot conjugates for human protein IL-2 based on molecularly imprinted polymers (Journal Article) Sensors and Actuators B: Chemical, 304 , pp. 127343, 2020. @article{Piloto.2019, title = {Label-free quantum dot conjugates for human protein IL-2 based on molecularly imprinted polymers}, author = {A. Margarida L. Piloto and D.S.M. Ribeiro and S. Sofia M. Rodrigues and João L.M. Santos and M. Goreti F. Sales}, url = {https://doi.org/10.1016/j.snb.2019.127343}, doi = {10.1016/j.snb.2019.127343}, year = {2020}, date = {2020-01-01}, journal = {Sensors and Actuators B: Chemical}, volume = {304}, pages = {127343}, abstract = {Herein, the development of a fluorescent-based sensor by combining quantum dots (QDs) with molecularly-imprinted technology (MIT), intensively optimized to generate exceptional operating features is presented. This sensor is designed to target human interleukin-2 (IL-2) in synthetic human serum. IL-2 is a regulatory protein released as a triggered response from the immune system towards an inflammation. For this purpose, cadmium telluride (CdTe) QDs are prepared with 3-mercaptopropionic acid (MPA) and modified afterwards to produce an IL-2 imprinted polymer with methacrylic acid and N,N´-methylenebis(acrylamide), upon removal of the template under optimized conditions. During IL-2 rebinding, the fluorescence intensity of CdTe@MPA QDs is quenched in a concentration dependent manner. Using surface imprinting technology, the optimal fluorescence signals yielded a linear response versus logarithm of IL-2 concentration from 35 fg/ml to 39 pg/ml, in a 1000-fold diluted synthetic human serum. The limit of detection obtained is 5.91 fg/ml, lying below the concentration levels of IL-2 with clinical interest for cancer diagnosis (9.4–19.2 pg/ml). Overall, the method presented herein is a demonstration that the combination of MIP and QDs for protein detection constitutes a powerful tool in clinical analysis, providing low cost, sensitive and quick responses. The same concept may be further extended to other proteins of interest.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Herein, the development of a fluorescent-based sensor by combining quantum dots (QDs) with molecularly-imprinted technology (MIT), intensively optimized to generate exceptional operating features is presented. This sensor is designed to target human interleukin-2 (IL-2) in synthetic human serum. IL-2 is a regulatory protein released as a triggered response from the immune system towards an inflammation. For this purpose, cadmium telluride (CdTe) QDs are prepared with 3-mercaptopropionic acid (MPA) and modified afterwards to produce an IL-2 imprinted polymer with methacrylic acid and N,N´-methylenebis(acrylamide), upon removal of the template under optimized conditions. During IL-2 rebinding, the fluorescence intensity of CdTe@MPA QDs is quenched in a concentration dependent manner. Using surface imprinting technology, the optimal fluorescence signals yielded a linear response versus logarithm of IL-2 concentration from 35 fg/ml to 39 pg/ml, in a 1000-fold diluted synthetic human serum. The limit of detection obtained is 5.91 fg/ml, lying below the concentration levels of IL-2 with clinical interest for cancer diagnosis (9.4–19.2 pg/ml). Overall, the method presented herein is a demonstration that the combination of MIP and QDs for protein detection constitutes a powerful tool in clinical analysis, providing low cost, sensitive and quick responses. The same concept may be further extended to other proteins of interest. |
2019
Felismina T. C. Moreira, M. Goreti F. Sales Autonomous biosensing device merged with photovoltaic technology for cancer biomarker detection (Journal Article) Journal of Electroanalytical Chemistry, 855 , pp. 113611, 2019. @article{Felis.DSSC.2019, title = {Autonomous biosensing device merged with photovoltaic technology for cancer biomarker detection}, author = {Felismina T. C. Moreira and M. Goreti F. Sales }, url = {https://doi.org/10.1016/j.jelechem.2019.113611}, doi = {10.1016/j.jelechem.2019.113611}, year = {2019}, date = {2019-11-06}, journal = {Journal of Electroanalytical Chemistry}, volume = {855}, pages = {113611}, abstract = {Pursuing self-powered biosensors, this work describes a hybrid device combining a sensing electrochemical system with a photovoltaic cell. The sensing system is a molecularly-imprinted polymer (MIP) and the photovoltaic cell is a dye-sensitized solar cell (DSSC). The biosensing film is tailored on a typical counter electrode (CE) of a conventional DSSC, turning the resulting hybrid system sensitive to a target analyte. The target analyte selected herein was carcinogenic embryonic antigen (CEA), a typical cancer biomarker in colorectal cancer. In detail, the MIP film was tailored on a highly conductive polyaniline CE, by electropolymerizing aniline on top of it, in near basic pH and in the presence of CEA. The protein was later removed by proteinase K action. The resulting vacant sites were able to rebind CEA, as confirmed in a 3-electrodes set-up, by square-wave voltammetry (SWV) and electrochemical impedance spectroscopy (EIS) studies. The hybrid DSSC/biosensing system was tested by incubating the CEA solution in urine sample on the biosensing film and using the resulting surface to act as counter electrode of the photovoltaic cell. The photovoltaic features of the resulting device confirmed the dependency between power and CEA concentration. In this new set-up, a linear trend was observed between power and log CEA concentration, down to 0.025 ng mL−1 when urine samples were tested. Overall, the hybrid device is inexpensive and self-powered, which holds a great impact in point-of-care applications, especially in low-income countries. This concept may be further extended to other biomarkers implicated in several diseases or other target molecules involved in food safety or environmental monitoring needs.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Pursuing self-powered biosensors, this work describes a hybrid device combining a sensing electrochemical system with a photovoltaic cell. The sensing system is a molecularly-imprinted polymer (MIP) and the photovoltaic cell is a dye-sensitized solar cell (DSSC). The biosensing film is tailored on a typical counter electrode (CE) of a conventional DSSC, turning the resulting hybrid system sensitive to a target analyte. The target analyte selected herein was carcinogenic embryonic antigen (CEA), a typical cancer biomarker in colorectal cancer. In detail, the MIP film was tailored on a highly conductive polyaniline CE, by electropolymerizing aniline on top of it, in near basic pH and in the presence of CEA. The protein was later removed by proteinase K action. The resulting vacant sites were able to rebind CEA, as confirmed in a 3-electrodes set-up, by square-wave voltammetry (SWV) and electrochemical impedance spectroscopy (EIS) studies. The hybrid DSSC/biosensing system was tested by incubating the CEA solution in urine sample on the biosensing film and using the resulting surface to act as counter electrode of the photovoltaic cell. The photovoltaic features of the resulting device confirmed the dependency between power and CEA concentration. In this new set-up, a linear trend was observed between power and log CEA concentration, down to 0.025 ng mL−1 when urine samples were tested. Overall, the hybrid device is inexpensive and self-powered, which holds a great impact in point-of-care applications, especially in low-income countries. This concept may be further extended to other biomarkers implicated in several diseases or other target molecules involved in food safety or environmental monitoring needs. |
Mariana C.C.G.Carneiro, Ana Sousa-Castillo, Miguel A. Correa-Duarte, M. Goreti F. Sales Dual biorecognition by combining molecularly-imprinted polymer and antibody in SERS detection. Application to carcinoembryonic antigen (Journal Article) Biosensors and Bioelectronics, 146 , pp. 111761, 2019. @article{Carneiro.2019, title = {Dual biorecognition by combining molecularly-imprinted polymer and antibody in SERS detection. Application to carcinoembryonic antigen}, author = {Mariana C.C.G.Carneiro and Ana Sousa-Castillo and Miguel A. Correa-Duarte and M. Goreti F. Sales }, url = {https://doi.org/10.1016/j.bios.2019.111761}, doi = {10.1016/j.bios.2019.111761}, year = {2019}, date = {2019-10-08}, journal = {Biosensors and Bioelectronics}, volume = {146}, pages = {111761}, abstract = {This work reports the innovative combination of a molecularly-imprinted polymer (MIP) and a natural antibody for the accurate surface-enhanced Raman spectroscopy (SERS) detection of carcinoembryonic antigen (CEA). The MIP material acted as a pre-concentration scheme for the target protein, while the natural antibody was responsible to signal the presence of CEA on the MIP platform. Gold-based screen-printed electrodes were used as substrate and gallic acid (GA) was used herein for the first time in the assembly of a MIP film, by electropolymerization, in the presence of CEA. This layer was further covered by a second ultra-thin film of electropolymerized benzoic acid (BA), to avoid non-specific binding. The rebinding features of the MIP film were evaluated by electrochemical impedance spectroscopy (EIS) and a linear response was observed from 1 to 1000 ng/mL. For a sensitive SERS detection, the MIP film was first incubated in sample containing CEA and next incubated in SERS tag. For the SERS tag, gold nanostars (AuNSs) were employed as metal support, coupled to 4-aminothiophenol (4-ATP) as Raman reporter and to a natural antibody for CEA as recognition element. The overall system showed a sensitive response down to 1.0 ng/mL, which was different from the blank signal. Overall, the innovative approach presented herein combines the advantages of using two different targeting elements for CEA. The costs and time of MIP production were substantially low due to selection of electropolymerization approach and the proposal described herein may be extended to other target molecules.}, keywords = {}, pubstate = {published}, tppubtype = {article} } This work reports the innovative combination of a molecularly-imprinted polymer (MIP) and a natural antibody for the accurate surface-enhanced Raman spectroscopy (SERS) detection of carcinoembryonic antigen (CEA). The MIP material acted as a pre-concentration scheme for the target protein, while the natural antibody was responsible to signal the presence of CEA on the MIP platform. Gold-based screen-printed electrodes were used as substrate and gallic acid (GA) was used herein for the first time in the assembly of a MIP film, by electropolymerization, in the presence of CEA. This layer was further covered by a second ultra-thin film of electropolymerized benzoic acid (BA), to avoid non-specific binding. The rebinding features of the MIP film were evaluated by electrochemical impedance spectroscopy (EIS) and a linear response was observed from 1 to 1000 ng/mL. For a sensitive SERS detection, the MIP film was first incubated in sample containing CEA and next incubated in SERS tag. For the SERS tag, gold nanostars (AuNSs) were employed as metal support, coupled to 4-aminothiophenol (4-ATP) as Raman reporter and to a natural antibody for CEA as recognition element. The overall system showed a sensitive response down to 1.0 ng/mL, which was different from the blank signal. Overall, the innovative approach presented herein combines the advantages of using two different targeting elements for CEA. The costs and time of MIP production were substantially low due to selection of electropolymerization approach and the proposal described herein may be extended to other target molecules. |
GV Martins, AC Marques, E Fortunato, M. Goreti F. Sales Wax-printed paper-based device for direct electrochemical detection of 3-nitrotyrosine (Journal Article) Electrochimica Acta, 284 , pp. 60-68, 2019. @article{Gabi.2019, title = {Wax-printed paper-based device for direct electrochemical detection of 3-nitrotyrosine}, author = {GV Martins and AC Marques and E Fortunato and M. Goreti F. Sales}, url = {https://doi.org/10.1016/j.electacta.2018.07.150}, doi = {10.1016/j.electacta.2018.07.150}, year = {2019}, date = {2019-07-23}, journal = {Electrochimica Acta}, volume = {284}, pages = {60-68}, abstract = {An overview of the last trends in lab-on-chip technology highlights the continuous development of biosensing approaches in terms of simplicity, low-cost, and quick response, with a higher sensitivity and selectivity. In this context, electrochemical sensors arrived to overcome the need to develop small, accurate, portable and compact sensing devices, compatible with routine use in loco analysis, especially in point-of-care (POC) assessment. Herein, we have presented the first paper-based electrochemical sensor towards the detection of 3-nitrotyrosine (3-NT), a relevant oxidative stress biomarker. This innovative sensor was designed by, first, modifying paper to become a hydrophobic support and, second applying carbon and silver conductive inks to generate a three electrode-system on a small spot. An intensive voltammetric investigation of the paper-based screen-printed electrodes (SPEs), including the study of different redox-probes, scan-rate values, probe concentrations and supporting electrolyte solutions, confirmed their suitable and reliable electrochemical performance. Square wave voltammetry (SWV) was employed to assess the sensitivity of the proposed sensor at various concentrations of 3-NT, ranging from 500 nM to 1 mM, enabling a low detection limit (LOD) of 49.2 nM. The interference of co-existing species was also tested and good selectivity against 3-NT was accomplished. Overall, this flexible paper-based platform constitutes a promising sensor material towards a quick, sensitive, cost-effective, sustainable and reproducible detection of 3-NT biomarker.}, keywords = {}, pubstate = {published}, tppubtype = {article} } An overview of the last trends in lab-on-chip technology highlights the continuous development of biosensing approaches in terms of simplicity, low-cost, and quick response, with a higher sensitivity and selectivity. In this context, electrochemical sensors arrived to overcome the need to develop small, accurate, portable and compact sensing devices, compatible with routine use in loco analysis, especially in point-of-care (POC) assessment. Herein, we have presented the first paper-based electrochemical sensor towards the detection of 3-nitrotyrosine (3-NT), a relevant oxidative stress biomarker. This innovative sensor was designed by, first, modifying paper to become a hydrophobic support and, second applying carbon and silver conductive inks to generate a three electrode-system on a small spot. An intensive voltammetric investigation of the paper-based screen-printed electrodes (SPEs), including the study of different redox-probes, scan-rate values, probe concentrations and supporting electrolyte solutions, confirmed their suitable and reliable electrochemical performance. Square wave voltammetry (SWV) was employed to assess the sensitivity of the proposed sensor at various concentrations of 3-NT, ranging from 500 nM to 1 mM, enabling a low detection limit (LOD) of 49.2 nM. The interference of co-existing species was also tested and good selectivity against 3-NT was accomplished. Overall, this flexible paper-based platform constitutes a promising sensor material towards a quick, sensitive, cost-effective, sustainable and reproducible detection of 3-NT biomarker. |
TSCR Rebelo, R Costa, ATSC Brandão, AF Silva, M. Goreti F. Sales, and Carlos M. Pereira Molecularly imprinted polymer SPE sensor for analysis of CA-125 on serum (Journal Article) Analytica Chimica Acta, 1082 , pp. 12-135, 2019. @article{Rebelo.2019, title = {Molecularly imprinted polymer SPE sensor for analysis of CA-125 on serum}, author = {TSCR Rebelo and R Costa and ATSC Brandão and AF Silva and M. Goreti F. Sales and and Carlos M. Pereira }, url = {https://doi.org/10.1016/j.aca.2019.07.050}, doi = {10.1016/j.aca.2019.07.050}, year = {2019}, date = {2019-07-19}, journal = {Analytica Chimica Acta}, volume = {1082}, pages = {12-135}, abstract = {Considering the high incidence level and mortality rate of ovarian cancer, particularly among the European female population, the carbohydrate antigen 125 (CA-125) was selected as the protein target for this study for the development of a MIP-based biosensor. This work presents the development of molecular imprinting polymers (MIPs) on gold electrode surface for CA-125 biomarker recognition. The preparation of the CA-125 imprinting was obtained by electropolymerization of pyrrole (Py) monomer in a gold electrode using cyclic voltammetry (CV) in order to obtain highly selective materials with great molecular recognition capability. The quantification of CA-125 biomarker was made through the comparison of two methods: electrochemical (square wave voltammetry -SWV) and optical transduction (surface plasmon resonance -SPR). SWV has been widely used in biological molecules analysis since it is a fast and sensitive technique. In turn, SPR is a non-destructive optical technique that provides high-quality analytical data of CA-125 biomarker interactions with MIP. Several analytical parameters, such as sensitivity, linear response interval, and detection limit were determined to proceed to the performance evaluation of the electrochemical and optical transduction used in the development of the CA-125 biosensor. The biosensor based in the electrochemical transduction was the one that presented the best analytical parameters, yielding a good selectivity and a detection limit (LOD) of 0.01 U/mL, providing a linear concentration range between 0.01 and 500 U/mL. This electrochemical biosensor was selected for the study and it was successfully applied in the CA-125 analysis in artificial serum samples with recovery rates ranging from 91 to 105% with an average relative error of 5.8%.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Considering the high incidence level and mortality rate of ovarian cancer, particularly among the European female population, the carbohydrate antigen 125 (CA-125) was selected as the protein target for this study for the development of a MIP-based biosensor. This work presents the development of molecular imprinting polymers (MIPs) on gold electrode surface for CA-125 biomarker recognition. The preparation of the CA-125 imprinting was obtained by electropolymerization of pyrrole (Py) monomer in a gold electrode using cyclic voltammetry (CV) in order to obtain highly selective materials with great molecular recognition capability. The quantification of CA-125 biomarker was made through the comparison of two methods: electrochemical (square wave voltammetry -SWV) and optical transduction (surface plasmon resonance -SPR). SWV has been widely used in biological molecules analysis since it is a fast and sensitive technique. In turn, SPR is a non-destructive optical technique that provides high-quality analytical data of CA-125 biomarker interactions with MIP. Several analytical parameters, such as sensitivity, linear response interval, and detection limit were determined to proceed to the performance evaluation of the electrochemical and optical transduction used in the development of the CA-125 biosensor. The biosensor based in the electrochemical transduction was the one that presented the best analytical parameters, yielding a good selectivity and a detection limit (LOD) of 0.01 U/mL, providing a linear concentration range between 0.01 and 500 U/mL. This electrochemical biosensor was selected for the study and it was successfully applied in the CA-125 analysis in artificial serum samples with recovery rates ranging from 91 to 105% with an average relative error of 5.8%. |
C Hora, F Santos, M. Goreti F. Sales, and D Ivanou, A Mendes Dye-Sensitized Solar Cells for efficient solar and artificial light conversion (Journal Article) ACS Sustainable Chemical Engineering, 7 (15), pp. 13464-13470, 2019. @article{Hora.2019, title = {Dye-Sensitized Solar Cells for efficient solar and artificial light conversion}, author = {C Hora and F Santos and M. Goreti F. Sales and and D Ivanou and A Mendes }, url = {https://doi.org/10.1021/acssuschemeng.9b02990}, doi = {10.1021/acssuschemeng.9b02990}, year = {2019}, date = {2019-07-12}, journal = {ACS Sustainable Chemical Engineering}, volume = {7}, number = {15}, pages = {13464-13470}, abstract = {Progress in dye-sensitized solar cells (DSSCs) has been benchmarked with N719 dye-based devices. However, power conversion efficiency (PCE) improvements performed in low-energy-performing devices cannot be extrapolated to high-performing ones. This points to the need for using a high PCE reference DSSC device, which preferably should be possible for preparation using readily available commercial reactants and parts. This study reports an optimized DSSC prepared with commercial reactants, displaying a PCE of up to 9.84% under simulated solar light and of 28.7% under artificial room light. The efficient light harvesting in the photoanode and electron recombination suppression in the photoanode/electrolyte interface were systematically optimized; the thickness and light-scattering ability of the photoanode mesoporous layers were tuned to maximize light harvesting and minimize the recombination losses. Electron back recombination with electrolyte was minimized using a TiO2 blocking layer and treating the mesoporous layer of TiO2 with TiCl4. Finally, despite the use of a light-scattering TiO2 coating over the mesoporous layer, the use of a light reflection layer applied to the back of the devices proved to improve the PCE further. KEYWORDS:}, keywords = {}, pubstate = {published}, tppubtype = {article} } Progress in dye-sensitized solar cells (DSSCs) has been benchmarked with N719 dye-based devices. However, power conversion efficiency (PCE) improvements performed in low-energy-performing devices cannot be extrapolated to high-performing ones. This points to the need for using a high PCE reference DSSC device, which preferably should be possible for preparation using readily available commercial reactants and parts. This study reports an optimized DSSC prepared with commercial reactants, displaying a PCE of up to 9.84% under simulated solar light and of 28.7% under artificial room light. The efficient light harvesting in the photoanode and electron recombination suppression in the photoanode/electrolyte interface were systematically optimized; the thickness and light-scattering ability of the photoanode mesoporous layers were tuned to maximize light harvesting and minimize the recombination losses. Electron back recombination with electrolyte was minimized using a TiO2 blocking layer and treating the mesoporous layer of TiO2 with TiCl4. Finally, despite the use of a light-scattering TiO2 coating over the mesoporous layer, the use of a light reflection layer applied to the back of the devices proved to improve the PCE further. KEYWORDS: |
A.P.M. Tavares, Liliana A.A.N.A. Truta, Felismina T.C. Moreira, Liliana P.T. Carneiro, M. Goreti F. Sales A Self-powered and self-signalled autonomous electrochemical biosensor applied to cancinoembryonic antigen determination (Journal Article) Biosensors and Bioelectronics, 140 , pp. 111320, 2019. @article{Tavares.Tese2.2019, title = {A Self-powered and self-signalled autonomous electrochemical biosensor applied to cancinoembryonic antigen determination}, author = {A.P.M. Tavares and Liliana A.A.N.A. Truta and Felismina T.C. Moreira and Liliana P.T. Carneiro and M. Goreti F. Sales}, url = {https://doi.org/10.1016/j.bios.2019.111320}, doi = {10.1016/j.bios.2019.111320}, year = {2019}, date = {2019-05-14}, journal = {Biosensors and Bioelectronics}, volume = {140}, pages = {111320}, abstract = {This work describes a novel and disruptive electrochemical biosensing device that is self-powered by light and self-signalled by an optical readout. Electrical energy requirements are ensured by a photovoltaic cell that is a dye sensitized solar cell (DSSC), in which one of the electrodes is the biosensing unit. The readout converts electrical energy into colour by an electrochromic cell and signals the concentration dependent event. This device was designed to target a cancer biomarker, cancinoembryonic antigen (CEA). In brief, the sensing unit was assembled on a conductive glass substrate with a highly conductive poly(3,4-ethylenedioxythiophene) (PEDOT) layer, using a molecularly-imprinted polymer of polypyrrol (PPy) as biorecognition element. This sensing unit acted as the counter electrode (CE) of the DSSC, generating a hybrid device with a maximum power conversion efficiency of 3.45% for a photoanode area of 0.7 cm2. The hybrid DSSC/biosensor had an electrical output that was CEA concentration dependent from 100 ng/mL to 100 μg/mL, with a limit detection of 0.14 ng/mL in human urine samples. The electrochromic cell consisted of a PEDOT-based material and showed a colour gradient change for CEA concentrations, ranging from 0.1 ng/mL to 100 μg/mL. Overall, this self-powered and self-signalled set-up is equipment free and particularly suitable for point-of-care analysis (POC), being able to screen CEA in real samples and differentiating critical concentrations for establishing a diagnosis. It holds the potential to provide clinical relevant data anywhere, in a fully independent manner.}, keywords = {}, pubstate = {published}, tppubtype = {article} } This work describes a novel and disruptive electrochemical biosensing device that is self-powered by light and self-signalled by an optical readout. Electrical energy requirements are ensured by a photovoltaic cell that is a dye sensitized solar cell (DSSC), in which one of the electrodes is the biosensing unit. The readout converts electrical energy into colour by an electrochromic cell and signals the concentration dependent event. This device was designed to target a cancer biomarker, cancinoembryonic antigen (CEA). In brief, the sensing unit was assembled on a conductive glass substrate with a highly conductive poly(3,4-ethylenedioxythiophene) (PEDOT) layer, using a molecularly-imprinted polymer of polypyrrol (PPy) as biorecognition element. This sensing unit acted as the counter electrode (CE) of the DSSC, generating a hybrid device with a maximum power conversion efficiency of 3.45% for a photoanode area of 0.7 cm2. The hybrid DSSC/biosensor had an electrical output that was CEA concentration dependent from 100 ng/mL to 100 μg/mL, with a limit detection of 0.14 ng/mL in human urine samples. The electrochromic cell consisted of a PEDOT-based material and showed a colour gradient change for CEA concentrations, ranging from 0.1 ng/mL to 100 μg/mL. Overall, this self-powered and self-signalled set-up is equipment free and particularly suitable for point-of-care analysis (POC), being able to screen CEA in real samples and differentiating critical concentrations for establishing a diagnosis. It holds the potential to provide clinical relevant data anywhere, in a fully independent manner. |
A.P.M. Tavares, Liliana A.A.N.A. Truta, Felismina T.C. Moreira, G. Minas, M. Goreti F. Sales Biosensors and Bioelectronics, 137 , pp. 72-81, 2019. @article{Tavares.Tese1.2019, title = {Photovoltaics, plasmonics, plastic antibodies and electrochromism combined for a novel generation of self-powered and self-signalled electrochemical biomimetic sensors}, author = {A.P.M. Tavares and Liliana A.A.N.A. Truta and Felismina T.C. Moreira and G. Minas and M. Goreti F. Sales }, url = {https://doi.org/10.1016/j.bios.2019.04.055}, doi = {10.1016/j.bios.2019.04.055}, year = {2019}, date = {2019-05-02}, journal = {Biosensors and Bioelectronics}, volume = {137}, pages = {72-81}, abstract = {This work describes further developments into the self-powered and self-signalled biosensing system that merges photovoltaic cells, plastic antibodies and electrochromic cells into a single target. Herein, the plasmonic effect is introduced to improve the photoanode features of the photovoltaic cell, a dye sensitized solar cell (DSSC), and better electrocatalytic features are introduced in the electrode containing the sensing element. In brief, the DSSC had a counter-electrode of poly(3,4-ethylenedioxythiophene) on an FTO glass modified by a plastic antibody of 3,4-ethylenedioxythiophene and pyrrol. The photoanode had dye sensitized TiO2 modified with gold nanoparticles (AuNPs) to increase the cell efficiency, aiming to improve the sensitivity of the response of hybrid device for the target biomarker. The target biomarker was carcinoembryonic antigen (CEA). The response of the hybrid device evidenced a linear trend from 0.1 ng/mL to 10 μg/mL, with an anionic slope of 0.1431 per decade concentration. The response of the plastic antibody for CEA revealed great selectivity against other tumour markers (CA 15–3 or CA 125). The colour response of the electrochromic cell was also CEA concentration dependent and more sensitive when the hybrid device was set-up with a photoanode with AuNPs. A more intense blue colour was obtained when higher concentrations of CEA were present. Overall, this improved version of the self-powered and self-signalled set-up has zero-requirements and is particularly suitable for point-of-care analysis (POC). It is capable of screening CEA in real samples and differentiating clinical levels of interest. This concept opens new horizons into the current cancer screening approaches.}, keywords = {}, pubstate = {published}, tppubtype = {article} } This work describes further developments into the self-powered and self-signalled biosensing system that merges photovoltaic cells, plastic antibodies and electrochromic cells into a single target. Herein, the plasmonic effect is introduced to improve the photoanode features of the photovoltaic cell, a dye sensitized solar cell (DSSC), and better electrocatalytic features are introduced in the electrode containing the sensing element. In brief, the DSSC had a counter-electrode of poly(3,4-ethylenedioxythiophene) on an FTO glass modified by a plastic antibody of 3,4-ethylenedioxythiophene and pyrrol. The photoanode had dye sensitized TiO2 modified with gold nanoparticles (AuNPs) to increase the cell efficiency, aiming to improve the sensitivity of the response of hybrid device for the target biomarker. The target biomarker was carcinoembryonic antigen (CEA). The response of the hybrid device evidenced a linear trend from 0.1 ng/mL to 10 μg/mL, with an anionic slope of 0.1431 per decade concentration. The response of the plastic antibody for CEA revealed great selectivity against other tumour markers (CA 15–3 or CA 125). The colour response of the electrochromic cell was also CEA concentration dependent and more sensitive when the hybrid device was set-up with a photoanode with AuNPs. A more intense blue colour was obtained when higher concentrations of CEA were present. Overall, this improved version of the self-powered and self-signalled set-up has zero-requirements and is particularly suitable for point-of-care analysis (POC). It is capable of screening CEA in real samples and differentiating clinical levels of interest. This concept opens new horizons into the current cancer screening approaches. |
AR Cardoso, MH Sá, M. Goreti F. Sales An impedimetric molecularly-imprinted biosensor for Interleukin-1β determination, prepared by in-situ electropolymerization on carbon screen-printed electrodes (Journal Article) Bioelectrochemistry, 130 , pp. 107287, 2019. @article{Cardoso.IL1Beta.2019, title = {An impedimetric molecularly-imprinted biosensor for Interleukin-1β determination, prepared by in-situ electropolymerization on carbon screen-printed electrodes}, author = {AR Cardoso and MH Sá and M. Goreti F. Sales }, url = {https://doi.org/10.1016/j.bioelechem.2019.04.017}, doi = {10.1016/j.bioelechem.2019.04.017}, year = {2019}, date = {2019-04-24}, journal = {Bioelectrochemistry}, volume = {130}, pages = {107287}, abstract = {This work reports the first electrochemical molecularly imprinted polymer (MIP) sensor for Interleukin-1beta (IL-1β) detection, based on modified commercial screen-printed carbon electrode (SPCE) was successfully demonstrated. For this purpose, the carbon support was modified with a PEDOT/4-aminothiophenol layer prior to the MIP film to enhance sensitivity and signal stability. The MIP layer was constructed on top of this by electropolymerization of Eriochrome black T (EBT) in the presence of IL-1β. The several steps of the biosensor assembly was followed by Raman spectroscopy and electroanalytical techniques. Using electrochemical impedance spectroscopy (EIS), a linear response in the range of 60 pM to 600 nM, with a LOD of 1.5 pM with (S/N = 3) was obtained in neutral PBS. Selectivity tests of the MIP biosensor made in spiked synthetic serum samples as well as against other structurally related (Myoglobin, of similar shape and size) or competing compounds (Immunoglobulin G, also present in the human serum) confirmed the good selectivity of the biosensor. Overall, the biosensor described herein has the potential to provide a simple and quick way for on-site screening of IL-1β, with low sample/reagent consumption and enabling direct serum analysis, which constitutes a valuable alternative to other conventional methods.}, keywords = {}, pubstate = {published}, tppubtype = {article} } This work reports the first electrochemical molecularly imprinted polymer (MIP) sensor for Interleukin-1beta (IL-1β) detection, based on modified commercial screen-printed carbon electrode (SPCE) was successfully demonstrated. For this purpose, the carbon support was modified with a PEDOT/4-aminothiophenol layer prior to the MIP film to enhance sensitivity and signal stability. The MIP layer was constructed on top of this by electropolymerization of Eriochrome black T (EBT) in the presence of IL-1β. The several steps of the biosensor assembly was followed by Raman spectroscopy and electroanalytical techniques. Using electrochemical impedance spectroscopy (EIS), a linear response in the range of 60 pM to 600 nM, with a LOD of 1.5 pM with (S/N = 3) was obtained in neutral PBS. Selectivity tests of the MIP biosensor made in spiked synthetic serum samples as well as against other structurally related (Myoglobin, of similar shape and size) or competing compounds (Immunoglobulin G, also present in the human serum) confirmed the good selectivity of the biosensor. Overall, the biosensor described herein has the potential to provide a simple and quick way for on-site screening of IL-1β, with low sample/reagent consumption and enabling direct serum analysis, which constitutes a valuable alternative to other conventional methods. |
C. Luís, Y. Castaño-Guerrero, R. Soares, M. Goreti F. Sales, and R Fernandes Avoiding the Interference of Doxorubicin with MTT Measurements on the MCF-7 Breast Cancer Cell Line (Journal Article) Method Protocols, 2 (2), pp. 29, 2019. @article{Yuselis.2019, title = {Avoiding the Interference of Doxorubicin with MTT Measurements on the MCF-7 Breast Cancer Cell Line }, author = {C. Luís and Y. Castaño-Guerrero and R. Soares and M. Goreti F. Sales and and R Fernandes}, url = {https://doi.org/10.3390/mps2020029https://doi.org/10.3390/mps2020029}, doi = {10.3390/mps2020029}, year = {2019}, date = {2019-04-12}, journal = {Method Protocols}, volume = {2}, number = {2}, pages = {29}, abstract = {Doxorubicin (DOXO) is an adjuvant chemotherapy agent and is also commonly used in cell biology research. Cytotoxic assays in cell culture are frequently used in order to stablish drug concentrations that are useful for controlling cell proliferation. One common cytotoxic method used is 3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide (MTT). Our present research aims to support future studies in engaging MTT assay using DOXO that exhibits a strong red coloration and fluorescence, and so it is assumed that DOXO may interfere with commonly used colorimetric assays such as MTT. The interference of DOXO in the MTT determination was evaluated in a Breast Cancer cell line Michigan Cancer Foundation-7 (MCF-7). The interference was evaluated by means of spectroscopic methods in particular spectrophometry and fluorescence spectroscopy of MTT and DOXO. We postulate that the medium and the MTT reagent itself can interfere on the metabolic activity method, so in order to achieve better results, DMEM was replaced by a neutral buffer like Phosphate-buffered saline (PBS). This protocol may be extremely useful in future studies involving DOXO.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Doxorubicin (DOXO) is an adjuvant chemotherapy agent and is also commonly used in cell biology research. Cytotoxic assays in cell culture are frequently used in order to stablish drug concentrations that are useful for controlling cell proliferation. One common cytotoxic method used is 3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide (MTT). Our present research aims to support future studies in engaging MTT assay using DOXO that exhibits a strong red coloration and fluorescence, and so it is assumed that DOXO may interfere with commonly used colorimetric assays such as MTT. The interference of DOXO in the MTT determination was evaluated in a Breast Cancer cell line Michigan Cancer Foundation-7 (MCF-7). The interference was evaluated by means of spectroscopic methods in particular spectrophometry and fluorescence spectroscopy of MTT and DOXO. We postulate that the medium and the MTT reagent itself can interfere on the metabolic activity method, so in order to achieve better results, DMEM was replaced by a neutral buffer like Phosphate-buffered saline (PBS). This protocol may be extremely useful in future studies involving DOXO. |
Liliana A.A.N.A. Truta, M. Goreti F. Sales Carcinoembryonic antigen imprinting by electropolymerization on a common conductive glass support and its determination in serum samples (Journal Article) Sensors and Actuators B: Chemical, 287 , pp. 53-63, 2019. @article{Truta.Tese.2019, title = {Carcinoembryonic antigen imprinting by electropolymerization on a common conductive glass support and its determination in serum samples}, author = {Liliana A.A.N.A. Truta and M. Goreti F. Sales}, url = {https://doi.org/10.1016/j.snb.2019.02.033}, doi = {10.1016/j.snb.2019.02.033}, year = {2019}, date = {2019-02-08}, journal = {Sensors and Actuators B: Chemical}, volume = {287}, pages = {53-63}, abstract = {This work reports a novel approach to monitor Carcinoembryonic antigen (CEA) biomarker with molecular-imprinting technology assembled on a conductive glass surface. For this purpose, the polymerization was achieved by electrical stimulus on fluorine doped tin oxide (FTO)-glass modified with a homemade carbon ink (hCCI). The biomimetic material was assembled on top of this surface, by moulding CEA at the molecular level around a polyaminophenol (PAP) polymeric matrix. The CEA biomarker was previously incubated in the presence or not of aminophenylboronic acid (APBA), to evaluate the effect of negative charges at the rebinding site. Then, aminophenol (AP) monomer was electropolymerized on the modified FTO glass, acting as working electrode. The template was removed by enzymatic action. Likewise, a control material having only PAP and no CEA was also prepared. The resulting sensing films were evaluated by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV), and the chemical modifications on these after each stage of the assembly process was followed by Fourier Transform Infrared (FTIR) and Raman spectroscopies. Imprinted devices displayed good linear responses to CEA in EIS assays from 2.5 ng/mL to 1.5 μg/mL in phosphate buffer solution (PBS). A promising detection of CEA was, also, achieved in spiked foetal bovine serum (FBS) samples, with a limit of detection (LOD) of 3 ng/mL. Overall, the devices developed herein are promising tools for monitoring CEA in point-of-care (POC) applications, being able to detect lower concentrations than those in normal physiological levels. In addition, the biosensors offer low cost, high sensitivity and good selectivity, and may be used to couple to other reading devices.}, keywords = {}, pubstate = {published}, tppubtype = {article} } This work reports a novel approach to monitor Carcinoembryonic antigen (CEA) biomarker with molecular-imprinting technology assembled on a conductive glass surface. For this purpose, the polymerization was achieved by electrical stimulus on fluorine doped tin oxide (FTO)-glass modified with a homemade carbon ink (hCCI). The biomimetic material was assembled on top of this surface, by moulding CEA at the molecular level around a polyaminophenol (PAP) polymeric matrix. The CEA biomarker was previously incubated in the presence or not of aminophenylboronic acid (APBA), to evaluate the effect of negative charges at the rebinding site. Then, aminophenol (AP) monomer was electropolymerized on the modified FTO glass, acting as working electrode. The template was removed by enzymatic action. Likewise, a control material having only PAP and no CEA was also prepared. The resulting sensing films were evaluated by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV), and the chemical modifications on these after each stage of the assembly process was followed by Fourier Transform Infrared (FTIR) and Raman spectroscopies. Imprinted devices displayed good linear responses to CEA in EIS assays from 2.5 ng/mL to 1.5 μg/mL in phosphate buffer solution (PBS). A promising detection of CEA was, also, achieved in spiked foetal bovine serum (FBS) samples, with a limit of detection (LOD) of 3 ng/mL. Overall, the devices developed herein are promising tools for monitoring CEA in point-of-care (POC) applications, being able to detect lower concentrations than those in normal physiological levels. In addition, the biosensors offer low cost, high sensitivity and good selectivity, and may be used to couple to other reading devices. |
Liliana A.A.N.A. Truta, Sónia Pereira, C Hora, Tito Trindade, M. Goreti F. Sales Coupling gold nanoparticles to Dye-Sensitized Solar Cells for an increased efficiency (Journal Article) Electrochimica Acta, 300 , pp. 102-112, 2019. @article{Truta.Tese.2018, title = {Coupling gold nanoparticles to Dye-Sensitized Solar Cells for an increased efficiency}, author = {Liliana A.A.N.A. Truta and Sónia Pereira and C Hora and Tito Trindade and M. Goreti F. Sales }, url = {https://doi.org/10.1016/j.electacta.2019.01.050}, doi = {10.1016/j.electacta.2019.01.050}, year = {2019}, date = {2019-01-14}, journal = {Electrochimica Acta}, volume = {300}, pages = {102-112}, abstract = {New approaches for coupling Au NPs to the photoanode of dye sensitized solar cells (DSSCs) were proposed herein, aiming to improve the typical energy conversion efficiency of these cells. For this purpose, colloidal Au NPs with different particles sizes, ∼5 nm and ∼22 nm, were chemically synthesized and attached (i) directly to titanium dioxide (TiO2) or (ii) to TiO2 surface modified with siliceous shells enriched in dithiocarbamate moieties (SiO2/SiDTC). Photoanodes composed by films of TiO2 anatase, TiO2@Au NPs (∼5 nm and ∼22 nm), or TiO2 functionalized with SiO2/SiDTC, loaded with colloidal Au NPs, were made. DSSCs were set-up in a typical sandwich configuration, using the photoanode, a Pt counter electrode, and an iodide electrolyte solution (I−/I3−). In general, a relevant contribution in the plasmonic DSSC performance was evidenced by using Au NPs of ∼22 nm loaded in different amounts 23.9 wt%, 31.0 wt% and 44.0 wt%. Photoanodes composed by 23.9% of Au yielded an increment of 14.40% in photocurrent and of 11.21% in the overall power conversion efficiency (PCE), when compared to the conventional one. In turn, the new strategy used in the chemical modification of the conventional photoanodes with dithiocarbamate groups showed also a significant improvement of the DSSC parameters.}, keywords = {}, pubstate = {published}, tppubtype = {article} } New approaches for coupling Au NPs to the photoanode of dye sensitized solar cells (DSSCs) were proposed herein, aiming to improve the typical energy conversion efficiency of these cells. For this purpose, colloidal Au NPs with different particles sizes, ∼5 nm and ∼22 nm, were chemically synthesized and attached (i) directly to titanium dioxide (TiO2) or (ii) to TiO2 surface modified with siliceous shells enriched in dithiocarbamate moieties (SiO2/SiDTC). Photoanodes composed by films of TiO2 anatase, TiO2@Au NPs (∼5 nm and ∼22 nm), or TiO2 functionalized with SiO2/SiDTC, loaded with colloidal Au NPs, were made. DSSCs were set-up in a typical sandwich configuration, using the photoanode, a Pt counter electrode, and an iodide electrolyte solution (I−/I3−). In general, a relevant contribution in the plasmonic DSSC performance was evidenced by using Au NPs of ∼22 nm loaded in different amounts 23.9 wt%, 31.0 wt% and 44.0 wt%. Photoanodes composed by 23.9% of Au yielded an increment of 14.40% in photocurrent and of 11.21% in the overall power conversion efficiency (PCE), when compared to the conventional one. In turn, the new strategy used in the chemical modification of the conventional photoanodes with dithiocarbamate groups showed also a significant improvement of the DSSC parameters. |
2018
I Cunha, R Biltres, M. Goreti F. Sales, V Vasconcelos Aptamer-Based Biosensors to Detect Aquatic Phycotoxins and Cyanotoxins (Journal Article) Sensors, 17 (7), pp. 2367, 2018. @article{Cunha2018, title = {Aptamer-Based Biosensors to Detect Aquatic Phycotoxins and Cyanotoxins}, author = {I Cunha and R Biltres and M. Goreti F. Sales and V Vasconcelos}, url = {https://www.mdpi.com/1424-8220/18/7/2367}, doi = {10.3390/s18072367}, year = {2018}, date = {2018-07-20}, journal = {Sensors}, volume = {17}, number = {7}, pages = {2367}, abstract = {Aptasensors have a great potential for environmental monitoring, particularly for real-time on-site detection of aquatic toxins produced by marine and freshwater microorganisms (cyanobacteria, dinoflagellates, and diatoms), with several advantages over other biosensors that are worth considering. Freshwater monitoring is of vital importance for public health, in numerous human activities, and animal welfare, since these toxins may cause fatal intoxications. Similarly, in marine waters, very effective monitoring programs have been put in place in many countries to detect when toxins exceed established regulatory levels and accordingly enforce shellfish harvesting closures. Recent advances in the fields of aptamer selection, nanomaterials and communication technologies, offer a vast array of possibilities to develop new imaginative strategies to create improved, ultrasensitive, reliable and real-time devices, featuring unique characteristics to produce and amplify the signal. So far, not many strategies have been used to detect aquatic toxins, mostly limited to the optic and electrochemical sensors, the majority applied to detect microcystin-LR using a target-induced switching mode. The limits of detection of these aptasensors have been decreasing from the nM to the fM order of magnitude in the past 20 years. Aspects related to sensor components, performance, aptamers sequences, matrices analyzed and future perspectives, are considered and discussed.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Aptasensors have a great potential for environmental monitoring, particularly for real-time on-site detection of aquatic toxins produced by marine and freshwater microorganisms (cyanobacteria, dinoflagellates, and diatoms), with several advantages over other biosensors that are worth considering. Freshwater monitoring is of vital importance for public health, in numerous human activities, and animal welfare, since these toxins may cause fatal intoxications. Similarly, in marine waters, very effective monitoring programs have been put in place in many countries to detect when toxins exceed established regulatory levels and accordingly enforce shellfish harvesting closures. Recent advances in the fields of aptamer selection, nanomaterials and communication technologies, offer a vast array of possibilities to develop new imaginative strategies to create improved, ultrasensitive, reliable and real-time devices, featuring unique characteristics to produce and amplify the signal. So far, not many strategies have been used to detect aquatic toxins, mostly limited to the optic and electrochemical sensors, the majority applied to detect microcystin-LR using a target-induced switching mode. The limits of detection of these aptasensors have been decreasing from the nM to the fM order of magnitude in the past 20 years. Aspects related to sensor components, performance, aptamers sequences, matrices analyzed and future perspectives, are considered and discussed. |
Felismina T. C. Moreira, Liliana A.A.N.A. Truta, M. Goreti F. Sales Biomimetic materials assembled on a photovoltaic cell as a novel biosensing approach to cancer biomarker detection (Journal Article) Scientific Reports , 8 , pp. 10205 , 2018. @article{Felis.DSSC.2018, title = {Biomimetic materials assembled on a photovoltaic cell as a novel biosensing approach to cancer biomarker detection}, author = {Felismina T. C. Moreira and Liliana A.A.N.A. Truta and M. Goreti F. Sales }, url = {https://doi.org/10.1038/s41598-018-27884-2}, doi = {10.1038/s41598-018-27884-2}, year = {2018}, date = {2018-07-05}, journal = {Scientific Reports }, volume = {8}, pages = {10205 }, abstract = {This work describes for the first time the integration of Dye Sensitized Solar Cell (DSSC) technology in biosensors and biomimetic materials, opening doors towards a new dimension of autonomous screening devices that may be used in point-of-care, with zero-power requirements. DSSCs are fabricated with a counter electrode (CE) of polypyrrole (PPy) that was made responsive to a specific protein by biomimetic material (BM) technology. Carcinogenic embryonic antigen (CEA) was selected as target protein. The resulting BM-PPy film acted as biomimetic artificial antibody for CEA. Rebinding of CEA into this film changed its intrinsic electrical properties and the subsequent electrical output of the DSSC using it as CE. The quantity of CEA in solution was deduced by I-V and electrochemical impedance spesctroscopy (EIS). Linear responses to CEA were observed down to 0.25 pg/mL, with 0.13 pg/mL detection limit. Control films of PPy (prepared without CEA in the electropolymerization step) confirmed the ability of the BM material to recognize the target protein. Accurate results were obtained in the analysis of urine samples. Further developments into this ground-breaking self-powered biosensor will display a huge impact in point-to-care medical applications, which may be extended to other fields of knowledge.}, keywords = {}, pubstate = {published}, tppubtype = {article} } This work describes for the first time the integration of Dye Sensitized Solar Cell (DSSC) technology in biosensors and biomimetic materials, opening doors towards a new dimension of autonomous screening devices that may be used in point-of-care, with zero-power requirements. DSSCs are fabricated with a counter electrode (CE) of polypyrrole (PPy) that was made responsive to a specific protein by biomimetic material (BM) technology. Carcinogenic embryonic antigen (CEA) was selected as target protein. The resulting BM-PPy film acted as biomimetic artificial antibody for CEA. Rebinding of CEA into this film changed its intrinsic electrical properties and the subsequent electrical output of the DSSC using it as CE. The quantity of CEA in solution was deduced by I-V and electrochemical impedance spesctroscopy (EIS). Linear responses to CEA were observed down to 0.25 pg/mL, with 0.13 pg/mL detection limit. Control films of PPy (prepared without CEA in the electropolymerization step) confirmed the ability of the BM material to recognize the target protein. Accurate results were obtained in the analysis of urine samples. Further developments into this ground-breaking self-powered biosensor will display a huge impact in point-to-care medical applications, which may be extended to other fields of knowledge. |
Felismina T.C. Moreira, Blanca A.G. Rodriguez, Rosa A.F. Dutra, M. Goreti F. Sales Redox probe-free readings of a β-amyloid-42 plastic antibody sensory material assembled on copper@carbon nanotubes (Journal Article) Sensors and Actuators B: Chemical, 264 , pp. 1-9, 2018. @article{T.C.Moreira2018, title = {Redox probe-free readings of a β-amyloid-42 plastic antibody sensory material assembled on copper@carbon nanotubes}, author = {Felismina T.C. Moreira and Blanca A.G. Rodriguez and Rosa A.F. Dutra and M. Goreti F. Sales}, url = {https://www.sciencedirect.com/science/article/pii/S0925400518304519}, doi = {https://doi.org/10.1016/j.snb.2018.02.166}, year = {2018}, date = {2018-07-01}, journal = {Sensors and Actuators B: Chemical}, volume = {264}, pages = {1-9}, abstract = {This research work describes the synthesis of a new mediator-free electrochemical sensor, containing an electrochemically active ingredient at the carbon-working electrode. For this purpose, carbon nanotubes were modified with copper nanoparticles (CNT-CuO) and casted on the carbon-area. This electroactive film also acted as substrate to assemble the biorecognition element. As proof-of-concept, the 3-electrode system was made sensitive to the peptide β-amyloid42 (Aβ-42), by assembling a plastic antibody on top of the electroactive film. The plastic antibody was obtained by eletropolymerizing aniline (ANI) at neutral pH, under the presence of the template (Aβ-42). Next, the template molecule was removed from the polymeric network by acidic treatment. The vacant sites so obtained preserved the shape of the imprinted protein and were able to rebind new peptide molecules. SEM, XRD and RAMAN analysis were performed in order to control the surface modification of the carbon electrode. The ability of the biosensor to rebind Aβ-42 was monitored by square wave voltammetry (SWV). Redox peaks were centred at +0.4 V and peak currents decreased for an increasing concentration of Aβ-42. The reproducibility of the analytical signal was 8.37%, expressed in terms of the relative standard deviation (RSD, n = 3) of an Aβ-42 standard solution of 1.0 ng/mL. The detection limit was 0.4 (±0.03) pg/mL. The application of the device was tested in serum samples, spiked with Aβ-42 from 1.0 to 66.0 ng/mL. The obtained recovery data ranged from 88 to 93%. The greatest achievement of this work relates to the elimination of a redox probe reading-stage in electrochemical biosensing, by incorporating the electroactive element within the working electrode. Overall, this approach opens doors for direct sample readings, avoiding the incubation of active redox elements on the sensing area for analytical purposes. In addition, the developed biosensor showed excellent proprieties in terms of response time and simplicity, showing a remarkable potential for on-site application in medical research and clinical diagnosis.}, keywords = {}, pubstate = {published}, tppubtype = {article} } This research work describes the synthesis of a new mediator-free electrochemical sensor, containing an electrochemically active ingredient at the carbon-working electrode. For this purpose, carbon nanotubes were modified with copper nanoparticles (CNT-CuO) and casted on the carbon-area. This electroactive film also acted as substrate to assemble the biorecognition element. As proof-of-concept, the 3-electrode system was made sensitive to the peptide β-amyloid42 (Aβ-42), by assembling a plastic antibody on top of the electroactive film. The plastic antibody was obtained by eletropolymerizing aniline (ANI) at neutral pH, under the presence of the template (Aβ-42). Next, the template molecule was removed from the polymeric network by acidic treatment. The vacant sites so obtained preserved the shape of the imprinted protein and were able to rebind new peptide molecules. SEM, XRD and RAMAN analysis were performed in order to control the surface modification of the carbon electrode. The ability of the biosensor to rebind Aβ-42 was monitored by square wave voltammetry (SWV). Redox peaks were centred at +0.4 V and peak currents decreased for an increasing concentration of Aβ-42. The reproducibility of the analytical signal was 8.37%, expressed in terms of the relative standard deviation (RSD, n = 3) of an Aβ-42 standard solution of 1.0 ng/mL. The detection limit was 0.4 (±0.03) pg/mL. The application of the device was tested in serum samples, spiked with Aβ-42 from 1.0 to 66.0 ng/mL. The obtained recovery data ranged from 88 to 93%. The greatest achievement of this work relates to the elimination of a redox probe reading-stage in electrochemical biosensing, by incorporating the electroactive element within the working electrode. Overall, this approach opens doors for direct sample readings, avoiding the incubation of active redox elements on the sensing area for analytical purposes. In addition, the developed biosensor showed excellent proprieties in terms of response time and simplicity, showing a remarkable potential for on-site application in medical research and clinical diagnosis. |
Liliana A.A.N.A. Truta, Felismina T.C.Moreira, M. Goreti F.Sales A dye-sensitized solar cell acting as the electrical reading box of an immunosensor: Application to CEA determination (Journal Article) Biosensors and Bioelectronics, 107 , pp. 94-102, 2018. @article{Truta2018, title = {A dye-sensitized solar cell acting as the electrical reading box of an immunosensor: Application to CEA determination}, author = {Liliana A.A.N.A. Truta and Felismina T.C.Moreira and M. Goreti F.Sales}, url = {https://www.sciencedirect.com/science/article/pii/S095656631830099X?via%3Dihub}, doi = {https://doi.org/10.1016/j.bios.2018.02.011}, year = {2018}, date = {2018-06-01}, journal = {Biosensors and Bioelectronics}, volume = {107}, pages = {94-102}, abstract = {Monitoring cancer biomarkers in biological fluids has become a key tool for disease diagnosis, which should be of easy access anywhere in the world. The possibility of reducing basic requirements in the field of electrochemical biosensing may open doors in this direction. This work proposes for this purpose an innovative electrochemical immunosensing system using a photovoltaic cell as an electrical reading box. Immunosensing ensures accuracy, the electrochemical-ground of the device ensures sensitivity and detectability, and the photovoltaic cell drives the system towards electrical autonomy. As proof-of-concept, Carcinoembryonic antigen (CEA) was used herein, a cancer biomarker of clinical relevance. In brief, a conductive glass with a fluorine doped tin oxide film was used as conductive support and modified with anti-CEA by means of a bottom-up approach. All stages involved in the biochemical modification of the FTO surface were followed by electrochemical techniques, namely electrochemical impedance spectroscopy and cyclic voltammetry. This electrode acted as counter electrode of a dye-sensitized solar cells, and the electrical output of this cell was monitored for the different concentrations of CEA. Under optimized conditions, the device displayed a linear behaviour against CEA concentration, from 5 pg/mL to 15 ng/mL. The immunosensor was applied to the analysis of CEA in urine from healthy individual and spiked with the antigen. Overall, the presented approach demonstrates that photovoltaic cells may be employed as an electrical reading box of electrochemical biosensors, yielding a new direction towards autonomous electrochemical biosensing.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Monitoring cancer biomarkers in biological fluids has become a key tool for disease diagnosis, which should be of easy access anywhere in the world. The possibility of reducing basic requirements in the field of electrochemical biosensing may open doors in this direction. This work proposes for this purpose an innovative electrochemical immunosensing system using a photovoltaic cell as an electrical reading box. Immunosensing ensures accuracy, the electrochemical-ground of the device ensures sensitivity and detectability, and the photovoltaic cell drives the system towards electrical autonomy. As proof-of-concept, Carcinoembryonic antigen (CEA) was used herein, a cancer biomarker of clinical relevance. In brief, a conductive glass with a fluorine doped tin oxide film was used as conductive support and modified with anti-CEA by means of a bottom-up approach. All stages involved in the biochemical modification of the FTO surface were followed by electrochemical techniques, namely electrochemical impedance spectroscopy and cyclic voltammetry. This electrode acted as counter electrode of a dye-sensitized solar cells, and the electrical output of this cell was monitored for the different concentrations of CEA. Under optimized conditions, the device displayed a linear behaviour against CEA concentration, from 5 pg/mL to 15 ng/mL. The immunosensor was applied to the analysis of CEA in urine from healthy individual and spiked with the antigen. Overall, the presented approach demonstrates that photovoltaic cells may be employed as an electrical reading box of electrochemical biosensors, yielding a new direction towards autonomous electrochemical biosensing. |
G Cabral-Miranda, AR Cardoso, Luís CS Ferreira, M. Goreti F. Sales, M Bachmann Biosensor-based selective detection of Zika virus specific antibodies in infected individuals (Journal Article) Biosensors and Bioelectronics, 113 , pp. 101-107, 2018. @article{Cardoso.2018, title = {Biosensor-based selective detection of Zika virus specific antibodies in infected individuals}, author = {G Cabral-Miranda and AR Cardoso and Luís CS Ferreira and M. Goreti F. Sales and M Bachmann}, url = {https://doi.org/10.1016/j.bios.2018.04.058}, doi = {10.1016/j.bios.2018.04.058}, year = {2018}, date = {2018-05-01}, journal = {Biosensors and Bioelectronics}, volume = {113}, pages = {101-107}, abstract = {Zika virus (ZIKV) recently emerged as a global threat subsequent to its global spread because it induces microencephaly and other brain damages in infants born to infected mothers. Epidemiological monitoring of infection has been hampered by the absence of reliable serological tests capable to distinguish between ZIKV and other Flavivirus infections, in particular Dengue virus (DENV). As both viruses are transmitted by the same mosquito-species, their distributions largely overlap and reliable serological distinction between the viruses is essential. Here we develop a novel biosensor which is based on recombinant forms of ZIKV non-structural protein 1 (NS1) and the domain III of the envelope protein (EDIII). Using electrochemical impedance spectroscopy (EIS) and square wave voltammetry (SWV), we demonstrate that in addition to extremely sensitive detection of ZIKV-specific antibodies in serum and saliva, the biosensor promptly distinguished ZIKV and DENV-specific antibodies. Hence, this novel biosensor allows assessing ZIKV antibodies in blood and saliva and results are unaffected by presence of DENV virus-specific antibodies.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Zika virus (ZIKV) recently emerged as a global threat subsequent to its global spread because it induces microencephaly and other brain damages in infants born to infected mothers. Epidemiological monitoring of infection has been hampered by the absence of reliable serological tests capable to distinguish between ZIKV and other Flavivirus infections, in particular Dengue virus (DENV). As both viruses are transmitted by the same mosquito-species, their distributions largely overlap and reliable serological distinction between the viruses is essential. Here we develop a novel biosensor which is based on recombinant forms of ZIKV non-structural protein 1 (NS1) and the domain III of the envelope protein (EDIII). Using electrochemical impedance spectroscopy (EIS) and square wave voltammetry (SWV), we demonstrate that in addition to extremely sensitive detection of ZIKV-specific antibodies in serum and saliva, the biosensor promptly distinguished ZIKV and DENV-specific antibodies. Hence, this novel biosensor allows assessing ZIKV antibodies in blood and saliva and results are unaffected by presence of DENV virus-specific antibodies. |
R Gomes, Felismina T. C. Moreira, Rúben Fernandes, M. Goreti F. Sales Sensing CA 15-3 in point-of-care by electropolymerizing O-phenylenediamine (oPDA) on Au-screen printed electrodes (Journal Article) PLoS ONE, 13 (5), pp. e0196656, 2018. @article{Gomes2018, title = {Sensing CA 15-3 in point-of-care by electropolymerizing O-phenylenediamine (oPDA) on Au-screen printed electrodes}, author = {R Gomes and Felismina T. C. Moreira and Rúben Fernandes and M. Goreti F. Sales }, url = { https://doi.org/10.1371/journal.pone.0196656 }, doi = {10.1371/journal.pone.0196656}, year = {2018}, date = {2018-05-01}, journal = {PLoS ONE}, volume = {13}, number = {5}, pages = { e0196656}, abstract = {This work presents an alternative device for cancer screening in liquid biopsies. It combines a biomimetic film (i) with electrochemical detection (ii). The biomimetic film (i) was obtained by electro-polymerizing amine-substituted benzene rings around a CA 15–3 target. This protein target was previously adsorbed on a gold (Au) support and incubated in charged monomers (4-Styrenesulfonate sodium and 3-Hydroxytyraminium chloride). The protein was further eliminated by enzymatic activity, leaving behind vacant sites for subsequent rebinding. Electrochemical detection (ii) was achieved on an Au working electrode, designed on commercial screen-printed electrodes. Raman spectroscopy, atomic force microscopy and ellipsometric readings were used to follow the chemical modification of the Au surface. The ability of the material to rebind CA15-3 was monitored by electrochemical techniques. The device displayed linear responses to CA15-3 ranging from 0.25 to 10.00 U/mL, with detection limits of 0.05 U/mL. Accurate results were obtained by applying the sensor to the analysis of CA15-3 in PBS buffer and in serum samples. This biosensing device displayed successful features for the detection of CA 15–3 and constitutes a promising tool for breast cancer screening procedures in point-of-care applications. Moreover, its scale-up seems feasible as it contains a plastic antibody assembled in situ, in less than 1 minute, and the analysis of serum takes less than 30 minutes.}, keywords = {}, pubstate = {published}, tppubtype = {article} } This work presents an alternative device for cancer screening in liquid biopsies. It combines a biomimetic film (i) with electrochemical detection (ii). The biomimetic film (i) was obtained by electro-polymerizing amine-substituted benzene rings around a CA 15–3 target. This protein target was previously adsorbed on a gold (Au) support and incubated in charged monomers (4-Styrenesulfonate sodium and 3-Hydroxytyraminium chloride). The protein was further eliminated by enzymatic activity, leaving behind vacant sites for subsequent rebinding. Electrochemical detection (ii) was achieved on an Au working electrode, designed on commercial screen-printed electrodes. Raman spectroscopy, atomic force microscopy and ellipsometric readings were used to follow the chemical modification of the Au surface. The ability of the material to rebind CA15-3 was monitored by electrochemical techniques. The device displayed linear responses to CA15-3 ranging from 0.25 to 10.00 U/mL, with detection limits of 0.05 U/mL. Accurate results were obtained by applying the sensor to the analysis of CA15-3 in PBS buffer and in serum samples. This biosensing device displayed successful features for the detection of CA 15–3 and constitutes a promising tool for breast cancer screening procedures in point-of-care applications. Moreover, its scale-up seems feasible as it contains a plastic antibody assembled in situ, in less than 1 minute, and the analysis of serum takes less than 30 minutes. |
Ana Margarida Piloto, David S. M. Ribeiro, S. Sofia M. Rodrigues, Catarina Santos, João L. M. Santos, M.Goreti F. Sales Plastic antibodies tailored on quantum dots for an optical detection of myoglobin down to the femtomolar range (Journal Article) Scientific Reports, 8 (1), pp. 4944, 2018, ISSN: 2045-2322. @article{Piloto2018, title = {Plastic antibodies tailored on quantum dots for an optical detection of myoglobin down to the femtomolar range}, author = {Ana Margarida Piloto and David S. M. Ribeiro and S. Sofia M. Rodrigues and Catarina Santos and João L. M. Santos and M.Goreti F. Sales}, url = {https://www.nature.com/articles/s41598-018-23271-z}, doi = {10.1038/s41598-018-23271-z}, issn = {2045-2322}, year = {2018}, date = {2018-03-21}, journal = {Scientific Reports}, volume = {8}, number = {1}, pages = {4944}, abstract = {A highly sensitive fluorescence detection probe was developed by tailoring plastic antibodies on the external surface of aqueous soluble quantum dots (QDs). The target was Myoglobin (Myo), a cardiac biomarker that quenched the intrinsic fluorescent emission of cadmium telluride (CdTe) QDs capped with mercaptopropionic acid (CdTe-MPA-QDs). The QDs were incubated with the target protein and further modified with a molecularly-imprinted polymer (MIP) produced by radical polymerization of acrylamide and bisacrylamide. The main physical features of the materials were assessed by electron microscopy, dynamic light scattering (DLS), UV/Vis spectrophotometry and spectrofluorimetry. The plastic antibodies enabled Myo rebinding into the QDs with subsequent fluorescence quenching. This QD-probe could detect Myo concentrations from 0.304 to 571 pg/ml (50.6 fM to 95 pM), with a limit of detection of 0.045 pg/ml (7.6 fM). The proposed method was applied to the determination of Myo concentrations in synthetic human serum. The results obtained demonstrated the ability of the modified-QDs to determine Myo below the cut-off values of myocardial infarction. Overall, the nanostructured MIP-QDs reported herein displayed quick responses, good stability and sensitivity, and high selectivity for Myo, offering the potential to be explored as new emerging sensors for protein detection in human samples.}, keywords = {}, pubstate = {published}, tppubtype = {article} } A highly sensitive fluorescence detection probe was developed by tailoring plastic antibodies on the external surface of aqueous soluble quantum dots (QDs). The target was Myoglobin (Myo), a cardiac biomarker that quenched the intrinsic fluorescent emission of cadmium telluride (CdTe) QDs capped with mercaptopropionic acid (CdTe-MPA-QDs). The QDs were incubated with the target protein and further modified with a molecularly-imprinted polymer (MIP) produced by radical polymerization of acrylamide and bisacrylamide. The main physical features of the materials were assessed by electron microscopy, dynamic light scattering (DLS), UV/Vis spectrophotometry and spectrofluorimetry. The plastic antibodies enabled Myo rebinding into the QDs with subsequent fluorescence quenching. This QD-probe could detect Myo concentrations from 0.304 to 571 pg/ml (50.6 fM to 95 pM), with a limit of detection of 0.045 pg/ml (7.6 fM). The proposed method was applied to the determination of Myo concentrations in synthetic human serum. The results obtained demonstrated the ability of the modified-QDs to determine Myo below the cut-off values of myocardial infarction. Overall, the nanostructured MIP-QDs reported herein displayed quick responses, good stability and sensitivity, and high selectivity for Myo, offering the potential to be explored as new emerging sensors for protein detection in human samples. |
J.A. Ribeiroa, C.M. Pereiraa, A.F. Silvaa, M.Goreti F. Sales Disposable electrochemical detection of breast cancer tumour marker CA 15-3 using poly(Toluidine Blue) as imprinted polymer receptor (Journal Article) Biosensors and Bioelectronics, 2018. @article{Ribeiroa2018, title = {Disposable electrochemical detection of breast cancer tumour marker CA 15-3 using poly(Toluidine Blue) as imprinted polymer receptor}, author = {J.A. Ribeiroa and C.M. Pereiraa and A.F. Silvaa and M.Goreti F. Sales}, url = {https://www.sciencedirect.com/science/article/pii/S095656631830174X}, doi = {https://doi.org/10.1016/j.bios.2018.03.011}, year = {2018}, date = {2018-03-08}, journal = {Biosensors and Bioelectronics}, abstract = {In this work, electrically-conducting poly(Toludine Blue) was employed for the first time as synthetic receptor film, prepared by Molecular Imprinting strategies and using electrochemical methods, for the specific screening of breast cancer biomarker Carbohydrate Antigen 15-3 (CA 15-3). The protein imprinted poly(Toluidine Blue) film was grown in a pre-formed Toluidine Blue (TB) tailed SAM at the AuSPE surface, which greatly enhanced the stability against degradation of the Molecular Imprinted Polymer (MIP) film at the electrode surface. The MIP receptor film recognition ability towards the protein was investigated by fitting data to Freundlich isotherm. The binding affinity (KF) obtained for the MIP system was significantly higher (~12-fold) to that obtained for the NIP system, demonstrating the success of the approach in creating imprinted materials that specifically respond to CA 15-3 protein. The incubation of the MIP modified electrode with increasing concentration of protein (from 0.10 U mL−1 to 1000 U mL−1) resulted in a decrease of the ferro/ferricyanide redox current. The device displayed linear response from 0.10 U mL−1 to 100 U mL−1 and LODs below 0.10 U mL−1 were obtained from calibration curves built in neutral buffer and diluted artificial serum, using DPV technique, enabling the detection of the protein biomarker at clinically relevant levels. The developed MIP biosensor was applied to the determination of CA 15-3 in spiked serum samples with satisfactory results. The developed device provides a new strategy for sensitive, rapid, simple and cost-effective screening of CA 15-3 biomarker. Importantly, the overall approach seems suitable for point-of-care (PoC) use in clinical context.}, keywords = {}, pubstate = {published}, tppubtype = {article} } In this work, electrically-conducting poly(Toludine Blue) was employed for the first time as synthetic receptor film, prepared by Molecular Imprinting strategies and using electrochemical methods, for the specific screening of breast cancer biomarker Carbohydrate Antigen 15-3 (CA 15-3). The protein imprinted poly(Toluidine Blue) film was grown in a pre-formed Toluidine Blue (TB) tailed SAM at the AuSPE surface, which greatly enhanced the stability against degradation of the Molecular Imprinted Polymer (MIP) film at the electrode surface. The MIP receptor film recognition ability towards the protein was investigated by fitting data to Freundlich isotherm. The binding affinity (KF) obtained for the MIP system was significantly higher (~12-fold) to that obtained for the NIP system, demonstrating the success of the approach in creating imprinted materials that specifically respond to CA 15-3 protein. The incubation of the MIP modified electrode with increasing concentration of protein (from 0.10 U mL−1 to 1000 U mL−1) resulted in a decrease of the ferro/ferricyanide redox current. The device displayed linear response from 0.10 U mL−1 to 100 U mL−1 and LODs below 0.10 U mL−1 were obtained from calibration curves built in neutral buffer and diluted artificial serum, using DPV technique, enabling the detection of the protein biomarker at clinically relevant levels. The developed MIP biosensor was applied to the determination of CA 15-3 in spiked serum samples with satisfactory results. The developed device provides a new strategy for sensitive, rapid, simple and cost-effective screening of CA 15-3 biomarker. Importantly, the overall approach seems suitable for point-of-care (PoC) use in clinical context. |
Alexandra R. T. Santos, Felismina T. C. Moreira, Luísa A. Helguero, M. Goreti F. Sales Antibody Biomimetic Material Made of Pyrrole for CA 15-3 and Its Application as Sensing Material in Ion-Selective Electrodes for Potentiometric Detection (Journal Article) Biosensors, 8 , 2018. @article{Santos2018, title = {Antibody Biomimetic Material Made of Pyrrole for CA 15-3 and Its Application as Sensing Material in Ion-Selective Electrodes for Potentiometric Detection}, author = {Alexandra R. T. Santos and Felismina T. C. Moreira and Luísa A. Helguero and M. Goreti F. Sales}, url = {http://www.mdpi.com/2079-6374/8/1/8}, doi = {10.3390/bios8010008}, year = {2018}, date = {2018-01-19}, journal = {Biosensors}, volume = {8}, abstract = {This work reports a very simple approach for creating a synthetic antibody against any protein of interest and its application in potentiometric transduction. The selected protein was Breast Cancer Antigen (CA 15-3), which is implicated in breast cancer disease and used to follow-up breast cancer patients during treatment. The new material with antibody-like properties was obtained by molecular-imprinting technology, prepared by electropolymerizing pyrrol (Py, 5.0 × 10−3 mol/L) around Breast Cancer Antigen (CA 15-3) (100 U/mL) on a fluorine doped tin oxide (FTO) conductive glass support. Cyclic voltammetry was employed for this purpose. All solutions were prepared in 4-(2-Hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES) buffer, of pH 6.5. The biomarker was removed from the imprinted sites by chemical action of ethanol. The biomimetic material was then included in poly vinyl chloride (PVC) plasticized membranes to act as potentiometric ionophore, having or not a lipophilic ionic additive added. The corresponding selective electrodes were evaluated by calibration curves (in buffer and in synthetic serum) and by selectivity testing. The best analytical performance was obtained by selective electrodes including the plastic antibody and no lipophilic additive. The average limits of detection were 1.07 U/mL of CA 15-3, with a linear response from 1.44 to 13.2 U/mL and a cationic slope of 44.5 mV/decade. Overall, the lipophilic additives yielded no advantage to the overall potentiometric performance. The application of the MIP-based electrodes to the analysis of spiked synthetic serum showed precise and accurate results}, keywords = {}, pubstate = {published}, tppubtype = {article} } This work reports a very simple approach for creating a synthetic antibody against any protein of interest and its application in potentiometric transduction. The selected protein was Breast Cancer Antigen (CA 15-3), which is implicated in breast cancer disease and used to follow-up breast cancer patients during treatment. The new material with antibody-like properties was obtained by molecular-imprinting technology, prepared by electropolymerizing pyrrol (Py, 5.0 × 10−3 mol/L) around Breast Cancer Antigen (CA 15-3) (100 U/mL) on a fluorine doped tin oxide (FTO) conductive glass support. Cyclic voltammetry was employed for this purpose. All solutions were prepared in 4-(2-Hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES) buffer, of pH 6.5. The biomarker was removed from the imprinted sites by chemical action of ethanol. The biomimetic material was then included in poly vinyl chloride (PVC) plasticized membranes to act as potentiometric ionophore, having or not a lipophilic ionic additive added. The corresponding selective electrodes were evaluated by calibration curves (in buffer and in synthetic serum) and by selectivity testing. The best analytical performance was obtained by selective electrodes including the plastic antibody and no lipophilic additive. The average limits of detection were 1.07 U/mL of CA 15-3, with a linear response from 1.44 to 13.2 U/mL and a cationic slope of 44.5 mV/decade. Overall, the lipophilic additives yielded no advantage to the overall potentiometric performance. The application of the MIP-based electrodes to the analysis of spiked synthetic serum showed precise and accurate results |
2017
APM Tavares, MGF Sales Novel electro-polymerized protein-imprinted materials using Eriochrome black T: Application to BSA sensing (Journal Article) Electrochimica Acta, 2017. @article{Tavares2017b, title = {Novel electro-polymerized protein-imprinted materials using Eriochrome black T: Application to BSA sensing}, author = {APM Tavares and MGF Sales}, url = {https://www.sciencedirect.com/science/article/pii/S0013468617327652}, doi = {10.1016/j.electacta.2017.12.191}, year = {2017}, date = {2017-12-31}, journal = {Electrochimica Acta}, abstract = {A novel material produced in-situ by electropolymerization of Eriochrome black T (EBT) is presented for the first time to produce a molecularly-imprinted polymer (MIP) tailored for protein recognition. This monomer is particularly useful because it contains in the same structure different functions that may interact with different sites within the same protein (by ionic interaction of hydrogen bonding). The polymer was poly(EBT) (PEBT) and was obtained by applying on a carbon support a suitable range of potential values, established by cyclic voltammetry (CV) along consecutive cycles. In a parallel approach, the carbon support was modified by electropolymerizing 3,4-ethylenedioxythiophene (EDOT) prior to the MIP synthesis, thereby yielding a substrate of better electrical properties and checking this effect upon the resulting biosensor. The two above approaches used BSA as model target protein. The polymeric material acted as a plastic antibody for BSA and was obtained through a bulk imprinting strategy, by electropolymerizing EBT in a solution that also contained the target protein. The chemical features were followed by Raman spectroscopy while the electrical properties were followed by electrochemical impedance spectroscopy (EIS). The electrical properties tested were the stability of polymeric film within time, the main analytical features of the calibration curves under different media and the selectivity properties. The thermal stability was also tested by thermogravimetric assays. Overall, the novel polymeric film displayed good thermal and storage stabilities, which are fundamental features in biosensor development. Both MIP and MIP-PEDOT displayed linear responses over a wide range of concentrations and similar detection limits. The MIP-PEDOT material was 9 × more sensitive to the presence BSA concentration. The analytical responses of the biosensor to spiked serum confirms the promising features of the described approach.}, keywords = {}, pubstate = {published}, tppubtype = {article} } A novel material produced in-situ by electropolymerization of Eriochrome black T (EBT) is presented for the first time to produce a molecularly-imprinted polymer (MIP) tailored for protein recognition. This monomer is particularly useful because it contains in the same structure different functions that may interact with different sites within the same protein (by ionic interaction of hydrogen bonding). The polymer was poly(EBT) (PEBT) and was obtained by applying on a carbon support a suitable range of potential values, established by cyclic voltammetry (CV) along consecutive cycles. In a parallel approach, the carbon support was modified by electropolymerizing 3,4-ethylenedioxythiophene (EDOT) prior to the MIP synthesis, thereby yielding a substrate of better electrical properties and checking this effect upon the resulting biosensor. The two above approaches used BSA as model target protein. The polymeric material acted as a plastic antibody for BSA and was obtained through a bulk imprinting strategy, by electropolymerizing EBT in a solution that also contained the target protein. The chemical features were followed by Raman spectroscopy while the electrical properties were followed by electrochemical impedance spectroscopy (EIS). The electrical properties tested were the stability of polymeric film within time, the main analytical features of the calibration curves under different media and the selectivity properties. The thermal stability was also tested by thermogravimetric assays. Overall, the novel polymeric film displayed good thermal and storage stabilities, which are fundamental features in biosensor development. Both MIP and MIP-PEDOT displayed linear responses over a wide range of concentrations and similar detection limits. The MIP-PEDOT material was 9 × more sensitive to the presence BSA concentration. The analytical responses of the biosensor to spiked serum confirms the promising features of the described approach. |
Mariana C.C.G.Carneiro, Felismina T.C.Moreira, Rosa A.F.Dutra, RúbenFernandes, M. Goreti F.Sales Homemade 3-carbon electrode system for electrochemical sensing: Application to microRNA detection (Journal Article) Microchemical Journal, 138 , pp. 35-44, 2017. @article{C.C.G.Carneiro2017, title = {Homemade 3-carbon electrode system for electrochemical sensing: Application to microRNA detection}, author = {Mariana C.C.G.Carneiro and Felismina T.C.Moreira and Rosa A.F.Dutra and RúbenFernandes and M. Goreti F.Sales}, url = {https://www.sciencedirect.com/science/article/pii/S0026265X17307294}, doi = {10.1016/j.microc.2017.12.026}, year = {2017}, date = {2017-12-29}, journal = {Microchemical Journal}, volume = {138}, pages = {35-44}, abstract = {The homemade production of carbon screen-printed electrodes (C-SPEs) with a three‑carbon electrode system is reported, along with its application in electrochemical sensing. It is highlighted herein as main novelty that a simple carbon ink may be employed in the preparation of the 3-electrode system, including the pseudo-reference electrode, thereby avoiding the addition of silver or other suitable metal and simplify the construction of such devices, reducing costs and time. Screen-printed technology was employed to produce the 3-electrodes and the corresponding electrical paths. This was achieved by the manual application of a commercial carbon ink into a polyvinyl chloride (PVC) substrate allowing the production of > 20 SPEs. The optimization of the SPE assembly was made by univariate mode, until the best electrical features of the electrode-solution interface were achieved. Several electrochemical techniques were used for this purpose, namely cyclic voltammetry (CV), square wave voltammetry (SWV) and electrochemical impedance spectroscopy (EIS). Raman Spectroscopy and Thermogravimetric Analysis (TGA) were also used for materials and electrode surface characterization. The usefulness of such devices was tested by modifying the working electrode with a sensing layer for microRNA-107, a potential biomarker in Alzheimer's Disease (AD). For this purpose, the surface was functionalized with carboxylic groups, activated by carbodiimide reaction and bound to a suitable oligonucleotide probe containing the complementary sequence. Finally, the microRNA-107 sequence hybridized with its probe, proving the efficiency of the C-SPEs in electrochemical sensing. Overall, this study brings into light the possibility of preparing simple homemade electrodes with a 3‑carbon electrode system that stands out by the low cost, disposability and versatility of the presented platform, holding a great potential for application in point-of-care devices using electrochemical sensing.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The homemade production of carbon screen-printed electrodes (C-SPEs) with a three‑carbon electrode system is reported, along with its application in electrochemical sensing. It is highlighted herein as main novelty that a simple carbon ink may be employed in the preparation of the 3-electrode system, including the pseudo-reference electrode, thereby avoiding the addition of silver or other suitable metal and simplify the construction of such devices, reducing costs and time. Screen-printed technology was employed to produce the 3-electrodes and the corresponding electrical paths. This was achieved by the manual application of a commercial carbon ink into a polyvinyl chloride (PVC) substrate allowing the production of > 20 SPEs. The optimization of the SPE assembly was made by univariate mode, until the best electrical features of the electrode-solution interface were achieved. Several electrochemical techniques were used for this purpose, namely cyclic voltammetry (CV), square wave voltammetry (SWV) and electrochemical impedance spectroscopy (EIS). Raman Spectroscopy and Thermogravimetric Analysis (TGA) were also used for materials and electrode surface characterization. The usefulness of such devices was tested by modifying the working electrode with a sensing layer for microRNA-107, a potential biomarker in Alzheimer's Disease (AD). For this purpose, the surface was functionalized with carboxylic groups, activated by carbodiimide reaction and bound to a suitable oligonucleotide probe containing the complementary sequence. Finally, the microRNA-107 sequence hybridized with its probe, proving the efficiency of the C-SPEs in electrochemical sensing. Overall, this study brings into light the possibility of preparing simple homemade electrodes with a 3‑carbon electrode system that stands out by the low cost, disposability and versatility of the presented platform, holding a great potential for application in point-of-care devices using electrochemical sensing. |
Mariana C.C.G.Carneiro, Felismina T. C. Moreira, Rosa A.F. Dutra, Rúben Fernandes, M. Goreti F. Sales Homemade 3-carbon electrode system for electrochemical sensing: Application to microRNA detection (Journal Article) Microchemical Journal, 138 , pp. 35-44, 2017. @article{Mariana2018, title = {Homemade 3-carbon electrode system for electrochemical sensing: Application to microRNA detection}, author = {Mariana C.C.G.Carneiro and Felismina T. C. Moreira and Rosa A.F. Dutra and Rúben Fernandes and M. Goreti F. Sales}, url = {https://doi.org/10.1016/j.microc.2017.12.026}, doi = {10.1016/j.microc.2017.12.026}, year = {2017}, date = {2017-12-27}, journal = {Microchemical Journal}, volume = {138}, pages = {35-44}, abstract = {The homemade production of carbon screen-printed electrodes (C-SPEs) with a three‑carbon electrode system is reported, along with its application in electrochemical sensing. It is highlighted herein as main novelty that a simple carbon ink may be employed in the preparation of the 3-electrode system, including the pseudo-reference electrode, thereby avoiding the addition of silver or other suitable metal and simplify the construction of such devices, reducing costs and time. Screen-printed technology was employed to produce the 3-electrodes and the corresponding electrical paths. This was achieved by the manual application of a commercial carbon ink into a polyvinyl chloride (PVC) substrate allowing the production of > 20 SPEs. The optimization of the SPE assembly was made by univariate mode, until the best electrical features of the electrode-solution interface were achieved. Several electrochemical techniques were used for this purpose, namely cyclic voltammetry (CV), square wave voltammetry (SWV) and electrochemical impedance spectroscopy (EIS). Raman Spectroscopy and Thermogravimetric Analysis (TGA) were also used for materials and electrode surface characterization. The usefulness of such devices was tested by modifying the working electrode with a sensing layer for microRNA-107, a potential biomarker in Alzheimer's Disease (AD). For this purpose, the surface was functionalized with carboxylic groups, activated by carbodiimide reaction and bound to a suitable oligonucleotide probe containing the complementary sequence. Finally, the microRNA-107 sequence hybridized with its probe, proving the efficiency of the C-SPEs in electrochemical sensing. Overall, this study brings into light the possibility of preparing simple homemade electrodes with a 3‑carbon electrode system that stands out by the low cost, disposability and versatility of the presented platform, holding a great potential for application in point-of-care devices using electrochemical sensing.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The homemade production of carbon screen-printed electrodes (C-SPEs) with a three‑carbon electrode system is reported, along with its application in electrochemical sensing. It is highlighted herein as main novelty that a simple carbon ink may be employed in the preparation of the 3-electrode system, including the pseudo-reference electrode, thereby avoiding the addition of silver or other suitable metal and simplify the construction of such devices, reducing costs and time. Screen-printed technology was employed to produce the 3-electrodes and the corresponding electrical paths. This was achieved by the manual application of a commercial carbon ink into a polyvinyl chloride (PVC) substrate allowing the production of > 20 SPEs. The optimization of the SPE assembly was made by univariate mode, until the best electrical features of the electrode-solution interface were achieved. Several electrochemical techniques were used for this purpose, namely cyclic voltammetry (CV), square wave voltammetry (SWV) and electrochemical impedance spectroscopy (EIS). Raman Spectroscopy and Thermogravimetric Analysis (TGA) were also used for materials and electrode surface characterization. The usefulness of such devices was tested by modifying the working electrode with a sensing layer for microRNA-107, a potential biomarker in Alzheimer's Disease (AD). For this purpose, the surface was functionalized with carboxylic groups, activated by carbodiimide reaction and bound to a suitable oligonucleotide probe containing the complementary sequence. Finally, the microRNA-107 sequence hybridized with its probe, proving the efficiency of the C-SPEs in electrochemical sensing. Overall, this study brings into light the possibility of preparing simple homemade electrodes with a 3‑carbon electrode system that stands out by the low cost, disposability and versatility of the presented platform, holding a great potential for application in point-of-care devices using electrochemical sensing. |
AR Cardoso, APM Tavares, M. Goreti F. Sales In-situ generated molecularly imprinted material for chloramphenicol electrochemical sensing in waters down to the nanomolar level (Journal Article) Sensors and Actuators B: Chemical, 256 , pp. 420-428, 2017. @article{Cardoso2018, title = {In-situ generated molecularly imprinted material for chloramphenicol electrochemical sensing in waters down to the nanomolar level}, author = {AR Cardoso and APM Tavares and M. Goreti F. Sales }, url = {https://doi.org/10.1016/j.snb.2017.10.114}, doi = {10.1016/j.snb.2017.10.114}, year = {2017}, date = {2017-11-20}, journal = {Sensors and Actuators B: Chemical}, volume = {256}, pages = {420-428}, abstract = {A novel device for monitoring chloramphenicol (CAP) on-site is described, making use of commercial carbon screen-printed electrodes (C-SPEs) modified with a suitable sensing element. This element consisted of a molecularly imprinted polymer (MIP), produced in-situ, by electro-polymerization. The monomers used herein were Eriochrome black T (EBT), and polymerization was conducted in acetonitrile. Raman spectroscopy followed the chemical changes occurring at each stage of the carbon surface modification. The device performance was assessed by evaluating the changes in electron transfer properties of a standard redox probe [Fe(CN)6]3−/[Fe(CN)6]4− by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and square wave voltammetry (SWV). SWV and EIS electrochemical techniques were used to calibrate the system, having standard solutions prepared under different background media (electrolyte or water coming from a home fish tank). A wide linear range was observed, with linear responses of current/resistance against log (CAP concentration) down to 10 nM. Overall, the results obtained revealed that all modifications carried out on the sensing element were effective. The final sensor provided reproducible and accurate readings and was all assembled in-situ, in a very simple and straightforward approach, most likely suitable for scaling-up, directing towards its subsequent commercial use.}, keywords = {}, pubstate = {published}, tppubtype = {article} } A novel device for monitoring chloramphenicol (CAP) on-site is described, making use of commercial carbon screen-printed electrodes (C-SPEs) modified with a suitable sensing element. This element consisted of a molecularly imprinted polymer (MIP), produced in-situ, by electro-polymerization. The monomers used herein were Eriochrome black T (EBT), and polymerization was conducted in acetonitrile. Raman spectroscopy followed the chemical changes occurring at each stage of the carbon surface modification. The device performance was assessed by evaluating the changes in electron transfer properties of a standard redox probe [Fe(CN)6]3−/[Fe(CN)6]4− by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and square wave voltammetry (SWV). SWV and EIS electrochemical techniques were used to calibrate the system, having standard solutions prepared under different background media (electrolyte or water coming from a home fish tank). A wide linear range was observed, with linear responses of current/resistance against log (CAP concentration) down to 10 nM. Overall, the results obtained revealed that all modifications carried out on the sensing element were effective. The final sensor provided reproducible and accurate readings and was all assembled in-situ, in a very simple and straightforward approach, most likely suitable for scaling-up, directing towards its subsequent commercial use. |
GV Martins, APM Tavares, E Fortunato, MGF Sales Paper-based sensing device for electrochemical detection of oxidative stress biomarker 8-hydroxy-2′-deoxyguanosine (8-OHdG) in point-of-care (Journal Article) Scientific Reports, 7 , pp. 14558, 2017. @article{Martins2017b, title = {Paper-based sensing device for electrochemical detection of oxidative stress biomarker 8-hydroxy-2′-deoxyguanosine (8-OHdG) in point-of-care}, author = {GV Martins and APM Tavares and E Fortunato and MGF Sales}, url = {https://www.nature.com/articles/s41598-017-14878-9}, doi = {10.1038/s41598-017-14878-9}, year = {2017}, date = {2017-11-06}, journal = {Scientific Reports}, volume = {7}, pages = {14558}, abstract = {This work presents a cost-effective, label-free in point-of-care (POC) biosensor for the sensitive detection of 8-hydroxy-2′-deoxyguanosine (8-OHdG), the most abundant oxidative product of DNA, that may allow a premature assessment of cancer disease, thereby improving diagnosis, prognostics and survival rates. The device targets the direct detection of 8-OHdG by using for the first time a carbon-ink 3-electrode on a paper substrate coupled to Differential Pulse Voltammetry readings. This design was optimized by adding nanostructured carbon materials to the ink and the conducting polymer PEDOT, enhancing the electrocatalytic properties of the sensor towards 8-OHdG detection. Meanwhile, the ability of this oxidative stress biomarker to undertake an oxidation reaction enabled the development of the sensing electrochemical device without the need of chemical probes and long incubation periods. This paper-modified sensor presented high electrochemical performance on the oxidation of 8-OHdG with a wide linear range (50–1000 ng/ml) and a low detection limit (14.4 ng/ml). Thus, our results showed the development of a direct and facile sensor with good reproducibility, stability, sensitivity and more importantly, selectivity. The proposed carbon-based electrochemical sensor is a potential candidate to be miniaturized to small portable size, which make it applicable for in-situ 8-OHdG sensing in real biological samples.}, keywords = {}, pubstate = {published}, tppubtype = {article} } This work presents a cost-effective, label-free in point-of-care (POC) biosensor for the sensitive detection of 8-hydroxy-2′-deoxyguanosine (8-OHdG), the most abundant oxidative product of DNA, that may allow a premature assessment of cancer disease, thereby improving diagnosis, prognostics and survival rates. The device targets the direct detection of 8-OHdG by using for the first time a carbon-ink 3-electrode on a paper substrate coupled to Differential Pulse Voltammetry readings. This design was optimized by adding nanostructured carbon materials to the ink and the conducting polymer PEDOT, enhancing the electrocatalytic properties of the sensor towards 8-OHdG detection. Meanwhile, the ability of this oxidative stress biomarker to undertake an oxidation reaction enabled the development of the sensing electrochemical device without the need of chemical probes and long incubation periods. This paper-modified sensor presented high electrochemical performance on the oxidation of 8-OHdG with a wide linear range (50–1000 ng/ml) and a low detection limit (14.4 ng/ml). Thus, our results showed the development of a direct and facile sensor with good reproducibility, stability, sensitivity and more importantly, selectivity. The proposed carbon-based electrochemical sensor is a potential candidate to be miniaturized to small portable size, which make it applicable for in-situ 8-OHdG sensing in real biological samples. |
AR Cardoso, APM Tavares, MGF Sales In-situ generated molecularly imprinted material for chloramphenicol electrochemical sensing in waters down to the nanomolar level (Journal Article) Sensors and Actuators B: Chemical, 256 , pp. 420-428, 2017. @article{Cardoso2017b, title = {In-situ generated molecularly imprinted material for chloramphenicol electrochemical sensing in waters down to the nanomolar level}, author = {AR Cardoso and APM Tavares and MGF Sales}, url = {http://www.sciencedirect.com/science/article/pii/S0925400517320166}, doi = {10.1016/j.snb.2017.10.114}, year = {2017}, date = {2017-10-20}, journal = {Sensors and Actuators B: Chemical}, volume = {256}, pages = {420-428}, abstract = {A novel device for monitoring chloramphenicol (CAP) on-site is described, making use of commercial carbon screen-printed electrodes (C-SPEs) modified with a suitable sensing element. This element consisted of a molecularly imprinted polymer (MIP), produced in-situ, by electro-polymerization. The monomers used herein were Eriochrome black T (EBT), and polymerization was conducted in acetonitrile. Raman spectroscopy followed the chemical changes occurring at each stage of the carbon surface modification. The device performance was assessed by evaluating the changes in electron transfer properties of a standard redox probe [Fe(CN)6]3−/[Fe(CN)6]4− by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and square wave voltammetry (SWV). SWV and EIS electrochemical techniques were used to calibrate the system, having standard solutions prepared under different background media (electrolyte or water coming from a home fish tank). A wide linear range was observed, with linear responses of current/resistance against log (CAP concentration) down to 10 nM. Overall, the results obtained revealed that all modifications carried out on the sensing element were effective. The final sensor provided reproducible and accurate readings and was all assembled in-situ, in a very simple and straightforward approach, most likely suitable for scaling-up, directing towards its subsequent commercial use.}, keywords = {}, pubstate = {published}, tppubtype = {article} } A novel device for monitoring chloramphenicol (CAP) on-site is described, making use of commercial carbon screen-printed electrodes (C-SPEs) modified with a suitable sensing element. This element consisted of a molecularly imprinted polymer (MIP), produced in-situ, by electro-polymerization. The monomers used herein were Eriochrome black T (EBT), and polymerization was conducted in acetonitrile. Raman spectroscopy followed the chemical changes occurring at each stage of the carbon surface modification. The device performance was assessed by evaluating the changes in electron transfer properties of a standard redox probe [Fe(CN)6]3−/[Fe(CN)6]4− by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and square wave voltammetry (SWV). SWV and EIS electrochemical techniques were used to calibrate the system, having standard solutions prepared under different background media (electrolyte or water coming from a home fish tank). A wide linear range was observed, with linear responses of current/resistance against log (CAP concentration) down to 10 nM. Overall, the results obtained revealed that all modifications carried out on the sensing element were effective. The final sensor provided reproducible and accurate readings and was all assembled in-situ, in a very simple and straightforward approach, most likely suitable for scaling-up, directing towards its subsequent commercial use. |
MGF Sales, L Brandão Autonomous electrochemical biosensors: a new vision to direct methanol fuel cells (Journal Article) Biosensors and Bioelectronics, 98 , pp. 428-436, 2017. @article{Sales2017, title = {Autonomous electrochemical biosensors: a new vision to direct methanol fuel cells}, author = {MGF Sales and L Brandão}, url = {http://www.sciencedirect.com/science/article/pii/S0956566317304694}, doi = {10.1016/j.bios.2017.07.021}, year = {2017}, date = {2017-07-11}, journal = {Biosensors and Bioelectronics}, volume = {98}, pages = {428-436}, abstract = {A new approach to biosensing devices is demonstrated aiming an easier and simpler application in routine health care systems. Our methodology considered a new concept for the biosensor transducing event that allows to obtain, simultaneously, an equipment-free, user-friendly, cheap electrical biosensor. The use of the anode triple-phase boundary (TPB) layer of a passive direct methanol fuel cell (DMFC) as biosensor transducer is herein proposed. For that, the ionomer present in the anode catalytic layer of the DMFC is partially replaced by an ionomer with molecular recognition capability working as the biorecognition element of the biosensor. In this approach, fuel cell anode catalysts are modified with a molecularly imprinted polymer (plastic antibody) capable of protein recognition (ferritin is used as model protein), inserted in a suitable membrane electrode assembly (MEA) and tested, as initial proof-of-concept, in a non-passive fuel cell operation environment. The anchoring of the ionomer-based plastic antibody on the catalyst surface follows a simple one-step grafting from approach through radical polymerization. Such modification increases fuel cell performance due to the proton conductivity and macroporosity characteristics of the polymer on the TPB. Finally, the response and selectivity of the bioreceptor inside the fuel cell showed a clear and selective signal from the biosensor. Moreover, such pioneering transducing approach allowed amplification of the electrochemical response and increased biosensor sensitivity by 2 orders of magnitude when compared to a 3-electrodes configuration system.}, keywords = {}, pubstate = {published}, tppubtype = {article} } A new approach to biosensing devices is demonstrated aiming an easier and simpler application in routine health care systems. Our methodology considered a new concept for the biosensor transducing event that allows to obtain, simultaneously, an equipment-free, user-friendly, cheap electrical biosensor. The use of the anode triple-phase boundary (TPB) layer of a passive direct methanol fuel cell (DMFC) as biosensor transducer is herein proposed. For that, the ionomer present in the anode catalytic layer of the DMFC is partially replaced by an ionomer with molecular recognition capability working as the biorecognition element of the biosensor. In this approach, fuel cell anode catalysts are modified with a molecularly imprinted polymer (plastic antibody) capable of protein recognition (ferritin is used as model protein), inserted in a suitable membrane electrode assembly (MEA) and tested, as initial proof-of-concept, in a non-passive fuel cell operation environment. The anchoring of the ionomer-based plastic antibody on the catalyst surface follows a simple one-step grafting from approach through radical polymerization. Such modification increases fuel cell performance due to the proton conductivity and macroporosity characteristics of the polymer on the TPB. Finally, the response and selectivity of the bioreceptor inside the fuel cell showed a clear and selective signal from the biosensor. Moreover, such pioneering transducing approach allowed amplification of the electrochemical response and increased biosensor sensitivity by 2 orders of magnitude when compared to a 3-electrodes configuration system. |
JA Ribeiro, CM Pereira, AF Silva, MGF Sales Electrochemical detection of cardiac biomarker myoglobin using polyphenol as imprinted polymer receptor (Journal Article) Analytica Chimica Acta, 981 , pp. 41-52, 2017. @article{Ribeiro2017, title = {Electrochemical detection of cardiac biomarker myoglobin using polyphenol as imprinted polymer receptor}, author = {JA Ribeiro and CM Pereira and AF Silva and MGF Sales}, url = {http://www.sciencedirect.com/science/article/pii/S0003267017306694?via%3Dihub}, doi = {10.1016/j.aca.2017.05.017}, year = {2017}, date = {2017-06-02}, journal = {Analytica Chimica Acta}, volume = {981}, pages = {41-52}, abstract = {An electrochemical biosensor was developed by merging the features of Molecular Imprinting technique and Screen-Printed Electrode (SPE) for the simple and fast screening of cardiac biomarker myoglobin (Myo) in point-of-care (POC). The MIP artificial receptor for Myo was prepared by electrooxidative polymerization of phenol (Ph) on a AuSPE in the presence of Myo as template molecule. The choice of the most effective protein extraction procedure from the various extraction methods tested (mildly acidic/basic solutions, pure/mixed organic solvents, solutions containing surfactants and enzymatic digestion methods), and the optimization of the thickness of the polymer film was carefully undertaken in order to improve binding characteristics of Myo to the imprinted polymer receptor and increase the sensitivity of the MIP biosensor. The film thickness was optimized by adjusting scan rate and the number of cycles during cyclic voltammetric electropolymerization of Ph. The thickness of the polyphenol nanocoating of only few nanometres (~4.4 nm), and similar to the protein diameter, brought in significant improvements in terms of sensor sensitivity. The binding affinity of MIP receptor film was estimated by fitting the experimental data to Freundlich isotherm and a ~8 fold increase in the binding affinity of Myo to the imprinted polymer (KF = 0.119 ± 0.002 ng/mL) when compared to the non-imprinted polymer (KF= 0.015 ± 0.002 ng/mL) which demonstrated excellent (re)binding affinity for the imprinted protein. }, keywords = {}, pubstate = {published}, tppubtype = {article} } An electrochemical biosensor was developed by merging the features of Molecular Imprinting technique and Screen-Printed Electrode (SPE) for the simple and fast screening of cardiac biomarker myoglobin (Myo) in point-of-care (POC). The MIP artificial receptor for Myo was prepared by electrooxidative polymerization of phenol (Ph) on a AuSPE in the presence of Myo as template molecule. The choice of the most effective protein extraction procedure from the various extraction methods tested (mildly acidic/basic solutions, pure/mixed organic solvents, solutions containing surfactants and enzymatic digestion methods), and the optimization of the thickness of the polymer film was carefully undertaken in order to improve binding characteristics of Myo to the imprinted polymer receptor and increase the sensitivity of the MIP biosensor. The film thickness was optimized by adjusting scan rate and the number of cycles during cyclic voltammetric electropolymerization of Ph. The thickness of the polyphenol nanocoating of only few nanometres (~4.4 nm), and similar to the protein diameter, brought in significant improvements in terms of sensor sensitivity. The binding affinity of MIP receptor film was estimated by fitting the experimental data to Freundlich isotherm and a ~8 fold increase in the binding affinity of Myo to the imprinted polymer (KF = 0.119 ± 0.002 ng/mL) when compared to the non-imprinted polymer (KF= 0.015 ± 0.002 ng/mL) which demonstrated excellent (re)binding affinity for the imprinted protein. |
AS Sacramento, FTC Moreira, JRL Guerreiro, APM Tavares, MGF Sales Novel biomimetic composite material for potentiometric screening of acetylcholine, a neurotransmitter in Alzheimer's disease (Journal Article) Materials Science and Engineering: C, 79 , pp. 541–549, 2017. @article{Sacramento2017, title = {Novel biomimetic composite material for potentiometric screening of acetylcholine, a neurotransmitter in Alzheimer's disease}, author = {AS Sacramento and FTC Moreira and JRL Guerreiro and APM Tavares and MGF Sales}, url = {http://www.sciencedirect.com/science/article/pii/S0928493116314771}, doi = {10.1016/j.msec.2017.05.098}, year = {2017}, date = {2017-05-15}, journal = {Materials Science and Engineering: C}, volume = {79}, pages = {541–549}, abstract = {This work describes a novel approach to produce an antibody-like biomimetic material. It includes preparing composite imprinted material never presented before, with highly conductive support nanostructures and assembling a high conductivity polymeric layer at low temperature. Overall, such highly conductive material may enhance the final features of electrically-based devices. Acetylcholine (ACh) was selected as target analyte, a neurotransmitter of importance in Alzheimer's disease. Potentiometric transduction was preferred, allowing quick responses and future adaptation to point-of-care requirements. The biomimetic material was obtained by bulk polymerization, where ACh was placed in a composite matrix of multiwalled carbon nanotubes (MWCNTs) and aniline (ANI). Subsequent polymerization, initiated by radical species, yielded a polymeric structure of polyaniline (PANI) acting as physical support of the composite. A non-imprinted material (NIM) having only PANI/MWCNT (without ACh) has been prepared for comparison of the biomimetic-imprinted material (BIM). RAMAN and Fourier Transform Infrared spectroscopy (FTIR), Transmission Electron microscopy (TEM), and Scanning Electron microscope (SEM) analysis characterized the structures of the materials. The ability of this biomaterial to rebind ACh was confirmed by including it as electroactive compound in a PVC/plasticizer mixture. The membranes with imprinted material and anionic additive presented the best analytical characteristics, with a sensitivity of 83.86 mV decade− 1 and limit of detection (LOD) of 3.45 × 10− 5 mol/L in HEPES buffer pH 4.0. Good selectivity was observed against creatinine, creatine, glucose, cysteine and urea. The electrodes were also applied on synthetic serum samples and seemed a reliable tool for screening ACh in synthetic serum samples. The overall performance showed fast response, reusability, simplicity and low price.}, keywords = {}, pubstate = {published}, tppubtype = {article} } This work describes a novel approach to produce an antibody-like biomimetic material. It includes preparing composite imprinted material never presented before, with highly conductive support nanostructures and assembling a high conductivity polymeric layer at low temperature. Overall, such highly conductive material may enhance the final features of electrically-based devices. Acetylcholine (ACh) was selected as target analyte, a neurotransmitter of importance in Alzheimer's disease. Potentiometric transduction was preferred, allowing quick responses and future adaptation to point-of-care requirements. The biomimetic material was obtained by bulk polymerization, where ACh was placed in a composite matrix of multiwalled carbon nanotubes (MWCNTs) and aniline (ANI). Subsequent polymerization, initiated by radical species, yielded a polymeric structure of polyaniline (PANI) acting as physical support of the composite. A non-imprinted material (NIM) having only PANI/MWCNT (without ACh) has been prepared for comparison of the biomimetic-imprinted material (BIM). RAMAN and Fourier Transform Infrared spectroscopy (FTIR), Transmission Electron microscopy (TEM), and Scanning Electron microscope (SEM) analysis characterized the structures of the materials. The ability of this biomaterial to rebind ACh was confirmed by including it as electroactive compound in a PVC/plasticizer mixture. The membranes with imprinted material and anionic additive presented the best analytical characteristics, with a sensitivity of 83.86 mV decade− 1 and limit of detection (LOD) of 3.45 × 10− 5 mol/L in HEPES buffer pH 4.0. Good selectivity was observed against creatinine, creatine, glucose, cysteine and urea. The electrodes were also applied on synthetic serum samples and seemed a reliable tool for screening ACh in synthetic serum samples. The overall performance showed fast response, reusability, simplicity and low price. |
NS Ferreira, APM Tavares, MHM Sá, MGF Sales New electrochemically-derived plastic antibody on a simple conductive paper support for protein detection: Application to BSA (Journal Article) Sensors and Actuators B: Chemical, 243 , pp. 1127–1136, 2017. @article{Ferreira2017, title = {New electrochemically-derived plastic antibody on a simple conductive paper support for protein detection: Application to BSA}, author = {NS Ferreira and APM Tavares and MHM Sá and MGF Sales}, url = {http://www.sciencedirect.com/science/article/pii/S0925400516320457}, doi = {10.1016/j.snb.2016.12.074}, year = {2017}, date = {2017-05-01}, journal = {Sensors and Actuators B: Chemical}, volume = {243}, pages = {1127–1136}, abstract = {A novel device for targeting proteins with a Molecularly-Imprinted Polymer (MIP) recognition material is presented herein, by employing wax paper with conductive ink as background support. Cellulose paper was modified with paraffin wax to make it waterproof, and afterwards covered by a carbon ink to make it conductive, achieving the goal to make easy and low cost supports, and, in this case, with good detection features. Bovine Serum Albumin (BSA) was used herein as target protein. Albumin has an important role in the human body and BSA is normally used as its model protein because of its good stability and low cost. The development of BSA detection systems is important in various fields, such as biochemistry, medicine and pharmacy. Raman measurements were conducted during all preparation stages of the recognition material and electrochemical assays were used to evaluate the analytical performance of the sensor. The assembly of the device was optimized by employing different polymerization timings and monomers of different chemistries and charges. In general, longer polymerization periods and the use of a positively charged monomer benefited the analytical response. The results obtained within different calibrations indicated a linear response over a wide concentration range, from 0.005 to 100 mg/mL of BSA in buffer solution. In addition, the analytical evaluation of the device under several background solutions, including synthetic and real urine, supported the good performance of the sensor and pointed out that the principle of sensor assembly may be extended to other proteins in urine. In addition, the detection capabilities of the device proposed herein are better than other BSA sensing devices relying on electrochemical transduction.}, keywords = {}, pubstate = {published}, tppubtype = {article} } A novel device for targeting proteins with a Molecularly-Imprinted Polymer (MIP) recognition material is presented herein, by employing wax paper with conductive ink as background support. Cellulose paper was modified with paraffin wax to make it waterproof, and afterwards covered by a carbon ink to make it conductive, achieving the goal to make easy and low cost supports, and, in this case, with good detection features. Bovine Serum Albumin (BSA) was used herein as target protein. Albumin has an important role in the human body and BSA is normally used as its model protein because of its good stability and low cost. The development of BSA detection systems is important in various fields, such as biochemistry, medicine and pharmacy. Raman measurements were conducted during all preparation stages of the recognition material and electrochemical assays were used to evaluate the analytical performance of the sensor. The assembly of the device was optimized by employing different polymerization timings and monomers of different chemistries and charges. In general, longer polymerization periods and the use of a positively charged monomer benefited the analytical response. The results obtained within different calibrations indicated a linear response over a wide concentration range, from 0.005 to 100 mg/mL of BSA in buffer solution. In addition, the analytical evaluation of the device under several background solutions, including synthetic and real urine, supported the good performance of the sensor and pointed out that the principle of sensor assembly may be extended to other proteins in urine. In addition, the detection capabilities of the device proposed herein are better than other BSA sensing devices relying on electrochemical transduction. |
JRL Guerreiro, N Teixeira, VAP Freitas, MGF Sales, DS Sutherland A saliva molecular imprinted localized surface plasmon resonance biosensor for wine astringency estimation (Journal Article) Food Chemistry, 233 , pp. 457–466, 2017. @article{Guerreiro2017, title = {A saliva molecular imprinted localized surface plasmon resonance biosensor for wine astringency estimation}, author = {JRL Guerreiro and N Teixeira and VAP Freitas and MGF Sales and DS Sutherland}, url = {http://www.sciencedirect.com/science/article/pii/S0308814617306246}, doi = {10.1016/j.foodchem.2017.04.051}, year = {2017}, date = {2017-04-12}, journal = {Food Chemistry}, volume = {233}, pages = {457–466}, abstract = {Wine astringency was evaluated based on the interaction of two complex matrices (red wine and saliva) by combining localized surface plasmon resonance (LSPR) and molecular imprinted polymers (MIP) at gold nanodisks as an alternative to sensorial analysis. The main objective of the work was to simulate wine astringency inside the mouth by mimicking this biological system. The LSPR/MIP sensor provided a linear response for astringency expressed in pentagalloyl glucose (PGG) units in concentrations ranging from 1 to 140 μmol/L. The sensor was also applied to wine samples correlating well with sensorial analysis obtained by a trained panel. The correlation of astringency and wine composition was also evaluated showing that anthocyanins may have an important role, not only for pigmentation but also in astringency.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Wine astringency was evaluated based on the interaction of two complex matrices (red wine and saliva) by combining localized surface plasmon resonance (LSPR) and molecular imprinted polymers (MIP) at gold nanodisks as an alternative to sensorial analysis. The main objective of the work was to simulate wine astringency inside the mouth by mimicking this biological system. The LSPR/MIP sensor provided a linear response for astringency expressed in pentagalloyl glucose (PGG) units in concentrations ranging from 1 to 140 μmol/L. The sensor was also applied to wine samples correlating well with sensorial analysis obtained by a trained panel. The correlation of astringency and wine composition was also evaluated showing that anthocyanins may have an important role, not only for pigmentation but also in astringency. |
FTC Moreira, MGF Sales Smart naturally plastic antibody based on poly(α-cyclodextrin) polymer for β-amyloid-42 soluble oligomer detection (Journal Article) Sensors and Actuators B: Chemical, 240 , pp. 229–238, 2017. @article{Moreira2017b, title = {Smart naturally plastic antibody based on poly(α-cyclodextrin) polymer for β-amyloid-42 soluble oligomer detection}, author = {FTC Moreira and MGF Sales}, url = {http://www.sciencedirect.com/science/article/pii/S0925400516313831}, doi = {10.1016/j.snb.2016.08.150}, year = {2017}, date = {2017-03-01}, journal = {Sensors and Actuators B: Chemical}, volume = {240}, pages = {229–238}, abstract = {This work introduces new developments into the conventional protocol of protein imprinting. It uses as principle that when the polymeric matrix is made from native building blocks in nature (amino acids, sugars, lipids or nucleic acids), conformational changes of the template protein during the polymer synthesis may be avoided or limited. Thus, the polymeric film around the protein is build-up with biomolecules that co-exist with the protein in nature. This approach is named herein as BIOPLAST, in an analogy to a Plastic material made from biological building blocks. This concept was tested herein by employing a sugar monomer (α-Cyclodextrin, α-Cd) to target a peptide biomarker (β-Amyloid-42, Aβ-42) that is relevant in Alzheimer disease. The BIOPLAST-based biosensor consisted of a screen-printed electrode (SPE) having an Au-working electrode area coated with a polyaniline (PANI) film and subsequently modified by the plastic antibody (MCd/PANI/Au-SPE). The plastic antibody was assembled by electropolymerizing αCd in the presence of Aβ-42 and the peptide molecules entrapped in the polymer film were removed by acidic action. Analysis by Atomic Force Microscopy, and Fourier Transformed Infrared and Raman spectroscopies confirmed the surface modification. The ability of the BIOPLAST film to rebind Aβ-42 was followed by electrochemical impedance spectroscopy (EIS) and square wave voltammetry (SWV), and compared to a control film without plastic antibody (NCd/PANI/Au-SPE). The MCd/PANI/Au-SPE devices displayed linear responses and limit of detection to Aβ-42 in EIS and SWV assays, down to 0.25 ng/mL and 0.20 ng/mL respectively. The dissociation constant between the BIOPLAST and Aβ-42 were 0.2 ± 0.5 ng/mL (1.8 ± 0.5 for the control material). MCd/PANI/Au-SPE materials assembled on screen-printed electrodes showed great promising features, regarding its possible application in point-of-care.}, keywords = {}, pubstate = {published}, tppubtype = {article} } This work introduces new developments into the conventional protocol of protein imprinting. It uses as principle that when the polymeric matrix is made from native building blocks in nature (amino acids, sugars, lipids or nucleic acids), conformational changes of the template protein during the polymer synthesis may be avoided or limited. Thus, the polymeric film around the protein is build-up with biomolecules that co-exist with the protein in nature. This approach is named herein as BIOPLAST, in an analogy to a Plastic material made from biological building blocks. This concept was tested herein by employing a sugar monomer (α-Cyclodextrin, α-Cd) to target a peptide biomarker (β-Amyloid-42, Aβ-42) that is relevant in Alzheimer disease. The BIOPLAST-based biosensor consisted of a screen-printed electrode (SPE) having an Au-working electrode area coated with a polyaniline (PANI) film and subsequently modified by the plastic antibody (MCd/PANI/Au-SPE). The plastic antibody was assembled by electropolymerizing αCd in the presence of Aβ-42 and the peptide molecules entrapped in the polymer film were removed by acidic action. Analysis by Atomic Force Microscopy, and Fourier Transformed Infrared and Raman spectroscopies confirmed the surface modification. The ability of the BIOPLAST film to rebind Aβ-42 was followed by electrochemical impedance spectroscopy (EIS) and square wave voltammetry (SWV), and compared to a control film without plastic antibody (NCd/PANI/Au-SPE). The MCd/PANI/Au-SPE devices displayed linear responses and limit of detection to Aβ-42 in EIS and SWV assays, down to 0.25 ng/mL and 0.20 ng/mL respectively. The dissociation constant between the BIOPLAST and Aβ-42 were 0.2 ± 0.5 ng/mL (1.8 ± 0.5 for the control material). MCd/PANI/Au-SPE materials assembled on screen-printed electrodes showed great promising features, regarding its possible application in point-of-care. |
FTC Moreira, MGF Sales, MD Lorenzo Towards timely Alzheimer diagnosis: A self-powered amperometric biosensor for the neurotransmitter acetylcholine (Journal Article) Biosensors and Bioelectronics, 87 , pp. 607–614, 2017. @article{Moreira2017, title = {Towards timely Alzheimer diagnosis: A self-powered amperometric biosensor for the neurotransmitter acetylcholine}, author = {FTC Moreira and MGF Sales and MD Lorenzo}, url = {http://www.sciencedirect.com/science/article/pii/S0956566316308582}, doi = {10.1016/j.bios.2016.08.104}, year = {2017}, date = {2017-01-15}, journal = {Biosensors and Bioelectronics}, volume = {87}, pages = {607–614}, abstract = {Serious brain disorders, such as the Alzheimer's Disease (AD), are associated with a marked drop in the levels of important neurotransmitters, such as acetylcholine (ACh). Real time monitoring of such biomarkers can therefore play a critical role in enhancing AD therapies by allowing timely diagnosis, verifications of treatment effectiveness, and developments of new medicines. In this study, we present the first acetylcholine/oxygen hybrid enzymatic fuel cell for the self-powered on site detection of ACh in plasma, which is based on the combination of an enzymatic anode with a Pt cathode. Firstly, an effective acetylcholinesterase immobilized electrode was developed and its electrochemical performance evaluated. Highly porous gold was used as the electrode material, and the enzyme was immobilized via a one step rapid and simple procedure that does not require the use of harsh chemicals or any electrode/enzyme pre-treatments. The resulting enzymatic electrode was subsequently used as the anode of a miniature flow-through membrane-less fuel cell and showed excellent response to varying concentrations of ACh. The peak power generated by the fuel cell was 4 nW at a voltage of 260 mV and with a current density of 9 μA cm−2. The limit of detection of the fuel cell sensor was 10 μM, with an average response time as short as 3 min. These exciting results open new horizons for point-of-care Alzheimer diagnosis and provide an attractive potential alternative to established methods that require laborious and time-consuming sample treatments and expensive instruments.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Serious brain disorders, such as the Alzheimer's Disease (AD), are associated with a marked drop in the levels of important neurotransmitters, such as acetylcholine (ACh). Real time monitoring of such biomarkers can therefore play a critical role in enhancing AD therapies by allowing timely diagnosis, verifications of treatment effectiveness, and developments of new medicines. In this study, we present the first acetylcholine/oxygen hybrid enzymatic fuel cell for the self-powered on site detection of ACh in plasma, which is based on the combination of an enzymatic anode with a Pt cathode. Firstly, an effective acetylcholinesterase immobilized electrode was developed and its electrochemical performance evaluated. Highly porous gold was used as the electrode material, and the enzyme was immobilized via a one step rapid and simple procedure that does not require the use of harsh chemicals or any electrode/enzyme pre-treatments. The resulting enzymatic electrode was subsequently used as the anode of a miniature flow-through membrane-less fuel cell and showed excellent response to varying concentrations of ACh. The peak power generated by the fuel cell was 4 nW at a voltage of 260 mV and with a current density of 9 μA cm−2. The limit of detection of the fuel cell sensor was 10 μM, with an average response time as short as 3 min. These exciting results open new horizons for point-of-care Alzheimer diagnosis and provide an attractive potential alternative to established methods that require laborious and time-consuming sample treatments and expensive instruments. |
AR Cardoso, G Cabral-Miranda, A Reyes-Sandoval, MF Bachmann, MGF Sales Detecting circulating antibodies by controlled surface modification with specific target proteins: Application to malaria (Journal Article) Biosensors and Bioelectronics, 91 , pp. 833–841, 2017. @article{Cardoso2017, title = {Detecting circulating antibodies by controlled surface modification with specific target proteins: Application to malaria}, author = {AR Cardoso and G Cabral-Miranda and A Reyes-Sandoval and MF Bachmann and MGF Sales}, url = {http://www.sciencedirect.com/science/article/pii/S0956566317300313}, doi = {10.1016/j.bios.2017.01.031}, year = {2017}, date = {2017-01-15}, journal = {Biosensors and Bioelectronics}, volume = {91}, pages = {833–841}, abstract = {Sensitive detection of specific antibodies by biosensors has become of major importance for monitoring and controlling epidemics. Here we report a development of a biosensor able to specifically measure antibodies in a drop of unmodified blood serum. Within minutes, the detection system measures presence of antibodies against Plasmodium vivax, a causing agent for malaria. The biosensor consists of a layer of carbon nanotubes (CNTs) which were casted on a carbon working electrode area of a three-electrode system and oxidized. An amine layer was produced next by modifying the surface with EDAC/NHS followed by reaction with a diamine compound. Finally, the protein fragments derived from P. vivax containing well-known antigen sequences were casted on this layer and bound through electrostatic interactions, involving hydrogen and ionic bonding. All these chemical changes occurring at the carbon surface along the biosensor assembly were followed and confirmed by Fourier Transformed Infrared s pectrometry (FTIR) and Raman spectroscopy. The presence of antibodies in serum was detected by monitoring the electrical properties of the layer, making use of cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and square wave voltammetry (SWV), against a standard iron probe. Overall, the charge-transfer resistance decreased after antibody binding, because there was an additional amount of protein bound to the surface. This hindered the access of the iron redox probe to the conductive support at the electrode surface. Electrical changes could be measured at antibody concentration as low as ~6–50 pg/L (concentrations in the range of 10–15 M) and as high as ~70 μg/L. Specific measurement with low background was even possible in undiluted serum. Hence, this novel biosensor allows assessing serum antibody levels in real time and in un-manipulated serum samples on-site where needed}, keywords = {}, pubstate = {published}, tppubtype = {article} } Sensitive detection of specific antibodies by biosensors has become of major importance for monitoring and controlling epidemics. Here we report a development of a biosensor able to specifically measure antibodies in a drop of unmodified blood serum. Within minutes, the detection system measures presence of antibodies against Plasmodium vivax, a causing agent for malaria. The biosensor consists of a layer of carbon nanotubes (CNTs) which were casted on a carbon working electrode area of a three-electrode system and oxidized. An amine layer was produced next by modifying the surface with EDAC/NHS followed by reaction with a diamine compound. Finally, the protein fragments derived from P. vivax containing well-known antigen sequences were casted on this layer and bound through electrostatic interactions, involving hydrogen and ionic bonding. All these chemical changes occurring at the carbon surface along the biosensor assembly were followed and confirmed by Fourier Transformed Infrared s pectrometry (FTIR) and Raman spectroscopy. The presence of antibodies in serum was detected by monitoring the electrical properties of the layer, making use of cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and square wave voltammetry (SWV), against a standard iron probe. Overall, the charge-transfer resistance decreased after antibody binding, because there was an additional amount of protein bound to the surface. This hindered the access of the iron redox probe to the conductive support at the electrode surface. Electrical changes could be measured at antibody concentration as low as ~6–50 pg/L (concentrations in the range of 10–15 M) and as high as ~70 μg/L. Specific measurement with low background was even possible in undiluted serum. Hence, this novel biosensor allows assessing serum antibody levels in real time and in un-manipulated serum samples on-site where needed |
AR Khan, AR Cardoso, MGF Sales, S Merino, JM Tomás, FX Rius, J Riu Artificial receptors for the electrochemical detection of bacterial flagellar filaments from Proteus mirabilis (Journal Article) Sensors and Actuators B: Chemical, 244 , pp. 732–741, 2017. @article{Khan2017, title = {Artificial receptors for the electrochemical detection of bacterial flagellar filaments from Proteus mirabilis}, author = {AR Khan and AR Cardoso and MGF Sales and S Merino and JM Tomás and FX Rius and J Riu}, url = {http://www.sciencedirect.com/science/article/pii/S0925400517300187}, doi = {10.1016/j.snb.2017.01.018}, year = {2017}, date = {2017-01-04}, journal = {Sensors and Actuators B: Chemical}, volume = {244}, pages = {732–741}, abstract = {In this paper for the first time we successfully detect bacterial flagellar filaments from Proteus mirabilis using molecularly imprinted artificial receptors. These receptors acted as a sensing layer of the biosensors, assembled by imprinting flagellar proteins onto a polymeric backbone of electropolymerized phenol. In short, flagellar filaments were absorbed onto a carbon support, phenol was electropolymerized around it through the carbon conductive matrix to create the protein molecular molds, and finally the flagellar proteins were removed by enzymatic and electrochemical action. Each removed flagellar protein gave rise to an imprinted site with eventual rebinding ability. Electrical impedance spectroscopy (EIS) and square wave voltammetry (SWV) were employed to measure the interaction of flagellar filaments with the sensing layer assembled on commercial screen-printed electrodes, providing low detection limits, high precision and selectivity toward the targeted protein. The detection limit was 0.7 ng/mL by EIS and 0.9 ng/mL by SWV. The artificial receptors were further assembled on home-made paper-printed electrodes, with the three-electrode system printed on a paper substrate, offering the possibility of detecting flagellar filaments at as low as 0.6 ng/mL with a disposable and cost-effective portable device. To the best of our knowledge this is the first sensing device where molecularly imprinted artificial receptors are tailored on home-made electrode based on paper substrates with three electrodes assembled together, which is a suitable approach for the fabrication of easy and cost-effective tailored electrodes.}, keywords = {}, pubstate = {published}, tppubtype = {article} } In this paper for the first time we successfully detect bacterial flagellar filaments from Proteus mirabilis using molecularly imprinted artificial receptors. These receptors acted as a sensing layer of the biosensors, assembled by imprinting flagellar proteins onto a polymeric backbone of electropolymerized phenol. In short, flagellar filaments were absorbed onto a carbon support, phenol was electropolymerized around it through the carbon conductive matrix to create the protein molecular molds, and finally the flagellar proteins were removed by enzymatic and electrochemical action. Each removed flagellar protein gave rise to an imprinted site with eventual rebinding ability. Electrical impedance spectroscopy (EIS) and square wave voltammetry (SWV) were employed to measure the interaction of flagellar filaments with the sensing layer assembled on commercial screen-printed electrodes, providing low detection limits, high precision and selectivity toward the targeted protein. The detection limit was 0.7 ng/mL by EIS and 0.9 ng/mL by SWV. The artificial receptors were further assembled on home-made paper-printed electrodes, with the three-electrode system printed on a paper substrate, offering the possibility of detecting flagellar filaments at as low as 0.6 ng/mL with a disposable and cost-effective portable device. To the best of our knowledge this is the first sensing device where molecularly imprinted artificial receptors are tailored on home-made electrode based on paper substrates with three electrodes assembled together, which is a suitable approach for the fabrication of easy and cost-effective tailored electrodes. |
2016
GV Martins, AC Marques, E Fortunato, MGF Sales 8-hydroxy-2'-deoxyguanosine (8-OHdG) biomarker detection down to picoMolar level on a plastic antibody film (Journal Article) Biosensors and Bioelectronics, 86 , pp. 225-234, 2016. @article{Martins2016b, title = {8-hydroxy-2'-deoxyguanosine (8-OHdG) biomarker detection down to picoMolar level on a plastic antibody film}, author = {GV Martins and AC Marques and E Fortunato and MGF Sales }, url = {http://dx.doi.org/10.1016/j.bios.2016.06.052}, doi = {10.1016/j.bios.2016.06.052}, year = {2016}, date = {2016-12-15}, journal = {Biosensors and Bioelectronics}, volume = {86}, pages = {225-234}, abstract = {An innovative biosensor assembly relying on a simple and straightforward in-situ construction is presented to monitor urinary 8-hydroxy-2′-deoxyguanosine (8-OHdG) down to the pmol/L level. The sensing film of the biosensor consisted of a molecularly imprinted polymer (MIP) layer for 8-OHdG assembled on a gold electrode through electropolymerization of monomer combined with the template. The analytical features of the resulting biosensor were assessed by Cyclic Voltammetry (CV) and Electrochemical Impedance Spectroscopy (EIS). Some experimental parameters such as the initial concentration of the monomer and the ratio template-monomer were investigated and optimized in order to finely tune the performance of the MIP-based sensor. Under optimal conditions, the developed biosensor was able to rebind 8-OHdG with a linear response against EIS from 0.1 to 100 pg/ml 3.5-3500 pM. The interference of coexisting species was tested, also with calibrations on urine samples, and good selectivity towards 8-OHdG was obtained. RAMAN spectroscopy, FTIR and SEM evaluations of the prepared films confirmed the formation of a polyphenol thin-film on the electrode surface. The presence and distribution of the imprinted cavities on the MIP layer was confirmed by confocal microscopy imaging of the film, after a post-treatment with Fluorescein Isothiocyanate (FITC) labeled 8-OHdG antibody. Overall, this label-free biosensor for urinary 8-OHdG detection constitutes a promising low-cost alternative to the conventional immunoassay approaches, due to its simplicity, stability, high sensitivity and selectivity for biological sample assays, opening new doors for other applications.}, keywords = {}, pubstate = {published}, tppubtype = {article} } An innovative biosensor assembly relying on a simple and straightforward in-situ construction is presented to monitor urinary 8-hydroxy-2′-deoxyguanosine (8-OHdG) down to the pmol/L level. The sensing film of the biosensor consisted of a molecularly imprinted polymer (MIP) layer for 8-OHdG assembled on a gold electrode through electropolymerization of monomer combined with the template. The analytical features of the resulting biosensor were assessed by Cyclic Voltammetry (CV) and Electrochemical Impedance Spectroscopy (EIS). Some experimental parameters such as the initial concentration of the monomer and the ratio template-monomer were investigated and optimized in order to finely tune the performance of the MIP-based sensor. Under optimal conditions, the developed biosensor was able to rebind 8-OHdG with a linear response against EIS from 0.1 to 100 pg/ml 3.5-3500 pM. The interference of coexisting species was tested, also with calibrations on urine samples, and good selectivity towards 8-OHdG was obtained. RAMAN spectroscopy, FTIR and SEM evaluations of the prepared films confirmed the formation of a polyphenol thin-film on the electrode surface. The presence and distribution of the imprinted cavities on the MIP layer was confirmed by confocal microscopy imaging of the film, after a post-treatment with Fluorescein Isothiocyanate (FITC) labeled 8-OHdG antibody. Overall, this label-free biosensor for urinary 8-OHdG detection constitutes a promising low-cost alternative to the conventional immunoassay approaches, due to its simplicity, stability, high sensitivity and selectivity for biological sample assays, opening new doors for other applications. |
LAANA Truta, AL Castro, S Tarelho, P Costa, MGF Sales, HM Teixeira Antidepressants detection and quantification in whole blood samples by GC–MS/MS, for forensic purposes (Journal Article) Journal of Pharmaceutical and Biomedical Analysis, 128 , pp. 496-503, 2016. @article{Truta2016b, title = {Antidepressants detection and quantification in whole blood samples by GC–MS/MS, for forensic purposes}, author = {LAANA Truta and AL Castro and S Tarelho and P Costa and MGF Sales and HM Teixeira}, url = {http://www.sciencedirect.com/science/journal/07317085/128}, doi = {10.1016/j.jpba.2016.06.027}, year = {2016}, date = {2016-09-05}, journal = {Journal of Pharmaceutical and Biomedical Analysis}, volume = {128}, pages = {496-503}, abstract = {Depression is among the most prevalent psychiatric disorders of our society, leading to an increase in antidepressant drug consumption that needs to be accurately determined in whole blood samples in Forensic Toxicology Laboratories. For this purpose, this work presents a new gas chromatography tandem mass spectrometry (GC–MS/MS) method targeting the simultaneous and rapid determination of 14 common Antidepressants in whole blood: 13 Antidepressants (amitriptyline, citalopram, clomipramine, dothiepin, fluoxetine, imipramine, mianserin, mirtazapine, nortryptiline, paroxetine, sertraline, trimipramine and venlafaxine) and 1 Metabolite (N-desmethylclomipramine). Solid-phase extraction was used prior to chromatographic separation. Chromatographic and MS/MS parameters were selected to improve sensitivity, peak resolution and unequivocal identification of the eluted analyte. The detection was performed on a triple quadrupole tandem MS in selected ion monitoring (SIM) mode in tandem, using electronic impact ionization. Clomipramine-D3 and trimipramine-D3 were used as deutered internal standards. The validation parameters included linearity, limits of detection, lower limit of quantification, selectivity/specificity, extraction efficiency, carry-over, precision and robustness, and followed internationally accepted guidelines. Limits of quantification and detection were lower than therapeutic and sub-therapeutic concentration ranges. Overall, the method offered good selectivity, robustness and quick response (<16 min) for typical concentration ranges, both for therapeutic and lethal levels.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Depression is among the most prevalent psychiatric disorders of our society, leading to an increase in antidepressant drug consumption that needs to be accurately determined in whole blood samples in Forensic Toxicology Laboratories. For this purpose, this work presents a new gas chromatography tandem mass spectrometry (GC–MS/MS) method targeting the simultaneous and rapid determination of 14 common Antidepressants in whole blood: 13 Antidepressants (amitriptyline, citalopram, clomipramine, dothiepin, fluoxetine, imipramine, mianserin, mirtazapine, nortryptiline, paroxetine, sertraline, trimipramine and venlafaxine) and 1 Metabolite (N-desmethylclomipramine). Solid-phase extraction was used prior to chromatographic separation. Chromatographic and MS/MS parameters were selected to improve sensitivity, peak resolution and unequivocal identification of the eluted analyte. The detection was performed on a triple quadrupole tandem MS in selected ion monitoring (SIM) mode in tandem, using electronic impact ionization. Clomipramine-D3 and trimipramine-D3 were used as deutered internal standards. The validation parameters included linearity, limits of detection, lower limit of quantification, selectivity/specificity, extraction efficiency, carry-over, precision and robustness, and followed internationally accepted guidelines. Limits of quantification and detection were lower than therapeutic and sub-therapeutic concentration ranges. Overall, the method offered good selectivity, robustness and quick response (<16 min) for typical concentration ranges, both for therapeutic and lethal levels. |
AR Cardoso, FTC Moreira, R Fernandes, MGF Sales Novel and simple electrochemical biosensor monitoring attomolar levels of miRNA-155 in breast cancer (Journal Article) Biosensors and Bioelectronics, 80 , pp. 621-630, 2016. @article{Cardoso2016b, title = {Novel and simple electrochemical biosensor monitoring attomolar levels of miRNA-155 in breast cancer}, author = {AR Cardoso and FTC Moreira and R Fernandes and MGF Sales }, url = {http://www.sciencedirect.com/science/article/pii/S0956566316301427}, doi = {10.1016/j.bios.2016.02.035}, year = {2016}, date = {2016-06-15}, journal = {Biosensors and Bioelectronics}, volume = {80}, pages = {621-630}, abstract = {This work, describes for the first time, a simple biosensing design to yield an ultrasensitive electrochemical biosensor for a cancer biomarker detection, miRNA-155, with linear response down to the attomolar range. MiRNA-155 was selected for being overexpressed in breast cancer. The biosensor was assembled in two stages: (1) the immobilization of the anti-miRNA-155 that was thiol modified on an Au-screen printed electrode (Au-SPE), followed by (2) blocking the areas of non-specific binding with mercaptosuccinic acid. Atomic force microscopy (AFM) and electrochemical techniques including cyclic voltammetry (CV), impedance spectroscopy (EIS) and square wave voltammetry (SWV) confirmed the surface modification of these devices and their ability to hybridize successfully and stably with miRNA-155. The final biosensor provided a sensitive detection of miRNA-155 from 10 aM to 1.0 nM with a low detection limit (LOD) of 5.7 aM in real human serum samples. Good results were obtained in terms of selectivity towards breast cancer antigen CA-15.3 and bovine serum albumin (BSA). Raw fluid extracts from cell-lines of melanoma did not affect the biosensor response (no significant change of the blank), while raw extracts from breast cancer yielded a positive signal against miRNA-155. This simple and sensitive strategy is a promising alternative for simultaneous quantitative analysis of multiple miRNA in physiological fluids for biomedical research and point-of-care (POC) diagnosis.}, keywords = {}, pubstate = {published}, tppubtype = {article} } This work, describes for the first time, a simple biosensing design to yield an ultrasensitive electrochemical biosensor for a cancer biomarker detection, miRNA-155, with linear response down to the attomolar range. MiRNA-155 was selected for being overexpressed in breast cancer. The biosensor was assembled in two stages: (1) the immobilization of the anti-miRNA-155 that was thiol modified on an Au-screen printed electrode (Au-SPE), followed by (2) blocking the areas of non-specific binding with mercaptosuccinic acid. Atomic force microscopy (AFM) and electrochemical techniques including cyclic voltammetry (CV), impedance spectroscopy (EIS) and square wave voltammetry (SWV) confirmed the surface modification of these devices and their ability to hybridize successfully and stably with miRNA-155. The final biosensor provided a sensitive detection of miRNA-155 from 10 aM to 1.0 nM with a low detection limit (LOD) of 5.7 aM in real human serum samples. Good results were obtained in terms of selectivity towards breast cancer antigen CA-15.3 and bovine serum albumin (BSA). Raw fluid extracts from cell-lines of melanoma did not affect the biosensor response (no significant change of the blank), while raw extracts from breast cancer yielded a positive signal against miRNA-155. This simple and sensitive strategy is a promising alternative for simultaneous quantitative analysis of multiple miRNA in physiological fluids for biomedical research and point-of-care (POC) diagnosis. |
TSCR Rebelo, CM Pereira, MGF Sales, JPC Noronha, F Silva Protein imprinted material electrochemical sensor for determination of Annexin A3 in biological samples (Journal Article) Electrochimica Acta, 190 , pp. 887–893, 2016. @article{Rebelo2016b, title = {Protein imprinted material electrochemical sensor for determination of Annexin A3 in biological samples}, author = {TSCR Rebelo and CM Pereira and MGF Sales and JPC Noronha and F Silva}, url = {http://www.sciencedirect.com/science/article/pii/S0013468615311397}, doi = {10.1016/j.electacta.2015.12.214}, year = {2016}, date = {2016-06-01}, journal = {Electrochimica Acta}, volume = {190}, pages = {887–893}, abstract = {The development of fast and reliable methods for protein determination are of great relevance to a diversity of areas from industry to diagnostics. Molecular Imprinted Materials (MIM) has proved to be an interesting methodology for protein analysis however further studies of the effect of the experimental parameters and starting materials in the performance of the MIM are still required. Caffeic acid (CAF) is employed for the first time as a monomer to tailor a synthetic receptor for a protein target. This was done by bulk-electropolymerization, applying a constant potential of +2.0 V, for 30 s, on a carbon screen-printed electrode, immersed in a solution of protein and CAF prepared in phosphate buffer. Annexin A3 (ANXA3) was selected as protein target due to the fact that this is an emerging biomarker in prostate cancer. The assembly of the protein imprinted material (PIM) was followed by Electrochemical Impedance Spectroscopy (EIS) and Raman Spectroscopy. A non-imprinted material (NIM) was prepared in parallel as control. Square wave voltammetry (SWV) was used to monitor the electrochemical signal of the [Fe(CN)6]3−/[Fe(CN)6]4− redox for the quantification of ANXA3. The optimized PIM-based device showed average detection limits (LOD) of 0.095 ng/mL, a linear behavior against log (concentration) between 0.10, and 200 ng/mL and good selectivity. The NIM-based device showed random behavior against protein concentration. Finally, the PIM-sensor was successfully applied to the analysis of ANXA3 in spiked urine samples.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The development of fast and reliable methods for protein determination are of great relevance to a diversity of areas from industry to diagnostics. Molecular Imprinted Materials (MIM) has proved to be an interesting methodology for protein analysis however further studies of the effect of the experimental parameters and starting materials in the performance of the MIM are still required. Caffeic acid (CAF) is employed for the first time as a monomer to tailor a synthetic receptor for a protein target. This was done by bulk-electropolymerization, applying a constant potential of +2.0 V, for 30 s, on a carbon screen-printed electrode, immersed in a solution of protein and CAF prepared in phosphate buffer. Annexin A3 (ANXA3) was selected as protein target due to the fact that this is an emerging biomarker in prostate cancer. The assembly of the protein imprinted material (PIM) was followed by Electrochemical Impedance Spectroscopy (EIS) and Raman Spectroscopy. A non-imprinted material (NIM) was prepared in parallel as control. Square wave voltammetry (SWV) was used to monitor the electrochemical signal of the [Fe(CN)6]3−/[Fe(CN)6]4− redox for the quantification of ANXA3. The optimized PIM-based device showed average detection limits (LOD) of 0.095 ng/mL, a linear behavior against log (concentration) between 0.10, and 200 ng/mL and good selectivity. The NIM-based device showed random behavior against protein concentration. Finally, the PIM-sensor was successfully applied to the analysis of ANXA3 in spiked urine samples. |
APM Tavares, NS Ferreira, LAANA Truta, MGF Sales Conductive paper with antibody like film for electrical readings of biomolecules (Journal Article) Scientific reports, 6 , 2016. @article{Tavares2016, title = {Conductive paper with antibody like film for electrical readings of biomolecules}, author = {APM Tavares and NS Ferreira and LAANA Truta and MGF Sales }, url = {http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4876510/}, doi = { 10.1038/srep26132}, year = {2016}, date = {2016-05-23}, journal = {Scientific reports}, volume = {6}, abstract = {This work reports a novel way of producing an inexpensive substrate support to assemble a sensing film, designed for the electrical transduction of an intended biomolecule. The support uses cellulose paper as substrate, made hydrophobic with solid wax and covered by a home-made conductive ink having graphite as core material. The hydrophobicity of the paper was confirmed by contact angle measurements and the conductive ink composition was optimized with regard to its adhesion, conductivity, and thermal stability. This support was further modified targeting its application in quantitative analysis. Carnitine (CRT) was selected as target compound, a cancer biomarker. The recognition material consisted of an antibody-like receptor film for CRT, tailored on the support and prepared by electrically-sustained polymerization of 3,4-ethylenedioxythiophene (EDOT) or dodecylbenzenesulfonic acid (DBS). Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy analysis confirmed the presence of the polymeric film on the support, and the performance of the devices was extensively evaluated with regard to linear response ranges, selectivity, applicability, and reusability. Overall, the paper-based sensors offer simplicity of fabrication, low cost and excellent reusability features. The design could also be extended to other applications in electricalbased approaches to be used in point-of-care (POC).}, keywords = {}, pubstate = {published}, tppubtype = {article} } This work reports a novel way of producing an inexpensive substrate support to assemble a sensing film, designed for the electrical transduction of an intended biomolecule. The support uses cellulose paper as substrate, made hydrophobic with solid wax and covered by a home-made conductive ink having graphite as core material. The hydrophobicity of the paper was confirmed by contact angle measurements and the conductive ink composition was optimized with regard to its adhesion, conductivity, and thermal stability. This support was further modified targeting its application in quantitative analysis. Carnitine (CRT) was selected as target compound, a cancer biomarker. The recognition material consisted of an antibody-like receptor film for CRT, tailored on the support and prepared by electrically-sustained polymerization of 3,4-ethylenedioxythiophene (EDOT) or dodecylbenzenesulfonic acid (DBS). Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy analysis confirmed the presence of the polymeric film on the support, and the performance of the devices was extensively evaluated with regard to linear response ranges, selectivity, applicability, and reusability. Overall, the paper-based sensors offer simplicity of fabrication, low cost and excellent reusability features. The design could also be extended to other applications in electricalbased approaches to be used in point-of-care (POC). |
AR Khan, FTC Moreira, J Riu, MGF Sales Plastic antibody for the electrochemical detection of bacterial surface proteins (Journal Article) Sensors and Actuators B: Chemical, 233 , pp. 697-704, 2016. @article{Khan2016, title = {Plastic antibody for the electrochemical detection of bacterial surface proteins}, author = {AR Khan and FTC Moreira and J Riu and MGF Sales }, url = {http://www.sciencedirect.com/science/article/pii/S0925400516305573 }, doi = {10.1016/j.snb.2016.04.075}, year = {2016}, date = {2016-05-10}, journal = {Sensors and Actuators B: Chemical}, volume = {233}, pages = {697-704}, abstract = {This work presents a novel molecularly imprinted polymer (MIP) for the indirect detection of bacteria, by targeting an outer membrane protein on a disposable device. Protein A (PA) was selected for this purpose, as a representative protein of the outer surface of Staphylococcus aureus. The imprinted polymer was assembled directly on a film of single walled carbon nanotubes (SWCNTs), placed on screen-printed electrodes (SPEs). The MIP material was produced by electropolymerizing 3-aminophenol in the presence of the protein template (PA) using cyclic voltammetry (CV). The proteins entrapped at the polymeric backbone were digested by the action of proteolytic activity of proteinase K and then washed away to create vacant sites. The performance of the corresponding imprinted and non-imprinted electrodes was evaluated by EIS and the effect of several variables, such as monomer and template concentrations, or thickness of imprinting surface, was controlled and optimized by the number of CV cycles. The detection limit of the MIP-based sensors was 0.60 nM in MES buffer. High repeatability and good selectivity were observed in the presence of a model protein BSA. The sensor performance was also tested to check the effect of inorganic ions in tap water. The detection limit observed was 16.83 nM, with a recovery factor of 91.1 ± 6.6%. The sensor described in this work is a potential tool for screening PA on-site, due to the simplicity of fabrication, disposability, short response time, low cost, good sensitivity and selectivity.}, keywords = {}, pubstate = {published}, tppubtype = {article} } This work presents a novel molecularly imprinted polymer (MIP) for the indirect detection of bacteria, by targeting an outer membrane protein on a disposable device. Protein A (PA) was selected for this purpose, as a representative protein of the outer surface of Staphylococcus aureus. The imprinted polymer was assembled directly on a film of single walled carbon nanotubes (SWCNTs), placed on screen-printed electrodes (SPEs). The MIP material was produced by electropolymerizing 3-aminophenol in the presence of the protein template (PA) using cyclic voltammetry (CV). The proteins entrapped at the polymeric backbone were digested by the action of proteolytic activity of proteinase K and then washed away to create vacant sites. The performance of the corresponding imprinted and non-imprinted electrodes was evaluated by EIS and the effect of several variables, such as monomer and template concentrations, or thickness of imprinting surface, was controlled and optimized by the number of CV cycles. The detection limit of the MIP-based sensors was 0.60 nM in MES buffer. High repeatability and good selectivity were observed in the presence of a model protein BSA. The sensor performance was also tested to check the effect of inorganic ions in tap water. The detection limit observed was 16.83 nM, with a recovery factor of 91.1 ± 6.6%. The sensor described in this work is a potential tool for screening PA on-site, due to the simplicity of fabrication, disposability, short response time, low cost, good sensitivity and selectivity. |
BVM Silva, BAG Rodríguez, MGF Sales, MDP Sotomayor, RAF Dutra An ultrasensitive human cardiac troponin T graphene screen-printed electrode based on electropolymerized-molecularly imprinted conducting polymer (Journal Article) Biosensors and Bioelectronics, 77 , pp. 978–985, 2016. @article{Silva2016, title = {An ultrasensitive human cardiac troponin T graphene screen-printed electrode based on electropolymerized-molecularly imprinted conducting polymer}, author = {BVM Silva and BAG Rodríguez and MGF Sales and MDP Sotomayor and RAF Dutra}, url = {http://www.sciencedirect.com/science/article/pii/S0956566315305261}, doi = {10.1016/j.bios.2015.10.068}, year = {2016}, date = {2016-03-15}, journal = {Biosensors and Bioelectronics}, volume = {77}, pages = {978–985}, abstract = {A nano-molecularly imprinted polymer (N-MIP) assembled on a screen-printed electrode for the cardiac troponin T (cTnT) was developed. The biomimetic surface was obtained by a co-polymer matrix assembled on the reduced graphene oxide (RGO) electrode surface. The cTnT active sites were engineered using pyrrole and carboxylated pyrrole that was one-step electropolymerized jointly with cTnT by cyclic voltammetry. The stepwise preparation of the biomimetic surface was characterized by cyclic and differential pulse voltammetries using the ferrocyanide/ferricyanide as redox probe. Structural and morphological characterization was also performed. The optimal relation of pyrrole and pyrrole-3-acid carboxylic to perform the cTnT biomimetic nanosurface was obtained at 1:5 ratio. The analytical performance of cTnT N-MIP performed by differential pulse voltammetry showed a linear range from 0.01 to 0.1 ng mL−1 (r=0.995, p«0.01), with a very low limit of detection (0.006 ng mL−1). The synergic effect of conductive polymer and graphene forming 3D structures of reactive sites resulted in a N-MIP with excellent affinity to cTnT binding (KD=7.3 10−13 mol L−1). The N-MIP proposed is based on a simple method of antibody obtaining with a large potential for point-of-care testing applications.}, keywords = {}, pubstate = {published}, tppubtype = {article} } A nano-molecularly imprinted polymer (N-MIP) assembled on a screen-printed electrode for the cardiac troponin T (cTnT) was developed. The biomimetic surface was obtained by a co-polymer matrix assembled on the reduced graphene oxide (RGO) electrode surface. The cTnT active sites were engineered using pyrrole and carboxylated pyrrole that was one-step electropolymerized jointly with cTnT by cyclic voltammetry. The stepwise preparation of the biomimetic surface was characterized by cyclic and differential pulse voltammetries using the ferrocyanide/ferricyanide as redox probe. Structural and morphological characterization was also performed. The optimal relation of pyrrole and pyrrole-3-acid carboxylic to perform the cTnT biomimetic nanosurface was obtained at 1:5 ratio. The analytical performance of cTnT N-MIP performed by differential pulse voltammetry showed a linear range from 0.01 to 0.1 ng mL−1 (r=0.995, p«0.01), with a very low limit of detection (0.006 ng mL−1). The synergic effect of conductive polymer and graphene forming 3D structures of reactive sites resulted in a N-MIP with excellent affinity to cTnT binding (KD=7.3 10−13 mol L−1). The N-MIP proposed is based on a simple method of antibody obtaining with a large potential for point-of-care testing applications. |
TSCR Rebelo, CM Pereira, MGF Sales, JPC Noronha, F Silva Protein imprinted materials designed with charged binding sites on screen-printed electrode for microseminoprotein-β determination in biological samples (Journal Article) Sensors and Actuators B: Chemical, 223 , pp. 846-852, 2016. @article{Rebelo2016, title = {Protein imprinted materials designed with charged binding sites on screen-printed electrode for microseminoprotein-β determination in biological samples}, author = {TSCR Rebelo and CM Pereira and MGF Sales and JPC Noronha and F Silva}, url = {http://www.sciencedirect.com/science/article/pii/S092540051530441X}, doi = {10.1016/j.snb.2015.09.133}, year = {2016}, date = {2016-02-29}, journal = {Sensors and Actuators B: Chemical}, volume = {223}, pages = {846-852}, abstract = {In the past few years a large effort is being made aiming at the development of fast and reliable tests for cancer biomarkers. Protein imprinted sensors can be a fast and reliable strategy to develop tailor made sensors for a large number of relevant molecules. This work aims to produce, optimize and use in biological samples a biosensor for microseminoprotein-beta (MSMB). Caffeic acid (CAF) electropolimerization was performed in the presence of microseminoprotein-beta (MSMB) creating target protein specific cavities on the surface of a screen-printed carbon. Dopamine was introduced as charged monomer labelling the binding site and was allowed to self-organize around the protein. The subsequent electropolimerization was made by applying a constant potential of +2.0 V, for 30 s, on a carbon screen-printed electrode, immersed in a solution of protein and CAF prepared in phosphate buffer. The sensor with charged monomers showed a more sensitive response, with an average slope of −7.59 μA/decade, linear concentration range of 0.5–100 ng/mL and a detection limit of 0.12 ng/mL. The corresponding non-imprinted sensor displayed an inconsistent response over the range of the calibration curve. The biosensor was successfully applied to the analysis of MSMB in serum and urine samples. }, keywords = {}, pubstate = {published}, tppubtype = {article} } In the past few years a large effort is being made aiming at the development of fast and reliable tests for cancer biomarkers. Protein imprinted sensors can be a fast and reliable strategy to develop tailor made sensors for a large number of relevant molecules. This work aims to produce, optimize and use in biological samples a biosensor for microseminoprotein-beta (MSMB). Caffeic acid (CAF) electropolimerization was performed in the presence of microseminoprotein-beta (MSMB) creating target protein specific cavities on the surface of a screen-printed carbon. Dopamine was introduced as charged monomer labelling the binding site and was allowed to self-organize around the protein. The subsequent electropolimerization was made by applying a constant potential of +2.0 V, for 30 s, on a carbon screen-printed electrode, immersed in a solution of protein and CAF prepared in phosphate buffer. The sensor with charged monomers showed a more sensitive response, with an average slope of −7.59 μA/decade, linear concentration range of 0.5–100 ng/mL and a detection limit of 0.12 ng/mL. The corresponding non-imprinted sensor displayed an inconsistent response over the range of the calibration curve. The biosensor was successfully applied to the analysis of MSMB in serum and urine samples. |
FTC Moreira, MJMS Ferreira, JRT Puga, MGF Sales Screen-printed electrode produced by printed-circuit board technology. Application to cancer biomarker detection by means of plastic antibody as sensing material (Journal Article) Sensors and Actuators B: Chemical, 223 , pp. 927–935, 2016. @article{Moreira2016, title = {Screen-printed electrode produced by printed-circuit board technology. Application to cancer biomarker detection by means of plastic antibody as sensing material}, author = {FTC Moreira and MJMS Ferreira and JRT Puga and MGF Sales}, url = {http://www.sciencedirect.com/science/article/pii/S0925400515304640}, doi = {10.1016/j.snb.2015.09.157}, year = {2016}, date = {2016-02-01}, journal = {Sensors and Actuators B: Chemical}, volume = {223}, pages = {927–935}, abstract = {This research work presents, for the first time, a screen-printed electrode (SPE) made on a PCB board with silver tracks (Ag) and a three electrode configuration (AgxO-working, AgxO-counter and Ag/AgxO-reference electrodes), following the same approach as printed-circuit boards (PCBs). This low cost and disposable device was tested for screening a cancer biomarker in point-of-care. The selected biomarker was carcinogenic embryonic antigen (CEA) protein, routinely used to follow-up the progression of specific cancer diseases. The biosensor was constructed by assembling a plastic antibody on the Ag-working electrode area, acting as the biorecognition element of the device. The protein molecules that were entrapped on the polymer and positioned at the outer surface of the polypyrrole (PPy) film were removed by protease action. The imprinting effect was tested by preparing non-imprinted (NPPy) material, including only PPy as biorecognition element. Infrared and Raman studies confirmed the surface modification of these electrodes. The ability of the sensing material to rebind CEA was measured by several electrochemical techniques: cyclic voltammetry (CV), impedance spectroscopy (EIS) and square wave voltammetry (SWV). The linear response ranged from 0.05 to 1.25 pg/mL against logarithm concentration. Overall, producing screen-printed electrodes by means of conventional PCB technology showed promising features, mostly regarding cost and prompt availability. The plastic antibody-based biosensor also seems to be a promising tool for screening CEA in point-of-care, with low response time, low cost, good sensitivity and high stability.}, keywords = {}, pubstate = {published}, tppubtype = {article} } This research work presents, for the first time, a screen-printed electrode (SPE) made on a PCB board with silver tracks (Ag) and a three electrode configuration (AgxO-working, AgxO-counter and Ag/AgxO-reference electrodes), following the same approach as printed-circuit boards (PCBs). This low cost and disposable device was tested for screening a cancer biomarker in point-of-care. The selected biomarker was carcinogenic embryonic antigen (CEA) protein, routinely used to follow-up the progression of specific cancer diseases. The biosensor was constructed by assembling a plastic antibody on the Ag-working electrode area, acting as the biorecognition element of the device. The protein molecules that were entrapped on the polymer and positioned at the outer surface of the polypyrrole (PPy) film were removed by protease action. The imprinting effect was tested by preparing non-imprinted (NPPy) material, including only PPy as biorecognition element. Infrared and Raman studies confirmed the surface modification of these electrodes. The ability of the sensing material to rebind CEA was measured by several electrochemical techniques: cyclic voltammetry (CV), impedance spectroscopy (EIS) and square wave voltammetry (SWV). The linear response ranged from 0.05 to 1.25 pg/mL against logarithm concentration. Overall, producing screen-printed electrodes by means of conventional PCB technology showed promising features, mostly regarding cost and prompt availability. The plastic antibody-based biosensor also seems to be a promising tool for screening CEA in point-of-care, with low response time, low cost, good sensitivity and high stability. |
TSCR Rebelo, JPC Noronha, M Galésio, H Santos, M Diniz, MGF Sales, MH Fernandes, J Costa-Rodrigues Materials Science and Engineering: C, 59 , pp. 1069–1078, 2016. @article{Rebelo2016b, title = {Testing the variability of PSA expression by different human prostate cancer cell lines by means of a new potentiometric device employing molecularly antibody assembled on graphene surface}, author = {TSCR Rebelo and JPC Noronha and M Galésio and H Santos and M Diniz and MGF Sales and MH Fernandes and J Costa-Rodrigues}, url = {http://www.sciencedirect.com/science/article/pii/S0928493115305634}, doi = {10.1016/j.msec.2015.11.032}, year = {2016}, date = {2016-02-01}, journal = {Materials Science and Engineering: C}, volume = {59}, pages = {1069–1078}, abstract = {Prostate Specific Antigen (PSA) is widely used as a biomarker for prostate cancer. Recently, an electrochemical biosensor for PSA detection by means of molecularly imprinted polymers (MIPs) was developed. This work evaluated the performance and the effectiveness of that PSA biosensor in screening the biomarker PSA in biological media with complex composition, collected from different human prostate cell line cultures. For that, the prostate cancer LNCaP and PC3 cells, and the non-cancerous prostate cell line PNT2 were cultured for 2, 7 and 14 days in either α-MEM or RPMI in the presence of 10% or 30% fetal bovine serum. Human gingival fibroblasts were used as a non-cancerous non-prostatic control. The different culture conditions modulated cellular proliferation and the expression of several prostate markers, including PSA. The electrochemical biosensor was able to specifically detect PSA in the culture media and values obtained were similar to those achieved by a commercial Enzyme-Linked Immunosorbent Assay (ELISA) kit, the most commonly used method for PSA quantification in prostate cancer diagnosis. Thus, the tested biosensor may represent a useful alternative as a diagnostic tool for PSA determination in biological samples.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Prostate Specific Antigen (PSA) is widely used as a biomarker for prostate cancer. Recently, an electrochemical biosensor for PSA detection by means of molecularly imprinted polymers (MIPs) was developed. This work evaluated the performance and the effectiveness of that PSA biosensor in screening the biomarker PSA in biological media with complex composition, collected from different human prostate cell line cultures. For that, the prostate cancer LNCaP and PC3 cells, and the non-cancerous prostate cell line PNT2 were cultured for 2, 7 and 14 days in either α-MEM or RPMI in the presence of 10% or 30% fetal bovine serum. Human gingival fibroblasts were used as a non-cancerous non-prostatic control. The different culture conditions modulated cellular proliferation and the expression of several prostate markers, including PSA. The electrochemical biosensor was able to specifically detect PSA in the culture media and values obtained were similar to those achieved by a commercial Enzyme-Linked Immunosorbent Assay (ELISA) kit, the most commonly used method for PSA quantification in prostate cancer diagnosis. Thus, the tested biosensor may represent a useful alternative as a diagnostic tool for PSA determination in biological samples. |
JRL Guerreiro, VE Bochenkov, K Runager, H Aslan, M Dong, JJ Enghild, VAP Freitas, MGF Sales, DS Sutherland Molecular imprinting of complex matrices at localized surface plasmon resonance biosensors for screening of global interactions of polyphenols and proteins (Journal Article) Acs Sensors, 1 , pp. 258-264, 2016. @article{Guerreiro2016, title = {Molecular imprinting of complex matrices at localized surface plasmon resonance biosensors for screening of global interactions of polyphenols and proteins}, author = {JRL Guerreiro and VE Bochenkov and K Runager and H Aslan and M Dong and JJ Enghild and VAP Freitas and MGF Sales and DS Sutherland}, url = {http://pubs.acs.org/doi/abs/10.1021/acssensors.5b00054}, doi = {10.1021/acssensors.5b00054}, year = {2016}, date = {2016-01-06}, journal = {Acs Sensors}, volume = {1}, pages = {258-264}, abstract = {Molecular imprinting polymers (MIP) have been applied to capture and stabilize complex protein matrices at plasmonic sensor surfaces. Ultrathin MIP layers at the surface of gold nanodisks enable the label free quantification of global interactions of polyphenols with protein mixtures. Separate polyphenols (catechin, procyanidin B3- catechin dimer, and PGG-pentagalloyl glucose) give specific and different binding levels to the MIP supported saliva plasmonic sensor. The demonstrated biosensor has application to study bioavailability of polyphenols or evaluation of local retention of small drug molecules.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Molecular imprinting polymers (MIP) have been applied to capture and stabilize complex protein matrices at plasmonic sensor surfaces. Ultrathin MIP layers at the surface of gold nanodisks enable the label free quantification of global interactions of polyphenols with protein mixtures. Separate polyphenols (catechin, procyanidin B3- catechin dimer, and PGG-pentagalloyl glucose) give specific and different binding levels to the MIP supported saliva plasmonic sensor. The demonstrated biosensor has application to study bioavailability of polyphenols or evaluation of local retention of small drug molecules. |
2015
LAANA Truta, MGF Sales Sol-gel chemistry in biosensing devices of electrical transduction: Application to CEA cancer biomarker (Journal Article) Current Topics in Medicinal Chemistry, 15 (3), pp. 256-261, 2015, ISSN: 1568-0266. @article{Truta2015, title = {Sol-gel chemistry in biosensing devices of electrical transduction: Application to CEA cancer biomarker}, author = {LAANA Truta and MGF Sales}, url = {http://www.eurekaselect.com/127192/article http://recipp.ipp.pt/handle/10400.22/6721}, doi = {10.2174/1568026614666141229113318}, issn = {1568-0266}, year = {2015}, date = {2015-12-01}, journal = {Current Topics in Medicinal Chemistry}, volume = {15}, number = {3}, pages = {256-261}, abstract = {Sol-gel chemistry allows the immobilization of organic molecules of biological origin on suibtable solid supports, permitting their integration into biosensing devices widening the possibility of local applications. The present work is an application of this principle, where the link between electrical receptor platform and the antibody acting as biorecognition element is made by sol-gel chemistry. The immunosensor design was targeted for carcinoembryonic antigen (CEA), an important biomarker for screening the colorectal cancer, by electrochemical techniques, namely electrochemical impedance spectroscopy (EIS) and square wave voltammetry (SVW). The device displayed linear behavior to CEA in EIS and in SWV assays ranging from 0.50 to 1.5ng/mL, and 0.25 to 1.5ng/mL, respectively. The corresponding detection limits were 0.42 and 0.043 ng/mL. Raman spectroscopy was used to characterize the surface modifications on the conductive platform (FTO glass). Overall, simple sol-gel chemistry was effective at the biosensing design and the presented approach can be a potential method for screening CEA in point-of-care, due to the simplicity of fabrication, short response time and low cost.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Sol-gel chemistry allows the immobilization of organic molecules of biological origin on suibtable solid supports, permitting their integration into biosensing devices widening the possibility of local applications. The present work is an application of this principle, where the link between electrical receptor platform and the antibody acting as biorecognition element is made by sol-gel chemistry. The immunosensor design was targeted for carcinoembryonic antigen (CEA), an important biomarker for screening the colorectal cancer, by electrochemical techniques, namely electrochemical impedance spectroscopy (EIS) and square wave voltammetry (SVW). The device displayed linear behavior to CEA in EIS and in SWV assays ranging from 0.50 to 1.5ng/mL, and 0.25 to 1.5ng/mL, respectively. The corresponding detection limits were 0.42 and 0.043 ng/mL. Raman spectroscopy was used to characterize the surface modifications on the conductive platform (FTO glass). Overall, simple sol-gel chemistry was effective at the biosensing design and the presented approach can be a potential method for screening CEA in point-of-care, due to the simplicity of fabrication, short response time and low cost. |
FTC Moreira, APM Tavares, MGF Sales Sol-gel-based biosensing applied to medicinal science (Journal Article) Current Topics in Medicinal Chemistry, 15 (3), pp. 245-255, 2015. @article{Moreira2015b, title = {Sol-gel-based biosensing applied to medicinal science}, author = {FTC Moreira and APM Tavares and MGF Sales}, url = {http://www.eurekaselect.com/127191/article http://recipp.ipp.pt/handle/10400.22/6719}, doi = {10.2174/1568026614666141229113012}, year = {2015}, date = {2015-12-01}, journal = {Current Topics in Medicinal Chemistry}, volume = {15}, number = {3}, pages = {245-255}, abstract = {Biosensors have opened new horizons in biomedical analysis, by ensuring increased assay speed and flexibility, and allowing point-of-care applications, multi-target analyses, automation and reduced costs of testing. This has been a result of many studies merging nanotechnology with biochemistry over the years, thereby enabling the creation of more suitable environments to biological receptors and their substitution by synthetic analogue materials. Sol-gel chemistry, among other materials, is deeply involved in this process. Sol-gel processing allows the immobilization of organic molecules, biomacromolecules and cells maintaining their properties and activities, permitting their integration into different transduction devices, of electrochemical or optical nature, for single or multiple analyses. Sol-gel also allows to the production of synthetic materials mimicking the activity of natural receptors, while bringing advantages, mostly in terms of cost and stability. Moreover, the biocompatibility of sol-gel materials structures of biological nature allowed the use of these materials in emerging in vivo applications. In this chapter, biosensors for biomedical applications based on sol-gel derived composites are presented, compared and described, along with current emerging applications in vivo, concerning drug delivery or biomaterials. Sol-gel materials are shown as a promising tool for current, emerging and future medical applications.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Biosensors have opened new horizons in biomedical analysis, by ensuring increased assay speed and flexibility, and allowing point-of-care applications, multi-target analyses, automation and reduced costs of testing. This has been a result of many studies merging nanotechnology with biochemistry over the years, thereby enabling the creation of more suitable environments to biological receptors and their substitution by synthetic analogue materials. Sol-gel chemistry, among other materials, is deeply involved in this process. Sol-gel processing allows the immobilization of organic molecules, biomacromolecules and cells maintaining their properties and activities, permitting their integration into different transduction devices, of electrochemical or optical nature, for single or multiple analyses. Sol-gel also allows to the production of synthetic materials mimicking the activity of natural receptors, while bringing advantages, mostly in terms of cost and stability. Moreover, the biocompatibility of sol-gel materials structures of biological nature allowed the use of these materials in emerging in vivo applications. In this chapter, biosensors for biomedical applications based on sol-gel derived composites are presented, compared and described, along with current emerging applications in vivo, concerning drug delivery or biomaterials. Sol-gel materials are shown as a promising tool for current, emerging and future medical applications. |
FTC Moreira, S Sharma, RAF Dutra, JPC Noronha, AEG Cass, MGF Sales Detection of cardiac biomarker proteins using a disposable based on a molecularly imprinted polymer grafted onto graphite (Journal Article) Microchimica Acta, 182 (5), pp. 975-983, 2015, ISSN: 0026-3672. @article{Moreira2015, title = {Detection of cardiac biomarker proteins using a disposable based on a molecularly imprinted polymer grafted onto graphite}, author = {FTC Moreira and S Sharma and RAF Dutra and JPC Noronha and AEG Cass and MGF Sales}, url = {http://link.springer.com/article/10.1007%2Fs00604-014-1409-0 http://recipp.ipp.pt/handle/10400.22/6720}, doi = {10.1007/s00604-014-1409-0}, issn = {0026-3672}, year = {2015}, date = {2015-04-01}, journal = {Microchimica Acta}, volume = {182}, number = {5}, pages = {975-983}, abstract = {A low-cost disposable was developed for rapid detection of the protein biomarker myoglobin (Myo) as a model analyte. A screen printed electrode was modified with a molecularly imprinted material grafted on a graphite support and incorporated in a matrix composed of poly(vinyl chloride) and the plasticizer o-nitrophenyloctyl ether. The protein-imprinted material (PIM) was produced by growing a reticulated polymer around a protein template. This is followed by radical polymerization of 4-styrenesulfonic acid, 2-aminoethyl methacrylate hydrochloride, and ethylene glycol dimethacrylate. The polymeric layer was then covalently bound to the graphitic support, and Myo was added during the imprinting stage to act as a template. Non-imprinted control materials (CM) were also prepared by omitting the Myo template. Morphological and structural analysis of PIM and CM by FTIR, Raman, and SEM/EDC microscopies confirmed the modification of the graphite support. The analytical performance of the SPE was assessed by square wave voltammetry. The average limit of detection is 0.79 μg of Myo per mL, and the slope is −0.193 ± 0.006 μA per decade. The SPE-CM cannot detect such low levels of Myo but gives a linear response at above 7.2 μg · mL−1, with a slope of −0.719 ± 0.02 μA per decade. Interference studies with hemoglobin, bovine serum albumin, creatinine, and sodium chloride demonstrated good selectivity for Myo. The method was successfully applied to the determination of Myo urine and is conceived to be a promising tool for screening Myo in point-of-care patients with ischemia.}, keywords = {}, pubstate = {published}, tppubtype = {article} } A low-cost disposable was developed for rapid detection of the protein biomarker myoglobin (Myo) as a model analyte. A screen printed electrode was modified with a molecularly imprinted material grafted on a graphite support and incorporated in a matrix composed of poly(vinyl chloride) and the plasticizer o-nitrophenyloctyl ether. The protein-imprinted material (PIM) was produced by growing a reticulated polymer around a protein template. This is followed by radical polymerization of 4-styrenesulfonic acid, 2-aminoethyl methacrylate hydrochloride, and ethylene glycol dimethacrylate. The polymeric layer was then covalently bound to the graphitic support, and Myo was added during the imprinting stage to act as a template. Non-imprinted control materials (CM) were also prepared by omitting the Myo template. Morphological and structural analysis of PIM and CM by FTIR, Raman, and SEM/EDC microscopies confirmed the modification of the graphite support. The analytical performance of the SPE was assessed by square wave voltammetry. The average limit of detection is 0.79 μg of Myo per mL, and the slope is −0.193 ± 0.006 μA per decade. The SPE-CM cannot detect such low levels of Myo but gives a linear response at above 7.2 μg · mL−1, with a slope of −0.719 ± 0.02 μA per decade. Interference studies with hemoglobin, bovine serum albumin, creatinine, and sodium chloride demonstrated good selectivity for Myo. The method was successfully applied to the determination of Myo urine and is conceived to be a promising tool for screening Myo in point-of-care patients with ischemia. |
HIAS Gomes, MGF Sales Development of paper-based color test-strip for drug detection in aquatic environment: Application to oxytetracycline (Journal Article) Biosensors and Bioelectronics, 65 , pp. 54–61, 2015. @article{Gomes2015, title = {Development of paper-based color test-strip for drug detection in aquatic environment: Application to oxytetracycline}, author = {HIAS Gomes and MGF Sales}, url = {http://www.sciencedirect.com/science/article/pii/S0956566314007908 }, doi = {10.1016/j.bios.2014.10.006}, year = {2015}, date = {2015-03-15}, journal = {Biosensors and Bioelectronics}, volume = {65}, pages = {54–61}, abstract = {The wide use of antibiotics in aquaculture has led to the emergence of resistant microbial species. It should be avoided/minimized by controlling the amount of drug employed in fish farming. For this purpose, the present work proposes test-strip papers aiming at the detection/semi-quantitative determination of organic drugs by visual comparison of color changes, in a similar analytical procedure to that of pH monitoring by universal pH paper. This is done by establishing suitable chemical changes upon cellulose, attributing the paper the ability to react with the organic drug and to produce a color change. Quantitative data is also enabled by taking a picture and applying a suitable mathematical treatment to the color coordinates given by the HSL system used by windows. As proof of concept, this approach was applied to oxytetracycline (OXY), one of the antibiotics frequently used in aquaculture. A bottom-up modification of paper was established, starting by the reaction of the glucose moieties on the paper with 3-triethoxysilylpropylamine (APTES). The so-formed amine layer allowed binding to a metal ion by coordination chemistry, while the metal ion reacted after with the drug to produce a colored compound. The most suitable metals to carry out such modification were selected by bulk studies, and the several stages of the paper modification were optimized to produce an intense color change against the concentration of the drug. The paper strips were applied to the analysis of spiked environmental water, allowing a quantitative determination for OXY concentrations as low as 30 ng/mL. In general, this work provided a simple, method to screen and discriminate tetracycline drugs, in aquaculture, being a promising tool for local, quick and cheap monitoring of drugs.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The wide use of antibiotics in aquaculture has led to the emergence of resistant microbial species. It should be avoided/minimized by controlling the amount of drug employed in fish farming. For this purpose, the present work proposes test-strip papers aiming at the detection/semi-quantitative determination of organic drugs by visual comparison of color changes, in a similar analytical procedure to that of pH monitoring by universal pH paper. This is done by establishing suitable chemical changes upon cellulose, attributing the paper the ability to react with the organic drug and to produce a color change. Quantitative data is also enabled by taking a picture and applying a suitable mathematical treatment to the color coordinates given by the HSL system used by windows. As proof of concept, this approach was applied to oxytetracycline (OXY), one of the antibiotics frequently used in aquaculture. A bottom-up modification of paper was established, starting by the reaction of the glucose moieties on the paper with 3-triethoxysilylpropylamine (APTES). The so-formed amine layer allowed binding to a metal ion by coordination chemistry, while the metal ion reacted after with the drug to produce a colored compound. The most suitable metals to carry out such modification were selected by bulk studies, and the several stages of the paper modification were optimized to produce an intense color change against the concentration of the drug. The paper strips were applied to the analysis of spiked environmental water, allowing a quantitative determination for OXY concentrations as low as 30 ng/mL. In general, this work provided a simple, method to screen and discriminate tetracycline drugs, in aquaculture, being a promising tool for local, quick and cheap monitoring of drugs. |
2014
LAANA Truta, NS Ferreira, MGF Sales Electrochimica Acta, 150 , pp. 99–107, 2014. @article{Truta2014, title = {Graphene-based biomimetic materials targeting urine metabolite as potential cancer biomarker: Application over different conductive materials for potentiometric transduction}, author = {LAANA Truta and NS Ferreira and MGF Sales}, url = {http://www.sciencedirect.com/science/article/pii/S0013468614021574 http://recipp.ipp.pt/handle/10400.22/6717}, doi = {10.1016/j.electacta.2014.10.136}, year = {2014}, date = {2014-12-20}, journal = {Electrochimica Acta}, volume = {150}, pages = {99–107}, abstract = {This work presents a novel surface Smart Polymer Antibody Material (SPAM) for Carnitine (CRT, a potential biomarker of ovarian cancer), tested for the first time as ionophore in potentiometric electrodes of unconventional configuration. The SPAM material consisted of a 3D polymeric network created by surface imprinting on graphene layers. The polymer was obtained by radical polymerization of (vinylbenzyl) trimethylammonium chloride and 4-styrenesulfonic acid (signaling the binding sites), and vinyl pivalate and ethylene glycol dimethacrylate (surroundings). Non-imprinted material (NIM) was prepared as control, by excluding the template from the procedure. These materials were then used to produce several plasticized PVC membranes, testing the relevance of including the SPAM as ionophore, and the need for a charged lipophilic additive. The membranes were casted over solid conductive supports of graphite or ITO/FTO. The effect of pH upon the potentiometric response was evaluated for different pHs (2-9) with different buffer compositions. Overall, the best performance was achieved for membranes with SPAM ionophore, having a cationic lipophilic additive and tested in HEPES (4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid) buffer, pH 5.1. Better slopes were achieved when the membrane was casted on conductive glass (-57.4 mV/decade), while the best detection limits were obtained for graphite-based conductive supports (3.6 × 10−5mol/L). Good selectivity was observed against BSA, ascorbic acid, glucose, creatinine and urea, tested for concentrations up to their normal physiologic levels in urine. The application of the devices to the analysis of spiked samples showed recoveries ranging from 91% (± 6.8%) to 118% (± 11.2%). Overall, the combination of the SPAM sensory material with a suitable selective membrane composition and electrode design has lead to a promising tool for point-of-care applications.}, keywords = {}, pubstate = {published}, tppubtype = {article} } This work presents a novel surface Smart Polymer Antibody Material (SPAM) for Carnitine (CRT, a potential biomarker of ovarian cancer), tested for the first time as ionophore in potentiometric electrodes of unconventional configuration. The SPAM material consisted of a 3D polymeric network created by surface imprinting on graphene layers. The polymer was obtained by radical polymerization of (vinylbenzyl) trimethylammonium chloride and 4-styrenesulfonic acid (signaling the binding sites), and vinyl pivalate and ethylene glycol dimethacrylate (surroundings). Non-imprinted material (NIM) was prepared as control, by excluding the template from the procedure. These materials were then used to produce several plasticized PVC membranes, testing the relevance of including the SPAM as ionophore, and the need for a charged lipophilic additive. The membranes were casted over solid conductive supports of graphite or ITO/FTO. The effect of pH upon the potentiometric response was evaluated for different pHs (2-9) with different buffer compositions. Overall, the best performance was achieved for membranes with SPAM ionophore, having a cationic lipophilic additive and tested in HEPES (4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid) buffer, pH 5.1. Better slopes were achieved when the membrane was casted on conductive glass (-57.4 mV/decade), while the best detection limits were obtained for graphite-based conductive supports (3.6 × 10−5mol/L). Good selectivity was observed against BSA, ascorbic acid, glucose, creatinine and urea, tested for concentrations up to their normal physiologic levels in urine. The application of the devices to the analysis of spiked samples showed recoveries ranging from 91% (± 6.8%) to 118% (± 11.2%). Overall, the combination of the SPAM sensory material with a suitable selective membrane composition and electrode design has lead to a promising tool for point-of-care applications. |
S Teixeira, NS Ferreira, RS Conlan, OJ Guy, MGF Sales Chitosan/AuNPs modified graphene electrochemical sensor for label‐free human chorionic gonadotropin detection (Journal Article) Electroanalysis, 26 (12), pp. 2591–2598, 2014. @article{Teixeira2014b, title = {Chitosan/AuNPs modified graphene electrochemical sensor for label‐free human chorionic gonadotropin detection}, author = {S Teixeira and NS Ferreira and RS Conlan and OJ Guy and MGF Sales}, url = {http://onlinelibrary.wiley.com/doi/10.1002/elan.201400311/abstract http://recipp.ipp.pt/handle/10400.22/6701}, doi = {10.1002/elan.201400311}, year = {2014}, date = {2014-12-01}, journal = {Electroanalysis}, volume = {26}, number = {12}, pages = {2591–2598}, abstract = {A new immunosensor is presented for human chorionic gonadotropin (hCG), made by electrodepositing chitosan/gold-nanoparticles over graphene screen-printed electrode (SPE). The antibody was covalently bound to CS via its Fc-terminal. The assembly was controlled by electrochemical Impedance Spectroscopy (EIS) and followed by Fourier Transformed Infrared (FTIR). The hCG-immunosensor displayed linear response against the logarithm-hCG concentration for 0.1–25 ng/mL with limit of detection of 0.016 ng/mL. High selectivity was observed in blank urine and successful detection of hCG was also achieved in spiked samples of real urine from pregnant woman. The immunosensor showed good detection capability, simplicity of fabrication, low-cost, high sensitivity and selectivity.}, keywords = {}, pubstate = {published}, tppubtype = {article} } A new immunosensor is presented for human chorionic gonadotropin (hCG), made by electrodepositing chitosan/gold-nanoparticles over graphene screen-printed electrode (SPE). The antibody was covalently bound to CS via its Fc-terminal. The assembly was controlled by electrochemical Impedance Spectroscopy (EIS) and followed by Fourier Transformed Infrared (FTIR). The hCG-immunosensor displayed linear response against the logarithm-hCG concentration for 0.1–25 ng/mL with limit of detection of 0.016 ng/mL. High selectivity was observed in blank urine and successful detection of hCG was also achieved in spiked samples of real urine from pregnant woman. The immunosensor showed good detection capability, simplicity of fabrication, low-cost, high sensitivity and selectivity. |
TSCR Rebelo, CM Pereira, MGF Sales, JPC Noronha, J Costa-Rodrigues, F Silva, MH Fernandes Sarcosine oxidase composite screen-printed electrode for sarcosine determination in biological samples (Journal Article) Analytica Chimica Acta, 850 , pp. 26–32, 2014. @article{Rebelo2014b, title = {Sarcosine oxidase composite screen-printed electrode for sarcosine determination in biological samples}, author = {TSCR Rebelo and CM Pereira and MGF Sales and JPC Noronha and J Costa-Rodrigues and F Silva and MH Fernandes}, url = {http://www.sciencedirect.com/science/article/pii/S0003267014009520 http://recipp.ipp.pt/handle/10400.22/6698}, doi = {10.1016/j.aca.2014.08.005}, year = {2014}, date = {2014-11-19}, journal = {Analytica Chimica Acta}, volume = {850}, pages = {26–32}, abstract = {As the prostate cancer (PCa) progresses, sarcosine levels increase both in tumor cells and urine samples, suggesting that this metabolite measurements can help in the creation of non-invasive diagnostic methods for this disease. In this work, a biosensor device was developed for the quantification of sarcosine via electrochemical detection of H2O2 (at 0.6 V) generated from the catalyzed oxidation of sarcosine. The detection was carried out after the modification of carbon screen printed electrodes (SPEs) by immobilization of sarcosine oxidase (SOX) on the electrode surface. The strategies used herein included the activation of the carbon films by an electrochemical step and the formation of an NHS/EDAC layer to bond the enzyme to the electrode, the use of metallic or semiconductor nanoparticles layer previously or during the enzyme immobilization. In order to improve the sensor stability and selectivity a polymeric layer with extra enzyme content was further added. The proposed methodology for the detection of sarcosine allowed obtaining a limit of detection (LOD) of 16 nM, using a linear concentration range between 10 and 100 nM. The biosensor was successfully applied to the analysis of sarcosine in urine samples.}, keywords = {}, pubstate = {published}, tppubtype = {article} } As the prostate cancer (PCa) progresses, sarcosine levels increase both in tumor cells and urine samples, suggesting that this metabolite measurements can help in the creation of non-invasive diagnostic methods for this disease. In this work, a biosensor device was developed for the quantification of sarcosine via electrochemical detection of H2O2 (at 0.6 V) generated from the catalyzed oxidation of sarcosine. The detection was carried out after the modification of carbon screen printed electrodes (SPEs) by immobilization of sarcosine oxidase (SOX) on the electrode surface. The strategies used herein included the activation of the carbon films by an electrochemical step and the formation of an NHS/EDAC layer to bond the enzyme to the electrode, the use of metallic or semiconductor nanoparticles layer previously or during the enzyme immobilization. In order to improve the sensor stability and selectivity a polymeric layer with extra enzyme content was further added. The proposed methodology for the detection of sarcosine allowed obtaining a limit of detection (LOD) of 16 nM, using a linear concentration range between 10 and 100 nM. The biosensor was successfully applied to the analysis of sarcosine in urine samples. |
J Moret, FTC Moreira, SAA Almeida, MGF Sales New molecularly-imprinted polymer for carnitine and its application as ionophore in potentiometric selective membranes (Journal Article) Materials Science and Engineering: C, 43 , pp. 481–487, 2014. @article{Moret2014, title = {New molecularly-imprinted polymer for carnitine and its application as ionophore in potentiometric selective membranes}, author = {J Moret and FTC Moreira and SAA Almeida and MGF Sales}, url = {http://www.sciencedirect.com/science/article/pii/S0928493114004640 http://recipp.ipp.pt/handle/10400.22/6718}, doi = {10.1016/j.msec.2014.07.056}, year = {2014}, date = {2014-10-01}, journal = {Materials Science and Engineering: C}, volume = {43}, pages = {481–487}, abstract = {Carnitine (CRT) is a biological metabolite found in urine that contributes in assessingseveral disease conditions, including cancer. Novel quick screening procedures for CRT are therefore fundamental. This work proposes a novel potentiometric device where molecularly imprinted polymers (MIPs) were used as ionophores. The host-tailored sites were imprinted on a polymeric network assembled by radical polymerization of methacrylic acid (MAA) and trimethylpropane trimethacrylate (TRIM). Non-imprinted polymers (NIPs) were produced as control by removing the template from the reaction media. The selective membrane was prepared by dispersing MIP or NIP particles in plasticizer and poly(vinyl chloride), PVC, and casting this mixture over a solid contact support made of graphite. The composition of the selective membrane was investigated with regard to kind/amount of sensory material (MIP or NIP), and the need for a lipophilic additive. Overall, MIP sensors with additive exhibited the best performance, with near-Nernstian response down to ~1×10(-4)mol L(-1), at pH5, and a detection limit of ~8×10(-5)mol L(-1). Suitable selectivity was found for all membranes, assessed by the matched potential method against some of the most common species in urine (urea, sodium, creatinine, sulfate, fructose and hemoglobin). CRT selective membranes including MIP materials were applied successfully to the potentiometric determination of CRT in urine samples.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Carnitine (CRT) is a biological metabolite found in urine that contributes in assessingseveral disease conditions, including cancer. Novel quick screening procedures for CRT are therefore fundamental. This work proposes a novel potentiometric device where molecularly imprinted polymers (MIPs) were used as ionophores. The host-tailored sites were imprinted on a polymeric network assembled by radical polymerization of methacrylic acid (MAA) and trimethylpropane trimethacrylate (TRIM). Non-imprinted polymers (NIPs) were produced as control by removing the template from the reaction media. The selective membrane was prepared by dispersing MIP or NIP particles in plasticizer and poly(vinyl chloride), PVC, and casting this mixture over a solid contact support made of graphite. The composition of the selective membrane was investigated with regard to kind/amount of sensory material (MIP or NIP), and the need for a lipophilic additive. Overall, MIP sensors with additive exhibited the best performance, with near-Nernstian response down to ~1×10(-4)mol L(-1), at pH5, and a detection limit of ~8×10(-5)mol L(-1). Suitable selectivity was found for all membranes, assessed by the matched potential method against some of the most common species in urine (urea, sodium, creatinine, sulfate, fructose and hemoglobin). CRT selective membranes including MIP materials were applied successfully to the potentiometric determination of CRT in urine samples. |
JRL Guerreiro, M Frederiksen, VE Bochenkov, VAP Freitas, MGF Sales, DS Sutherland Multifunctional biosensor based on localized surface plasmon resonance for monitoring small molecule–protein interaction (Journal Article) ACS Nano, 8 (8), pp. 7958-7967, 2014. @article{Guerreiro2014, title = {Multifunctional biosensor based on localized surface plasmon resonance for monitoring small molecule–protein interaction}, author = {JRL Guerreiro and M Frederiksen and VE Bochenkov and VAP Freitas and MGF Sales and DS Sutherland}, url = {http://www.ncbi.nlm.nih.gov/pubmed/25003494 http://recipp.ipp.pt/handle/10400.22/6722}, doi = {10.1021/nn501962y}, year = {2014}, date = {2014-08-26}, journal = {ACS Nano}, volume = {8}, number = {8}, pages = {7958-7967}, abstract = {We report an optical sensor based on localized surface plasmon resonance (LSPR) to study small-molecule protein interaction combining high sensitivity refractive index sensing for quantitative binding information and subsequent conformation-sensitive plasmon-activated circular dichroism spectroscopy. The interaction of α-amylase and a small-size molecule (PGG, pentagalloyl glucose) was log concentration-dependent from 0.5 to 154 μM. In situ tests were additionally successfully applied to the analysis of real wine samples. These studies demonstrate that LSPR sensors to monitor small molecule–protein interactions in real time and in situ, which is a great advance within technological platforms for drug discovery.}, keywords = {}, pubstate = {published}, tppubtype = {article} } We report an optical sensor based on localized surface plasmon resonance (LSPR) to study small-molecule protein interaction combining high sensitivity refractive index sensing for quantitative binding information and subsequent conformation-sensitive plasmon-activated circular dichroism spectroscopy. The interaction of α-amylase and a small-size molecule (PGG, pentagalloyl glucose) was log concentration-dependent from 0.5 to 154 μM. In situ tests were additionally successfully applied to the analysis of real wine samples. These studies demonstrate that LSPR sensors to monitor small molecule–protein interactions in real time and in situ, which is a great advance within technological platforms for drug discovery. |
TSCR Rebelo, C Santos, J Costa-Rodrigues, MH Fernandes, JPC Noronha, MGF Sales Electrochimica Acta, 132 , pp. 142–150, 2014. @article{Rebelo2014, title = {Novel prostate specific antigen plastic antibody designed with charged binding sites for an improved protein binding and its application in a biosensor of potentiometric transduction}, author = {TSCR Rebelo and C Santos and J Costa-Rodrigues and MH Fernandes and JPC Noronha and MGF Sales }, url = {http://www.sciencedirect.com/science/article/pii/S0013468614006215 http://recipp.ipp.pt/handle/10400.22/6697}, doi = {10.1016/j.electacta.2014.03.108}, year = {2014}, date = {2014-06-20}, journal = {Electrochimica Acta}, volume = {132}, pages = {142–150}, abstract = {This work shows that the synthesis of protein plastic antibodies tailored with selected charged monomers around the binding site enhances protein binding. These charged receptor sites are placed over a neutral polymeric matrix, thus inducing a suitable orientation the protein reception to its site. This is confirmed by preparing control materials with neutral monomers and also with non-imprinted template. This concept has been applied here to Prostate Specific Antigen (PSA), the protein of choice for screening prostate cancer throughout the population, with serum levels >10 ng/mL pointing out a high probability of associated cancer. Protein Imprinted Materials with charged binding sites (C/PIM) have been produced by surface imprinting over graphene layers to which the protein was first covalently attached. Vinylbenzyl(trimethylammonium chloride) and vinyl benzoate were introduced as charged monomers labelling the binding site and were allowed to self-organize around the protein. The subsequent polymerization was made by radical polymerization of vinylbenzene. Neutral PIM (N/PIM) prepared without oriented charges and non imprinted materials (NIM) obtained without template were used as controls. These materials were used to develop simple and inexpensive potentiometric sensor for PSA. They were included as ionophores in plasticized PVC membranes, and tested over electrodes of solid or liquid conductive contacts, made of conductive carbon over a syringe or of inner reference solution over micropipette tips. The electrodes with charged monomers showed a more stable and sensitive response, with an average slope of -44.2 mV/decade and a detection limit of 5.8 × 10−11 mol/L (2 ng/mL). The corresponding non-imprinted sensors showed lower sensitivity, with average slopes of -24.8 mV/decade. The best sensors were successfully applied to the analysis of serum, with recoveries ranging from 96.9 to 106.1% and relative errors of 6.8%.}, keywords = {}, pubstate = {published}, tppubtype = {article} } This work shows that the synthesis of protein plastic antibodies tailored with selected charged monomers around the binding site enhances protein binding. These charged receptor sites are placed over a neutral polymeric matrix, thus inducing a suitable orientation the protein reception to its site. This is confirmed by preparing control materials with neutral monomers and also with non-imprinted template. This concept has been applied here to Prostate Specific Antigen (PSA), the protein of choice for screening prostate cancer throughout the population, with serum levels >10 ng/mL pointing out a high probability of associated cancer. Protein Imprinted Materials with charged binding sites (C/PIM) have been produced by surface imprinting over graphene layers to which the protein was first covalently attached. Vinylbenzyl(trimethylammonium chloride) and vinyl benzoate were introduced as charged monomers labelling the binding site and were allowed to self-organize around the protein. The subsequent polymerization was made by radical polymerization of vinylbenzene. Neutral PIM (N/PIM) prepared without oriented charges and non imprinted materials (NIM) obtained without template were used as controls. These materials were used to develop simple and inexpensive potentiometric sensor for PSA. They were included as ionophores in plasticized PVC membranes, and tested over electrodes of solid or liquid conductive contacts, made of conductive carbon over a syringe or of inner reference solution over micropipette tips. The electrodes with charged monomers showed a more stable and sensitive response, with an average slope of -44.2 mV/decade and a detection limit of 5.8 × 10−11 mol/L (2 ng/mL). The corresponding non-imprinted sensors showed lower sensitivity, with average slopes of -24.8 mV/decade. The best sensors were successfully applied to the analysis of serum, with recoveries ranging from 96.9 to 106.1% and relative errors of 6.8%. |
FTC Moreira, RAF Dutra, JPC Noronha, MGF Sales Novel sensory surface for creatine kinase electrochemical detection (Journal Article) Biosensors and Bioelectronics, 56 , pp. 217–222, 2014. @article{Moreira2014, title = {Novel sensory surface for creatine kinase electrochemical detection}, author = {FTC Moreira and RAF Dutra and JPC Noronha and MGF Sales }, url = {http://www.sciencedirect.com/science/article/pii/S0956566313009238}, doi = {10.1016/j.bios.2013.12.052}, year = {2014}, date = {2014-06-15}, journal = {Biosensors and Bioelectronics}, volume = {56}, pages = {217–222}, abstract = {This work describes a novel concept of biosensor for quantifying enzymes, where the substrate is immobilized directly over the working area of a screen printed electrode (Au-SPE). This concept is applied here to creatine kinase isoenzyme (CK-MB), a cardiac biomarker in ischemic conditions. It acts as a phospho-transferase on creatine (Crea), requiring the presence of phosphate. So, the phosphorylated form of creatine (Pcrea) was immobilized on the Au/SPE previously aminated with cysteamine (Cys) by self-assembling monolayer technique. Electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) studies were used to follow the chemical modifications in the Au-SPE. Since Pcrea is an electroactive species at low potential, its consumption over the platform by the enzyme changed the electrical response of the biosensor. So, CK-MB determination has been achieved in mediator free-conditions due the redox proprieties of the Pcrea. The analytical features of the resulting biosensor were studied by square wave voltammetry (SWV). The limit of detection was 0.11 µg/mL and the slope was −0.029(±0.0035) µA×mL/µg. The interference effect of troponin T (TnT), bovine serum albumin (BSA) and myoglobin (Myo) in the performance of the sensor was tested and good selectivity was observed. The biosensor was successfully applied to biological fluids, showing good stability at room temperature and excellent sensitivity and selectivity. This new concept of biosensor is especially useful for point of care (POC) applications, due to the low cost and small size of the final device.}, keywords = {}, pubstate = {published}, tppubtype = {article} } This work describes a novel concept of biosensor for quantifying enzymes, where the substrate is immobilized directly over the working area of a screen printed electrode (Au-SPE). This concept is applied here to creatine kinase isoenzyme (CK-MB), a cardiac biomarker in ischemic conditions. It acts as a phospho-transferase on creatine (Crea), requiring the presence of phosphate. So, the phosphorylated form of creatine (Pcrea) was immobilized on the Au/SPE previously aminated with cysteamine (Cys) by self-assembling monolayer technique. Electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) studies were used to follow the chemical modifications in the Au-SPE. Since Pcrea is an electroactive species at low potential, its consumption over the platform by the enzyme changed the electrical response of the biosensor. So, CK-MB determination has been achieved in mediator free-conditions due the redox proprieties of the Pcrea. The analytical features of the resulting biosensor were studied by square wave voltammetry (SWV). The limit of detection was 0.11 µg/mL and the slope was −0.029(±0.0035) µA×mL/µg. The interference effect of troponin T (TnT), bovine serum albumin (BSA) and myoglobin (Myo) in the performance of the sensor was tested and good selectivity was observed. The biosensor was successfully applied to biological fluids, showing good stability at room temperature and excellent sensitivity and selectivity. This new concept of biosensor is especially useful for point of care (POC) applications, due to the low cost and small size of the final device. |
FTC Moreira, S Sharma, RAF Dutra, JPC Noronha, AEG Cass, MGF Sales Protein-responsive polymers for point-of-care detection of cardiac biomarker (Journal Article) Sensors and Actuators B: Chemical, 196 , pp. 123–132, 2014. @article{Moreira2014b, title = {Protein-responsive polymers for point-of-care detection of cardiac biomarker}, author = {FTC Moreira and S Sharma and RAF Dutra and JPC Noronha and AEG Cass and MGF Sales}, url = {http://www.sciencedirect.com/science/article/pii/S0925400514000550}, doi = {10.1016/j.snb.2014.01.038}, year = {2014}, date = {2014-06-01}, journal = {Sensors and Actuators B: Chemical}, volume = {196}, pages = {123–132}, abstract = {This work describes a novel use for the polymeric film, poly(o-aminophenol) (PAP) that was made responsive to a specific protein. This was achieved through templated electropolymerization of aminophenol (AP) in the presence of protein. The procedure involved adsorbing protein on the electrode surface and thereafter electroploymerizing the aminophenol. Proteins embedded at the outer surface of the polymeric film were digested by proteinase K and then washed away thereby creating vacant sites. The capacity of the template film to specifically rebind protein was tested with myoglobin (Myo), a cardiac biomarker for ischemia. The films acted as biomimetic artificial antibodies and were produced on a gold (Au) screen printed electrode (SPE), as a step towards disposable sensors to enable point-of-care applications. Raman spectroscopy was used to follow the surface modification of the Au-SPE. The ability of the material to rebind Myo was measured by electrochemical techniques, namely electrochemical impedance spectroscopy (EIS) and square wave voltammetry (SWV). The devices displayed linear responses to Myo in EIS and SWV assays down to 4.0 and 3.5 μg/mL, respectively, with detection limits of 1.5 and 0.8 μg/mL. Good selectivity was observed in the presence of troponin T (TnT) and creatine kinase (CKMB) in SWV assays, and accurate results were obtained in applications to spiked serum. The sensor described in this work is a potential tool for screening Myo in point-of-care due to the simplicity of fabrication, disposability, short time response, low cost, good sensitivity and selectivity.}, keywords = {}, pubstate = {published}, tppubtype = {article} } This work describes a novel use for the polymeric film, poly(o-aminophenol) (PAP) that was made responsive to a specific protein. This was achieved through templated electropolymerization of aminophenol (AP) in the presence of protein. The procedure involved adsorbing protein on the electrode surface and thereafter electroploymerizing the aminophenol. Proteins embedded at the outer surface of the polymeric film were digested by proteinase K and then washed away thereby creating vacant sites. The capacity of the template film to specifically rebind protein was tested with myoglobin (Myo), a cardiac biomarker for ischemia. The films acted as biomimetic artificial antibodies and were produced on a gold (Au) screen printed electrode (SPE), as a step towards disposable sensors to enable point-of-care applications. Raman spectroscopy was used to follow the surface modification of the Au-SPE. The ability of the material to rebind Myo was measured by electrochemical techniques, namely electrochemical impedance spectroscopy (EIS) and square wave voltammetry (SWV). The devices displayed linear responses to Myo in EIS and SWV assays down to 4.0 and 3.5 μg/mL, respectively, with detection limits of 1.5 and 0.8 μg/mL. Good selectivity was observed in the presence of troponin T (TnT) and creatine kinase (CKMB) in SWV assays, and accurate results were obtained in applications to spiked serum. The sensor described in this work is a potential tool for screening Myo in point-of-care due to the simplicity of fabrication, disposability, short time response, low cost, good sensitivity and selectivity. |
NS Ferreira, MGF Sales Biosensors and Bioelectronics, 53 , pp. 193–199, 2014. @article{Ferreira2014, title = {Disposable immunosensor using a simple method for oriented antibody immobilization for label-free real-time detection of an oxidative stress biomarker implicated in cancer diseases}, author = {NS Ferreira and MGF Sales}, url = {http://www.sciencedirect.com/science/article/pii/S095656631300674X}, doi = {10.1016/j.bios.2013.09.056}, year = {2014}, date = {2014-03-15}, journal = {Biosensors and Bioelectronics}, volume = {53}, pages = {193–199}, abstract = {This work proposes a novel approach for a suitable orientation of antibodies (Ab) on an immunosensing platform, applied here to the determination of 8-hydroxy-2′-deoxyguanosine (8OHdG), a biomarker of oxidative stress that has been associated to chronic diseases, such as cancer. The anti-8OHdG was bound to an amine modified gold support through its Fc region after activation of its carboxylic functions. Non-oriented approaches of Ab binding to the platform were tested in parallel, in order to show that the presented methodology favored Ab/Ag affinity and immunodetection of the antigen. The immunosensor design was evaluated by quartz-crystal microbalance with dissipation, atomic force microscopy, electrochemical impedance spectroscopy (EIS) and square-wave voltammetry. EIS was also a suitable technique to follow the analytical behavior of the device against 8OHdG. The affinity binding between 8OHdG and the antibody immobilized in the gold modified platform increased the charge transfer resistance across the electrochemical set-up. The observed behavior was linear from 0.02 to 7.0 ng/mL of 8OHdG concentrations. The interference from glucose, urea and creatinine was found negligible. An attempt of application to synthetic samples was also successfully conducted. Overall, the presented approach enabled the production of suitably oriented Abs over a gold platform by means of a much simpler process than other oriented-Ab binding approaches described in the literature, as far as we know, and was successful in terms of analytical features and sample application.}, keywords = {}, pubstate = {published}, tppubtype = {article} } This work proposes a novel approach for a suitable orientation of antibodies (Ab) on an immunosensing platform, applied here to the determination of 8-hydroxy-2′-deoxyguanosine (8OHdG), a biomarker of oxidative stress that has been associated to chronic diseases, such as cancer. The anti-8OHdG was bound to an amine modified gold support through its Fc region after activation of its carboxylic functions. Non-oriented approaches of Ab binding to the platform were tested in parallel, in order to show that the presented methodology favored Ab/Ag affinity and immunodetection of the antigen. The immunosensor design was evaluated by quartz-crystal microbalance with dissipation, atomic force microscopy, electrochemical impedance spectroscopy (EIS) and square-wave voltammetry. EIS was also a suitable technique to follow the analytical behavior of the device against 8OHdG. The affinity binding between 8OHdG and the antibody immobilized in the gold modified platform increased the charge transfer resistance across the electrochemical set-up. The observed behavior was linear from 0.02 to 7.0 ng/mL of 8OHdG concentrations. The interference from glucose, urea and creatinine was found negligible. An attempt of application to synthetic samples was also successfully conducted. Overall, the presented approach enabled the production of suitably oriented Abs over a gold platform by means of a much simpler process than other oriented-Ab binding approaches described in the literature, as far as we know, and was successful in terms of analytical features and sample application. |
G Cabral-Miranda, M Gidlund, MGF Sales Backside-surface imprint as a new strategy to generate specific plastic antibody materials (Journal Article) Journal of Materials Chemistry B, 2 (20), pp. 3087-3095, 2014. @article{Cabral-Miranda2014b, title = {Backside-surface imprint as a new strategy to generate specific plastic antibody materials}, author = {G Cabral-Miranda and M Gidlund and MGF Sales }, url = {http://pubs.rsc.org/EN/content/articlelanding/2014/tb/c3tb21740j#!divAbstract http://recipp.ipp.pt/handle/10400.22/6725}, doi = {10.1039/C3TB21740J}, year = {2014}, date = {2014-03-05}, journal = {Journal of Materials Chemistry B}, volume = {2}, number = {20}, pages = {3087-3095}, abstract = {A backside protein-surface imprinting process is presented herein as a novel way to generate specific synthetic antibody materials. The template is covalently bonded to a carboxylated-PVC supporting film previously cast on gold, let to interact with charged monomers and surrounded next by another thick polymer. This polymer is then covalently attached to a transducing element and the backside of this structure (supporting film plus template) is removed as a regular “tape”. The new sensing layer is exposed after the full template removal, showing a high density of re-binding positions, as evidenced by SEM. To ensure that the templates have been efficiently removed, this re-binding layer was cleaned further with a proteolytic enzyme and solution washout. The final material was named MAPS, as in the back-side reading of SPAM, because it acts as a back-side imprinting of this recent approach. It was able to generate, for the first time, a specific response to a complex biomolecule from a synthetic material. Non-imprinted materials (NIMs) were also produced as blank and were used as a control of the imprinting process. All chemical modifications were followed by electrochemical techniques. This was done on a supporting film and transducing element of both MAPS and NIM. Only the MAPS-based device responded to oxLDL and the sensing layer was insensitive to other serum proteins, such as myoglobin and haemoglobin. Linear behaviour between log(C, μg mL−1) versus charged tranfer resistance (RCT, Ω) was observed by electrochemical impedance spectroscopy (EIS). Calibrations made in Fetal Calf Serum (FCS) were linear from 2.5 to 12.5 μg mL−1 (RCT = 946.12 × log C + 1590.7) with an R-squared of 0.9966. Overall, these were promising results towards the design of materials acting close to the natural antibodies and applied to practical use of clinical interest.}, keywords = {}, pubstate = {published}, tppubtype = {article} } A backside protein-surface imprinting process is presented herein as a novel way to generate specific synthetic antibody materials. The template is covalently bonded to a carboxylated-PVC supporting film previously cast on gold, let to interact with charged monomers and surrounded next by another thick polymer. This polymer is then covalently attached to a transducing element and the backside of this structure (supporting film plus template) is removed as a regular “tape”. The new sensing layer is exposed after the full template removal, showing a high density of re-binding positions, as evidenced by SEM. To ensure that the templates have been efficiently removed, this re-binding layer was cleaned further with a proteolytic enzyme and solution washout. The final material was named MAPS, as in the back-side reading of SPAM, because it acts as a back-side imprinting of this recent approach. It was able to generate, for the first time, a specific response to a complex biomolecule from a synthetic material. Non-imprinted materials (NIMs) were also produced as blank and were used as a control of the imprinting process. All chemical modifications were followed by electrochemical techniques. This was done on a supporting film and transducing element of both MAPS and NIM. Only the MAPS-based device responded to oxLDL and the sensing layer was insensitive to other serum proteins, such as myoglobin and haemoglobin. Linear behaviour between log(C, μg mL−1) versus charged tranfer resistance (RCT, Ω) was observed by electrochemical impedance spectroscopy (EIS). Calibrations made in Fetal Calf Serum (FCS) were linear from 2.5 to 12.5 μg mL−1 (RCT = 946.12 × log C + 1590.7) with an R-squared of 0.9966. Overall, these were promising results towards the design of materials acting close to the natural antibodies and applied to practical use of clinical interest. |
S Teixeira, RS Conlan, OJ Guy, MGF Sales Label-free human chorionic gonadotropin detection at picogram levels using oriented antibodies bound to graphene screen printed electrodes (Journal Article) Journal of Materials Chemistry B, 2 (13), pp. 1852-1865, 2014. @article{Teixeira2014, title = {Label-free human chorionic gonadotropin detection at picogram levels using oriented antibodies bound to graphene screen printed electrodes }, author = {S Teixeira and RS Conlan and OJ Guy and MGF Sales}, url = {http://pubs.rsc.org/EN/content/articlelanding/2014/tb/c3tb21235a#!divAbstract http://recipp.ipp.pt/handle/10400.22/6726}, doi = {10.1039/C3TB21235A}, year = {2014}, date = {2014-01-10}, journal = {Journal of Materials Chemistry B}, volume = {2}, number = {13}, pages = {1852-1865}, abstract = {Human chorionic gonadotropin (hCG) is a key diagnostic marker of pregnancy and an important biomarker for cancers in the prostate, ovaries and bladder and therefore of great importance in diagnosis. For this purpose, a new immunosensor of screen-printed electrodes (SPEs) is presented here. The device was fabricated by introducing a polyaniline (PANI) conductive layer, via in situ electropolymerization of aniline, onto a screen-printed graphene support. The PANI-coated graphene acts as the working electrode of a three terminal electrochemical sensor. The working electrode is functionalised with anti-hCG, by means of a simple process that enabled oriented antibody binding to the PANI layer. The antibody was attached to PANI following activation of the –COOH group at the Fc terminal. Functionalisation of the electrode was analysed and optimized using Electrochemical Impedance Spectroscopy (EIS). Chemical modification of the surface was characterised using Fourier transform infrared, and Raman spectroscopy with confocal microscopy. The graphene–SPE–PANI devices displayed linear responses to hCG in EIS assays from 0.001 to 50 ng mL−1 in real urine, with a detection limit of 0.286 pg mL−1. High selectivity was observed with respect to the presence of the constituent components of urine (urea, creatinine, magnesium chloride, calcium chloride, sodium dihydrogen phosphate, ammonium chloride, potassium sulphate and sodium chloride) at their normal levels, with a negligible sensor response to these chemicals. Successful detection of hCG was also achieved in spiked samples of real urine from a pregnant woman. The immunosensor developed is a promising tool for point-of-care detection of hCG, due to its excellent detection capability, simplicity of fabrication, low-cost, high sensitivity and selectivity.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Human chorionic gonadotropin (hCG) is a key diagnostic marker of pregnancy and an important biomarker for cancers in the prostate, ovaries and bladder and therefore of great importance in diagnosis. For this purpose, a new immunosensor of screen-printed electrodes (SPEs) is presented here. The device was fabricated by introducing a polyaniline (PANI) conductive layer, via in situ electropolymerization of aniline, onto a screen-printed graphene support. The PANI-coated graphene acts as the working electrode of a three terminal electrochemical sensor. The working electrode is functionalised with anti-hCG, by means of a simple process that enabled oriented antibody binding to the PANI layer. The antibody was attached to PANI following activation of the –COOH group at the Fc terminal. Functionalisation of the electrode was analysed and optimized using Electrochemical Impedance Spectroscopy (EIS). Chemical modification of the surface was characterised using Fourier transform infrared, and Raman spectroscopy with confocal microscopy. The graphene–SPE–PANI devices displayed linear responses to hCG in EIS assays from 0.001 to 50 ng mL−1 in real urine, with a detection limit of 0.286 pg mL−1. High selectivity was observed with respect to the presence of the constituent components of urine (urea, creatinine, magnesium chloride, calcium chloride, sodium dihydrogen phosphate, ammonium chloride, potassium sulphate and sodium chloride) at their normal levels, with a negligible sensor response to these chemicals. Successful detection of hCG was also achieved in spiked samples of real urine from a pregnant woman. The immunosensor developed is a promising tool for point-of-care detection of hCG, due to its excellent detection capability, simplicity of fabrication, low-cost, high sensitivity and selectivity. |
G Cabral-Miranda, EHG Yamashiro-Kanashiro, M Gidlund, MGF Sales Specific label-free and real-time detection of oxidized low density lipoprotein (oxLDL) using an immunosensor with three monoclonal antibodies (Journal Article) Journal of Materials Chemistry B, 2 (5), pp. 477-484, 2014. @article{Cabral-Miranda2014, title = {Specific label-free and real-time detection of oxidized low density lipoprotein (oxLDL) using an immunosensor with three monoclonal antibodies}, author = {G Cabral-Miranda and EHG Yamashiro-Kanashiro and M Gidlund and MGF Sales}, url = {http://pubs.rsc.org/EN/content/articlelanding/2013/tb/c3tb21048k#!divAbstract http://recipp.ipp.pt/handle/10400.22/6727}, doi = {10.1039/C3TB21048K}, year = {2014}, date = {2014-01-02}, journal = {Journal of Materials Chemistry B}, volume = {2}, number = {5}, pages = {477-484}, abstract = {Increased levels of plasma oxLDL, which is the oxidized fraction of Low Density Lipoprotein (LDL), are associated with atherosclerosis, an inflammatory disease, and the subsequent development of severe cardiovascular diseases that are today a major cause of death in modern countries. It is therefore important to find a reliable and fast assay to determine oxLDL in serum. A new immunosensor employing three monoclonal antibodies (mAbs) against oxLDL is proposed in this work as a quick and effective way to monitor oxLDL. The oxLDL was first employed to produce anti-oxLDL monoclonal antibodies by hybridoma cells that were previously obtained. The immunosensor was set-up by self-assembling cysteamine (Cyst) on a gold (Au) layer (4 mm diameter) of a disposable screen-printed electrode. Three mAbs were allowed to react with N-hydroxysuccinimide (NHS) and ethyl(dimethylaminopropyl)carbodiimide (EDAC), and subsequently incubated in the Au/Cys. Albumin from bovine serum (BSA) was immobilized further to ensure that other molecules apart from oxLDL could not bind to the electrode surface. All steps were followed by various characterization techniques such as electrochemical impedance spectroscopy (EIS) and square wave voltammetry (SWV). The analytical operation of the immunosensor was obtained by incubating the sensing layer of the device in oxLDL for 15 minutes, prior to EIS and SWV. This was done by using standard oxLDL solutions prepared in foetal calf serum, in order to simulate patient's plasma with circulating oxLDL. A sensitive response was observed from 0.5 to 18.0 μg mL−1. The device was successfully applied to determine the oxLDL fraction in real serum, without prior dilution or necessary chemical treatment. The use of multiple monoclonal antibodies on a biosensing platform seemed to be a successful approach to produce a specific response towards a complex multi-analyte target, correlating well with the level of oxLDL within atherosclerosis disease, in a simple, fast and cheap way.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Increased levels of plasma oxLDL, which is the oxidized fraction of Low Density Lipoprotein (LDL), are associated with atherosclerosis, an inflammatory disease, and the subsequent development of severe cardiovascular diseases that are today a major cause of death in modern countries. It is therefore important to find a reliable and fast assay to determine oxLDL in serum. A new immunosensor employing three monoclonal antibodies (mAbs) against oxLDL is proposed in this work as a quick and effective way to monitor oxLDL. The oxLDL was first employed to produce anti-oxLDL monoclonal antibodies by hybridoma cells that were previously obtained. The immunosensor was set-up by self-assembling cysteamine (Cyst) on a gold (Au) layer (4 mm diameter) of a disposable screen-printed electrode. Three mAbs were allowed to react with N-hydroxysuccinimide (NHS) and ethyl(dimethylaminopropyl)carbodiimide (EDAC), and subsequently incubated in the Au/Cys. Albumin from bovine serum (BSA) was immobilized further to ensure that other molecules apart from oxLDL could not bind to the electrode surface. All steps were followed by various characterization techniques such as electrochemical impedance spectroscopy (EIS) and square wave voltammetry (SWV). The analytical operation of the immunosensor was obtained by incubating the sensing layer of the device in oxLDL for 15 minutes, prior to EIS and SWV. This was done by using standard oxLDL solutions prepared in foetal calf serum, in order to simulate patient's plasma with circulating oxLDL. A sensitive response was observed from 0.5 to 18.0 μg mL−1. The device was successfully applied to determine the oxLDL fraction in real serum, without prior dilution or necessary chemical treatment. The use of multiple monoclonal antibodies on a biosensing platform seemed to be a successful approach to produce a specific response towards a complex multi-analyte target, correlating well with the level of oxLDL within atherosclerosis disease, in a simple, fast and cheap way. |
2013
RB Queirós, A Guedes, PVS Marques, JPC Noronha, MGF Sales Sensors and Actuators B: Chemical, 189 , pp. 21-29, 2013. @article{RB2013, title = {Recycling old screen-printed electrodes with newly designed plastic antibodies on the wall of carbon nanotubes as sensory element for in situ detection of bacterial toxins in water}, author = {RB Queirós and A Guedes and PVS Marques and JPC Noronha and MGF Sales }, url = {http://www.sciencedirect.com/science/article/pii/S0925400512013081 http://recipp.ipp.pt/handle/10400.22/6742}, doi = {10.1016/j.snb.2012.11.112}, year = {2013}, date = {2013-12-01}, journal = {Sensors and Actuators B: Chemical}, volume = {189}, pages = {21-29}, abstract = {Using low cost portable devices that enable a single analytical step for screening environmental contaminants is today a demanding issue. This concept is here tried out by recycling screen-printed electrodes that were to be disposed of and by choosing as sensory element a low cost material offering specific response for an environmental contaminant. Microcystins (MCs) were used as target analyte, for being dangerous toxins produced by cyanobacteria released into water bodies. The sensory element was a plastic antibody designed by surface imprinting with carefully selected monomers to ensure a specific response. These were designed on the wall of carbon nanotubes, taking advantage of their exceptional electrical properties. The stereochemical ability of the sensory material to detect MCs was checked by preparing blank materials where the imprinting stage was made without the template molecule. The novel sensory material for MCs was introduced in a polymeric matrix and evaluated against potentiometric measurements. Nernstian response was observed from 7.24 × 10−10 to 1.28 × 10−9 M in buffer solution (10 mM HEPES, 150 mM NaCl, pH 6.6), with average slopes of −62 mVdecade−1 and detection capabilities below 1 nM. The blank materials were unable to provide a linear response against log(concentration), showing only a slight potential change towards more positive potentials with increasing concentrations (while that ofthe plastic antibodies moved to more negative values), with a maximum rate of +33 mVdecade−1. The sensors presented good selectivity towards sulphate, iron and ammonium ions, and also chloroform and tetrachloroethylene (TCE) and fast response (<20 s). This concept was successfully tested on the analysis of spiked environmental water samples. The sensors were further applied onto recycled chips, comprehending one site for the reference electrode and two sites for different selective membranes, in a biparametric approach for “in situ” analysis.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Using low cost portable devices that enable a single analytical step for screening environmental contaminants is today a demanding issue. This concept is here tried out by recycling screen-printed electrodes that were to be disposed of and by choosing as sensory element a low cost material offering specific response for an environmental contaminant. Microcystins (MCs) were used as target analyte, for being dangerous toxins produced by cyanobacteria released into water bodies. The sensory element was a plastic antibody designed by surface imprinting with carefully selected monomers to ensure a specific response. These were designed on the wall of carbon nanotubes, taking advantage of their exceptional electrical properties. The stereochemical ability of the sensory material to detect MCs was checked by preparing blank materials where the imprinting stage was made without the template molecule. The novel sensory material for MCs was introduced in a polymeric matrix and evaluated against potentiometric measurements. Nernstian response was observed from 7.24 × 10−10 to 1.28 × 10−9 M in buffer solution (10 mM HEPES, 150 mM NaCl, pH 6.6), with average slopes of −62 mVdecade−1 and detection capabilities below 1 nM. The blank materials were unable to provide a linear response against log(concentration), showing only a slight potential change towards more positive potentials with increasing concentrations (while that ofthe plastic antibodies moved to more negative values), with a maximum rate of +33 mVdecade−1. The sensors presented good selectivity towards sulphate, iron and ammonium ions, and also chloroform and tetrachloroethylene (TCE) and fast response (<20 s). This concept was successfully tested on the analysis of spiked environmental water samples. The sensors were further applied onto recycled chips, comprehending one site for the reference electrode and two sites for different selective membranes, in a biparametric approach for “in situ” analysis. |
SAA Almeida, MCBSM Montenegro, MGF Sales New and low cost plastic membrane electrode with low detection limits for sulfadimethoxine determination in aquaculture waters (Journal Article) Journal of Electroanalytical Chemistry, 709 , pp. 39–45, 2013. @article{Almeida2013, title = {New and low cost plastic membrane electrode with low detection limits for sulfadimethoxine determination in aquaculture waters}, author = {SAA Almeida and MCBSM Montenegro and MGF Sales}, url = {http://www.sciencedirect.com/science/article/pii/S1572665713004360 http://recipp.ipp.pt/handle/10400.22/6728}, doi = {10.1016/j.jelechem.2013.09.029}, year = {2013}, date = {2013-11-15}, journal = {Journal of Electroanalytical Chemistry}, volume = {709}, pages = {39–45}, abstract = {Sulfadimethoxine (SDM) is one of the drugs, often used in the aquaculture sector to prevent the spread of disease in freshwater fish aquaculture. Its spread through the soil and surface water can contribute to an increase in bacterial resistance. It is therefore important to control this product in the environment. This work proposes a simple and low-cost potentiometric device to monitor the levels of SDM in aquaculture waters, thus avoiding its unnecessary release throughout the environment. The device combines a micropipette tip with a PVC membrane selective to SDM, prepared from an appropriate cocktail, and an inner reference solution. The membrane includes 1% of a porphyrin derivative acting as ionophore and a small amount of a lipophilic cationic additive (corresponding to 0.2% in molar ratio). The composition of the inner solution was optimized with regard to the kind and/or concentration of primary ion, chelating agent and/or a specific interfering charged species, in different concentration ranges. Electrodes constructed with inner reference solutions of 1 × 10−8 mol/L SDM and 1 × 10−4 mol/L chromate ion showed the best analytical features. Near-Nernstian response was obtained with slopes of −54.1 mV/decade, an extraordinary detection limit of 7.5 ng/mL (2.4 × 10−8 mol/L) when compared with other electrodes of the same type. The reproducibility, stability and response time are good and even better than those obtained by liquid contact ISEs. Recovery values of 98.9% were obtained from the analysis of aquaculture water samples.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Sulfadimethoxine (SDM) is one of the drugs, often used in the aquaculture sector to prevent the spread of disease in freshwater fish aquaculture. Its spread through the soil and surface water can contribute to an increase in bacterial resistance. It is therefore important to control this product in the environment. This work proposes a simple and low-cost potentiometric device to monitor the levels of SDM in aquaculture waters, thus avoiding its unnecessary release throughout the environment. The device combines a micropipette tip with a PVC membrane selective to SDM, prepared from an appropriate cocktail, and an inner reference solution. The membrane includes 1% of a porphyrin derivative acting as ionophore and a small amount of a lipophilic cationic additive (corresponding to 0.2% in molar ratio). The composition of the inner solution was optimized with regard to the kind and/or concentration of primary ion, chelating agent and/or a specific interfering charged species, in different concentration ranges. Electrodes constructed with inner reference solutions of 1 × 10−8 mol/L SDM and 1 × 10−4 mol/L chromate ion showed the best analytical features. Near-Nernstian response was obtained with slopes of −54.1 mV/decade, an extraordinary detection limit of 7.5 ng/mL (2.4 × 10−8 mol/L) when compared with other electrodes of the same type. The reproducibility, stability and response time are good and even better than those obtained by liquid contact ISEs. Recovery values of 98.9% were obtained from the analysis of aquaculture water samples. |
APM Tavares, FTC Moreira, MGF Sales RSC Advances, 3 (48), pp. 26210-26219, 2013. @article{Tavares2013, title = {Haemoglobin smart plastic antibody material tailored with charged binding sites on silica nanoparticles: its application as an ionophore in potentiometric transduction}, author = {APM Tavares and FTC Moreira and MGF Sales}, url = {http://pubs.rsc.org/en/content/articlelanding/2013/ra/c3ra44766a#!divAbstract http://recipp.ipp.pt/handle/10400.22/6704}, doi = {10.1039/C3RA44766A}, year = {2013}, date = {2013-10-16}, journal = {RSC Advances}, volume = {3}, number = {48}, pages = {26210-26219}, abstract = {This work uses surface imprinting to design a novel smart plastic antibody material (SPAM) for Haemoglobin (Hb). Charged binding sites are described here for the first time to tailor plastic antibody nanostructures for a large size protein such as Hb. Its application to design small, portable and low cost potentiometric devices is presented. The SPAM material was obtained by linking Hb to silica nanoparticles and allowing its ionic interaction with charged vinyl monomers. A neutral polymeric matrix was created around these and the imprinted protein removed. Additional materials were designed in parallel acting as a control: a neutral imprinted material (NSPAM), obtained by removing the charged monomers from the procedure, and the Non-Imprinted (NI) versions of SPAM and NSPAM by removing the template. SEM analysis confirmed the surface modification of the silica nanoparticles. All materials were mixed with PVC/plasticizer and applied as selective membranes in potentiometric transduction. Electromotive force (emf) variations were detected only for selective membranes having a lipophilic anionic additive in the membrane. The presence of Hb inside these membranes was evident and confirmed by FTIR, optical microscopy and Raman spectroscopy. The best performance was found for SPAM-based selective membranes with an anionic lipophilic additive, at pH 5. The limits of detection were 43.8 μg mL−1 and linear responses were obtained down to 83.8 μg mL−1, with an average cationic slope of +40 mV per decade. Good selectivity was also observed against other coexisting biomolecules. The analytical application was conducted successfully, showing accurate and precise results.}, keywords = {}, pubstate = {published}, tppubtype = {article} } This work uses surface imprinting to design a novel smart plastic antibody material (SPAM) for Haemoglobin (Hb). Charged binding sites are described here for the first time to tailor plastic antibody nanostructures for a large size protein such as Hb. Its application to design small, portable and low cost potentiometric devices is presented. The SPAM material was obtained by linking Hb to silica nanoparticles and allowing its ionic interaction with charged vinyl monomers. A neutral polymeric matrix was created around these and the imprinted protein removed. Additional materials were designed in parallel acting as a control: a neutral imprinted material (NSPAM), obtained by removing the charged monomers from the procedure, and the Non-Imprinted (NI) versions of SPAM and NSPAM by removing the template. SEM analysis confirmed the surface modification of the silica nanoparticles. All materials were mixed with PVC/plasticizer and applied as selective membranes in potentiometric transduction. Electromotive force (emf) variations were detected only for selective membranes having a lipophilic anionic additive in the membrane. The presence of Hb inside these membranes was evident and confirmed by FTIR, optical microscopy and Raman spectroscopy. The best performance was found for SPAM-based selective membranes with an anionic lipophilic additive, at pH 5. The limits of detection were 43.8 μg mL−1 and linear responses were obtained down to 83.8 μg mL−1, with an average cationic slope of +40 mV per decade. Good selectivity was also observed against other coexisting biomolecules. The analytical application was conducted successfully, showing accurate and precise results. |
FTC Moreira, RAF Dutra, JPC Noronha, MGF Sales Electrochemical biosensor based on biomimetic material for myoglobin detection (Journal Article) Elsevier, 107 , pp. 481–487, 2013. @article{Moreira2013b, title = {Electrochemical biosensor based on biomimetic material for myoglobin detection}, author = {FTC Moreira and RAF Dutra and JPC Noronha and MGF Sales}, url = {http://www.sciencedirect.com/science/article/pii/S0013468613011675 http://recipp.ipp.pt/handle/10400.22/6729}, doi = {10.1016/j.electacta.2013.06.061}, year = {2013}, date = {2013-09-30}, journal = {Elsevier}, volume = {107}, pages = {481–487}, abstract = {A novel reusable molecularly imprinted polymer (MIP) assembled on a polymeric layer of carboxylated poly(vinyl chloride) (PVCsingle bondCOOH) for myoglobin (Myo) detection was developed. This polymer was casted on the gold working area of a screen printed electrode (Au-SPE), creating a novel disposable device relying on plastic antibodies. Electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) and Fourier transform infrared spectroscopy (FTIR) studies confirmed the surface modification. The MIP/Au-SPE devices displayed a linear behaviour in EIS from 0.852 to 4.26 μg mL−1, of positive slope 6.50 ± 1.48 (kΩ mL μg−1). The limit of detection was 2.25 μg mL−1. Square wave voltammetric (SWV) assays were made in parallel and showed linear responses between 1.1 and 2.98 μg mL−1. A current decrease was observed against Myo concentration, producing average slopes of −0.28 ± 0.038 μA mL μg−1. MIP/Au-SPE also showed good results in terms of selectivity. The error% found for each interfering species were 7% for troponin T (TnT), 11% for bovine serum albumin (BSA) and 2% for creatine kinase MB (CKMB), respectively. Overall, the technical modification over the Au-SPE was found a suitable approach for screening Myo in biological fluids.}, keywords = {}, pubstate = {published}, tppubtype = {article} } A novel reusable molecularly imprinted polymer (MIP) assembled on a polymeric layer of carboxylated poly(vinyl chloride) (PVCsingle bondCOOH) for myoglobin (Myo) detection was developed. This polymer was casted on the gold working area of a screen printed electrode (Au-SPE), creating a novel disposable device relying on plastic antibodies. Electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) and Fourier transform infrared spectroscopy (FTIR) studies confirmed the surface modification. The MIP/Au-SPE devices displayed a linear behaviour in EIS from 0.852 to 4.26 μg mL−1, of positive slope 6.50 ± 1.48 (kΩ mL μg−1). The limit of detection was 2.25 μg mL−1. Square wave voltammetric (SWV) assays were made in parallel and showed linear responses between 1.1 and 2.98 μg mL−1. A current decrease was observed against Myo concentration, producing average slopes of −0.28 ± 0.038 μA mL μg−1. MIP/Au-SPE also showed good results in terms of selectivity. The error% found for each interfering species were 7% for troponin T (TnT), 11% for bovine serum albumin (BSA) and 2% for creatine kinase MB (CKMB), respectively. Overall, the technical modification over the Au-SPE was found a suitable approach for screening Myo in biological fluids. |
FTC Moreira, S Sharma, RAF Dutra, JPC Noronha, AEG Cass, MGF Sales Smart Plastic Antibody Material (SPAM) tailored on disposable screen printed electrodes for protein recognition: application to Myoglobin detection (Journal Article) Biosensors and Bioelectronics, 45 , pp. 237–244, 2013. @article{Moreira2013b, title = {Smart Plastic Antibody Material (SPAM) tailored on disposable screen printed electrodes for protein recognition: application to Myoglobin detection}, author = {FTC Moreira and S Sharma and RAF Dutra and JPC Noronha and AEG Cass and MGF Sales}, url = {http://www.sciencedirect.com/science/article/pii/S0956566313001103 http://recipp.ipp.pt/handle/10400.22/6732}, doi = {10.1016/j.bios.2013.02.012}, year = {2013}, date = {2013-07-15}, journal = {Biosensors and Bioelectronics}, volume = {45}, pages = {237–244}, abstract = {This work introduces two major changes to the conventional protocol for designing plastic antibodies: (i) the imprinted sites were created with charged monomers while the surrounding environment was tailored using neutral material; and (ii) the protein was removed from its imprinted site by means of a protease, aiming at preserving the polymeric network of the plastic antibody. To our knowledge, these approaches were never presented before and the resulting material was named here as smart plastic antibody material (SPAM). As proof of concept, SPAM was tailored on top of disposable gold-screen printed electrodes (Au-SPE), following a bottom-up approach, for targeting myoglobin (Myo) in a point-of-care context. The existence of imprinted sites was checked by comparing a SPAM modified surface to a negative control, consisting of similar material where the template was omitted from the procedure and called non-imprinted materials (NIMs). All stages of the creation of the SPAM and NIM on the Au layer were followed by both electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). AFM imaging was also performed to characterize the topography of the surface. There are two major reasons supporting the fact that plastic antibodies were effectively designed by the above approach: (i) they were visualized for the first time by AFM, being present only in the SPAM network; and (ii) only the SPAM material was able to rebind to the target protein and produce a linear electrical response against EIS and square wave voltammetry (SWV) assays, with NIMs showing a similar-to-random behavior. The SPAM/Au-SPE devices displayed linear responses to Myo in EIS and SWV assays down to 3.5 μg/mL and 0.58 μg/mL, respectively, with detection limits of 1.5 and 0.28 μg/mL. SPAM materials also showed negligible interference from troponin T (TnT), bovine serum albumin (BSA) and urea under SWV assays, showing promising results for point-of-care applications when applied to spiked biological fluids.}, keywords = {}, pubstate = {published}, tppubtype = {article} } This work introduces two major changes to the conventional protocol for designing plastic antibodies: (i) the imprinted sites were created with charged monomers while the surrounding environment was tailored using neutral material; and (ii) the protein was removed from its imprinted site by means of a protease, aiming at preserving the polymeric network of the plastic antibody. To our knowledge, these approaches were never presented before and the resulting material was named here as smart plastic antibody material (SPAM). As proof of concept, SPAM was tailored on top of disposable gold-screen printed electrodes (Au-SPE), following a bottom-up approach, for targeting myoglobin (Myo) in a point-of-care context. The existence of imprinted sites was checked by comparing a SPAM modified surface to a negative control, consisting of similar material where the template was omitted from the procedure and called non-imprinted materials (NIMs). All stages of the creation of the SPAM and NIM on the Au layer were followed by both electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). AFM imaging was also performed to characterize the topography of the surface. There are two major reasons supporting the fact that plastic antibodies were effectively designed by the above approach: (i) they were visualized for the first time by AFM, being present only in the SPAM network; and (ii) only the SPAM material was able to rebind to the target protein and produce a linear electrical response against EIS and square wave voltammetry (SWV) assays, with NIMs showing a similar-to-random behavior. The SPAM/Au-SPE devices displayed linear responses to Myo in EIS and SWV assays down to 3.5 μg/mL and 0.58 μg/mL, respectively, with detection limits of 1.5 and 0.28 μg/mL. SPAM materials also showed negligible interference from troponin T (TnT), bovine serum albumin (BSA) and urea under SWV assays, showing promising results for point-of-care applications when applied to spiked biological fluids. |
FTC Moreira, RAF Dutra, JPC Noronha, JCS Fernandes, MGF Sales Novel biosensing device for point-of-care applications with plastic antibodies grown on Au-Screen Printed Electrodes (Journal Article) Sensors and Actuators B: Chemical, 182 , pp. 733–740, 2013. @article{Moreira2013b, title = {Novel biosensing device for point-of-care applications with plastic antibodies grown on Au-Screen Printed Electrodes}, author = {FTC Moreira and RAF Dutra and JPC Noronha and JCS Fernandes and MGF Sales}, url = {http://www.sciencedirect.com/science/article/pii/S0925400513003882 http://recipp.ipp.pt/handle/10400.22/6731}, doi = {10.1016/j.snb.2013.03.099}, year = {2013}, date = {2013-06-01}, journal = {Sensors and Actuators B: Chemical}, volume = {182}, pages = {733–740}, abstract = {A gold screen printed electrode (Au-SPE) was modified by merging Molecular Imprinting and Self-Assembly Monolayer techniques for fast screening cardiac biomarkers in point-of-care (POC). For this purpose, Myoglobin (Myo) was selected as target analyte and its plastic antibody imprinted over a glutaraldehyde (Glu)/cysteamine (Cys) layer on the gold-surface. The imprinting effect was produced by growing a reticulated polymer of acrylamide (AAM) and N,N′-methylenebisacrylamide (NNMBA) around the Myo template, covalently attached to the biosensing surface. Electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) studies were carried out in all chemical modification steps to confirm the surface changes in the Au-SPE. The analytical features of the resulting biosensor were studied by different electrochemical techniques, including EIS, square wave voltammetry (SWV) and potentiometry. The limits of detection ranged from 0.13 to 8 μg/mL. Only potentiometry assays showed limits of detection including the cut-off Myo levels. Quantitative information was also produced for Myo concentrations ≥0.2 μg/mL. The linear response of the biosensing device showed an anionic slope of ~70 mV per decade molar concentration up to 0.3 μg/mL. The interference of coexisting species was tested and good selectivity was observed. The biosensor was successfully applied to biological fluids.}, keywords = {}, pubstate = {published}, tppubtype = {article} } A gold screen printed electrode (Au-SPE) was modified by merging Molecular Imprinting and Self-Assembly Monolayer techniques for fast screening cardiac biomarkers in point-of-care (POC). For this purpose, Myoglobin (Myo) was selected as target analyte and its plastic antibody imprinted over a glutaraldehyde (Glu)/cysteamine (Cys) layer on the gold-surface. The imprinting effect was produced by growing a reticulated polymer of acrylamide (AAM) and N,N′-methylenebisacrylamide (NNMBA) around the Myo template, covalently attached to the biosensing surface. Electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) studies were carried out in all chemical modification steps to confirm the surface changes in the Au-SPE. The analytical features of the resulting biosensor were studied by different electrochemical techniques, including EIS, square wave voltammetry (SWV) and potentiometry. The limits of detection ranged from 0.13 to 8 μg/mL. Only potentiometry assays showed limits of detection including the cut-off Myo levels. Quantitative information was also produced for Myo concentrations ≥0.2 μg/mL. The linear response of the biosensing device showed an anionic slope of ~70 mV per decade molar concentration up to 0.3 μg/mL. The interference of coexisting species was tested and good selectivity was observed. The biosensor was successfully applied to biological fluids. |
RB Queirós, N de-los-Santos-Álvarez, JPC Noronha, MGF Sales A label-free DNA aptamer-based impedance biosensor for the detection of E. coli outer membrane proteins (Journal Article) Sensors and Actuators B: ChemicalSensors and Actuators B: Chemical, 181 , pp. 766–772, 2013. @article{Queirós2013b, title = {A label-free DNA aptamer-based impedance biosensor for the detection of E. coli outer membrane proteins}, author = {RB Queirós and N de-los-Santos-Álvarez and JPC Noronha and MGF Sales}, url = {http://www.sciencedirect.com/science/article/pii/S0925400513000798 http://recipp.ipp.pt/handle/10400.22/6733}, doi = { 10.1016/j.snb.2013.01.062}, year = {2013}, date = {2013-05-01}, journal = {Sensors and Actuators B: ChemicalSensors and Actuators B: Chemical}, volume = {181}, pages = {766–772}, abstract = {A label-free DNA aptamer-based impedance biosensor for the detection of E. coli outer membrane proteins (OMPs) was developed. Two single stranded DNA sequences were tested as recognition elements and compared. The aptamer capture probes were immobilized, with and without 6-mercapto-1-hexanol (MCH) on a gold electrode. Each step of the modification process was characterized by Faradaic impedance spectroscopy (FIS). A linear relationship between the electron-transfer resistance (Ret) and E. coli OMPs concentration was demonstrated in a dynamic detection range of 1 × 10−7–2 × 10−6 M. Moreover, the aptasensor showed selectivity despite the presence of other possible water contaminates and could be regenerated under low pH condition. The developed biosensor shows great potential to be incorporated in a biochip and used for in situ detection of E. coli OMPs in water samples.}, keywords = {}, pubstate = {published}, tppubtype = {article} } A label-free DNA aptamer-based impedance biosensor for the detection of E. coli outer membrane proteins (OMPs) was developed. Two single stranded DNA sequences were tested as recognition elements and compared. The aptamer capture probes were immobilized, with and without 6-mercapto-1-hexanol (MCH) on a gold electrode. Each step of the modification process was characterized by Faradaic impedance spectroscopy (FIS). A linear relationship between the electron-transfer resistance (Ret) and E. coli OMPs concentration was demonstrated in a dynamic detection range of 1 × 10−7–2 × 10−6 M. Moreover, the aptasensor showed selectivity despite the presence of other possible water contaminates and could be regenerated under low pH condition. The developed biosensor shows great potential to be incorporated in a biochip and used for in situ detection of E. coli OMPs in water samples. |
JRL Guerreiro, DS Sutherland, VAP Freitas, MGF Sales Protein–polyphenol interaction on silica beads for astringency tests based on eye, photography or reflectance detection modes (Journal Article) Analytical Methods, 5 (11), pp. 2694-2703, 2013. @article{Guerreiro2013, title = {Protein–polyphenol interaction on silica beads for astringency tests based on eye, photography or reflectance detection modes}, author = {JRL Guerreiro and DS Sutherland and VAP Freitas and MGF Sales}, url = {http://pubs.rsc.org/en/content/articlelanding/2013/ay/c3ay26478e#!divAbstract http://recipp.ipp.pt/handle/10400.22/6730}, doi = {10.1039/C3AY26478E}, year = {2013}, date = {2013-04-26}, journal = {Analytical Methods}, volume = {5}, number = {11}, pages = {2694-2703}, abstract = {Astringency is an organoleptic property of beverages and food products resulting mainly from the interaction of salivary proteins with dietary polyphenols. It is of great importance to consumers, but the only effective way of measuring it involves trained sensorial panellists, providing subjective and expensive responses. Concurrent chemical evaluations try to screen food astringency, by means of polyphenol and protein precipitation procedures, but these are far from the real human astringency sensation where not all polyphenol–protein interactions lead to the occurrence of precipitate. Here, a novel chemical approach that tries to mimic protein–polyphenol interactions in the mouth is presented to evaluate astringency. A protein, acting as a salivary protein, is attached to a solid support to which the polyphenol binds (just as happens when drinking wine), with subsequent colour alteration that is fully independent from the occurrence of precipitate. Employing this simple concept, Bovine Serum Albumin (BSA) was selected as the model salivary protein and used to cover the surface of silica beads. Tannic Acid (TA), employed as the model polyphenol, was allowed to interact with the BSA on the silica support and its adsorption to the protein was detected by reaction with Fe(III) and subsequent colour development. Quantitative data of TA in the samples were extracted by colorimetric or reflectance studies over the solid materials. The analysis was done by taking a regular picture with a digital camera, opening the image file in common software and extracting the colour coordinates from HSL (Hue, Saturation, Lightness) and RGB (Red, Green, Blue) colour model systems; linear ranges were observed from 10.6 to 106.0 μmol L−1. The latter was based on the Kubelka–Munk response, showing a linear gain with concentrations from 0.3 to 10.5 μmol L−1. In either of these two approaches, semi-quantitative estimation of TA was enabled by direct eye comparison. The correlation between the levels of adsorbed TA and the astringency of beverages was tested by using the assay to check the astringency of wines and comparing these to the response of sensorial panellists. Results of the two methods correlated well. The proposed sensor has significant potential as a robust tool for the quantitative/semi-quantitative evaluation of astringency in wine.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Astringency is an organoleptic property of beverages and food products resulting mainly from the interaction of salivary proteins with dietary polyphenols. It is of great importance to consumers, but the only effective way of measuring it involves trained sensorial panellists, providing subjective and expensive responses. Concurrent chemical evaluations try to screen food astringency, by means of polyphenol and protein precipitation procedures, but these are far from the real human astringency sensation where not all polyphenol–protein interactions lead to the occurrence of precipitate. Here, a novel chemical approach that tries to mimic protein–polyphenol interactions in the mouth is presented to evaluate astringency. A protein, acting as a salivary protein, is attached to a solid support to which the polyphenol binds (just as happens when drinking wine), with subsequent colour alteration that is fully independent from the occurrence of precipitate. Employing this simple concept, Bovine Serum Albumin (BSA) was selected as the model salivary protein and used to cover the surface of silica beads. Tannic Acid (TA), employed as the model polyphenol, was allowed to interact with the BSA on the silica support and its adsorption to the protein was detected by reaction with Fe(III) and subsequent colour development. Quantitative data of TA in the samples were extracted by colorimetric or reflectance studies over the solid materials. The analysis was done by taking a regular picture with a digital camera, opening the image file in common software and extracting the colour coordinates from HSL (Hue, Saturation, Lightness) and RGB (Red, Green, Blue) colour model systems; linear ranges were observed from 10.6 to 106.0 μmol L−1. The latter was based on the Kubelka–Munk response, showing a linear gain with concentrations from 0.3 to 10.5 μmol L−1. In either of these two approaches, semi-quantitative estimation of TA was enabled by direct eye comparison. The correlation between the levels of adsorbed TA and the astringency of beverages was tested by using the assay to check the astringency of wines and comparing these to the response of sensorial panellists. Results of the two methods correlated well. The proposed sensor has significant potential as a robust tool for the quantitative/semi-quantitative evaluation of astringency in wine. |
RB Queirós, PAR Tafulo, MGF Sales Combinatorial Chemistry & High Throughput Screening, 16 (1), pp. 22-31, 2013, ISSN: 1386-2073. @article{Queirós2013, title = {Assessing and comparing the total antioxidant capacity of commercial beverages: Application to beers, wines, waters and soft drinks using TRAP, TEAC and FRAP methods}, author = {RB Queirós and PAR Tafulo and MGF Sales }, url = {http://www.ncbi.nlm.nih.gov/pubmed/22931382 http://hdl.handle.net/10400.22/6746}, doi = {10.2174/1386207311316010004#sthash.DGDPA58e.dpuf}, issn = {1386-2073}, year = {2013}, date = {2013-01-01}, journal = {Combinatorial Chemistry & High Throughput Screening}, volume = {16}, number = {1}, pages = {22-31}, abstract = {This work measures and tries to compare the Antioxidant Capacity (AC) of 50 commercial beverages of different kinds: 6 wines, 12 beers, 18 soft drinks and 14 flavoured waters. Because there is no reference procedure established for this purpose, three different optical methods were used to analyse these samples: Total Radical trapping Antioxidant Parameter (TRAP), Trolox Equivalent Antioxidant Capacity (TEAC) and Ferric ion Reducing Antioxidant Parameter (FRAP). These methods differ on the chemical background and nature of redox system. The TRAP method involves the transfer of hydrogen atoms while TEAC and FRAP involves electron transfer reactions. The AC was also assessed against three antioxidants of reference, Ascorbic acid (AA), Gallic acid (GA) and 6-hydroxy-2,5,7,8-tetramethyl- 2-carboxylic acid (Trolox). The results obtained were analyzed statistically. Anova one-way tests were applied to all results and suggested that methods and standards exhibited significant statistical differences. The possible effect of sample features in the AC, such as gas, flavours, food colouring, sweeteners, acidity regulators, preservatives, stabilizers, vitamins, juice percentage, alcohol percentage, antioxidants and the colour was also investigated. The AC levels seemed to change with brand, kind of antioxidants added, and kind of flavour, depending on the sample. In general, higher ACs were obtained for FRAP as method, and beer for kind of sample, and the standard expressing the smaller AC values was GA.}, keywords = {}, pubstate = {published}, tppubtype = {article} } This work measures and tries to compare the Antioxidant Capacity (AC) of 50 commercial beverages of different kinds: 6 wines, 12 beers, 18 soft drinks and 14 flavoured waters. Because there is no reference procedure established for this purpose, three different optical methods were used to analyse these samples: Total Radical trapping Antioxidant Parameter (TRAP), Trolox Equivalent Antioxidant Capacity (TEAC) and Ferric ion Reducing Antioxidant Parameter (FRAP). These methods differ on the chemical background and nature of redox system. The TRAP method involves the transfer of hydrogen atoms while TEAC and FRAP involves electron transfer reactions. The AC was also assessed against three antioxidants of reference, Ascorbic acid (AA), Gallic acid (GA) and 6-hydroxy-2,5,7,8-tetramethyl- 2-carboxylic acid (Trolox). The results obtained were analyzed statistically. Anova one-way tests were applied to all results and suggested that methods and standards exhibited significant statistical differences. The possible effect of sample features in the AC, such as gas, flavours, food colouring, sweeteners, acidity regulators, preservatives, stabilizers, vitamins, juice percentage, alcohol percentage, antioxidants and the colour was also investigated. The AC levels seemed to change with brand, kind of antioxidants added, and kind of flavour, depending on the sample. In general, higher ACs were obtained for FRAP as method, and beer for kind of sample, and the standard expressing the smaller AC values was GA. |
FTC Moreira, RB Queirós, LAANA Truta, TIB Silva, RM Castro, LR Amorim, MGF Sales Host-tailored sensors for leucomalachite green potentiometric measurements (Journal Article) Journal of Chemistry, 2013 (Article ID 605403), pp. 13, 2013. @article{Moreira2013b, title = {Host-tailored sensors for leucomalachite green potentiometric measurements}, author = {FTC Moreira and RB Queirós and LAANA Truta and TIB Silva and RM Castro and LR Amorim and MGF Sales}, url = {http://www.hindawi.com/journals/jchem/2013/605403/ http://recipp.ipp.pt/handle/10400.22/6734}, doi = {10.1155/2013/605403}, year = {2013}, date = {2013-01-01}, journal = {Journal of Chemistry}, volume = {2013}, number = {Article ID 605403}, pages = {13}, abstract = {A new biomimetic sensor for leucomalachite green host-guest interactions and potentiometric transduction is presented. The artificial host was imprinted in methacrylic acid or acrylamido-2-methyl-1-propanesulfonic acid-based polymers. Molecularly imprinted particles were dispersed in 2-nitrophenyloctyl ether and trapped in poly(vinyl chloride). The potentiometric sensors exhibited a near-Nernstian response in steady state evaluations, with slopes and detection limits ranging from 45.8 to 81.2 mV and 0.28 to 1.01 , respectively. They were independent from the pH of test solutions within 3 to 5. Good selectivity was observed towards drugs that may contaminate water near fish cultures, such as oxycycline, doxycycline, enrofloxacin, trimethoprim, creatinine, chloramphenicol, and dopamine. The sensors were successfully applied to field monitoring of leucomalachite green in river samples. The method offered the advantages of simplicity, accuracy, applicability to colored and turbid samples, and automation feasibility.}, keywords = {}, pubstate = {published}, tppubtype = {article} } A new biomimetic sensor for leucomalachite green host-guest interactions and potentiometric transduction is presented. The artificial host was imprinted in methacrylic acid or acrylamido-2-methyl-1-propanesulfonic acid-based polymers. Molecularly imprinted particles were dispersed in 2-nitrophenyloctyl ether and trapped in poly(vinyl chloride). The potentiometric sensors exhibited a near-Nernstian response in steady state evaluations, with slopes and detection limits ranging from 45.8 to 81.2 mV and 0.28 to 1.01 , respectively. They were independent from the pH of test solutions within 3 to 5. Good selectivity was observed towards drugs that may contaminate water near fish cultures, such as oxycycline, doxycycline, enrofloxacin, trimethoprim, creatinine, chloramphenicol, and dopamine. The sensors were successfully applied to field monitoring of leucomalachite green in river samples. The method offered the advantages of simplicity, accuracy, applicability to colored and turbid samples, and automation feasibility. |
2012
Queirós, RB; Noronha, JPC; Marques, PVS; Sales, MGF Label-free detection of microcystin-LR in waters using real-time potentiometric biosensors based on single-walled carbon nanotubes imprinted polymers (Journal Article) Procedia Engineering, 47 , pp. 758–761, 2012. @article{Queirós2012b, title = {Label-free detection of microcystin-LR in waters using real-time potentiometric biosensors based on single-walled carbon nanotubes imprinted polymers}, author = {RB Queirós and JPC Noronha and PVS Marques and MGF Sales}, url = {http://www.sciencedirect.com/science/article/pii/S1877705812043214 http://recipp.ipp.pt/handle/10400.22/6744}, doi = {10.1016/j.proeng.2012.09.258}, year = {2012}, date = {2012-09-09}, journal = {Procedia Engineering}, volume = {47}, pages = {758–761}, abstract = {Microcystin-LR (MC-LR) is a dangerous toxin found in environmental waters, quantified by high performance liquid chromatography and/or enzyme-linked immunosorbent assays. Quick, low cost and on-site analysis is thus required to ensure human safety and wide screening programs. This work proposes label-free potentiometric sensors made of solid-contact electrodes coated with a surface imprinted polymer on the surface of Multi-Walled Carbon NanoTubes (CNTs) incorporated in a polyvinyl chloride membrane. The imprinting effect was checked by using non-imprinted materials. The MC-LR sensitive sensors were evaluated, characterized and applied successfully in spiked environmental waters. The presented method offered the advantages of low cost, portability, easy operation and suitability for adaptation to flow methods.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Microcystin-LR (MC-LR) is a dangerous toxin found in environmental waters, quantified by high performance liquid chromatography and/or enzyme-linked immunosorbent assays. Quick, low cost and on-site analysis is thus required to ensure human safety and wide screening programs. This work proposes label-free potentiometric sensors made of solid-contact electrodes coated with a surface imprinted polymer on the surface of Multi-Walled Carbon NanoTubes (CNTs) incorporated in a polyvinyl chloride membrane. The imprinting effect was checked by using non-imprinted materials. The MC-LR sensitive sensors were evaluated, characterized and applied successfully in spiked environmental waters. The presented method offered the advantages of low cost, portability, easy operation and suitability for adaptation to flow methods. |
Moreira, FTC; Guerreiro, JRL; Barros, R; Sales, MGF The effect of method, standard and sample components on the total antioxidant capacity of commercial waters assessed by optical conventional assays (Journal Article) Food Chemistry, 134 (1), pp. 564–571, 2012. @article{Moreira2012, title = {The effect of method, standard and sample components on the total antioxidant capacity of commercial waters assessed by optical conventional assays}, author = {FTC Moreira and JRL Guerreiro and R Barros and MGF Sales }, url = {http://www.sciencedirect.com/science/article/pii/S030881461200310X http://recipp.ipp.pt/handle/10400.22/6747}, doi = {10.1016/j.foodchem.2012.02.122}, year = {2012}, date = {2012-09-01}, journal = {Food Chemistry}, volume = {134}, number = {1}, pages = {564–571}, abstract = {The total antioxidant capacity (TAC) of 28 flavoured water samples was assessed by ferric reducing antioxidant potential (FRAP), oxygen radical absorbance capacity (ORAC), trolox equivalent antioxidant capacity (TEAC) and total reactive antioxidant potential (TRAP) methods. It was observed that flavoured waters had higher antioxidant activity than the corresponding natural ones. The observed differences were attributed to flavours, juice and vitamins. Generally, higher TAC contents were obtained on lemon waters and lower values on guava and raspberry flavoured waters. Lower and higher TACs were obtained by TRAP and ORAC method, respectively. Statistical analysis suggested that vitamins and flavours increased the antioxidant content of the commercial waters}, keywords = {}, pubstate = {published}, tppubtype = {article} } The total antioxidant capacity (TAC) of 28 flavoured water samples was assessed by ferric reducing antioxidant potential (FRAP), oxygen radical absorbance capacity (ORAC), trolox equivalent antioxidant capacity (TEAC) and total reactive antioxidant potential (TRAP) methods. It was observed that flavoured waters had higher antioxidant activity than the corresponding natural ones. The observed differences were attributed to flavours, juice and vitamins. Generally, higher TAC contents were obtained on lemon waters and lower values on guava and raspberry flavoured waters. Lower and higher TACs were obtained by TRAP and ORAC method, respectively. Statistical analysis suggested that vitamins and flavours increased the antioxidant content of the commercial waters |
Moreira, FTC; Dutra, RAF; Noronha, JPC; Sales, MGF Surface imprinting approach on screen printed electrodes coated with carboxylated PVC for myoglobin detection with electrochemical transduction (Journal Article) Procedia Engineering, 47 , pp. 865–868, 2012. @article{FTC2012, title = {Surface imprinting approach on screen printed electrodes coated with carboxylated PVC for myoglobin detection with electrochemical transduction}, author = {FTC Moreira and RAF Dutra and JPC Noronha and MGF Sales}, url = {http://www.sciencedirect.com/science/article/pii/S1877705812043470 http://recipp.ipp.pt/handle/10400.22/6743}, doi = {10.1016/j.proeng.2012.09.284}, year = {2012}, date = {2012-09-01}, journal = {Procedia Engineering}, volume = {47}, pages = {865–868}, abstract = {A novel surface molecularly-imprinted (MI) material to detect myoglobin (Myo) using gold screen printed electrodes (SPE) was developed. The sensitive detection was carry out by introducing a carboxylic polyvinyl chloride (PVC-COOH) layer on gold SPE surface. Myo was attached to the surface of gold SPE/PVC-COOH and the vacant spaces around it were filled by polymerizing acrylamide and N,N-methylenebisacrylamide (cross-linker). This polymerization was initiated by ammonium persulphate. After removing the template, the obtained material was able to rebind Myo and discriminate it among other interfering species. Various characterization techniques including electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) confirmed the surface modification. This sensor seemed a promising tool for screening Myo in point-of-care.}, keywords = {}, pubstate = {published}, tppubtype = {article} } A novel surface molecularly-imprinted (MI) material to detect myoglobin (Myo) using gold screen printed electrodes (SPE) was developed. The sensitive detection was carry out by introducing a carboxylic polyvinyl chloride (PVC-COOH) layer on gold SPE surface. Myo was attached to the surface of gold SPE/PVC-COOH and the vacant spaces around it were filled by polymerizing acrylamide and N,N-methylenebisacrylamide (cross-linker). This polymerization was initiated by ammonium persulphate. After removing the template, the obtained material was able to rebind Myo and discriminate it among other interfering species. Various characterization techniques including electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) confirmed the surface modification. This sensor seemed a promising tool for screening Myo in point-of-care. |
Guerreiro, JRL; Freitas, VAP; Sutherland, DS; Sales, MGF SPR based studies for pentagalloyl glucose binding to α-amylase (Journal Article) Procedia Engineering, 47 , pp. 498–501, 2012. @article{Guerreiro2012, title = {SPR based studies for pentagalloyl glucose binding to α-amylase}, author = {JRL Guerreiro and VAP Freitas and DS Sutherland and MGF Sales}, url = {http://www.sciencedirect.com/science/article/pii/S1877705812042567 http://recipp.ipp.pt/handle/10400.22/6745}, doi = {10.1016/j.proeng.2012.09.193}, year = {2012}, date = {2012-09-01}, journal = {Procedia Engineering}, volume = {47}, pages = {498–501}, abstract = {Astringency is an organoleptic property resulting mostly from the interaction of salivary proteins with dietary polyphenols. It is of great importance to consumers but being typically measured by sensorial panels it turns out subjective and expensive. The main goal of the present work is to develop a sensory system to estimate astringency relying on protein/polyphenol interactions. For this purpose, a model protein was immobilized on a sensory gold surface and its subsequent interaction with polyphenols was measured by Surface Plasma Resonance (SPR). α-amylase and pentagalloyl glucose (PGG) were selected as model protein and polyphenol, respectively. To ensure specific binding between these, various surface chemistries were tested. Carboxylic terminated thiol decreased the binding ability of PGG and allowed covalent attachment of α-amylase to the surface. The pH 5 was the optimal condition for α-amylase immobilization on the surface. Further studies focus on Localized SPR sensor and application to wine samples, providing objectivity when compared to a trained panel.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Astringency is an organoleptic property resulting mostly from the interaction of salivary proteins with dietary polyphenols. It is of great importance to consumers but being typically measured by sensorial panels it turns out subjective and expensive. The main goal of the present work is to develop a sensory system to estimate astringency relying on protein/polyphenol interactions. For this purpose, a model protein was immobilized on a sensory gold surface and its subsequent interaction with polyphenols was measured by Surface Plasma Resonance (SPR). α-amylase and pentagalloyl glucose (PGG) were selected as model protein and polyphenol, respectively. To ensure specific binding between these, various surface chemistries were tested. Carboxylic terminated thiol decreased the binding ability of PGG and allowed covalent attachment of α-amylase to the surface. The pH 5 was the optimal condition for α-amylase immobilization on the surface. Further studies focus on Localized SPR sensor and application to wine samples, providing objectivity when compared to a trained panel. |
Silva, TIB; Moreira, FTC; Truta, LAANA; Sales, MGF Biosensors and Bioelectronics, 36 (1), pp. 199–206, 2012. @article{Silva2012, title = {Novel optical PVC probes for on-site detection/determination of fluoroquinolones in a solid/liquid interface: Application to the determination of Norfloxacin in aquaculture water}, author = {TIB Silva and FTC Moreira and LAANA Truta and MGF Sales}, url = {http://www.sciencedirect.com/science/article/pii/S0956566312002345 http://recipp.ipp.pt/handle/10400.22/6748}, doi = {10.1016/j.bios.2012.04.018}, year = {2012}, date = {2012-07-01}, journal = {Biosensors and Bioelectronics}, volume = {36}, number = {1}, pages = {199–206}, abstract = {A novel optical disposable probe for screening fluoroquinolones in fish farming waters is presented, having Norfloxacin (NFX) as target compound. The colorimetric reaction takes place in the solid/liquid interface consisting of a plasticized PVC layer carrying the colorimetric reagent and the sample solution. NFX solutions dropped on top of this solid-sensory surface provided a colour change from light yellow to dark orange. Several metals were tested as colorimetric reagents and Fe(III) was selected. The main parameters affecting the obtained colour were assessed and optimised in both liquid and solid phases. The corresponding studies were conducted by visible spectrophotometry and digital image acquisition. The three coordinates of the HSL model system of the collected image (Hue, Saturation and Lightness) were obtained by simple image management (enabled in any computer). The analytical response of the optimised solid-state optical probe against concentration was tested for several mathematical transformations of the colour coordinates. Linear behaviour was observed for logarithm NFX concentration against Hue+Lightness. Under this condition, the sensor exhibited a limit of detection below 50 μM (corresponding to about 16 mg/mL). Visual inspection also enabled semi-quantitative information. The selectivity was ensured against drugs from other chemical groups than fluoroquinolones. Finally, similar procedure was used to prepare an array of sensors for NFX, consisting on different metal species. Cu(II), Mn(II) and aluminon were selected for this purpose. The sensor array was used to detect NFX in aquaculture water, without any prior sample manipulation.}, keywords = {}, pubstate = {published}, tppubtype = {article} } A novel optical disposable probe for screening fluoroquinolones in fish farming waters is presented, having Norfloxacin (NFX) as target compound. The colorimetric reaction takes place in the solid/liquid interface consisting of a plasticized PVC layer carrying the colorimetric reagent and the sample solution. NFX solutions dropped on top of this solid-sensory surface provided a colour change from light yellow to dark orange. Several metals were tested as colorimetric reagents and Fe(III) was selected. The main parameters affecting the obtained colour were assessed and optimised in both liquid and solid phases. The corresponding studies were conducted by visible spectrophotometry and digital image acquisition. The three coordinates of the HSL model system of the collected image (Hue, Saturation and Lightness) were obtained by simple image management (enabled in any computer). The analytical response of the optimised solid-state optical probe against concentration was tested for several mathematical transformations of the colour coordinates. Linear behaviour was observed for logarithm NFX concentration against Hue+Lightness. Under this condition, the sensor exhibited a limit of detection below 50 μM (corresponding to about 16 mg/mL). Visual inspection also enabled semi-quantitative information. The selectivity was ensured against drugs from other chemical groups than fluoroquinolones. Finally, similar procedure was used to prepare an array of sensors for NFX, consisting on different metal species. Cu(II), Mn(II) and aluminon were selected for this purpose. The sensor array was used to detect NFX in aquaculture water, without any prior sample manipulation. |
Almeida, SAA; Truta, LAANA; Queirós, RB; Montenegro, MCBSM; Cunha, AL; Sales, MGF Optimizing potentiometric ionophore and electrode design for environmental on-site control of antibiotic drugs: Application to sulfamethoxazole (Journal Article) Biosensors and Bioelectronics, 35 (1), pp. 319–326, 2012. @article{Almeida2012, title = {Optimizing potentiometric ionophore and electrode design for environmental on-site control of antibiotic drugs: Application to sulfamethoxazole}, author = {SAA Almeida and LAANA Truta and RB Queirós and MCBSM Montenegro and AL Cunha and MGF Sales }, url = {http://www.sciencedirect.com/science/article/pii/S095656631200173X http://recipp.ipp.pt/handle/10400.22/6749 }, doi = {10.1016/j.bios.2012.03.007}, year = {2012}, date = {2012-05-15}, journal = {Biosensors and Bioelectronics}, volume = {35}, number = {1}, pages = {319–326}, abstract = {Potentiometric sensors are typically unable to carry out on-site monitoring of environmental drug contaminants because of their high limits of detection (LODs). Designing a novel ligand material for the target analyte and managing the composition of the internal reference solution have been the strategies employed here to produce for the first time a potentiometric-based direct reading method for an environmental drug contaminant. This concept has been applied to sulfamethoxazole (SMX), one of the many antibiotics used in aquaculture practices that may occur in environmental waters. The novel ligand has been produced by imprinting SMX on the surface of graphitic carbon nanostructures (CN) < 500 nm. The imprinted carbon nanostructures (ICN) were dispersed in plasticizer and entrapped in a PVC matrix that included (or not) a small amount of a lipophilic additive. The membrane composition was optimized on solid-contact electrodes, allowing near-Nernstian responses down to 5.2 μg/mL and detecting 1.6 μg/mL. The membranes offered good selectivity against most of the ionic compounds in environmental water. The best membrane cocktail was applied on the smaller end of a 1000 μL micropipette tip made of polypropylene. The tip was then filled with inner reference solution containing SMX and chlorate (as interfering compound). The corresponding concentrations were studied for 1 × 10−5 to 1 × 10−10 and 1 × 10−3 to 1 × 10−8 mol/L. The best condition allowed the detection of 5.92 ng/L (or 2.3 × 10−8 mol/L) SMX for a sub-Nernstian slope of −40.3 mV/decade from 5.0 × 10−8 to 2.4 × 10−5 mol/L. The described sensors were found promising devices for field applications. The good selectivity of the sensory materials together with a carefully selected composition for the inner reference solution allowed LODs near the nanomolar range. Both solid-contact and “pipette tip”-based sensors were successfully applied to the analysis of aquaculture waters.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Potentiometric sensors are typically unable to carry out on-site monitoring of environmental drug contaminants because of their high limits of detection (LODs). Designing a novel ligand material for the target analyte and managing the composition of the internal reference solution have been the strategies employed here to produce for the first time a potentiometric-based direct reading method for an environmental drug contaminant. This concept has been applied to sulfamethoxazole (SMX), one of the many antibiotics used in aquaculture practices that may occur in environmental waters. The novel ligand has been produced by imprinting SMX on the surface of graphitic carbon nanostructures (CN) < 500 nm. The imprinted carbon nanostructures (ICN) were dispersed in plasticizer and entrapped in a PVC matrix that included (or not) a small amount of a lipophilic additive. The membrane composition was optimized on solid-contact electrodes, allowing near-Nernstian responses down to 5.2 μg/mL and detecting 1.6 μg/mL. The membranes offered good selectivity against most of the ionic compounds in environmental water. The best membrane cocktail was applied on the smaller end of a 1000 μL micropipette tip made of polypropylene. The tip was then filled with inner reference solution containing SMX and chlorate (as interfering compound). The corresponding concentrations were studied for 1 × 10−5 to 1 × 10−10 and 1 × 10−3 to 1 × 10−8 mol/L. The best condition allowed the detection of 5.92 ng/L (or 2.3 × 10−8 mol/L) SMX for a sub-Nernstian slope of −40.3 mV/decade from 5.0 × 10−8 to 2.4 × 10−5 mol/L. The described sensors were found promising devices for field applications. The good selectivity of the sensory materials together with a carefully selected composition for the inner reference solution allowed LODs near the nanomolar range. Both solid-contact and “pipette tip”-based sensors were successfully applied to the analysis of aquaculture waters. |
Queiros, RB; Noronha, JPC; Marques, PVS; Fernandes, JS; Sales, MGF Determination of Microcystin-LR in waters in the subnanomolar range by sol–gel imprinted polymers on solid contact electrodes (Journal Article) Analyst, 137 (10), pp. 2437-2444, 2012. @article{Queiros2012, title = {Determination of Microcystin-LR in waters in the subnanomolar range by sol–gel imprinted polymers on solid contact electrodes}, author = {RB Queiros and JPC Noronha and PVS Marques and JS Fernandes and MGF Sales}, url = {http://pubs.rsc.org/en/Content/ArticleLanding/2012/AN/c2an35141b#!divAbstract http://hdl.handle.net/10400.22/6750}, doi = {10.1039/C2AN35141B}, year = {2012}, date = {2012-03-22}, journal = {Analyst}, volume = {137}, number = {10}, pages = {2437-2444}, abstract = {The present work reports new sensors for the direct determination of Microcystin-LR (MC-LR) in environmental waters. Both selective membrane and solid contact were optimized to ensure suitable analytical features in potentiometric transduction. The sensing layer consisted of Imprinted Sol–Gel (ISG) materials capable of establishing surface interactions with MC-LR. Non-Imprinted Sol–Gel (NISG) membranes were used as negative control. The effects of an ionic lipophilic additive, time of sol–gel polymerization, time of extraction of MC-LR from the sensitive layer, and pH were also studied. The solid contact was made of carbon, aluminium, titanium, copper or nickel/chromium alloys (80 : 20 or 90 : 10). The best ISG sensor had a carbon solid contact and displayed average slopes of 211.3 mV per decade, with detection limits of 7.3 × 10−10 M, corresponding to 0.75 μg L−1. It showed linear responses in the range of 7.7 × 10−10 to 1.9 × 10−9 M of MC-LR (corresponding to 0.77–2.00 μg L−1), thus including the limiting value for MC-LR in waters (1.0 μg L−1). The potentiometric-selectivity coefficients were assessed by the matched potential method for ionic species regularly found in waters up to their limiting levels. Chloride (Cl−) showed limited interference while aluminium (Al3+), ammonium (NH4+), magnesium (Mg2+), manganese (Mn2+), sodium (Na+), and sulfate (SO42−) were unable to cause the required potential change. Spiked solutions were tested with the proposed sensor. The relative errors and standard deviation obtained confirmed the accuracy and precision of the method. It also offered the advantages of low cost, portability, easy operation and suitability for adaptation to flow methods.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The present work reports new sensors for the direct determination of Microcystin-LR (MC-LR) in environmental waters. Both selective membrane and solid contact were optimized to ensure suitable analytical features in potentiometric transduction. The sensing layer consisted of Imprinted Sol–Gel (ISG) materials capable of establishing surface interactions with MC-LR. Non-Imprinted Sol–Gel (NISG) membranes were used as negative control. The effects of an ionic lipophilic additive, time of sol–gel polymerization, time of extraction of MC-LR from the sensitive layer, and pH were also studied. The solid contact was made of carbon, aluminium, titanium, copper or nickel/chromium alloys (80 : 20 or 90 : 10). The best ISG sensor had a carbon solid contact and displayed average slopes of 211.3 mV per decade, with detection limits of 7.3 × 10−10 M, corresponding to 0.75 μg L−1. It showed linear responses in the range of 7.7 × 10−10 to 1.9 × 10−9 M of MC-LR (corresponding to 0.77–2.00 μg L−1), thus including the limiting value for MC-LR in waters (1.0 μg L−1). The potentiometric-selectivity coefficients were assessed by the matched potential method for ionic species regularly found in waters up to their limiting levels. Chloride (Cl−) showed limited interference while aluminium (Al3+), ammonium (NH4+), magnesium (Mg2+), manganese (Mn2+), sodium (Na+), and sulfate (SO42−) were unable to cause the required potential change. Spiked solutions were tested with the proposed sensor. The relative errors and standard deviation obtained confirmed the accuracy and precision of the method. It also offered the advantages of low cost, portability, easy operation and suitability for adaptation to flow methods. |
Almeida, SAA; Heitor, AM; Sa, LC; Barbosa, J; Montenegro, MCBSM; Sales, MGF International Journal of Environmental Analytical Chemistry, 92 (4), pp. 479-495, 2012. @article{Almeida2012b, title = {Solid contact PVC membrane electrodes based on neutral or charged carriers for the selective reading of anionic sulfamethoxazole and their application to the analysis of aquaculture water}, author = {SAA Almeida and AM Heitor and LC Sa and J Barbosa and MCBSM Montenegro and MGF Sales}, url = {http://www.tandfonline.com/doi/abs/10.1080/03067319.2011.585717 http://recipp.ipp.pt/handle/10400.22/6751}, doi = {10.1080/03067319.2011.585717}, year = {2012}, date = {2012-01-01}, journal = { International Journal of Environmental Analytical Chemistry}, volume = {92}, number = {4}, pages = {479-495}, abstract = {Sulfamethoxazole (SMX) is among the antibiotics employed in aquaculture for prophylactic and therapeutic reasons. Environmental and food spread may be prevented by controlling its levels in several stages of fish farming. The present work proposes for this purpose new SMX selective electrodes for the potentiometric determination of this sulphonamide in water. The selective membranes were made of polyvinyl chloride (PVC) with tetraphenylporphyrin manganese (III) chloride or cyclodextrin-based acting as ionophores. 2-nitrophenyl octyl ether was employed as plasticizer and tetraoctylammonium, dimethyldioctadecylammonium bromide or potassium tetrakis (4-chlorophenyl) borate was used as anionic or cationic additive. The best analytical performance was reported for ISEs of tetraphenylporphyrin manganese (III) chloride with 50% mol of potassium tetrakis (4-chlorophenyl) borate compared to ionophore. Nersntian behaviour was observed from 4.0 × 10−5 to 1.0 × 10−2 mol/L (10.0 to 2500 µg/mL), and the limit of detection was 1.2 × 10−5 mol/L (3.0 µg/mL). In general, the electrodes displayed steady potentials in the pH range of 6 to 9. Emf equilibrium was reached before 15 s in all concentration levels. The electrodes revealed good discriminating ability in environmental samples. The analytical application to contaminated waters showed recoveries from 96 to 106%.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Sulfamethoxazole (SMX) is among the antibiotics employed in aquaculture for prophylactic and therapeutic reasons. Environmental and food spread may be prevented by controlling its levels in several stages of fish farming. The present work proposes for this purpose new SMX selective electrodes for the potentiometric determination of this sulphonamide in water. The selective membranes were made of polyvinyl chloride (PVC) with tetraphenylporphyrin manganese (III) chloride or cyclodextrin-based acting as ionophores. 2-nitrophenyl octyl ether was employed as plasticizer and tetraoctylammonium, dimethyldioctadecylammonium bromide or potassium tetrakis (4-chlorophenyl) borate was used as anionic or cationic additive. The best analytical performance was reported for ISEs of tetraphenylporphyrin manganese (III) chloride with 50% mol of potassium tetrakis (4-chlorophenyl) borate compared to ionophore. Nersntian behaviour was observed from 4.0 × 10−5 to 1.0 × 10−2 mol/L (10.0 to 2500 µg/mL), and the limit of detection was 1.2 × 10−5 mol/L (3.0 µg/mL). In general, the electrodes displayed steady potentials in the pH range of 6 to 9. Emf equilibrium was reached before 15 s in all concentration levels. The electrodes revealed good discriminating ability in environmental samples. The analytical application to contaminated waters showed recoveries from 96 to 106%. |
2011
SAA Almeida, E Arasa, M Puyol, CS Martinez-Cisneros, J Alonso-Chamarro, MCBSM Montenegro, MGF Sales Biosensors and Bioelectronics, 30 (1), pp. 197-203, 2011. @article{Almeida2011b, title = {Novel LTCC-potentiometric microfluidic device for biparametric analysis of organic compounds carrying plastic antibodies as ionophores: Application to sulfamethoxazole and trimethoprim}, author = {SAA Almeida and E Arasa and M Puyol and CS Martinez-Cisneros and J Alonso-Chamarro and MCBSM Montenegro and MGF Sales}, url = {http://www.sciencedirect.com/science/article/pii/S0956566311006117 http://recipp.ipp.pt/handle/10400.22/6755}, doi = {10.1016/j.bios.2011.09.011}, year = {2011}, date = {2011-12-15}, journal = {Biosensors and Bioelectronics}, volume = {30}, number = {1}, pages = {197-203}, abstract = {Monitoring organic environmental contaminants is of crucial importance to ensure public health. This requires simple, portable and robust devices to carry out on-site analysis. For this purpose, a low-temperature co-fired ceramics (LTCC) microfluidic potentiometric device (LTCC/μPOT) was developed for the first time for an organic compound: sulfamethoxazole (SMX). Sensory materials relied on newly designed plastic antibodies. Sol–gel, self-assembling monolayer and molecular-imprinting techniques were merged for this purpose. Silica beads were amine-modified and linked to SMX via glutaraldehyde modification. Condensation polymerization was conducted around SMX to fill the vacant spaces. SMX was removed after, leaving behind imprinted sites of complementary shape. The obtained particles were used as ionophores in plasticized PVC membranes. The most suitable membrane composition was selected in steady-state assays. Its suitability to flow analysis was verified in flow-injection studies with regular tubular electrodes. The LTCC/μPOT device integrated a bidimensional mixer, an embedded reference electrode based on Ag/AgCl and an Ag-based contact screen-printed under a micromachined cavity of 600 μm depth. The sensing membranes were deposited over this contact and acted as indicating electrodes. Under optimum conditions, the SMX sensor displayed slopes of about −58.7 mV/decade in a range from 12.7 to 250 μg/mL, providing a detection limit of 3.85 μg/mL and a sampling throughput of 36 samples/h with a reagent consumption of 3.3 mL per sample. The system was adjusted later to multiple analyte detection by including a second potentiometric cell on the LTCC/μPOT device. No additional reference electrode was required. This concept was applied to Trimethoprim (TMP), always administered concomitantly with sulphonamide drugs, and tested in fish-farming waters. The biparametric microanalyzer displayed Nernstian behaviour, with average slopes −54.7 (SMX) and +57.8 (TMP) mV/decade. To demonstrate the microanalyzer capabilities for real applications, it was successfully applied to single and simultaneous determination of SMX and TMP in aquaculture waters.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Monitoring organic environmental contaminants is of crucial importance to ensure public health. This requires simple, portable and robust devices to carry out on-site analysis. For this purpose, a low-temperature co-fired ceramics (LTCC) microfluidic potentiometric device (LTCC/μPOT) was developed for the first time for an organic compound: sulfamethoxazole (SMX). Sensory materials relied on newly designed plastic antibodies. Sol–gel, self-assembling monolayer and molecular-imprinting techniques were merged for this purpose. Silica beads were amine-modified and linked to SMX via glutaraldehyde modification. Condensation polymerization was conducted around SMX to fill the vacant spaces. SMX was removed after, leaving behind imprinted sites of complementary shape. The obtained particles were used as ionophores in plasticized PVC membranes. The most suitable membrane composition was selected in steady-state assays. Its suitability to flow analysis was verified in flow-injection studies with regular tubular electrodes. The LTCC/μPOT device integrated a bidimensional mixer, an embedded reference electrode based on Ag/AgCl and an Ag-based contact screen-printed under a micromachined cavity of 600 μm depth. The sensing membranes were deposited over this contact and acted as indicating electrodes. Under optimum conditions, the SMX sensor displayed slopes of about −58.7 mV/decade in a range from 12.7 to 250 μg/mL, providing a detection limit of 3.85 μg/mL and a sampling throughput of 36 samples/h with a reagent consumption of 3.3 mL per sample. The system was adjusted later to multiple analyte detection by including a second potentiometric cell on the LTCC/μPOT device. No additional reference electrode was required. This concept was applied to Trimethoprim (TMP), always administered concomitantly with sulphonamide drugs, and tested in fish-farming waters. The biparametric microanalyzer displayed Nernstian behaviour, with average slopes −54.7 (SMX) and +57.8 (TMP) mV/decade. To demonstrate the microanalyzer capabilities for real applications, it was successfully applied to single and simultaneous determination of SMX and TMP in aquaculture waters. |
SAA Almeida, FTC Moreira, AM Heitor, MCBSM Montenegro, GG Aguilar, MGF Sales Sulphonamide-imprinted sol–gel materials as ionophores in potentiometric transduction (Journal Article) Materials Science and Engineering: C, 31 (8), pp. 1784-1790, 2011. @article{Almeida2011b, title = {Sulphonamide-imprinted sol–gel materials as ionophores in potentiometric transduction}, author = {SAA Almeida and FTC Moreira and AM Heitor and MCBSM Montenegro and GG Aguilar and MGF Sales}, url = {http://www.sciencedirect.com/science/article/pii/S0928493111002360 http://recipp.ipp.pt/handle/10400.22/6760}, doi = {10.1016/j.msec.2011.08.011}, year = {2011}, date = {2011-12-01}, journal = {Materials Science and Engineering: C}, volume = {31}, number = {8}, pages = {1784-1790}, abstract = {This work proposes different kind of solid-contact graphite-based electrodes for the selective determination of sulphonamides (SPHs) in pharmaceuticals, biological fluids and aquaculture waters. Sulfadiazine (SDZ) and sulfamethoxazole (SMX) were selected for this purpose for being the most representative compounds of this group. The template molecules were imprinted in sol–gel (ISG) and the resulting material was used as detecting element. This was made by employing it as either a sensing layer or an ionophore of PVC-based membranes and subsequent potentiometric transduction, a strategy never reported before. The corresponding non-imprinted sol–gel (NISG) membranes were used as blank. The effect of plasticizer and kind/charge of ionic lipophilic additive was also studied. The best performance in terms of slope, linearity ranges and signal reproducibility and repeatability was achieved by PVC membranes including a high dielectric constant plasticizer and 15 mg of ISG particles. The corresponding average slope was −51.4 and −52.4 mV/decade, linear responses were 9.0 × 10−6 and 1.7 × 10−5 M, and limits of detection were 0.74 and 1.3 μg/mL for SDZ and for SMX, respectively. Good selectivity with log Kpot < −0.3 was observed for carbonate, chloride, fluoride, hydrogenocarbonate, nitrate, nitrite, phosphate, cyanide, sulfate, borate, persulphate, citrate, tartrate, salicylate, tetracycline, ciprofloxacin, sulphamerazine, sulphatiazole, dopamine, glucose, galactose, cysteine and creatinine. The best sensors were successfully applied to the analysis of real samples with relative errors ranging from −6.8 to + 3.7%.}, keywords = {}, pubstate = {published}, tppubtype = {article} } This work proposes different kind of solid-contact graphite-based electrodes for the selective determination of sulphonamides (SPHs) in pharmaceuticals, biological fluids and aquaculture waters. Sulfadiazine (SDZ) and sulfamethoxazole (SMX) were selected for this purpose for being the most representative compounds of this group. The template molecules were imprinted in sol–gel (ISG) and the resulting material was used as detecting element. This was made by employing it as either a sensing layer or an ionophore of PVC-based membranes and subsequent potentiometric transduction, a strategy never reported before. The corresponding non-imprinted sol–gel (NISG) membranes were used as blank. The effect of plasticizer and kind/charge of ionic lipophilic additive was also studied. The best performance in terms of slope, linearity ranges and signal reproducibility and repeatability was achieved by PVC membranes including a high dielectric constant plasticizer and 15 mg of ISG particles. The corresponding average slope was −51.4 and −52.4 mV/decade, linear responses were 9.0 × 10−6 and 1.7 × 10−5 M, and limits of detection were 0.74 and 1.3 μg/mL for SDZ and for SMX, respectively. Good selectivity with log Kpot < −0.3 was observed for carbonate, chloride, fluoride, hydrogenocarbonate, nitrate, nitrite, phosphate, cyanide, sulfate, borate, persulphate, citrate, tartrate, salicylate, tetracycline, ciprofloxacin, sulphamerazine, sulphatiazole, dopamine, glucose, galactose, cysteine and creatinine. The best sensors were successfully applied to the analysis of real samples with relative errors ranging from −6.8 to + 3.7%. |
JRL Guerreiro, MGF Sales Disposable solid state probe for optical screening of chlorpromazine (Journal Article) Microchimica Acta, 175 (3), pp. 323-331, 2011. @article{Guerreiro2011b, title = {Disposable solid state probe for optical screening of chlorpromazine}, author = {JRL Guerreiro and MGF Sales }, url = {http://link.springer.com/article/10.1007%2Fs00604-011-0671-7 http://recipp.ipp.pt/handle/10400.22/6759}, doi = {10.1007/s00604-011-0671-7}, year = {2011}, date = {2011-12-01}, journal = {Microchimica Acta}, volume = {175}, number = {3}, pages = {323-331}, abstract = {We are presenting a simple, low-cost and rapid solid-state optical probe for screening chlorpromazine (CPZ) in aquacultures. The method exploits the colourimetric reaction between CPZ and Fe(III) ion that occurs at a solid/liquid interface, the solid layer consisting of ferric iron entrapped in a layer of plasticized PVC. If solutions containing CPZ are dropped onto such a layer, a colour change occurs from light yellow to dark pink or even light blue, depending on the concentration of CPZ. Visual inspection enables the concentration of CPZ to be estimated. The resulting colouration was also monitored by digital image collection for a more accurate quantification. The three coordinates of the hue, saturation and lightness system were obtained by standard image processing along with mathematical data treatment. The parameters affecting colour were assessed and optimized. Studies were conducted by visible spectrophotometry and digital image acquisition, respectively. The response of the optimized probe towards the concentration of CPZ was tested for several mathematical transformations of the colour coordinates, and a linear relation was found for the sum of hue and luminosity. The limit of detection is 50 μM (corresponding to about 16 μg per mL). The probe enables quick screening for CPZ in real water samples with prior sample treatment.}, keywords = {}, pubstate = {published}, tppubtype = {article} } We are presenting a simple, low-cost and rapid solid-state optical probe for screening chlorpromazine (CPZ) in aquacultures. The method exploits the colourimetric reaction between CPZ and Fe(III) ion that occurs at a solid/liquid interface, the solid layer consisting of ferric iron entrapped in a layer of plasticized PVC. If solutions containing CPZ are dropped onto such a layer, a colour change occurs from light yellow to dark pink or even light blue, depending on the concentration of CPZ. Visual inspection enables the concentration of CPZ to be estimated. The resulting colouration was also monitored by digital image collection for a more accurate quantification. The three coordinates of the hue, saturation and lightness system were obtained by standard image processing along with mathematical data treatment. The parameters affecting colour were assessed and optimized. Studies were conducted by visible spectrophotometry and digital image acquisition, respectively. The response of the optimized probe towards the concentration of CPZ was tested for several mathematical transformations of the colour coordinates, and a linear relation was found for the sum of hue and luminosity. The limit of detection is 50 μM (corresponding to about 16 μg per mL). The probe enables quick screening for CPZ in real water samples with prior sample treatment. |
SAA Almeida, LR Amorim, AM Heitor, MCBSM Montenegro, J Barbosa, LC Sá, MGF Sales Analytical and Bioanalytical Chemistry, 401 (10), pp. 3355-3365, 2011. @article{Almeida2011b, title = {Rapid automated method for on-site determination of sulfadiazine in fish farming: a stainless steel veterinary syringe coated with a selective membrane of PVC serving as a potentiometric detector in a flow-injection-analysis system}, author = {SAA Almeida and LR Amorim and AM Heitor and MCBSM Montenegro and J Barbosa and LC Sá and MGF Sales}, url = {http://link.springer.com/article/10.1007%2Fs00216-011-5441-1 http://recipp.ipp.pt/handle/10400.22/6758}, doi = {10.1007/s00216-011-5441-1}, year = {2011}, date = {2011-12-01}, journal = {Analytical and Bioanalytical Chemistry}, volume = {401}, number = {10}, pages = {3355-3365}, abstract = {Sulfadiazine is an antibiotic of the sulfonamide group and is used as a veterinary drug in fish farming. Monitoring it in the tanks is fundamental to control the applied doses and avoid environmental dissemination. Pursuing this goal, we included a novel potentiometric design in a flow-injection assembly. The electrode body was a stainless steel needle veterinary syringe of 0.8-mm inner diameter. A selective membrane of PVC acted as a sensory surface. Its composition, the length of the electrode, and other flow variables were optimized. The best performance was obtained for sensors of 1.5-cm length and a membrane composition of 33% PVC, 66% o-nitrophenyloctyl ether, 1% ion exchanger, and a small amount of a cationic additive. It exhibited Nernstian slopes of 61.0 mV decade-1 down to 1.0 × 10-5 mol L-1, with a limit of detection of 3.1 × 10-6 mol L-1 in flowing media. All necessary pH/ionic strength adjustments were performed online by merging the sample plug with a buffer carrier of 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid, pH 4.9. The sensor exhibited the advantages of a fast response time (less than 15 s), long operational lifetime (60 days), and good selectivity for chloride, nitrite, acetate, tartrate, citrate, and ascorbate. The flow setup was successfully applied to the analysis of aquaculture waters. The analytical results were validated against those obtained with liquid chromatography–tandem mass spectrometry procedures. The sampling rate was about 84 samples per hour and recoveries ranged from 95.9 to 106.9%.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Sulfadiazine is an antibiotic of the sulfonamide group and is used as a veterinary drug in fish farming. Monitoring it in the tanks is fundamental to control the applied doses and avoid environmental dissemination. Pursuing this goal, we included a novel potentiometric design in a flow-injection assembly. The electrode body was a stainless steel needle veterinary syringe of 0.8-mm inner diameter. A selective membrane of PVC acted as a sensory surface. Its composition, the length of the electrode, and other flow variables were optimized. The best performance was obtained for sensors of 1.5-cm length and a membrane composition of 33% PVC, 66% o-nitrophenyloctyl ether, 1% ion exchanger, and a small amount of a cationic additive. It exhibited Nernstian slopes of 61.0 mV decade-1 down to 1.0 × 10-5 mol L-1, with a limit of detection of 3.1 × 10-6 mol L-1 in flowing media. All necessary pH/ionic strength adjustments were performed online by merging the sample plug with a buffer carrier of 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid, pH 4.9. The sensor exhibited the advantages of a fast response time (less than 15 s), long operational lifetime (60 days), and good selectivity for chloride, nitrite, acetate, tartrate, citrate, and ascorbate. The flow setup was successfully applied to the analysis of aquaculture waters. The analytical results were validated against those obtained with liquid chromatography–tandem mass spectrometry procedures. The sampling rate was about 84 samples per hour and recoveries ranged from 95.9 to 106.9%. |
FTC Moreira, RAF Dutra, JPC Noronha, AL Cunha, MGF Sales Artificial antibodies for troponin T by its imprinting on the surface of multiwalled carbon nanotubes: Its use as sensory surfaces (Journal Article) Biosensors and Bioelectronics, 28 (1), pp. 243-250, 2011. @article{Moreira2011b, title = {Artificial antibodies for troponin T by its imprinting on the surface of multiwalled carbon nanotubes: Its use as sensory surfaces}, author = {FTC Moreira and RAF Dutra and JPC Noronha and AL Cunha and MGF Sales}, url = {http://www.sciencedirect.com/science/article/pii/S0956566311004544 http://recipp.ipp.pt/handle/10400.22/6752 }, doi = {10.1016/j.bios.2011.07.026}, year = {2011}, date = {2011-10-15}, journal = {Biosensors and Bioelectronics}, volume = {28}, number = {1}, pages = {243-250}, abstract = {A novel artificial antibody for troponin T (TnT) was synthesized by molecular imprint (MI) on the surface of multiwalled carbon nanotubes (MWCNT). This was done by attaching TnT to the MWCNT surface, and filling the vacant spaces by polymerizing under mild conditions acrylamide (monomer) in N,N′-methylenebisacrylamide (cross-linker) and ammonium persulphate (initiator). After removing the template, the obtained biomaterial was able to rebind TnT and discriminate it among other interfering species. Stereochemical recognition of TnT was confirmed by the non-rebinding ability displayed by non-imprinted (NI) materials, obtained by imprinting without a template. SEM and FTIR analysis confirmed the surface modification of the MWCNT. The ability of this biomaterial to rebind TnT was confirmed by including it as electroactive compound in a PVC/plasticizer mixture coating a wire of silver, gold or titanium. Anionic slopes of 50 mV decade−1 were obtained for the gold wire coated with MI-based membranes dipped in HEPES buffer of pH 7. The limit of detection was 0.16 μg mL−1. Neither the NI-MWCNT nor the MWCNT showed the ability to recognize the template. Good selectivity was observed against creatinine, sucrose, fructose, myoglobin, sodium glutamate, thiamine and urea. The sensor was tested successfully on serum samples. It is expected that this work opens new horizons on the design of new artificial antibodies for complex protein structures.}, keywords = {}, pubstate = {published}, tppubtype = {article} } A novel artificial antibody for troponin T (TnT) was synthesized by molecular imprint (MI) on the surface of multiwalled carbon nanotubes (MWCNT). This was done by attaching TnT to the MWCNT surface, and filling the vacant spaces by polymerizing under mild conditions acrylamide (monomer) in N,N′-methylenebisacrylamide (cross-linker) and ammonium persulphate (initiator). After removing the template, the obtained biomaterial was able to rebind TnT and discriminate it among other interfering species. Stereochemical recognition of TnT was confirmed by the non-rebinding ability displayed by non-imprinted (NI) materials, obtained by imprinting without a template. SEM and FTIR analysis confirmed the surface modification of the MWCNT. The ability of this biomaterial to rebind TnT was confirmed by including it as electroactive compound in a PVC/plasticizer mixture coating a wire of silver, gold or titanium. Anionic slopes of 50 mV decade−1 were obtained for the gold wire coated with MI-based membranes dipped in HEPES buffer of pH 7. The limit of detection was 0.16 μg mL−1. Neither the NI-MWCNT nor the MWCNT showed the ability to recognize the template. Good selectivity was observed against creatinine, sucrose, fructose, myoglobin, sodium glutamate, thiamine and urea. The sensor was tested successfully on serum samples. It is expected that this work opens new horizons on the design of new artificial antibodies for complex protein structures. |
AH KameL, FTC Moreira, MGF Sales Biomimetic sensor potentiometric system for doxycycline antibiotic using a molecularly imprinted polymer as an artificial recognition element (Journal Article) Sensor Letters, 9 (5), pp. 1654-1660, 2011. @article{Kamel2011, title = {Biomimetic sensor potentiometric system for doxycycline antibiotic using a molecularly imprinted polymer as an artificial recognition element}, author = { AH KameL and FTC Moreira and MGF Sales}, url = {http://www.ingentaconnect.com/content/asp/senlet/2011/00000009/00000005/art00011?token=005a196ddea0693d07e442f2067217d766a445049796c2a406a687627504541676249266d656c8e26a1efe040d http://recipp.ipp.pt/handle/10400.22/6768}, doi = {10.1166/sl.2011.1707}, year = {2011}, date = {2011-10-01}, journal = {Sensor Letters}, volume = {9}, number = {5}, pages = {1654-1660}, abstract = {Molecular imprinting is a useful technique for the preparation of functional materials with molecular recognition properties. A Biomimetic Sensor Potentiometric System was developed for assessment of doxycycline (DOX) antibiotic. The molecularly imprinted polymer (MIP) was synthesized by using doxycycline as a template molecule, methacrylic acid (MAA) and/or acrylamide (AA) as a functional monomer and ethylene glycol dimethacrylat (EGDMA) as a cross-linking agent. The sensing elements were fabricated by the inclusion of DOX imprinted polymers in polyvinyl chloride (PVC) matrix. The sensors showed a high selectivity and a sensitive response to the template in aqueous system. Electrochemical evaluation of these sensors under static (batch) mode of operation reveals near-Nernstian response. MIP/MAA membrane sensor was incorporated in flow-through cells and used as detectors for flow injection analysis (FIA) of DOX. The method has the requisite accuracy, sensitivity and precision to assay DOX in tablets and biological fluids.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Molecular imprinting is a useful technique for the preparation of functional materials with molecular recognition properties. A Biomimetic Sensor Potentiometric System was developed for assessment of doxycycline (DOX) antibiotic. The molecularly imprinted polymer (MIP) was synthesized by using doxycycline as a template molecule, methacrylic acid (MAA) and/or acrylamide (AA) as a functional monomer and ethylene glycol dimethacrylat (EGDMA) as a cross-linking agent. The sensing elements were fabricated by the inclusion of DOX imprinted polymers in polyvinyl chloride (PVC) matrix. The sensors showed a high selectivity and a sensitive response to the template in aqueous system. Electrochemical evaluation of these sensors under static (batch) mode of operation reveals near-Nernstian response. MIP/MAA membrane sensor was incorporated in flow-through cells and used as detectors for flow injection analysis (FIA) of DOX. The method has the requisite accuracy, sensitivity and precision to assay DOX in tablets and biological fluids. |
SAA Almeida, AM Heitor, MCBSM Montenegro, MGF Sales Sulfadiazine-selective determination in aquaculture environment: Selective potentiometric transduction by neutral or charged ionophores (Journal Article) Talanta, 85 (3), pp. 1508-1516, 2011. @article{Almeida2011, title = {Sulfadiazine-selective determination in aquaculture environment: Selective potentiometric transduction by neutral or charged ionophores}, author = {SAA Almeida and AM Heitor and MCBSM Montenegro and MGF Sales }, url = {http://www.sciencedirect.com/science/article/pii/S0039914011005078 http://recipp.ipp.pt/handle/10400.22/6761}, doi = {10.1016/j.talanta.2011.06.022}, year = {2011}, date = {2011-09-15}, journal = {Talanta}, volume = {85}, number = {3}, pages = {1508-1516}, abstract = {Solid-contact sensors for the selective screening of sulfadiazine (SDZ) in aquaculture waters are reported. Sensor surfaces were made from PVC membranes doped with tetraphenylporphyrin-manganese(III) chloride, α-cyclodextrin, β-cyclodextrin, or γ-cyclodextrin ionophores that were dispersed in plasticizer. Some membranes also presented a positive or a negatively charged additive. Phorphyrin-based sensors relied on a charged carrier mechanism. They exhibited a near-Nernstian response with slopes of 52 mV decade−1 and detection limits of 3.91 × 10−5 mol L−1. The addition of cationic lipophilic compounds to the membrane originated Nernstian behaviours, with slopes ranging 59.7–62.0 mV decade−1 and wider linear ranges. Cyclodextrin-based sensors acted as neutral carriers. In general, sensors with positively charged additives showed an improved potentiometric performance when compared to those without additive. Some SDZ selective membranes displayed higher slopes and extended linear concentration ranges with an increasing amount of additive (always <100% ionophore). The sensors were independent from the pH of test solutions within 2–7. The sensors displayed fast response, always <15 s. In general, a good discriminating ability was found in real sample environment. The sensors were successfully applied to the fast screening of SDZ in real waters samples from aquaculture fish farms. The method offered the advantages of simplicity, accuracy, and automation feasibility. The sensing membrane may contribute to the development of small devices allowing in locus measurements of sulfadiazine or parent-drugs.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Solid-contact sensors for the selective screening of sulfadiazine (SDZ) in aquaculture waters are reported. Sensor surfaces were made from PVC membranes doped with tetraphenylporphyrin-manganese(III) chloride, α-cyclodextrin, β-cyclodextrin, or γ-cyclodextrin ionophores that were dispersed in plasticizer. Some membranes also presented a positive or a negatively charged additive. Phorphyrin-based sensors relied on a charged carrier mechanism. They exhibited a near-Nernstian response with slopes of 52 mV decade−1 and detection limits of 3.91 × 10−5 mol L−1. The addition of cationic lipophilic compounds to the membrane originated Nernstian behaviours, with slopes ranging 59.7–62.0 mV decade−1 and wider linear ranges. Cyclodextrin-based sensors acted as neutral carriers. In general, sensors with positively charged additives showed an improved potentiometric performance when compared to those without additive. Some SDZ selective membranes displayed higher slopes and extended linear concentration ranges with an increasing amount of additive (always <100% ionophore). The sensors were independent from the pH of test solutions within 2–7. The sensors displayed fast response, always <15 s. In general, a good discriminating ability was found in real sample environment. The sensors were successfully applied to the fast screening of SDZ in real waters samples from aquaculture fish farms. The method offered the advantages of simplicity, accuracy, and automation feasibility. The sensing membrane may contribute to the development of small devices allowing in locus measurements of sulfadiazine or parent-drugs. |
FTC Moreira, RAF Dutra, JPC Noronha, MGF Sales Biosensors and Bioelectronics, 26 (12), pp. 4760-4766, 2011. @article{Moreira2011b, title = {Myoglobin-biomimetic electroactive materials made by surface molecular imprinting on silica beads and their use as ionophores in polymeric membranes for potentiometric transduction}, author = {FTC Moreira and RAF Dutra and JPC Noronha and MGF Sales}, url = {http://www.sciencedirect.com/science/article/pii/S0956566311003423 http://recipp.ipp.pt/handle/10400.22/6753}, doi = {10.1016/j.bios.2011.05.045}, year = {2011}, date = {2011-08-15}, journal = {Biosensors and Bioelectronics}, volume = {26}, number = {12}, pages = {4760-4766}, abstract = {Myoglobin (Mb) is among the cardiac biomarkers playing a major role in urgent diagnosis of cardiovascular diseases. Its monitoring in point-of-care is therefore fundamental. Pursuing this goal, a novel biomimetic ionophore for the potentiometric transduction of Mb is presented. It was synthesized by surface molecular imprinting (SMI) with the purpose of developing highly efficient sensor layers for near-stereochemical recognition of Mb. The template (Mb) was imprinted on a silane surface that was covalently attached to silica beads by means of self-assembled monolayers. First the silica was modified with an external layer of aldehyde groups. Then, Mb was attached by reaction with its amine groups (on the external surface) and subsequent formation of imine bonds. The vacant places surrounding Mb were filled by polymerization of the silane monomers 3-aminopropyltrimethoxysilane (APTMS) and propyltrimethoxysilane (PTMS). Finally, the template was removed by imine cleavage after treatment with oxalic acid. The results materials were finely dispersed in plasticized PVC selective membranes and used as ionophores in potentiometric transduction. The best analytical features were found in HEPES buffer of pH 4. Under this condition, the limits of detection were of 1.3 × 10−6 mol/L for a linear response after 8.0 × 10−7 mol/L with an anionic slope of −65.9 mV/decade. The imprinting effect was tested by preparing non-imprinted (NI) particles and employing these materials as ionophores. The resulting membranes showed no ability to detect Mb. Good selectivity was observed towards creatinine, sacarose, fructose, galactose, sodium glutamate, and alanine. The analytical application was conducted successfully and showed accurate and precise results.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Myoglobin (Mb) is among the cardiac biomarkers playing a major role in urgent diagnosis of cardiovascular diseases. Its monitoring in point-of-care is therefore fundamental. Pursuing this goal, a novel biomimetic ionophore for the potentiometric transduction of Mb is presented. It was synthesized by surface molecular imprinting (SMI) with the purpose of developing highly efficient sensor layers for near-stereochemical recognition of Mb. The template (Mb) was imprinted on a silane surface that was covalently attached to silica beads by means of self-assembled monolayers. First the silica was modified with an external layer of aldehyde groups. Then, Mb was attached by reaction with its amine groups (on the external surface) and subsequent formation of imine bonds. The vacant places surrounding Mb were filled by polymerization of the silane monomers 3-aminopropyltrimethoxysilane (APTMS) and propyltrimethoxysilane (PTMS). Finally, the template was removed by imine cleavage after treatment with oxalic acid. The results materials were finely dispersed in plasticized PVC selective membranes and used as ionophores in potentiometric transduction. The best analytical features were found in HEPES buffer of pH 4. Under this condition, the limits of detection were of 1.3 × 10−6 mol/L for a linear response after 8.0 × 10−7 mol/L with an anionic slope of −65.9 mV/decade. The imprinting effect was tested by preparing non-imprinted (NI) particles and employing these materials as ionophores. The resulting membranes showed no ability to detect Mb. Good selectivity was observed towards creatinine, sacarose, fructose, galactose, sodium glutamate, and alanine. The analytical application was conducted successfully and showed accurate and precise results. |
AH Kamel, FTC Moreira, TSCR Rebelo, MGF Sales Molecularly-imprinted materials for potentiometric transduction: Application to the antibiotic enrofloxacin (Journal Article) Analytical Letters, 44 (12), pp. 2107-2123, 2011. @article{Kamel2011b, title = {Molecularly-imprinted materials for potentiometric transduction: Application to the antibiotic enrofloxacin}, author = {AH Kamel and FTC Moreira and TSCR Rebelo and MGF Sales}, url = {http://www.tandfonline.com/doi/abs/10.1080/00032719.2010.546021 http://recipp.ipp.pt/handle/10400.22/6765}, doi = {10.1080/00032719.2010.546021}, year = {2011}, date = {2011-08-12}, journal = { Analytical Letters}, volume = {44}, number = {12}, pages = {2107-2123}, abstract = {Enrofloxacin (ENR) is an antimicrobial used both in humans and in food producing species. Its control is required in farmed species and their surroundings in order to reduce the prevalence of antibiotic resistant bacteria. Thus, a new biomimetic sensor enrofloxacin is presented. An artificial host was imprinted in specific polymers. These were dispersed in 2-nitrophenyloctyl ether and entrapped in a poly(vinyl chloride) matrix. The potentiometric sensors exhibited a near-Nernstian response. Slopes expressing mV/Δlog([ENR]/M) varied within 48–63. The detection limits ranged from 0.28 to 1.01 µg mL−1. Sensors were independent from the pH of test solutions within 4–7. Good selectivity was observed toward potassium, calcium, barium, magnesium, glycine, ascorbic acid, creatinine, norfloxacin, ciprofloxacin, and tetracycline. In flowing media, the biomimetic sensors presented good reproducibility (RSD of ± 0.7%), fast response, good sensitivity (47 mV/Δlog([ENR]/M), wide linear range (1.0 × 10−5–1.0 × 10−3 M), low detection limit (0.9 µg mL−1), and a stable baseline for a 5 × 10−2 M acetate buffer (pH 4.7) carrier. The sensors were used to analyze fish samples. The method offered the advantages of simplicity, accuracy, and automation feasibility. The sensing membrane may contribute to the development of small devices allowing in vivo measurements of enrofloxacin or parent-drugs.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Enrofloxacin (ENR) is an antimicrobial used both in humans and in food producing species. Its control is required in farmed species and their surroundings in order to reduce the prevalence of antibiotic resistant bacteria. Thus, a new biomimetic sensor enrofloxacin is presented. An artificial host was imprinted in specific polymers. These were dispersed in 2-nitrophenyloctyl ether and entrapped in a poly(vinyl chloride) matrix. The potentiometric sensors exhibited a near-Nernstian response. Slopes expressing mV/Δlog([ENR]/M) varied within 48–63. The detection limits ranged from 0.28 to 1.01 µg mL−1. Sensors were independent from the pH of test solutions within 4–7. Good selectivity was observed toward potassium, calcium, barium, magnesium, glycine, ascorbic acid, creatinine, norfloxacin, ciprofloxacin, and tetracycline. In flowing media, the biomimetic sensors presented good reproducibility (RSD of ± 0.7%), fast response, good sensitivity (47 mV/Δlog([ENR]/M), wide linear range (1.0 × 10−5–1.0 × 10−3 M), low detection limit (0.9 µg mL−1), and a stable baseline for a 5 × 10−2 M acetate buffer (pH 4.7) carrier. The sensors were used to analyze fish samples. The method offered the advantages of simplicity, accuracy, and automation feasibility. The sensing membrane may contribute to the development of small devices allowing in vivo measurements of enrofloxacin or parent-drugs. |
FTC Moreira, MGF Sales Biomimetic sensors of molecularly-imprinted polymers for chlorpromazine determination (Journal Article) Materials Science and Engineering: C, 31 (5), pp. 1121-1128, 2011. @article{Moreira2011b, title = {Biomimetic sensors of molecularly-imprinted polymers for chlorpromazine determination}, author = {FTC Moreira and MGF Sales }, url = {http://www.sciencedirect.com/science/article/pii/S0928493111001172 http://recipp.ipp.pt/handle/10400.22/6762}, doi = {10.1016/j.msec.2011.04.012}, year = {2011}, date = {2011-07-20}, journal = {Materials Science and Engineering: C}, volume = {31}, number = {5}, pages = {1121-1128}, abstract = {A new man-tailored biomimetic sensor for Chlorpromazine host-guest interactions and potentiometric transduction is presented. The artificial host was imprinted within methacrylic acid, 2-vinyl pyridine and 2-acrylamido-2-methyl-1-propanesulfonic acid based polymers. Molecularly imprinted particles were dispersed in 2-nitrophenyloctyl ether and entrapped in a poly(vinyl chloride) matrix. Slopes and detection limits ranged 51–67 mV/decade and 0.46–3.9 μg/mL, respectively, in steady state conditions. Sensors were independent from the pH of test solutions within 2.0–5.5. Good selectivity was observed towards oxytetracycline, doxytetracycline, ciprofloxacin, enrofloxacin, nalidixic acid, sulfadiazine, trimethoprim, glycine, hydroxylamine, cysteine and creatinine. Analytical features in flowing media were evaluated on a double-channel manifold, with a carrier solution of 5.0 × 10−2 mol/L phosphate buffer. Near-Nernstian response was observed over the concentration range 1.0 × 10−4 to 1.0 × 10−2 mol/L. Average slopes were about 48 mV/decade. The sensors were successfully applied to field monitoring of CPZ in fish samples, offering the advantages of simplicity, accuracy, automation feasibility and applicability to complex samples.}, keywords = {}, pubstate = {published}, tppubtype = {article} } A new man-tailored biomimetic sensor for Chlorpromazine host-guest interactions and potentiometric transduction is presented. The artificial host was imprinted within methacrylic acid, 2-vinyl pyridine and 2-acrylamido-2-methyl-1-propanesulfonic acid based polymers. Molecularly imprinted particles were dispersed in 2-nitrophenyloctyl ether and entrapped in a poly(vinyl chloride) matrix. Slopes and detection limits ranged 51–67 mV/decade and 0.46–3.9 μg/mL, respectively, in steady state conditions. Sensors were independent from the pH of test solutions within 2.0–5.5. Good selectivity was observed towards oxytetracycline, doxytetracycline, ciprofloxacin, enrofloxacin, nalidixic acid, sulfadiazine, trimethoprim, glycine, hydroxylamine, cysteine and creatinine. Analytical features in flowing media were evaluated on a double-channel manifold, with a carrier solution of 5.0 × 10−2 mol/L phosphate buffer. Near-Nernstian response was observed over the concentration range 1.0 × 10−4 to 1.0 × 10−2 mol/L. Average slopes were about 48 mV/decade. The sensors were successfully applied to field monitoring of CPZ in fish samples, offering the advantages of simplicity, accuracy, automation feasibility and applicability to complex samples. |
RB Queirós, SO Silva, JPC Noronha, O Frazão, P Jorge, GG Aguilar, PVS Marques, MGF Sales Microcystin-LR detection in water by the Fabry–Pérot interferometer using an optical fibre coated with a sol–gel imprinted sensing membrane (Journal Article) Biosensors and Bioelectronics, 26 (9), pp. 3932-3937, 2011. @article{Queirós2011, title = {Microcystin-LR detection in water by the Fabry–Pérot interferometer using an optical fibre coated with a sol–gel imprinted sensing membrane}, author = {RB Queirós and SO Silva and JPC Noronha and O Frazão and P Jorge and GG Aguilar and PVS Marques and MGF Sales }, url = {http://www.sciencedirect.com/science/article/pii/S0956566311001710 http://recipp.ipp.pt/handle/10400.22/6754}, doi = {10.1016/j.bios.2011.03.015}, year = {2011}, date = {2011-05-15}, journal = {Biosensors and Bioelectronics}, volume = {26}, number = {9}, pages = {3932-3937}, abstract = {Cyanobacteria deteriorate the water quality and are responsible for emerging outbreaks and epidemics causing harmful diseases in Humans and animals because of their toxins. Microcystin-LR (MCT) is one of the most relevant cyanotoxin, being the most widely studied hepatotoxin. For safety purposes, the World Health Organization recommends a maximum value of 1 μg L−1 of MCT in drinking water. Therefore, there is a great demand for remote and real-time sensing techniques to detect and quantify MCT. In this work a Fabry–Pérot sensing probe based on an optical fibre tip coated with a MCT selective thin film is presented. The membranes were developed by imprinting MCT in a sol–gel matrix that was applied over the tip of the fibre by dip coating. The imprinting effect was obtained by curing the sol–gel membrane, prepared with (3-aminopropyl) trimethoxysilane (APTMS), diphenyl-dimethoxysilane (DPDMS), tetraethoxysilane (TEOS), in the presence of MCT. The imprinting effect was tested by preparing a similar membrane without template. In general, the fibre Fabry–Pérot with a Molecular Imprinted Polymer (MIP) sensor showed low thermal effect, thus avoiding the need of temperature control in field applications. It presented a linear response to MCT concentration within 0.3–1.4 μg L−1 with a sensitivity of −12.4 ± 0.7 nm L μg−1. The corresponding Non-Imprinted Polymer (NIP) displayed linear behaviour for the same MCT concentration range, but with much less sensitivity, of −5.9 ± 0.2 nm L μg−1. The method shows excellent selectivity for MCT against other species co-existing with the analyte in environmental waters. It was successfully applied to the determination of MCT in contaminated samples. The main advantages of the proposed optical sensor include high sensitivity and specificity, low-cost, robustness, easy preparation and preservation.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Cyanobacteria deteriorate the water quality and are responsible for emerging outbreaks and epidemics causing harmful diseases in Humans and animals because of their toxins. Microcystin-LR (MCT) is one of the most relevant cyanotoxin, being the most widely studied hepatotoxin. For safety purposes, the World Health Organization recommends a maximum value of 1 μg L−1 of MCT in drinking water. Therefore, there is a great demand for remote and real-time sensing techniques to detect and quantify MCT. In this work a Fabry–Pérot sensing probe based on an optical fibre tip coated with a MCT selective thin film is presented. The membranes were developed by imprinting MCT in a sol–gel matrix that was applied over the tip of the fibre by dip coating. The imprinting effect was obtained by curing the sol–gel membrane, prepared with (3-aminopropyl) trimethoxysilane (APTMS), diphenyl-dimethoxysilane (DPDMS), tetraethoxysilane (TEOS), in the presence of MCT. The imprinting effect was tested by preparing a similar membrane without template. In general, the fibre Fabry–Pérot with a Molecular Imprinted Polymer (MIP) sensor showed low thermal effect, thus avoiding the need of temperature control in field applications. It presented a linear response to MCT concentration within 0.3–1.4 μg L−1 with a sensitivity of −12.4 ± 0.7 nm L μg−1. The corresponding Non-Imprinted Polymer (NIP) displayed linear behaviour for the same MCT concentration range, but with much less sensitivity, of −5.9 ± 0.2 nm L μg−1. The method shows excellent selectivity for MCT against other species co-existing with the analyte in environmental waters. It was successfully applied to the determination of MCT in contaminated samples. The main advantages of the proposed optical sensor include high sensitivity and specificity, low-cost, robustness, easy preparation and preservation. |
TSCR Rebelo, SAA Almeida, JRL Guerreiro, MCBSM Montenegro, MGF Sales Trimethoprim-selective electrodes with molecularly imprinted polymers acting as ionophores and potentiometric transduction on graphite solid-contact (Journal Article) Microchemical Journal, 98 (1), pp. 21-28, 2011. @article{Rebelo2011, title = {Trimethoprim-selective electrodes with molecularly imprinted polymers acting as ionophores and potentiometric transduction on graphite solid-contact}, author = {TSCR Rebelo and SAA Almeida and JRL Guerreiro and MCBSM Montenegro and MGF Sales}, url = {http://www.sciencedirect.com/science/article/pii/S0026265X10002122 http://recipp.ipp.pt/handle/10400.22/6766}, doi = {10.1016/j.microc.2010.10.006}, year = {2011}, date = {2011-05-01}, journal = {Microchemical Journal}, volume = {98}, number = {1}, pages = {21-28}, abstract = {This work proposes a new biomimetic sensor material for trimethoprim. It is prepared by means of radical polymerization, having trimethylolpropane trimethacrylate as cross-linker, benzoyl peroxide as radicalar iniciator, chloroform as porogenic solvent, and methacrylic acid and 2-vinyl pyridine as monomers. Different percentages of sensor in a range between 1 and 6% were studied. Their behavior was compared to that obtained with ion-exchanger quaternary ammonium salt (additive tetrakis(p-chlorophenyl)borate or tetraphenylborate). The effect of an anionic additive in the sensing membrane was also tested. Trimethoprim sensors with 1% of imprinted particles from methacrylic acid monomers showed the best response in terms of slope (59.7 mV/decade) and detection limit (4.01 × 10− 7 mol/L). These electrodes displayed also a good selectivity towards nickel, manganese aluminium, ammonium, lead, potassium, sodium, iron, chromium, sulfadiazine, alanine, cysteine, tryptophan, valine and glycine. The sensors were not affected by pH changes from 2 to 6. They were successfully applied to the analysis of water from aquaculture.}, keywords = {}, pubstate = {published}, tppubtype = {article} } This work proposes a new biomimetic sensor material for trimethoprim. It is prepared by means of radical polymerization, having trimethylolpropane trimethacrylate as cross-linker, benzoyl peroxide as radicalar iniciator, chloroform as porogenic solvent, and methacrylic acid and 2-vinyl pyridine as monomers. Different percentages of sensor in a range between 1 and 6% were studied. Their behavior was compared to that obtained with ion-exchanger quaternary ammonium salt (additive tetrakis(p-chlorophenyl)borate or tetraphenylborate). The effect of an anionic additive in the sensing membrane was also tested. Trimethoprim sensors with 1% of imprinted particles from methacrylic acid monomers showed the best response in terms of slope (59.7 mV/decade) and detection limit (4.01 × 10− 7 mol/L). These electrodes displayed also a good selectivity towards nickel, manganese aluminium, ammonium, lead, potassium, sodium, iron, chromium, sulfadiazine, alanine, cysteine, tryptophan, valine and glycine. The sensors were not affected by pH changes from 2 to 6. They were successfully applied to the analysis of water from aquaculture. |
JRL Guerreiro, VAP Freitas, MGF Sales New sensing materials of molecularly-imprinted polymers for the selective recognition of Chlortetracycline (Journal Article) Microchemical Journal, 97 (2), pp. 173-181, 2011. @article{Guerreiro2011b, title = {New sensing materials of molecularly-imprinted polymers for the selective recognition of Chlortetracycline}, author = {JRL Guerreiro and VAP Freitas and MGF Sales }, url = {http://www.sciencedirect.com/science/article/pii/S0026265X1000161X http://recipp.ipp.pt/handle/10400.22/6767}, doi = {10.1016/j.microc.2010.08.011}, year = {2011}, date = {2011-03-01}, journal = {Microchemical Journal}, volume = {97}, number = {2}, pages = {173-181}, abstract = {As a result of the stressful conditions in aquaculture facilities there is a high risk of bacterial infections among cultured fish. Chlortetracycline (CTC) is one of the antimicrobials used to solve this problem. It is a broad spectrum antibacterial active against a wide range of Gram-positive and Gram-negative bacteria. Numerous analytical methods for screening, identifying, and quantifying CTC in animal products have been developed over the years. An alternative and advantageous method should rely on expeditious and efficient procedures providing highly specific and sensitive measurements in food samples. Ion-selective electrodes (ISEs) could meet these criteria. The only ISE reported in literature for this purpose used traditional electro-active materials. A selectivity enhancement could however be achieved after improving the analyte recognition by molecularly imprinted polymers (MIPs). Several MIP particles were synthesized and used as electro-active materials. ISEs based in methacrylic acid monomers showed the best analytical performance according to slope (62.5 and 68.6 mV/decade) and detection limit (4.1 × 10−5 and 5.5 × 10−5 mol L−1). The electrodes displayed good selectivity. The ISEs are not affected by pH changes ranging from 2.5 to 13. The sensors were successfully applied to the analysis of serum, urine and fish samples.}, keywords = {}, pubstate = {published}, tppubtype = {article} } As a result of the stressful conditions in aquaculture facilities there is a high risk of bacterial infections among cultured fish. Chlortetracycline (CTC) is one of the antimicrobials used to solve this problem. It is a broad spectrum antibacterial active against a wide range of Gram-positive and Gram-negative bacteria. Numerous analytical methods for screening, identifying, and quantifying CTC in animal products have been developed over the years. An alternative and advantageous method should rely on expeditious and efficient procedures providing highly specific and sensitive measurements in food samples. Ion-selective electrodes (ISEs) could meet these criteria. The only ISE reported in literature for this purpose used traditional electro-active materials. A selectivity enhancement could however be achieved after improving the analyte recognition by molecularly imprinted polymers (MIPs). Several MIP particles were synthesized and used as electro-active materials. ISEs based in methacrylic acid monomers showed the best analytical performance according to slope (62.5 and 68.6 mV/decade) and detection limit (4.1 × 10−5 and 5.5 × 10−5 mol L−1). The electrodes displayed good selectivity. The ISEs are not affected by pH changes ranging from 2.5 to 13. The sensors were successfully applied to the analysis of serum, urine and fish samples. |
FTC Moreira, VAP Freitas, MGF Sales Biomimetic norfloxacin sensors made of molecularly-imprinted materials for potentiometric transduction (Journal Article) Microchimica Acta, 172 (1), pp. 15-23, 2011. @article{Moreira2011, title = {Biomimetic norfloxacin sensors made of molecularly-imprinted materials for potentiometric transduction}, author = {FTC Moreira and VAP Freitas and MGF Sales}, url = {http://link.springer.com/article/10.1007%2Fs00604-010-0464-4 http://recipp.ipp.pt/handle/10400.22/6764}, doi = {10.1007/s00604-010-0464-4}, year = {2011}, date = {2011-02-01}, journal = {Microchimica Acta}, volume = {172}, number = {1}, pages = {15-23}, abstract = {A biomimetic sensor for norfloxacin is presented that is based on host-guest interactions and potentiometric transduction. The artificial host was imprinted into polymers made from methacrylic acid and/or 2-vinyl pyridine. The resulting particles were entrapped in a plasticized poly(vinyl chloride) (PVC) matrix. The sensors exhibit near-Nernstian response in steady state evaluations, and detection limits range from 0.40 to 1.0 μg mL−1, respectively, and are independent of pH values at between 2 and 6, and 8 and 11, respectively. Good selectivity was observed over several potential interferents. In flowing media, the sensors exhibit fast response, a sensitivity of 68.2 mV per decade, a linear range from 79 μM to 2.5 mM, a detection limit of 20 μg mL−1, and a stable baseline. The sensors were successfully applied to field monitoring of norfloxacin in fish samples, biological samples, and pharmaceutical products.}, keywords = {}, pubstate = {published}, tppubtype = {article} } A biomimetic sensor for norfloxacin is presented that is based on host-guest interactions and potentiometric transduction. The artificial host was imprinted into polymers made from methacrylic acid and/or 2-vinyl pyridine. The resulting particles were entrapped in a plasticized poly(vinyl chloride) (PVC) matrix. The sensors exhibit near-Nernstian response in steady state evaluations, and detection limits range from 0.40 to 1.0 μg mL−1, respectively, and are independent of pH values at between 2 and 6, and 8 and 11, respectively. Good selectivity was observed over several potential interferents. In flowing media, the sensors exhibit fast response, a sensitivity of 68.2 mV per decade, a linear range from 79 μM to 2.5 mM, a detection limit of 20 μg mL−1, and a stable baseline. The sensors were successfully applied to field monitoring of norfloxacin in fish samples, biological samples, and pharmaceutical products. |
HMV Oliveira, FTC Moreira, MGF Sales Ciprofloxacin-imprinted polymeric receptors as ionophores for potentiometric transduction (Journal Article) Electrochimica Acta, 56 (5), pp. 2017-2023, 2011. @article{Oliveira2011, title = {Ciprofloxacin-imprinted polymeric receptors as ionophores for potentiometric transduction}, author = {HMV Oliveira and FTC Moreira and MGF Sales}, url = {http://www.sciencedirect.com/science/article/pii/S001346861001594X http://recipp.ipp.pt/handle/10400.22/6763}, doi = {10.1016/j.electacta.2010.11.082}, year = {2011}, date = {2011-02-01}, journal = {Electrochimica Acta}, volume = {56}, number = {5}, pages = {2017-2023}, abstract = {A 3D-mirror synthetic receptor for ciprofloxacin host–guest interactions and potentiometric transduction is presented. The host cavity was shaped on a polymeric surface assembled with methacrylic acid or 2-vinyl pyridine monomers by radical polymerization. Molecularly imprinted particles were dispersed in 2-nitrophenyl octyl ether and entrapped in a poly(vinyl chloride) matrix. The sensors exhibited a near-Nernstian response in steady state evaluations. Slopes and detection limits ranged from 26.8 to 50.0 mV decade−1 and 1.0 × 10−5 to 2.7 × 10−5 mol L−1, respectively. Good selectivity was observed for trimethoprim, enrofloxacin, tetracycline, cysteine, galactose, hydroxylamine, creatinine, ammonium chloride, sucrose, glucose, sulphamerazine and sulfadiazine. The sensors were successfully applied to the determination of ciprofloxacin concentrations in fish and in pharmaceuticals. The method presented offered the advantages of simplicity, accuracy, applicability to colored and turbid samples and automation feasibility, as well as confirming the use of molecularly imprinted polymers as ionophores for organic ion recognition in potentiometric transduction.}, keywords = {}, pubstate = {published}, tppubtype = {article} } A 3D-mirror synthetic receptor for ciprofloxacin host–guest interactions and potentiometric transduction is presented. The host cavity was shaped on a polymeric surface assembled with methacrylic acid or 2-vinyl pyridine monomers by radical polymerization. Molecularly imprinted particles were dispersed in 2-nitrophenyl octyl ether and entrapped in a poly(vinyl chloride) matrix. The sensors exhibited a near-Nernstian response in steady state evaluations. Slopes and detection limits ranged from 26.8 to 50.0 mV decade−1 and 1.0 × 10−5 to 2.7 × 10−5 mol L−1, respectively. Good selectivity was observed for trimethoprim, enrofloxacin, tetracycline, cysteine, galactose, hydroxylamine, creatinine, ammonium chloride, sucrose, glucose, sulphamerazine and sulfadiazine. The sensors were successfully applied to the determination of ciprofloxacin concentrations in fish and in pharmaceuticals. The method presented offered the advantages of simplicity, accuracy, applicability to colored and turbid samples and automation feasibility, as well as confirming the use of molecularly imprinted polymers as ionophores for organic ion recognition in potentiometric transduction. |
JRL Guerreiro, FTC Moreira, TSCR Rebelo, MGF Sales Selective recognition in potentiometric transduction of amoxicillin by molecularly-imprinted materials (Journal Article) European Food Research and Technology, 232 (1), pp. 39-50, 2011. @article{Guerreiro2011, title = {Selective recognition in potentiometric transduction of amoxicillin by molecularly-imprinted materials}, author = {JRL Guerreiro and FTC Moreira and TSCR Rebelo and MGF Sales}, url = {http://link.springer.com/article/10.1007/s00217-010-1360-1/fulltext.html http://recipp.ipp.pt/handle/10400.22/6769}, doi = {10.1007/s00217-010-1360-1}, year = {2011}, date = {2011-01-01}, journal = {European Food Research and Technology}, volume = {232}, number = {1}, pages = {39-50}, abstract = {The indiscriminate use of antibiotics in food-producing animals has received increasing attention as a contributory factor in the international emergence of antibiotic-resistant bacteria (Woodward in Pesticide, veterinary and other residues in food, CRC Press, Boca Raton, 2004). Numerous analytical methods for quantifying antibacterial residues in edible animal products have been developed over years (Woodward in Pesticide, veterinary and other residues in food, CRC Press, Boca Raton, 2004; Botsoglou and Fletouris in Handbook of food analysis, residues and other food component analysis, Marcel Dekker, Ghent, 2004). Being Amoxicillin (AMOX) one of those critical veterinary drugs, efforts have been made to develop simple and expeditious methods for its control in food samples. In literature, only one AMOX-selective electrode has been reported so far. In that work, phosphotungstate:amoxycillinium ion exchanger was used as electroactive material (Shoukry et al. in Electroanalysis 6:914–917, 1994). Designing new materials based on molecularly imprinted polymers (MIPs) which are complementary to the size and charge of AMOX could lead to very selective interactions, thus enhancing the selectivity of the sensing unit. AMOX-selective electrodes used imprinted polymers as electroactive materials having AMOX as target molecule to design a biomimetic imprinted cavity. Poly(vinyl chloride), sensors of methacrylic acid displayed Nernstian slopes (60.7 mV/decade) and low detection limits (2.9 × 10−5 mol/L). The potentiometric responses were not affected by pH within 4–5 and showed good selectivity. The electrodes were applied successfully to the analysis of real samples.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The indiscriminate use of antibiotics in food-producing animals has received increasing attention as a contributory factor in the international emergence of antibiotic-resistant bacteria (Woodward in Pesticide, veterinary and other residues in food, CRC Press, Boca Raton, 2004). Numerous analytical methods for quantifying antibacterial residues in edible animal products have been developed over years (Woodward in Pesticide, veterinary and other residues in food, CRC Press, Boca Raton, 2004; Botsoglou and Fletouris in Handbook of food analysis, residues and other food component analysis, Marcel Dekker, Ghent, 2004). Being Amoxicillin (AMOX) one of those critical veterinary drugs, efforts have been made to develop simple and expeditious methods for its control in food samples. In literature, only one AMOX-selective electrode has been reported so far. In that work, phosphotungstate:amoxycillinium ion exchanger was used as electroactive material (Shoukry et al. in Electroanalysis 6:914–917, 1994). Designing new materials based on molecularly imprinted polymers (MIPs) which are complementary to the size and charge of AMOX could lead to very selective interactions, thus enhancing the selectivity of the sensing unit. AMOX-selective electrodes used imprinted polymers as electroactive materials having AMOX as target molecule to design a biomimetic imprinted cavity. Poly(vinyl chloride), sensors of methacrylic acid displayed Nernstian slopes (60.7 mV/decade) and low detection limits (2.9 × 10−5 mol/L). The potentiometric responses were not affected by pH within 4–5 and showed good selectivity. The electrodes were applied successfully to the analysis of real samples. |
CAPÍTULOS DE LIVROS
2020
2019
2018
2017
MF Frasco, LAANA Truta, MGF Sales, FTC Moreira Imprinting technology in electrochemical biomimetic sensors (Book) MDPI, Basel, Switzerland, Sensors (Basel), Vol 17(3), page 523, 2017. @book{Frasco2017, title = {Imprinting technology in electrochemical biomimetic sensors}, author = {MF Frasco and LAANA Truta and MGF Sales and FTC Moreira}, editor = {Bo Mattiasson and Gizem Ertürk}, url = {https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5375809/}, doi = {10.3390/s17030523}, year = {2017}, date = {2017-03-06}, publisher = {MDPI, Basel, Switzerland}, address = {Sensors (Basel), Vol 17(3), page 523}, series = {Sensors (Basel)}, abstract = {Biosensors are a promising tool offering the possibility of low cost and fast analytical screening in point-of-care diagnostics and for on-site detection in the field. Most biosensors in routine use ensure their selectivity/specificity by including natural receptors as biorecognition element. These materials are however too expensive and hard to obtain for every biochemical molecule of interest in environmental and clinical practice. Molecularly imprinted polymers have emerged through time as an alternative to natural antibodies in biosensors. In theory, these materials are stable and robust, presenting much higher capacity to resist to harsher conditions of pH, temperature, pressure or organic solvents. In addition, these synthetic materials are much cheaper than their natural counterparts while offering equivalent affinity and sensitivity in the molecular recognition of the target analyte. Imprinting technology and biosensors have met quite recently, relying mostly on electrochemical detection and enabling a direct reading of different analytes, while promoting significant advances in various fields of use. Thus, this review encompasses such developments and describes a general overview for building promising biomimetic materials as biorecognition elements in electrochemical sensors. It includes different molecular imprinting strategies such as the choice of polymer material, imprinting methodology and assembly on the transduction platform. Their interface with the most recent nanostructured supports acting as standard conductive materials within electrochemical biomimetic sensors is pointed out.}, keywords = {}, pubstate = {published}, tppubtype = {book} } Biosensors are a promising tool offering the possibility of low cost and fast analytical screening in point-of-care diagnostics and for on-site detection in the field. Most biosensors in routine use ensure their selectivity/specificity by including natural receptors as biorecognition element. These materials are however too expensive and hard to obtain for every biochemical molecule of interest in environmental and clinical practice. Molecularly imprinted polymers have emerged through time as an alternative to natural antibodies in biosensors. In theory, these materials are stable and robust, presenting much higher capacity to resist to harsher conditions of pH, temperature, pressure or organic solvents. In addition, these synthetic materials are much cheaper than their natural counterparts while offering equivalent affinity and sensitivity in the molecular recognition of the target analyte. Imprinting technology and biosensors have met quite recently, relying mostly on electrochemical detection and enabling a direct reading of different analytes, while promoting significant advances in various fields of use. Thus, this review encompasses such developments and describes a general overview for building promising biomimetic materials as biorecognition elements in electrochemical sensors. It includes different molecular imprinting strategies such as the choice of polymer material, imprinting methodology and assembly on the transduction platform. Their interface with the most recent nanostructured supports acting as standard conductive materials within electrochemical biomimetic sensors is pointed out. |
2015
FTC Moreira, JRL Guerreiro, L Brandão, MGF Sales Synthesis of molecular biomimetics (Book) Chapter 1 in Biomimetic Technologies, Principles and Applications, Woodhead Publishing, Series in Electronic and Optical Materials, Pages 3–31, 2015. @book{Moreira2015b, title = {Synthesis of molecular biomimetics}, author = {FTC Moreira and JRL Guerreiro and L Brandão and MGF Sales}, editor = {Trung Dung Ngo}, url = {http://www.sciencedirect.com/science/article/pii/B978008100249000001X http://recipp.ipp.pt/handle/10400.22/7746}, doi = {10.1016/B978-0-08-100249-0.00001-X}, year = {2015}, date = {2015-01-01}, pages = {3-31}, publisher = {Woodhead Publishing}, address = {Series in Electronic and Optical Materials, Pages 3–31}, edition = {Chapter 1 in Biomimetic Technologies, Principles and Applications}, series = {Electronic and Optical Materials}, abstract = {Biomimetics has paved the way toward new materials and technologies inspired in Nature. Biomolecules and their supramolecular organization have today a leading role in biomimetics, benefiting from the recent advances in nanotechnology. The production of biomimetic materials may be however a difficult task, because Nature does it very well. The use of several building blocks assembled in bottom-up arrangement is without doubt at the core of this process. Such building blocks include different molecules or molecular arrangements, of synthetic or natural origin, such as amino acids, lipids, carbohydrates, nucleic acids, carbon allotropes, dendrimers, or organosilanes, among others. The most common approaches to produce synthetic biomimetic materials are reported herein, with special emphasis to building blocks and their supramolecular arrangement.}, keywords = {}, pubstate = {published}, tppubtype = {book} } Biomimetics has paved the way toward new materials and technologies inspired in Nature. Biomolecules and their supramolecular organization have today a leading role in biomimetics, benefiting from the recent advances in nanotechnology. The production of biomimetic materials may be however a difficult task, because Nature does it very well. The use of several building blocks assembled in bottom-up arrangement is without doubt at the core of this process. Such building blocks include different molecules or molecular arrangements, of synthetic or natural origin, such as amino acids, lipids, carbohydrates, nucleic acids, carbon allotropes, dendrimers, or organosilanes, among others. The most common approaches to produce synthetic biomimetic materials are reported herein, with special emphasis to building blocks and their supramolecular arrangement. |
2012
RB Queiros, JPC Noronha, PVS Marques, MGF Sales Ecological Water Quality - Water Treatment and Reuse, Dr. Voudouris (Ed.), InTech, 2012, ISBN: 978-953-51-0508-4. @book{Queiros2012b, title = {Emerging (bio)sensing technology for assessing and monitoring freshwater contamination - Methods and application}, author = {RB Queiros and JPC Noronha and PVS Marques and MGF Sales}, editor = {Kostas Voudouris}, url = {http://www.intechopen.com/books/ecological-water-quality-water-treatment-and-reuse/emerging-bio-sensing-technology-for-assessing-and-monitoring-freshwater-contamination-methods-and-ap}, doi = {10.5772/32198}, isbn = {978-953-51-0508-4}, year = {2012}, date = {2012-05-05}, number = {4}, publisher = {Ecological Water Quality - Water Treatment and Reuse, Dr. Voudouris (Ed.), InTech}, abstract = {Water is life and its preservation is not only a moral obligation but also a legal requirement. By 2030, global demands will exceed more than 40 % the existing resources and more than a third of the world's population will have to deal with water shortages (European Environmental Agency [EEA], 2010). Climate change effects on water resources will not help. Efforts are being made throughout Europe towards a reduced and efficient water use and prevention of any further deterioration of the quality of water (Eurostat, European Comission [EC], 2010). The Water Framework Directive (EC, 2000) lays down provisions for monitoring, assessing and classifying water quality. Supporting this, the Drinking Water sets standards for 48 microbiological and chemical parameters that must be monitored and tested regularly (EC, 1998). The Bathing Water Directive also sets concentration limits for microbiological pollutants in inland and coastal bathing waters (EC, 2006), addressing risks from algae and cyanobacteria contamination and faecal contamination, requiring immediate action, including the provision of information to the public, to prevent exposure. With these directives, among others, the European Union [EU] expects to offer its citizens, by 2015, fresh and coastal waters of good quality.}, keywords = {}, pubstate = {published}, tppubtype = {book} } Water is life and its preservation is not only a moral obligation but also a legal requirement. By 2030, global demands will exceed more than 40 % the existing resources and more than a third of the world's population will have to deal with water shortages (European Environmental Agency [EEA], 2010). Climate change effects on water resources will not help. Efforts are being made throughout Europe towards a reduced and efficient water use and prevention of any further deterioration of the quality of water (Eurostat, European Comission [EC], 2010). The Water Framework Directive (EC, 2000) lays down provisions for monitoring, assessing and classifying water quality. Supporting this, the Drinking Water sets standards for 48 microbiological and chemical parameters that must be monitored and tested regularly (EC, 1998). The Bathing Water Directive also sets concentration limits for microbiological pollutants in inland and coastal bathing waters (EC, 2006), addressing risks from algae and cyanobacteria contamination and faecal contamination, requiring immediate action, including the provision of information to the public, to prevent exposure. With these directives, among others, the European Union [EU] expects to offer its citizens, by 2015, fresh and coastal waters of good quality. |
PARTICIPAÇÕES EM CONFERÊNCIAS
2020
2019
A Marques, N Ferreira, R Martins, C Bodo, MGF Sales, B Costa-Silva, E Fortunato Label-free nanosensing platform for breast cancer exosome profiling (Conference) NanoBio&Med2019 Barcelona, Espanha, 19 a 21 de novembro., 2019. (BibTeX) @conference{Marques2019, title = {Label-free nanosensing platform for breast cancer exosome profiling}, author = {A Marques, N Ferreira, R Martins, C Bodo, MGF Sales, B Costa-Silva, E Fortunato}, year = {2019}, date = {2019-11-19}, address = { Barcelona, Espanha, 19 a 21 de novembro.}, organization = { NanoBio&Med2019}, keywords = {}, pubstate = {published}, tppubtype = {conference} } |
C Hora, F Santos, MGF Sales, D Ivanou, A Mendes, E Dyenamo DSSC Conference, P19, Uppsala, Suécia, 14 a 15 de outubro, 2019. (BibTeX) @conference{Hora2019, title = {Efficient and cheap alternatives to platinum counter electrodes for dye-sensitized solar cells with cobalt(III/II) redox shuttle}, author = {C Hora, F Santos, MGF Sales, D Ivanou, A Mendes, E}, year = {2019}, date = {2019-10-14}, publisher = {Dyenamo DSSC Conference, P19}, address = { Uppsala, Suécia, 14 a 15 de outubro}, keywords = {}, pubstate = {published}, tppubtype = {conference} } |
MGF Sales Dispositivos para a monitorização de biomarcadores em fluídos biológicos (Conference) XI Congresso Nacional da APIH , Albufeira, 12 de outubro., 2019. (BibTeX) @conference{Sales2019, title = {Dispositivos para a monitorização de biomarcadores em fluídos biológicos}, author = {MGF Sales }, year = {2019}, date = {2019-10-12}, publisher = {XI Congresso Nacional da APIH }, address = {Albufeira, 12 de outubro.}, keywords = {}, pubstate = {published}, tppubtype = {conference} } |
MGF Sales New approaches for sensing glycoproteins as disease biomarkers (Conference) apresentação Plenária no 13th International Meeting of the Portuguese Carbohydrate Group, PL3. 2019. (BibTeX) @conference{Sales2019b, title = {New approaches for sensing glycoproteins as disease biomarkers}, author = {MGF Sales}, year = {2019}, date = {2019-09-07}, organization = {apresentação Plenária no 13th International Meeting of the Portuguese Carbohydrate Group, PL3.}, keywords = {}, pubstate = {published}, tppubtype = {conference} } |
LPT Carneiro, NS Ferreira, APM Tavares, MGF Sales Biosensor for cancinoembryonic antigen determination powered by passive methanol fuel cell (Conference) Graduate Student Symposium on Molecular Imprinting 2019 , Berlim, Alemanha, 28 a 30 de agosto., 2019. (BibTeX) @conference{Carneiro2019, title = {Biosensor for cancinoembryonic antigen determination powered by passive methanol fuel cell}, author = {LPT Carneiro, NS Ferreira, APM Tavares, MGF Sales}, year = {2019}, date = {2019-08-28}, publisher = {Graduate Student Symposium on Molecular Imprinting 2019 }, address = {Berlim, Alemanha, 28 a 30 de agosto.}, keywords = {}, pubstate = {published}, tppubtype = {conference} } |
MCCG Carneiro, A Sousa-Castillo, MA Correa-Duarte, MGF Sales Molecularly-imprinted polymer combined with SERS detection – Application to carcinoembryonic antigen (Conference) Graduate Student Symposium on Molecular Imprinting 2019, Berlim, Alemanha, 28 a 30 de agosto., 2019. (BibTeX) @conference{Carneiro2019b, title = {Molecularly-imprinted polymer combined with SERS detection – Application to carcinoembryonic antigen}, author = {MCCG Carneiro, A Sousa-Castillo, MA Correa-Duarte, MGF Sales }, year = {2019}, date = {2019-08-28}, publisher = {Graduate Student Symposium on Molecular Imprinting 2019}, address = { Berlim, Alemanha, 28 a 30 de agosto.}, keywords = {}, pubstate = {published}, tppubtype = {conference} } |
S Resende, MF Frasco, MGF Sales Opal photonic crystal-based molecularly imprinted sensor for detection of a venous thromboembolism biomarker (Conference) Graduate Student Symposium on Molecular Imprinting 2019 , Berlim, Alemanha, 28 a 30 de agosto., 2019. (BibTeX) @conference{Resende2019, title = {Opal photonic crystal-based molecularly imprinted sensor for detection of a venous thromboembolism biomarker}, author = {S Resende, MF Frasco, MGF Sales }, year = {2019}, date = {2019-08-28}, publisher = {Graduate Student Symposium on Molecular Imprinting 2019 }, address = {Berlim, Alemanha, 28 a 30 de agosto.}, keywords = {}, pubstate = {published}, tppubtype = {conference} } |
MGF Sales, MH Sá Electrical biosensors moving towards autonomy: application to cancer biomarkers (Conference) EMN Meeting on Biomaterials , Milan, Itália, 17 de agosto., 2019. (BibTeX) @conference{Sales2017a, title = {Electrical biosensors moving towards autonomy: application to cancer biomarkers}, author = {MGF Sales, MH Sá}, year = {2019}, date = {2019-08-17}, publisher = {EMN Meeting on Biomaterials }, address = {Milan, Itália, 17 de agosto.}, keywords = {}, pubstate = {published}, tppubtype = {conference} } |
R Gomes, FTC Moreira, R Fernandes An antibody-like material for the of detection CA 15-3 cancer biomarker (Conference) 7th Graduate Student Symposium on Molecular Imprinting , Porto, Portugal, 8 e 9 de junho., 2019. (BibTeX) @conference{Gomes2017, title = {An antibody-like material for the of detection CA 15-3 cancer biomarker}, author = {R Gomes, FTC Moreira, R Fernandes}, year = {2019}, date = {2019-07-17}, publisher = { 7th Graduate Student Symposium on Molecular Imprinting }, address = {Porto, Portugal, 8 e 9 de junho.}, keywords = {}, pubstate = {published}, tppubtype = {conference} } |
Y Castaño-Guerrero, FTC Moreira, MGF Sales SERS-based immunosensing layer for cancer biomarker detection in point-of-care (Conference) 8th Iberian Meeting on Colloids and Interfaces (RICI8), Aveiro, Portugal, 17 a 19 de julho., 2019. (BibTeX) @conference{Guerrero2019, title = {SERS-based immunosensing layer for cancer biomarker detection in point-of-care}, author = {Y Castaño-Guerrero, FTC Moreira, MGF Sales}, year = {2019}, date = {2019-07-17}, publisher = { 8th Iberian Meeting on Colloids and Interfaces (RICI8)}, address = { Aveiro, Portugal, 17 a 19 de julho.}, keywords = {}, pubstate = {published}, tppubtype = {conference} } |
AML Piloto, DSM Ribeiro, SSM Rodrigues, JLM Santos, MGF Sales Label-free quantum dot conjugates for human protein IL-2 based on molecularly imprinted polymer (Conference) 8th Iberian Meeting on Colloids and Interfaces (RICI8), Aveiro, Portugal, 17 a 19 de julho., 2019. (BibTeX) @conference{Piloto2019, title = {Label-free quantum dot conjugates for human protein IL-2 based on molecularly imprinted polymer}, author = {AML Piloto, DSM Ribeiro, SSM Rodrigues, JLM Santos, MGF Sales}, year = {2019}, date = {2019-07-17}, publisher = {8th Iberian Meeting on Colloids and Interfaces (RICI8)}, address = {Aveiro, Portugal, 17 a 19 de julho.}, keywords = {}, pubstate = {published}, tppubtype = {conference} } |
L Truta, S Fateixa, T Trindade, G Sales Glass-based biosensing device for monitoring CA15-3 cancer biomarker (Conference) 8th Iberian Meeting on Colloids and Interfaces (RICI8), Aveiro, Portugal, 17 a 19 de julho., 2019. (BibTeX) @conference{Truta2019, title = {Glass-based biosensing device for monitoring CA15-3 cancer biomarker}, author = {L Truta, S Fateixa, T Trindade, G Sales}, year = {2019}, date = {2019-07-17}, publisher = {8th Iberian Meeting on Colloids and Interfaces (RICI8)}, address = {Aveiro, Portugal, 17 a 19 de julho.}, keywords = {}, pubstate = {published}, tppubtype = {conference} } |
I J Costa, F Moreira, G Sales Disposable Electrochemical Biosensor for Protein Interaction Studies (Conference) 8th Iberian Meeting on Colloids and Interfaces (RICI8) , Aveiro, Portugal, 17 a 19 de julho., 2019. (BibTeX) @conference{Costa2019, title = {Disposable Electrochemical Biosensor for Protein Interaction Studies}, author = {I J Costa, F Moreira, G Sales}, year = {2019}, date = {2019-07-17}, publisher = {8th Iberian Meeting on Colloids and Interfaces (RICI8) }, address = {Aveiro, Portugal, 17 a 19 de julho.}, keywords = {}, pubstate = {published}, tppubtype = {conference} } |
VM Serrano, AR Cardoso, MGF Sales Molecularly-imprinted histamine electrochemical sensor (Conference) 8th Iberian Meeting on Colloids and Interfaces (RICI8) , Aveiro, Portugal, 17 a 19 de julho., 2019. (BibTeX) @conference{Serrano2019, title = {Molecularly-imprinted histamine electrochemical sensor}, author = {VM Serrano, AR Cardoso, MGF Sales }, year = {2019}, date = {2019-07-17}, publisher = {8th Iberian Meeting on Colloids and Interfaces (RICI8) }, address = {Aveiro, Portugal, 17 a 19 de julho.}, keywords = {}, pubstate = {published}, tppubtype = {conference} } |
S Soares, R Fernandes, MGF Sales, M Correa-Duarte Nanotheranostics with microRNA: Application in radiotherapy (Conference) 8th Iberian Meeting on Colloids and Interfaces (RICI8) , Aveiro, Portugal, 17 a 19 de julho, 2019. (BibTeX) @conference{Soares2019, title = {Nanotheranostics with microRNA: Application in radiotherapy}, author = {S Soares, R Fernandes, MGF Sales, M Correa-Duarte}, year = {2019}, date = {2019-07-17}, publisher = {8th Iberian Meeting on Colloids and Interfaces (RICI8) }, address = {Aveiro, Portugal, 17 a 19 de julho}, keywords = {}, pubstate = {published}, tppubtype = {conference} } |
R Vaz, AC Cunha, MGF Sales, MF Frasco Biopolymeric photonic sensing of cancer protein biomarkers (Conference) 8th Iberian Meeting on Colloids and Interfaces (RICI8) , Aveiro, Portugal, 17 a 19 de julho., 2019. (BibTeX) @conference{Vaz2019, title = {Biopolymeric photonic sensing of cancer protein biomarkers}, author = {R Vaz, AC Cunha, MGF Sales, MF Frasco }, year = {2019}, date = {2019-07-17}, publisher = {8th Iberian Meeting on Colloids and Interfaces (RICI8) }, address = {Aveiro, Portugal, 17 a 19 de julho.}, keywords = {}, pubstate = {published}, tppubtype = {conference} } |
G Martins, S Chiussi, G Sales Biomimetic electrochemical sensor integrated in flexible polymeric devices for cancer diagnosis (Conference) 8th Iberian Meeting on Colloids and Interfaces (RICI8) , Aveiro, Portugal, 17 a 19 de julho., 2019. (BibTeX) @conference{Martins2019, title = {Biomimetic electrochemical sensor integrated in flexible polymeric devices for cancer diagnosis}, author = {G Martins, S Chiussi, G Sales }, year = {2019}, date = {2019-07-17}, publisher = {8th Iberian Meeting on Colloids and Interfaces (RICI8) }, address = {Aveiro, Portugal, 17 a 19 de julho.}, keywords = {}, pubstate = {published}, tppubtype = {conference} } |
A Suleimenova, AC Marques, T Fernandes, MF Frasco, MGF Sales, E Fortunato Transparent Electrodes for Optical and Electrochemical Biosensor Applications (Conference) 8th Iberian Meeting on Colloids and Interfaces (RICI8) , Aveiro, Portugal, 17 a 19 de julho., 2019. (BibTeX) @conference{Suleimenova2019, title = {Transparent Electrodes for Optical and Electrochemical Biosensor Applications}, author = {A Suleimenova, AC Marques, T Fernandes, MF Frasco, MGF Sales, E Fortunato }, year = {2019}, date = {2019-07-17}, publisher = {8th Iberian Meeting on Colloids and Interfaces (RICI8) }, address = {Aveiro, Portugal, 17 a 19 de julho.}, keywords = {}, pubstate = {published}, tppubtype = {conference} } |
FTC Moreira, MGF Sales Novel materials combining sensing and photovoltaic technologies for cancer biomarker detection (Conference) AMN19, O146, Aveiro, Portugal, 17 a 19 de julho., 2019. (BibTeX) @conference{Moreira2019, title = { Novel materials combining sensing and photovoltaic technologies for cancer biomarker detection}, author = {FTC Moreira, MGF Sales }, year = {2019}, date = {2019-07-17}, publisher = {AMN19, O146}, address = {Aveiro, Portugal, 17 a 19 de julho.}, keywords = {}, pubstate = {published}, tppubtype = {conference} } |
FCT Moreira, MGF Sales Disposable Enzymatic Biofuel Cell for Diabetes diagnostic in Point-of-Care (Conference) AMN19, O147, Aveiro, Portugal, 17 e 19 de Julho, 2019. (BibTeX) @conference{Moreira2019a, title = { Disposable Enzymatic Biofuel Cell for Diabetes diagnostic in Point-of-Care}, author = {FCT Moreira, MGF Sales }, year = {2019}, date = {2019-07-17}, publisher = {AMN19, O147}, address = {Aveiro, Portugal, 17 e 19 de Julho}, keywords = {}, pubstate = {published}, tppubtype = {conference} } |
2018
Frasco MF, Pereira CF, Resende S, Sales MGF. Molecularly imprinted photonic sensor for detection of cancer biomarkers (Conference) Oral Presentation. 1st International Conference on Nanotechnologies and Bionanoscience , Heraklion, Crete, Grécia, 24 a 28 de setembro, 2018. (BibTeX) @conference{Frasco2018, title = {Molecularly imprinted photonic sensor for detection of cancer biomarkers}, author = {Frasco MF, Pereira CF, Resende S, Sales MGF. }, year = {2018}, date = {2018-09-24}, publisher = {Oral Presentation. 1st International Conference on Nanotechnologies and Bionanoscience }, address = {Heraklion, Crete, Grécia, 24 a 28 de setembro}, keywords = {}, pubstate = {published}, tppubtype = {conference} } |
CF Pereira, MF Frasco, MGF Sales Towards an unprecedented molecularly imprinted photonic biosensor for venous thromboembolism (Conference) Oral Presentation, 1st International Conference on Nanotechnologies and Bionanoscience , Heraklion, Crete, Grécia, 24 a 28 de setembro., 2018. (BibTeX) @conference{Pereira2018, title = {Towards an unprecedented molecularly imprinted photonic biosensor for venous thromboembolism}, author = {CF Pereira, MF Frasco, MGF Sales }, year = {2018}, date = {2018-09-24}, publisher = {Oral Presentation, 1st International Conference on Nanotechnologies and Bionanoscience }, address = {Heraklion, Crete, Grécia, 24 a 28 de setembro.}, keywords = {}, pubstate = {published}, tppubtype = {conference} } |
S Resende, MF Frasco, MGF Sales, Photonic crystal-based sensor for label-free detection of fibrinopeptide B. Photonic crystal-based sensor for label-free detection of fibrinopeptide (Conference) Oral Presentation, 1st International Conference on Nanotechnologies and Bionanoscience, Heraklion, Crete, Grécia, 24 a 28 de setembro, 2018. (BibTeX) @conference{resende2018, title = {Photonic crystal-based sensor for label-free detection of fibrinopeptide}, author = {S Resende, MF Frasco, MGF Sales, Photonic crystal-based sensor for label-free detection of fibrinopeptide B. }, year = {2018}, date = {2018-09-24}, publisher = {Oral Presentation, 1st International Conference on Nanotechnologies and Bionanoscience}, address = {Heraklion, Crete, Grécia, 24 a 28 de setembro}, keywords = {}, pubstate = {published}, tppubtype = {conference} } |
MF Frasco, R Pereira-Cameselle, S Chiussi, JL Alonso-Gómez, MGF Sales Molecularly imprinted chiroptical sensor for detection of glucose (Conference) 1st International Conference on Nanotechnologies and Bionanoscience , Heraklion, Crete, Grécia, 24 a 28 setembro, 2018. (BibTeX) @conference{Frasco2018b, title = {Molecularly imprinted chiroptical sensor for detection of glucose}, author = {MF Frasco, R Pereira-Cameselle, S Chiussi, JL Alonso-Gómez, MGF Sales}, year = {2018}, date = {2018-09-24}, publisher = {1st International Conference on Nanotechnologies and Bionanoscience }, address = {Heraklion, Crete, Grécia, 24 a 28 setembro}, keywords = {}, pubstate = {published}, tppubtype = {conference} } |
NS Ferreira, LR Brandão, MGF Sales Glucose fuel cell powered biosensor for acetylcholinesterase using molecular imprinting technology (Conference) Poster, 28th World Congress on Biosensors, Miami, USA, 12 a 15 junho, 2018. (BibTeX) @conference{Ferreira2018, title = {Glucose fuel cell powered biosensor for acetylcholinesterase using molecular imprinting technology}, author = {NS Ferreira, LR Brandão, MGF Sales}, year = {2018}, date = {2018-06-15}, publisher = {Poster, 28th World Congress on Biosensors}, address = {Miami, USA, 12 a 15 junho}, keywords = {}, pubstate = {published}, tppubtype = {conference} } |
MGF Sales, APM Tavares, LAAN Truta, FTC Moreira, BioSelf: self-powered, self-sustained, self-indicated biosensing. Application to cancer biomarker screening, BioSelf: self-powered, self-sustained and self-indicated biosensing. Application to cancer biomarker screening (Conference) O2A.4, 28th World Congress on Biosensors , Miami, USA, 12 a 15 de junho, 2018. (BibTeX) @conference{Sales2018c, title = {BioSelf: self-powered, self-sustained and self-indicated biosensing. Application to cancer biomarker screening}, author = {MGF Sales, APM Tavares, LAAN Truta, FTC Moreira, BioSelf: self-powered, self-sustained and self-indicated biosensing. Application to cancer biomarker screening, }, year = {2018}, date = {2018-06-12}, publisher = {O2A.4, 28th World Congress on Biosensors }, address = {Miami, USA, 12 a 15 de junho}, keywords = {}, pubstate = {published}, tppubtype = {conference} } |
FTC Moreira, MGF Sales, Autonomous Biosensing Device for a Cancer Biomarker detection in Point-of- Care, Autonomous Biosensing Device for a Cancer Biomarker detection in Point-of- Care (Conference) O2I.2 28th World Congress on Biosensors , Miami, USA, 12 a 15 de junho., 2018. (BibTeX) @conference{Moreira2018c, title = {Autonomous Biosensing Device for a Cancer Biomarker detection in Point-of- Care}, author = {FTC Moreira, MGF Sales, Autonomous Biosensing Device for a Cancer Biomarker detection in Point-of- Care, }, year = {2018}, date = {2018-06-12}, publisher = {O2I.2 28th World Congress on Biosensors }, address = {Miami, USA, 12 a 15 de junho.}, keywords = {}, pubstate = {published}, tppubtype = {conference} } |
LPT Carneiro, MGF Sales, LR Brandão Fuel cell transduced biosensor for myoglobin screening (Conference) Poster, 28th World Congress on Biosensors , Miami, USA, 12 a 15 de junho, 2018. (BibTeX) @conference{Carneiro2018, title = {Fuel cell transduced biosensor for myoglobin screening}, author = {LPT Carneiro, MGF Sales, LR Brandão}, year = {2018}, date = {2018-06-12}, publisher = {Poster, 28th World Congress on Biosensors }, address = {Miami, USA, 12 a 15 de junho}, keywords = {}, pubstate = {published}, tppubtype = {conference} } |
Raquel Campos, M H de Sá, Lucia Brandao, M Goreti F Sales Screening cancer biomarkers with plastic antibodies assembled on a fuel cell: Application to CEA (Conference) J Material Sci Eng 6th International Conference and Exhibition on Materials Science and Chemistry, Roma, Itália, 17 a 18 de maio. , 2018. @conference{Campos2018, title = {Screening cancer biomarkers with plastic antibodies assembled on a fuel cell: Application to CEA}, author = {Raquel Campos, M H de Sá, Lucia Brandao and M Goreti F Sales }, doi = { 10.4172/2169-0022-C5-105}, year = {2018}, date = {2018-05-12}, publisher = {6th International Conference and Exhibition on Materials Science and Chemistry}, address = { Roma, Itália, 17 a 18 de maio. }, organization = {J Material Sci Eng }, keywords = {}, pubstate = {published}, tppubtype = {conference} } |
MGF Sales Cancer Biomarker Detection - Liquid Biopsy: bringing precision medicine closer to oncology (Conference) 24th Porto Cancer Meeting, Session 2, Technology for liquid biopsies, i3S , Porto, 11 de maio, 2018. (BibTeX) @conference{Sales2017, title = {Cancer Biomarker Detection - Liquid Biopsy: bringing precision medicine closer to oncology}, author = {MGF Sales}, year = {2018}, date = {2018-05-11}, publisher = {24th Porto Cancer Meeting, Session 2, Technology for liquid biopsies, i3S }, address = {Porto, 11 de maio}, keywords = {}, pubstate = {published}, tppubtype = {conference} } |
MGF Sales Biossensores para a Saúde (Conference) VI Jornadas Bioengenharia, Universidade da Beira Interior, Covilha, Portugal, 2 de maio, 2018. (BibTeX) @conference{Sales2018b, title = {Biossensores para a Saúde}, author = {MGF Sales }, year = {2018}, date = {2018-05-02}, publisher = {VI Jornadas Bioengenharia, Universidade da Beira Interior}, address = {Covilha, Portugal, 2 de maio}, keywords = {}, pubstate = {published}, tppubtype = {conference} } |
MGF Sales Nanomaterials mimicking antibodies applied to biosensing (Conference) Nanoelectronics at the 6th World congress and Expo on Nanotechnology and Materials Science , Valencia, Espanha, 16 de abril, 2018. (BibTeX) @conference{Sales2018, title = {Nanomaterials mimicking antibodies applied to biosensing}, author = {MGF Sales}, year = {2018}, date = {2018-04-16}, publisher = { Nanoelectronics at the 6th World congress and Expo on Nanotechnology and Materials Science }, address = {Valencia, Espanha, 16 de abril}, keywords = {}, pubstate = {published}, tppubtype = {conference} } |
FTC Moreira, MGF Sales Development of Paper-based Cooler Test-Strip for Alzheimer biomarker detection in point-of-care (Conference) Nanoelectronics at the 6th World congress and Expo on Nanotechnology and Materials Science , Valencia, Espanha, 16 a18 de abril., 2018. (BibTeX) @conference{Moreira2018b, title = {Development of Paper-based Cooler Test-Strip for Alzheimer biomarker detection in point-of-care }, author = { FTC Moreira, MGF Sales}, year = {2018}, date = {2018-04-16}, publisher = { Nanoelectronics at the 6th World congress and Expo on Nanotechnology and Materials Science }, address = {Valencia, Espanha, 16 a18 de abril.}, keywords = {}, pubstate = {published}, tppubtype = {conference} } |
G Martins, AC Marques, E Fortunato, MGF Sales Electrochemical paper-based sensor integrated with molecular imprinting towards point-of-care diagnosis (Conference) Nanoelectronics at the 6th World congress and Expo on Nanotechnology and Materials Science , Valencia, Espanha, 16 a 18 de abril., 2018. (BibTeX) @conference{Martins2018, title = {Electrochemical paper-based sensor integrated with molecular imprinting towards point-of-care diagnosis}, author = {G Martins, AC Marques, E Fortunato, MGF Sales }, year = {2018}, date = {2018-04-16}, publisher = {Nanoelectronics at the 6th World congress and Expo on Nanotechnology and Materials Science }, address = {Valencia, Espanha, 16 a 18 de abril.}, keywords = {}, pubstate = {published}, tppubtype = {conference} } |
MGF Sales Biossensores na Saúde (Conference) Instituto Superior de Engenharia do Porto ENEEB, Encontro Nacional de Estudantes de Engenharia Biomédica, Porto, 2 de março., 2018. (BibTeX) @conference{Sales2018a, title = {Biossensores na Saúde}, author = {MGF Sales }, year = {2018}, date = {2018-03-02}, publisher = {ENEEB, Encontro Nacional de Estudantes de Engenharia Biomédica}, address = {Porto, 2 de março.}, organization = { Instituto Superior de Engenharia do Porto}, keywords = {}, pubstate = {published}, tppubtype = {conference} } |
2017
MF Frasco, MGF Sales Electrical biosensors moving towards autonomy: application to cancer biomarkers (Conference) A50, EMN Meeting on Biomaterials , Milão, Itália, 14 a 18 de agosto., 2017. (BibTeX) @conference{Frasco2017, title = {Electrical biosensors moving towards autonomy: application to cancer biomarkers }, author = {MF Frasco, MGF Sales}, year = {2017}, date = {2017-08-14}, publisher = {A50, EMN Meeting on Biomaterials }, address = {Milão, Itália, 14 a 18 de agosto.}, keywords = {}, pubstate = {published}, tppubtype = {conference} } |
MF Frasco Biomimetic materials for sensing cancer biomarkers (Conference) B15, EMN Meeting on Biomaterials 2017, Milan, Italy, 2017. (BibTeX) @conference{Frasco2017, title = {Biomimetic materials for sensing cancer biomarkers}, author = {MF Frasco}, year = {2017}, date = {2017-08-14}, address = {Milan, Italy}, organization = {B15, EMN Meeting on Biomaterials 2017,}, keywords = {}, pubstate = {published}, tppubtype = {conference} } |
MGF Sales Electrical biosensors moving towards autonomy: application to cancer biomarkers (Conference) A50, EMN Meeting on Biomaterials 2017, Milan, Italy, 2017. (BibTeX) @conference{Sales2017b, title = {Electrical biosensors moving towards autonomy: application to cancer biomarkers}, author = {MGF Sales}, year = {2017}, date = {2017-08-14}, address = {Milan, Italy}, organization = {A50, EMN Meeting on Biomaterials 2017,}, keywords = {}, pubstate = {published}, tppubtype = {conference} } |
APM Tavares Biosensors and photovoltaics merged: towards a self-sustained device (Conference) B17, EMN Meeting on Biomaterials 2017, Milan, Italy, 2017. (BibTeX) @conference{Tavares2017b, title = {Biosensors and photovoltaics merged: towards a self-sustained device}, author = {APM Tavares}, year = {2017}, date = {2017-08-14}, address = {Milan, Italy}, organization = {B17, EMN Meeting on Biomaterials 2017,}, keywords = {}, pubstate = {published}, tppubtype = {conference} } |
LAANA Truta Modification of TiO2 with gold nanoparticles: application to Dye Sensitized Solar Cells (Conference) A24, EMN Meeting on Biomaterials 2017, Milan, Italy, 2017. (BibTeX) @conference{Truta2017b, title = {Modification of TiO2 with gold nanoparticles: application to Dye Sensitized Solar Cells}, author = {LAANA Truta}, year = {2017}, date = {2017-08-14}, address = {Milan, Italy}, organization = {A24, EMN Meeting on Biomaterials 2017,}, keywords = {}, pubstate = {published}, tppubtype = {conference} } |
M Oliveira Plastic antibodies on a paperbased sensor applied to cancer detection (Conference) A53, EMN Meeting on Biomaterials 2017, Milan, Italy, 2017. (BibTeX) @conference{Oliveira2017b, title = {Plastic antibodies on a paperbased sensor applied to cancer detection}, author = {M Oliveira}, year = {2017}, date = {2017-08-14}, address = {Milan, Italy}, organization = {A53, EMN Meeting on Biomaterials 2017,}, keywords = {}, pubstate = {published}, tppubtype = {conference} } |
M Oliveria, M Frasco, MGF Sales, Plastic antibodies on a paper based sensor applied to cancer detection Plastic antibodies on a paper based sensor applied to cancer detection (Conference) A53, EMN Meeting on Biomaterials ., Milão, Itália, 14 a 18 de Agosto, 2017. (BibTeX) @conference{Oliveira2017, title = {Plastic antibodies on a paper based sensor applied to cancer detection}, author = {M Oliveria, M Frasco, MGF Sales, Plastic antibodies on a paper based sensor applied to cancer detection}, year = {2017}, date = {2017-08-12}, publisher = { A53, EMN Meeting on Biomaterials .}, address = {Milão, Itália, 14 a 18 de Agosto}, keywords = {}, pubstate = {published}, tppubtype = {conference} } |
LAANA Truta, MGF Sales Modification of TiO2 with gold nanoparticles: application to Dye Sensitized Solar Cells (Conference) B17, EMN Meeting on Biomaterials 2017 , Milão, Itália, 14 a 18 de agosto., 2017. (BibTeX) @conference{truta2017, title = {Modification of TiO2 with gold nanoparticles: application to Dye Sensitized Solar Cells}, author = {LAANA Truta, MGF Sales}, year = {2017}, date = {2017-08-12}, publisher = {B17, EMN Meeting on Biomaterials 2017 }, address = {Milão, Itália, 14 a 18 de agosto.}, keywords = {}, pubstate = {published}, tppubtype = {conference} } |
APM Tavares, MGF Sales, Biosensors, photovoltaics merged: towards a self-sustained device, Biosensors and photovoltaics merged: towards a self-sustained device (Conference) B17, EMN Meeting on Biomaterials, Milan, Itália, 14 a 18 de Agosto, 2017. (BibTeX) @conference{Tavares2017, title = { Biosensors and photovoltaics merged: towards a self-sustained device}, author = {APM Tavares, MGF Sales, Biosensors and photovoltaics merged: towards a self-sustained device, }, year = {2017}, date = {2017-08-12}, publisher = {B17, EMN Meeting on Biomaterials}, address = { Milan, Itália, 14 a 18 de Agosto}, keywords = {}, pubstate = {published}, tppubtype = {conference} } |
L Brandão Cancer screening made possible with a direct methanol fuel cell (Conference) Invited talk (A22), EMN Meeting on Fuel Cells 2017, Prague, Czech Republic, 2017. @conference{Brandão2017, title = {Cancer screening made possible with a direct methanol fuel cell}, author = {L Brandão}, year = {2017}, date = {2017-06-14}, address = {Prague, Czech Republic}, organization = {Invited talk (A22), EMN Meeting on Fuel Cells 2017,}, abstract = {Incredibly low detection limits for disease markers can be achieved with electrochemical biosensors. However their generalized use in routine healthcare for screening cancer markers (present at very low levels in human body) is still limited by the need of both specialized power-grid expensive equipment and technical personnel for the analysis and interpretation of the reading signal. In this talk, an innovative approach is proposed to solve the limitation of the electrical and technical personnel dependencies of electrochemical biosensors by inserting the biorecognition layer into a highly efficient fuel cell (a passive direct methanol fuel cell - DMFC) working as the transducer of the biosensor. This empowers besides electrical autonomy a user-friendly (non-implantable) biosensor device. This new approach to biosensing devices aims an ease and simple application in routine health care for cancer screening in a population not even at risk of developing such disease. The use of the anode triple-phase boundary layer of a passive direct methanol fuel cell as the biosensor transducer is proposed. For that, fuel cell anode catalysts were modified with a molecularly imprinted polymer (plastic antibody) acting as the biorecognition element of cancer related protein markers and subjected to a fuel cell environment. The anchoring of a stable polymeric layer (to be used as the bioreceptor) on the anode catalyst surface used a simple one-step grafting from approach through radical polymerization. Such modification indeed show to increase fuel cell performance due to the proton conductivity and macroporosity characteristics of the polymer affecting the triple-phase boundary. Finally, the response and selectivity of the bioreceptor inside the fuel cell showed a clear and selective response from the biosensor where the concentration detection limits observed decreased 2 orders of magnitude in comparison to a 3 electrodes configuration system were. Moreover, the very low detection concentration limits achieved allow dilution of the biological sample fluids ca. 100 X thus bringing to minimal the effect of biological fluids on fuel cell response. Performance changes resulting from simple exposure to the analyte sample were successfully minimized. A highly interdisciplinary team is merging the knowledge from several fields (www.symbiotic-project.eu): ISEP (Portugal) is developing molecularly imprinted polymers, Imperial College of London (UK) and VTT (Finland) are working on low cost designs for passive DFMC with high energetic efficiency, UNINOVA (Portugal) is developing a low cost signalling interface biosensor using electrochromic technologies, and Aarhus University (Denmark) is studying the biochemical interactions between proteins and the biosensor area. The project leading to this work (Symbiotic) has received funding from the European Union’s Horizon 2020 research and innovation program under grant agreement no. 665046. }, keywords = {}, pubstate = {published}, tppubtype = {conference} } Incredibly low detection limits for disease markers can be achieved with electrochemical biosensors. However their generalized use in routine healthcare for screening cancer markers (present at very low levels in human body) is still limited by the need of both specialized power-grid expensive equipment and technical personnel for the analysis and interpretation of the reading signal. In this talk, an innovative approach is proposed to solve the limitation of the electrical and technical personnel dependencies of electrochemical biosensors by inserting the biorecognition layer into a highly efficient fuel cell (a passive direct methanol fuel cell - DMFC) working as the transducer of the biosensor. This empowers besides electrical autonomy a user-friendly (non-implantable) biosensor device. This new approach to biosensing devices aims an ease and simple application in routine health care for cancer screening in a population not even at risk of developing such disease. The use of the anode triple-phase boundary layer of a passive direct methanol fuel cell as the biosensor transducer is proposed. For that, fuel cell anode catalysts were modified with a molecularly imprinted polymer (plastic antibody) acting as the biorecognition element of cancer related protein markers and subjected to a fuel cell environment. The anchoring of a stable polymeric layer (to be used as the bioreceptor) on the anode catalyst surface used a simple one-step grafting from approach through radical polymerization. Such modification indeed show to increase fuel cell performance due to the proton conductivity and macroporosity characteristics of the polymer affecting the triple-phase boundary. Finally, the response and selectivity of the bioreceptor inside the fuel cell showed a clear and selective response from the biosensor where the concentration detection limits observed decreased 2 orders of magnitude in comparison to a 3 electrodes configuration system were. Moreover, the very low detection concentration limits achieved allow dilution of the biological sample fluids ca. 100 X thus bringing to minimal the effect of biological fluids on fuel cell response. Performance changes resulting from simple exposure to the analyte sample were successfully minimized. A highly interdisciplinary team is merging the knowledge from several fields (www.symbiotic-project.eu): ISEP (Portugal) is developing molecularly imprinted polymers, Imperial College of London (UK) and VTT (Finland) are working on low cost designs for passive DFMC with high energetic efficiency, UNINOVA (Portugal) is developing a low cost signalling interface biosensor using electrochromic technologies, and Aarhus University (Denmark) is studying the biochemical interactions between proteins and the biosensor area. The project leading to this work (Symbiotic) has received funding from the European Union’s Horizon 2020 research and innovation program under grant agreement no. 665046. |
R Gomes, FTC Moreira, R Fernandes, MGF Sales An antibody-like material for the of detection CA 15-3 cancer biomarker (Conference) Oral presentation, 7th Graduate Student Symposium on Molecular Imprinting, Porto, Portugal, 2017. @conference{Gomes2017, title = {An antibody-like material for the of detection CA 15-3 cancer biomarker}, author = {R Gomes and FTC Moreira and R Fernandes and MGF Sales}, year = {2017}, date = {2017-06-09}, address = {Porto, Portugal}, organization = {Oral presentation, 7th Graduate Student Symposium on Molecular Imprinting,}, abstract = {Current state-of-art in the field of cancer diseases indicated an urgent need for early cancer detection, which would fact match the technological advances recently achieved in the course of the treatment of the disease. For this purpose, a non-expensive device that could be used in point-of-care testing is proposed herein, making use of an antibody-like material tailored to recognize CA 15-3. The biomimetic material is assembled by electropolymerizing OPhenylenediamine (oPDA) in-situ, on a conductive Fluorine doped Tin Oxide (FTO) glass containing CA 15-3 Breast Tumour Antigen. The antibody like material was assembled on a conductive glass support modified with cysteamine. The presence of cysteamine enabled the formation of an amine layer, to which proteins hold high affinity without leading to denaturation. After, CA 15-3 target protein was adsorbed on top and incubated within charged monomers; charged phenolic derivatives were used for this purpose, establishing complementary interactions with the charged sites at the external surface of the protein. Electropolymerization was conducted after by adding an oPDA solution of the surface. The imprinted biomarker was removed enzymatically, leaving to the formation of vacant sites to which other CA 15-3 biomolecules could rebind later. All stages of assembly of the antibody like film were followed by electrochemical measurements, conducted in a potentiostat/galvanostat, from Metrohm Autolab, PGSTAT302N, equipped with a FRA module and controlled by Nova software. The ability of the biomaterial to rebind the protein biomarker was measured by electrochemical techniques, most particularly electrochemical impedance spectroscopy (EIS) and square wave voltammetry (SWV). Preliminary studies revealed a satisfactory coupling between the protein and the antibody-like film. The results obtained pointed out a linear response ranging from 0.05 to 5.0 U/mL, with detection limits of ~0.005 U/mL. Further tests are progressing to evaluate sensitivity and selectivity, in order to achieve a reusable device, offering both low cost and low response time. The authors acknowledge the financial support of the European Research Council, through Starting Grant 3P’s/ERC (GA 311086).}, keywords = {}, pubstate = {published}, tppubtype = {conference} } Current state-of-art in the field of cancer diseases indicated an urgent need for early cancer detection, which would fact match the technological advances recently achieved in the course of the treatment of the disease. For this purpose, a non-expensive device that could be used in point-of-care testing is proposed herein, making use of an antibody-like material tailored to recognize CA 15-3. The biomimetic material is assembled by electropolymerizing OPhenylenediamine (oPDA) in-situ, on a conductive Fluorine doped Tin Oxide (FTO) glass containing CA 15-3 Breast Tumour Antigen. The antibody like material was assembled on a conductive glass support modified with cysteamine. The presence of cysteamine enabled the formation of an amine layer, to which proteins hold high affinity without leading to denaturation. After, CA 15-3 target protein was adsorbed on top and incubated within charged monomers; charged phenolic derivatives were used for this purpose, establishing complementary interactions with the charged sites at the external surface of the protein. Electropolymerization was conducted after by adding an oPDA solution of the surface. The imprinted biomarker was removed enzymatically, leaving to the formation of vacant sites to which other CA 15-3 biomolecules could rebind later. All stages of assembly of the antibody like film were followed by electrochemical measurements, conducted in a potentiostat/galvanostat, from Metrohm Autolab, PGSTAT302N, equipped with a FRA module and controlled by Nova software. The ability of the biomaterial to rebind the protein biomarker was measured by electrochemical techniques, most particularly electrochemical impedance spectroscopy (EIS) and square wave voltammetry (SWV). Preliminary studies revealed a satisfactory coupling between the protein and the antibody-like film. The results obtained pointed out a linear response ranging from 0.05 to 5.0 U/mL, with detection limits of ~0.005 U/mL. Further tests are progressing to evaluate sensitivity and selectivity, in order to achieve a reusable device, offering both low cost and low response time. The authors acknowledge the financial support of the European Research Council, through Starting Grant 3P’s/ERC (GA 311086). |
C Hora, RM Castro, MGF Sales Host-tailored sensors for dopamine potentiometric measurements applied to Parkinson’s disease (Conference) Oral presentation, 7th Graduate Student Symposium on Molecular Imprinting, Porto, Portugal, 2017. @conference{Hora2017, title = {Host-tailored sensors for dopamine potentiometric measurements applied to Parkinson’s disease}, author = {C Hora and RM Castro and MGF Sales}, year = {2017}, date = {2017-06-09}, address = {Porto, Portugal}, organization = {Oral presentation, 7th Graduate Student Symposium on Molecular Imprinting,}, abstract = {Parkinson’s disease (PD) is a progressive neurodegenerative condition caused by an early death of dopaminergic neurons in the substantia nigra leading to a considerable drop of dopamine concentration. Dopamine (DA) is an endogenous catecholamine, which serves as a neurotransmitter in the central and peripheral nervous system. Neuroimaging techniques are employed to support the clinical diagnosis of PD, but they have high costs and restricted portability, reaffirming the need to develop new alternatives. Thus, this work presents for this purpose a potentiometric biomimetic sensor for DA host-guest interactions. The sensing element was a on molecularly-imprinted polymer (MIP) material, obtained by bulk polymerization of Methacrylic acid, cross-linked with Ethylene glycol dimethacrylate and initiated by Benzoyl peroxide. Non-imprinted polymer (NIP) material was also produced as control, by excluding the template from the procedure. The selective membranes were prepared by dispersing the sensing element in a PVC matrix, plasticized with O-Nitrophenyl octyl ether. The effect of the presence of an anionic lipophilic additive, potassium tetrakis(4-chlorophenyl) borate, was also tested by preparing membranes with and without it. Control membranes were produced by replacing MIP by NIP material or having only an anionic additive. All membranes were casted on a solid conductive support made of graphite, placed at the smaller end of the plastic body of an insulin syringe. The potentiometric performance of the electrodes was evaluated against increasing concentrations of DA. The effect of pH upon the potentiometric response was evaluated for different buffer solutions and the best performance for this sensor was obtained with HEPES (4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid) buffer, pH 5.2. In general, the best features were displayed by membranes with MIP and anionic additive, with an average slope of 36 mV/decade and a linear response from 2.5 x10-6 to 5.1x10-4 mol/L. The selectivity study is being performed made by separate solution method. In general, the electrodes displayed good selectivity features. Overall, the combination of the MIP sensory material and a proper anionic additive within a selective membrane and a suitable electrode design could lead to a promising tool for point-ofcare applications, with the possibility of a successful application in real urine samples.}, keywords = {}, pubstate = {published}, tppubtype = {conference} } Parkinson’s disease (PD) is a progressive neurodegenerative condition caused by an early death of dopaminergic neurons in the substantia nigra leading to a considerable drop of dopamine concentration. Dopamine (DA) is an endogenous catecholamine, which serves as a neurotransmitter in the central and peripheral nervous system. Neuroimaging techniques are employed to support the clinical diagnosis of PD, but they have high costs and restricted portability, reaffirming the need to develop new alternatives. Thus, this work presents for this purpose a potentiometric biomimetic sensor for DA host-guest interactions. The sensing element was a on molecularly-imprinted polymer (MIP) material, obtained by bulk polymerization of Methacrylic acid, cross-linked with Ethylene glycol dimethacrylate and initiated by Benzoyl peroxide. Non-imprinted polymer (NIP) material was also produced as control, by excluding the template from the procedure. The selective membranes were prepared by dispersing the sensing element in a PVC matrix, plasticized with O-Nitrophenyl octyl ether. The effect of the presence of an anionic lipophilic additive, potassium tetrakis(4-chlorophenyl) borate, was also tested by preparing membranes with and without it. Control membranes were produced by replacing MIP by NIP material or having only an anionic additive. All membranes were casted on a solid conductive support made of graphite, placed at the smaller end of the plastic body of an insulin syringe. The potentiometric performance of the electrodes was evaluated against increasing concentrations of DA. The effect of pH upon the potentiometric response was evaluated for different buffer solutions and the best performance for this sensor was obtained with HEPES (4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid) buffer, pH 5.2. In general, the best features were displayed by membranes with MIP and anionic additive, with an average slope of 36 mV/decade and a linear response from 2.5 x10-6 to 5.1x10-4 mol/L. The selectivity study is being performed made by separate solution method. In general, the electrodes displayed good selectivity features. Overall, the combination of the MIP sensory material and a proper anionic additive within a selective membrane and a suitable electrode design could lead to a promising tool for point-ofcare applications, with the possibility of a successful application in real urine samples. |
GV Martins, AC Marques, E Fortunato, MGF Sales An imprinted paper-based biosensor designed towards point-of-care diagnosis (Conference) Oral presentation, 7th Graduate Student Symposium on Molecular Imprinting, Porto, Portugal, 2017. @conference{Martins2017, title = {An imprinted paper-based biosensor designed towards point-of-care diagnosis}, author = {GV Martins and AC Marques and E Fortunato and MGF Sales}, year = {2017}, date = {2017-06-09}, address = {Porto, Portugal}, organization = {Oral presentation, 7th Graduate Student Symposium on Molecular Imprinting,}, abstract = {Reactive nitrogen species, namely, nitric oxide, play an important role in many diseases [1]. Overproduction of free radicals generate a cytotoxic specie called peroxynitrite, responsible for attacking protein residues. As a result, 3-nitrotyrosine is obtained as a stable end-product and proposed as a biomarker for diagnosis of Oxidative Stress. In this context, early detection and treatment reduces the disease's severity, enabling more efficient therapeutic strategies. Currently, nanotechnology has given a great input in the design of electrodebased sensors. Following this trend, the development of novelty support materials enables special features in terms of flexibility, affordability and sustainability. Among the various types of substrates, such as, PET, ceramic and PVC, paper has been acknowledged as a suitable platform for sensing devices. Here, a paper-based sensor pre-modified with molecularly imprinted materials has been designed for the direct assessment of 3-nitrotyrosine biomarker. Initially, cellulose paper was wax-printed and thermal diffused to create the hydrophobic confinement. Afterwards, the three-electrode system was manually printed by using silver ink as the pseudo-reference electrode and carbon-based ink for both working and counter electrodes. Then, a thin polymeric layer was assembled in-situ on the paper-modified electrode through electropolymerization of phenol monomer, combined with the target molecule 3- nitrotyrosine. The electropolymerization of phenol was performed by Cyclic Voltammetry over the potential range +0.2 to +0.8 V in KCl (0.1 M) aqueous solution. Some experimental conditions, like, the initial concentration of the monomer and the ratio templatemonomer, were carefully optimized and the electrochemical performance of the designed MIP sensor was investigated by Cyclic Voltammetry, Square Wave Voltammetry and Electrochemical Impedance Spectroscopy. Due to the redox behaviour of 3-nitrotyrosine, mainly on carbon-based electrodes, the detection and quantification of this biomarker was followed directly by means of voltammetric measurements. Herein, the optimization of some experimental parameters, such as, the thickness of the polymeric film was performed and enabled low detection limits for 3-nitrotyrosine direct determination. Moreover, preliminary results showed that a pre-accumulation step before each electrochemical reading allowed the detection of this biomarker down to microMolar level. Overall, we have developed the first paper-based electrochemical biosensor towards 3-nitrotyrosine detection. Gabriela V. Martins acknowledges FCT the PhD Grant ref. SFRH/BD/94159/2013}, keywords = {}, pubstate = {published}, tppubtype = {conference} } Reactive nitrogen species, namely, nitric oxide, play an important role in many diseases [1]. Overproduction of free radicals generate a cytotoxic specie called peroxynitrite, responsible for attacking protein residues. As a result, 3-nitrotyrosine is obtained as a stable end-product and proposed as a biomarker for diagnosis of Oxidative Stress. In this context, early detection and treatment reduces the disease's severity, enabling more efficient therapeutic strategies. Currently, nanotechnology has given a great input in the design of electrodebased sensors. Following this trend, the development of novelty support materials enables special features in terms of flexibility, affordability and sustainability. Among the various types of substrates, such as, PET, ceramic and PVC, paper has been acknowledged as a suitable platform for sensing devices. Here, a paper-based sensor pre-modified with molecularly imprinted materials has been designed for the direct assessment of 3-nitrotyrosine biomarker. Initially, cellulose paper was wax-printed and thermal diffused to create the hydrophobic confinement. Afterwards, the three-electrode system was manually printed by using silver ink as the pseudo-reference electrode and carbon-based ink for both working and counter electrodes. Then, a thin polymeric layer was assembled in-situ on the paper-modified electrode through electropolymerization of phenol monomer, combined with the target molecule 3- nitrotyrosine. The electropolymerization of phenol was performed by Cyclic Voltammetry over the potential range +0.2 to +0.8 V in KCl (0.1 M) aqueous solution. Some experimental conditions, like, the initial concentration of the monomer and the ratio templatemonomer, were carefully optimized and the electrochemical performance of the designed MIP sensor was investigated by Cyclic Voltammetry, Square Wave Voltammetry and Electrochemical Impedance Spectroscopy. Due to the redox behaviour of 3-nitrotyrosine, mainly on carbon-based electrodes, the detection and quantification of this biomarker was followed directly by means of voltammetric measurements. Herein, the optimization of some experimental parameters, such as, the thickness of the polymeric film was performed and enabled low detection limits for 3-nitrotyrosine direct determination. Moreover, preliminary results showed that a pre-accumulation step before each electrochemical reading allowed the detection of this biomarker down to microMolar level. Overall, we have developed the first paper-based electrochemical biosensor towards 3-nitrotyrosine detection. Gabriela V. Martins acknowledges FCT the PhD Grant ref. SFRH/BD/94159/2013 |
M Oliveira, NS Ferreira, MGF Sales Plastic Antibody for the electrochemical detection of a protein biomarker: application to BSA (Conference) Oral presentation, 7th Graduate Student Symposium on Molecular Imprinting, Porto, Portugal, 2017. @conference{Oliveira2017, title = {Plastic Antibody for the electrochemical detection of a protein biomarker: application to BSA}, author = {M Oliveira and NS Ferreira and MGF Sales}, year = {2017}, date = {2017-06-09}, address = {Porto, Portugal}, organization = {Oral presentation, 7th Graduate Student Symposium on Molecular Imprinting,}, abstract = {This work aims to describe the approach used to build a low-cost device sensor for the detection of protein biomarkers in point-of-care by using Molecularly-imprinted polymers (MIPs) technology. MIPs, also known as plastic antibodies, specifically recognize target molecules. In this work, the imprinted polymer was synthetized by bulk electropolymerization on a carbon screen-printed electrode (previously cleaned with sulfuric acid, by using cyclic voltammetry (CV), from 0.2 to 0.8 V). The sensing material was assembled by electropolymerization of the monomer (3-aminophenol, 1.0×10-4 mol/L) and the protein template (BSA1.0×10-6 mol/L, currently being used as model template and to be replaced later by a cancer biomarker), all prepared in phosphate buffer, pH 7.6. The protein was later removed from the polymeric matrix by proteolytic action of proteinase K 500µg/mL. A control device (NIP, non-imprinted material) was also prepared in the same conditions as the MIP-based device, but without the template molecule. The analytical response of the biosensor was followed by Electrochemical Impedance Spectroscopy (EIS) as well as CV. As future steps, the analytical behavior will be evaluated in buffer and in synthetic serum, with regard to linear range, limit of detection, repeatability, and reproducibility. In a later stage, a same principle will be translated into the detection of a cancer biomarker.}, keywords = {}, pubstate = {published}, tppubtype = {conference} } This work aims to describe the approach used to build a low-cost device sensor for the detection of protein biomarkers in point-of-care by using Molecularly-imprinted polymers (MIPs) technology. MIPs, also known as plastic antibodies, specifically recognize target molecules. In this work, the imprinted polymer was synthetized by bulk electropolymerization on a carbon screen-printed electrode (previously cleaned with sulfuric acid, by using cyclic voltammetry (CV), from 0.2 to 0.8 V). The sensing material was assembled by electropolymerization of the monomer (3-aminophenol, 1.0×10-4 mol/L) and the protein template (BSA1.0×10-6 mol/L, currently being used as model template and to be replaced later by a cancer biomarker), all prepared in phosphate buffer, pH 7.6. The protein was later removed from the polymeric matrix by proteolytic action of proteinase K 500µg/mL. A control device (NIP, non-imprinted material) was also prepared in the same conditions as the MIP-based device, but without the template molecule. The analytical response of the biosensor was followed by Electrochemical Impedance Spectroscopy (EIS) as well as CV. As future steps, the analytical behavior will be evaluated in buffer and in synthetic serum, with regard to linear range, limit of detection, repeatability, and reproducibility. In a later stage, a same principle will be translated into the detection of a cancer biomarker. |
APM Tavares, C Hora, MGF Sales A novel Antibody-like material assembled on novel device for detection CEA cancer biomarker (Conference) Oral presentation, 7th Graduate Student Symposium on Molecular Imprinting, Porto, Portugal, 2017. @conference{Tavares2017, title = {A novel Antibody-like material assembled on novel device for detection CEA cancer biomarker}, author = {APM Tavares and C Hora and MGF Sales}, year = {2017}, date = {2017-06-09}, address = {Porto, Portugal}, organization = {Oral presentation, 7th Graduate Student Symposium on Molecular Imprinting,}, abstract = {Carcino-Embriyoic Antigen (CEA) is a glycoprotein and it is one of the most studied tumour biomarkers. The change of its levels in biological fluids has been associated with the presence of colorectal cancer. Thus, sensitive CEA determination (in low levels) becomes therefore important to long-term survival of cancer patients, creating the need to develop an analytical method capable of quantifying CEA quantification in point of care (POC). This work proposes for this purpose a biomimetic polymer for CEA, acting as an artificial antibody, combined with a photovoltaic cell to confer electrical autonomy to the overall device. The biomimetic polymer made use of molecularly-imprinted polymer (MIP) technique, by electropolymerizing Eriochrome Black T (EBT) in the presence of CEA. This was done by cyclic voltammetry (CV), from 0.00V to +1.00V (vs. Ag/AgCl, 3.00M) and 50.00 mV/s as scan-rate. A non-imprinting polymer (NIP) acting as control was also prepared by polymerizing without protein. The obtained sensors were characterized by Electrochemical Impedance Spectroscopy (EIS), in phosphate buffer/potassium nitrate. Raman spectroscopy confirmed all stages of the surface modification. MIP materials displayed linear responses over a wide range of concentrations (from 0.10pg/mL to 1.0ng/mL), good reproducibility and accuracy. The behavior of this material is also being tested in spiked serum samples, and it is expected to exhibited good selectivity for CEA. The biomimetic layer is currently being merged with a photovoltaic cell. The resulting analytical features are re-evaluated by measuring the efficiency of the cell under white LED illumination. Overall, the proposed sensor is a successful approach to the autonomous determination of CEA in POC. The authors acknowledge the financial support of the European Research Council, through Starting Grant 3P’s/ERC (GA 311086).}, keywords = {}, pubstate = {published}, tppubtype = {conference} } Carcino-Embriyoic Antigen (CEA) is a glycoprotein and it is one of the most studied tumour biomarkers. The change of its levels in biological fluids has been associated with the presence of colorectal cancer. Thus, sensitive CEA determination (in low levels) becomes therefore important to long-term survival of cancer patients, creating the need to develop an analytical method capable of quantifying CEA quantification in point of care (POC). This work proposes for this purpose a biomimetic polymer for CEA, acting as an artificial antibody, combined with a photovoltaic cell to confer electrical autonomy to the overall device. The biomimetic polymer made use of molecularly-imprinted polymer (MIP) technique, by electropolymerizing Eriochrome Black T (EBT) in the presence of CEA. This was done by cyclic voltammetry (CV), from 0.00V to +1.00V (vs. Ag/AgCl, 3.00M) and 50.00 mV/s as scan-rate. A non-imprinting polymer (NIP) acting as control was also prepared by polymerizing without protein. The obtained sensors were characterized by Electrochemical Impedance Spectroscopy (EIS), in phosphate buffer/potassium nitrate. Raman spectroscopy confirmed all stages of the surface modification. MIP materials displayed linear responses over a wide range of concentrations (from 0.10pg/mL to 1.0ng/mL), good reproducibility and accuracy. The behavior of this material is also being tested in spiked serum samples, and it is expected to exhibited good selectivity for CEA. The biomimetic layer is currently being merged with a photovoltaic cell. The resulting analytical features are re-evaluated by measuring the efficiency of the cell under white LED illumination. Overall, the proposed sensor is a successful approach to the autonomous determination of CEA in POC. The authors acknowledge the financial support of the European Research Council, through Starting Grant 3P’s/ERC (GA 311086). |
LAANA Truta, MGF Sales The potential of artificial antibodies as biosensing devices for monitoring CA15-3 cancer biomarker (Conference) Oral presentation, 7th Graduate Student Symposium on Molecular Imprinting, Porto, Portugal, 2017. @conference{Truta2017, title = {The potential of artificial antibodies as biosensing devices for monitoring CA15-3 cancer biomarker }, author = {LAANA Truta and MGF Sales}, year = {2017}, date = {2017-06-09}, address = {Porto, Portugal}, organization = {Oral presentation, 7th Graduate Student Symposium on Molecular Imprinting,}, abstract = {Cancer diseases are a leading cause of death worldwide, being breast cancer among the most common cancer. Advances in controlling this disease have greatly contributed to its early diagnosis and to monitoring its response during treatment or recurrence. Presently, CA15-3 protein is the circulating biomarker normally used to detect and follow-up breast cancer, making it a potential biomarker to be applied over wide screening programs and in point-of-care (POC) scenarios. Pursuing this goal, new biosensors for CA15-3 are emerging in the literature. This work describes a novel approach for sensing CA15-3 in point-of-care. It consists of a novel artificial antibody, making use of molecularly imprinted polymer (MIP) technology and electropolymerization of O-phenylenediamine. The polymer was tailored on a conductive glass (with fluorine doped tin oxide, FTO) modified with platinum nanoparticles (PtNPs). The analytical performance of the resulting devices was characterized by electrochemical impedance spectroscopy (EIS), showing sensitive readings of CA15-3 concentrations from 1.0x10-5 to 10U/mL in phosphate buffer. Chemical modifications of the surface were characterized using Fourier Transform Infrared (FTIR), and Raman spectroscopy. In conclusion, the devices developed are a promising tool for monitoring the CA15-3 in POC applications, showing linear responses below the normal physiological levels expected, simplicity of manufacture, low-cost and good sensitivity. European Research Council is acknowledged for funding this work through the Starting Grant, ERC-StG-3P’s/2012, GA 311086 (to MGF Sales). }, keywords = {}, pubstate = {published}, tppubtype = {conference} } Cancer diseases are a leading cause of death worldwide, being breast cancer among the most common cancer. Advances in controlling this disease have greatly contributed to its early diagnosis and to monitoring its response during treatment or recurrence. Presently, CA15-3 protein is the circulating biomarker normally used to detect and follow-up breast cancer, making it a potential biomarker to be applied over wide screening programs and in point-of-care (POC) scenarios. Pursuing this goal, new biosensors for CA15-3 are emerging in the literature. This work describes a novel approach for sensing CA15-3 in point-of-care. It consists of a novel artificial antibody, making use of molecularly imprinted polymer (MIP) technology and electropolymerization of O-phenylenediamine. The polymer was tailored on a conductive glass (with fluorine doped tin oxide, FTO) modified with platinum nanoparticles (PtNPs). The analytical performance of the resulting devices was characterized by electrochemical impedance spectroscopy (EIS), showing sensitive readings of CA15-3 concentrations from 1.0x10-5 to 10U/mL in phosphate buffer. Chemical modifications of the surface were characterized using Fourier Transform Infrared (FTIR), and Raman spectroscopy. In conclusion, the devices developed are a promising tool for monitoring the CA15-3 in POC applications, showing linear responses below the normal physiological levels expected, simplicity of manufacture, low-cost and good sensitivity. European Research Council is acknowledged for funding this work through the Starting Grant, ERC-StG-3P’s/2012, GA 311086 (to MGF Sales). |
AR Cardoso, MGF Sales, Electrochemical sensor for azoxicillin detection in aquaculture, 7th Graduate Student Symposium on Molecular Imprinting, Porto, Portugal, 8 e 9 de junho Electrochemical sensor for azoxicillin detection in aquaculture (Conference) 7th Graduate Student Symposium on Molecular Imprinting , Porto, Portugal, 8 e 9 de junho, 2017. (BibTeX) @conference{Cardoso2017, title = { Electrochemical sensor for azoxicillin detection in aquaculture}, author = {AR Cardoso, MGF Sales, Electrochemical sensor for azoxicillin detection in aquaculture, 7th Graduate Student Symposium on Molecular Imprinting, Porto, Portugal, 8 e 9 de junho}, year = {2017}, date = {2017-06-08}, publisher = {7th Graduate Student Symposium on Molecular Imprinting }, address = {Porto, Portugal, 8 e 9 de junho}, keywords = {}, pubstate = {published}, tppubtype = {conference} } |
MS Silva, APM Tavares, MGF Sales, Biomimetic biosensor using myoglobin bulk imprint by electropolymerization Biomimetic biosensor using myoglobin bulk imprint by electropolymerization (Conference) 7th Graduate Student Symposium on Molecular Imprinting , Porto, Portugal, 8 e 9 de junho., 2017. (BibTeX) @conference{Silva2017, title = {Biomimetic biosensor using myoglobin bulk imprint by electropolymerization}, author = {MS Silva, APM Tavares, MGF Sales, Biomimetic biosensor using myoglobin bulk imprint by electropolymerization}, year = {2017}, date = {2017-06-08}, publisher = {7th Graduate Student Symposium on Molecular Imprinting }, address = {Porto, Portugal, 8 e 9 de junho.}, keywords = {}, pubstate = {published}, tppubtype = {conference} } |
L Carneiro, MGF Sales, LR Brandão , Autonomous surface imprinted electrochemical biosensor using SWNH (Conference) 7th Graduate Student Symposium on Molecular Imprinting , Porto, Portugal, 8 e 9 de junho., 2017. (BibTeX) @conference{Carneiro2017, title = {, Autonomous surface imprinted electrochemical biosensor using SWNH}, author = {L Carneiro, MGF Sales, LR Brandão}, year = {2017}, date = {2017-06-08}, publisher = {7th Graduate Student Symposium on Molecular Imprinting }, address = {Porto, Portugal, 8 e 9 de junho.}, keywords = {}, pubstate = {published}, tppubtype = {conference} } |
GV Martins, AC Marques, E Fortunato, MGF Sales, , An imprinted paper-based biosensor designed towards point-of-care diagnosis (Conference) 7th Graduate Student Symposium on Molecular Imprinting , Porto, Portugal, 8 e 9 de junho., 2017. (BibTeX) @conference{Martins2017, title = {An imprinted paper-based biosensor designed towards point-of-care diagnosis}, author = {GV Martins, AC Marques, E Fortunato, MGF Sales, , }, year = {2017}, date = {2017-06-08}, publisher = {7th Graduate Student Symposium on Molecular Imprinting }, address = {Porto, Portugal, 8 e 9 de junho.}, keywords = {}, pubstate = {published}, tppubtype = {conference} } |
2016
MGF Sales Biosensors meet photovoltaics: an innovative biosensing approach (Conference) Invited Presentation (INV6), 26th Anniversary World Congress on Biosensors, Biosensors, Gothenburg, Sweden, 2016. @conference{Sales2016, title = {Biosensors meet photovoltaics: an innovative biosensing approach}, author = {MGF Sales}, year = {2016}, date = {2016-05-26}, address = {Gothenburg, Sweden}, organization = {Invited Presentation (INV6), 26th Anniversary World Congress on Biosensors, Biosensors,}, abstract = {Within the typical long course of cancer diseases, there are several biochemical alterations that may be followed in body fluids, mostly protein materials and other smaller sized metabolites, recognized as cancer biomarkers. Detecting such biomarkers may turn out a valuable tool for screening the disease. But there are few devices described so far for this purpose. Those relying in electrical signals allow highly-sensitive procedures and should be excellent for point-of-care applications. However, they are dependent of an electrical source to operate. Electrical independency of biosensors can be achieved by merging photovoltaics and biosensing technology in a single device, an approach never taken before. In addition, the use of plastic antibodies as biorecognition element yields a highly stable tool, capable of operating anywhere. Such innovative approach has been funded by European Research Council (ERC), through StG-3P’s. 3P’s is currently in action and has developed novel devices that (i) employ plastic antibodies instead of the corresponding natural biomaterials, leading to lower cost/higher stability operations; (ii) merged in photovoltaic cell that confer full autonomy to the electrical device. It has been successfully tested in several cancer biomarkers. These tests include employing different approaches in terms of plastic antibody assembly (chemical and electrical polymerization of conductive and non-conductive materials, with orienting charged-labels) and in its interface with the photovoltaic cell. Overall, the sample is incubated on the plastic antibody tailored on the counter electrode of the photovoltaic cell. Such incubation yields an increased charged-transfer resistance and a subsequent decrease in the electrical output of the cell. Such decrease is in turn correlated with the protein concentration and produces changes in an external material that is electrically dependent and allows visual perception of such alterations. Acknowledgements The author acknowledges the financial support of European Research Council though ERC-2012-StG-311086, GA 311086 (MGF Sales).}, keywords = {}, pubstate = {published}, tppubtype = {conference} } Within the typical long course of cancer diseases, there are several biochemical alterations that may be followed in body fluids, mostly protein materials and other smaller sized metabolites, recognized as cancer biomarkers. Detecting such biomarkers may turn out a valuable tool for screening the disease. But there are few devices described so far for this purpose. Those relying in electrical signals allow highly-sensitive procedures and should be excellent for point-of-care applications. However, they are dependent of an electrical source to operate. Electrical independency of biosensors can be achieved by merging photovoltaics and biosensing technology in a single device, an approach never taken before. In addition, the use of plastic antibodies as biorecognition element yields a highly stable tool, capable of operating anywhere. Such innovative approach has been funded by European Research Council (ERC), through StG-3P’s. 3P’s is currently in action and has developed novel devices that (i) employ plastic antibodies instead of the corresponding natural biomaterials, leading to lower cost/higher stability operations; (ii) merged in photovoltaic cell that confer full autonomy to the electrical device. It has been successfully tested in several cancer biomarkers. These tests include employing different approaches in terms of plastic antibody assembly (chemical and electrical polymerization of conductive and non-conductive materials, with orienting charged-labels) and in its interface with the photovoltaic cell. Overall, the sample is incubated on the plastic antibody tailored on the counter electrode of the photovoltaic cell. Such incubation yields an increased charged-transfer resistance and a subsequent decrease in the electrical output of the cell. Such decrease is in turn correlated with the protein concentration and produces changes in an external material that is electrically dependent and allows visual perception of such alterations. Acknowledgements The author acknowledges the financial support of European Research Council though ERC-2012-StG-311086, GA 311086 (MGF Sales). |
AM Piloto, MF Frasco, SSM Rodrigues, DSM Ribeiro, JLM Santos, MGF Sales Myoglobin imprinted polymer on CdTeMPA quantum dots as a fluorescent biosensor (Conference) Poster (P2.309), 26th Anniversary World Congress on Biosensors, Biosensors, Gothenburg, Sweden, 2016. @conference{Piloto2016, title = {Myoglobin imprinted polymer on CdTeMPA quantum dots as a fluorescent biosensor}, author = {AM Piloto and MF Frasco and SSM Rodrigues and DSM Ribeiro and JLM Santos and MGF Sales}, year = {2016}, date = {2016-05-26}, address = {Gothenburg, Sweden}, organization = {Poster (P2.309), 26th Anniversary World Congress on Biosensors, Biosensors,}, abstract = {A highly sensitive fluorescent sensor was developed for Myoglobin (Myo) cardiac biomarker. In this work, the combination of quantum dots (QDs) with molecular imprinted polymers (MIPs) conciliates the optical amplification readout characteristic of QDs with the sensible recognition capacity from MIPs. The nanostructure MIPs present good stability, improved sensitivity and high selectivity towards Myo. These features prove their potential to be explored as new emerging sensors for Myo detection in synthetic human serum. The LOD achieved (0.56 ng/ml, RSD = 0.26%), is inferior to reported values regarding Myo concentration in human serum for myocardial infarction (9.52 - 47.09) ng/ml.}, keywords = {}, pubstate = {published}, tppubtype = {conference} } A highly sensitive fluorescent sensor was developed for Myoglobin (Myo) cardiac biomarker. In this work, the combination of quantum dots (QDs) with molecular imprinted polymers (MIPs) conciliates the optical amplification readout characteristic of QDs with the sensible recognition capacity from MIPs. The nanostructure MIPs present good stability, improved sensitivity and high selectivity towards Myo. These features prove their potential to be explored as new emerging sensors for Myo detection in synthetic human serum. The LOD achieved (0.56 ng/ml, RSD = 0.26%), is inferior to reported values regarding Myo concentration in human serum for myocardial infarction (9.52 - 47.09) ng/ml. |
C Hora, APM Tavares, A Mendes, MGF Sales Biomimetic material integrated in a conductive polymer powered by a dye-sensitized solar cell (Conference) Oral Presentation (O17), 26th Anniversary World Congress on Biosensors, Biosensors, Gothenburg, Sweden, 2016. @conference{Hora2016b, title = {Biomimetic material integrated in a conductive polymer powered by a dye-sensitized solar cell}, author = {C Hora and APM Tavares and A Mendes and MGF Sales}, year = {2016}, date = {2016-05-25}, address = {Gothenburg, Sweden}, organization = {Oral Presentation (O17), 26th Anniversary World Congress on Biosensors, Biosensors,}, abstract = {A dye sensitized solar cell (DSSC) has a titanium dioxide (TiO2) photoanode with dye adsorbed in the surface, a counter electrode (CE) and an electrolyte in between closing the external circuit. When illuminated, it generates electrical current (Figure 1). A DSSC cell is presented herein for the first time ever as the electrical power and future transducing element of an electrical biosensor, thereby generating a fully autonomous electrical biosensing device. It is applied herein to a cancer biomarker. The TiO2 paste is deposited in the fluorine transparent oxide (FTO) coated glass, imprinted in a circular area of 0.2cm2, and annealed at 450°C for 30min, to be later immersed in dye solution. The CE is an FTO glass coated with PEDOT, by electropolymerization of EDOT at 0.9V within 240–920s. A molecularly imprinted polymer (MIP) for a protein cancer biomarker is tailored on the PEDOT layer by polymerization of EDOT and Pyrrole, using cyclic voltammetry at -0.3V to 0.95V. The resulting DSSCs electrical properties are characterized with linear-sweep voltammetry scanning from 0.8–0V at a rate of 1.5mV/s under 100±10W/cm2 illumination. Electrochemical impedance spectroscopy (EIS) is used to characterize the DSSC at 0.75V under illumination, with a frequency range of 0.005Hz–100kHz. Overall, the impact of the electropolymerization timing on the efficiency of the cell and its stability is clear. The assembly of the MIP layer on the PEDOT film of the CE produces a decrease on the recorded efficiency. The incubation of the protein biomarker on this CE yields and additional efficiency decrease. Such decrease is controlled by the protein concentration and complies with the reference concentration in serum. Acknowledgments The authors acknowledge the financial support of European Research Council though ERC-2012-StG-311086 GA no. 311086 (MGF Sales).}, keywords = {}, pubstate = {published}, tppubtype = {conference} } A dye sensitized solar cell (DSSC) has a titanium dioxide (TiO2) photoanode with dye adsorbed in the surface, a counter electrode (CE) and an electrolyte in between closing the external circuit. When illuminated, it generates electrical current (Figure 1). A DSSC cell is presented herein for the first time ever as the electrical power and future transducing element of an electrical biosensor, thereby generating a fully autonomous electrical biosensing device. It is applied herein to a cancer biomarker. The TiO2 paste is deposited in the fluorine transparent oxide (FTO) coated glass, imprinted in a circular area of 0.2cm2, and annealed at 450°C for 30min, to be later immersed in dye solution. The CE is an FTO glass coated with PEDOT, by electropolymerization of EDOT at 0.9V within 240–920s. A molecularly imprinted polymer (MIP) for a protein cancer biomarker is tailored on the PEDOT layer by polymerization of EDOT and Pyrrole, using cyclic voltammetry at -0.3V to 0.95V. The resulting DSSCs electrical properties are characterized with linear-sweep voltammetry scanning from 0.8–0V at a rate of 1.5mV/s under 100±10W/cm2 illumination. Electrochemical impedance spectroscopy (EIS) is used to characterize the DSSC at 0.75V under illumination, with a frequency range of 0.005Hz–100kHz. Overall, the impact of the electropolymerization timing on the efficiency of the cell and its stability is clear. The assembly of the MIP layer on the PEDOT film of the CE produces a decrease on the recorded efficiency. The incubation of the protein biomarker on this CE yields and additional efficiency decrease. Such decrease is controlled by the protein concentration and complies with the reference concentration in serum. Acknowledgments The authors acknowledge the financial support of European Research Council though ERC-2012-StG-311086 GA no. 311086 (MGF Sales). |
APM Tavares, MGF Sales A novel antibody-like material assembled on novel screen-printed electrodes for screening CEA cancer biomarker (Conference) Poster (P2.306), 26th Anniversary World Congress on Biosensors, Biosensors, Gothenburg, Sweden, 2016. @conference{Tavares2016b, title = {A novel antibody-like material assembled on novel screen-printed electrodes for screening CEA cancer biomarker}, author = {APM Tavares and MGF Sales }, year = {2016}, date = {2016-05-25}, address = {Gothenburg, Sweden}, organization = {Poster (P2.306), 26th Anniversary World Congress on Biosensors, Biosensors,}, abstract = {Carcino-Embryonic Antigen (CEA) is a tumour biomarker in colorectal cancer. Its routine determination is important for long-term survival of cancer patients. There are few procedures to determine CEA in point-of-care. Some approaches make use of antibodies, reproducing ELISA methods on a biosensing platform. But antibodies are unstable and very expensive for screening programs, among other disadvantages. Other approaches use screen-printed electrodes (SPEs) that are not prepared for worldwide applications, as the device is unstable or environmentally unsuitable to be discarded. Thus, this work describes the combination of a biomimetic polymer for CEA, acting as a natural antibody (Figure 1), combined with a novel SPE design, made on a low cost and electrically/chemically stable material and natural support. The antibody-like material made use of molecularly-imprinted polymer (MIP) technology, prepared by co-electro-polymerizing EDOT and pyrrole (PY) by cyclic voltammetry (CV), from -0.3 to +0.95V (vs. Ag/AgCl) with different cycling numbers: 8 (MIP-8) and 10 (MIP-10).The obtained sensors were characterized by Electrochemical Impedance Spectroscopy (EIS), in Phospate buffer saline (PBS). Raman spectroscopy confirmed all stages of the surface modification. Both materials displayed linear responses over a wide range of concentrations, good reproducibility and accuracy. MIP-8 devices showed a linear response down-to 0.1ng/mL and slopes of +3.03 Ω/decade; MIP-10 had a linear behaviour down-to 5ng/mL and a slope of +2.80 Ω/decade. The behavior of both materials was further tested in spiked serum samples, exhibiting good selectivity for CEA. The proposed sensors are a successful approach for the determination of CEA in point-of-care, currently transposed to cork-based devices, where additional promising features are displayed due to the hydrophobic nature and physical stability of the support. Acknowledgments The authors acknowledge the financial support of European Research Council though ERC- 2012-StG-311086 GA no. 311086 (MGF Sales).}, keywords = {}, pubstate = {published}, tppubtype = {conference} } Carcino-Embryonic Antigen (CEA) is a tumour biomarker in colorectal cancer. Its routine determination is important for long-term survival of cancer patients. There are few procedures to determine CEA in point-of-care. Some approaches make use of antibodies, reproducing ELISA methods on a biosensing platform. But antibodies are unstable and very expensive for screening programs, among other disadvantages. Other approaches use screen-printed electrodes (SPEs) that are not prepared for worldwide applications, as the device is unstable or environmentally unsuitable to be discarded. Thus, this work describes the combination of a biomimetic polymer for CEA, acting as a natural antibody (Figure 1), combined with a novel SPE design, made on a low cost and electrically/chemically stable material and natural support. The antibody-like material made use of molecularly-imprinted polymer (MIP) technology, prepared by co-electro-polymerizing EDOT and pyrrole (PY) by cyclic voltammetry (CV), from -0.3 to +0.95V (vs. Ag/AgCl) with different cycling numbers: 8 (MIP-8) and 10 (MIP-10).The obtained sensors were characterized by Electrochemical Impedance Spectroscopy (EIS), in Phospate buffer saline (PBS). Raman spectroscopy confirmed all stages of the surface modification. Both materials displayed linear responses over a wide range of concentrations, good reproducibility and accuracy. MIP-8 devices showed a linear response down-to 0.1ng/mL and slopes of +3.03 Ω/decade; MIP-10 had a linear behaviour down-to 5ng/mL and a slope of +2.80 Ω/decade. The behavior of both materials was further tested in spiked serum samples, exhibiting good selectivity for CEA. The proposed sensors are a successful approach for the determination of CEA in point-of-care, currently transposed to cork-based devices, where additional promising features are displayed due to the hydrophobic nature and physical stability of the support. Acknowledgments The authors acknowledge the financial support of European Research Council though ERC- 2012-StG-311086 GA no. 311086 (MGF Sales). |
L Brandão, MGF Sales, MHM Sá, NS Ferreira, LPT Carneiro Development of autonomous electrochemical biosensors - The Symbiotic project (Conference) Oral Presentation (O29), 26th Anniversary World Congress on Biosensors, Biosensors, Gothenburg, Sweden, 2016. @conference{Brandão2016, title = {Development of autonomous electrochemical biosensors - The Symbiotic project}, author = {L Brandão and MGF Sales and MHM Sá and NS Ferreira and LPT Carneiro}, year = {2016}, date = {2016-05-25}, address = {Gothenburg, Sweden}, organization = {Oral Presentation (O29), 26th Anniversary World Congress on Biosensors, Biosensors,}, abstract = {This summary addresses the development of innovative biosensors for early detection of cancer. Autonomous electrochemical biosensors that are lightweight, disposable and low cost are being developed by a radically new approach: hosting synergistically a biommimetic bioreceptor element inside a passive direct methanol fuel cell (DMFC). Such approach provides an electrically independent, very simple, miniaturized, autonomous biosensor. The electrical dependency is eliminated by coupling the biosensor to an electrochemical transducer that is capable of energy production, the fuel cell. In this envisaged innovative device, the electrical signal obtained from the DMFC is directly related to the concentration of the cancer biomarker in the sample analyzed. This proposed electrochemical biosensor is completely autonomous operating at room temperature and using the oxygen present in the air, thereby allowing diagnosis everywhere what can promote a high impact on point-of care technologies. A highly interdisciplinary approach is being used by merging the knowledge from several fields of science: biochemistry, electrochemistry, polymer science, nanotechnology, and chemical engineering applied to the biosensors and energy areas. For that, this work accounts on partners such as ISEP (Portugal) that is developing molecularly imprinted polymers, Imperial College of London (UK) and VTT (Finland), working on low cost designs for passive DFMC with high energetic efficiency, UNINOVA (Portugal) developing a low cost signalling interface compactly integrated in the autonomous biosensor using electrochromic technologies, and Aarhus University (Denmark) that is studying the biochemical interactions between proteins and the biosensor area. The approach presented herein has been recently funded with an EU grant from the Horizon 2020 program – Symbiotic (www.symbiotic-project.eu), in a FET-OPEN call of the Pillar of Excellence (I) which has started on June 2015. The developments achieved will be presented by highlighting the main results obtained in the first year of execution of the Symbiotic project.}, keywords = {}, pubstate = {published}, tppubtype = {conference} } This summary addresses the development of innovative biosensors for early detection of cancer. Autonomous electrochemical biosensors that are lightweight, disposable and low cost are being developed by a radically new approach: hosting synergistically a biommimetic bioreceptor element inside a passive direct methanol fuel cell (DMFC). Such approach provides an electrically independent, very simple, miniaturized, autonomous biosensor. The electrical dependency is eliminated by coupling the biosensor to an electrochemical transducer that is capable of energy production, the fuel cell. In this envisaged innovative device, the electrical signal obtained from the DMFC is directly related to the concentration of the cancer biomarker in the sample analyzed. This proposed electrochemical biosensor is completely autonomous operating at room temperature and using the oxygen present in the air, thereby allowing diagnosis everywhere what can promote a high impact on point-of care technologies. A highly interdisciplinary approach is being used by merging the knowledge from several fields of science: biochemistry, electrochemistry, polymer science, nanotechnology, and chemical engineering applied to the biosensors and energy areas. For that, this work accounts on partners such as ISEP (Portugal) that is developing molecularly imprinted polymers, Imperial College of London (UK) and VTT (Finland), working on low cost designs for passive DFMC with high energetic efficiency, UNINOVA (Portugal) developing a low cost signalling interface compactly integrated in the autonomous biosensor using electrochromic technologies, and Aarhus University (Denmark) that is studying the biochemical interactions between proteins and the biosensor area. The approach presented herein has been recently funded with an EU grant from the Horizon 2020 program – Symbiotic (www.symbiotic-project.eu), in a FET-OPEN call of the Pillar of Excellence (I) which has started on June 2015. The developments achieved will be presented by highlighting the main results obtained in the first year of execution of the Symbiotic project. |
AR Khan, AR Cardoso, S Merino, J Riu, MGF Sales Plastic antibody for the electrochemical detection of bacterial flagella (Conference) Poster (P1.271), 26th Anniversary World Congress on Biosensors, Biosensors, Gothenburg, Sweden, 2016. (BibTeX) @conference{Khan2016b, title = {Plastic antibody for the electrochemical detection of bacterial flagella}, author = {AR Khan and AR Cardoso and S Merino and J Riu and MGF Sales}, year = {2016}, date = {2016-05-25}, address = {Gothenburg, Sweden}, organization = {Poster (P1.271), 26th Anniversary World Congress on Biosensors, Biosensors,}, keywords = {}, pubstate = {published}, tppubtype = {conference} } |
FTC Moreira, MGF Sales Smart naturally plastic antibody based on α-poly-cyclodextrin polymer for β-amyloid42 soluble oligomer (Conference) Poster (P1.268), 26th Anniversary World Congress on Biosensors, Biosensors, Gothenburg, Sweden, 2016. (BibTeX) @conference{Moreira2016b, title = {Smart naturally plastic antibody based on α-poly-cyclodextrin polymer for β-amyloid42 soluble oligomer}, author = {FTC Moreira and MGF Sales}, year = {2016}, date = {2016-05-25}, address = {Gothenburg, Sweden}, organization = {Poster (P1.268), 26th Anniversary World Congress on Biosensors, Biosensors,}, keywords = {}, pubstate = {published}, tppubtype = {conference} } |
C Hora, LAANA Truta, APM Tavares, MF Frasco, AM Piloto, MGF Sales Integrating biosensors in photovoltaic cells: the 3P’s project (Conference) Poster, International Biomedical Engineering Meeting, ESTSP, Biblioteca de Almeida Garrett, Porto, Portugal, 2016. @conference{Hora2016b, title = {Integrating biosensors in photovoltaic cells: the 3P’s project}, author = {C Hora and LAANA Truta and APM Tavares and MF Frasco and AM Piloto and MGF Sales}, year = {2016}, date = {2016-03-21}, address = {Biblioteca de Almeida Garrett, Porto, Portugal}, organization = {Poster, International Biomedical Engineering Meeting, ESTSP,}, abstract = {The overall concept is the development of a point-of-care device that merges the sensing layer of a biosensor assembled in a photovoltaic cell. The sensing materials rely on the selectivity of plastic antibodies tailored for specific proteins that act as cancer biomarkers. Once this layer contacts with a real sample, the specific protein binds to the plastic antibody material. The photovoltaic cell is then set-up and the electrical output measured, which will change proportionally to the interference generated by the amount of bounded protein biomarker. As photovoltaic cell, a dye-sensitized solar cell (DSSC) is used. It is composed by two electrodes, the photoanode and the cathode. These are separated by the electrolyte, which completes the external circuit. The photoanode has a semiconductor and a dye anchored on it; the dye absorbs photons, becomes excited and injects electrons into the semiconductor, thereby generating electrical current. The dye may be replaced by quantum dots (QDs), capable of enhancing light absorption and improving the efficiency of photovoltaic cells. The cathode is typically composed by platinum as catalytic material, but it may also be replaced by less expensive conductive polymers. Herein, two approaches are pursued to assemble a cathode that may support the plastic antibody: one where platinum nanoparticles are modified and another where PEDOT is used as conductive polymer due to its good thermal and electrochemical stability, as well as high conductivity. In order to assemble the plastic antibody on the photoanode, the dye is also replaced by QDs with an imprinted layer on it. Overall, several of the above approaches are followed to determine interleukin-2, CEA, and CA15-3, as cancer biomarkers, all integrated in a single, compact and soon autonomous device. Such devices display currently extensive linear responses, over sensitive concentration ranges. Further studies are progressing within the different approaches described herein, which are ultimately meant to merge Plastic Antibodies, Plasmonics and Photovoltaics (3P’s) in a single autonomous apparatus.}, keywords = {}, pubstate = {published}, tppubtype = {conference} } The overall concept is the development of a point-of-care device that merges the sensing layer of a biosensor assembled in a photovoltaic cell. The sensing materials rely on the selectivity of plastic antibodies tailored for specific proteins that act as cancer biomarkers. Once this layer contacts with a real sample, the specific protein binds to the plastic antibody material. The photovoltaic cell is then set-up and the electrical output measured, which will change proportionally to the interference generated by the amount of bounded protein biomarker. As photovoltaic cell, a dye-sensitized solar cell (DSSC) is used. It is composed by two electrodes, the photoanode and the cathode. These are separated by the electrolyte, which completes the external circuit. The photoanode has a semiconductor and a dye anchored on it; the dye absorbs photons, becomes excited and injects electrons into the semiconductor, thereby generating electrical current. The dye may be replaced by quantum dots (QDs), capable of enhancing light absorption and improving the efficiency of photovoltaic cells. The cathode is typically composed by platinum as catalytic material, but it may also be replaced by less expensive conductive polymers. Herein, two approaches are pursued to assemble a cathode that may support the plastic antibody: one where platinum nanoparticles are modified and another where PEDOT is used as conductive polymer due to its good thermal and electrochemical stability, as well as high conductivity. In order to assemble the plastic antibody on the photoanode, the dye is also replaced by QDs with an imprinted layer on it. Overall, several of the above approaches are followed to determine interleukin-2, CEA, and CA15-3, as cancer biomarkers, all integrated in a single, compact and soon autonomous device. Such devices display currently extensive linear responses, over sensitive concentration ranges. Further studies are progressing within the different approaches described herein, which are ultimately meant to merge Plastic Antibodies, Plasmonics and Photovoltaics (3P’s) in a single autonomous apparatus. |
ART Santos, MGF Sales Novel biosensor employing a plastic antibody as recognition element for CEA detection (Conference) Poster, International Biomedical Engineering Meeting, ESTSP, Biblioteca de Almeida Garrett, Porto, Portugal, 2016. @conference{Santos2016, title = {Novel biosensor employing a plastic antibody as recognition element for CEA detection}, author = {ART Santos and MGF Sales }, year = {2016}, date = {2016-03-21}, address = {Biblioteca de Almeida Garrett, Porto, Portugal}, organization = {Poster, International Biomedical Engineering Meeting, ESTSP,}, abstract = {Biosensors may replace the current ELISA techniques used in health care centres to track many biomolecules, with subsequent advantages in terms of cost, time and portability. In general, a biosensor consists of two parts: a biorecognition element and a transducer. The biorecognition element contains a biomolecule that is able to interact specifically with a given target analyte, while the transducer converts such interaction into a measurable signal. The use of a screen-printed electrode format may further allow the use of less than 20 μL of sample, opening doors towards point-of-care applications. In turn, the determination of carcinoembryonic antigen (CEA) in serum and in point-of-care context is highly desired. CEA is overexpressed in most human serum adenocarcinomas, including colorectal, pancreatic and breast cancers. Many techniques have been developed for monitoring CEA, most of these immobilizing antibodies on suitable supports. The interaction between Anti-CEA and CEA generates a signal change, that is correlated to CEA concentration in the sample. The antibodies are the ones responsible for the selectivity of the device, but these biomaterials are very expensive and offer little stability. For this, plastic antibodies produced by a molecularly-imprinting polymer (MIP) approach may replace the use of natural antibodies in this context. MIP technique engraves 3D cavities on a polymeric substrate that hold the same size, shape and orientation of a target protein and that eventually act as natural antibodies. In this work, a biosensor for CEA using plastic antibody as recognition element and conductive glass as substrate is proposed. The conductive glass was first covered by electropolymerized EDOT. Then, the MIP layer was assembled by surface imprinting of PEDOT with CEA previously incubated on methylene blue (MB). The imprinted films were deposited by chronoamperometry at 0.9V vs Ag/AgCl. The chemical modification of the polymeric layer was characterized by RAMAN spectroscopy. Overall, the MIP layer had a good stability and good linear response at pH 7.4 and the RAMAN evidenced successful surface modification. A control polymer without imprinted CEA showed random response against the protein. The biomimetic sensor is following further investigation and seems a promising approach for the determination of CEA in point-of-care.}, keywords = {}, pubstate = {published}, tppubtype = {conference} } Biosensors may replace the current ELISA techniques used in health care centres to track many biomolecules, with subsequent advantages in terms of cost, time and portability. In general, a biosensor consists of two parts: a biorecognition element and a transducer. The biorecognition element contains a biomolecule that is able to interact specifically with a given target analyte, while the transducer converts such interaction into a measurable signal. The use of a screen-printed electrode format may further allow the use of less than 20 μL of sample, opening doors towards point-of-care applications. In turn, the determination of carcinoembryonic antigen (CEA) in serum and in point-of-care context is highly desired. CEA is overexpressed in most human serum adenocarcinomas, including colorectal, pancreatic and breast cancers. Many techniques have been developed for monitoring CEA, most of these immobilizing antibodies on suitable supports. The interaction between Anti-CEA and CEA generates a signal change, that is correlated to CEA concentration in the sample. The antibodies are the ones responsible for the selectivity of the device, but these biomaterials are very expensive and offer little stability. For this, plastic antibodies produced by a molecularly-imprinting polymer (MIP) approach may replace the use of natural antibodies in this context. MIP technique engraves 3D cavities on a polymeric substrate that hold the same size, shape and orientation of a target protein and that eventually act as natural antibodies. In this work, a biosensor for CEA using plastic antibody as recognition element and conductive glass as substrate is proposed. The conductive glass was first covered by electropolymerized EDOT. Then, the MIP layer was assembled by surface imprinting of PEDOT with CEA previously incubated on methylene blue (MB). The imprinted films were deposited by chronoamperometry at 0.9V vs Ag/AgCl. The chemical modification of the polymeric layer was characterized by RAMAN spectroscopy. Overall, the MIP layer had a good stability and good linear response at pH 7.4 and the RAMAN evidenced successful surface modification. A control polymer without imprinted CEA showed random response against the protein. The biomimetic sensor is following further investigation and seems a promising approach for the determination of CEA in point-of-care. |
AM Gomes, APM Tavares, MGF Sales A molecularly imprinted polymer for detection glutamic acid (Conference) Poster, International Biomedical Engineering Meeting, ESTSP, Biblioteca de Almeida Garrett, Porto, Portugal, 2016. @conference{Gomes2016b, title = {A molecularly imprinted polymer for detection glutamic acid}, author = {AM Gomes and APM Tavares and MGF Sales }, year = {2016}, date = {2016-03-21}, address = {Biblioteca de Almeida Garrett, Porto, Portugal}, organization = {Poster, International Biomedical Engineering Meeting, ESTSP,}, abstract = {Glutamic acid (GLU) is a very important neurotransmitter in the central nervous system and a non-essential amino acid. In terms of metabolism, GLU is converted by glutamine synthetase into glutamine. This molecule is not synthesized in neoplasic cells because glutamine synthetase has lower reactivity in healthy cells. Thus, an antagonist of this enzyme interferes with the metabolism of glutamine and can be considered an anti-cancer agent. This molecule has great utility in lowering blood pressure and it is very important in memory retention. The increase of the concentration of glutamic acid may be associated to some diseases like amyotrophic lateral sclerosis or Alzheimer. Thus, it is important to develop a biosensor capable of detecting GLU in clinical context. This work describes for this purpose a biomimetic sensor for GLU, based on molecularly imprinted polymer (MIP) technology, established by bulk polymerization. The reaction combines acrylamide and bis-acrylamide in the presence of GLU. After polymerization, GLU is removed from polymeric matrix by suitable reaction. The rebinding of GLU to the imprinted material was followed by potentiometric transduction mode and the analytical data collected used for quantitative purposes. The presence of GLU in the polymeric matrix was confirmed by performing qualitative studies based in Fourier Transform Spectroscopy (FTIR), Scanning Electron Microscope (SEM) coupled to Spectroscopy X-ray Dispersive Energy (EDS), and thermalgravimetry (TG). The developed materials were used to prepare various selective membranes of different compositions, using an old 100μL micropipette tip as electrode body and an Ag wire covered by AgCl as inner reference electrode. The inner reference composition is a critical parameter of the overall potentiometric device. The recording of several calibration curves confirmed that a good GLU selective membrane contained 5% of MIP material and p-tert-octylphenol (pTop) as lipophilic additive. The analytical response of the device indicated average slopes of about 28.52 mV/decade, over the concentration range 1.6×10-6 to 1.5×10-3 mol/L, when tested in real urine samples.}, keywords = {}, pubstate = {published}, tppubtype = {conference} } Glutamic acid (GLU) is a very important neurotransmitter in the central nervous system and a non-essential amino acid. In terms of metabolism, GLU is converted by glutamine synthetase into glutamine. This molecule is not synthesized in neoplasic cells because glutamine synthetase has lower reactivity in healthy cells. Thus, an antagonist of this enzyme interferes with the metabolism of glutamine and can be considered an anti-cancer agent. This molecule has great utility in lowering blood pressure and it is very important in memory retention. The increase of the concentration of glutamic acid may be associated to some diseases like amyotrophic lateral sclerosis or Alzheimer. Thus, it is important to develop a biosensor capable of detecting GLU in clinical context. This work describes for this purpose a biomimetic sensor for GLU, based on molecularly imprinted polymer (MIP) technology, established by bulk polymerization. The reaction combines acrylamide and bis-acrylamide in the presence of GLU. After polymerization, GLU is removed from polymeric matrix by suitable reaction. The rebinding of GLU to the imprinted material was followed by potentiometric transduction mode and the analytical data collected used for quantitative purposes. The presence of GLU in the polymeric matrix was confirmed by performing qualitative studies based in Fourier Transform Spectroscopy (FTIR), Scanning Electron Microscope (SEM) coupled to Spectroscopy X-ray Dispersive Energy (EDS), and thermalgravimetry (TG). The developed materials were used to prepare various selective membranes of different compositions, using an old 100μL micropipette tip as electrode body and an Ag wire covered by AgCl as inner reference electrode. The inner reference composition is a critical parameter of the overall potentiometric device. The recording of several calibration curves confirmed that a good GLU selective membrane contained 5% of MIP material and p-tert-octylphenol (pTop) as lipophilic additive. The analytical response of the device indicated average slopes of about 28.52 mV/decade, over the concentration range 1.6×10-6 to 1.5×10-3 mol/L, when tested in real urine samples. |
AIFL Silva, HIAS Gomes, MGF Sales Cellulose derivate modified to produce a rapid colour test for on-site chlortetracycline detection in aquatic environment (Conference) Poster, International Biomedical Engineering Meeting, ESTSP, Biblioteca de Almeida Garrett, Porto, Portugal, 2016. @conference{Silva2016b, title = {Cellulose derivate modified to produce a rapid colour test for on-site chlortetracycline detection in aquatic environment}, author = {AIFL Silva and HIAS Gomes and MGF Sales }, year = {2016}, date = {2016-03-21}, address = {Biblioteca de Almeida Garrett, Porto, Portugal}, organization = {Poster, International Biomedical Engineering Meeting, ESTSP,}, abstract = {While fish products consumption is growing, mainly because it is considered to be healthy and an important source of protein and other essential nutrients1, the capture of wild fish is not sufficient to comply with human’s needs in this regard. Viable economic and environmental measures include aquaculture, which is currently one of the fastest growing food-production sectors. However, intensive farming of fish inside small tanks has led to the appearance of diseases that need drug control2. In this context, antibiotics are commonly used is aquaculture, posing increased concerns in public health. The extensive/intensive use of antibiotics in aquaculture systems has led to the appearance of resistant microbial species, and should be avoided, or if possible, minimized. As antibiotics are necessary to ensure fish survival, only a very strict control of the amount of drug administered into the fish tank may control or reduce antibiotic spread. For this, a simple and inexpensive method, for on-site drug control is required3. The main goal of this work is to develop a sensor for drug detection in aquatic environment, using a low-cost material never tested before. The overall analytical procedure is similar to pH monitoring, by universal pH paper. By binding a metal that can change the colour of the material, after its modification, in the presence of the antibiotic, then color intensity will be related to the antibiotic concentration. In this study, chlortetracycline is targeted, which is among the most frequently used antibiotics in aquaculture activities. The modification was based on chemical change of the glucose units present in the material by a specific amine covalent binding. These modifications were followed and evaluated by Raman spectroscopy and FTIR, and then optimized. In a general way, this work provides a simple and effective procedure for drug detection in aquaculture waters, using a low-cost material. This sensor can be used in point-of-care, so the concentration of antibiotics can be controlled and minimized.}, keywords = {}, pubstate = {published}, tppubtype = {conference} } While fish products consumption is growing, mainly because it is considered to be healthy and an important source of protein and other essential nutrients1, the capture of wild fish is not sufficient to comply with human’s needs in this regard. Viable economic and environmental measures include aquaculture, which is currently one of the fastest growing food-production sectors. However, intensive farming of fish inside small tanks has led to the appearance of diseases that need drug control2. In this context, antibiotics are commonly used is aquaculture, posing increased concerns in public health. The extensive/intensive use of antibiotics in aquaculture systems has led to the appearance of resistant microbial species, and should be avoided, or if possible, minimized. As antibiotics are necessary to ensure fish survival, only a very strict control of the amount of drug administered into the fish tank may control or reduce antibiotic spread. For this, a simple and inexpensive method, for on-site drug control is required3. The main goal of this work is to develop a sensor for drug detection in aquatic environment, using a low-cost material never tested before. The overall analytical procedure is similar to pH monitoring, by universal pH paper. By binding a metal that can change the colour of the material, after its modification, in the presence of the antibiotic, then color intensity will be related to the antibiotic concentration. In this study, chlortetracycline is targeted, which is among the most frequently used antibiotics in aquaculture activities. The modification was based on chemical change of the glucose units present in the material by a specific amine covalent binding. These modifications were followed and evaluated by Raman spectroscopy and FTIR, and then optimized. In a general way, this work provides a simple and effective procedure for drug detection in aquaculture waters, using a low-cost material. This sensor can be used in point-of-care, so the concentration of antibiotics can be controlled and minimized. |
C Ribeiro, R Fernandes, FTC Moreira, MGF Sales Potentiometric sensor for Alzheimer disease diagnosis in point-of-care (Conference) Poster, International Biomedical Engineering Meeting, ESTSP, Biblioteca de Almeida Garrett, Porto, Portugal, 2016. @conference{Ribeiro2016b, title = {Potentiometric sensor for Alzheimer disease diagnosis in point-of-care}, author = {C Ribeiro and R Fernandes and FTC Moreira and MGF Sales}, year = {2016}, date = {2016-03-21}, address = {Biblioteca de Almeida Garrett, Porto, Portugal}, organization = {Poster, International Biomedical Engineering Meeting, ESTSP,}, abstract = {Introduction The majority of people with Dementia have Alzheimer’s disease (AD). AD has systemic signs caused by molecular changes within the disease progression, acting as potential biomarkers. These include mostly Amyloid-β and Tau proteins (total and phosphorylated) in cerebrospinal fluid and plasma. This research presents the development of a newly sensor device for the diagnosis of AD in point-of-care, made with new synthetic biomimetic materials that were incorporated in plasticized poly(vinyl chloride), PVC, membranes, for subsequent potentiometric detection. This concept was applied to target a conventional biomarker in Alzheimer diagnosis: beta amyloid 42 (Aβ-42). Material and Methods The biomimetic material was designed by attaching the peptide Aβ-42 to a surface of carbon nanotubes, and filling the vacant spaces by polymerizing acrylamide (monomer), N,N′-methylenebisacrylamide (cross-linker) and ammonium persulphate (initiator), under mild conditions. The template was removed by protheolitic action of an enzyme (Proteinase K). The biomimetic material was dispersed in plasticized PVC membranes, including or not a lipophilic ionic additive, and applied on a solid conductive support made of graphite. The morphological analysis of materials was evaluated by RAMAN and Fourier Transform Infrared (FTIR) spectroscopies. Results and Discussion The analytical behaviour was evaluated first in buffer and later in human serum. The best analytical performance in buffer was obtained with membranes including biomimetic material and lipophilic cationic additive, tetra-n-octylammonium bromide. The average limits of detection were e 0.72 μg/mL and slope of 59,04 mV/decade. The biosensor was successful applied in human serum samples.}, keywords = {}, pubstate = {published}, tppubtype = {conference} } Introduction The majority of people with Dementia have Alzheimer’s disease (AD). AD has systemic signs caused by molecular changes within the disease progression, acting as potential biomarkers. These include mostly Amyloid-β and Tau proteins (total and phosphorylated) in cerebrospinal fluid and plasma. This research presents the development of a newly sensor device for the diagnosis of AD in point-of-care, made with new synthetic biomimetic materials that were incorporated in plasticized poly(vinyl chloride), PVC, membranes, for subsequent potentiometric detection. This concept was applied to target a conventional biomarker in Alzheimer diagnosis: beta amyloid 42 (Aβ-42). Material and Methods The biomimetic material was designed by attaching the peptide Aβ-42 to a surface of carbon nanotubes, and filling the vacant spaces by polymerizing acrylamide (monomer), N,N′-methylenebisacrylamide (cross-linker) and ammonium persulphate (initiator), under mild conditions. The template was removed by protheolitic action of an enzyme (Proteinase K). The biomimetic material was dispersed in plasticized PVC membranes, including or not a lipophilic ionic additive, and applied on a solid conductive support made of graphite. The morphological analysis of materials was evaluated by RAMAN and Fourier Transform Infrared (FTIR) spectroscopies. Results and Discussion The analytical behaviour was evaluated first in buffer and later in human serum. The best analytical performance in buffer was obtained with membranes including biomimetic material and lipophilic cationic additive, tetra-n-octylammonium bromide. The average limits of detection were e 0.72 μg/mL and slope of 59,04 mV/decade. The biosensor was successful applied in human serum samples. |
FAM Marques, HIAS Gomes, MGF Sales Development of cellulose-based colorimetric sensors to monitor Tetracycline in Aquaculture (Conference) Poster, International Biomedical Engineering Meeting, ESTSP, Biblioteca de Almeida Garrett, Porto, Portugal, 2016. @conference{Marques2016, title = {Development of cellulose-based colorimetric sensors to monitor Tetracycline in Aquaculture}, author = {FAM Marques and HIAS Gomes and MGF Sales }, year = {2016}, date = {2016-03-21}, address = {Biblioteca de Almeida Garrett, Porto, Portugal}, organization = {Poster, International Biomedical Engineering Meeting, ESTSP,}, abstract = {The use of antibiotics in aquaculture has contributed to the appearance of resistant strains, which translates into a high concern with regard to public health and the surrounding ecosystem. The control of antibiotic doses applied in this sector should be a priority to minimizing its environmental effects. This strict control is only possible if the entire analytical process of detection is cheap and allows onsite applications. This could be done by suitable modification of paper-test strips, allowing to generate an indicating paper for finding the antibiotic content in waters. Tetracycline was selected herein as target antibiotic, as it is among the most widely used antibiotics in aquaculture systems. The paper is modified by establishing suitable chemical changes upon cellulose, attributing the paper the ability to react with the organic drug and to produce a colour change. The amination was used for chemical modification and several variables were optimized to obtain an increased sensitivity, namely amine concentration, metal concentration and time given for the amination reaction. Overall, the resulting sensing papers changed colour after contacting with tetracycline. The colour change was evaluated by visual comparison and recorded by a digital image. Quantitative data were treated mathematically by analysing the colour coordinates of the sensors by the HSL system using the Windows Paint® program. The observed staining intensity varied according to the concentration of the drug, ranging from 5.0×10-9 to 1.0×10-2 mol/L. In addition, the described sensor allowed the determination of tetracycline on-site, by a simple paper strip, of low cost and easy production.}, keywords = {}, pubstate = {published}, tppubtype = {conference} } The use of antibiotics in aquaculture has contributed to the appearance of resistant strains, which translates into a high concern with regard to public health and the surrounding ecosystem. The control of antibiotic doses applied in this sector should be a priority to minimizing its environmental effects. This strict control is only possible if the entire analytical process of detection is cheap and allows onsite applications. This could be done by suitable modification of paper-test strips, allowing to generate an indicating paper for finding the antibiotic content in waters. Tetracycline was selected herein as target antibiotic, as it is among the most widely used antibiotics in aquaculture systems. The paper is modified by establishing suitable chemical changes upon cellulose, attributing the paper the ability to react with the organic drug and to produce a colour change. The amination was used for chemical modification and several variables were optimized to obtain an increased sensitivity, namely amine concentration, metal concentration and time given for the amination reaction. Overall, the resulting sensing papers changed colour after contacting with tetracycline. The colour change was evaluated by visual comparison and recorded by a digital image. Quantitative data were treated mathematically by analysing the colour coordinates of the sensors by the HSL system using the Windows Paint® program. The observed staining intensity varied according to the concentration of the drug, ranging from 5.0×10-9 to 1.0×10-2 mol/L. In addition, the described sensor allowed the determination of tetracycline on-site, by a simple paper strip, of low cost and easy production. |
GV Martins, AC Marques, E Fortunato, HR Fernandes, MGF Sales Carbon-based electrodes on paper substrates for biosensing purposes (Conference) Poster, International Biomedical Engineering Meeting, ESTSP, Biblioteca de Almeida Garrett, Porto, Portugal, 2016. @conference{Martins2016b, title = {Carbon-based electrodes on paper substrates for biosensing purposes}, author = {GV Martins and AC Marques and E Fortunato and HR Fernandes and MGF Sales }, year = {2016}, date = {2016-03-21}, address = {Biblioteca de Almeida Garrett, Porto, Portugal}, organization = {Poster, International Biomedical Engineering Meeting, ESTSP,}, abstract = {In the medicine context, early and accurate diagnosis is a crucial step for successful prevention and efficient therapeutic strategies. Further, the development of new methodologies for detection and quantification of Oxidative Stress (OS) biomarkers in point-of-care constitutes an urgent tool in cancer treatment and survival. Over the last years, paper has become an attractive platform for sensors and biomedical devices due to its portability, low-cost, simplicity and easy to operate modus. Here, our main goal is the assembly of carbon-based electrodes using paper substrate for electrochemical analysis of OS biomarkers. The first step of this work was to create a paper-based electrochemical sensor with a three-electrode system that includes working, counter and reference electrodes. Initially, the cellulose paper is printed on one side with liquid wax, and afterwards, the sheet is placed in a hot plate to melt and diffuse vertically the wax through the porous paper and making it hydrophobic. The next step in the fabrication process of the electrodes is the deposition of the conductive inks (counter and working consisting of carbon and reference consisting of silver). The electrochemical performance of the sensor was assessed by means of cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), square wave voltammetry (SWV) and differential pulse voltammetry (DPV). Different probes were tested and then the electrodes were characterized using [Fe(CN)6]3-/4- redox couple, where a typical voltammogram was obtained with well-defined reduction and oxidation peaks. Several experimental conditions, such as, scan-rate, electrolyte, probe concentration and cleaning procedure have been carefully optimized. As a proof of concept, the electrochemical properties of the carbon-based electrode assembled on paper substrate were tested by growing an electropolymerized layer of a biopolymer consisting on acrylamide. Moreover, in order to demonstrate the applicability of the fabricated sensor, the electrochemical detection of OS biomarker 8-hydroxy-2'- deoxyguanosine (8-OHdG) was tested by DPV. Overall, the main advantage of paper-based electrodes proposed herein are their easy fabrication, without requiring complex or high costly equipment, allowing quick and facile detection of biomolecules.}, keywords = {}, pubstate = {published}, tppubtype = {conference} } In the medicine context, early and accurate diagnosis is a crucial step for successful prevention and efficient therapeutic strategies. Further, the development of new methodologies for detection and quantification of Oxidative Stress (OS) biomarkers in point-of-care constitutes an urgent tool in cancer treatment and survival. Over the last years, paper has become an attractive platform for sensors and biomedical devices due to its portability, low-cost, simplicity and easy to operate modus. Here, our main goal is the assembly of carbon-based electrodes using paper substrate for electrochemical analysis of OS biomarkers. The first step of this work was to create a paper-based electrochemical sensor with a three-electrode system that includes working, counter and reference electrodes. Initially, the cellulose paper is printed on one side with liquid wax, and afterwards, the sheet is placed in a hot plate to melt and diffuse vertically the wax through the porous paper and making it hydrophobic. The next step in the fabrication process of the electrodes is the deposition of the conductive inks (counter and working consisting of carbon and reference consisting of silver). The electrochemical performance of the sensor was assessed by means of cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), square wave voltammetry (SWV) and differential pulse voltammetry (DPV). Different probes were tested and then the electrodes were characterized using [Fe(CN)6]3-/4- redox couple, where a typical voltammogram was obtained with well-defined reduction and oxidation peaks. Several experimental conditions, such as, scan-rate, electrolyte, probe concentration and cleaning procedure have been carefully optimized. As a proof of concept, the electrochemical properties of the carbon-based electrode assembled on paper substrate were tested by growing an electropolymerized layer of a biopolymer consisting on acrylamide. Moreover, in order to demonstrate the applicability of the fabricated sensor, the electrochemical detection of OS biomarker 8-hydroxy-2'- deoxyguanosine (8-OHdG) was tested by DPV. Overall, the main advantage of paper-based electrodes proposed herein are their easy fabrication, without requiring complex or high costly equipment, allowing quick and facile detection of biomolecules. |
MHM Sá, MGF Sales, L Brandão CB modification in order to assemble a MIP-based biosensor powered by DMFCs (Conference) Poster, International Biomedical Engineering Meeting, ESTSP, Biblioteca de Almeida Garrett, Porto, Portugal, 2016. @conference{Sá2016b, title = {CB modification in order to assemble a MIP-based biosensor powered by DMFCs}, author = {MHM Sá and MGF Sales and L Brandão }, year = {2016}, date = {2016-03-21}, address = {Biblioteca de Almeida Garrett, Porto, Portugal}, organization = {Poster, International Biomedical Engineering Meeting, ESTSP,}, abstract = {Direct methanol fuel cells (DMFCs) are extremely attractive as power sources due to the high energy density provided, their easy transport and convenient handling of fuel. One of the main components of DMFCs is the membrane electrode assembly (MEA) which includes a polymer electrolyte and a platinum based catalyst. Carbon blacks (CBs) are most used as Pt supports in the fuel cells due to their low cost and high availability, good electrical performance, and relatively high surface1. The aim of this work is to show how we can modify CB in order to apply this modified material to the assembly an autonomous low cost electrochemical biosensor for a protein biomarker inside a DMFC, taking advantage of the molecular imprinting technology. In this technique molecularly imprinted polymers (MIPs) with tailor-made binding sites complementary to template molecules are used to build biosensors2. The MIPs are able to mimic natural recognition entities, such as antibodies and other biological receptors. In this way they are very useful to analyse complicated samples such as biological fluids3. Our sensory target is a protein biomarker of the rectal colon cancer, the carcinoembryonic antigen (CEA). Cancer along with other diseases may be diagnosed by biomarker detection using conventional tests that have limited application in low-resource settings due to the use of bulky and expensive instrumentation, putting in evidence the advantages of the device we want develop which is low-cost, autonomous and simple of using in the point-of-care. With that aim and taking advantage of the CB support properties we have synthesized by free-radical polymerization a crosslinked vinyl based co-polymer and studied its potential as a MIP material. Morphological observations and detailed experimental characterization by TEM and TG analysis, besides different spectroscopic and electrochemical techniques, revealed that CB surface modifications occurred. Further studies are being undertaken in order to assemble a MIP device based in this material.}, keywords = {}, pubstate = {published}, tppubtype = {conference} } Direct methanol fuel cells (DMFCs) are extremely attractive as power sources due to the high energy density provided, their easy transport and convenient handling of fuel. One of the main components of DMFCs is the membrane electrode assembly (MEA) which includes a polymer electrolyte and a platinum based catalyst. Carbon blacks (CBs) are most used as Pt supports in the fuel cells due to their low cost and high availability, good electrical performance, and relatively high surface1. The aim of this work is to show how we can modify CB in order to apply this modified material to the assembly an autonomous low cost electrochemical biosensor for a protein biomarker inside a DMFC, taking advantage of the molecular imprinting technology. In this technique molecularly imprinted polymers (MIPs) with tailor-made binding sites complementary to template molecules are used to build biosensors2. The MIPs are able to mimic natural recognition entities, such as antibodies and other biological receptors. In this way they are very useful to analyse complicated samples such as biological fluids3. Our sensory target is a protein biomarker of the rectal colon cancer, the carcinoembryonic antigen (CEA). Cancer along with other diseases may be diagnosed by biomarker detection using conventional tests that have limited application in low-resource settings due to the use of bulky and expensive instrumentation, putting in evidence the advantages of the device we want develop which is low-cost, autonomous and simple of using in the point-of-care. With that aim and taking advantage of the CB support properties we have synthesized by free-radical polymerization a crosslinked vinyl based co-polymer and studied its potential as a MIP material. Morphological observations and detailed experimental characterization by TEM and TG analysis, besides different spectroscopic and electrochemical techniques, revealed that CB surface modifications occurred. Further studies are being undertaken in order to assemble a MIP device based in this material. |
LPT Carneiro, MGF Sales, L Brandão Single-walled carbon nanohorns for electrochemical biosensor integration (Conference) Poster, International Biomedical Engineering Meeting, ESTSP, Biblioteca de Almeida Garrett, Porto, Portugal, 2016. @conference{Carneiro2016b, title = {Single-walled carbon nanohorns for electrochemical biosensor integration}, author = {LPT Carneiro and MGF Sales and L Brandão}, year = {2016}, date = {2016-03-21}, address = {Biblioteca de Almeida Garrett, Porto, Portugal}, organization = {Poster, International Biomedical Engineering Meeting, ESTSP,}, abstract = {Carbon based electrochemical sensors are commonly used because of their low cost, good electron transfer kinetics, chemical stability and biocompatibility.[1] This work aims to develop an electrochemical biosensor for targeting cancer biomarkers that will be autonomous by hosting a carbon-based sensing layer inside a fuel cell. Single-walled nanohorns (SWNHs) are used herein as electrocatalyst supports of the fuel cell catalyst that will be used to anchor the biommimetic receptor, assembled by molecular imprinting technology. SWNHs are a class of carbon nanomaterials with a single wall convoluted graphene sheet and a horn shaped tip[2], which are referred in literature as good candidates for usage in fuel cell electrodes.[3] SWNHs were synthesized by using an electric arc discharge in air as described elsewhere.[2] In this work, SWNHs were modified by an oxidation process (in acidic media) and the metal catalyst Platinum (Pt) was deposited onto the surface of the oxidized SWNHs by a chemical reduction method. Additionally, the anchoring of a nonimprinted polymer (control) on SWNHs by a redox free radical polymerization was explored. These results allow establishing the best conditions for the development of the biommimetic receptor. The original and modified SWNHs were characterized by FTIR-ATR, Raman Spectroscopy, TG analysis, TEM and electrochemical studies. The characterization techniques evidenced the occurrence of chemical modifications on the surface of the SWNHs without altering their intrinsic structure. Platinum was successfully anchored on the surface of the modified SWNHs and the electrochemical surface area of the Pt-SWNH was determined by the under potential hydrogen deposition process (HUPD). Evidences of the anchoring of the non-imprinted polymer (NIP) were observed.}, keywords = {}, pubstate = {published}, tppubtype = {conference} } Carbon based electrochemical sensors are commonly used because of their low cost, good electron transfer kinetics, chemical stability and biocompatibility.[1] This work aims to develop an electrochemical biosensor for targeting cancer biomarkers that will be autonomous by hosting a carbon-based sensing layer inside a fuel cell. Single-walled nanohorns (SWNHs) are used herein as electrocatalyst supports of the fuel cell catalyst that will be used to anchor the biommimetic receptor, assembled by molecular imprinting technology. SWNHs are a class of carbon nanomaterials with a single wall convoluted graphene sheet and a horn shaped tip[2], which are referred in literature as good candidates for usage in fuel cell electrodes.[3] SWNHs were synthesized by using an electric arc discharge in air as described elsewhere.[2] In this work, SWNHs were modified by an oxidation process (in acidic media) and the metal catalyst Platinum (Pt) was deposited onto the surface of the oxidized SWNHs by a chemical reduction method. Additionally, the anchoring of a nonimprinted polymer (control) on SWNHs by a redox free radical polymerization was explored. These results allow establishing the best conditions for the development of the biommimetic receptor. The original and modified SWNHs were characterized by FTIR-ATR, Raman Spectroscopy, TG analysis, TEM and electrochemical studies. The characterization techniques evidenced the occurrence of chemical modifications on the surface of the SWNHs without altering their intrinsic structure. Platinum was successfully anchored on the surface of the modified SWNHs and the electrochemical surface area of the Pt-SWNH was determined by the under potential hydrogen deposition process (HUPD). Evidences of the anchoring of the non-imprinted polymer (NIP) were observed. |
M Carneiro, FTC Moreira, R Fernandes, MGF Sales Development of an electrochemical biosensor for miRNA-107 in Alzheimer’s Disease (Conference) Poster, International Biomedical Engineering Meeting, ESTSP, Biblioteca de Almeida Garrett, Porto, Portugal, 2016. @conference{Carneiro2016b, title = {Development of an electrochemical biosensor for miRNA-107 in Alzheimer’s Disease}, author = {M Carneiro and FTC Moreira and R Fernandes and MGF Sales}, year = {2016}, date = {2016-03-21}, address = {Biblioteca de Almeida Garrett, Porto, Portugal}, organization = {Poster, International Biomedical Engineering Meeting, ESTSP,}, abstract = {Alzheimer’s disease is the major cause of dementia worldwide. The ineffectiveness of diagnostic methods in early disease detection and the limitations in therapy approaches, leads to the urgency of finding non-invasive molecular biomarker with high sensitivity and specificity, and the design of new analytical devices that may be used routinely clinical context. In the context of Alzheimer’s disease biomarkers, miRNAs are non-coding RNAs responsible for post-transcriptional genetic regulation. Playing an important role in several biological processes, including the neuronal ones, miRNAs arise today as emerging potential Alzheimer biomarkers. On the other hand, electrochemical biosensors are a promising technology for miRNA detection and quantification, providing fast responses with low cost and simple procedures. This work presents a disposable electrochemical biosensor based on a carbon screen printed electrode (CSPE) for miRNA-107 quantification, with potential application in a point-of-care device for diagnosis of Alzheimer’s disease. C-SPE was assembled applying a commercial carbon ink on a PVC substrate and using this ink to design working, indicating and reference electrodes. The working electrode area was then modified by drop-casting carboxylated multi-walled carbon nanotubes. The carboxylic groups were further activated by carbodiimide action to allow covalent subsequent binding of the amine probe. The carboxylic groups remaining active after binding were deactivated by reaction with L-asparagine. Electrochemical techniques namely cyclic voltammetry (CV) impedance spectroscopy (EIS) and square wave voltammetry (SWV) were used to follow the surface modification of these devices and their ability to hybridize successfully with miRNA-107. Raman Spectroscopy, Fourier Transform Infrared Spectroscopy (FTIR) and Thermogravimetric Analysis (TG) were used for C-SPE surface characterization. All stages of the working electrode modification were confirmed by analysing the cathodic/anodic peak currents and peak-to-peak separation in CV, the semicircle diameter of the Nyquist plot in EIS and the peak current in SWV. Hybridization tests evidence changes in the electrical features of the device and suggests that the here described sensor seems a promising tool miRNA-107 detection in point-of-care, offering simplicity of fabrication, low time response, low cost, good sensitivity and high selectivity.}, keywords = {}, pubstate = {published}, tppubtype = {conference} } Alzheimer’s disease is the major cause of dementia worldwide. The ineffectiveness of diagnostic methods in early disease detection and the limitations in therapy approaches, leads to the urgency of finding non-invasive molecular biomarker with high sensitivity and specificity, and the design of new analytical devices that may be used routinely clinical context. In the context of Alzheimer’s disease biomarkers, miRNAs are non-coding RNAs responsible for post-transcriptional genetic regulation. Playing an important role in several biological processes, including the neuronal ones, miRNAs arise today as emerging potential Alzheimer biomarkers. On the other hand, electrochemical biosensors are a promising technology for miRNA detection and quantification, providing fast responses with low cost and simple procedures. This work presents a disposable electrochemical biosensor based on a carbon screen printed electrode (CSPE) for miRNA-107 quantification, with potential application in a point-of-care device for diagnosis of Alzheimer’s disease. C-SPE was assembled applying a commercial carbon ink on a PVC substrate and using this ink to design working, indicating and reference electrodes. The working electrode area was then modified by drop-casting carboxylated multi-walled carbon nanotubes. The carboxylic groups were further activated by carbodiimide action to allow covalent subsequent binding of the amine probe. The carboxylic groups remaining active after binding were deactivated by reaction with L-asparagine. Electrochemical techniques namely cyclic voltammetry (CV) impedance spectroscopy (EIS) and square wave voltammetry (SWV) were used to follow the surface modification of these devices and their ability to hybridize successfully with miRNA-107. Raman Spectroscopy, Fourier Transform Infrared Spectroscopy (FTIR) and Thermogravimetric Analysis (TG) were used for C-SPE surface characterization. All stages of the working electrode modification were confirmed by analysing the cathodic/anodic peak currents and peak-to-peak separation in CV, the semicircle diameter of the Nyquist plot in EIS and the peak current in SWV. Hybridization tests evidence changes in the electrical features of the device and suggests that the here described sensor seems a promising tool miRNA-107 detection in point-of-care, offering simplicity of fabrication, low time response, low cost, good sensitivity and high selectivity. |
AR Cardoso, HIAS Gomes, APM Tavares, MGF Sales Novel electrochemical sensor for chloramphenicol detection in aquatic medium (Conference) Poster, International Biomedical Engineering Meeting, ESTSP, Biblioteca de Almeida Garrett, Porto, Portugal, 2016. @conference{Cardoso2016b, title = {Novel electrochemical sensor for chloramphenicol detection in aquatic medium}, author = {AR Cardoso and HIAS Gomes and APM Tavares and MGF Sales}, year = {2016}, date = {2016-03-21}, address = {Biblioteca de Almeida Garrett, Porto, Portugal}, organization = {Poster, International Biomedical Engineering Meeting, ESTSP,}, abstract = {The antibiotic resistance represent public health challenges of our time and has recently increased dramatically worldwide. The frequent use of antibiotics and accelerated fast-growing of fish in aquaculture are correlated and represent huge problem for environment and human health, because of health risks, for example increasing of antibiotic resistance in fish pathogens, and transfer this resistance for humans to certain pathogen (bacteria)1,2. Nowadays, exist several countries which the regulations for used the antibiotics are strict and only few antibiotics are licensed for use in aquaculture. In aquaculture have being used several classes of antibiotics: beta-lactams, chloramphenicols, tetracyclines, macrolides, spectinomycin sulphonamides, nitroimidazoles, polymyxins, quinolones and macrocyclics2,3. As consequently the antibiotics are no longer effective in treating bacterial diseases in some cases. For this work was chosen chloramphenicol (CAP). CAP have large spectrum antibiotic and have been wide used in human and animals4. The conventional analytical methods for chloramphenicol residues detection including chromatographic techniques like chromatographic methods using gas chromatography combined with mass spectrometric (GC-MS), liquid chromatograph (LC-MS/MS), chemiluminesence based immunoassays (ELISA)5,6. However, these methods are expensive, as alternative have biosensors, these have met the needs of point-of-care detection, showing several advantageous features compared to conventional methods. These include low cost, portability, good sensitivity/selectivity features, simplicity of use and ability for detection in real time. In this work, a new biosensor is presented for detection chloramphenicol in aquatic medium based in MIP (imprinted polymers). The sensor design was evaluated with electrochemical measurements such as cyclic voltammetry, electrochemical impedance spectroscopy (EIS), and square wave voltammetry (SWV). All these were used to characterize the changes in electron transfer properties against the redox probes (K3[Fe(CN)6]) /(K4[Fe(CN)6]). The chemical changes occurring at the carbon surface along the sensor assembly were followed by Raman spectroscopy. The results shows each modification are done a successful and was visible in all measurements.}, keywords = {}, pubstate = {published}, tppubtype = {conference} } The antibiotic resistance represent public health challenges of our time and has recently increased dramatically worldwide. The frequent use of antibiotics and accelerated fast-growing of fish in aquaculture are correlated and represent huge problem for environment and human health, because of health risks, for example increasing of antibiotic resistance in fish pathogens, and transfer this resistance for humans to certain pathogen (bacteria)1,2. Nowadays, exist several countries which the regulations for used the antibiotics are strict and only few antibiotics are licensed for use in aquaculture. In aquaculture have being used several classes of antibiotics: beta-lactams, chloramphenicols, tetracyclines, macrolides, spectinomycin sulphonamides, nitroimidazoles, polymyxins, quinolones and macrocyclics2,3. As consequently the antibiotics are no longer effective in treating bacterial diseases in some cases. For this work was chosen chloramphenicol (CAP). CAP have large spectrum antibiotic and have been wide used in human and animals4. The conventional analytical methods for chloramphenicol residues detection including chromatographic techniques like chromatographic methods using gas chromatography combined with mass spectrometric (GC-MS), liquid chromatograph (LC-MS/MS), chemiluminesence based immunoassays (ELISA)5,6. However, these methods are expensive, as alternative have biosensors, these have met the needs of point-of-care detection, showing several advantageous features compared to conventional methods. These include low cost, portability, good sensitivity/selectivity features, simplicity of use and ability for detection in real time. In this work, a new biosensor is presented for detection chloramphenicol in aquatic medium based in MIP (imprinted polymers). The sensor design was evaluated with electrochemical measurements such as cyclic voltammetry, electrochemical impedance spectroscopy (EIS), and square wave voltammetry (SWV). All these were used to characterize the changes in electron transfer properties against the redox probes (K3[Fe(CN)6]) /(K4[Fe(CN)6]). The chemical changes occurring at the carbon surface along the sensor assembly were followed by Raman spectroscopy. The results shows each modification are done a successful and was visible in all measurements. |
AM Gomes, APM Tavares, MGF Sales Plastic antibody material for glutamic acid based on molecularly imprinted polymer: Application of potentiometric transduction (Conference) Poster, NanoPT, NanoPorTugal International Conference, INL, Braga, Portugal, 2016. @conference{Gomes2016, title = {Plastic antibody material for glutamic acid based on molecularly imprinted polymer: Application of potentiometric transduction}, author = {AM Gomes and APM Tavares and MGF Sales}, year = {2016}, date = {2016-02-16}, address = {INL, Braga, Portugal}, organization = {Poster, NanoPT, NanoPorTugal International Conference,}, abstract = {Glutamic acid is a nonessential amino acid and a very important neurotransmitter in the central nervous system. From a metabolic point of view, glutamic acid is converted into glutamine by glutamine synthetase. But glutamine is not synthesized in neoplastic cells because glutamine synthetase has a lower activity. Thus, an antagonist of this enzyme interferes with the metabolism of glutamine and can be considered an anti-cancer agent. Glutamic acid is therefore used as a conjugate of anticancer drugs since it causes an increase in drug efficiency while this decrease toxicity. Glutamic acid is also very important in memory retention and has a great utility in lowering blood pressure. In contrast, the increase of the concentration of glutamic acid may be associated with diseases such alzheimer and amyotrophic lateral sclerosis. It is therefore important to develop a biosensor for glutamic acid based on molecularly imprinted polymer and using small, portable and low cost devices that may be employed for routine application in Point-of-care. This work presents for this purpose the use of a molecular imprinting approach in a bulk polymerization format to design a new sensory material for glutamic acid. This was done by combining acrylamide and bis-acrylamide with glutamic acid, having potentiometry as transduction mode. To verify that the obtained potentiometric response was related the target molecule, a non-imprinted material acting as control was prepared in parallel. The presence of glutamic acid in the polymeric matrix was confirmed by performing qualitative studies based in Fourier Transform Spectroscopy (FTIR), Scanning Electron Microscope (SEM) coupled to Spectroscopy X-ray Dispersive Energy (EDS). The developed materials were applied in the preparation of various selective membranes. These membranes were evaluated by recording calibration curves under different pHs and comparing the results. The results in pH 5 showed the best features, associated to a membrane containing an additive, p-tetra-octylphenol, of the sensor material. The electrodes were successfully tested in biological material, urine, displaying a reasonable sensitivity (± 18,32 mV/decade) and a wide range of linear response (1,6x10-6 to 1,48x10-3 moles/L) in a background of blank urine (Figure 1). The selectivity against individual interfering species was also tested. In general, the electrodes displayed food selectivity features. Overall, the results obtained pointed out the possibility of a successful application in real urine samples.}, keywords = {}, pubstate = {published}, tppubtype = {conference} } Glutamic acid is a nonessential amino acid and a very important neurotransmitter in the central nervous system. From a metabolic point of view, glutamic acid is converted into glutamine by glutamine synthetase. But glutamine is not synthesized in neoplastic cells because glutamine synthetase has a lower activity. Thus, an antagonist of this enzyme interferes with the metabolism of glutamine and can be considered an anti-cancer agent. Glutamic acid is therefore used as a conjugate of anticancer drugs since it causes an increase in drug efficiency while this decrease toxicity. Glutamic acid is also very important in memory retention and has a great utility in lowering blood pressure. In contrast, the increase of the concentration of glutamic acid may be associated with diseases such alzheimer and amyotrophic lateral sclerosis. It is therefore important to develop a biosensor for glutamic acid based on molecularly imprinted polymer and using small, portable and low cost devices that may be employed for routine application in Point-of-care. This work presents for this purpose the use of a molecular imprinting approach in a bulk polymerization format to design a new sensory material for glutamic acid. This was done by combining acrylamide and bis-acrylamide with glutamic acid, having potentiometry as transduction mode. To verify that the obtained potentiometric response was related the target molecule, a non-imprinted material acting as control was prepared in parallel. The presence of glutamic acid in the polymeric matrix was confirmed by performing qualitative studies based in Fourier Transform Spectroscopy (FTIR), Scanning Electron Microscope (SEM) coupled to Spectroscopy X-ray Dispersive Energy (EDS). The developed materials were applied in the preparation of various selective membranes. These membranes were evaluated by recording calibration curves under different pHs and comparing the results. The results in pH 5 showed the best features, associated to a membrane containing an additive, p-tetra-octylphenol, of the sensor material. The electrodes were successfully tested in biological material, urine, displaying a reasonable sensitivity (± 18,32 mV/decade) and a wide range of linear response (1,6x10-6 to 1,48x10-3 moles/L) in a background of blank urine (Figure 1). The selectivity against individual interfering species was also tested. In general, the electrodes displayed food selectivity features. Overall, the results obtained pointed out the possibility of a successful application in real urine samples. |
C Hora, L Brandão, MGF Sales Development of an autonomous electrical biosensing device for a colon-rectal cancer protein marker (Conference) Oral Presentation, NanoPT, NanoPorTugal International Conference, INL, Braga, Portugal, 2016. @conference{Hora2016, title = {Development of an autonomous electrical biosensing device for a colon-rectal cancer protein marker}, author = {C Hora and L Brandão and MGF Sales}, year = {2016}, date = {2016-02-16}, address = {INL, Braga, Portugal}, organization = {Oral Presentation, NanoPT, NanoPorTugal International Conference,}, abstract = {Dye-sensitized solar cells (DSSCs) are electrochemical devices capable of transforming photo-energy into electricity. It consists of a porous nanocrystalline semiconductor, titanium dioxide (TiO2), film with dye adsorbed in the surface acting as photoanode, a counter electrode (CE) coated with a catalytic material (platinum) and an iodide/triiodide redox couple-based electrolyte connecting both electrodes that are linked through an external circuit. When the DSSC is illuminated, the sensitizer adsorbs photons and the photoexcited dye injects an electron in the TiO2 conduction band leaving the sensitizer oxidized; the electron travels through the semiconductor, external circuit and reaches the cathode where it reduces the electrolyte. In turn, the redox couple at the electrolyte regenerates the sensitizer, completing the circuit (Figure 1). The DSSC developed herein is to act as an autonomous transducer of an electrochemical biosensor by modifying the counter-electrode with a biorecognition element. Biosensors have two components: a biorecognition element (bioreceptor) and a transducer. When the bioreceptor interacts with the target analyte, this interaction is monitored by the transducer and it changes the energy required to oxidation and that change correlates with the analyte concentration. The TiO2 was deposited in the transparent conductive oxide (TCO) coated glass by doctor blade technique, imprinting a circular area of 0.2 cm2. It was annealed at 450 ºC for 30 min in a furnace and immersed in different dye solutions. The cathode was made by spin-coating a platinum salt, which was after modified by surface imprinting to build a molecularly imprinted polymer (MIP) for carcinoembryonic antigen (CEA) on the CE. A monolayer of the template protein was adsorbed on the Pt/FTO surface and surface imprinting was performed by electro-polymerizing phenol red at 0.8 V vs Ag/AgCl. Different electro-polymerization times were tested to control film thickness in order to prevent overlay the template protein and sterically hinder its removal for creating the negative imprinted sites. Film thicknesses were controlled by the charge passed through the electrode. The template protein was removed from the imprinted sites by potential sweep in acidic medium. Charge transfer resistance increased with CEA concentration between the limits defined by the charge transfer resistance, before and after template removal. After a concentration of 2.5ng/mL, the biosensor started to saturate, possibly indicating that nearly 100 % of the created cavities available for rebinding were occupied (Figure 2). The linear EIS response showed that the biosensor responded from concentrations as low as 0.05 ng/mL, up to 2.5 ng/mL (slope= 0.21). After this concentration, the biosensor started to saturate and the sensitivity decreased by a factor of ~3 (slope= 0.08). The concentration limit for the presence of a colon-rectal cancer is 2.5 ng/mL for non-smokers and 5.0 ng/mL for smokers, indicating that the biosensor showed a good response in the concentration range of interest.}, keywords = {}, pubstate = {published}, tppubtype = {conference} } Dye-sensitized solar cells (DSSCs) are electrochemical devices capable of transforming photo-energy into electricity. It consists of a porous nanocrystalline semiconductor, titanium dioxide (TiO2), film with dye adsorbed in the surface acting as photoanode, a counter electrode (CE) coated with a catalytic material (platinum) and an iodide/triiodide redox couple-based electrolyte connecting both electrodes that are linked through an external circuit. When the DSSC is illuminated, the sensitizer adsorbs photons and the photoexcited dye injects an electron in the TiO2 conduction band leaving the sensitizer oxidized; the electron travels through the semiconductor, external circuit and reaches the cathode where it reduces the electrolyte. In turn, the redox couple at the electrolyte regenerates the sensitizer, completing the circuit (Figure 1). The DSSC developed herein is to act as an autonomous transducer of an electrochemical biosensor by modifying the counter-electrode with a biorecognition element. Biosensors have two components: a biorecognition element (bioreceptor) and a transducer. When the bioreceptor interacts with the target analyte, this interaction is monitored by the transducer and it changes the energy required to oxidation and that change correlates with the analyte concentration. The TiO2 was deposited in the transparent conductive oxide (TCO) coated glass by doctor blade technique, imprinting a circular area of 0.2 cm2. It was annealed at 450 ºC for 30 min in a furnace and immersed in different dye solutions. The cathode was made by spin-coating a platinum salt, which was after modified by surface imprinting to build a molecularly imprinted polymer (MIP) for carcinoembryonic antigen (CEA) on the CE. A monolayer of the template protein was adsorbed on the Pt/FTO surface and surface imprinting was performed by electro-polymerizing phenol red at 0.8 V vs Ag/AgCl. Different electro-polymerization times were tested to control film thickness in order to prevent overlay the template protein and sterically hinder its removal for creating the negative imprinted sites. Film thicknesses were controlled by the charge passed through the electrode. The template protein was removed from the imprinted sites by potential sweep in acidic medium. Charge transfer resistance increased with CEA concentration between the limits defined by the charge transfer resistance, before and after template removal. After a concentration of 2.5ng/mL, the biosensor started to saturate, possibly indicating that nearly 100 % of the created cavities available for rebinding were occupied (Figure 2). The linear EIS response showed that the biosensor responded from concentrations as low as 0.05 ng/mL, up to 2.5 ng/mL (slope= 0.21). After this concentration, the biosensor started to saturate and the sensitivity decreased by a factor of ~3 (slope= 0.08). The concentration limit for the presence of a colon-rectal cancer is 2.5 ng/mL for non-smokers and 5.0 ng/mL for smokers, indicating that the biosensor showed a good response in the concentration range of interest. |
2015
ART Santos, FTC Moreira, MGF Sales A novel antibody-like material for breast cancer antigen CA15-3, used to track breast cancer by potentiometric transduction (Conference) Poster (P12), 6th Graduate Student Symposium on Molecular Imprinting, Medway School of Pharmacy, Kent, United Kingdom, 2015. @conference{Santos2015, title = {A novel antibody-like material for breast cancer antigen CA15-3, used to track breast cancer by potentiometric transduction}, author = {ART Santos and FTC Moreira and MGF Sales}, year = {2015}, date = {2015-08-25}, address = {Medway School of Pharmacy, Kent, United Kingdom}, organization = {Poster (P12), 6th Graduate Student Symposium on Molecular Imprinting,}, abstract = {This work presents the development of a low cost sensor device for the diagnosis of breast cancer in point-of-care, made with new synthetic biomimetic materials inside plasticized poly(vinyl chloride), PVC, membranes, for subsequent potentiometric detection. This concept was applied to target a conventional biomarker in breast cancer: Breast Cancer Antigen (CA15-3). The new biomimetic material was obtained by molecularly-imprinted technology. In this, a plastic antibody was obtained by polymerizing around the biomarker that acted as an obstacle to the growth of the polymeric matrix. The imprinted polymer was specifically synthetized by electropolymerization on an FTO conductive glass, by using cyclic voltammetry, including 40 cycles within -0.2 and 1.0 V. The reaction used for the polymerization included monomer (pyrrol, 5.0×10-3 mol/L) and protein (CA15-3, 100U/mL), all prepared in phosphate buffer saline (PBS), with a pH of 7.2 and 1% of ethylene glycol. The biomarker was removed from the imprinted sites by proteolytic action of proteinase K. The biomimetic material was employed in the construction of potentiometric sensors and tested with regard to its affinity and selectivity for binding CA15-3, by checking the analytical performance of the obtained electrodes. For this purpose, the biomimetic material was dispersed in plasticized PVC membranes, including or not a lipophilic ionic additive, and applied on a solid conductive support of graphite. The analytical behaviour was evaluated in buffer and in synthetic serum, with regard to linear range, limit of detection, repeatability, and reproducibility. This antibody-like material was tested in synthetic serum, and good results were obtained. The best devices were able to detect 5 times less CA15-3 than that required in clinical use. Selectivity assays were also performed, showing that the various serum components did not interfere with this biomarker. Overall, the potentiometric-based methods showed several advantages compared to other methods reported in the literature. The analytical process was simple, providing fast responses for a reduced amount of analyte, with low cost and feasible miniaturization. It also allowed the detection of a wide range of concentrations, diminishing the required efforts in previous sample pre-treating stages.}, keywords = {}, pubstate = {published}, tppubtype = {conference} } This work presents the development of a low cost sensor device for the diagnosis of breast cancer in point-of-care, made with new synthetic biomimetic materials inside plasticized poly(vinyl chloride), PVC, membranes, for subsequent potentiometric detection. This concept was applied to target a conventional biomarker in breast cancer: Breast Cancer Antigen (CA15-3). The new biomimetic material was obtained by molecularly-imprinted technology. In this, a plastic antibody was obtained by polymerizing around the biomarker that acted as an obstacle to the growth of the polymeric matrix. The imprinted polymer was specifically synthetized by electropolymerization on an FTO conductive glass, by using cyclic voltammetry, including 40 cycles within -0.2 and 1.0 V. The reaction used for the polymerization included monomer (pyrrol, 5.0×10-3 mol/L) and protein (CA15-3, 100U/mL), all prepared in phosphate buffer saline (PBS), with a pH of 7.2 and 1% of ethylene glycol. The biomarker was removed from the imprinted sites by proteolytic action of proteinase K. The biomimetic material was employed in the construction of potentiometric sensors and tested with regard to its affinity and selectivity for binding CA15-3, by checking the analytical performance of the obtained electrodes. For this purpose, the biomimetic material was dispersed in plasticized PVC membranes, including or not a lipophilic ionic additive, and applied on a solid conductive support of graphite. The analytical behaviour was evaluated in buffer and in synthetic serum, with regard to linear range, limit of detection, repeatability, and reproducibility. This antibody-like material was tested in synthetic serum, and good results were obtained. The best devices were able to detect 5 times less CA15-3 than that required in clinical use. Selectivity assays were also performed, showing that the various serum components did not interfere with this biomarker. Overall, the potentiometric-based methods showed several advantages compared to other methods reported in the literature. The analytical process was simple, providing fast responses for a reduced amount of analyte, with low cost and feasible miniaturization. It also allowed the detection of a wide range of concentrations, diminishing the required efforts in previous sample pre-treating stages. |
AR Khan, J Riu, S Merino, MGF Sales Molecularly-imprinted polymers for the electrochemical detection of bacterial Flagella (Conference) Poster (P9), 6th Graduate Student Symposium on Molecular Imprinting, Medway School of Pharmacy, Kent, United Kingdom, 2015. @conference{Khan2015, title = {Molecularly-imprinted polymers for the electrochemical detection of bacterial Flagella}, author = {AR Khan and J Riu and S Merino and MGF Sales}, year = {2015}, date = {2015-08-25}, address = {Medway School of Pharmacy, Kent, United Kingdom}, organization = {Poster (P9), 6th Graduate Student Symposium on Molecular Imprinting,}, abstract = {In our daily life, diseases and productivity losses caused by bacteria are very common. It is therefore important to develop suitable strategies for the detection of bacteria. Current methods include culture-based methods with colony counting, polymerase chain reaction, and immunology-based approaches. All these are limited by instability, reusability and cost effective point of view1. From the theoretical point-of-view, the synthesis of artificial receptors such as molecularly-imprinted polymers (MIPs) for bacterial receptors remaining at the outer surface would be a great advance. MIPs, also known as plastic antibodies, have been used extensively in the development of sensors, but so far this type of materials has not been developed in the detection of whole bacteria. Thus, this work proposes the detection of flagella from Proteus mirabilis as a proof of concept. A novel polymeric film of 3-aminophenol where the protein was entrapped in the polymeric matrix is prepared for this purpose, making use of electropolymerization. The protein molecules entrapped in the polymeric backbone were removed by proteinase K proteolytic activity and subsequent electrochemical washing by cyclic voltammetry. The vacant sites so obtained were expected to preserve the shape of the engraved flagella and to rebind target molecules. The imprinted film was synthetized on a receptor surface of single walled carbon nanotubes (SWCNTs), placed at the working area of a screen printed electrode (SPE). The use of a SPE aimed to create a disposable device and enable point-of-care applications. The analytical performance of the obtained devices was followed by electrochemical impedance spectroscopy (EIS), and chemical modifications of the surface were characterized using Fourier Transform Infrared (FTIR) and Raman spectroscopy. Overall, the MIPs/ SWCNTs SPE-based device displayed linear responses to flagella in EIS assay from 0.12 μM to1.12 μM in MES buffer at pH 5.01. In conclusion, optimization and further tests are progressing and point out that the here described sensor seems a promising tool for screening flagella from Proteus mirabilis in point-of-care, due to simplicity of fabrication, reusability, low time response, low cost, good sensitivity and selectivity.}, keywords = {}, pubstate = {published}, tppubtype = {conference} } In our daily life, diseases and productivity losses caused by bacteria are very common. It is therefore important to develop suitable strategies for the detection of bacteria. Current methods include culture-based methods with colony counting, polymerase chain reaction, and immunology-based approaches. All these are limited by instability, reusability and cost effective point of view1. From the theoretical point-of-view, the synthesis of artificial receptors such as molecularly-imprinted polymers (MIPs) for bacterial receptors remaining at the outer surface would be a great advance. MIPs, also known as plastic antibodies, have been used extensively in the development of sensors, but so far this type of materials has not been developed in the detection of whole bacteria. Thus, this work proposes the detection of flagella from Proteus mirabilis as a proof of concept. A novel polymeric film of 3-aminophenol where the protein was entrapped in the polymeric matrix is prepared for this purpose, making use of electropolymerization. The protein molecules entrapped in the polymeric backbone were removed by proteinase K proteolytic activity and subsequent electrochemical washing by cyclic voltammetry. The vacant sites so obtained were expected to preserve the shape of the engraved flagella and to rebind target molecules. The imprinted film was synthetized on a receptor surface of single walled carbon nanotubes (SWCNTs), placed at the working area of a screen printed electrode (SPE). The use of a SPE aimed to create a disposable device and enable point-of-care applications. The analytical performance of the obtained devices was followed by electrochemical impedance spectroscopy (EIS), and chemical modifications of the surface were characterized using Fourier Transform Infrared (FTIR) and Raman spectroscopy. Overall, the MIPs/ SWCNTs SPE-based device displayed linear responses to flagella in EIS assay from 0.12 μM to1.12 μM in MES buffer at pH 5.01. In conclusion, optimization and further tests are progressing and point out that the here described sensor seems a promising tool for screening flagella from Proteus mirabilis in point-of-care, due to simplicity of fabrication, reusability, low time response, low cost, good sensitivity and selectivity. |
GV Martins, E Fortunato, HR Fernandes, MGF Sales A molecularly imprinted sensor for sensitive detection of 8-hydroxy-2'-deoxyguanosine (8-OHdG) oxidative stress biomarker (Conference) Poster (P6), 6th Graduate Student Symposium on Molecular Imprinting, Medway School of Pharmacy, Kent, United Kingdom, 2015. @conference{Martins2015, title = {A molecularly imprinted sensor for sensitive detection of 8-hydroxy-2'-deoxyguanosine (8-OHdG) oxidative stress biomarker}, author = {GV Martins and E Fortunato and HR Fernandes and MGF Sales}, year = {2015}, date = {2015-08-25}, address = {Medway School of Pharmacy, Kent, United Kingdom}, organization = {Poster (P6), 6th Graduate Student Symposium on Molecular Imprinting,}, abstract = {Early diagnosis of Oxidative Stress (OS) biomarkers can be used as a crucial tool in cancer prevention, treatment and survival. In this context, 8-hydroxy-2'-deoxyguanosine (8-OHdG) is a repair product of oxidized guanine lesions and has been acknowledged as a suitable biomarker of OS1. Under this scope, a simple and sensitive molecularly imprinted (MIP)-based sensor for detection of urinary 8-OHdG has been designed via electrochemical polymerization. The biomimetic film was assembled in-situ on the gold-modified electrode through electropolymerization of phenol monomer combined with the target molecule 8-OHdG. The electropolymerization of phenol was performed by Cyclic Voltammetry (CV) over the potential range 0.1 to 0.9 V in PBS buffer at pH 7.4, enabling the formation of a non-conductive layer. Several experimental parameters, such as, the initial concentration of the monomer and the ratio template-monomer, have been carefully optimized and the electrochemical performance of the designed MIP sensor was investigated by CV and Electrochemical Impedance Spectroscopy (EIS). In parallel, RAMAN and FTIR spectroscopies comproved the formation of polyphenol films on the electrode surface by electrochemical oxidation of phenol. Our results demonstrated that 8-OHdG molecule was successfully entrapped into the polymeric matrix, enabling a three-dimensional structure with numerous imprinted cavities sites. The developed electrochemical biosensor showed high sensitivity and selectivity towards 8-OHdG over the concentration range [0.1 - 100] pg/ml. Moreover, it was employed to detect 8-OHdG in urine samples as a non-invasive approach to assess the extent of DNA oxidative damage. Overall, this label-free biosensor constitutes a promising low-cost tool to be implemented as an easy-to-use protocol for sensitive detection of 8-OHdG in biological samples.}, keywords = {}, pubstate = {published}, tppubtype = {conference} } Early diagnosis of Oxidative Stress (OS) biomarkers can be used as a crucial tool in cancer prevention, treatment and survival. In this context, 8-hydroxy-2'-deoxyguanosine (8-OHdG) is a repair product of oxidized guanine lesions and has been acknowledged as a suitable biomarker of OS1. Under this scope, a simple and sensitive molecularly imprinted (MIP)-based sensor for detection of urinary 8-OHdG has been designed via electrochemical polymerization. The biomimetic film was assembled in-situ on the gold-modified electrode through electropolymerization of phenol monomer combined with the target molecule 8-OHdG. The electropolymerization of phenol was performed by Cyclic Voltammetry (CV) over the potential range 0.1 to 0.9 V in PBS buffer at pH 7.4, enabling the formation of a non-conductive layer. Several experimental parameters, such as, the initial concentration of the monomer and the ratio template-monomer, have been carefully optimized and the electrochemical performance of the designed MIP sensor was investigated by CV and Electrochemical Impedance Spectroscopy (EIS). In parallel, RAMAN and FTIR spectroscopies comproved the formation of polyphenol films on the electrode surface by electrochemical oxidation of phenol. Our results demonstrated that 8-OHdG molecule was successfully entrapped into the polymeric matrix, enabling a three-dimensional structure with numerous imprinted cavities sites. The developed electrochemical biosensor showed high sensitivity and selectivity towards 8-OHdG over the concentration range [0.1 - 100] pg/ml. Moreover, it was employed to detect 8-OHdG in urine samples as a non-invasive approach to assess the extent of DNA oxidative damage. Overall, this label-free biosensor constitutes a promising low-cost tool to be implemented as an easy-to-use protocol for sensitive detection of 8-OHdG in biological samples. |
HIAS Gomes, MGF Sales Bulk imprinting based on polytyramine sensor on carbon SPE surface for IL6 detection (Conference) Poster (P3), 6th Graduate Student Symposium on Molecular Imprinting, Medway School of Pharmacy, Kent, United Kingdom, 2015. @conference{Gomes2015b, title = {Bulk imprinting based on polytyramine sensor on carbon SPE surface for IL6 detection}, author = {HIAS Gomes and MGF Sales}, year = {2015}, date = {2015-08-25}, address = {Medway School of Pharmacy, Kent, United Kingdom}, organization = {Poster (P3), 6th Graduate Student Symposium on Molecular Imprinting,}, abstract = {immune response but has also a direct effect on the proliferation and modulation of cellular events in various target tissues.1 IL6 is a 21–28 kDa protein containing 184 amino acids.2 IL6 has many physiologic roles and has been implicated in a number of pathophysiologic processes. A variety of tumour types are stimulated by IL6, including melanoma, renal cell carcinoma, Kaposi’s sarcoma, ovarian carcinoma, lymphoma, and prostate carcinoma.3 There are many methods described in the literature to determine IL6 in fluid and tissue, such as enzyme-linked immunosorbent assay (ELISA)4, fluorescent microarray5, conductometric immunosensing6, chemiluminescence immunoassay7 and fluorescence-based fiber-optic biosensors8. Small, portable and low-cost devices are still necessary, to enable point-of-care analysis in routine context. This work proposes for this purpose a new screen-printed electrode (SPE) device that was sensitized to IL6 by assembling an antiboby-like material on its working area. This was done by bulk imprinting combined with electropolymerization. In this, the target protein (IL6) and the monomer (tyramine) were mixed together in PBS buffer aqueous solution, and a drop of this solution was place on the SPE. A suitable electrical stimulus was then applied on the electrode surface, leading to the formation of a polymeric layer on the surface of this electrode, with a high level of growth control. The template was after removed by a combination of electrical/chemical approach. Studies regarding this material are progressing and results pointed out that this novel device will turn out an alternative approach to current techniques described in the literature.}, keywords = {}, pubstate = {published}, tppubtype = {conference} } immune response but has also a direct effect on the proliferation and modulation of cellular events in various target tissues.1 IL6 is a 21–28 kDa protein containing 184 amino acids.2 IL6 has many physiologic roles and has been implicated in a number of pathophysiologic processes. A variety of tumour types are stimulated by IL6, including melanoma, renal cell carcinoma, Kaposi’s sarcoma, ovarian carcinoma, lymphoma, and prostate carcinoma.3 There are many methods described in the literature to determine IL6 in fluid and tissue, such as enzyme-linked immunosorbent assay (ELISA)4, fluorescent microarray5, conductometric immunosensing6, chemiluminescence immunoassay7 and fluorescence-based fiber-optic biosensors8. Small, portable and low-cost devices are still necessary, to enable point-of-care analysis in routine context. This work proposes for this purpose a new screen-printed electrode (SPE) device that was sensitized to IL6 by assembling an antiboby-like material on its working area. This was done by bulk imprinting combined with electropolymerization. In this, the target protein (IL6) and the monomer (tyramine) were mixed together in PBS buffer aqueous solution, and a drop of this solution was place on the SPE. A suitable electrical stimulus was then applied on the electrode surface, leading to the formation of a polymeric layer on the surface of this electrode, with a high level of growth control. The template was after removed by a combination of electrical/chemical approach. Studies regarding this material are progressing and results pointed out that this novel device will turn out an alternative approach to current techniques described in the literature. |
LAANA Truta, MGF Sales The potential of molecular imprinting as a biosensing devices for monitoring the CEA cancer biomarker (Conference) Poster (P5), 6th Graduate Student Symposium on Molecular Imprinting, Medway School of Pharmacy, Kent, United Kingdom, 2015. @conference{Truta2015b, title = {The potential of molecular imprinting as a biosensing devices for monitoring the CEA cancer biomarker}, author = {LAANA Truta and MGF Sales}, year = {2015}, date = {2015-08-25}, address = {Medway School of Pharmacy, Kent, United Kingdom}, organization = {Poster (P5), 6th Graduate Student Symposium on Molecular Imprinting,}, abstract = {Colorectal cancer is the third most common type of cancer and the major cause of the death throughout the world. Widely known, carcinoembryonic antigen (CEA) is an important tumour marker responsible for clinical diagnosis of 95% of all colon tumors1. The discovery of novel non-invasive biomarkers, as CEA, and its fast determination at low cost is presently required, to enable its use over wide screening programs and applications in point-of-care context, and, thus, its monitoring quite early. As a novel approach, this work proposes a novel support with molecular imprinted polymer (MIP) for CEA cancer biomarker based on carbon ink matrix linked by sol-gel chemistry on top of conductive glass covered by fluorine-doped tin oxide (FTO glass). In brief, the electrical biosensor was tailored on top of a disposable conductive glass electrode, following a bottom-up approach. The several stages of this process included the chemical modification of a homemade carbon ink layer and the assembly of a MIP or non-imprinted polymer (NIP) layer. The analytical performance of the obtained devices was followed by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). Chemical modifications of the surface were characterized using Fourier Transform Infrared (FTIR), and Raman spectroscopy with confocal microscopy. Overall, the MIP/FTO glass-based device displayed linear responses to CEA in EIS assays from 2.5×10-3 μg.mL-1 to 1.25 μg.mL-1 in PBS buffer, with detection limits of 2.5×10-3 μg.mL-1. Successful detection of CEA was, also, achieved in spiked samples of fetal bovine serum. In conclusion, the devices developed are a promising tool for the monitoring of CEA in a point-of-care applications, due to its detection capability below the normal physiological levels expected for this cancer biomarker, simplicity of manufacture, low-cost and good sensitivity and selectivity.}, keywords = {}, pubstate = {published}, tppubtype = {conference} } Colorectal cancer is the third most common type of cancer and the major cause of the death throughout the world. Widely known, carcinoembryonic antigen (CEA) is an important tumour marker responsible for clinical diagnosis of 95% of all colon tumors1. The discovery of novel non-invasive biomarkers, as CEA, and its fast determination at low cost is presently required, to enable its use over wide screening programs and applications in point-of-care context, and, thus, its monitoring quite early. As a novel approach, this work proposes a novel support with molecular imprinted polymer (MIP) for CEA cancer biomarker based on carbon ink matrix linked by sol-gel chemistry on top of conductive glass covered by fluorine-doped tin oxide (FTO glass). In brief, the electrical biosensor was tailored on top of a disposable conductive glass electrode, following a bottom-up approach. The several stages of this process included the chemical modification of a homemade carbon ink layer and the assembly of a MIP or non-imprinted polymer (NIP) layer. The analytical performance of the obtained devices was followed by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). Chemical modifications of the surface were characterized using Fourier Transform Infrared (FTIR), and Raman spectroscopy with confocal microscopy. Overall, the MIP/FTO glass-based device displayed linear responses to CEA in EIS assays from 2.5×10-3 μg.mL-1 to 1.25 μg.mL-1 in PBS buffer, with detection limits of 2.5×10-3 μg.mL-1. Successful detection of CEA was, also, achieved in spiked samples of fetal bovine serum. In conclusion, the devices developed are a promising tool for the monitoring of CEA in a point-of-care applications, due to its detection capability below the normal physiological levels expected for this cancer biomarker, simplicity of manufacture, low-cost and good sensitivity and selectivity. |
NS Ferreira, APM Tavares, MGF Sales New modified electrochemical conductive paper support for BSA detection (Conference) Poster (P8), 6th Graduate Student Symposium on Molecular Imprinting, Medway School of Pharmacy, Kent, United Kingdom, 2015. (BibTeX) @conference{Ferreira2015, title = {New modified electrochemical conductive paper support for BSA detection}, author = {NS Ferreira and APM Tavares and MGF Sales}, year = {2015}, date = {2015-08-25}, address = {Medway School of Pharmacy, Kent, United Kingdom}, organization = {Poster (P8), 6th Graduate Student Symposium on Molecular Imprinting,}, keywords = {}, pubstate = {published}, tppubtype = {conference} } |
JRL Guerreiro, VE Bochenkov, K Runager, H Aslan, M Dong, VAP Freitas, MGF Sales, DS Sutherland Molecular imprinting of complex matrices at localized surface plasmon resonance for screening global interactions polyphenols-proteins (Conference) Oral Presentation (O17), 6th Graduate Student Symposium on Molecular Imprinting, Medway School of Pharmacy, Kent, United Kingdom, 2015. @conference{Guerreiro2015, title = {Molecular imprinting of complex matrices at localized surface plasmon resonance for screening global interactions polyphenols-proteins}, author = {JRL Guerreiro and VE Bochenkov and K Runager and H Aslan and M Dong and VAP Freitas and MGF Sales and DS Sutherland}, year = {2015}, date = {2015-08-25}, address = {Medway School of Pharmacy, Kent, United Kingdom}, organization = {Oral Presentation (O17), 6th Graduate Student Symposium on Molecular Imprinting,}, abstract = {Polyphenols have been highlighted as natural preventing agents of a broad range of diseases such as Alzheimer’s, Parkinson’s, coronary heart diseases, as well as provide anticarcinogenic and anti-inflammatory activities1-4. This protective effect seem to be associated with polyphenols radical scavenging activity but also with their capability to bind proteins, exerting a modulator action in receptor-ligand interactions.5 Upon ingestion, polyphenols might reach different sites of action and bind to complex protein environment giving a complex set of global interactions likely determining their effect. Considering that biological environments are often complex and not completely well define in terms of composition, an effective tools to study and characterize the specific and global interactions between small molecules, such as polyphenols and complex protein matrices could be an advantage. Here we present a combination of a novel molecular imprinting approach and plasmonic nanodisk refractive index sensors to demonstrate a reusable device for studying interactions of small molecules (e.g. dietary polyphenols) with a complex protein matrix.}, keywords = {}, pubstate = {published}, tppubtype = {conference} } Polyphenols have been highlighted as natural preventing agents of a broad range of diseases such as Alzheimer’s, Parkinson’s, coronary heart diseases, as well as provide anticarcinogenic and anti-inflammatory activities1-4. This protective effect seem to be associated with polyphenols radical scavenging activity but also with their capability to bind proteins, exerting a modulator action in receptor-ligand interactions.5 Upon ingestion, polyphenols might reach different sites of action and bind to complex protein environment giving a complex set of global interactions likely determining their effect. Considering that biological environments are often complex and not completely well define in terms of composition, an effective tools to study and characterize the specific and global interactions between small molecules, such as polyphenols and complex protein matrices could be an advantage. Here we present a combination of a novel molecular imprinting approach and plasmonic nanodisk refractive index sensors to demonstrate a reusable device for studying interactions of small molecules (e.g. dietary polyphenols) with a complex protein matrix. |
R Gomes, FTC Moreira, R Fernandes, MGF Sales O-phenylenediamine-based biomimetic sensor for breast tumour antigen detection (Conference) Oral Presentation (O6), 6th Graduate Student Symposium on Molecular Imprinting, Medway School of Pharmacy, Kent, United Kingdom, 2015. @conference{Gomes2015b, title = {O-phenylenediamine-based biomimetic sensor for breast tumour antigen detection}, author = {R Gomes and FTC Moreira and R Fernandes and MGF Sales}, year = {2015}, date = {2015-08-25}, address = {Medway School of Pharmacy, Kent, United Kingdom}, organization = {Oral Presentation (O6), 6th Graduate Student Symposium on Molecular Imprinting,}, abstract = {Intoduction With current advances in cancer treatment, new approaches are required at the early stage diagnostic of cancer. Non-expensive, non-invasive and point-of-care testing is needed to increase access to early cancer screening to a wide range of the population. Herein, an alternative device is proposed, including a biomimetic film synthesized over a conductive glass and acting as synthetic receptor for Breast Tumour Antigen, the first protein acting as cancer biomarker in breast cancer disease. Material and Methods Electrochemical measurements were conducted with a potentiostat/galvanostat from Metrohm Autolab and a PGSTAT302N, equipped with a FRA module and controlled by Nova software. The biomimetic film was obtained by electro-polymerizing ophenylenediamine around the Breast Tumour Antigen target protein that was adsorbed on a FTO cover glass support and incubated within charged monomers. After the polymerization, the vacant sites were obtained by enzymatically removing the protein structures. The ability of the biomaterial to rebind the protein biomarker was measured by electrochemical techniques, namely impedance spectroscopy (EIS) and square wave voltammetry (SWV). Results and Discussion The FTO/Glass/oPDA devices displayed linear responses to Breast Tumour Antigen both in EIS and SWV assays, down to 0.05 U/mL and 5.0 U/mL, respectively, with detection limits of 10.0 and 0.005 U/mL. Further tests are progressing and point out that the here described sensor seems a promising tool for screening Breast Tumour Antigen in point-of-care, due the simplicity of fabrication, reusability, low time response, low cost, good sensitivity and selectivity.}, keywords = {}, pubstate = {published}, tppubtype = {conference} } Intoduction With current advances in cancer treatment, new approaches are required at the early stage diagnostic of cancer. Non-expensive, non-invasive and point-of-care testing is needed to increase access to early cancer screening to a wide range of the population. Herein, an alternative device is proposed, including a biomimetic film synthesized over a conductive glass and acting as synthetic receptor for Breast Tumour Antigen, the first protein acting as cancer biomarker in breast cancer disease. Material and Methods Electrochemical measurements were conducted with a potentiostat/galvanostat from Metrohm Autolab and a PGSTAT302N, equipped with a FRA module and controlled by Nova software. The biomimetic film was obtained by electro-polymerizing ophenylenediamine around the Breast Tumour Antigen target protein that was adsorbed on a FTO cover glass support and incubated within charged monomers. After the polymerization, the vacant sites were obtained by enzymatically removing the protein structures. The ability of the biomaterial to rebind the protein biomarker was measured by electrochemical techniques, namely impedance spectroscopy (EIS) and square wave voltammetry (SWV). Results and Discussion The FTO/Glass/oPDA devices displayed linear responses to Breast Tumour Antigen both in EIS and SWV assays, down to 0.05 U/mL and 5.0 U/mL, respectively, with detection limits of 10.0 and 0.005 U/mL. Further tests are progressing and point out that the here described sensor seems a promising tool for screening Breast Tumour Antigen in point-of-care, due the simplicity of fabrication, reusability, low time response, low cost, good sensitivity and selectivity. |
MGF Sales Uma nova estratégia rumo à deteção de biomarcadores do cancro (Conference) Oradora Convidada, Conferências em Oncobiologia, Faculdade de Farmácia da Universidade do Porto, Portugal, 2015. (BibTeX) @conference{Sales2015, title = {Uma nova estratégia rumo à deteção de biomarcadores do cancro}, author = {MGF Sales}, year = {2015}, date = {2015-05-26}, address = {Faculdade de Farmácia da Universidade do Porto, Portugal}, institution = {Faculdade de Farmácia da Universidade do Porto}, organization = {Oradora Convidada, Conferências em Oncobiologia,}, howpublished = {Oradora convidada, apresentada em conferências em Oncobiologia, Faculdade de Farmácia da Universidade do Porto, Portugal}, keywords = {}, pubstate = {published}, tppubtype = {conference} } |
APM Tavares, MGF Sales Synthesis of an antibody-like material for the detection of Albumin (Conference) Poster (P2), 6th Graduate Student Symposium on Molecular Imprinting, Medway School of Pharmacy, Kent, United Kingdom, 2015. (BibTeX) @conference{Tavares2015, title = {Synthesis of an antibody-like material for the detection of Albumin}, author = {APM Tavares and MGF Sales}, year = {2015}, date = {2015-05-25}, address = {Medway School of Pharmacy, Kent, United Kingdom}, organization = {Poster (P2), 6th Graduate Student Symposium on Molecular Imprinting,}, keywords = {}, pubstate = {published}, tppubtype = {conference} } |
MGF Sales Anticorpos plásticos e células fotovoltaicas na deteção de biomarcadores do cancro (Conference) Palestra convidada, VIII Encontro Nacional de Estudantes de Bioquímica Ciências da Universidade do Algarve, Portugal, 2015. (BibTeX) @conference{Sales2015b, title = {Anticorpos plásticos e células fotovoltaicas na deteção de biomarcadores do cancro}, author = {MGF Sales}, year = {2015}, date = {2015-03-27}, address = {Ciências da Universidade do Algarve, Portugal}, organization = {Palestra convidada, VIII Encontro Nacional de Estudantes de Bioquímica}, keywords = {}, pubstate = {published}, tppubtype = {conference} } |
2014
AR Cardoso, R Fernandes, FTC Moreira, MGF Sales Development of a biosensor for miRNA in Breast Cancer (Conference) Poster (J9), First ASPIC International Conference, the Portuguese Association of Cancer Research, Fundação Calouste Gulbenkian, Lisboa, Portugal, 2014. @conference{Cardoso2014, title = {Development of a biosensor for miRNA in Breast Cancer}, author = {AR Cardoso and R Fernandes and FTC Moreira and MGF Sales}, year = {2014}, date = {2014-11-25}, address = {Fundação Calouste Gulbenkian, Lisboa, Portugal}, organization = {Poster (J9), First ASPIC International Conference, the Portuguese Association of Cancer Research,}, abstract = {Introduction MicroRNA (miRNA) has emerged as a possible new kind of biomarkers of early diagnosis in cancer. It plays an essential role in biological processes such as development, cell proliferation, apoptosis, stress response, and tumorigenesis. Finding new and simple methods the carry out this determination in biological fluids and in point-of-care is therefore an emerging issue. Biosensors are currently an alternative to conventional techniques in clinical analysis, providing fast results, being portable and allowing direct sample reading. In brief, these devices convert the interaction of a biorecognition element with a target analyte into a measurable signal. In the present study, the biorecognition element is a complementary single-stranded oligonucleotide of the target miRNA. Electrical signals are an outcome of the hybridization event between target and complementary strands, thereby acting as an electrochemical biosensor. The combined use of electrochemical biosensors for detecting MiR-155 is presented herein, applied in breast cancer. This miRNA is markedly overexpressed in breast cancer tissues and is one of the most potent miRNA suppressors of apoptosis in breast cancer cells. To our knowledge, there are no other works in this context reported in the literature. Materials and Methods The electrochemical biosensor is a commercial screen-printed electrode (SPE), in which the working area is made of gold. The biorecognition element is a thiol-terminated single-stranded oligonucleotide that is complementary to the targeted species. Its immobilization is granted by covalent attachment of the –SH group of the oligonucleotide on the receptor surface. The modification of the gold-surface is followed by Raman Spectroscopy and FTIR techniques. The electrical signals generated are checked several electrochemical approaches, including cyclic voltammetry, square-wave voltammetry, and electrochemical impedance spectroscopy Results The hybridization event hinders the electrical flow generated by a standard probe of Fe(II)/Fe(III) standing on the sensing area, which generates an impedance change. The co- immobilization of linear and short carbon chain species with different functional groups is tested for improving the correct orientation of the oligonucleotides on the surface and non-specific binding. The electrical response of the biosensor is calibrated against standard miRNA solutions, for subsequent application in spiked serum samples. Acknowledgement: The authors acknowledge the financial support of the European Research Council, through Starting Grant 3P’s/ERC (GA 311086).}, keywords = {}, pubstate = {published}, tppubtype = {conference} } Introduction MicroRNA (miRNA) has emerged as a possible new kind of biomarkers of early diagnosis in cancer. It plays an essential role in biological processes such as development, cell proliferation, apoptosis, stress response, and tumorigenesis. Finding new and simple methods the carry out this determination in biological fluids and in point-of-care is therefore an emerging issue. Biosensors are currently an alternative to conventional techniques in clinical analysis, providing fast results, being portable and allowing direct sample reading. In brief, these devices convert the interaction of a biorecognition element with a target analyte into a measurable signal. In the present study, the biorecognition element is a complementary single-stranded oligonucleotide of the target miRNA. Electrical signals are an outcome of the hybridization event between target and complementary strands, thereby acting as an electrochemical biosensor. The combined use of electrochemical biosensors for detecting MiR-155 is presented herein, applied in breast cancer. This miRNA is markedly overexpressed in breast cancer tissues and is one of the most potent miRNA suppressors of apoptosis in breast cancer cells. To our knowledge, there are no other works in this context reported in the literature. Materials and Methods The electrochemical biosensor is a commercial screen-printed electrode (SPE), in which the working area is made of gold. The biorecognition element is a thiol-terminated single-stranded oligonucleotide that is complementary to the targeted species. Its immobilization is granted by covalent attachment of the –SH group of the oligonucleotide on the receptor surface. The modification of the gold-surface is followed by Raman Spectroscopy and FTIR techniques. The electrical signals generated are checked several electrochemical approaches, including cyclic voltammetry, square-wave voltammetry, and electrochemical impedance spectroscopy Results The hybridization event hinders the electrical flow generated by a standard probe of Fe(II)/Fe(III) standing on the sensing area, which generates an impedance change. The co- immobilization of linear and short carbon chain species with different functional groups is tested for improving the correct orientation of the oligonucleotides on the surface and non-specific binding. The electrical response of the biosensor is calibrated against standard miRNA solutions, for subsequent application in spiked serum samples. Acknowledgement: The authors acknowledge the financial support of the European Research Council, through Starting Grant 3P’s/ERC (GA 311086). |
APM Tavares, NS Ferreira, LAANA Truta, MGF Sales A new biomimetic sensor for detecting carnitine, a potential biomarker in ovarian cancer (Conference) Poster (J9), First ASPIC International Conference, the Portuguese Association of Cancer Research, Fundação Calouste Gulbenkian, Lisboa, Portugal, 2014. @conference{Tavares2014, title = {A new biomimetic sensor for detecting carnitine, a potential biomarker in ovarian cancer}, author = {APM Tavares and NS Ferreira and LAANA Truta and MGF Sales}, year = {2014}, date = {2014-11-25}, address = {Fundação Calouste Gulbenkian, Lisboa, Portugal}, organization = {Poster (J9), First ASPIC International Conference, the Portuguese Association of Cancer Research,}, abstract = {Introduction Carnitine (CRT) displays an important role in cellular metabolism and energy production. It has actions that include the metabolites associated with glycolysis and β-oxidation of fatty acids. The change of its levels in biological fluids has been associated to the presence of ovarian cancer, making CRT a potential biomarker of the disease. Sensitive CRT determination (in low levels) becomes therefore important, for which a low cost and sensitive device would be appreciated. A biomimetic polymer is proposed herein for this purpose, produced by bulk electropolymerization around a hydrophobic paper substrate that was made conductive by casting a graphite-based ink. Materials and methods The electrode substrate was prepared by modifying cellulose paper, first with solid wax and after with carbon ink. The hydrophobicity of the paper was tested by contact angle and the ink properties evaluated by Thermogravimetry, Raman Spectroscopy and FTIR. Two different biomimetic materials were electropolymerized over the carbon conductive support: 3,4-ethylenedioxythiophene (EDOT) and dodecilbenzenesulfonic acid sodium salt (NaDBS). The polymeric film depositions were obtained by chronoamperometry at 0.9 V vs Ag/AgCl during 240 s. The obtained sensors were characterized by Electrochemical Impedance Spectroscopy (EIS), in 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES) buffer at pH 7.0. Results The EDOT and NaDBS-based biomimetic sensors were calibrated by EIS using CRT standard solutions. The results showed linear responses over a wide concentration range, with average slopes of 303 and 450 Ω×L/mol, and detection limits of 1x10-9 and 1x10-8 mol/L, respectively. Both sensors exhibited good selectivity for CRT in diluted urine samples. Their application to the analysis of spiked urine samples revealed relative errors < 16% and the possibility of reusing the sensor after each calibration. In addition, the conductive ink proved good thermal stability and reusability. Overall, the biomimetic sensors described herein seem a successful approach for the determination of CRT in urine. Acknowledgement: The authors acknowledge the financial support of the European Research Council, through Starting Grant 3P’s/ERC (GA 311086).}, keywords = {}, pubstate = {published}, tppubtype = {conference} } Introduction Carnitine (CRT) displays an important role in cellular metabolism and energy production. It has actions that include the metabolites associated with glycolysis and β-oxidation of fatty acids. The change of its levels in biological fluids has been associated to the presence of ovarian cancer, making CRT a potential biomarker of the disease. Sensitive CRT determination (in low levels) becomes therefore important, for which a low cost and sensitive device would be appreciated. A biomimetic polymer is proposed herein for this purpose, produced by bulk electropolymerization around a hydrophobic paper substrate that was made conductive by casting a graphite-based ink. Materials and methods The electrode substrate was prepared by modifying cellulose paper, first with solid wax and after with carbon ink. The hydrophobicity of the paper was tested by contact angle and the ink properties evaluated by Thermogravimetry, Raman Spectroscopy and FTIR. Two different biomimetic materials were electropolymerized over the carbon conductive support: 3,4-ethylenedioxythiophene (EDOT) and dodecilbenzenesulfonic acid sodium salt (NaDBS). The polymeric film depositions were obtained by chronoamperometry at 0.9 V vs Ag/AgCl during 240 s. The obtained sensors were characterized by Electrochemical Impedance Spectroscopy (EIS), in 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES) buffer at pH 7.0. Results The EDOT and NaDBS-based biomimetic sensors were calibrated by EIS using CRT standard solutions. The results showed linear responses over a wide concentration range, with average slopes of 303 and 450 Ω×L/mol, and detection limits of 1x10-9 and 1x10-8 mol/L, respectively. Both sensors exhibited good selectivity for CRT in diluted urine samples. Their application to the analysis of spiked urine samples revealed relative errors < 16% and the possibility of reusing the sensor after each calibration. In addition, the conductive ink proved good thermal stability and reusability. Overall, the biomimetic sensors described herein seem a successful approach for the determination of CRT in urine. Acknowledgement: The authors acknowledge the financial support of the European Research Council, through Starting Grant 3P’s/ERC (GA 311086). |
GV Martins, E Fortunato, HR Fernandes, MGF Sales A biomimetic sensor for monitoring oxidative stress biomarker in point-of-care (Conference) Poster (J5), First ASPIC International Conference, the Portuguese Association of Cancer Research, Fundação Calouste Gulbenkian, Lisboa, Portugal, 2014. @conference{Martins2014, title = {A biomimetic sensor for monitoring oxidative stress biomarker in point-of-care}, author = {GV Martins and E Fortunato and HR Fernandes and MGF Sales}, year = {2014}, date = {2014-11-25}, address = {Fundação Calouste Gulbenkian, Lisboa, Portugal}, organization = {Poster (J5), First ASPIC International Conference, the Portuguese Association of Cancer Research,}, abstract = {damage to biomolecules, a process that seems to play an important role at the origin of cancer. 8- Hydroxy-2'-deoxyguanosine (8-OHdG) is a major product of DNA hydroxylation and is considered a biomarker of damage caused by oxidative stress (OS). Thus, early diagnosis of OS biomarkers may be used as a fundamental tool in cancer prevention and in more efficient therapeutic strategies. For this purpose, a biomimetic sensor for 8-OHdG detection and quantification by Electrochemical Impedance Spectroscopy (EIS) is proposed herein. The biomimetic sensor was obtained by modifying a clean gold (Au) electrode with a OH-terminal thiol compound, followed by direct electropolymerization of phenol in the presence of 8-OHdG. The biomimetic/Au acted as working electrode, while glassy carbon and Ag/AgCl were used as counter and reference electrodes, respectively. Electropolymerization of phenol was performed by Cyclic Voltammetry (CV) over the potential range 0.2 to 0.9 V in pH 7.0 PBS buffer, enabling the formation of a non-conductive layer. Non-imprinted materials (NIM) were also performed by removing the template from the procedure and, then, the ability of the polymer to interact non-specifically with the template was measured. Preliminary results showed the development of a direct and label-free biomimetic sensor with good performance, stability and sensibility. In particular, only MIP material was able to rebind to the target molecule and produce a linear response against EIS on the range 0.010 to 10ng/ml. Overall, the biosensor described herein is simple, precise and may allow routine use for biological samples on-site.}, keywords = {}, pubstate = {published}, tppubtype = {conference} } damage to biomolecules, a process that seems to play an important role at the origin of cancer. 8- Hydroxy-2'-deoxyguanosine (8-OHdG) is a major product of DNA hydroxylation and is considered a biomarker of damage caused by oxidative stress (OS). Thus, early diagnosis of OS biomarkers may be used as a fundamental tool in cancer prevention and in more efficient therapeutic strategies. For this purpose, a biomimetic sensor for 8-OHdG detection and quantification by Electrochemical Impedance Spectroscopy (EIS) is proposed herein. The biomimetic sensor was obtained by modifying a clean gold (Au) electrode with a OH-terminal thiol compound, followed by direct electropolymerization of phenol in the presence of 8-OHdG. The biomimetic/Au acted as working electrode, while glassy carbon and Ag/AgCl were used as counter and reference electrodes, respectively. Electropolymerization of phenol was performed by Cyclic Voltammetry (CV) over the potential range 0.2 to 0.9 V in pH 7.0 PBS buffer, enabling the formation of a non-conductive layer. Non-imprinted materials (NIM) were also performed by removing the template from the procedure and, then, the ability of the polymer to interact non-specifically with the template was measured. Preliminary results showed the development of a direct and label-free biomimetic sensor with good performance, stability and sensibility. In particular, only MIP material was able to rebind to the target molecule and produce a linear response against EIS on the range 0.010 to 10ng/ml. Overall, the biosensor described herein is simple, precise and may allow routine use for biological samples on-site. |
R Gomes, R Fernandes, FTC Moreira, MGF Sales Biomimetic sensor for breast cancer antigen (Conference) Poster (J4), First ASPIC International Conference, the Portuguese Association of Cancer Research, Fundação Calouste Gulbenkian, Lisboa, Portugal, 2014. @conference{Gomes2014, title = {Biomimetic sensor for breast cancer antigen}, author = {R Gomes and R Fernandes and FTC Moreira and MGF Sales}, year = {2014}, date = {2014-11-25}, address = {Fundação Calouste Gulbenkian, Lisboa, Portugal}, organization = {Poster (J4), First ASPIC International Conference, the Portuguese Association of Cancer Research,}, abstract = {Intoduction Monitoring protein biomarkers in circulating fluids is currently an important approach towards non-invasive procedures in cancer screening. Clinical application of biomarker screening has been unfeasible until now in a wide range of the population or in point-of-care testing (where speed of response is a prime consideration). It requires highly sophisticated equipment and/or relies on the use of biological unstable material. Herein, an alternative device is proposed, including a biomimetic film as synthetic receptor for Breast Tumour Antigen, the first protein acting as cancer biomarker in breast cancer disease. Material and Methods The electrochemical measurements were conducted with a potentiostat/galvanostat from Metrohm Autolab and a PGSTAT302N, equipped with a FRA module and controlled by Nova software. Raman measurements were performed using a Thermo Scientific DXR Raman microscope system with a 100 mW 532 nm excitation laser. The biomimetic film was obtained by electro-polymerizing o-phenylenediamine around the Breast Tumour Antigen target that was adsorbed on a gold (Au) support and incubated in charged monomers. The gold (Au) working area was included in a screen printed electrode (SPE), in order to allow the production of disposable devices and enable point-of-care application. After terminating the polymerization, the protein structures that remained in the outer surface were enzymatically removed, leaving behind vacant sites to which the same kind of protein could favourably rebind. RAMAN analyses were performed to follow the surface modification of the Au-SPE. The ability of the biomaterial to rebind the protein biomarker was measured by electrochemical techniques, namely impedance spectroscopy (EIS) and square wave voltammetry (SWV). Results and Discussion The Au-SPE/oPDA devices displayed linear responses to Breast Tumour Antigen both in EIS and SWV assays, down to 0.5 U/mL and 10.0 U/mL, respectively, with detection limits of 40.0 and 0.005 U/mL. Further tests are progressing and point out that the here described sensor seems a promising tool for screening Breast Tumour Antigen in point-of-care, due the simplicity of fabrication, reusability, low time response, low cost, good sensitivity and selectivity. Acknowledgements The authors acknowledge the financial support of European Research Council though the Starting Grant, ERC-StG-3P’s/2012, GA 311086 (to MGF Sales).}, keywords = {}, pubstate = {published}, tppubtype = {conference} } Intoduction Monitoring protein biomarkers in circulating fluids is currently an important approach towards non-invasive procedures in cancer screening. Clinical application of biomarker screening has been unfeasible until now in a wide range of the population or in point-of-care testing (where speed of response is a prime consideration). It requires highly sophisticated equipment and/or relies on the use of biological unstable material. Herein, an alternative device is proposed, including a biomimetic film as synthetic receptor for Breast Tumour Antigen, the first protein acting as cancer biomarker in breast cancer disease. Material and Methods The electrochemical measurements were conducted with a potentiostat/galvanostat from Metrohm Autolab and a PGSTAT302N, equipped with a FRA module and controlled by Nova software. Raman measurements were performed using a Thermo Scientific DXR Raman microscope system with a 100 mW 532 nm excitation laser. The biomimetic film was obtained by electro-polymerizing o-phenylenediamine around the Breast Tumour Antigen target that was adsorbed on a gold (Au) support and incubated in charged monomers. The gold (Au) working area was included in a screen printed electrode (SPE), in order to allow the production of disposable devices and enable point-of-care application. After terminating the polymerization, the protein structures that remained in the outer surface were enzymatically removed, leaving behind vacant sites to which the same kind of protein could favourably rebind. RAMAN analyses were performed to follow the surface modification of the Au-SPE. The ability of the biomaterial to rebind the protein biomarker was measured by electrochemical techniques, namely impedance spectroscopy (EIS) and square wave voltammetry (SWV). Results and Discussion The Au-SPE/oPDA devices displayed linear responses to Breast Tumour Antigen both in EIS and SWV assays, down to 0.5 U/mL and 10.0 U/mL, respectively, with detection limits of 40.0 and 0.005 U/mL. Further tests are progressing and point out that the here described sensor seems a promising tool for screening Breast Tumour Antigen in point-of-care, due the simplicity of fabrication, reusability, low time response, low cost, good sensitivity and selectivity. Acknowledgements The authors acknowledge the financial support of European Research Council though the Starting Grant, ERC-StG-3P’s/2012, GA 311086 (to MGF Sales). |
LAANA Truta, MGF Sales Sol-gel biomimetic material designed to target CEA cancer biomarker (Conference) Poster (J3), First ASPIC International Conference, the Portuguese Association of Cancer Research, Fundação Calouste Gulbenkian, Lisboa, Portugal, 2014. @conference{Truta2014b, title = {Sol-gel biomimetic material designed to target CEA cancer biomarker}, author = {LAANA Truta and MGF Sales}, year = {2014}, date = {2014-11-25}, address = {Fundação Calouste Gulbenkian, Lisboa, Portugal}, organization = {Poster (J3), First ASPIC International Conference, the Portuguese Association of Cancer Research,}, abstract = {Introduction Carcinoembryonic antigen (CEA) is an important tumor marker responsible for clinical diagnosis of over 95% of all colon tumors, 50% of breast tumors, as well as tumors of the lung cancer or ovarian carcinoma [1]. The detection of CEA levels in biological samples plays an important role in the pre-diagnosis evaluation and in the follow-up examination during therapy stage [2]. The most common tool for the analysis of CEA in hospitals and clinical laboratories relies on ELISA-based procedures using antibodies as capturing probe. The overall principal offers the selectivity and sensitivity out coming from the use of antibodies, but it could be further improved by assembling the biosensors over a receptor platform and establishing a label-free measure by electrical impedance spectroscopy (EIS). Thus, the present work proposes the development of an immunosensor for CEA. Materials and Methods Electrochemical signals were measured in a Methrom Autolab potentiostat/galvanostat (Autolab PGSTAT302N) interfaced to a computer and controlled by NOVA 1.9 software. The chemical modification of the surface of the conductive glass was characterized by Raman spectroscopy with confocal microscopy (Thermo Scientific). The immunosensor was assembled by modifying conductive glass (with ITO) with an amino silane compound (APTES), activating the antibody via carbodiimide chemistry (EDAC/NHS) and binding the antibody to the amine surface over the ITO glass. The performance of the imunosensor was evaluated by electrochemical techniques, namely electrochemical impedance spectroscopy (EIS) and square wave voltammetry (SVW). Results and discussion The immunosensor made with an optimized composition displayed linear behavior against CEA concentration by EIS and SWV techniques. The corresponding linear ranges were 0.502-1.5 and 0.252- 1.5ng/mL, with detection limits of 0.417 and 0.043 ng/mL, respectively. Overall, the obtained device may be potential method to apply for screening CEA in point-of-care due to the simplicity of fabrication, short time response, low cost and good sensitivity when compared to other analytical techniques, such as ELISA assays. [1] Kemmegne-Mbouguen, J. et al., 2014, Int. J. Electrochem. Sci., 9, 478 – 492. [2] Liua, M. et al., 2010, Talanta, 81, 1625–1629. Keywords: Cancer biomarker, CEA, antibody, biosensors, sol-gel. Acknowledgements: This work had the financial support of 3P’s Starting Grant/ERC (GA 311086).}, keywords = {}, pubstate = {published}, tppubtype = {conference} } Introduction Carcinoembryonic antigen (CEA) is an important tumor marker responsible for clinical diagnosis of over 95% of all colon tumors, 50% of breast tumors, as well as tumors of the lung cancer or ovarian carcinoma [1]. The detection of CEA levels in biological samples plays an important role in the pre-diagnosis evaluation and in the follow-up examination during therapy stage [2]. The most common tool for the analysis of CEA in hospitals and clinical laboratories relies on ELISA-based procedures using antibodies as capturing probe. The overall principal offers the selectivity and sensitivity out coming from the use of antibodies, but it could be further improved by assembling the biosensors over a receptor platform and establishing a label-free measure by electrical impedance spectroscopy (EIS). Thus, the present work proposes the development of an immunosensor for CEA. Materials and Methods Electrochemical signals were measured in a Methrom Autolab potentiostat/galvanostat (Autolab PGSTAT302N) interfaced to a computer and controlled by NOVA 1.9 software. The chemical modification of the surface of the conductive glass was characterized by Raman spectroscopy with confocal microscopy (Thermo Scientific). The immunosensor was assembled by modifying conductive glass (with ITO) with an amino silane compound (APTES), activating the antibody via carbodiimide chemistry (EDAC/NHS) and binding the antibody to the amine surface over the ITO glass. The performance of the imunosensor was evaluated by electrochemical techniques, namely electrochemical impedance spectroscopy (EIS) and square wave voltammetry (SVW). Results and discussion The immunosensor made with an optimized composition displayed linear behavior against CEA concentration by EIS and SWV techniques. The corresponding linear ranges were 0.502-1.5 and 0.252- 1.5ng/mL, with detection limits of 0.417 and 0.043 ng/mL, respectively. Overall, the obtained device may be potential method to apply for screening CEA in point-of-care due to the simplicity of fabrication, short time response, low cost and good sensitivity when compared to other analytical techniques, such as ELISA assays. [1] Kemmegne-Mbouguen, J. et al., 2014, Int. J. Electrochem. Sci., 9, 478 – 492. [2] Liua, M. et al., 2010, Talanta, 81, 1625–1629. Keywords: Cancer biomarker, CEA, antibody, biosensors, sol-gel. Acknowledgements: This work had the financial support of 3P’s Starting Grant/ERC (GA 311086). |
L Brandão, C Hora, MGF Sales Autonomous electrochemical biosensor for cancer screening (Conference) Oral presentation (SI4), First ASPIC International Conference, the Portuguese Association of Cancer Research, Fundação Calouste Gulbenkian, Lisboa, Portugal, 2014. @conference{Brandão2014, title = {Autonomous electrochemical biosensor for cancer screening}, author = {L Brandão and C Hora and MGF Sales}, year = {2014}, date = {2014-11-25}, address = {Fundação Calouste Gulbenkian, Lisboa, Portugal}, organization = {Oral presentation (SI4), First ASPIC International Conference, the Portuguese Association of Cancer Research,}, abstract = {Introduction State-of-art electrical biosensors for cancer biomarkers present electrical dependency features, in order to transduce the biorecognition event into an electrical signal. The electrical dependency of such biosensor can be eliminated by coupling the bioreceptor to a transducer that is capable of autonomous energy production, for instance a solar cell. Such strategy would allow the production of a cancer screening sensor fully independent, simple and low cost. In this work, a dye sensitized solar cell (DSSC) was used as the autonomous transducer of an electrochemical biosensor for the carcinoembryonic antigen (CEA) cancer biomarker. Materials and methods Surface imprinting was used for preparing molecularly imprinted polymers (MIP) for carcinoembryonic antigen (CEA) on the DSSC counter-electrode. A monolayer of the template protein was adsorbed on the Pt surface and surface imprinting was performed by electropolymerization of phenol red. Different electropolymerization times were considered to control film thickness in order to not overlay the template protein and sterically hinder its removal for creating the negative imprinted sites. Film thicknesses were controlled by the charge passed through the electrode and by ellipsometry. The template protein was removed from the imprinted sites by potential sweep in acidic media. Initial characterization of the biosensor was made by electrochemical impedance spectroscopy (EIS) in a three electrode configuration cell, using I-/I3 - in PBS as redox probe. The biosensor was incubated with increasing concentrations of the target biomarker and the signal obtained by EIS during probe reduction was plotted against protein concentration. Following, a DSSC was assembled with the MIP modified counter electrode and the autonomous biosensor was tested with increasing concentrations of CEA. After each incubation step the DSSC was closed and the energy conversion characterization performed under 1 sun illumination equivalent. Results and discussion Preliminary results indicate that the electrical power produced by the DSSC decreased with concentration of CEA. This effect was related to the rebinding of the CEA biomarker on the imprinted molds that hindered by steric hindrance the counter electrode below. Because of that the catalytic actives sites are not available to catalyze the I3 - reduction what decreases light conversion. Acknowledgments Authors acknowledge funding from the ERC Starting Grant project “3P´s”.}, keywords = {}, pubstate = {published}, tppubtype = {conference} } Introduction State-of-art electrical biosensors for cancer biomarkers present electrical dependency features, in order to transduce the biorecognition event into an electrical signal. The electrical dependency of such biosensor can be eliminated by coupling the bioreceptor to a transducer that is capable of autonomous energy production, for instance a solar cell. Such strategy would allow the production of a cancer screening sensor fully independent, simple and low cost. In this work, a dye sensitized solar cell (DSSC) was used as the autonomous transducer of an electrochemical biosensor for the carcinoembryonic antigen (CEA) cancer biomarker. Materials and methods Surface imprinting was used for preparing molecularly imprinted polymers (MIP) for carcinoembryonic antigen (CEA) on the DSSC counter-electrode. A monolayer of the template protein was adsorbed on the Pt surface and surface imprinting was performed by electropolymerization of phenol red. Different electropolymerization times were considered to control film thickness in order to not overlay the template protein and sterically hinder its removal for creating the negative imprinted sites. Film thicknesses were controlled by the charge passed through the electrode and by ellipsometry. The template protein was removed from the imprinted sites by potential sweep in acidic media. Initial characterization of the biosensor was made by electrochemical impedance spectroscopy (EIS) in a three electrode configuration cell, using I-/I3 - in PBS as redox probe. The biosensor was incubated with increasing concentrations of the target biomarker and the signal obtained by EIS during probe reduction was plotted against protein concentration. Following, a DSSC was assembled with the MIP modified counter electrode and the autonomous biosensor was tested with increasing concentrations of CEA. After each incubation step the DSSC was closed and the energy conversion characterization performed under 1 sun illumination equivalent. Results and discussion Preliminary results indicate that the electrical power produced by the DSSC decreased with concentration of CEA. This effect was related to the rebinding of the CEA biomarker on the imprinted molds that hindered by steric hindrance the counter electrode below. Because of that the catalytic actives sites are not available to catalyze the I3 - reduction what decreases light conversion. Acknowledgments Authors acknowledge funding from the ERC Starting Grant project “3P´s”. |
MGF Sales New biosensors to monitor cancer biomarkers (Conference) Invited Speaker (SII), First ASPIC International Conference, the Portuguese Association of Cancer Research, Fundação Calouste Gulbenkian, Lisboa, Portugal, 2014. (BibTeX) @conference{Sales2014, title = {New biosensors to monitor cancer biomarkers}, author = {MGF Sales}, year = {2014}, date = {2014-11-25}, address = {Fundação Calouste Gulbenkian, Lisboa, Portugal}, organization = {Invited Speaker (SII), First ASPIC International Conference, the Portuguese Association of Cancer Research,}, keywords = {}, pubstate = {published}, tppubtype = {conference} } |
MGF Sales Nanomaterials and biomimetics applied (Conference) Invited Speaker, Facultat de Química, Escola Tècnica Superior de Enginyeria Química, Universitat Rovira I Virgili, Tarragona, Espanha, 2014. (BibTeX) @conference{Sales2014b, title = {Nanomaterials and biomimetics applied}, author = {MGF Sales}, year = {2014}, date = {2014-11-20}, address = {Universitat Rovira I Virgili, Tarragona, Espanha}, organization = {Invited Speaker, Facultat de Química, Escola Tècnica Superior de Enginyeria Química,}, keywords = {}, pubstate = {published}, tppubtype = {conference} } |
MGF Sales Towards cancer diagnosis in point-of-care (Conference) Invited Speaker, 4PYChem, 4th Portuguese Young Chemists Meeting, Excellence in Sustainable Chemistry Session sponsored by SOLCHEMAR, Universidade de Coimbra, Portugal, 2014. (BibTeX) @conference{Sales2014b, title = {Towards cancer diagnosis in point-of-care}, author = {MGF Sales}, year = {2014}, date = {2014-05-01}, address = {Universidade de Coimbra, Portugal}, organization = {Invited Speaker, 4PYChem, 4th Portuguese Young Chemists Meeting, Excellence in Sustainable Chemistry Session sponsored by SOLCHEMAR,}, keywords = {}, pubstate = {published}, tppubtype = {conference} } |
MGF Sales Biosensors with protein-imprinted materials (Conference) Invited Speaker (I-11)SPQ-Analítica. Symposium of the Analytical Division of the Portuguese Society of Chemistry, Coimbra, Portugal, 2014. (BibTeX) @conference{Sales2014b, title = {Biosensors with protein-imprinted materials}, author = {MGF Sales}, year = {2014}, date = {2014-04-14}, address = {Coimbra, Portugal}, organization = {Invited Speaker (I-11)SPQ-Analítica. Symposium of the Analytical Division of the Portuguese Society of Chemistry,}, keywords = {}, pubstate = {published}, tppubtype = {conference} } |
JRL Guerreiro, M Frederiksen, VE Bochenkov, VAP Freitas, MGF Sales, DS Sutherland Astringency estimation by localized surface plasmon resonance (Conference) Oral presentation, NanoPT, NanoPorTugal International Conference, Alfândega, Porto, Portugal, 2014. @conference{Guerreiro2014, title = {Astringency estimation by localized surface plasmon resonance}, author = {JRL Guerreiro and M Frederiksen and VE Bochenkov and VAP Freitas and MGF Sales and DS Sutherland}, year = {2014}, date = {2014-02-12}, address = {Alfândega, Porto, Portugal}, organization = {Oral presentation, NanoPT, NanoPorTugal International Conference,}, abstract = {The popularity of phenolic compounds has increased in the past years due to their antioxidant capacity and association for the prevention of heart diseases 1, chronic inflammation 2 and cancer 3. Human diet is the main source of polyphenols provided by products derivate from plants such as fruits, vegetables and beverages, and the long term consumption suggests a contribution for potential health benefits. In addition, polyphenols also contribute for the sensorial perception of food products being astringency one of the known sensory characteristics. Astringency is a mechanism that is still not fully understood. Nevertheless, several studies support the concept that astringency is a tactile sensation rather than a taste. The astringency mechanism is thought to be caused by the polyphenols ability to bind salivary proteins, thus forming complexes that lead to precipitation by promoting the dryness roughening and pucker typical perceived. Furthermore astringency is also an important parameter used to determine the wine quality and it is usually estimated based on sensorial panels which are expensive, time consuming and conferring a certain subjectivity to the process 4. In order to overcome these disadvantages, a label free sensory system was performed based on localized surface plasmon resonance (LSPR) by detecting the interaction between a salivary protein and the polyphenols, mimicking the natural interaction which occurs in the mouth. The LSPR is a powerful tool because the metallic nanostructures can be excited by incident light, thereby promoting a collective oscillation of the conduction electrons at a specific wavelength. Structural changes in the local refractive index are induced, when the target molecules bind to the receptor on the surface of a nanoplasmonic, those being tracked by the monitorization of variations at the correspondent wavelength of maximum extinction. The nanostructures used in this work were gold nanodisks attached to a glass surface fabricated by sparse colloidal lithography. The substrates were prepared according to the following steps : i) cleaning the glass coverslips; ii) spin coating of PMMA, followed by 2 min. in a hot plate; iii) deposition of a triple layer of polyelectrolytes for 30 min each followed by the deposition of polystyrene particles 100 nm size; iv) deposition of 20 nm Ti as a mask; v) removal of particles by tape stripping followed by etching for 10 min vi) deposition of 2 nm Ti and 20 nm Au followed by acetone rising. The resultant nanostructures were gold nanodisks as shown in figure 1. After the fabrication of gold disks, b-amylase was immobilized on the gold surface according to the optimal conditions previously tested, and the subsequent interaction with pentagalloyl glucose (PGG) was measured by LSPR. The interacting between the polyphenol PGG and the immobilized alpha-amylase displayed a red shift in the spectra which kept shifting with the increasing of PGG concentration as can be seen in figure 2. The interaction between the polyphenol and the salivary protein provided a linear behavior for a concentration range from 0.5 to 155 μM of PGG, which can be seen in figure 3. Red wine samples which were previously analyzed by a sensory panel were also measured and classified in terms of astringency. The wine astringency presented the same order of astringency levels when compared with the sensory panel, indicating the close agreement between both methodologies. Therefore the proposed sensor offers a simple approach for the estimation astringency based on protein-polyphenol interaction, being the application to real samples successful. Additionally the LSPR nanostructure enhanced the sensing ability and included a simple fabrication due to the recent advances in nanotechnology.}, keywords = {}, pubstate = {published}, tppubtype = {conference} } The popularity of phenolic compounds has increased in the past years due to their antioxidant capacity and association for the prevention of heart diseases 1, chronic inflammation 2 and cancer 3. Human diet is the main source of polyphenols provided by products derivate from plants such as fruits, vegetables and beverages, and the long term consumption suggests a contribution for potential health benefits. In addition, polyphenols also contribute for the sensorial perception of food products being astringency one of the known sensory characteristics. Astringency is a mechanism that is still not fully understood. Nevertheless, several studies support the concept that astringency is a tactile sensation rather than a taste. The astringency mechanism is thought to be caused by the polyphenols ability to bind salivary proteins, thus forming complexes that lead to precipitation by promoting the dryness roughening and pucker typical perceived. Furthermore astringency is also an important parameter used to determine the wine quality and it is usually estimated based on sensorial panels which are expensive, time consuming and conferring a certain subjectivity to the process 4. In order to overcome these disadvantages, a label free sensory system was performed based on localized surface plasmon resonance (LSPR) by detecting the interaction between a salivary protein and the polyphenols, mimicking the natural interaction which occurs in the mouth. The LSPR is a powerful tool because the metallic nanostructures can be excited by incident light, thereby promoting a collective oscillation of the conduction electrons at a specific wavelength. Structural changes in the local refractive index are induced, when the target molecules bind to the receptor on the surface of a nanoplasmonic, those being tracked by the monitorization of variations at the correspondent wavelength of maximum extinction. The nanostructures used in this work were gold nanodisks attached to a glass surface fabricated by sparse colloidal lithography. The substrates were prepared according to the following steps : i) cleaning the glass coverslips; ii) spin coating of PMMA, followed by 2 min. in a hot plate; iii) deposition of a triple layer of polyelectrolytes for 30 min each followed by the deposition of polystyrene particles 100 nm size; iv) deposition of 20 nm Ti as a mask; v) removal of particles by tape stripping followed by etching for 10 min vi) deposition of 2 nm Ti and 20 nm Au followed by acetone rising. The resultant nanostructures were gold nanodisks as shown in figure 1. After the fabrication of gold disks, b-amylase was immobilized on the gold surface according to the optimal conditions previously tested, and the subsequent interaction with pentagalloyl glucose (PGG) was measured by LSPR. The interacting between the polyphenol PGG and the immobilized alpha-amylase displayed a red shift in the spectra which kept shifting with the increasing of PGG concentration as can be seen in figure 2. The interaction between the polyphenol and the salivary protein provided a linear behavior for a concentration range from 0.5 to 155 μM of PGG, which can be seen in figure 3. Red wine samples which were previously analyzed by a sensory panel were also measured and classified in terms of astringency. The wine astringency presented the same order of astringency levels when compared with the sensory panel, indicating the close agreement between both methodologies. Therefore the proposed sensor offers a simple approach for the estimation astringency based on protein-polyphenol interaction, being the application to real samples successful. Additionally the LSPR nanostructure enhanced the sensing ability and included a simple fabrication due to the recent advances in nanotechnology. |
LAANA Truta, MGF Sales A disposable glass-based immunosensor for monitoring the cancer biomarker CEA in urine (Conference) Poster, NanoPT, NanoPorTugal International Conference, Alfândega, Porto, Portugal, 2014. @conference{Truta2014b, title = {A disposable glass-based immunosensor for monitoring the cancer biomarker CEA in urine}, author = {LAANA Truta and MGF Sales}, year = {2014}, date = {2014-02-12}, address = {Alfândega, Porto, Portugal}, organization = {Poster, NanoPT, NanoPorTugal International Conference,}, abstract = {Immunosensing is a fast and cost-effective method in clinical diagnosis, relying on antibody-antigen interaction for the quantitative detection a specific antigen. Different types of antigen species have been screened in this context, including tumor markers, assessed by enzyme-linked immunosorbent, chemiluminescence and electrochemical methods1. Tumor markers are biomolecules in tumor cells or body fluids that may be associated with cancer diseases. Carcinoembryonic antigen (CEA) is among such markers, being employed in clinical diagnosis of over 80% colorectal cancers, with relatively little expression in normal mucosa2,3. Fast determination of CEA at low cost is presently required, to enable its use over wide screening programs and application in point-of-care context. This work presents a new simple immunoassay method for CEA detection in urine using a disposable glass-based immunosensor coupled to electrochemical detection. Conductive glass covered by fluorine doped tin oxide (FTO) was used as conductive support and modified with anti-CEA by means of bottom-up approach. All stages involved in the biochemical modification were followed by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). The analytical performance of the device was fully characterized by EIS, proving sensitive readings of CEA from 2.5x10-3 to 0.10 ng/mL. The immunosensor was applied to real urine analysis from healthy individual spiked with the antigen. Overall, the combination of the sensory material with electrode design has lead to a promising tool for point-of-care applications, when applied to field monitoring of CEA in urine samples.}, keywords = {}, pubstate = {published}, tppubtype = {conference} } Immunosensing is a fast and cost-effective method in clinical diagnosis, relying on antibody-antigen interaction for the quantitative detection a specific antigen. Different types of antigen species have been screened in this context, including tumor markers, assessed by enzyme-linked immunosorbent, chemiluminescence and electrochemical methods1. Tumor markers are biomolecules in tumor cells or body fluids that may be associated with cancer diseases. Carcinoembryonic antigen (CEA) is among such markers, being employed in clinical diagnosis of over 80% colorectal cancers, with relatively little expression in normal mucosa2,3. Fast determination of CEA at low cost is presently required, to enable its use over wide screening programs and application in point-of-care context. This work presents a new simple immunoassay method for CEA detection in urine using a disposable glass-based immunosensor coupled to electrochemical detection. Conductive glass covered by fluorine doped tin oxide (FTO) was used as conductive support and modified with anti-CEA by means of bottom-up approach. All stages involved in the biochemical modification were followed by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). The analytical performance of the device was fully characterized by EIS, proving sensitive readings of CEA from 2.5x10-3 to 0.10 ng/mL. The immunosensor was applied to real urine analysis from healthy individual spiked with the antigen. Overall, the combination of the sensory material with electrode design has lead to a promising tool for point-of-care applications, when applied to field monitoring of CEA in urine samples. |
2013
APM Tavares, FTC Moreira, MGF Sales Haemoglobin smart plastic antibody material tailored with charged binding sites on silica nanoparticles: Its application as ionophore in potentiometric transduction (Conference) Poster (P31), III Jornadas Eletroquimica e Inovação, Universidade de Trás-os-Montes e Alto Douro (UTAD), Vila Real, Portugal, 2013. @conference{Tavares2013b, title = {Haemoglobin smart plastic antibody material tailored with charged binding sites on silica nanoparticles: Its application as ionophore in potentiometric transduction}, author = {APM Tavares and FTC Moreira and MGF Sales}, year = {2013}, date = {2013-09-16}, address = {Universidade de Trás-os-Montes e Alto Douro (UTAD), Vila Real, Portugal}, organization = {Poster (P31), III Jornadas Eletroquimica e Inovação,}, abstract = {Human hemoglobin (Hb) is a globular metalloprotein, present in the blood and involved in gas transport. Hb-associated disturbances are related to several diseases, such thalassemia, anemia, heart disease and leukemia, or to side-effects from other diseases, such as cancer. Overall, it is of great importance to know the concentration of Hb in the blood in many health-related conditions. There are many methods described in the literature for determining Hb. Most of these rely on antibody/antigen interactions, due to the high selectivity of the affinity reaction taking place between these biomolecules. However, the use of antibodies for Hb determination in routine clinical use is very expensive, due to the high cost of the material, the need for special handling and storage, and the non-reusability. These constraints may be limited by replacing natural antibodies by plastic receptors, obtained by molecular imprinting procedures. Thus, this work describes a novel smart plastic antibody material (SPAM) by surface imprinting technique for the detection of Hb and its application to design small, portable and low cost potentiometric devices. The SPAM material was obtained by linking Hb to silica nanoparticles and allowing its subsequent interaction with different vinyl monomers, of different chemical functions and ionic charges. Control materials were designed in parallel to assess the ability of establishing stereochemical recognition of Hb and the effect of the kind/charge of the monomers employed. Scanning Electron Microscopy analysis confirmed the surface modification of the silica material used for imprint. All materials were mixed with PVC/plasticizer and applied as selective membranes in potentiometric transduction. Suitable emf variations were detected only for selective membranes having a SPAM material and a charged lipophilic anionic additive. All control materials were unable to produce a potentiometric response. Overall, good features were obtained for SPAM-based selective membranes carrying an anionic lipophilic additive. In HEPES buffer of pH 5, limits of detection were 43.8μg/mL for a linear response after 83.8μg/mL with a cationic slope of +40.4mV/decade. Good selectivity was also observed against other coexisting biomolecules. The analytical application was conducted successfully, showing accurate and precise results.}, keywords = {}, pubstate = {published}, tppubtype = {conference} } Human hemoglobin (Hb) is a globular metalloprotein, present in the blood and involved in gas transport. Hb-associated disturbances are related to several diseases, such thalassemia, anemia, heart disease and leukemia, or to side-effects from other diseases, such as cancer. Overall, it is of great importance to know the concentration of Hb in the blood in many health-related conditions. There are many methods described in the literature for determining Hb. Most of these rely on antibody/antigen interactions, due to the high selectivity of the affinity reaction taking place between these biomolecules. However, the use of antibodies for Hb determination in routine clinical use is very expensive, due to the high cost of the material, the need for special handling and storage, and the non-reusability. These constraints may be limited by replacing natural antibodies by plastic receptors, obtained by molecular imprinting procedures. Thus, this work describes a novel smart plastic antibody material (SPAM) by surface imprinting technique for the detection of Hb and its application to design small, portable and low cost potentiometric devices. The SPAM material was obtained by linking Hb to silica nanoparticles and allowing its subsequent interaction with different vinyl monomers, of different chemical functions and ionic charges. Control materials were designed in parallel to assess the ability of establishing stereochemical recognition of Hb and the effect of the kind/charge of the monomers employed. Scanning Electron Microscopy analysis confirmed the surface modification of the silica material used for imprint. All materials were mixed with PVC/plasticizer and applied as selective membranes in potentiometric transduction. Suitable emf variations were detected only for selective membranes having a SPAM material and a charged lipophilic anionic additive. All control materials were unable to produce a potentiometric response. Overall, good features were obtained for SPAM-based selective membranes carrying an anionic lipophilic additive. In HEPES buffer of pH 5, limits of detection were 43.8μg/mL for a linear response after 83.8μg/mL with a cationic slope of +40.4mV/decade. Good selectivity was also observed against other coexisting biomolecules. The analytical application was conducted successfully, showing accurate and precise results. |
FTC Moreira, S Sharma, RAF Dutra, JPC Noronha, AEG Cass, MGF Sales A biomimetic biosensor based on poly(o-aminophenol) film for cardiac biomarker detection in point-of-care (Conference) Poster (P29), III Jornadas Eletroquimica e Inovação, Universidade de Trás-os-Montes e Alto Douro (UTAD), Vila Real, Portugal, 2013. @conference{Moreira2013b, title = {A biomimetic biosensor based on poly(o-aminophenol) film for cardiac biomarker detection in point-of-care}, author = {FTC Moreira and S Sharma and RAF Dutra and JPC Noronha and AEG Cass and MGF Sales}, year = {2013}, date = {2013-09-16}, address = {Universidade de Trás-os-Montes e Alto Douro (UTAD), Vila Real, Portugal}, organization = {Poster (P29), III Jornadas Eletroquimica e Inovação,}, abstract = {Acute coronary syndrome (ACS) is a spectrum of acute myocardial ischemia spanning from unstable angina to acute myocardial infarction (AMI). Patients under AMI require from emergency medical assistance a quick diagnosis, but symptoms of chest pain, pressure, shortness of breath, and/or nausea are common to acute myocardial ischemia conditions. Myoglobin (Myo) is a nonspecific biomarker that appears in the peripheral circulation as early as 1 to 2 hours after cardiac damage. Quick and low-cost methods for Myo detection/determination in point-of-care are therefore appreciated. This work describes for this purpose an electropolymerized molecular imprinting (EMI) polymer film for Myo detection in ischemic episodes. The EMI is composed with Myo and aminophenol (AP) monomer deposited on gold screen printed electrode surface (Au-SPE). Myo was removed from the polymeric matrix was with proteinase K. A nonimprinted material (NI) was synthesized by following the same procedure without having a template. This material was used as a negative control. Atomic Force Microscopy and RAMAN Spectroscopy analysis confirmed the surface modification of the working area in the Au-SPE. The ability of the biomaterial EMI and its negative control NI to rebind Myo on the Au-SPE support was followed electrochemically. Electrochemical Impedance Spectroscopy (EIS) and Square Wave Voltammetry (SWV) were used for this purpose. The NI/Au-SPE was unable to interact with Myo in a predicted way, showing a similar-to-random behavior. EMI/Au-SPE devices displayed an opposite behavior, showing linear responses to Myo down to 3.5 g/mL or 0.58 g/mL in EIS or SWV assays, respectively. The corresponding detection limits were 1.5 μg/mL or 0.28 μg/mL. EMI also showed negligible interference from troponin T, bovine serum albumin and urea under SWV assays, showing promising results for point-of-care applications when applied to spiked biological fluids.}, keywords = {}, pubstate = {published}, tppubtype = {conference} } Acute coronary syndrome (ACS) is a spectrum of acute myocardial ischemia spanning from unstable angina to acute myocardial infarction (AMI). Patients under AMI require from emergency medical assistance a quick diagnosis, but symptoms of chest pain, pressure, shortness of breath, and/or nausea are common to acute myocardial ischemia conditions. Myoglobin (Myo) is a nonspecific biomarker that appears in the peripheral circulation as early as 1 to 2 hours after cardiac damage. Quick and low-cost methods for Myo detection/determination in point-of-care are therefore appreciated. This work describes for this purpose an electropolymerized molecular imprinting (EMI) polymer film for Myo detection in ischemic episodes. The EMI is composed with Myo and aminophenol (AP) monomer deposited on gold screen printed electrode surface (Au-SPE). Myo was removed from the polymeric matrix was with proteinase K. A nonimprinted material (NI) was synthesized by following the same procedure without having a template. This material was used as a negative control. Atomic Force Microscopy and RAMAN Spectroscopy analysis confirmed the surface modification of the working area in the Au-SPE. The ability of the biomaterial EMI and its negative control NI to rebind Myo on the Au-SPE support was followed electrochemically. Electrochemical Impedance Spectroscopy (EIS) and Square Wave Voltammetry (SWV) were used for this purpose. The NI/Au-SPE was unable to interact with Myo in a predicted way, showing a similar-to-random behavior. EMI/Au-SPE devices displayed an opposite behavior, showing linear responses to Myo down to 3.5 g/mL or 0.58 g/mL in EIS or SWV assays, respectively. The corresponding detection limits were 1.5 μg/mL or 0.28 μg/mL. EMI also showed negligible interference from troponin T, bovine serum albumin and urea under SWV assays, showing promising results for point-of-care applications when applied to spiked biological fluids. |
LAANA Truta, NS Ferreira, MGF Sales Carnitine tailored sensors on surface molecular imprinting based on graphene layer (Conference) Poster (P32), III Jornadas Eletroquimica e Inovação, Universidade de Trás-os-Montes e Alto Douro (UTAD), Vila Real, Portugal, 2013. @conference{Truta2013, title = {Carnitine tailored sensors on surface molecular imprinting based on graphene layer}, author = {LAANA Truta and NS Ferreira and MGF Sales}, year = {2013}, date = {2013-09-16}, address = {Universidade de Trás-os-Montes e Alto Douro (UTAD), Vila Real, Portugal}, organization = {Poster (P32), III Jornadas Eletroquimica e Inovação,}, abstract = {A new biosensor based on surface molecularly imprinted polymer (MIP) on graphene layers was successfully developed. It consists in a 3D polymeric network created on top of surface and around the target template, Carnitine (CRT), a potential biomarker of ovary cancer. The polymeric structure was obtained after radical polymerization of (vinylbenzyl)trimethylammonium chloride, 4-styrenesulfonic acid and vinyl pivalate, including in the reaction mixture ethylene glycol dimethacrylate as cross-linker and ammonium persulphate as initiator. Non-imprinted polymer (NIP) material was also produced, by excluding the template from the procedure. The imprinted graphene structures were further used for the selective determination of CRT by potentiometric transduction. For this purpose, a selective membrane was prepared by using the MIP material as ionophore, and dispersing it in a plasticized poly(vinylchloride) matrix, that included (or not) a suitable amount of charged lipophilic additive. The membranes were casted over a solid conductive support, made of graphite or of conductive glass. Control membranes were also produced by replacing MIP by NIP material. The potentiometric performance of the above electrodes was assessed against CRT solutions of increasing concentrations. Graphite supports displayed the best analytical features, with average slope and detection limit of 40.51 mVdecade-1 and 3.55x10-6 molL-1, respectively. The effect of pH upon the potentiometric response was evaluated for different buffer solutions (within 2-9) and the best performance for this sensor was obtained with HEPES (4-(2-hydroxyethyl)-1- piperazineethanesulfonic acid) buffer of pH 5.2. The interference effect of albumin, ascorbic acid, glucose, creatinine and urea in the performance of the electrochemical unit was tested for concentrations up to their normal physiologic levels in urine and good selectivity was observed. The application of the devices to the analysis of spiked samples showed recoveries ranging from 91% (± 6.8%) to 118% (± 11.2%), with relative errors below -20%. Overall, the combination of the MIP sensory material with a suitable selective membrane and electrode design showed to be a promising tool for point-of-care applications.}, keywords = {}, pubstate = {published}, tppubtype = {conference} } A new biosensor based on surface molecularly imprinted polymer (MIP) on graphene layers was successfully developed. It consists in a 3D polymeric network created on top of surface and around the target template, Carnitine (CRT), a potential biomarker of ovary cancer. The polymeric structure was obtained after radical polymerization of (vinylbenzyl)trimethylammonium chloride, 4-styrenesulfonic acid and vinyl pivalate, including in the reaction mixture ethylene glycol dimethacrylate as cross-linker and ammonium persulphate as initiator. Non-imprinted polymer (NIP) material was also produced, by excluding the template from the procedure. The imprinted graphene structures were further used for the selective determination of CRT by potentiometric transduction. For this purpose, a selective membrane was prepared by using the MIP material as ionophore, and dispersing it in a plasticized poly(vinylchloride) matrix, that included (or not) a suitable amount of charged lipophilic additive. The membranes were casted over a solid conductive support, made of graphite or of conductive glass. Control membranes were also produced by replacing MIP by NIP material. The potentiometric performance of the above electrodes was assessed against CRT solutions of increasing concentrations. Graphite supports displayed the best analytical features, with average slope and detection limit of 40.51 mVdecade-1 and 3.55x10-6 molL-1, respectively. The effect of pH upon the potentiometric response was evaluated for different buffer solutions (within 2-9) and the best performance for this sensor was obtained with HEPES (4-(2-hydroxyethyl)-1- piperazineethanesulfonic acid) buffer of pH 5.2. The interference effect of albumin, ascorbic acid, glucose, creatinine and urea in the performance of the electrochemical unit was tested for concentrations up to their normal physiologic levels in urine and good selectivity was observed. The application of the devices to the analysis of spiked samples showed recoveries ranging from 91% (± 6.8%) to 118% (± 11.2%), with relative errors below -20%. Overall, the combination of the MIP sensory material with a suitable selective membrane and electrode design showed to be a promising tool for point-of-care applications. |
NS Ferreira, MGF Sales Disposable immunosensor with simple antibody orientation for label-free real-time detection of a cancer biomarker (Conference) Poster (P30), III Jornadas Eletroquimica e Inovação, Universidade de Trás-os-Montes e Alto Douro (UTAD), Vila Real, Portugal, 2013. @conference{Ferreira2013, title = {Disposable immunosensor with simple antibody orientation for label-free real-time detection of a cancer biomarker}, author = {NS Ferreira and MGF Sales}, year = {2013}, date = {2013-09-16}, address = {Universidade de Trás-os-Montes e Alto Douro (UTAD), Vila Real, Portugal}, organization = {Poster (P30), III Jornadas Eletroquimica e Inovação,}, abstract = {Human hemoglobin (Hb) is a globular metalloprotein, present in the blood and involved in gas transport. Hb-associated disturbances are related to several diseases, such thalassemia, anemia, heart disease and leukemia, or to side-effects from other diseases, such as cancer. Overall, it is of great importance to know the concentration of Hb in the blood in many health-related conditions. There are many methods described in the literature for determining Hb. Most of these rely on antibody/antigen interactions, due to the high selectivity of the affinity reaction taking place between these biomolecules. However, the use of antibodies for Hb determination in routine clinical use is very expensive, due to the high cost of the material, the need for special handling and storage, and the non-reusability. These constraints may be limited by replacing natural antibodies by plastic receptors, obtained by molecular imprinting procedures. Thus, this work describes a novel smart plastic antibody material (SPAM) by surface imprinting technique for the detection of Hb and its application to design small, portable and low cost potentiometric devices. The SPAM material was obtained by linking Hb to silica nanoparticles and allowing its subsequent interaction with different vinyl monomers, of different chemical functions and ionic charges. Control materials were designed in parallel to assess the ability of establishing stereochemical recognition of Hb and the effect of the kind/charge of the monomers employed. Scanning Electron Microscopy analysis confirmed the surface modification of the silica material used for imprint. All materials were mixed with PVC/plasticizer and applied as selective membranes in potentiometric transduction. Suitable emf variations were detected only for selective membranes having a SPAM material and a charged lipophilic anionic additive. All control materials were unable to produce a potentiometric response. Overall, good features were obtained for SPAM-based selective membranes carrying an anionic lipophilic additive. In HEPES buffer of pH 5, limits of detection were 43.8μg/mL for a linear response after 83.8μg/mL with a cationic slope of +40.4mV/decade. Good selectivity was also observed against other coexisting biomolecules. The analytical application was conducted successfully, showing accurate and precise results.}, keywords = {}, pubstate = {published}, tppubtype = {conference} } Human hemoglobin (Hb) is a globular metalloprotein, present in the blood and involved in gas transport. Hb-associated disturbances are related to several diseases, such thalassemia, anemia, heart disease and leukemia, or to side-effects from other diseases, such as cancer. Overall, it is of great importance to know the concentration of Hb in the blood in many health-related conditions. There are many methods described in the literature for determining Hb. Most of these rely on antibody/antigen interactions, due to the high selectivity of the affinity reaction taking place between these biomolecules. However, the use of antibodies for Hb determination in routine clinical use is very expensive, due to the high cost of the material, the need for special handling and storage, and the non-reusability. These constraints may be limited by replacing natural antibodies by plastic receptors, obtained by molecular imprinting procedures. Thus, this work describes a novel smart plastic antibody material (SPAM) by surface imprinting technique for the detection of Hb and its application to design small, portable and low cost potentiometric devices. The SPAM material was obtained by linking Hb to silica nanoparticles and allowing its subsequent interaction with different vinyl monomers, of different chemical functions and ionic charges. Control materials were designed in parallel to assess the ability of establishing stereochemical recognition of Hb and the effect of the kind/charge of the monomers employed. Scanning Electron Microscopy analysis confirmed the surface modification of the silica material used for imprint. All materials were mixed with PVC/plasticizer and applied as selective membranes in potentiometric transduction. Suitable emf variations were detected only for selective membranes having a SPAM material and a charged lipophilic anionic additive. All control materials were unable to produce a potentiometric response. Overall, good features were obtained for SPAM-based selective membranes carrying an anionic lipophilic additive. In HEPES buffer of pH 5, limits of detection were 43.8μg/mL for a linear response after 83.8μg/mL with a cationic slope of +40.4mV/decade. Good selectivity was also observed against other coexisting biomolecules. The analytical application was conducted successfully, showing accurate and precise results. |
APM Tavares, FTC Moreira, MGF Sales Biomimetic biosensor using protein surface imprint on silica spheres coupled with potentiometric transduction for hemoglobin detection (Conference) Poster (P3),5th Graduate Student Symposium on Molecular Imprinting, Queen´s University, Belfast, Reino Unido, 2013. @conference{Tavares2013b, title = {Biomimetic biosensor using protein surface imprint on silica spheres coupled with potentiometric transduction for hemoglobin detection}, author = {APM Tavares and FTC Moreira and MGF Sales}, year = {2013}, date = {2013-08-15}, address = {Queen´s University, Belfast, Reino Unido}, organization = {Poster (P3),5th Graduate Student Symposium on Molecular Imprinting, }, abstract = {A novel protein imprinting approach for hemoglobin (Hb) detection in point-of-care and potentiometric transduction is presented. The imprinted material was created by attaching the protein to a solid support made of silica and labeling the charged sites of the protein with charged monomers: 2-aminoethyl methacrylate hydrochloride (AEMH) and styrene sulfonic acid (SSA). The subsequent stage tailored the binding site with neutral material, by polymerizing styrene and divinylbenzene (DVB). Finally, the template was removed by enzymatic amide cleavage, after treatment with proteinase K. Non imprinted polymer (NI) was synthesized by the same way but without the template. Stereochemical recognition of Hb was confirmed by the non-rebinding capacity displayed by (NI) materials. SEM and FTIR analysis confirmed the surface modification of the silica beads. The biomimetic material was dispersed in plasticized PVC selective membranes and used as ionophores in potentiometric transduction. Good features were obtained in HEPES buffer of pH 5. Under this condition, the limits of detection were 43.8μg/mL for a linear response down to 83.8 μg/L with an anionic slope of -40.3 mV/decade. The analytical application was conducted successfully and showed accurate and precise results.}, keywords = {}, pubstate = {published}, tppubtype = {conference} } A novel protein imprinting approach for hemoglobin (Hb) detection in point-of-care and potentiometric transduction is presented. The imprinted material was created by attaching the protein to a solid support made of silica and labeling the charged sites of the protein with charged monomers: 2-aminoethyl methacrylate hydrochloride (AEMH) and styrene sulfonic acid (SSA). The subsequent stage tailored the binding site with neutral material, by polymerizing styrene and divinylbenzene (DVB). Finally, the template was removed by enzymatic amide cleavage, after treatment with proteinase K. Non imprinted polymer (NI) was synthesized by the same way but without the template. Stereochemical recognition of Hb was confirmed by the non-rebinding capacity displayed by (NI) materials. SEM and FTIR analysis confirmed the surface modification of the silica beads. The biomimetic material was dispersed in plasticized PVC selective membranes and used as ionophores in potentiometric transduction. Good features were obtained in HEPES buffer of pH 5. Under this condition, the limits of detection were 43.8μg/mL for a linear response down to 83.8 μg/L with an anionic slope of -40.3 mV/decade. The analytical application was conducted successfully and showed accurate and precise results. |
FTC Moreira, S Sharma, RAF Dutra, JPC Noronha, AEG Cass, MGF Sales Smart plastic antibody material (SPAM) tailored on disposable screen printed electrodes for protein recognition: application to myoglobin detection (Conference) Oral presentation, 5th Graduate Student Symposium on Molecular Imprinting, Queen´s University, Belfast, Reino Unido, 2013. @conference{Moreira2013b, title = {Smart plastic antibody material (SPAM) tailored on disposable screen printed electrodes for protein recognition: application to myoglobin detection}, author = {FTC Moreira and S Sharma and RAF Dutra and JPC Noronha and AEG Cass and MGF Sales}, year = {2013}, date = {2013-08-15}, address = {Queen´s University, Belfast, Reino Unido}, organization = {Oral presentation, 5th Graduate Student Symposium on Molecular Imprinting, }, abstract = {This work introduces two major changes to the conventional protocol used for designing protein plastic antibodies: (i) the imprinted sites were created with charged monomers while the surrounding environment was tailored using neutral material; (ii) and the protein was removed from its imprinted site by means a protease, aiming at preserving the polymeric network of the plastic antibody. The existence of imprinted sites on the Smart Plastic Antibody Material (SPAM) was checked by comparing a SPAM modified surface to a negative control, NIMs, prepared without target protein. As proof of concept, SPAM was tailored on top of disposable gold-screen printed electrodes (Au-SPE), following a bottom-up approach, for targeting Myoglobin (Myo) in a point-of-care context. All stages involved in the chemical modification of the Ayu layer and leading to the creation of SPAM and NIM materials were followed by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). AFM imaging was also performed to characterize the topography of the surface. The SPAM/Au-SPE devices displayed linear responses to Myo in EIS and SWV assays down to 3.5 μg/mL and 0.58 μg/mL, respectively, with detection limits of 1.5 and 0.28 μg/mL. SPAM materials also showed negligible interference from troponin T (TnT), bovine serum albumin (BSA) and urea under SWV assays, showing promising results for point-of-care applications when applied to spiked biological fluids.}, keywords = {}, pubstate = {published}, tppubtype = {conference} } This work introduces two major changes to the conventional protocol used for designing protein plastic antibodies: (i) the imprinted sites were created with charged monomers while the surrounding environment was tailored using neutral material; (ii) and the protein was removed from its imprinted site by means a protease, aiming at preserving the polymeric network of the plastic antibody. The existence of imprinted sites on the Smart Plastic Antibody Material (SPAM) was checked by comparing a SPAM modified surface to a negative control, NIMs, prepared without target protein. As proof of concept, SPAM was tailored on top of disposable gold-screen printed electrodes (Au-SPE), following a bottom-up approach, for targeting Myoglobin (Myo) in a point-of-care context. All stages involved in the chemical modification of the Ayu layer and leading to the creation of SPAM and NIM materials were followed by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). AFM imaging was also performed to characterize the topography of the surface. The SPAM/Au-SPE devices displayed linear responses to Myo in EIS and SWV assays down to 3.5 μg/mL and 0.58 μg/mL, respectively, with detection limits of 1.5 and 0.28 μg/mL. SPAM materials also showed negligible interference from troponin T (TnT), bovine serum albumin (BSA) and urea under SWV assays, showing promising results for point-of-care applications when applied to spiked biological fluids. |
JRL Guerreiro, VAP Freitas, DS Sutherland, MGF Sales The potential of molecular imprinted combined with plasmonics as a biosensor: Gold nanostructures combined with molecular imprint for biosensing (Conference) Oral presentation, 5th Graduate Student Symposium on Molecular Imprinting, Queen´s University, Belfast, Reino Unido, 2013. @conference{Guerreiro2013b, title = {The potential of molecular imprinted combined with plasmonics as a biosensor: Gold nanostructures combined with molecular imprint for biosensing}, author = {JRL Guerreiro and VAP Freitas and DS Sutherland and MGF Sales}, year = {2013}, date = {2013-08-15}, address = {Queen´s University, Belfast, Reino Unido}, organization = {Oral presentation, 5th Graduate Student Symposium on Molecular Imprinting, }, abstract = {Polyphenols are naturally-occurring compounds, being present in food products deriving from plant sources. Widely known for their antioxidant properties and their role on the prevention of diseases such as cancer, cardiovascular diseases, Alzheimer and many other related with oxidative stress, they have been the target of several studies1. Regarding their biological properties, the polyphenols are also able to interact with biological proteins, integrating part of biological processes. As example, they have the ability of controlling blood pressure or/and haemorrhages or inhibit enzymes2. Polyphenols also interact with salivary proteins, promoting both salivary enzymes inhibition and a strong impact on organoleptic perception. Studying the interaction of polyphenols with proteins can be of great importance in different fields, but sometimes difficult for relying in conventional assays that are often associated with lack of accuracy, high reading times and complex sample manipulation. As a novel approach, this work proposes a combination of molecular imprinting and plasmonic structures to study polyphenol/protein interaction. The optical biosensor is based on the local refractive index sensitivity of gold nanodiscs fabricated using colloidal lithography, which allows rapid fabrication of large areas of defined size for protein binding. After nanofabrication, salivary proteins are bound to gold nanodiscs and this is followed by the synthesis of the molecular imprinted thin film layer around the proteins3. After protein removal, this layer is ready for rebinding salivary proteins and for subsequent interaction with polyphenols. Either proteins or polyphenols when present in the binding sites or surroundings promote a local change in the refractive index changing the properties of the gold nanodiscs, which can be measured by tracking the wavelength shift. Overall, the combination of a nanoplasmonic sensor and the imprinting material offers great chances to create tailored cavities with specific recognition properties, with long shelf life allowing at the same time monitor a specific biorecognition reaction in real-time and label-free.}, keywords = {}, pubstate = {published}, tppubtype = {conference} } Polyphenols are naturally-occurring compounds, being present in food products deriving from plant sources. Widely known for their antioxidant properties and their role on the prevention of diseases such as cancer, cardiovascular diseases, Alzheimer and many other related with oxidative stress, they have been the target of several studies1. Regarding their biological properties, the polyphenols are also able to interact with biological proteins, integrating part of biological processes. As example, they have the ability of controlling blood pressure or/and haemorrhages or inhibit enzymes2. Polyphenols also interact with salivary proteins, promoting both salivary enzymes inhibition and a strong impact on organoleptic perception. Studying the interaction of polyphenols with proteins can be of great importance in different fields, but sometimes difficult for relying in conventional assays that are often associated with lack of accuracy, high reading times and complex sample manipulation. As a novel approach, this work proposes a combination of molecular imprinting and plasmonic structures to study polyphenol/protein interaction. The optical biosensor is based on the local refractive index sensitivity of gold nanodiscs fabricated using colloidal lithography, which allows rapid fabrication of large areas of defined size for protein binding. After nanofabrication, salivary proteins are bound to gold nanodiscs and this is followed by the synthesis of the molecular imprinted thin film layer around the proteins3. After protein removal, this layer is ready for rebinding salivary proteins and for subsequent interaction with polyphenols. Either proteins or polyphenols when present in the binding sites or surroundings promote a local change in the refractive index changing the properties of the gold nanodiscs, which can be measured by tracking the wavelength shift. Overall, the combination of a nanoplasmonic sensor and the imprinting material offers great chances to create tailored cavities with specific recognition properties, with long shelf life allowing at the same time monitor a specific biorecognition reaction in real-time and label-free. |
HIAS Gomes, FTC Moreira, MGF Sales Molecularly–imprinted materials acting as electroactive structure in potentiometric determination (Conference) Poster (P6), 5th Graduate Student Symposium on Molecular Imprinting, Queen´s University, Belfast, Reino Unido, 2013. @conference{Gomes2013, title = {Molecularly–imprinted materials acting as electroactive structure in potentiometric determination}, author = {HIAS Gomes and FTC Moreira and MGF Sales}, year = {2013}, date = {2013-08-15}, address = {Queen´s University, Belfast, Reino Unido}, organization = {Poster (P6), 5th Graduate Student Symposium on Molecular Imprinting, }, abstract = {A biomimetic sensor for screening a common drug in aquaculture environment is presented. The artificial host was obtained by non-covalent bulk imprinting approach of methacrylic acid (MAA), 2- vinyl pyridine (VP) or 2-acrylamido-2-methyl-1-propanesulfonic acid (AAMPSO) functional monomers, cross-linked by ethylene glycol dimethacrylic acid (EGDMA) or trimethylolpropane trimethacrylate (TRIM) within the template drug. The resulting polymers were ground and sieved to particle sizes ranging 50 to 150 μm. The template was then extracted from the particles by thorough washing with methanol/acetic acid and the efficiency of such extraction controlled by UV/Vis spectrophotometry. Finally, the particles were let dry at 60 0C until constant weight before use. The (re)binding ability of the several imprinted particles was evaluated by conventional steady-state assays followed by Scatchard analysis. Molecularly imprinted particles were further dispersed in 2-nitrophenyloctyl ether and entrapped in a poly(vinyl chloride) matrix for potentiometric detection. Nernstian slopes were observed and detection limits were down to ~450 ng/mL. Good selectivity of the selective membrane was observed towards coexisting drug contaminants in fish-food production by aquaculture activities. Finally, the sensors were successfully applied to monitor the target drug in fish samples, showing that the polymeric imprinted materials produced by bulk imprint may act as successful ionophores in potentiometric transduction.}, keywords = {}, pubstate = {published}, tppubtype = {conference} } A biomimetic sensor for screening a common drug in aquaculture environment is presented. The artificial host was obtained by non-covalent bulk imprinting approach of methacrylic acid (MAA), 2- vinyl pyridine (VP) or 2-acrylamido-2-methyl-1-propanesulfonic acid (AAMPSO) functional monomers, cross-linked by ethylene glycol dimethacrylic acid (EGDMA) or trimethylolpropane trimethacrylate (TRIM) within the template drug. The resulting polymers were ground and sieved to particle sizes ranging 50 to 150 μm. The template was then extracted from the particles by thorough washing with methanol/acetic acid and the efficiency of such extraction controlled by UV/Vis spectrophotometry. Finally, the particles were let dry at 60 0C until constant weight before use. The (re)binding ability of the several imprinted particles was evaluated by conventional steady-state assays followed by Scatchard analysis. Molecularly imprinted particles were further dispersed in 2-nitrophenyloctyl ether and entrapped in a poly(vinyl chloride) matrix for potentiometric detection. Nernstian slopes were observed and detection limits were down to ~450 ng/mL. Good selectivity of the selective membrane was observed towards coexisting drug contaminants in fish-food production by aquaculture activities. Finally, the sensors were successfully applied to monitor the target drug in fish samples, showing that the polymeric imprinted materials produced by bulk imprint may act as successful ionophores in potentiometric transduction. |
LAANA Truta, NS Ferreira, MGF Sales Host-tailored sensors for carnitine potentiometric measurements based on surface molecular imprinting (Conference) Poster (P10), 5th Graduate Student Symposium on Molecular Imprinting, Queen´s University, Belfast, Reino Unido, 2013. @conference{Truta2013b, title = {Host-tailored sensors for carnitine potentiometric measurements based on surface molecular imprinting}, author = {LAANA Truta and NS Ferreira and MGF Sales}, year = {2013}, date = {2013-08-15}, address = {Queen´s University, Belfast, Reino Unido}, organization = {Poster (P10), 5th Graduate Student Symposium on Molecular Imprinting, }, abstract = {A novel surface molecularly imprinted polymer (MIP) is presented for Carnitine (CRT), a potential biomarker of ovary cancer. It consists in a 3D polymeric network created on top of graphene layers and around the target template. The polymeric structure was obtained after radical polymerization of (vinylbenzyl)trimethylammonium chloride, 4-styrenesulfonic acid and vinyl pivalate, including in the reaction mixture ethylene glycol dimethacrylate as cross-linker and ammonium persulphate as initiator. Non-imprinted polymer (NIP) material was also produced, by excluding the template from the procedure. The imprinted material was further used for the selective determination of CRT by potentiometric transduction. A selective membrane was prepared for this purpose by using the MIP material as ionophore, and dispersing it in a plasticized poly(vinylchloride) matrix with a suitable charged lipophilic additive. All membranes were casted over a solid conductive support made of graphite and applied over the smaller end of an insulin syringe. The best membranes were also applied over conductive glass/plastic. Control membranes were also produced by replacing MIP by NIP material. The potentiometric performance of the above electrodes was evaluated against CRT solutions of increasing concentrations. Overall, the best devices displayed linear response with average slope and detection limit of 47.28 mV.decade-1 and 3.55x10-6 mol.L-1, respectively. The effect of pH upon the potentiometric response was evaluated for different buffer solutions (within 2-9) and the best performance for this sensor was obtained with HEPES (4-(2-hydroxyethyl)-1- piperazineethanesulfonic acid) buffer of pH 5.2. Good selectivity was observed against albumin, ascorbic acid, glucose, creatinine and urea, tested for concentrations up to their normal physiologic levels in urine. The application of the devices to the analysis of spiked samples showed recoveries ranging from 91% (± 6.8%) to 118% (± 11.2%), with relative errors below - 20%. Overall, the combination of the MIP sensory material with a suitable selective membrane and electrode design has lead to a promising tool for point-of-care applications, when applied to field monitoring of CRT in biological samples.}, keywords = {}, pubstate = {published}, tppubtype = {conference} } A novel surface molecularly imprinted polymer (MIP) is presented for Carnitine (CRT), a potential biomarker of ovary cancer. It consists in a 3D polymeric network created on top of graphene layers and around the target template. The polymeric structure was obtained after radical polymerization of (vinylbenzyl)trimethylammonium chloride, 4-styrenesulfonic acid and vinyl pivalate, including in the reaction mixture ethylene glycol dimethacrylate as cross-linker and ammonium persulphate as initiator. Non-imprinted polymer (NIP) material was also produced, by excluding the template from the procedure. The imprinted material was further used for the selective determination of CRT by potentiometric transduction. A selective membrane was prepared for this purpose by using the MIP material as ionophore, and dispersing it in a plasticized poly(vinylchloride) matrix with a suitable charged lipophilic additive. All membranes were casted over a solid conductive support made of graphite and applied over the smaller end of an insulin syringe. The best membranes were also applied over conductive glass/plastic. Control membranes were also produced by replacing MIP by NIP material. The potentiometric performance of the above electrodes was evaluated against CRT solutions of increasing concentrations. Overall, the best devices displayed linear response with average slope and detection limit of 47.28 mV.decade-1 and 3.55x10-6 mol.L-1, respectively. The effect of pH upon the potentiometric response was evaluated for different buffer solutions (within 2-9) and the best performance for this sensor was obtained with HEPES (4-(2-hydroxyethyl)-1- piperazineethanesulfonic acid) buffer of pH 5.2. Good selectivity was observed against albumin, ascorbic acid, glucose, creatinine and urea, tested for concentrations up to their normal physiologic levels in urine. The application of the devices to the analysis of spiked samples showed recoveries ranging from 91% (± 6.8%) to 118% (± 11.2%), with relative errors below - 20%. Overall, the combination of the MIP sensory material with a suitable selective membrane and electrode design has lead to a promising tool for point-of-care applications, when applied to field monitoring of CRT in biological samples. |
2012
SAA Almeida, MGF Sales, MCBSM Montenegro, E Arasa, M Puyol, J Alonso-Chamarro TCC microsystem based in moleculary imprinted polymer as ionophores for the potentiometric determination of Trimethoprim in aqualculture water (Conference) Poster (EC37), Euroanalysis 16, Chalenges in Modern Analytical Chemistry, Belgrade, Serbia, 2012. (BibTeX) @conference{Almeida2012b, title = {TCC microsystem based in moleculary imprinted polymer as ionophores for the potentiometric determination of Trimethoprim in aqualculture water }, author = {SAA Almeida and MGF Sales and MCBSM Montenegro and E Arasa and M Puyol and J Alonso-Chamarro }, year = {2012}, date = {2012-09-12}, address = {Belgrade, Serbia}, organization = {Poster (EC37), Euroanalysis 16, Chalenges in Modern Analytical Chemistry, }, keywords = {}, pubstate = {published}, tppubtype = {conference} } |
FTC Moreira, RAF Dutra, JPC Noronha, MGF Sales Surface imprinting approach on screen printed electrodes coated with carboxylated PVC for myoglobin detection with electrochemical transduction (Conference) Poster (P2258), Eurosensors XXVI, Krakow, Poland, 2012. @conference{Moreira2012b, title = {Surface imprinting approach on screen printed electrodes coated with carboxylated PVC for myoglobin detection with electrochemical transduction}, author = {FTC Moreira and RAF Dutra and JPC Noronha and MGF Sales}, year = {2012}, date = {2012-09-09}, address = {Krakow, Poland}, organization = {Poster (P2258), Eurosensors XXVI, }, abstract = {A novel surface molecularly-imprinted (MI) material to detect myoglobin (Myo) using gold screen printed electrodes (SPE) was developed. The sensitive detection was carry out by introducing a carboxylic polyvinyl chloride (PVC-COOH) layer on gold SPE surface. Myo was attached to the surface of gold SPE/PVC-COOH and the vacant spaces around it were filled by polymerizing acrylamide and N,N-methylenebisacrylamide (cross-linker). This polymerization was initiated by ammonium persulphate. After removing the template, the obtained material was able to rebind Myo and discriminate it among other interfering species. Various characterization techniques including electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) confirmed the surface modification. This sensor seemed a promising tool for screening Myo in point-of-care.}, keywords = {}, pubstate = {published}, tppubtype = {conference} } A novel surface molecularly-imprinted (MI) material to detect myoglobin (Myo) using gold screen printed electrodes (SPE) was developed. The sensitive detection was carry out by introducing a carboxylic polyvinyl chloride (PVC-COOH) layer on gold SPE surface. Myo was attached to the surface of gold SPE/PVC-COOH and the vacant spaces around it were filled by polymerizing acrylamide and N,N-methylenebisacrylamide (cross-linker). This polymerization was initiated by ammonium persulphate. After removing the template, the obtained material was able to rebind Myo and discriminate it among other interfering species. Various characterization techniques including electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) confirmed the surface modification. This sensor seemed a promising tool for screening Myo in point-of-care. |
RB Queiros, JPC Noronha, PVS Marques, MGF Sales Label-free detection of microcystin-LR in waters using real-time potentiometric biosensors based on single-walled carbon nanotubes imprinted polymers (Conference) Poster (P2258), Eurosensors XXVI, Krakow, Poland, 2012. (BibTeX) @conference{Queiros2012b, title = {Label-free detection of microcystin-LR in waters using real-time potentiometric biosensors based on single-walled carbon nanotubes imprinted polymers}, author = {RB Queiros and JPC Noronha and PVS Marques and MGF Sales}, year = {2012}, date = {2012-09-09}, address = {Krakow, Poland}, organization = {Poster (P2258), Eurosensors XXVI, }, keywords = {}, pubstate = {published}, tppubtype = {conference} } |
JRL Guerreiro, VAP Freitas, DS Sutherland, MGF Sales SPR based studies for pentagalloyl glucose binding to α-amylase (Conference) Poster (P2152), Eurosensors XXVI, Krakow, Poland, 2012. @conference{Guerreiro2012b, title = {SPR based studies for pentagalloyl glucose binding to α-amylase }, author = {JRL Guerreiro and VAP Freitas and DS Sutherland and MGF Sales}, year = {2012}, date = {2012-09-09}, address = {Krakow, Poland}, organization = {Poster (P2152), Eurosensors XXVI, }, abstract = {Summary Astringency is an organoleptic property that results from the interaction of salivary proteins with dietary polyphenols. It is of great importance to consumers and typically measured by sensorial panels; however it is subjective and expensive. The main goal of the present work is to develop an array of sensors to estimate astringency, through the evaluation of protein/polyphenol interactions. Preliminary assays were carried out by surface immobilization studies and consequent interaction with polyphenols measured by Surface Plasma Resonance (SPR). In order to get a specific binding between -amylase and pentagalloyl glucose (PGG), various surface chemistries were tested to minimize their ability to bind the surface. Carboxylic terminated thiol decreases the binding ability of PGG to the surface and allows covalent attachment of -amylase to the surface. Further studies included the analytical characterization and optimization of the Localized SPR sensor and application to wine samples, providing objectivity when compared to a trained panel. Motivation and results Polyphenols are the most frequent antioxidant compounds in human diet and their antioxidant properties have been associated to the prevention of degenerative diseases like cancer, cardiovascular as well as with other diseases related with oxidative stress. They also exert a great influence on organoleptic properties of food, in particular, colour and taste. Astringency is a result of the interaction between polyphenols and salivary proteins and the subsequent formation of insoluble aggregates. It is very important in terms of consumer preference, being measured by sensorial analysis with trained panels. This is however a time-consuming, expensive and subjective process. A cheap and easy tool to estimate astringency by mimicking protein/polyphenols interactions in the mouth would be highly appreciated. Thus, this work proposes a new sensor device where the protein is immobilized on a suitable surface and its interaction with polyphenols measured by Surface Plasma Resonance (SPR), an optical technique. a-amylase was the salivary protein selected for this purpose since it represents 30% of human salivary proteins. The selected polyphenol was pentagalloyl glucose (PGG), very common in wine aging in oak barrels and tea. To get specific binding between -amylase and PGG and prevent side-adsorption of PGG to the sensory surface, self-assembled monolayers on gold were tested with several alkanethiols bearing different terminating groups. Amine, carboxyl, methyl, alcohol and methyl polyethylene glycol groups were tested for this purpose. The adsorption of PGG 0.18 mol/L was smaller when carboxylic terminated thiol was used (Figure 1). Overall, these results indicated that using a surface with carboxyl terminated thiol leads to less secondary bindings meaning that the ability of PGG to bind the surface was reduced. Before -amylase immobilization on a SPR chip, the surface was activated with EDAC/NHS. The unreacted activated carboxylic groups were deactivated with different blocking agents and PGG adsorption was once again tested. The SPR results using Tris as a block agent showed that PGG was able to bind surface and it presented RU of 484±421. Further tests using LSPR to allow the construction of an array of sensors and their application to monitor the astringency of wine samples will follow this approach.}, keywords = {}, pubstate = {published}, tppubtype = {conference} } Summary Astringency is an organoleptic property that results from the interaction of salivary proteins with dietary polyphenols. It is of great importance to consumers and typically measured by sensorial panels; however it is subjective and expensive. The main goal of the present work is to develop an array of sensors to estimate astringency, through the evaluation of protein/polyphenol interactions. Preliminary assays were carried out by surface immobilization studies and consequent interaction with polyphenols measured by Surface Plasma Resonance (SPR). In order to get a specific binding between -amylase and pentagalloyl glucose (PGG), various surface chemistries were tested to minimize their ability to bind the surface. Carboxylic terminated thiol decreases the binding ability of PGG to the surface and allows covalent attachment of -amylase to the surface. Further studies included the analytical characterization and optimization of the Localized SPR sensor and application to wine samples, providing objectivity when compared to a trained panel. Motivation and results Polyphenols are the most frequent antioxidant compounds in human diet and their antioxidant properties have been associated to the prevention of degenerative diseases like cancer, cardiovascular as well as with other diseases related with oxidative stress. They also exert a great influence on organoleptic properties of food, in particular, colour and taste. Astringency is a result of the interaction between polyphenols and salivary proteins and the subsequent formation of insoluble aggregates. It is very important in terms of consumer preference, being measured by sensorial analysis with trained panels. This is however a time-consuming, expensive and subjective process. A cheap and easy tool to estimate astringency by mimicking protein/polyphenols interactions in the mouth would be highly appreciated. Thus, this work proposes a new sensor device where the protein is immobilized on a suitable surface and its interaction with polyphenols measured by Surface Plasma Resonance (SPR), an optical technique. a-amylase was the salivary protein selected for this purpose since it represents 30% of human salivary proteins. The selected polyphenol was pentagalloyl glucose (PGG), very common in wine aging in oak barrels and tea. To get specific binding between -amylase and PGG and prevent side-adsorption of PGG to the sensory surface, self-assembled monolayers on gold were tested with several alkanethiols bearing different terminating groups. Amine, carboxyl, methyl, alcohol and methyl polyethylene glycol groups were tested for this purpose. The adsorption of PGG 0.18 mol/L was smaller when carboxylic terminated thiol was used (Figure 1). Overall, these results indicated that using a surface with carboxyl terminated thiol leads to less secondary bindings meaning that the ability of PGG to bind the surface was reduced. Before -amylase immobilization on a SPR chip, the surface was activated with EDAC/NHS. The unreacted activated carboxylic groups were deactivated with different blocking agents and PGG adsorption was once again tested. The SPR results using Tris as a block agent showed that PGG was able to bind surface and it presented RU of 484±421. Further tests using LSPR to allow the construction of an array of sensors and their application to monitor the astringency of wine samples will follow this approach. |
G Cabral-Miranda, MGF Sales, RB Queirós, AM Monteiro, FJ Rios, SA Silva, EHG Yamashiro-Kanashiro, M Gidlund Development and characterization of an immunosensor for the determination of Oxidized Low Density Lipoprotein (ox-LDL) (Conference) Poster (P1523), 3rd European Congress of Immunology, Glasgow, Scotland, 2012. (BibTeX) @conference{Cabral-Miranda2012, title = {Development and characterization of an immunosensor for the determination of Oxidized Low Density Lipoprotein (ox-LDL)}, author = {G Cabral-Miranda and MGF Sales and RB Queirós and AM Monteiro and FJ Rios and SA Silva and EHG Yamashiro-Kanashiro and M Gidlund}, year = {2012}, date = {2012-09-05}, address = {Glasgow, Scotland}, organization = {Poster (P1523), 3rd European Congress of Immunology, }, keywords = {}, pubstate = {published}, tppubtype = {conference} } |
TSCR Rebelo, MGF Sales, JPC Noronha, J Costa-Rodrigues, MH Fernandes Oriented tailoring of plastic antibodies for prostate specific antigen and application of the imprinted material as ionophore in potentiometric detection (Conference) Poster (P119), Nanobio Europe, Varese, Italy, 2012. @conference{Rebelo2012, title = {Oriented tailoring of plastic antibodies for prostate specific antigen and application of the imprinted material as ionophore in potentiometric detection}, author = {TSCR Rebelo and MGF Sales and JPC Noronha and J Costa-Rodrigues and MH Fernandes}, year = {2012}, date = {2012-06-18}, address = {Varese, Italy}, organization = {Poster (P119), Nanobio Europe, }, abstract = {Prostate Specific Antigen (PSA) is the biomarker of choice for screening prostate cancer throughout the population, with PSA values above 10 ng/mL pointing out a high probability of associated cancer1. According to the most recent World Health Organization (WHO) data, prostate cancer is the commonest form of cancer in men in Europe2. Early detection of prostate cancer is thus very important and is currently made by screening PSA in men over 45 years old, combined with other alterations in serum and urine parameters. PSA is a glycoprotein with a molecular mass of approximately 32 kDa consisting of one polypeptide chain, which is produced by the secretory epithelium of human prostate. Currently, the standard methods available for PSA screening are immunoassays like Enzyme-Linked Immunoabsorbent Assay (ELISA). These methods are highly sensitive and specific for the detection of PSA, but they require expensive laboratory facilities and high qualify personal resources. Other highly sensitive and specific methods for the detection of PSA have also become available and are in its majority immunobiosensors1,3-5, relying on antibodies. Less expensive methods producing quicker responses are thus needed, which may be achieved by synthesizing artificial antibodies by means of molecular imprinting techniques. These should also be coupled to simple and low cost devices, such as those of the potentiometric kind, one approach that has been proven successful6. Potentiometric sensors offer the advantage of selectivity and portability for use in point-of-care and have been widely recognized as potential analytical tools in this field. The inherent method is simple, precise, accurate and inexpensive regarding reagent consumption and equipment involved. Thus, this work proposes a new plastic antibody for PSA, designed over the surface of graphene layers extracted from graphite. Charged monomers were used to enable an oriented tailoring of the PSA rebinding sites. Uncharged monomers were used as control. These materials were used as ionophores in conventional solid-contact graphite electrodes. The obtained results showed that the imprinted materials displayed a selective response to PSA. The electrodes with charged monomers showed a more stable and sensitive response, with an average slope of -44.2 mV/decade and a detection limit of 5.8X10-11 mol/L (2 ng/mL). The corresponding non-imprinted sensors showed smaller sensitivity, with average slopes of -24.8 mV/decade. The best sensors were successfully applied to the analysis of serum samples, with percentage recoveries of 106.5% and relatives errors of 6.5%.}, keywords = {}, pubstate = {published}, tppubtype = {conference} } Prostate Specific Antigen (PSA) is the biomarker of choice for screening prostate cancer throughout the population, with PSA values above 10 ng/mL pointing out a high probability of associated cancer1. According to the most recent World Health Organization (WHO) data, prostate cancer is the commonest form of cancer in men in Europe2. Early detection of prostate cancer is thus very important and is currently made by screening PSA in men over 45 years old, combined with other alterations in serum and urine parameters. PSA is a glycoprotein with a molecular mass of approximately 32 kDa consisting of one polypeptide chain, which is produced by the secretory epithelium of human prostate. Currently, the standard methods available for PSA screening are immunoassays like Enzyme-Linked Immunoabsorbent Assay (ELISA). These methods are highly sensitive and specific for the detection of PSA, but they require expensive laboratory facilities and high qualify personal resources. Other highly sensitive and specific methods for the detection of PSA have also become available and are in its majority immunobiosensors1,3-5, relying on antibodies. Less expensive methods producing quicker responses are thus needed, which may be achieved by synthesizing artificial antibodies by means of molecular imprinting techniques. These should also be coupled to simple and low cost devices, such as those of the potentiometric kind, one approach that has been proven successful6. Potentiometric sensors offer the advantage of selectivity and portability for use in point-of-care and have been widely recognized as potential analytical tools in this field. The inherent method is simple, precise, accurate and inexpensive regarding reagent consumption and equipment involved. Thus, this work proposes a new plastic antibody for PSA, designed over the surface of graphene layers extracted from graphite. Charged monomers were used to enable an oriented tailoring of the PSA rebinding sites. Uncharged monomers were used as control. These materials were used as ionophores in conventional solid-contact graphite electrodes. The obtained results showed that the imprinted materials displayed a selective response to PSA. The electrodes with charged monomers showed a more stable and sensitive response, with an average slope of -44.2 mV/decade and a detection limit of 5.8X10-11 mol/L (2 ng/mL). The corresponding non-imprinted sensors showed smaller sensitivity, with average slopes of -24.8 mV/decade. The best sensors were successfully applied to the analysis of serum samples, with percentage recoveries of 106.5% and relatives errors of 6.5%. |
2011
SAA Almeida, MGF Sales, MCBSM Montenegro, E Arasa, M Puyol, J Alonso-Chamarro Micro-potentiometric flow system of low temperature co-fired ceramics for sulfamethoxazole determination in aquaculture water (Conference) Poster (P29), International Conference on Occupational and Environmental Health, Porto, Portugal, 2011. (BibTeX) @conference{Almeida2011b, title = {Micro-potentiometric flow system of low temperature co-fired ceramics for sulfamethoxazole determination in aquaculture water}, author = {SAA Almeida and MGF Sales and MCBSM Montenegro and E Arasa and M Puyol and J Alonso-Chamarro}, year = {2011}, date = {2011-10-17}, address = {Porto, Portugal}, organization = {Poster (P29), International Conference on Occupational and Environmental Health, }, keywords = {}, pubstate = {published}, tppubtype = {conference} } |
FTC Moreira, RAF Dutra, JPC Noronha, MGF Sales Artificial antibodies for troponin T by its imprinting on the surface of multiwalled carbon nanotubes: its use as sensory surfaces (Conference) Poster (P128), apresentado na 2nd International Conference on Bio-Sensing Technology, Amsterdam, Netherlands, 2011. @conference{Moreira2011b, title = {Artificial antibodies for troponin T by its imprinting on the surface of multiwalled carbon nanotubes: its use as sensory surfaces}, author = {FTC Moreira and RAF Dutra and JPC Noronha and MGF Sales }, year = {2011}, date = {2011-10-12}, address = {Amsterdam, Netherlands}, organization = {Poster (P128), apresentado na 2nd International Conference on Bio-Sensing Technology, }, abstract = {A novel molecular imprinting sensor for the potentiometric transduction of troponin T (TnT) was synthesized on the surface of multiwalled carbon nanotubes. Troponin T was used as the template molecule, acrylamide as the functional monomer, N,N′-methylenebisacrylamide as the cross-linker and ammonium persulphate as the initiator (figure 1). The imprinted was used as electroactive material on poly(vinyl chloride) PVC/TnT selective membranes. These were prepared by dispersing it on plasticizer, namely o-nitrophenyl octylether. A coated-wire (silver, titanium, gold and nickel) ion-selective electrode has been constructed using (PVC/TnT) selective membranes. Sensor of PVC/TnT showed best analytical features with a coated –wire gold in HEPES buffer at pH 7, with limits of detection of 0.157 μg ml-1 and anionic slope -49.6 mV decade -1 (figure3). The NI particles showed no ability for recognition of the analyte. Good selectivity was observed towards creatinine, sacarose, fructose, myoglobin, sodium glutamate, thiamine and urea.}, keywords = {}, pubstate = {published}, tppubtype = {conference} } A novel molecular imprinting sensor for the potentiometric transduction of troponin T (TnT) was synthesized on the surface of multiwalled carbon nanotubes. Troponin T was used as the template molecule, acrylamide as the functional monomer, N,N′-methylenebisacrylamide as the cross-linker and ammonium persulphate as the initiator (figure 1). The imprinted was used as electroactive material on poly(vinyl chloride) PVC/TnT selective membranes. These were prepared by dispersing it on plasticizer, namely o-nitrophenyl octylether. A coated-wire (silver, titanium, gold and nickel) ion-selective electrode has been constructed using (PVC/TnT) selective membranes. Sensor of PVC/TnT showed best analytical features with a coated –wire gold in HEPES buffer at pH 7, with limits of detection of 0.157 μg ml-1 and anionic slope -49.6 mV decade -1 (figure3). The NI particles showed no ability for recognition of the analyte. Good selectivity was observed towards creatinine, sacarose, fructose, myoglobin, sodium glutamate, thiamine and urea. |
JRL Guerreiro, VAP Freitas, DS Sutherland, MGF Sales Protein/polyphenol interaction study by an optical sensor (Conference) Poster (P96), apresentado na 2nd International Conference on Bio-Sensing Technology, Amsterdam, Netherlands, 2011. @conference{Guerreiro2011b, title = {Protein/polyphenol interaction study by an optical sensor}, author = {JRL Guerreiro and VAP Freitas and DS Sutherland and MGF Sales}, year = {2011}, date = {2011-10-10}, address = {Amsterdam, Netherlands}, organization = {Poster (P96), apresentado na 2nd International Conference on Bio-Sensing Technology, }, abstract = {Polyphenols are present in a wide range of beverages and foodstuffs obtained from natural products. They play an important role on health, inducing antimutagenic activity and preventing carcinogenic and cardiovascular diseases1. However, they are also the main responsible by the drying and puckering sensations known by astringency, when they interact with salivary proteins and decrease mouth lubrication. This interaction may also lead to the inhibition of digestive enzymes as well as some antinutritional functions. Knowing polyphenol/protein interaction is fundamental to understand their role in many biological effects and food organoleptic properties2. However, these studies are not an easy task. Most methods addressing this interaction are based on the formation of insoluble aggregates between polyphenols and proteins and ignore all soluble products coming from this interaction that could also affect astringency or other relevant biological effects. Thus, a new method is presented relying on surface studies that transduce all interactions by an optical sensor, regardless of their solubility. The basis of the developed sensor is the surface immobilization of BSA that in the presence of polyphenols and ferric ion develops a purple color. Silica beads were used as the physical support of the protein and tannic acid was tested as polyphenol. Surface immobilization of the protein was conducted by introducing an amine layer on the surface of the beads. This amine group reacted with glutaraldehyde, leading the readily available aldehyde functions that reacted later with BSA. The result was a protein linked by a covalent bond to the modified silica beads. Two different methodologies were used for this purpose and compared. Each of these relied on different reaction times, temperature, concentration, pH and reactant nature. The optimized conditions were used to calibrate the sensor. The calibration curve plot colour unit in function of log (tannic acid, M) and the correspondent parameters were 27,6 colour units decade-1 for slope and a the correlation coefficient of 0,9545. As may be seen in Figure 1, the color changed from light to dark purple as the concentration of tannic acid increased.}, keywords = {}, pubstate = {published}, tppubtype = {conference} } Polyphenols are present in a wide range of beverages and foodstuffs obtained from natural products. They play an important role on health, inducing antimutagenic activity and preventing carcinogenic and cardiovascular diseases1. However, they are also the main responsible by the drying and puckering sensations known by astringency, when they interact with salivary proteins and decrease mouth lubrication. This interaction may also lead to the inhibition of digestive enzymes as well as some antinutritional functions. Knowing polyphenol/protein interaction is fundamental to understand their role in many biological effects and food organoleptic properties2. However, these studies are not an easy task. Most methods addressing this interaction are based on the formation of insoluble aggregates between polyphenols and proteins and ignore all soluble products coming from this interaction that could also affect astringency or other relevant biological effects. Thus, a new method is presented relying on surface studies that transduce all interactions by an optical sensor, regardless of their solubility. The basis of the developed sensor is the surface immobilization of BSA that in the presence of polyphenols and ferric ion develops a purple color. Silica beads were used as the physical support of the protein and tannic acid was tested as polyphenol. Surface immobilization of the protein was conducted by introducing an amine layer on the surface of the beads. This amine group reacted with glutaraldehyde, leading the readily available aldehyde functions that reacted later with BSA. The result was a protein linked by a covalent bond to the modified silica beads. Two different methodologies were used for this purpose and compared. Each of these relied on different reaction times, temperature, concentration, pH and reactant nature. The optimized conditions were used to calibrate the sensor. The calibration curve plot colour unit in function of log (tannic acid, M) and the correspondent parameters were 27,6 colour units decade-1 for slope and a the correlation coefficient of 0,9545. As may be seen in Figure 1, the color changed from light to dark purple as the concentration of tannic acid increased. |
RB Queirós, PVS Marques, JPC Noronha, N de-los-Santos-Álvarez, AJ Miranda-Ordieres, MGF Sales Analytical performance of a DNA aptamer-based for E. coli detection in water (Conference) Poster (P126), apresentado na 2nd International Conference on Bio-Sensing Technology, Amsterdam, Netherlands, 2011. (BibTeX) @conference{Queirós2011b, title = {Analytical performance of a DNA aptamer-based for E. coli detection in water}, author = {RB Queirós and PVS Marques and JPC Noronha and N de-los-Santos-Álvarez and AJ Miranda-Ordieres and MGF Sales}, year = {2011}, date = {2011-10-10}, address = {Amsterdam, Netherlands}, organization = {Poster (P126), apresentado na 2nd International Conference on Bio-Sensing Technology, }, keywords = {}, pubstate = {published}, tppubtype = {conference} } |
LAANA Truta, S Tarelho, AL Castro, MGF Sales, HM Teixeira Development and validation of an analytical methodology by GC/MS/MS for antidepressants detection in whole blood (Conference) Poster (P16), 19th IAFS World Meeting, 9th WPMO Triennial Meeting, 5th MAFS Meeting, Funchal, Madeira, Portugal, 2011. (BibTeX) @conference{Truta2011, title = {Development and validation of an analytical methodology by GC/MS/MS for antidepressants detection in whole blood}, author = {LAANA Truta and S Tarelho and AL Castro and MGF Sales and HM Teixeira}, year = {2011}, date = {2011-09-14}, address = {Funchal, Madeira, Portugal}, organization = {Poster (P16), 19th IAFS World Meeting, 9th WPMO Triennial Meeting, 5th MAFS Meeting, }, keywords = {}, pubstate = {published}, tppubtype = {conference} } |
FTC Moreira, Z Tehrani, RAF Dutra, JPC Noronha, OJ Guy, MGF Sales Electrochemical assay for ischemic episodes diagnosis (Conference) Poster, European Biomarkers Summit, London, United Kingdom, 2011. @conference{Moreira2011b, title = {Electrochemical assay for ischemic episodes diagnosis}, author = {FTC Moreira and Z Tehrani and RAF Dutra and JPC Noronha and OJ Guy and MGF Sales}, year = {2011}, date = {2011-05-18}, address = {London, United Kingdom}, organization = {Poster, European Biomarkers Summit, }, abstract = {Cardiovascular diseases are the leading cause of death around the world. Since the treatment for each condition differs, it is important that physicians have a way to quickly and easily diagnose it. Monitoring cardiac biomarker is a useful diagnostic tool [1], done by taking a blood sample when a patient has symptoms of ACS. There are four important cardiac markers: Myoglobin (Mb), creatinine kinase-MB, troponin I, and troponin T [2]. Although not cardiac-specific, Mb is one of the very early known markers that increase after acute myocardial infarction [3], and its rapid screening under acute physiological conditions is fundamental. This is typically carried out by means of immunochemical assays that are very selective but of small stability and of high price. An electrochemical immunoassay for myoglobin with silicon as a subtract may fulfill this propose. The backside contact, silicon-based transducers with vacuum-deposited gold layer were evaluated as the base for electrochemical biosensors construction. The silicon surface were electrochemical modified with diazonium and the cardiac antibody were attach to a aminated CHIP surface. The fluorescent quantum dot were attach to antibody to ensure covalent attachment of the antibody to the CHIP. The attachment were verify by confocal scanning microscopy.}, keywords = {}, pubstate = {published}, tppubtype = {conference} } Cardiovascular diseases are the leading cause of death around the world. Since the treatment for each condition differs, it is important that physicians have a way to quickly and easily diagnose it. Monitoring cardiac biomarker is a useful diagnostic tool [1], done by taking a blood sample when a patient has symptoms of ACS. There are four important cardiac markers: Myoglobin (Mb), creatinine kinase-MB, troponin I, and troponin T [2]. Although not cardiac-specific, Mb is one of the very early known markers that increase after acute myocardial infarction [3], and its rapid screening under acute physiological conditions is fundamental. This is typically carried out by means of immunochemical assays that are very selective but of small stability and of high price. An electrochemical immunoassay for myoglobin with silicon as a subtract may fulfill this propose. The backside contact, silicon-based transducers with vacuum-deposited gold layer were evaluated as the base for electrochemical biosensors construction. The silicon surface were electrochemical modified with diazonium and the cardiac antibody were attach to a aminated CHIP surface. The fluorescent quantum dot were attach to antibody to ensure covalent attachment of the antibody to the CHIP. The attachment were verify by confocal scanning microscopy. |
TESES DE DOUTORAMENTO
2020
2019
ANA PATRÍCIA TAVARES MOREIRA University of Minho, 2019, (grau de Doutor em Engenharia Biomédica ). @phdthesis{Moreira2019, title = {Desenvolvimento de um biossensor integrado em células solares sensibilizadas por corante para medir biomarcadores de cancro/ Development of biosensor integrated into Dye Sensitized Solar Cells for measuring cancer biomarkers}, author = {ANA PATRÍCIA TAVARES MOREIRA }, editor = {MGF Sales, G Minas }, year = {2019}, date = {2019-12-13}, school = {University of Minho}, abstract = {RESUMO Os biomarcadores são biomoléculas presentes em tecidos ou fluidos corporais e desempenham um papel importante como ferramenta de diagnóstico em laboratórios clínicos e em hospitais, especialmente na área de oncologia. Estas biomoléculas podem ser associadas a doenças cancerígenas, possibilitam o diagnóstico e prognóstico destas doenças, bem como o acompanhamento e a sua evolução, face a um determinado tratamento. A determinação desses biomarcadores deve ser, por isso, de baixo custo e rápida, com recurso a instrumentos pequenos e portáteis, de forma a permitir a sua utilização em programas de rastreio e em contexto clínico. Neste contexto, os biossensores representam um papel essencial, por serem tipicamente rápidos e baratos e permitirem um diagnóstico no ponto de cuidado médico. Apesar de existirem descritos na literatura vários biossensores dirigidos a biomarcadores de cancro, falta ainda um biossensor que apresente baixo custo e uma produção simples, com um reduzido número de requisitos. Estas características são fundamentais para a sua aplicação no rastreio do cancro. Este trabalho propõe, por isso, a utilização de um material biomimético como elemento de bioreconhecimento para deteção de biomarcadores do cancro, material esse que atua como um anticorpo natural. Este material é sintético, barato e pode ser produzido para eventualmente qualquer molécula alvo, através de uma impressão molecular em estruturas poliméricas, com subsequente produção de polímeros molecularmente impressos (MIPs, do inglês Molecularly-Imprinted Polymers). A técnica eletroquímica é utilizada durante o desenvolvimento e a caracterização do MIP, por permitir procedimentos rápidos e de baixo custo, bem como a sua produção em suportes adequados do ponto de vista ambiental. O biossensor desenvolvido neste trabalho foi integrado, ainda, numa célula fotovoltaica, tendo em vista a produção de um novo sistema híbrido: um sistema elétrico que não necessite de uma fonte de energia elétrica. Essa célula fotovoltaica, uma célula solar sensibilizada por corante (DSSC, do inglês, Dye Sensitized Solar Cell), caracteriza-se pelo facto da energia gerada pelo sistema híbrido ser dependente da concentração de um biomarcador do cancro. Além disso, este sistema evoluiu no sentido de fornecer um sinal visível a qualquer utilizador, utilizando a sua interface com uma célula electrocrómica. Esta célula usou como material electrocrómico o poli(3,4-etilenodioxitiofeno) e um seu derivado, recebendo a energia gerada pelo dispositivo híbrido e convertendo-a numa dada cor. A intensidade desta cor é, também, dependente da concentração do biomarcador. Em geral, este trabalho descreve a combinação altamente inovadora de diferentes técnicas (materiais sensores, células fotovoltaicas e electrocrómicas) para a produção de uma nova geração de dispositivos, dirigidos à deteção de biomarcadores do cancro. Esta combinação permitiu desenvolver sistemas simples e sem requisitos específicos, tornando-se apenas necessária a presença da amostra para gerar informação analítica. ABSTRACT Biomarkers are biomolecules present in tissues or body fluids that may be associated with cancer diseases. These biomolecules have shown an important role as diagnostic tools in clinical laboratories and hospitals, especially in oncology. Biomarkers may allow assessing cancer in an initial state of the disease, establishing an accurate prognosis, and following-up the progression of disease along the patient treatment. The determination of these biomarkers should therefore be of low cost, also offering a fast response, with small and portable instruments, so that this may be of use in screening programs and point-of-care context. In this context, biosensors represent an essential role, due to their advantages as fast and cost-effective method in clinical diagnosis. Although there are several biosensors for determining cancer biomarkers reported in the literature, a biosensor that offers low cost and simple production features, with little requirements is still missing. These shall be very important in future wide screening programs in early cancer detection. Thus, this work makes use of a biomimetic material as a biorecognition element for the detection of cancer biomarkers, acting like a natural antibody. This antibody-like material is synthetic, low cost and tailored on demand by molecularly-imprinted polymer (MIP) technology. Herein, electrochemical-based approaches were employed in its production, yielding a quick and low-cost procedure, as well as low cost supports. The biosensor developed herein is further integrated in a photovoltaic cell to generate a new hybrid sensing device that is self-powered. The photovoltaic cell was a dye sensitized solar cell (DSSC) and the electrical energy produced by the hybrid device depended on the concentration of cancer biomarker present. Moreover, this device also evolved to a self-signalling device, by coupling it to an electrochromic cell. This electrochromic cell consisted of a poly(3,4-ethylenedioxythiophene)-based electrochromic material and received the electrical energy generated by the hybrid system, converting it into a given colour. In this, the colour intensity was also concentration dependent. Overall, this work describes the highly innovative combination of sensing material, and photovoltaic and electrochromic cells, to produce a new generation of self-powered and self-signalled devices devoted to cancer biomarker detection. This combination has zero-requirements, and only the sample shall be required to retrieve analytical data. }, note = {grau de Doutor em Engenharia Biomédica }, keywords = {}, pubstate = {published}, tppubtype = {phdthesis} } RESUMO Os biomarcadores são biomoléculas presentes em tecidos ou fluidos corporais e desempenham um papel importante como ferramenta de diagnóstico em laboratórios clínicos e em hospitais, especialmente na área de oncologia. Estas biomoléculas podem ser associadas a doenças cancerígenas, possibilitam o diagnóstico e prognóstico destas doenças, bem como o acompanhamento e a sua evolução, face a um determinado tratamento. A determinação desses biomarcadores deve ser, por isso, de baixo custo e rápida, com recurso a instrumentos pequenos e portáteis, de forma a permitir a sua utilização em programas de rastreio e em contexto clínico. Neste contexto, os biossensores representam um papel essencial, por serem tipicamente rápidos e baratos e permitirem um diagnóstico no ponto de cuidado médico. Apesar de existirem descritos na literatura vários biossensores dirigidos a biomarcadores de cancro, falta ainda um biossensor que apresente baixo custo e uma produção simples, com um reduzido número de requisitos. Estas características são fundamentais para a sua aplicação no rastreio do cancro. Este trabalho propõe, por isso, a utilização de um material biomimético como elemento de bioreconhecimento para deteção de biomarcadores do cancro, material esse que atua como um anticorpo natural. Este material é sintético, barato e pode ser produzido para eventualmente qualquer molécula alvo, através de uma impressão molecular em estruturas poliméricas, com subsequente produção de polímeros molecularmente impressos (MIPs, do inglês Molecularly-Imprinted Polymers). A técnica eletroquímica é utilizada durante o desenvolvimento e a caracterização do MIP, por permitir procedimentos rápidos e de baixo custo, bem como a sua produção em suportes adequados do ponto de vista ambiental. O biossensor desenvolvido neste trabalho foi integrado, ainda, numa célula fotovoltaica, tendo em vista a produção de um novo sistema híbrido: um sistema elétrico que não necessite de uma fonte de energia elétrica. Essa célula fotovoltaica, uma célula solar sensibilizada por corante (DSSC, do inglês, Dye Sensitized Solar Cell), caracteriza-se pelo facto da energia gerada pelo sistema híbrido ser dependente da concentração de um biomarcador do cancro. Além disso, este sistema evoluiu no sentido de fornecer um sinal visível a qualquer utilizador, utilizando a sua interface com uma célula electrocrómica. Esta célula usou como material electrocrómico o poli(3,4-etilenodioxitiofeno) e um seu derivado, recebendo a energia gerada pelo dispositivo híbrido e convertendo-a numa dada cor. A intensidade desta cor é, também, dependente da concentração do biomarcador. Em geral, este trabalho descreve a combinação altamente inovadora de diferentes técnicas (materiais sensores, células fotovoltaicas e electrocrómicas) para a produção de uma nova geração de dispositivos, dirigidos à deteção de biomarcadores do cancro. Esta combinação permitiu desenvolver sistemas simples e sem requisitos específicos, tornando-se apenas necessária a presença da amostra para gerar informação analítica. ABSTRACT Biomarkers are biomolecules present in tissues or body fluids that may be associated with cancer diseases. These biomolecules have shown an important role as diagnostic tools in clinical laboratories and hospitals, especially in oncology. Biomarkers may allow assessing cancer in an initial state of the disease, establishing an accurate prognosis, and following-up the progression of disease along the patient treatment. The determination of these biomarkers should therefore be of low cost, also offering a fast response, with small and portable instruments, so that this may be of use in screening programs and point-of-care context. In this context, biosensors represent an essential role, due to their advantages as fast and cost-effective method in clinical diagnosis. Although there are several biosensors for determining cancer biomarkers reported in the literature, a biosensor that offers low cost and simple production features, with little requirements is still missing. These shall be very important in future wide screening programs in early cancer detection. Thus, this work makes use of a biomimetic material as a biorecognition element for the detection of cancer biomarkers, acting like a natural antibody. This antibody-like material is synthetic, low cost and tailored on demand by molecularly-imprinted polymer (MIP) technology. Herein, electrochemical-based approaches were employed in its production, yielding a quick and low-cost procedure, as well as low cost supports. The biosensor developed herein is further integrated in a photovoltaic cell to generate a new hybrid sensing device that is self-powered. The photovoltaic cell was a dye sensitized solar cell (DSSC) and the electrical energy produced by the hybrid device depended on the concentration of cancer biomarker present. Moreover, this device also evolved to a self-signalling device, by coupling it to an electrochromic cell. This electrochromic cell consisted of a poly(3,4-ethylenedioxythiophene)-based electrochromic material and received the electrical energy generated by the hybrid system, converting it into a given colour. In this, the colour intensity was also concentration dependent. Overall, this work describes the highly innovative combination of sensing material, and photovoltaic and electrochromic cells, to produce a new generation of self-powered and self-signalled devices devoted to cancer biomarker detection. This combination has zero-requirements, and only the sample shall be required to retrieve analytical data. |
LILIANA ADELINA AFONSO NOVO DE ALMEIDA TRUTA Merging biosensors and photovoltaic cells for cancer biomarker detection (PhD Thesis) University of Aveiro, 2019, (grau de Doutor em Nanociências e Nanotecnologia ). @phdthesis{Truta2019b, title = {Merging biosensors and photovoltaic cells for cancer biomarker detection}, author = {LILIANA ADELINA AFONSO NOVO DE ALMEIDA TRUTA}, editor = {MGF Sales e T Trindade}, year = {2019}, date = {2019-02-26}, school = {University of Aveiro}, abstract = {Cancer diseases are exponentially growing in Portugal throughout the years, reflecting the same scenario as in Europe. Several efforts have been made to minimize cancer incidence, including adopting a healthier behaviour (as vaccination programs and lifestyle adjustments) and early diagnosis of the disease. Currently, the screening of the disease can be performed by monitoring tumour markers (CEA, CA15-3, CA125, CA19-9, PSA, among others) that circulate in the body fluids, as blood and urine. Thus, the development of new analytical tools for detecting these biomarkers in a clinical context is also of growing interest. This PhD thesis aimed to develop low-cost sensing platforms based on newly biomaterials to screen cancer biomarkers in biological samples towards on-site application. For the purpose, different analyte targets were presented herein, including CRT, which is a potential biomarker in ovarian cancer, and CEA, a tumor marker that despite being an indicator of other types of cancer such as breast, pancreas and lung, offers high specificity in colorectal cancer. Distinct approaches were developed for this purpose, based on the design of plastic antibodies by means of molecular imprinting technology, and on antibody-antigen recognition though the development of immunosensors for the detection of colorectal cancer biomarker. The sensing platforms built on a solid conductive glass support (composed by fluorine-doped tin oxide film (FTO)) allowed understanding the interaction between cancer biomarker and the sensing material through electrical signals. In order to allow the portability of these devices, a new approach was proposed in this project, establishing the integration of a sensing platform in a photovoltaic cell, namely in a DSSC, once these cells are capable of generating electrical energy from solar energy. In addition, efforts were made to improve the overall performance of these photovoltaic cells, modifying the DSSCs configuration by introducing metallic nanoparticles, such as gold nanoparticles, in the composition of photoanodes, or even, by the chemical functionalization of the semiconductor material, followed by the metallic nanoparticles binding. In general, the emerging biosensing materials and platforms out coming from this project may contribute for the development of new non-invasive or minimally invasive and self-sustained devices suitable for the early diagnosis of cancer biomarkers in a clinical application. O cancro é uma doença que tem vindo aumentar de forma exponencial em Portugal ao longo dos anos, à semelhança do que acontece no resto da Europa. Deste modo, diversos esforços têm vindo a ser feitos no sentido de mitigar a sua incidência, entre os quais a adesão a comportamentos saudáveis (programas de vacinação e modificação do estilo de vida) e ao diagnóstico precoce da doença. Atualmente, o rastreio da doença é concretizado através de marcadores tumorais (CEA, CA15-3, CA125, CA19-9, PSA, entres outros), não-invasivos, que circulam no organismo, em fluídos como sangue e urina. Neste sentido, esta tese de doutoramento teve o intuito de desenvolver plataformas sensoras de baixo custo, baseadas em novos biomateriais sensores que facultem o rastreio dos biomarcadores do cancro em amostras biológicas, de forma a serem aplicados num contexto clínico. Para este efeito foram consideradas como moléculas alvo a carnitina (CRT), um potencial biomarcador para o diagnóstico do cancro do ovário, e o antigénio carcinoembrionário (CEA), um marcador tumoral que, apesar de ser indicador de outros tipos de cancro como da mama, do pâncreas e do pulmão, apresenta uma elevada especificidade para o cancro do colorretal. Para a conceção destes biossensores foram concretizadas duas abordagens distintas que se basearam no desenvolvimento de anticorpos plásticos, recorrendo à síntese de polímeros de impressão molecular, e no reconhecimento anticorpo-antigénio, através da construção de imunossensores para a deteção do biomarcador do cancro do colorretal. As plataformas sensoras construídas sobre um suporte sólido de vidro condutor (composto por um filme de óxido de estanho dopado com flúor) permitiram avaliar a interação entre o biomarcador e o material sensor através de sinais de natureza elétrica. De modo a possibilitar a portabilidade destes dipositivos para a deteção de marcadores tumorais, neste projeto foi proposta uma nova abordagem que estabeleceu a integração de uma plataforma sensora numa célula fotovoltaica, nomeadamente, numa célula solar sensibilizada por corante (Dye-Sensitized Solar Cell, DSSC), uma vez que estas são, por si só, células capazes de gerar energia eléctrica por conversão da energia solar. Também foram realizados esforços no sentido de melhorar o desempenho geral destas células fotovoltaicas, alterando a sua configuração, através da implementação de nanopartículas metálicas, como as nanopartículas de ouro, na constituição do fotoânodo, ou até mesmo através da funcionalização química do material semicondutor que compõe estes fotoânodos e, posterior, ligação a estas nanopartículas metálicas. De uma forma geral, os dispositivos sensores desenvolvidos poderão ser uma ferramenta promissora, de baixo custo e portátil, para um diagnóstico precoce, ou para o acompanhamento e a monitorização terapêutica do cancro, de modo não invasivo ou minimamente invasivo, para aplicação num contexto clínico}, note = {grau de Doutor em Nanociências e Nanotecnologia }, keywords = {}, pubstate = {published}, tppubtype = {phdthesis} } Cancer diseases are exponentially growing in Portugal throughout the years, reflecting the same scenario as in Europe. Several efforts have been made to minimize cancer incidence, including adopting a healthier behaviour (as vaccination programs and lifestyle adjustments) and early diagnosis of the disease. Currently, the screening of the disease can be performed by monitoring tumour markers (CEA, CA15-3, CA125, CA19-9, PSA, among others) that circulate in the body fluids, as blood and urine. Thus, the development of new analytical tools for detecting these biomarkers in a clinical context is also of growing interest. This PhD thesis aimed to develop low-cost sensing platforms based on newly biomaterials to screen cancer biomarkers in biological samples towards on-site application. For the purpose, different analyte targets were presented herein, including CRT, which is a potential biomarker in ovarian cancer, and CEA, a tumor marker that despite being an indicator of other types of cancer such as breast, pancreas and lung, offers high specificity in colorectal cancer. Distinct approaches were developed for this purpose, based on the design of plastic antibodies by means of molecular imprinting technology, and on antibody-antigen recognition though the development of immunosensors for the detection of colorectal cancer biomarker. The sensing platforms built on a solid conductive glass support (composed by fluorine-doped tin oxide film (FTO)) allowed understanding the interaction between cancer biomarker and the sensing material through electrical signals. In order to allow the portability of these devices, a new approach was proposed in this project, establishing the integration of a sensing platform in a photovoltaic cell, namely in a DSSC, once these cells are capable of generating electrical energy from solar energy. In addition, efforts were made to improve the overall performance of these photovoltaic cells, modifying the DSSCs configuration by introducing metallic nanoparticles, such as gold nanoparticles, in the composition of photoanodes, or even, by the chemical functionalization of the semiconductor material, followed by the metallic nanoparticles binding. In general, the emerging biosensing materials and platforms out coming from this project may contribute for the development of new non-invasive or minimally invasive and self-sustained devices suitable for the early diagnosis of cancer biomarkers in a clinical application. O cancro é uma doença que tem vindo aumentar de forma exponencial em Portugal ao longo dos anos, à semelhança do que acontece no resto da Europa. Deste modo, diversos esforços têm vindo a ser feitos no sentido de mitigar a sua incidência, entre os quais a adesão a comportamentos saudáveis (programas de vacinação e modificação do estilo de vida) e ao diagnóstico precoce da doença. Atualmente, o rastreio da doença é concretizado através de marcadores tumorais (CEA, CA15-3, CA125, CA19-9, PSA, entres outros), não-invasivos, que circulam no organismo, em fluídos como sangue e urina. Neste sentido, esta tese de doutoramento teve o intuito de desenvolver plataformas sensoras de baixo custo, baseadas em novos biomateriais sensores que facultem o rastreio dos biomarcadores do cancro em amostras biológicas, de forma a serem aplicados num contexto clínico. Para este efeito foram consideradas como moléculas alvo a carnitina (CRT), um potencial biomarcador para o diagnóstico do cancro do ovário, e o antigénio carcinoembrionário (CEA), um marcador tumoral que, apesar de ser indicador de outros tipos de cancro como da mama, do pâncreas e do pulmão, apresenta uma elevada especificidade para o cancro do colorretal. Para a conceção destes biossensores foram concretizadas duas abordagens distintas que se basearam no desenvolvimento de anticorpos plásticos, recorrendo à síntese de polímeros de impressão molecular, e no reconhecimento anticorpo-antigénio, através da construção de imunossensores para a deteção do biomarcador do cancro do colorretal. As plataformas sensoras construídas sobre um suporte sólido de vidro condutor (composto por um filme de óxido de estanho dopado com flúor) permitiram avaliar a interação entre o biomarcador e o material sensor através de sinais de natureza elétrica. De modo a possibilitar a portabilidade destes dipositivos para a deteção de marcadores tumorais, neste projeto foi proposta uma nova abordagem que estabeleceu a integração de uma plataforma sensora numa célula fotovoltaica, nomeadamente, numa célula solar sensibilizada por corante (Dye-Sensitized Solar Cell, DSSC), uma vez que estas são, por si só, células capazes de gerar energia eléctrica por conversão da energia solar. Também foram realizados esforços no sentido de melhorar o desempenho geral destas células fotovoltaicas, alterando a sua configuração, através da implementação de nanopartículas metálicas, como as nanopartículas de ouro, na constituição do fotoânodo, ou até mesmo através da funcionalização química do material semicondutor que compõe estes fotoânodos e, posterior, ligação a estas nanopartículas metálicas. De uma forma geral, os dispositivos sensores desenvolvidos poderão ser uma ferramenta promissora, de baixo custo e portátil, para um diagnóstico precoce, ou para o acompanhamento e a monitorização terapêutica do cancro, de modo não invasivo ou minimamente invasivo, para aplicação num contexto clínico |
2018
GABRIELA FERREIRA DE VASCONCELOS MARTINS New devices to monitor oxidative stress biomarkers in point-of-care: a new tool for cancer prevention (PhD Thesis) Universidade Nova de Lisboa, 2018, (grau de Doutor em Nanotecnologias e Nanociências ). @phdthesis{Martins2019, title = {New devices to monitor oxidative stress biomarkers in point-of-care: a new tool for cancer prevention }, author = {GABRIELA FERREIRA DE VASCONCELOS MARTINS}, editor = {MGF Sales, Elvira Fortunato }, year = {2018}, date = {2018-12-18}, school = {Universidade Nova de Lisboa}, abstract = {Segundo as recentes estatísticas da Organização Mundial de Saúde (OMS), a segunda principal causa de morte a nível mundial é o cancro, com uma taxa de mortes em 2018 de 9.6 milhões de pessoas. Em particular, as doenças relacionadas com cancro já originaram 26% do número total de mortes ocorridas em Portugal em 2016. Vários mecanismos estão associados ao desenvolvimento de cancro, sendo que o stress oxidativo parece exercer um papel crucial na origem desta doença. Assim, a deteção precoce de múltiplos biomarcadores do stress oxidativo constitui uma ferramenta essencial na prevenção do cancro e também na seleção das terapias mais eficazes. A procura de metodologias para análise específica de biomarcadores do stress oxidativo in loco continua a ser um desafio para a investigação biomédica. Até ao momento, os métodos analíticos utilizados para o diagnóstico de cancro, que incluem um exame patológico, são insuficientes para deteção precoce da progressão do tumor. Assim, para ultrapassar esta necessidade, o principal objetivo deste projeto é desenvolver métodos de deteção rápidos, simples e precisos para quantificação de biomarcadores de stress oxidativo, com metodologias de recolha não-invasivas, de modo a conduzir a um diagnóstico rápido e de confiança numa fase inicial da doença. Para este efeito, esta tese apresenta o fabrico de biomateriais com propriedades sensoriais integradas em substratos condutores inovadores, para deteção in loco de biomarcadores de stress oxidativo. De modo a obter processos de reconhecimento bioquímico de elevada seletividade e especificidade, foi utilizada uma tecnologia de impressão molecular, que permite criar locais artificiais de reconhecimento. No decorrer da fabricação das plataformas transdutoras eletroquímicas, o papel foi usado como material de suporte alternativo aos materiais convencionais geralmente incorporados nos sistemas de elétrodos. Em suma, espera-se que os resultados deste plano possam contribuir, no futuro, para o desenvolvimento e aplicação de plataformas de multi-analitos para rápida e simultânea deteção de biomarcadores do stress oxidativo num contexto local. According to the most recent World Health Organization (WHO) data, cancer is the second leading cause of death worldwide, accounting for 9.6 million deaths in 2018. In particular, cancer diseases have caused 26% of the total deaths in Portugal in 2016. Among the complex mechanisms associated to cancer development, Oxidative Stress (OS) seems to play an important role at the origin of the disease. Thus, early diagnosis of multiple OS biomarkers may be a fundamental tool in cancer prevention and in more efficient therapeutic strategies. Despite the development and the research efforts that are being made, accurate and early detection methods for cancer are still lacking. The demand for specific OS biomarker assays carried out in wide screening programs in point-of-care (POC) is undoubtedly a difficult but potentially useful challenge for biomedical research and health. So far, current methods for cancer diagnosis based upon pathological examination alone are insufficient for detecting early tumour progression. Thus, to overcome this need, the present project aims the development of quick, simple and accurate detection of selected OS biomarkers, collected using minimally invasive methods, in order to allow rapid and reliable diagnosis at early stages of the disease. Under this scope, the design of sensitive biosensing materials integrated with novel conductive substrates for POC screening of OS biomarkers will be presented. In order to achieve a specific and highly selective bio-chemical recognition process, molecular imprinting strategy was used to create the artificial recognition sites. During the fabrication of electrochemical transduction platforms, paper was introduced as a novel alternative to the conventional support materials usually incorporated in electrode systems. Overall, it is expected that the outcome of this plan will contribute, in the future, to the development and application of a multi-analyte platform for simultaneous fast screening of cancer biomarkers in POC context.}, note = {grau de Doutor em Nanotecnologias e Nanociências }, keywords = {}, pubstate = {published}, tppubtype = {phdthesis} } Segundo as recentes estatísticas da Organização Mundial de Saúde (OMS), a segunda principal causa de morte a nível mundial é o cancro, com uma taxa de mortes em 2018 de 9.6 milhões de pessoas. Em particular, as doenças relacionadas com cancro já originaram 26% do número total de mortes ocorridas em Portugal em 2016. Vários mecanismos estão associados ao desenvolvimento de cancro, sendo que o stress oxidativo parece exercer um papel crucial na origem desta doença. Assim, a deteção precoce de múltiplos biomarcadores do stress oxidativo constitui uma ferramenta essencial na prevenção do cancro e também na seleção das terapias mais eficazes. A procura de metodologias para análise específica de biomarcadores do stress oxidativo in loco continua a ser um desafio para a investigação biomédica. Até ao momento, os métodos analíticos utilizados para o diagnóstico de cancro, que incluem um exame patológico, são insuficientes para deteção precoce da progressão do tumor. Assim, para ultrapassar esta necessidade, o principal objetivo deste projeto é desenvolver métodos de deteção rápidos, simples e precisos para quantificação de biomarcadores de stress oxidativo, com metodologias de recolha não-invasivas, de modo a conduzir a um diagnóstico rápido e de confiança numa fase inicial da doença. Para este efeito, esta tese apresenta o fabrico de biomateriais com propriedades sensoriais integradas em substratos condutores inovadores, para deteção in loco de biomarcadores de stress oxidativo. De modo a obter processos de reconhecimento bioquímico de elevada seletividade e especificidade, foi utilizada uma tecnologia de impressão molecular, que permite criar locais artificiais de reconhecimento. No decorrer da fabricação das plataformas transdutoras eletroquímicas, o papel foi usado como material de suporte alternativo aos materiais convencionais geralmente incorporados nos sistemas de elétrodos. Em suma, espera-se que os resultados deste plano possam contribuir, no futuro, para o desenvolvimento e aplicação de plataformas de multi-analitos para rápida e simultânea deteção de biomarcadores do stress oxidativo num contexto local. According to the most recent World Health Organization (WHO) data, cancer is the second leading cause of death worldwide, accounting for 9.6 million deaths in 2018. In particular, cancer diseases have caused 26% of the total deaths in Portugal in 2016. Among the complex mechanisms associated to cancer development, Oxidative Stress (OS) seems to play an important role at the origin of the disease. Thus, early diagnosis of multiple OS biomarkers may be a fundamental tool in cancer prevention and in more efficient therapeutic strategies. Despite the development and the research efforts that are being made, accurate and early detection methods for cancer are still lacking. The demand for specific OS biomarker assays carried out in wide screening programs in point-of-care (POC) is undoubtedly a difficult but potentially useful challenge for biomedical research and health. So far, current methods for cancer diagnosis based upon pathological examination alone are insufficient for detecting early tumour progression. Thus, to overcome this need, the present project aims the development of quick, simple and accurate detection of selected OS biomarkers, collected using minimally invasive methods, in order to allow rapid and reliable diagnosis at early stages of the disease. Under this scope, the design of sensitive biosensing materials integrated with novel conductive substrates for POC screening of OS biomarkers will be presented. In order to achieve a specific and highly selective bio-chemical recognition process, molecular imprinting strategy was used to create the artificial recognition sites. During the fabrication of electrochemical transduction platforms, paper was introduced as a novel alternative to the conventional support materials usually incorporated in electrode systems. Overall, it is expected that the outcome of this plan will contribute, in the future, to the development and application of a multi-analyte platform for simultaneous fast screening of cancer biomarkers in POC context. |
2017
2016
2015
TSCR Rebelo Improving the early diagnostic of prostate cancer by multiple biomarker detection with new biosensing devices (PhD Thesis) Supervision: JPC Noronha, JMSC Rodrigues, MGF Sales. Doctoral Dissertation Sustainable Chemistry, Faculdade de Ciências e Tecnologia da Universidade Nova da Lisboa, Presented in December 16, 2015. @phdthesis{Rebelo2015, title = {Improving the early diagnostic of prostate cancer by multiple biomarker detection with new biosensing devices}, author = {TSCR Rebelo }, url = {https://run.unl.pt/handle/10362/16313}, year = {2015}, date = {2015-12-16}, school = {Supervision: JPC Noronha, JMSC Rodrigues, MGF Sales. Doctoral Dissertation Sustainable Chemistry, Faculdade de Ciências e Tecnologia da Universidade Nova da Lisboa, Presented in December 16}, abstract = {Prostate cancer (CaP) is the most common form of cancer in men, in Europe (World Health Organization data). The most recent statistics, in Portuguese territory, confirm this scenario, which states that about 50% of Portuguese men may suffer from prostate cancer and 15% of these will die from this condition. Its early detection is therefore fundamental. This is currently being done by Prostate Specific Antigen (PSA) screening in urine but false positive and negative results are quite often obtained and many patients are sent to unnecessary biopsy procedures. This early detection protocol may be improved, by the development of point-of- care cancer detection devices, not only to PSA but also to other biomarkers recently identified. Thus, the present work aims to screen several biomarkers in cultured human prostate cell lines, serum and urine samples, developing low cost sensors based on new synthetic biomaterials. Biomarkers considered in this study are the following: prostate specific antigen (PSA), annexin A3 (ANXA3), microseminoprotein-beta (MSMB) and sarcosine (SAR). The biomarker recognition may occurs by means of molecularly imprinted polymers (MIP), which are a kind of plastic antibodies, and enzymatic approaches. The growth of a rigid polymer, chemically stable, using the biomarker as a template allows the synthesis of the plastic antibody. MIPs show high sensitivity/selectivity and present much longer stability and much lower price than natural antibodies. This nanostructured material was prepared on a carbon solid. The interaction between the biomarker and the sensing-material produces electrical signals generating quantitative or semi-quantitative data. These devices allow inexpensive and portable detection in point-of- care testing.}, keywords = {}, pubstate = {published}, tppubtype = {phdthesis} } Prostate cancer (CaP) is the most common form of cancer in men, in Europe (World Health Organization data). The most recent statistics, in Portuguese territory, confirm this scenario, which states that about 50% of Portuguese men may suffer from prostate cancer and 15% of these will die from this condition. Its early detection is therefore fundamental. This is currently being done by Prostate Specific Antigen (PSA) screening in urine but false positive and negative results are quite often obtained and many patients are sent to unnecessary biopsy procedures. This early detection protocol may be improved, by the development of point-of- care cancer detection devices, not only to PSA but also to other biomarkers recently identified. Thus, the present work aims to screen several biomarkers in cultured human prostate cell lines, serum and urine samples, developing low cost sensors based on new synthetic biomaterials. Biomarkers considered in this study are the following: prostate specific antigen (PSA), annexin A3 (ANXA3), microseminoprotein-beta (MSMB) and sarcosine (SAR). The biomarker recognition may occurs by means of molecularly imprinted polymers (MIP), which are a kind of plastic antibodies, and enzymatic approaches. The growth of a rigid polymer, chemically stable, using the biomarker as a template allows the synthesis of the plastic antibody. MIPs show high sensitivity/selectivity and present much longer stability and much lower price than natural antibodies. This nanostructured material was prepared on a carbon solid. The interaction between the biomarker and the sensing-material produces electrical signals generating quantitative or semi-quantitative data. These devices allow inexpensive and portable detection in point-of- care testing. |
JRL Guerreiro Interaction studies proteins/polyphenols: sensorial astringency measurements by analytical tool applications to wine control (PhD Thesis) Supervision: VAP Freitas, D Sutherland, MGF Sales. Doctoral Dissertation Chemistry, Faculdade de Ciêncidas da Universidade do Porto, Presented in July 21, 2015. @phdthesis{Guerreiro2015b, title = { Interaction studies proteins/polyphenols: sensorial astringency measurements by analytical tool applications to wine control}, author = {JRL Guerreiro }, year = {2015}, date = {2015-07-21}, school = {Supervision: VAP Freitas, D Sutherland, MGF Sales. Doctoral Dissertation Chemistry, Faculdade de Ciêncidas da Universidade do Porto, Presented in July 21}, abstract = {Polyphenols are widely spread in nature and consumed in fruits and vegetables on a daily basis. They are considered of great interest for two main reasons: their antioxidant capacity (scavenging of free radicals and reducing power) and the high capability to interact with proteins (e.g. enzymes). The interaction of polyphenols with proteins contributes for organoleptic properties of foods and is implicated in several biological mechanisms inducing human health benefits. The organoleptic sensation resulting from the interaction of polyphenols with salivary proteins is known as astringency. Astringency is a tactile sensation described as the mouth dryness, puckering and constriction of mouth tissues. Perceived in the oral cavity, astringency arises by the formation of complexes between proteins and polyphenols, which may lead to further precipitation. Generally, trained experts measure astringency, which is an expensive and subjective evaluation. Regarding the interaction with proteins related to diverse biological mechanisms, polyphenols may inhibit or activate enzymes acting as modulators of specific pathways and consequently can act as agents against diseases. Therefore, the development of new analytical tools to understand protein and polyphenol interactions, in terms of proteins conformational changes, binding affinities and quantification, is of great importance and should be deeply explored. This PhD thesis aimed to develop novel and simple optical sensing devices to study protein and polyphenol interactions. The devices may have different applications and herein will be used to estimate polyphenol astringency. Three optical sensors were developed for this purpose, based in colorimetric responses, localized surface Plasmon resonance (LSPR) and the combination of LSPR detection with artificial biomaterials (molecularly-imprinted polymers). The proteins included in this study were bovine serum albumin (BSA) due to it stability, a-amylase for being the most common salivary protein and full saliva tested herein as a complex matrix. Their interaction with polyphenols was established with tannic acid, pentagalloyl glucose (PGG), (+)-catechin and B3 dimer. The sensing platforms allowed the study of polyphenol molecules interacting with proteins, the quantification of binding affinities, the conformational changes of proteins occurring upon polyphenol interactions, and the interaction of protein complex matrices with polyphenols. Such platforms, in case of astringency estimation, were applied to real wine samples and compared with results provided by sensorial analysis. A good correlation between the two analyses indicated a successful application to real samples. The developed nanosensors are expected to contribute for a better characterization of protein and polyphenol interactions, applied not only to astringency but also to other biological mechanisms. More than measuring the polyphenols and proteins effect at the molecular level, these sensors could be useful at the development of new drugs or drug targets.}, keywords = {}, pubstate = {published}, tppubtype = {phdthesis} } Polyphenols are widely spread in nature and consumed in fruits and vegetables on a daily basis. They are considered of great interest for two main reasons: their antioxidant capacity (scavenging of free radicals and reducing power) and the high capability to interact with proteins (e.g. enzymes). The interaction of polyphenols with proteins contributes for organoleptic properties of foods and is implicated in several biological mechanisms inducing human health benefits. The organoleptic sensation resulting from the interaction of polyphenols with salivary proteins is known as astringency. Astringency is a tactile sensation described as the mouth dryness, puckering and constriction of mouth tissues. Perceived in the oral cavity, astringency arises by the formation of complexes between proteins and polyphenols, which may lead to further precipitation. Generally, trained experts measure astringency, which is an expensive and subjective evaluation. Regarding the interaction with proteins related to diverse biological mechanisms, polyphenols may inhibit or activate enzymes acting as modulators of specific pathways and consequently can act as agents against diseases. Therefore, the development of new analytical tools to understand protein and polyphenol interactions, in terms of proteins conformational changes, binding affinities and quantification, is of great importance and should be deeply explored. This PhD thesis aimed to develop novel and simple optical sensing devices to study protein and polyphenol interactions. The devices may have different applications and herein will be used to estimate polyphenol astringency. Three optical sensors were developed for this purpose, based in colorimetric responses, localized surface Plasmon resonance (LSPR) and the combination of LSPR detection with artificial biomaterials (molecularly-imprinted polymers). The proteins included in this study were bovine serum albumin (BSA) due to it stability, a-amylase for being the most common salivary protein and full saliva tested herein as a complex matrix. Their interaction with polyphenols was established with tannic acid, pentagalloyl glucose (PGG), (+)-catechin and B3 dimer. The sensing platforms allowed the study of polyphenol molecules interacting with proteins, the quantification of binding affinities, the conformational changes of proteins occurring upon polyphenol interactions, and the interaction of protein complex matrices with polyphenols. Such platforms, in case of astringency estimation, were applied to real wine samples and compared with results provided by sensorial analysis. A good correlation between the two analyses indicated a successful application to real samples. The developed nanosensors are expected to contribute for a better characterization of protein and polyphenol interactions, applied not only to astringency but also to other biological mechanisms. More than measuring the polyphenols and proteins effect at the molecular level, these sensors could be useful at the development of new drugs or drug targets. |
2013
FTC Moreira Fast screening for early diagnostic of heart ischemis diseases (PhD Thesis) Supervision: JPC Noronha, MGF Sales, GG Aguilar. Doctoral Dissertation Sustainable Chemistry, Faculdade de Ciências e Tecnologia da Universidade Nova de Lisboa, Presented in December 12, 2013. @phdthesis{Moreira2013, title = {Fast screening for early diagnostic of heart ischemis diseases}, author = {FTC Moreira }, url = {http://hdl.handle.net/10362/11318}, year = {2013}, date = {2013-12-12}, school = {Supervision: JPC Noronha, MGF Sales, GG Aguilar. Doctoral Dissertation Sustainable Chemistry, Faculdade de Ciências e Tecnologia da Universidade Nova de Lisboa, Presented in December 12}, abstract = {As doenças cardiovasculares foram responsáveis, em 2010, por cerca de metade das mortes por doença crónica em toda a Europa (dados Eurostat). Os dados estatísticos mais recentes relativos ao território português confirmam este cenário, no qual as doenças cardiovasculares matam cerca de 11 pessoas por 100000 habitantes. A redução destes números é urgente e passa necessariamente por um diagnóstico precoce, rápido e eficaz da condição cardíaca. Neste sentido, o principal objetivo deste projeto foi desenvolver sistemas sensores uma plataforma sensora de baixo custo, baseada em novos biomateriais sintéticos para o rastreio de biomarcadores cardíacos em ‘point-of-care’. São considerados neste estudo biomarcardores de interesse clínico convencionais, nomeadamente troponina T (TnT), creatina quinase isoenzima (CK-MB) e mioglobina (Myo). O desenho de novos materiais biossensores baseou-se na síntese dos anticorpos plásticos por novas tecnologias de impressão molecular (MI). No geral, o anticorpo de plástico foi obtido usando o biomarcador cardíaco como obstáculo ao crescimento de um polímero rígido e quimicamente estável. As unidades sensoras nanoestruturadas foram preparadas por modificação de um suporte sólido de carbono ou de ouro com esses biomateriais. Espera-se, com este trabalho, que as ferramentas desenvolvidas abram novos caminhos para o diagnóstico, não invasivo ou minimamente invasivo, tendo em vista a deteção precoce de doenças crónicas ou um despiste rápido em situações de doença aguda.}, keywords = {}, pubstate = {published}, tppubtype = {phdthesis} } As doenças cardiovasculares foram responsáveis, em 2010, por cerca de metade das mortes por doença crónica em toda a Europa (dados Eurostat). Os dados estatísticos mais recentes relativos ao território português confirmam este cenário, no qual as doenças cardiovasculares matam cerca de 11 pessoas por 100000 habitantes. A redução destes números é urgente e passa necessariamente por um diagnóstico precoce, rápido e eficaz da condição cardíaca. Neste sentido, o principal objetivo deste projeto foi desenvolver sistemas sensores uma plataforma sensora de baixo custo, baseada em novos biomateriais sintéticos para o rastreio de biomarcadores cardíacos em ‘point-of-care’. São considerados neste estudo biomarcardores de interesse clínico convencionais, nomeadamente troponina T (TnT), creatina quinase isoenzima (CK-MB) e mioglobina (Myo). O desenho de novos materiais biossensores baseou-se na síntese dos anticorpos plásticos por novas tecnologias de impressão molecular (MI). No geral, o anticorpo de plástico foi obtido usando o biomarcador cardíaco como obstáculo ao crescimento de um polímero rígido e quimicamente estável. As unidades sensoras nanoestruturadas foram preparadas por modificação de um suporte sólido de carbono ou de ouro com esses biomateriais. Espera-se, com este trabalho, que as ferramentas desenvolvidas abram novos caminhos para o diagnóstico, não invasivo ou minimamente invasivo, tendo em vista a deteção precoce de doenças crónicas ou um despiste rápido em situações de doença aguda. |
RB Queirós (Bio)sensors for the detection/quantitation of water contamination by bacteria in waters for human consumption (PhD Thesis) Supervision: MGF Sales, PV Marques. Doctoral Dissertation in Physics, Faculdade de Ciências da Universidade do Porto, Presented in April 19, 2013. @phdthesis{Queirós2013b, title = {(Bio)sensors for the detection/quantitation of water contamination by bacteria in waters for human consumption}, author = {RB Queirós}, url = {https://repositorio-aberto.up.pt/handle/10216/66637}, year = {2013}, date = {2013-04-19}, school = {Supervision: MGF Sales, PV Marques. Doctoral Dissertation in Physics, Faculdade de Ciências da Universidade do Porto, Presented in April 19}, abstract = {A água tem sido considerada de grande importância para a saúde e bem-estar dos seres humanos. A água pode contudo expor os indivíduos a uma variedade de perigos para a saúde, quer através da sua ingestão quer pelo contato direto com água contaminada. A contaminação aquática pode ter origem química ou biológica. As cianobactérias e a E. coli são patógenos de grande preocupação pois produzem toxinas que podem causar irritação na pele, dores de estômago, vómitos, náuseas, diarreia, febre, infeções do trato urinário, doenças respiratórias e danos graves ao nível do fígado. Os métodos clássicos para a deteção e quantificação destas bactérias são baseados em métodos de cultura e contagem, ensaios bioquímicos e imunológicos, métodos moleculares e em técnicas de separação. Estes métodos apresentam algumas desvantagens sendo as mais significativas o custo do equipamento necessário e os longos períodos de análise. A fim de evitar surtos de cyanobactérias e E. coli, e os seus efeitos, é fundamental ter métodos capazes de identificar/quantificar estas bactérias patogénicas rapidamente. Por esse motivo, é necessária a procura de métodos rápidos de rastreio, que permitam a análise in situ e que proporcionem uma deteção rápida e sensível. Este trabalho propõe dispositivos que combinam novos elementos de reconhecimento para cianobactérias e E. coli integrados em sistemas de transdução físico-quimica. O elemento biológico é de origem sintética, produzidos com materiais não biológicos, ou com oligo estruturas de ácidos nucleicos. A transdução é de natureza eléctrica (potenciométrica e impedimétrica) ou ótica (baseada em interferometrica e baseada em redes de período longo). Os elementos de reconhecimento desenvolvidos para o reconhecimento da Mcyst-LR, uma toxina produzida pelas cyanobactérias, foram concebidos através da técnica de impressão molecular. Estes polímeros foram produzidos em sol-gel ou em estruturas vinílicas, tendo uma constituição cuidadosamente selecionada. Os polímeros impressos em sol-gel foram depositados em electrodos de contacto sólido ou em fibras óticas para monitorização potenciométrica or interferométrica. Os polímeros impressos com estruturas de vinil foram incorporados, como iónoforos, em membranas selectivas de policloreto de vinil e depositadas em electrodos de contato sólido para monitorização potenciométrica. Os elementos de reconhecimento biológico para a E. coli são nucleótidos de ácido desoxirribonucleico, usualmente conhecidos como aptámeros. Estes elementos têm uma sequência específica que induz a interacção com as proteínas da membrana externa da E. coli. Os aptámeros são imobilizados em eléctrodos de ouro ou em fibras ópticas com redes de período longo. A transdução do sinal é por espectroscopia de impedância electroquímica ou por interacção do campo evanescente. No geral, os sistemas apresentados introduzem várias inovações quer em termos dos elementos de reconhecimento biológico quer em termos dos sistemas analíticos. Tanto os aptâmeros como os polímeros impressos são elementos de reconhecimento biológico adequados, fornecendo o reconhecimento sensível e selectivo dos anlitos. Os sistemas óticos e electroquímicos desenvolvidos apresentam vantagens quando comparados com os métodos convencionais. Utilizam materiais de baixo custo e são simples de operar, reduzindo a intervenção do operador. Além disso, proporcionam uma resposta rápida e permitem a monitorização in situ. Pode assim concluir-se que os biosensores propostos constituem uma alternativa viável aos métodos convencionais utilizados para a deteção/quantificação quer das cyanobactérias como da E. coli em águas.}, keywords = {}, pubstate = {published}, tppubtype = {phdthesis} } A água tem sido considerada de grande importância para a saúde e bem-estar dos seres humanos. A água pode contudo expor os indivíduos a uma variedade de perigos para a saúde, quer através da sua ingestão quer pelo contato direto com água contaminada. A contaminação aquática pode ter origem química ou biológica. As cianobactérias e a E. coli são patógenos de grande preocupação pois produzem toxinas que podem causar irritação na pele, dores de estômago, vómitos, náuseas, diarreia, febre, infeções do trato urinário, doenças respiratórias e danos graves ao nível do fígado. Os métodos clássicos para a deteção e quantificação destas bactérias são baseados em métodos de cultura e contagem, ensaios bioquímicos e imunológicos, métodos moleculares e em técnicas de separação. Estes métodos apresentam algumas desvantagens sendo as mais significativas o custo do equipamento necessário e os longos períodos de análise. A fim de evitar surtos de cyanobactérias e E. coli, e os seus efeitos, é fundamental ter métodos capazes de identificar/quantificar estas bactérias patogénicas rapidamente. Por esse motivo, é necessária a procura de métodos rápidos de rastreio, que permitam a análise in situ e que proporcionem uma deteção rápida e sensível. Este trabalho propõe dispositivos que combinam novos elementos de reconhecimento para cianobactérias e E. coli integrados em sistemas de transdução físico-quimica. O elemento biológico é de origem sintética, produzidos com materiais não biológicos, ou com oligo estruturas de ácidos nucleicos. A transdução é de natureza eléctrica (potenciométrica e impedimétrica) ou ótica (baseada em interferometrica e baseada em redes de período longo). Os elementos de reconhecimento desenvolvidos para o reconhecimento da Mcyst-LR, uma toxina produzida pelas cyanobactérias, foram concebidos através da técnica de impressão molecular. Estes polímeros foram produzidos em sol-gel ou em estruturas vinílicas, tendo uma constituição cuidadosamente selecionada. Os polímeros impressos em sol-gel foram depositados em electrodos de contacto sólido ou em fibras óticas para monitorização potenciométrica or interferométrica. Os polímeros impressos com estruturas de vinil foram incorporados, como iónoforos, em membranas selectivas de policloreto de vinil e depositadas em electrodos de contato sólido para monitorização potenciométrica. Os elementos de reconhecimento biológico para a E. coli são nucleótidos de ácido desoxirribonucleico, usualmente conhecidos como aptámeros. Estes elementos têm uma sequência específica que induz a interacção com as proteínas da membrana externa da E. coli. Os aptámeros são imobilizados em eléctrodos de ouro ou em fibras ópticas com redes de período longo. A transdução do sinal é por espectroscopia de impedância electroquímica ou por interacção do campo evanescente. No geral, os sistemas apresentados introduzem várias inovações quer em termos dos elementos de reconhecimento biológico quer em termos dos sistemas analíticos. Tanto os aptâmeros como os polímeros impressos são elementos de reconhecimento biológico adequados, fornecendo o reconhecimento sensível e selectivo dos anlitos. Os sistemas óticos e electroquímicos desenvolvidos apresentam vantagens quando comparados com os métodos convencionais. Utilizam materiais de baixo custo e são simples de operar, reduzindo a intervenção do operador. Além disso, proporcionam uma resposta rápida e permitem a monitorização in situ. Pode assim concluir-se que os biosensores propostos constituem uma alternativa viável aos métodos convencionais utilizados para a deteção/quantificação quer das cyanobactérias como da E. coli em águas. |
2012
SAA Almeida (Bio)Sensores para a detecção/quantificação de antimicrobianos de aquicultura no meio aquático (PhD Thesis) Supervision: MCBSM Montenegro, MGF Sales. Doctoral Dissertation in Analytical Chemistry, Faculdade de Farmácia da Universidade do Porto, Presented in April 9, 2012. @phdthesis{Almeida2012b, title = {(Bio)Sensores para a detecção/quantificação de antimicrobianos de aquicultura no meio aquático}, author = {SAA Almeida}, url = {http://hdl.handle.net/10216/62344}, year = {2012}, date = {2012-04-09}, school = {Supervision: MCBSM Montenegro, MGF Sales. Doctoral Dissertation in Analytical Chemistry, Faculdade de Farmácia da Universidade do Porto, Presented in April 9}, abstract = {Os sistemas de aquacultura são fundamentais na nossa sociedade porque garantem um fornecimento regular de peixe às populações, preservando os recursos naturais no sector das pescas, muitas vezes já escassos, e garantindo a sobrevivência de espécies em risco. O aumento da produtividade está, contudo, associado à introdução de drogas que garantem o crescimento e a preservação das espécies, mas que acabam por se difundir para o meio aquático envolvente, promovendo alterações na biodiversidade e entrando, directa ou indirectamente, na cadeia alimentar. Quando estas drogas são agentes antimicrobianos de uso humano, como é o caso das sulfonamidas, existe um risco elevado de aparecimento de espécies bacterianas resistentes, algo que constitui uma grave ameaça à saúde pública. A introdução de agentes antimicrobianos no meio aquático pelo sector da aquacultura pode ser minimizada através da monitorização contínua/regular dos níveis de antibiótico nas águas do sistema, tanto durante a sua aplicação, como antes da sua descarga para o meio aquático envolvente. Para este efeito, tornam-se necessários métodos analíticos de baixo custo que permitam uma frequência analítica elevada e contínua, nos tanques de cultivo dos peixes. Neste contexto, os eléctrodos selectivos de ião (ESIs) podem constituir uma preciosa ferramenta já que podem ser aplicados na análise de matrizes complexas, apresentando baixo custo e portabilidade e podendo também ser associados a metodologias automáticas, tal como a análise por injecção em fluxo (FIA, do inglês Flow Injection Analysis). Neste trabalho, estudam-se os efeitos de diversos materiais sensores, comerciais ou sintetizados por técnicas de impressão molecular, na construção de (bio)sensores potenciométricos, apropriados para a monitorização de algumas das sulfonamidas mais utilizadas no sector da aquacultura. Estudam-se ainda diversos modos da sua adequação a sistemas de fluxo, incluindo configurações tubulares em sistemas FIA e planares em suportes cerâmicos de microfluídica. A possibilidade de redução significativa dos limites de detecção dos eléctrodos foi também objecto de estudo nesta dissertação. Todas as vertentes metodológicas desenvolvidas foram aplicadas, com sucesso, à análise de amostras de água de aquacultura. Face aos resultados obtidos, considera-se que os vários métodos propostos constituem alternativas vantajosas aos métodos habitualmente utilizados para a determinação de sulfonamidas, nomeadamente aqueles que envolvem técnicas separativas, nas quais os reagentes utilizados são, só por si, geradores de contaminação ambiental. Os métodos potenciométricos desenvolvidos usam, de uma forma geral, materiais de baixo custo e sistemas simples, fornecem uma resposta rápida e requerem uma reduzida intervenção do operador. Do ponto de vista do seu impacto no meio ambiente, são também muito menos poluentes do que a grande parte dos métodos usados para avaliação deste tipo de compostos.}, keywords = {}, pubstate = {published}, tppubtype = {phdthesis} } Os sistemas de aquacultura são fundamentais na nossa sociedade porque garantem um fornecimento regular de peixe às populações, preservando os recursos naturais no sector das pescas, muitas vezes já escassos, e garantindo a sobrevivência de espécies em risco. O aumento da produtividade está, contudo, associado à introdução de drogas que garantem o crescimento e a preservação das espécies, mas que acabam por se difundir para o meio aquático envolvente, promovendo alterações na biodiversidade e entrando, directa ou indirectamente, na cadeia alimentar. Quando estas drogas são agentes antimicrobianos de uso humano, como é o caso das sulfonamidas, existe um risco elevado de aparecimento de espécies bacterianas resistentes, algo que constitui uma grave ameaça à saúde pública. A introdução de agentes antimicrobianos no meio aquático pelo sector da aquacultura pode ser minimizada através da monitorização contínua/regular dos níveis de antibiótico nas águas do sistema, tanto durante a sua aplicação, como antes da sua descarga para o meio aquático envolvente. Para este efeito, tornam-se necessários métodos analíticos de baixo custo que permitam uma frequência analítica elevada e contínua, nos tanques de cultivo dos peixes. Neste contexto, os eléctrodos selectivos de ião (ESIs) podem constituir uma preciosa ferramenta já que podem ser aplicados na análise de matrizes complexas, apresentando baixo custo e portabilidade e podendo também ser associados a metodologias automáticas, tal como a análise por injecção em fluxo (FIA, do inglês Flow Injection Analysis). Neste trabalho, estudam-se os efeitos de diversos materiais sensores, comerciais ou sintetizados por técnicas de impressão molecular, na construção de (bio)sensores potenciométricos, apropriados para a monitorização de algumas das sulfonamidas mais utilizadas no sector da aquacultura. Estudam-se ainda diversos modos da sua adequação a sistemas de fluxo, incluindo configurações tubulares em sistemas FIA e planares em suportes cerâmicos de microfluídica. A possibilidade de redução significativa dos limites de detecção dos eléctrodos foi também objecto de estudo nesta dissertação. Todas as vertentes metodológicas desenvolvidas foram aplicadas, com sucesso, à análise de amostras de água de aquacultura. Face aos resultados obtidos, considera-se que os vários métodos propostos constituem alternativas vantajosas aos métodos habitualmente utilizados para a determinação de sulfonamidas, nomeadamente aqueles que envolvem técnicas separativas, nas quais os reagentes utilizados são, só por si, geradores de contaminação ambiental. Os métodos potenciométricos desenvolvidos usam, de uma forma geral, materiais de baixo custo e sistemas simples, fornecem uma resposta rápida e requerem uma reduzida intervenção do operador. Do ponto de vista do seu impacto no meio ambiente, são também muito menos poluentes do que a grande parte dos métodos usados para avaliação deste tipo de compostos. |
TESES DE MESTRADO
2017
2018
MARTA PEREIRA Fabrication of 3D electrodes for biosensor applications (Masters Thesis) Universidade Nova de Lisboa, 2018, (grau de MESTRE em Engenharia de Micro e Nanotecnologias da Universidade Nova de Lisboa. ). (BibTeX) @mastersthesis{Pereira2018, title = {Fabrication of 3D electrodes for biosensor applications }, author = {MARTA PEREIRA}, editor = {MF Frasco, MGF Sales, E Fortunato}, year = {2018}, date = {2018-01-01}, school = {Universidade Nova de Lisboa}, note = {grau de MESTRE em Engenharia de Micro e Nanotecnologias da Universidade Nova de Lisboa. }, keywords = {}, pubstate = {published}, tppubtype = {mastersthesis} } |
TOMÁS FERNANDES Digital Fabrication of Transparent Electrodes for Simultaneously Optical and Electrochemical Biosensor Applications (Masters Thesis) Universidade Nova de Lisboa, 2018, (rau de MESTRE em Engenharia de Micro e Nanotecnologias ). (BibTeX) @mastersthesis{Fernandes2018, title = {Digital Fabrication of Transparent Electrodes for Simultaneously Optical and Electrochemical Biosensor Applications}, author = {TOMÁS FERNANDES}, editor = {FTC Moreira, MGF Sales, E Fortunato }, year = {2018}, date = {2018-01-01}, school = {Universidade Nova de Lisboa}, note = {rau de MESTRE em Engenharia de Micro e Nanotecnologias }, keywords = {}, pubstate = {published}, tppubtype = {mastersthesis} } |
DALILA OLIVEIRA Aplicação de materiais molecularmente impressos para captura de proteínas relacionadas com a angiogénese (Masters Thesis) Universidade Nova de Lisboa, 2018, (grau de MESTRE pela Universidade Nova de Lisboa). (BibTeX) @mastersthesis{Oliveira2018, title = {Aplicação de materiais molecularmente impressos para captura de proteínas relacionadas com a angiogénese}, author = {DALILA OLIVEIRA }, editor = {MGF Sales, P Granja}, year = {2018}, date = {2018-01-01}, school = {Universidade Nova de Lisboa}, note = {grau de MESTRE pela Universidade Nova de Lisboa}, keywords = {}, pubstate = {published}, tppubtype = {mastersthesis} } |
2019
PEDRO PIRES MARTINS Desenvolvimento de um Biossensor para a deteção do Ácido 3-Hidroxibutírico na Cetoacidose Diabética (Masters Thesis) Escola Superior de Saúde do Instituto Politécnico do Porto, 2019, (grau de MESTRE em Bioquímica em Saúde, Ramo de Bioquímica Clínica e Metabólica ). (BibTeX) @mastersthesis{Martins2019, title = {Desenvolvimento de um Biossensor para a deteção do Ácido 3-Hidroxibutírico na Cetoacidose Diabética}, author = {PEDRO PIRES MARTINS}, editor = {MGF Sales, LAANA Truta, R Fernandes, }, year = {2019}, date = {2019-07-17}, school = {Escola Superior de Saúde do Instituto Politécnico do Porto}, note = {grau de MESTRE em Bioquímica em Saúde, Ramo de Bioquímica Clínica e Metabólica }, keywords = {}, pubstate = {published}, tppubtype = {mastersthesis} } |
DANIEL JOÃO CERQUEIRA DA COSTA Ion-selective electrode research automation, BioMark Research Process Optimization (Masters Thesis) Escola Superior de Saúde do Instituto Politécnico do Porto, 2019, (grau de MESTRE em Engenharia de Instrumentação Médica pelo ISEP). (BibTeX) @mastersthesis{Costa2019, title = {Ion-selective electrode research automation, BioMark Research Process Optimization }, author = {DANIEL JOÃO CERQUEIRA DA COSTA}, editor = {MGF Sales }, year = {2019}, date = {2019-07-17}, school = {Escola Superior de Saúde do Instituto Politécnico do Porto}, note = {grau de MESTRE em Engenharia de Instrumentação Médica pelo ISEP}, keywords = {}, pubstate = {published}, tppubtype = {mastersthesis} } |
2020
2016
M Carneiro Development of an electrochemical biosensor for microRNA-107 in Alzheimer’s Disease (Masters Thesis) Supervision: FTC Moreira, R Fernandes, MGF Sales. Escola Superior de Tecnologia da Saúde do Porto, 2016. @mastersthesis{Carneiro2016b, title = {Development of an electrochemical biosensor for microRNA-107 in Alzheimer’s Disease}, author = {M Carneiro}, year = {2016}, date = {2016-12-16}, school = {Supervision: FTC Moreira, R Fernandes, MGF Sales. Escola Superior de Tecnologia da Saúde do Porto}, abstract = {Alzheimer’s Disease is a chronic neurodegenerative disease with high economic and social impact, being the major source of dementia worldwide. It is responsible for a progressive memory loss and other changes at behavior and motor level, essentially originated by Aβ and tau proteins accumulation in brain’s tissues. The ineffectiveness of actual diagnostic methods in early disease detection and the limitations in therapy approaches, demands finding non-invasive molecular biomarker with high sensitivity and specificity, for use in early diagnosis, evaluation of disease progression and therapeutic application, as well as the design of new analytical devices that may be used routinely in clinical context. MiRNAs are non-coding RNAs responsible for post-transcriptional genetic regulation, playing an important role in several biological processes, including neuronal related activities. miRNAs arise today as emerging potential Alzheimer biomarkers, highlighting miRNa-107 that is early reduced at patient’s brains and responsible for regulation of several molecules directly involved in Alzheimer’s pathology. On the other hand, electrochemical biosensors are a promising technology for miRNA detection and quantification, providing fast responses with low cost and simple procedures, associated to high sensitivity and specificity. Thus, this work focused (1) in the production of a three electrode system disposable, homemade, and carbon screen printed electrodes (C-SPEs) for biosensor’s use and (2) in the development of a biosensor for miRNA-107, based on its hybridization with a complementary probe and subsequent electrochemical detection, with potential application in a POC device for diagnosis of Alzheimer’s disease.}, keywords = {}, pubstate = {published}, tppubtype = {mastersthesis} } Alzheimer’s Disease is a chronic neurodegenerative disease with high economic and social impact, being the major source of dementia worldwide. It is responsible for a progressive memory loss and other changes at behavior and motor level, essentially originated by Aβ and tau proteins accumulation in brain’s tissues. The ineffectiveness of actual diagnostic methods in early disease detection and the limitations in therapy approaches, demands finding non-invasive molecular biomarker with high sensitivity and specificity, for use in early diagnosis, evaluation of disease progression and therapeutic application, as well as the design of new analytical devices that may be used routinely in clinical context. MiRNAs are non-coding RNAs responsible for post-transcriptional genetic regulation, playing an important role in several biological processes, including neuronal related activities. miRNAs arise today as emerging potential Alzheimer biomarkers, highlighting miRNa-107 that is early reduced at patient’s brains and responsible for regulation of several molecules directly involved in Alzheimer’s pathology. On the other hand, electrochemical biosensors are a promising technology for miRNA detection and quantification, providing fast responses with low cost and simple procedures, associated to high sensitivity and specificity. Thus, this work focused (1) in the production of a three electrode system disposable, homemade, and carbon screen printed electrodes (C-SPEs) for biosensor’s use and (2) in the development of a biosensor for miRNA-107, based on its hybridization with a complementary probe and subsequent electrochemical detection, with potential application in a POC device for diagnosis of Alzheimer’s disease. |
C Ribeiro Development of a molecular imprinting polymer for potentiometric detection of an Alzheimer’s biomarker (Masters Thesis) Supervision: FTC Moreira, R Fernandes, MGF Sales. Escola Superior de Tecnologia da Saúde do Porto, 2016. @mastersthesis{Ribeiro2016, title = {Development of a molecular imprinting polymer for potentiometric detection of an Alzheimer’s biomarker}, author = {C Ribeiro}, year = {2016}, date = {2016-11-29}, school = {Supervision: FTC Moreira, R Fernandes, MGF Sales. Escola Superior de Tecnologia da Saúde do Porto}, abstract = {This research presents the development of a new sensor device for the diagnosis of Alzheimer Diseases (AD) in point-of-care, made with new synthetic biomimetic materials that were incorporated in plasticized poly(vinyl chloride), PVC, membranes, for subsequent potentiometric detection. This concept was applied to target a conventional biomarker in Alzheimer diagnosis: β-Amyloid 42 (Aβ-42). The biomimetic material was designed by attaching the peptide Aβ-42 (0.01 μg/mL) to a surface of carbon nanotubes, and filling the vacant spaces by polymerizing acrylamide 5.0×10-4 mol/L (monomer), N,N′-methylenebisacrylamide 1.0×10-4 mol/L (cross-linker) and ammonium persulphate (initiator), under mild conditions. The template was removed by protheolitic action of an enzyme (Proteinase K). The stereochemical recognition of Aβ-42 of this material was confirmed by the non-rebinding ability displayed by non-imprinted (NIP) materials, obtained by imprinting without a template. The biomimetic material was employed in the construction of potentiometric sensors and tested with regard to its affinity and selectivity for binding Aβ-42, by checking the analytical performance of the obtained electrodes. For this purpose, the biomimetic material was dispersed in plasticized PVC membranes, including or not a lipophilic ionic additive, and applied on a solid conductive support made of graphite. The morphological analysis of materials was evaluated by RAMAN and Fourier Transform Infrared (FTIR) spectroscopies. The analytical behaviour of the devices was evaluated first in buffer and later in human serum. The best analytical performance in buffer was obtained with membranes including biomimetic material and lipophilic cationic additive, tetra-n-octylammonium bromide. The average limit of detection was 0.72 µg/mL and the slope was +59.04 mV/decade. The biosensor was successfully applied to the preliminary analysis of human serum samples}, keywords = {}, pubstate = {published}, tppubtype = {mastersthesis} } This research presents the development of a new sensor device for the diagnosis of Alzheimer Diseases (AD) in point-of-care, made with new synthetic biomimetic materials that were incorporated in plasticized poly(vinyl chloride), PVC, membranes, for subsequent potentiometric detection. This concept was applied to target a conventional biomarker in Alzheimer diagnosis: β-Amyloid 42 (Aβ-42). The biomimetic material was designed by attaching the peptide Aβ-42 (0.01 μg/mL) to a surface of carbon nanotubes, and filling the vacant spaces by polymerizing acrylamide 5.0×10-4 mol/L (monomer), N,N′-methylenebisacrylamide 1.0×10-4 mol/L (cross-linker) and ammonium persulphate (initiator), under mild conditions. The template was removed by protheolitic action of an enzyme (Proteinase K). The stereochemical recognition of Aβ-42 of this material was confirmed by the non-rebinding ability displayed by non-imprinted (NIP) materials, obtained by imprinting without a template. The biomimetic material was employed in the construction of potentiometric sensors and tested with regard to its affinity and selectivity for binding Aβ-42, by checking the analytical performance of the obtained electrodes. For this purpose, the biomimetic material was dispersed in plasticized PVC membranes, including or not a lipophilic ionic additive, and applied on a solid conductive support made of graphite. The morphological analysis of materials was evaluated by RAMAN and Fourier Transform Infrared (FTIR) spectroscopies. The analytical behaviour of the devices was evaluated first in buffer and later in human serum. The best analytical performance in buffer was obtained with membranes including biomimetic material and lipophilic cationic additive, tetra-n-octylammonium bromide. The average limit of detection was 0.72 µg/mL and the slope was +59.04 mV/decade. The biosensor was successfully applied to the preliminary analysis of human serum samples |
R Torre Production of biomimetic materials for photovoltaic cells (Masters Thesis) Supervision: FTC Moreira, MGF Sales. Instituto Superior de Engenharia do Porto, 2016. @mastersthesis{Torre2016, title = {Production of biomimetic materials for photovoltaic cells}, author = {R Torre}, year = {2016}, date = {2016-11-22}, school = {Supervision: FTC Moreira, MGF Sales. Instituto Superior de Engenharia do Porto}, abstract = {Carcinoembryonic antigen (CEA) is a glycoprotein produced by cells which are in contact with the gastrointestinal tract of the foetus. CEA is also found in adults, but in small quantities. High concentrations of this protein in the blood, may therefore signal gastrointestinal tract complications, such as colorectal cancer. In this regard, it is important to create new devices or methods for tracking this biomarker, in order to, detect colorectal cancer in its early stages. Moreover, the search for new materials that confer higher selectivity and sensitivity to the detection systems are also crucial elements for sustaining clinical medical decisions. In this study, an electrochemical CEA sensor was developed by assembling directly on a conductive transparent glass a sensing material prepared by molecular imprinting polymer (MIP) technology. The behaviour of the sensing layer in the presence of the protein was evaluated by several electrochemical techniques, such as, cyclic voltammetry and impedance spectroscopy. Several parameters regarding the polymerization of pyrrole have been optimized, namely solution concentration, potential range and scan-rate. A Non-imprinting polymer (NIP) material was also prepared as control, in the same form as MIP but in the absence of protein. Some procedures were made having in mind that the sensor would be included in a dye sensitized solar cell (DSCC). The biosensor was calibrated by consecutive incubation in increasing concentrations of CEA. The calibration curve displayed a linear behavior from 5.0x10-6 a 5.0x10-1 ug/mL. The obtained results revealed a good precision (standard deviation of 13%) and a limit of detection of 0.935 ng/mL. The device displayed however limited behavior in the presence of iodide, for which its application to DSSCs requires additional studies. Keys: Carcinoembryonic Antigen, Electrochemical, Molecular Imprinting, Cancer Biomarkers.}, keywords = {}, pubstate = {published}, tppubtype = {mastersthesis} } Carcinoembryonic antigen (CEA) is a glycoprotein produced by cells which are in contact with the gastrointestinal tract of the foetus. CEA is also found in adults, but in small quantities. High concentrations of this protein in the blood, may therefore signal gastrointestinal tract complications, such as colorectal cancer. In this regard, it is important to create new devices or methods for tracking this biomarker, in order to, detect colorectal cancer in its early stages. Moreover, the search for new materials that confer higher selectivity and sensitivity to the detection systems are also crucial elements for sustaining clinical medical decisions. In this study, an electrochemical CEA sensor was developed by assembling directly on a conductive transparent glass a sensing material prepared by molecular imprinting polymer (MIP) technology. The behaviour of the sensing layer in the presence of the protein was evaluated by several electrochemical techniques, such as, cyclic voltammetry and impedance spectroscopy. Several parameters regarding the polymerization of pyrrole have been optimized, namely solution concentration, potential range and scan-rate. A Non-imprinting polymer (NIP) material was also prepared as control, in the same form as MIP but in the absence of protein. Some procedures were made having in mind that the sensor would be included in a dye sensitized solar cell (DSCC). The biosensor was calibrated by consecutive incubation in increasing concentrations of CEA. The calibration curve displayed a linear behavior from 5.0x10-6 a 5.0x10-1 ug/mL. The obtained results revealed a good precision (standard deviation of 13%) and a limit of detection of 0.935 ng/mL. The device displayed however limited behavior in the presence of iodide, for which its application to DSSCs requires additional studies. Keys: Carcinoembryonic Antigen, Electrochemical, Molecular Imprinting, Cancer Biomarkers. |
L Gonçalves Development of a biosensor for rapid diagnosis of Alzheimer’s disease (Masters Thesis) Supervision: FTC Moreira, MGF Sales. Instituto Superior de Engenharia do Porto, 2016. @mastersthesis{Gonçalves2016, title = {Development of a biosensor for rapid diagnosis of Alzheimer’s disease}, author = {L Gonçalves}, year = {2016}, date = {2016-11-22}, school = {Supervision: FTC Moreira, MGF Sales. Instituto Superior de Engenharia do Porto}, abstract = {The need to develop fast and cheap methods accessible to everyone around the world is extremely important, especially when it comes to improve global health conditions. A crucial factor for the prevention and treatment of diseases is their correct diagnosis. Biosensors are a promising tool that can prove to be very useful in point-of-care testing, also offering easy construction procedures and biocompatibility, at a low cost. The objective of this work is to develop an electrochemical biosensor for screening Alzheimer's disease. It is based on the detection of a biomarker associated with the neuro inflammation processes, Interleukin 6 (IL-6). The devices described herein are based on printed carbon electrodes on a ceramic support, using screen-printing technique. The electrical circuits are designed by a conductive graphite ink and printed later on the working electrode for the development of molecular imprinting polymer. The mixture consists on the analyte (IL-6), the monomer (Pyrrol), a crosslinking agent and a radical initiator. The modification of the surface of the electrode occurred by electrochemical polymerization, forming a conductive polymer in the matrix. The electropolymerization parameters where optimized prior to polymerization. The protein was imprinted on the sensing layer by growing the polymer around IL-6 and removing it later by proteolytic action of a suitable acid. The performance of the biosensor was evaluated by electroanalytical techniques. The chemical and morphological characterization of the materials was carried by Raman analysis. The biosensor response was observed from 0.02 pg/mL to 2.0 μg/mL from IL-6, indicating that the response limits are within the desired physiological parameters, since for a healthy individual the value is around 1.6 pg/mL and for an individual with neuro-inflammation is 2.3 pg/mL. Overall, the presented biosensor offers the advantages of being a low cost and reproducible biosensor, with low detection limits and fast response.}, keywords = {}, pubstate = {published}, tppubtype = {mastersthesis} } The need to develop fast and cheap methods accessible to everyone around the world is extremely important, especially when it comes to improve global health conditions. A crucial factor for the prevention and treatment of diseases is their correct diagnosis. Biosensors are a promising tool that can prove to be very useful in point-of-care testing, also offering easy construction procedures and biocompatibility, at a low cost. The objective of this work is to develop an electrochemical biosensor for screening Alzheimer's disease. It is based on the detection of a biomarker associated with the neuro inflammation processes, Interleukin 6 (IL-6). The devices described herein are based on printed carbon electrodes on a ceramic support, using screen-printing technique. The electrical circuits are designed by a conductive graphite ink and printed later on the working electrode for the development of molecular imprinting polymer. The mixture consists on the analyte (IL-6), the monomer (Pyrrol), a crosslinking agent and a radical initiator. The modification of the surface of the electrode occurred by electrochemical polymerization, forming a conductive polymer in the matrix. The electropolymerization parameters where optimized prior to polymerization. The protein was imprinted on the sensing layer by growing the polymer around IL-6 and removing it later by proteolytic action of a suitable acid. The performance of the biosensor was evaluated by electroanalytical techniques. The chemical and morphological characterization of the materials was carried by Raman analysis. The biosensor response was observed from 0.02 pg/mL to 2.0 μg/mL from IL-6, indicating that the response limits are within the desired physiological parameters, since for a healthy individual the value is around 1.6 pg/mL and for an individual with neuro-inflammation is 2.3 pg/mL. Overall, the presented biosensor offers the advantages of being a low cost and reproducible biosensor, with low detection limits and fast response. |
AIFL Silva Development of a color test sensor for drug detection in aquatic environment - application to chlorotetracycline (Masters Thesis) Supervision: HIAS Gomes, MGF Sales. Faculdade de Nutrição da Universidade do Porto, 2016. @mastersthesis{Silva2016b, title = {Development of a color test sensor for drug detection in aquatic environment - application to chlorotetracycline}, author = {AIFL Silva }, year = {2016}, date = {2016-10-12}, school = {Supervision: HIAS Gomes, MGF Sales. Faculdade de Nutrição da Universidade do Porto}, abstract = {While fish products consumption is growing, mainly because it is considered to be healthy, the capture of wild fish is not sufficient to comply with human’s needs in this regard. Viable economic and environmental measures include aquaculture, which is currently one of the fastest growing food-production sectors. However, intensive farming of fish inside small tanks has led to the appearance of diseases that need drug control. In this context, antibiotics are commonly used is aquaculture, posing increased concerns in public health, including fish consumers in food service units. The main goal of this work was to develop a sensor for drug detection in aquatic environment and/or food, using a low-cost material never tested before that would allow implementing on-site sample analysis. The material selected for this purpose was a material derived from cellulose. This material was sensitized to an antibiotic by binding to it a metal species that can change color in the presence of the drug; the color intensity may also be related to the antibiotic concentration. As proof-of-concept, chlortetracycline was selected as target antibiotic, which is among the most frequently used antibiotics in aquaculture. The material modification was made by self-assembling an amine monolayer, to which metallic species may complex. These modifications were followed by Fourier Transform Infrared Spectroscopy (FTIR) equipped with an Attenuated Total Reflectance (ATR) accessory and optimized by comparing the color intensity/variations observed by naked eye or by a digital image collected by a camera. A linear correlation was further established, between the color coordinates and the antibiotic concentration. The sensory materials were applied to the analysis of aquarium water and food samples (aquaculture trout and aviary chicken). Overall, this work provided a simple and effective procedure, using a lowcost material, for on-site chlortetracycline detection in water and food. The modified swab is dipped into the sample for a given time and its color compared to a color gradient generated by standard solutions.}, keywords = {}, pubstate = {published}, tppubtype = {mastersthesis} } While fish products consumption is growing, mainly because it is considered to be healthy, the capture of wild fish is not sufficient to comply with human’s needs in this regard. Viable economic and environmental measures include aquaculture, which is currently one of the fastest growing food-production sectors. However, intensive farming of fish inside small tanks has led to the appearance of diseases that need drug control. In this context, antibiotics are commonly used is aquaculture, posing increased concerns in public health, including fish consumers in food service units. The main goal of this work was to develop a sensor for drug detection in aquatic environment and/or food, using a low-cost material never tested before that would allow implementing on-site sample analysis. The material selected for this purpose was a material derived from cellulose. This material was sensitized to an antibiotic by binding to it a metal species that can change color in the presence of the drug; the color intensity may also be related to the antibiotic concentration. As proof-of-concept, chlortetracycline was selected as target antibiotic, which is among the most frequently used antibiotics in aquaculture. The material modification was made by self-assembling an amine monolayer, to which metallic species may complex. These modifications were followed by Fourier Transform Infrared Spectroscopy (FTIR) equipped with an Attenuated Total Reflectance (ATR) accessory and optimized by comparing the color intensity/variations observed by naked eye or by a digital image collected by a camera. A linear correlation was further established, between the color coordinates and the antibiotic concentration. The sensory materials were applied to the analysis of aquarium water and food samples (aquaculture trout and aviary chicken). Overall, this work provided a simple and effective procedure, using a lowcost material, for on-site chlortetracycline detection in water and food. The modified swab is dipped into the sample for a given time and its color compared to a color gradient generated by standard solutions. |
2015
AR Cardoso Development of an electrochemical biosensor for the detection of miRNA-155 in breast cancer (Masters Thesis) Supervision: FTC Moreira, R Fernandes, MGF Sales. Escola Superior de Tecnologia da Saúde do Porto, 2015. @mastersthesis{Cardoso2015, title = {Development of an electrochemical biosensor for the detection of miRNA-155 in breast cancer}, author = {AR Cardoso}, url = {http://hdl.handle.net/10400.22/8488}, year = {2015}, date = {2015-12-22}, school = {Supervision: FTC Moreira, R Fernandes, MGF Sales. Escola Superior de Tecnologia da Saúde do Porto}, abstract = {Breast cancer is one of the most prevalent forms of cancer in women. Despite all recent advances in early diagnosis and therapy, mortality data is not decreasing. This is an outcome of the inexistence of validated serum biomarkers allowing an early prognosis, out coming from the limited understanding of the natural history of the disease. In this context, miRNAs have been attracting a special interest throughout the scientific community as promising biomarkers in the early diagnosis of cancer. In breast cancer, several miRNAs and their levels of expression are significantly different between normal tissue and tissue with neoplasia, as well as between different molecular subtypes of breast cancer, also associated with prognosis. Thus, this thesis presents a meta-analysis that allows identifying a reliable miRNA biomarker for the early detection of breast cancer. In this, miRNA-155 was identified as the best one and an electrochemical biosensor was developed for its detection in serum samples. The biosensor was assembled by following three button-up stages: (1) the complementary miRNA sequence thiol terminated (anti-miRNA- 155) was immobilized on a commercial gold screen-printed electrode (Au-SPE), followed by (2) blocking non-specific binding with mercaptosuccinic acid and by (3) miRNA hybridization. The biosensor was able to detect miRNA concentrations lying in the 10 -18 mol/L (aM) range, displaying a linear response from 10 aM to 1nM. The device showed a limit of detection of 5.7 aM in human serum samples and good selectivity against other biomolecules in serum, such as cancer antigen CA-15.3 and bovine serum albumin (BSA). Overall, this simple and sensitive strategy is a promising approach for the quantitative and/or simultaneous analysis of multiple miRNA in physiological fluids, aiming at further biomedical research devoted to biomarker monitoring and point-of- care diagnosis.}, keywords = {}, pubstate = {published}, tppubtype = {mastersthesis} } Breast cancer is one of the most prevalent forms of cancer in women. Despite all recent advances in early diagnosis and therapy, mortality data is not decreasing. This is an outcome of the inexistence of validated serum biomarkers allowing an early prognosis, out coming from the limited understanding of the natural history of the disease. In this context, miRNAs have been attracting a special interest throughout the scientific community as promising biomarkers in the early diagnosis of cancer. In breast cancer, several miRNAs and their levels of expression are significantly different between normal tissue and tissue with neoplasia, as well as between different molecular subtypes of breast cancer, also associated with prognosis. Thus, this thesis presents a meta-analysis that allows identifying a reliable miRNA biomarker for the early detection of breast cancer. In this, miRNA-155 was identified as the best one and an electrochemical biosensor was developed for its detection in serum samples. The biosensor was assembled by following three button-up stages: (1) the complementary miRNA sequence thiol terminated (anti-miRNA- 155) was immobilized on a commercial gold screen-printed electrode (Au-SPE), followed by (2) blocking non-specific binding with mercaptosuccinic acid and by (3) miRNA hybridization. The biosensor was able to detect miRNA concentrations lying in the 10 -18 mol/L (aM) range, displaying a linear response from 10 aM to 1nM. The device showed a limit of detection of 5.7 aM in human serum samples and good selectivity against other biomolecules in serum, such as cancer antigen CA-15.3 and bovine serum albumin (BSA). Overall, this simple and sensitive strategy is a promising approach for the quantitative and/or simultaneous analysis of multiple miRNA in physiological fluids, aiming at further biomedical research devoted to biomarker monitoring and point-of- care diagnosis. |
JDL Alves Materials and sensor devices for Norfloxacin detection (Masters Thesis) Supervision: LAANA Truta, MGF Sales. Instituto Superior de Engenharia do Porto, 2015. @mastersthesis{Alves2015, title = {Materials and sensor devices for Norfloxacin detection}, author = {JDL Alves}, url = {http://hdl.handle.net/10400.22/8093}, year = {2015}, date = {2015-11-30}, school = {Supervision: LAANA Truta, MGF Sales. Instituto Superior de Engenharia do Porto}, abstract = {The proposed work concerns the development and characterization of potentiometric sensors based on MIPs for the determination of NOR, in aquaculture. The simplicity, low cost, rapidity and reversible interaction of potentiometric sensors with the analytes led to choose this type of sensor. The sensor material was obtained by molecular imprinting technology based on bulk polymerization, wherein the NOR was the template molecule. The selected monomers were pyrrole, with or without 3-aminopropyl functionalized silica gel particles. NIP materials were also produced, by excluding the template from the procedure. The characterization of surface morphology of these sensor materials was obtained by Scanning Electron Microscopy (SEM) and Fourier Transform Infrared Spectroscopy (FTIR) analysis. The biomimetic sensors were included in polymer membranes and, after, incorporated in electrode bodies. The evaluation performance of the electrodes was made using calibration curves for different buffers. All assays and analysis performed have allowed to conclude that the pyrrol MIP with anionic additive (MPyAdA) was the biomimetic sensor with the best analytical features, in HEPES, pH 5.70. Under this condition, the limit of detection was 2.82x10-6 mol/L, for a linear response after 2.96x10-6 mol/L, with a cationic slope of 54.1 mV/decade. The application of the biomimetic sensors in spiked environmental water has also been conducted successfully.}, keywords = {}, pubstate = {published}, tppubtype = {mastersthesis} } The proposed work concerns the development and characterization of potentiometric sensors based on MIPs for the determination of NOR, in aquaculture. The simplicity, low cost, rapidity and reversible interaction of potentiometric sensors with the analytes led to choose this type of sensor. The sensor material was obtained by molecular imprinting technology based on bulk polymerization, wherein the NOR was the template molecule. The selected monomers were pyrrole, with or without 3-aminopropyl functionalized silica gel particles. NIP materials were also produced, by excluding the template from the procedure. The characterization of surface morphology of these sensor materials was obtained by Scanning Electron Microscopy (SEM) and Fourier Transform Infrared Spectroscopy (FTIR) analysis. The biomimetic sensors were included in polymer membranes and, after, incorporated in electrode bodies. The evaluation performance of the electrodes was made using calibration curves for different buffers. All assays and analysis performed have allowed to conclude that the pyrrol MIP with anionic additive (MPyAdA) was the biomimetic sensor with the best analytical features, in HEPES, pH 5.70. Under this condition, the limit of detection was 2.82x10-6 mol/L, for a linear response after 2.96x10-6 mol/L, with a cationic slope of 54.1 mV/decade. The application of the biomimetic sensors in spiked environmental water has also been conducted successfully. |
AM Gomes Development of a biosensor for glutamic acid (Masters Thesis) Supervision: APM Tavares, MGF Sales. Instituto Superior de Engenharia do Porto, 2015. @mastersthesis{Gomes2015b, title = {Development of a biosensor for glutamic acid}, author = {AM Gomes}, url = {http://recipp.ipp.pt/handle/10400.22/8005 http://hdl.handle.net/10400.22/8005}, year = {2015}, date = {2015-11-30}, school = {Supervision: APM Tavares, MGF Sales. Instituto Superior de Engenharia do Porto}, abstract = {The aim of this work is the development of biosensor based on molecularly imprinted polymer for detecting a target molecule, glutamic acid that is converted into glutamine by glutamine synthetase, using potentiometry. In neoplastic cells glutamine isn’t synthesized so glutamic acid can be considered a potential anticancer agent. The molecular imprinting technique used was the polymerization in bulk by combining acrylamide and bis acrylamide with glutamic acid. To verify that the potentiometric response obtained was indeed the target molecule were prepared in parallel with the sensors, control materials, with non molecular imprinting polymers (NIP). To control the chemical constitution of the various sensors, NIP and the molecularly imprinted polymer (MIP) before and after remotion of the molecule were performed by spectroscopy studies of Fourier Transform Infrared (FTIR), Scanning Electron Microscope ( SEM) and Spectroscopy and X-Ray energy dispersive (EDS). The developed materials have been applied in various membranes differing from each other with the selective ion. A review of the general characteristics of the membranes was based on an analysis of the calibration curves obtained in media with different pH values, by comparing the various electrodes. The pH 5 showed the best result associated to a membrane containing an additive, p-tetra-octilphenol, and the sensor percentage of 3%. It was tested in biological material, urine, with the best characteristics in terms of sensitivity (± 18,32mV / decade) in terms of linearity (1,6x10-6 to 1,48x10-3 moles / L) . It was also found that by applying interfering ions in solution, they do not interfere with this and may be applied to the sample without changing the potentiometric response. The probe is capable of distinguishing the rest of glutamic acid ions present in the solution.}, keywords = {}, pubstate = {published}, tppubtype = {mastersthesis} } The aim of this work is the development of biosensor based on molecularly imprinted polymer for detecting a target molecule, glutamic acid that is converted into glutamine by glutamine synthetase, using potentiometry. In neoplastic cells glutamine isn’t synthesized so glutamic acid can be considered a potential anticancer agent. The molecular imprinting technique used was the polymerization in bulk by combining acrylamide and bis acrylamide with glutamic acid. To verify that the potentiometric response obtained was indeed the target molecule were prepared in parallel with the sensors, control materials, with non molecular imprinting polymers (NIP). To control the chemical constitution of the various sensors, NIP and the molecularly imprinted polymer (MIP) before and after remotion of the molecule were performed by spectroscopy studies of Fourier Transform Infrared (FTIR), Scanning Electron Microscope ( SEM) and Spectroscopy and X-Ray energy dispersive (EDS). The developed materials have been applied in various membranes differing from each other with the selective ion. A review of the general characteristics of the membranes was based on an analysis of the calibration curves obtained in media with different pH values, by comparing the various electrodes. The pH 5 showed the best result associated to a membrane containing an additive, p-tetra-octilphenol, and the sensor percentage of 3%. It was tested in biological material, urine, with the best characteristics in terms of sensitivity (± 18,32mV / decade) in terms of linearity (1,6x10-6 to 1,48x10-3 moles / L) . It was also found that by applying interfering ions in solution, they do not interfere with this and may be applied to the sample without changing the potentiometric response. The probe is capable of distinguishing the rest of glutamic acid ions present in the solution. |
2014
ART Santos Development of a biosensor for a biomarker in breast cancer (Masters Thesis) Supervision: FTC Moreira, MGF Sales, Universidade de Aveiro, 2014. @mastersthesis{Santos2014, title = {Development of a biosensor for a biomarker in breast cancer}, author = {ART Santos}, url = {http://biblioteca.versila.com/2770275 http://p3.publico.pt/actualidade/educacao/16942/future-ideas-portugueses-vencem-tres-dos-seis-dos-premios}, year = {2014}, date = {2014-12-17}, school = {Supervision: FTC Moreira, MGF Sales, Universidade de Aveiro}, abstract = {A presente dissertação apresenta o desenvolvimento de um dispositivo dedicado ao diagnóstico do cancro da mama em point-of-care e que foi construído com base na preparação de um novo material biomimético e sua incorporação em membranas poliméricas de poli(cloreto de vinilo), PVC, plastificado, para subsequente deteção potenciométrica. Foi considerado para este estudo o biomarcador de interesse clínico convencional no contexto do cancro da mama, o Breast Cancer Antigen (CA15-3). O desenho do novo material biossensor baseou-se na síntese de anticorpos plásticos por tecnologia de impressão molecular. O anticorpo plástico foi impresso por polimerização em volta da estrutura proteica do CA15-3, atuando este biomarcador como obstáculo ao crescimento da matriz polimérica. O polímero impresso foi obtido por eletropolimerização de pirrol, estabelecida na superfície de vidro condutor (com FTO) com base em voltametria cíclica, que compreendeu 40 ciclos entre -0,2 e 1,0 V. A mistura reacional utilizada continha monómero (pirrol, 5,0×10-3 mol/L) e proteína molde (CA15-3, 100U/mL), preparados em solução de tampão fosfato salino, com pH 7,2 e com 1% de etilenoglicol. O biomarcador foi removido da matriz polimérica por ação proteolítica da proteinase K. O material biomimético preparado foi aplicado na construção de sensores potenciométricos e testado relativamente à sua afinidade e seletividade de ligação à CA15-3, por avaliação do desempenho analítico dos elétrodos resultantes. Para este efeito, o material biomimético foi disperso em membranas de PVC plastificado, que continham ou não um aditivo iónico lipofílico, e aplicado em suporte condutor sólido. O desempenho analítico foi avaliado inicialmente em meio tampão e posteriormente em soro sintético. As melhores características de resposta analítica em soro sintético foram obtidas com membranas preparadas com material impresso e com aditivo aniónico lipofílico, tetrakis-4-(Clorofenil)borato. Os limites de deteção correspondentes foram, em média, 4,6 U/mL de CEA, para uma resposta linear a partir de 5,4 U/mL e uma sensibilidade catiónica igual a 60,6 mV/década. As análises de soro sintético dopado indicaram resultados exatos e precisos.}, keywords = {}, pubstate = {published}, tppubtype = {mastersthesis} } A presente dissertação apresenta o desenvolvimento de um dispositivo dedicado ao diagnóstico do cancro da mama em point-of-care e que foi construído com base na preparação de um novo material biomimético e sua incorporação em membranas poliméricas de poli(cloreto de vinilo), PVC, plastificado, para subsequente deteção potenciométrica. Foi considerado para este estudo o biomarcador de interesse clínico convencional no contexto do cancro da mama, o Breast Cancer Antigen (CA15-3). O desenho do novo material biossensor baseou-se na síntese de anticorpos plásticos por tecnologia de impressão molecular. O anticorpo plástico foi impresso por polimerização em volta da estrutura proteica do CA15-3, atuando este biomarcador como obstáculo ao crescimento da matriz polimérica. O polímero impresso foi obtido por eletropolimerização de pirrol, estabelecida na superfície de vidro condutor (com FTO) com base em voltametria cíclica, que compreendeu 40 ciclos entre -0,2 e 1,0 V. A mistura reacional utilizada continha monómero (pirrol, 5,0×10-3 mol/L) e proteína molde (CA15-3, 100U/mL), preparados em solução de tampão fosfato salino, com pH 7,2 e com 1% de etilenoglicol. O biomarcador foi removido da matriz polimérica por ação proteolítica da proteinase K. O material biomimético preparado foi aplicado na construção de sensores potenciométricos e testado relativamente à sua afinidade e seletividade de ligação à CA15-3, por avaliação do desempenho analítico dos elétrodos resultantes. Para este efeito, o material biomimético foi disperso em membranas de PVC plastificado, que continham ou não um aditivo iónico lipofílico, e aplicado em suporte condutor sólido. O desempenho analítico foi avaliado inicialmente em meio tampão e posteriormente em soro sintético. As melhores características de resposta analítica em soro sintético foram obtidas com membranas preparadas com material impresso e com aditivo aniónico lipofílico, tetrakis-4-(Clorofenil)borato. Os limites de deteção correspondentes foram, em média, 4,6 U/mL de CEA, para uma resposta linear a partir de 5,4 U/mL e uma sensibilidade catiónica igual a 60,6 mV/década. As análises de soro sintético dopado indicaram resultados exatos e precisos. |
AS Sacramento Development of a biosensor to monitor acetylcholine, for a biomarker associated with Alzheimer’s disease (Masters Thesis) Supervision: FTC Moreira, MGF Sales. Instituto Superior de Engenharia do Porto, 2014. @mastersthesis{Sacramento2014, title = {Development of a biosensor to monitor acetylcholine, for a biomarker associated with Alzheimer’s disease}, author = {AS Sacramento}, url = {http://hdl.handle.net/10400.22/8433}, year = {2014}, date = {2014-11-19}, school = {Supervision: FTC Moreira, MGF Sales. Instituto Superior de Engenharia do Porto}, abstract = {The main goal of this thesis was to develop and characterize potentiometric sensors, based on molecularly imprinted polymers (MIP), for the determination of Acetylcholine (ACh). Acetylcholine is a neurotransmitter associated with Alzheimer's disease. The biomimetic materials assembled to interact with ACh were obtained by Bulk Polymerization, combing Carbon Nanotubes with monomers of Aniline dispersed in PVC that was plasticized with oNFOE. To measure the effect of the imprinted sites on the response of the MIP materials, non-imprinted materials (NIP) were prepared and evaluated as control materials. The chemical characterization of these materials was made by means of Raman Spectroscopy and Fourier Transformed Infrared Spectroscopy (FTIR). The developed materials were fed into ion-selective membranes, prepared with or without lipophilic ionic additive, of positive or negative charge. The evaluation of the membranes in terms of Ach recognition was made by comparing the characteristics of the various electrodes. These characteristics were obtained from calibration curves, made in pH conditions. The best analytical performance was found in acid medium, specifically pH 4, with membranes containing MIP material and anionic additive, showing a sensitivity of + 83,86 mV decade -1 from 3,52×10 -5 to 1,73×10 -3 M. The best selectivity behavior was found for membranes with an anionic additive, showing lower values of log K POT . The least interfering species was creatine and the most interfering one was creatinine. The electrodes were also applied to the analysis of synthetic serum samples. The quality of the obtained results was linked to the concentration level of ACh in the sample, and it was possible to identify a concentration range where results were accurate and precise. In general, the biosensors containing MIP and anionic additive showed a suitable behavior to extend this study to real samples.}, keywords = {}, pubstate = {published}, tppubtype = {mastersthesis} } The main goal of this thesis was to develop and characterize potentiometric sensors, based on molecularly imprinted polymers (MIP), for the determination of Acetylcholine (ACh). Acetylcholine is a neurotransmitter associated with Alzheimer's disease. The biomimetic materials assembled to interact with ACh were obtained by Bulk Polymerization, combing Carbon Nanotubes with monomers of Aniline dispersed in PVC that was plasticized with oNFOE. To measure the effect of the imprinted sites on the response of the MIP materials, non-imprinted materials (NIP) were prepared and evaluated as control materials. The chemical characterization of these materials was made by means of Raman Spectroscopy and Fourier Transformed Infrared Spectroscopy (FTIR). The developed materials were fed into ion-selective membranes, prepared with or without lipophilic ionic additive, of positive or negative charge. The evaluation of the membranes in terms of Ach recognition was made by comparing the characteristics of the various electrodes. These characteristics were obtained from calibration curves, made in pH conditions. The best analytical performance was found in acid medium, specifically pH 4, with membranes containing MIP material and anionic additive, showing a sensitivity of + 83,86 mV decade -1 from 3,52×10 -5 to 1,73×10 -3 M. The best selectivity behavior was found for membranes with an anionic additive, showing lower values of log K POT . The least interfering species was creatine and the most interfering one was creatinine. The electrodes were also applied to the analysis of synthetic serum samples. The quality of the obtained results was linked to the concentration level of ACh in the sample, and it was possible to identify a concentration range where results were accurate and precise. In general, the biosensors containing MIP and anionic additive showed a suitable behavior to extend this study to real samples. |
CAC Campos Development of plastic antibodies for a cancer biomarker (Masters Thesis) Supervision: LAANA Truta, MGF Sales. Instituto Superior de Engenharia do Porto, 2014. @mastersthesis{Campos2014, title = {Development of plastic antibodies for a cancer biomarker}, author = {CAC Campos}, url = {http://hdl.handle.net/10400.22/6023}, year = {2014}, date = {2014-11-19}, school = {Supervision: LAANA Truta, MGF Sales. Instituto Superior de Engenharia do Porto}, abstract = {The proposed work concerns the development of a new plastic antibody (also known as Molecularly Imprinted Polymer, MIP) for carcinoembryonic antigen (CEA) and its application in the construction of portable, low-cost and small size potentiometric devices, to monitor this biomarker of colorectal cancer in point-of-care context. The plastic antibody was obtained by molecularly-oriented imprinting technology, making use of electropolymerization over a conductive glass surface (FTO glass). In brief, this was done by electropolymerizing aniline over the conductive glass and adsorbing CEA to this surface, surrounded or not by positively charged monomers (vinylbenzyltrimethylammonium chloride, VB). This was followed by subsequent electropolymerization of o-phenylenediamine (oPD) monomer, after which CEA was removed by proteolytic action of trypsin. The effectiveness of the imprinting process of CEA over the polymeric material was controlled by preparing a similar material, named non-imprinted polymer (NIP), where protein and VB were omitted. The obtained materials were chemically characterized by Fourier transform infrared spectroscopy (FTIR) and confocal Raman spectroscopy. The obtained materials were used to prepare biomimetic sensors for CEA, by including these within plasticized poly(vinyl chloride) (PVC) selective membranes. The sensors were evaluated in different conditions (pH and composition). Good analytical performance was obtained under 4-(2-Hydroxyethyl)piperazine-1-ethanesulfonic acid (HEPES) buffer of pH 4.4, having selective membranes composed of MIP material with VB. The detection limit was <42 pg/mL, with a linear behaviour versus logarithm concentration up to 625 pg/mL, an average anionic slope of -61.9 mV/decade and a squared correlation coefficient >0.9974. The analytical behavior of the biomimetic sensors was evaluated in urine medium, because these devices were going to be applied in the determination of CEA in urine. Under this condition, the limit of detection was <38 pg/mL, for a linear behavior up to 625 μg/mL, an average slope of -38,4 mV/decade and a squared correlation coefficient >0.991. In general, the experimental application of the biomimetic sensors has produced accurate results, suggesting that the current biosensors could follow additional study to enable their practical application in real samples of diseased individuals.}, keywords = {}, pubstate = {published}, tppubtype = {mastersthesis} } The proposed work concerns the development of a new plastic antibody (also known as Molecularly Imprinted Polymer, MIP) for carcinoembryonic antigen (CEA) and its application in the construction of portable, low-cost and small size potentiometric devices, to monitor this biomarker of colorectal cancer in point-of-care context. The plastic antibody was obtained by molecularly-oriented imprinting technology, making use of electropolymerization over a conductive glass surface (FTO glass). In brief, this was done by electropolymerizing aniline over the conductive glass and adsorbing CEA to this surface, surrounded or not by positively charged monomers (vinylbenzyltrimethylammonium chloride, VB). This was followed by subsequent electropolymerization of o-phenylenediamine (oPD) monomer, after which CEA was removed by proteolytic action of trypsin. The effectiveness of the imprinting process of CEA over the polymeric material was controlled by preparing a similar material, named non-imprinted polymer (NIP), where protein and VB were omitted. The obtained materials were chemically characterized by Fourier transform infrared spectroscopy (FTIR) and confocal Raman spectroscopy. The obtained materials were used to prepare biomimetic sensors for CEA, by including these within plasticized poly(vinyl chloride) (PVC) selective membranes. The sensors were evaluated in different conditions (pH and composition). Good analytical performance was obtained under 4-(2-Hydroxyethyl)piperazine-1-ethanesulfonic acid (HEPES) buffer of pH 4.4, having selective membranes composed of MIP material with VB. The detection limit was <42 pg/mL, with a linear behaviour versus logarithm concentration up to 625 pg/mL, an average anionic slope of -61.9 mV/decade and a squared correlation coefficient >0.9974. The analytical behavior of the biomimetic sensors was evaluated in urine medium, because these devices were going to be applied in the determination of CEA in urine. Under this condition, the limit of detection was <38 pg/mL, for a linear behavior up to 625 μg/mL, an average slope of -38,4 mV/decade and a squared correlation coefficient >0.991. In general, the experimental application of the biomimetic sensors has produced accurate results, suggesting that the current biosensors could follow additional study to enable their practical application in real samples of diseased individuals. |
CNO Teixeira Development of colorimetric sensors towards the screening of antibiotics (Masters Thesis) Supervision: MGF Sales. Instituto Superior de Engenharia do Porto, 2014. @mastersthesis{Teixeira2014b, title = {Development of colorimetric sensors towards the screening of antibiotics}, author = {CNO Teixeira}, url = {http://hdl.handle.net/10400.22/7914}, year = {2014}, date = {2014-06-19}, school = {Supervision: MGF Sales. Instituto Superior de Engenharia do Porto}, abstract = {Increasing productivity in aquaculture systems is associated to the introduction of drugs that ensure the growth and preservation of species, but which eventually spread to the surrounding aquatic environment, promoting changes in biodiversity and entering, directly or indirectly, in the food chain . When these drugs are antimicrobial agents for human use such as amoxicillin, tetracycline or sulfonamides, there is a high risk of emergence of resistant bacterial species, something which constitutes a serious threat to public health. This introduction of antimicrobial agents on the aquatic environment through the fisheries sector can be reduced by regular or continuous monitoring of the levels of antibiotics in the water system during the implementation, as well as before discharge to the water environment. For this, analytical methods allowing high analytical frequency and continues in crops of fish tanks is necessary. The present study describes a sensor for this purpose consisting of paper chemically modified by reactions in monolayers, assuming a typical color after contact with the antibiotic. The staining intensity was related to the concentration of antibiotic The modification of the paper was based on the chemical modification of the glucose units of the paper by covalent reaction with appropriate reagents. Then created a layer of chitosan on the modified paper where the adsorbed metal species are capable of changing color in the presence of sulfadiazine paper. The resulting changes were evaluated for various parameters so as to cause a change in color due to high concentration of antibiotic. The sensors prepared were characterized from the point of view of its analytical performance, we performed the construction of a concentration range that allows getting a predictable response and crossover other antibiotics, as well as the identification of a linear relationship between concentration and color coordinates and the application of sensors in environmental water sample doped with antibiotic. Generalizing, it was possible to establish a simple modification process paper able to measure the presence and quantity of sulfadiazine.}, keywords = {}, pubstate = {published}, tppubtype = {mastersthesis} } Increasing productivity in aquaculture systems is associated to the introduction of drugs that ensure the growth and preservation of species, but which eventually spread to the surrounding aquatic environment, promoting changes in biodiversity and entering, directly or indirectly, in the food chain . When these drugs are antimicrobial agents for human use such as amoxicillin, tetracycline or sulfonamides, there is a high risk of emergence of resistant bacterial species, something which constitutes a serious threat to public health. This introduction of antimicrobial agents on the aquatic environment through the fisheries sector can be reduced by regular or continuous monitoring of the levels of antibiotics in the water system during the implementation, as well as before discharge to the water environment. For this, analytical methods allowing high analytical frequency and continues in crops of fish tanks is necessary. The present study describes a sensor for this purpose consisting of paper chemically modified by reactions in monolayers, assuming a typical color after contact with the antibiotic. The staining intensity was related to the concentration of antibiotic The modification of the paper was based on the chemical modification of the glucose units of the paper by covalent reaction with appropriate reagents. Then created a layer of chitosan on the modified paper where the adsorbed metal species are capable of changing color in the presence of sulfadiazine paper. The resulting changes were evaluated for various parameters so as to cause a change in color due to high concentration of antibiotic. The sensors prepared were characterized from the point of view of its analytical performance, we performed the construction of a concentration range that allows getting a predictable response and crossover other antibiotics, as well as the identification of a linear relationship between concentration and color coordinates and the application of sensors in environmental water sample doped with antibiotic. Generalizing, it was possible to establish a simple modification process paper able to measure the presence and quantity of sulfadiazine. |
2013
APM Tavares Monitoring parameters of interest in cardiovascular disease (Masters Thesis) Supervision: MGF Sales. Instituto Superior de Engenharia do Porto, 2013. @mastersthesis{Tavares2013b, title = {Monitoring parameters of interest in cardiovascular disease}, author = {APM Tavares}, year = {2013}, date = {2013-07-16}, school = {Supervision: MGF Sales. Instituto Superior de Engenharia do Porto}, abstract = {This work describes the preparation of Molecularly Imprinted Polymers (MIPs) acting as antibodies of synthetic nature, for the detection of Hemoglobin (Hb) and its application in small, portable and low cost devices for routine use in Point-Of- Care (POC). The imprinted polymer was created by surface imprinting technique on silica particles. Hb was first bound to the silica material and after arranged let arrange around charged monomers, 2-aminoethyl methacrylate hydrochloride (AEMH) and styrene sulfonic acid (SSA). A neutral surrounding environment was created around these by subsequent polymerization of Styrene and Divinylbenzene (DVB). Finally, the template was removed by imine cleavage after treatment with proteinase K. In order to control the efficiency of the imprinting process, a Non-Imprinted Polymer (NIP) was synthesized by the same way but without the template. The control of the effect of the charged monomers was followed by a polymer prepared similarly but without these charged monomers. All materials were used to produce potentiometric sensors and compared with regard to their affinity and selectivity for Hb by evaluating their analytical. The NIP materials were unable to change the potential values of the device in different Hb concentrations, meaning that there were specific site for Hb binding created by means of its imprinting. The stereochemical recognition of Hb was confirmed by the non-rebinding ability displayed by non-imprinted (NIM) materials, obtained by imprinting without a template. SEM analysis confirmed the surface modification of the silica beads. The biomimetic material was dispersed in plasticized PVC selective membranes and used as ionophores in potentiometric transduction of Hb. Some membranes showed a high affinity for Hb, retaining a red color in the selective membrane after calibration. The presence of Hb inside these membranes was confirmed by removing the membrane from the electrode body and proceeding with its qualitative analysis by means of Fourier transform infrared spectroscopy, optical microscopy and Raman confocal microscopy. Good features were obtained in HEPES buffer of pH 5 with membranes MMA. Under this condition, the limits of detection were 43.8μg/mL for a linear response after 83.8 μg/mL with a cationic slope of 40.4 mV/decade. The analytical application was conducted successfully and showed accurate and precise results.}, keywords = {}, pubstate = {published}, tppubtype = {mastersthesis} } This work describes the preparation of Molecularly Imprinted Polymers (MIPs) acting as antibodies of synthetic nature, for the detection of Hemoglobin (Hb) and its application in small, portable and low cost devices for routine use in Point-Of- Care (POC). The imprinted polymer was created by surface imprinting technique on silica particles. Hb was first bound to the silica material and after arranged let arrange around charged monomers, 2-aminoethyl methacrylate hydrochloride (AEMH) and styrene sulfonic acid (SSA). A neutral surrounding environment was created around these by subsequent polymerization of Styrene and Divinylbenzene (DVB). Finally, the template was removed by imine cleavage after treatment with proteinase K. In order to control the efficiency of the imprinting process, a Non-Imprinted Polymer (NIP) was synthesized by the same way but without the template. The control of the effect of the charged monomers was followed by a polymer prepared similarly but without these charged monomers. All materials were used to produce potentiometric sensors and compared with regard to their affinity and selectivity for Hb by evaluating their analytical. The NIP materials were unable to change the potential values of the device in different Hb concentrations, meaning that there were specific site for Hb binding created by means of its imprinting. The stereochemical recognition of Hb was confirmed by the non-rebinding ability displayed by non-imprinted (NIM) materials, obtained by imprinting without a template. SEM analysis confirmed the surface modification of the silica beads. The biomimetic material was dispersed in plasticized PVC selective membranes and used as ionophores in potentiometric transduction of Hb. Some membranes showed a high affinity for Hb, retaining a red color in the selective membrane after calibration. The presence of Hb inside these membranes was confirmed by removing the membrane from the electrode body and proceeding with its qualitative analysis by means of Fourier transform infrared spectroscopy, optical microscopy and Raman confocal microscopy. Good features were obtained in HEPES buffer of pH 5 with membranes MMA. Under this condition, the limits of detection were 43.8μg/mL for a linear response after 83.8 μg/mL with a cationic slope of 40.4 mV/decade. The analytical application was conducted successfully and showed accurate and precise results. |
RM Castro Development of point of care diagnostics for heart disease biomarkers (Masters Thesis) Supervision: MGF Sales. Instituto Superior de Engenharia do Porto, 2013. @mastersthesis{Castro2013, title = {Development of point of care diagnostics for heart disease biomarkers}, author = {RM Castro}, url = {http://hdl.handle.net/10400.22/6407}, year = {2013}, date = {2013-06-19}, school = {Supervision: MGF Sales. Instituto Superior de Engenharia do Porto}, abstract = {This work describes the development of a sensor material for creatinine, prepared by molecular imprinting in a polymeric structure and its application in the development of a device of potentiometric nature for the determination of creatinine in biological fluids. Creatinine is one of the most commonly used biomarkers in monitoring renal function, since it is a good indicator of glomerular filtration rate (TFG). Different biomimetic materials designed to interact with creatinine were synthesized by free radical polymerization using the monomers methacrylic acid or vinylpyridine and an appropriate cross-linking agent. In order to assess the effect of the imprinting in the response of the imprinted materials to creatinine, control non-imprinted materials were also prepared. Raman spectroscopy and Fourier transformed infrared spectroscopy were used to control the chemical composition of such materials and the extraction of the imprinted molecule from the polymeric matrix. The binding affinity between these materials and creatinine was also evaluated based on kinetic studies. All of the described materials were incorporated into selective membranes in ion-selective electrodes, prepared with or without ionic lipophilic additive, of positive or negative charge. Evaluation of the analytical features of these electrodes in different composition and pH media indicated that only membranes with imprinted materials and anionic additive were of analytical interest. The best results were obtained with buffer Piperazine-N, N′-bis(2-ethanesulfonic acid), PIPES at pH 2.8, leading to a near- Nernstian response from 1.6×10-5 mol L-1. These electrodes also showed high selectivity, indicating a preferential response to creatinine in the presence of urea, carnitine, glucose, ascorbic acid, albumin, calcium chloride, potassium chloride, sodium chloride and magnesium sulfate. The electrodes were applied successfully to the analysis of samples of synthetic urine, when the sensor materials used were based on methacrylic acid, and serum, when the sensor materials used were based on vinylpyridine.}, keywords = {}, pubstate = {published}, tppubtype = {mastersthesis} } This work describes the development of a sensor material for creatinine, prepared by molecular imprinting in a polymeric structure and its application in the development of a device of potentiometric nature for the determination of creatinine in biological fluids. Creatinine is one of the most commonly used biomarkers in monitoring renal function, since it is a good indicator of glomerular filtration rate (TFG). Different biomimetic materials designed to interact with creatinine were synthesized by free radical polymerization using the monomers methacrylic acid or vinylpyridine and an appropriate cross-linking agent. In order to assess the effect of the imprinting in the response of the imprinted materials to creatinine, control non-imprinted materials were also prepared. Raman spectroscopy and Fourier transformed infrared spectroscopy were used to control the chemical composition of such materials and the extraction of the imprinted molecule from the polymeric matrix. The binding affinity between these materials and creatinine was also evaluated based on kinetic studies. All of the described materials were incorporated into selective membranes in ion-selective electrodes, prepared with or without ionic lipophilic additive, of positive or negative charge. Evaluation of the analytical features of these electrodes in different composition and pH media indicated that only membranes with imprinted materials and anionic additive were of analytical interest. The best results were obtained with buffer Piperazine-N, N′-bis(2-ethanesulfonic acid), PIPES at pH 2.8, leading to a near- Nernstian response from 1.6×10-5 mol L-1. These electrodes also showed high selectivity, indicating a preferential response to creatinine in the presence of urea, carnitine, glucose, ascorbic acid, albumin, calcium chloride, potassium chloride, sodium chloride and magnesium sulfate. The electrodes were applied successfully to the analysis of samples of synthetic urine, when the sensor materials used were based on methacrylic acid, and serum, when the sensor materials used were based on vinylpyridine. |
2012
HIAS Gomes Fast screening for drugs in aquatic environment and cellular systems (Masters Thesis) Supervision: MGF Sales. Instituto Superior de Engenharia do Porto, 2012. @mastersthesis{Gomes2012, title = {Fast screening for drugs in aquatic environment and cellular systems}, author = {HIAS Gomes}, url = {http://hdl.handle.net/10400.22/4469}, year = {2012}, date = {2012-06-21}, school = {Supervision: MGF Sales. Instituto Superior de Engenharia do Porto}, abstract = {The wide use of antibiotics in aquaculture has led to the emergence of resistant microbial species. It should be avoided or else minimized. This minimization requires a rigorous control of the amount of drug applied, which can be only done by means of a simple, inexpensive and on-site analytical process. For this purpose, the present work describes a sensory system made with chemically modified paper, based in an analytical procedure that was close to pH monitoring by universal pH paper. The cellulose paper was modified by self-assembling monolayer technique, gaining a typical colour after contacting with the antibiotic. The colour intensity was also linked to its concentration. As prove of concept, this new concept was applied to oxytetracycline, one of the antibiotics used frequently in aquaculture activities. The paper modification was based on the chemical change of the glucose units among the paper material by covalent bonding to specific reagents. Two different approaches were taken for this purpose: one used sol-gel based reactions while the other relied on a nucleophilic addition mechanism. The paper was after modified with metallic species ensuring a colour change after contacting with oxytetracycline. These chemical changes were evaluated and optimized in order to provide an intense colour change against the concentration of antibiotic. These changes were also followed by infrared spectroscopy. The colour changes were evaluated by visual comparison and also recorded by a digital camera. The sensory materials prepared were also characterized with regard to their analytical features, namely the identification of the colour coordinates providing a linear correlation to concentration, the linear concentration range and the cross-response against other antibiotics. These materials were also applied to the analysis of a spiked environmental water. In general, this work provided a simple way to paper modification, capable of identifying and quantifying tetracycline drugs, more precisely oxytetracycline. This was a promising process for local, quick and cheap monitoring of antibiotic drugs.}, keywords = {}, pubstate = {published}, tppubtype = {mastersthesis} } The wide use of antibiotics in aquaculture has led to the emergence of resistant microbial species. It should be avoided or else minimized. This minimization requires a rigorous control of the amount of drug applied, which can be only done by means of a simple, inexpensive and on-site analytical process. For this purpose, the present work describes a sensory system made with chemically modified paper, based in an analytical procedure that was close to pH monitoring by universal pH paper. The cellulose paper was modified by self-assembling monolayer technique, gaining a typical colour after contacting with the antibiotic. The colour intensity was also linked to its concentration. As prove of concept, this new concept was applied to oxytetracycline, one of the antibiotics used frequently in aquaculture activities. The paper modification was based on the chemical change of the glucose units among the paper material by covalent bonding to specific reagents. Two different approaches were taken for this purpose: one used sol-gel based reactions while the other relied on a nucleophilic addition mechanism. The paper was after modified with metallic species ensuring a colour change after contacting with oxytetracycline. These chemical changes were evaluated and optimized in order to provide an intense colour change against the concentration of antibiotic. These changes were also followed by infrared spectroscopy. The colour changes were evaluated by visual comparison and also recorded by a digital camera. The sensory materials prepared were also characterized with regard to their analytical features, namely the identification of the colour coordinates providing a linear correlation to concentration, the linear concentration range and the cross-response against other antibiotics. These materials were also applied to the analysis of a spiked environmental water. In general, this work provided a simple way to paper modification, capable of identifying and quantifying tetracycline drugs, more precisely oxytetracycline. This was a promising process for local, quick and cheap monitoring of antibiotic drugs. |
LAANA Truta Implementation and validation of a GC/MS/MS method to determine antidepressives in total blood (Masters Thesis) Supervision: AL Castro, S Tarelho, P Costa, MGF Sales, HM Teixeira. Instituto Superior de Engenharia do Porto, 2012. @mastersthesis{Truta2012, title = {Implementation and validation of a GC/MS/MS method to determine antidepressives in total blood}, author = {LAANA Truta }, url = {http://hdl.handle.net/10400.22/2556}, year = {2012}, date = {2012-01-10}, school = {Supervision: AL Castro, S Tarelho, P Costa, MGF Sales, HM Teixeira. Instituto Superior de Engenharia do Porto}, abstract = {Depression is one of the most prevalent psychiatric disorders in our society. Solid epidemiological evidence suggests a substantial incidence of the disease in recent years. This is supported by a significant increase in the consumption of antidepressant drugs, creating the need of suitable methods for their accurate analysis in blood samples, carried out in a routine fashion. Focusing the needs of the Serviço de Toxicologia Forense do Instituto Nacional de Medicina Legal, Delegação do Norte, it is important to develop an analytical methodology for the simultaneous determination of 15 antidepressant drugs in whole blood and to validate it with regard to several analytical parameters. The selected antidepressants are Amitriptyline, Citalopram, Clomipramine, N-Desmethylclomipramine, Doxepine, Fluoxetine, Imipramine, Maprotiline, Mianserine, Mirtazapine, Nortriptyline, Paroxetine, Sertraline, Trimipramine e Venlafaxine. GC/MS/MS was selected for this purpose, after carrying out suitable pre-treating solid-phase extraction procedures. This selection was grounded on the fact that the identification of every compound is ensured and the resulting method offers high sensitivity with low limits of detection. The analytical parameters required for validation included selectivity/specificity and identification capability; limits of detection and quantification; linearity and working concentration range; extraction efficiency; carryover; accuracy (precision, trueness and uncertainty); and robustness. Excluding accuracy that still needs additional testing, all parameters were validated according to the requisites of the Serviço de Toxicologia Forense do Instituto Nacional de Medicina Legal, Delegação do Norte. In general, the obtained results offered good selectivity and analytical responses for the typical concentration ranges of therapeutic and lethal levels. The extraction procedures were effective and no carryover was observed for the highest concentrations. The overall method was found robust.}, keywords = {}, pubstate = {published}, tppubtype = {mastersthesis} } Depression is one of the most prevalent psychiatric disorders in our society. Solid epidemiological evidence suggests a substantial incidence of the disease in recent years. This is supported by a significant increase in the consumption of antidepressant drugs, creating the need of suitable methods for their accurate analysis in blood samples, carried out in a routine fashion. Focusing the needs of the Serviço de Toxicologia Forense do Instituto Nacional de Medicina Legal, Delegação do Norte, it is important to develop an analytical methodology for the simultaneous determination of 15 antidepressant drugs in whole blood and to validate it with regard to several analytical parameters. The selected antidepressants are Amitriptyline, Citalopram, Clomipramine, N-Desmethylclomipramine, Doxepine, Fluoxetine, Imipramine, Maprotiline, Mianserine, Mirtazapine, Nortriptyline, Paroxetine, Sertraline, Trimipramine e Venlafaxine. GC/MS/MS was selected for this purpose, after carrying out suitable pre-treating solid-phase extraction procedures. This selection was grounded on the fact that the identification of every compound is ensured and the resulting method offers high sensitivity with low limits of detection. The analytical parameters required for validation included selectivity/specificity and identification capability; limits of detection and quantification; linearity and working concentration range; extraction efficiency; carryover; accuracy (precision, trueness and uncertainty); and robustness. Excluding accuracy that still needs additional testing, all parameters were validated according to the requisites of the Serviço de Toxicologia Forense do Instituto Nacional de Medicina Legal, Delegação do Norte. In general, the obtained results offered good selectivity and analytical responses for the typical concentration ranges of therapeutic and lethal levels. The extraction procedures were effective and no carryover was observed for the highest concentrations. The overall method was found robust. |