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Ultrasound-assisted protein-enhanced graphene synthesis for rapid electrochemical antibody sensing
Publication . Cardoso, Ana R.; Suleimenova, A.; Alves, João Frederico; Frasco, Manuela F.; Barquinha, Pedro; Sales, M. Goreti F.; CENIMAT-i3N - Centro de Investigação de Materiais (Lab. Associado I3N); DCM - Departamento de Ciência dos Materiais; UNINOVA-Instituto de Desenvolvimento de Novas Tecnologias; Elsevier
This study presents a novel method for the fabrication of graphene as a functional interface for electrochemical sensors. Graphene was synthesized by probe-assisted ultrasonic exfoliation of graphite stabilized by the SARS-CoV-2 spike (S) protein. In this dual-function approach, the S protein is used for both graphene stabilization and antibody recognition, simplifying the production of biosensors. The biosensor was fabricated by modifying a carbon working electrode with the stabilized graphene-S-protein complex. Electrochemical impedance spectroscopy revealed a linear detection range from 1.0 pg/mL to 10.0 ng/mL in diluted human serum, with a detection limit of 0.17 pg/mL. The high selectivity for the S protein was confirmed against the SARS-CoV-2 nucleocapsid protein. The device successfully analysed serum samples, demonstrating its practical application. These results emphasize a simple, innovative platform that integrates graphene synthesis and biosensor functionality. This approach not only ensures a sensitive and stable substrate for monitoring antibodies against SARS-CoV-2, but also offers an approach that can be extended to detect different antibodies, by selecting the stabilizing protein that binds to the intended antibody.
Enzyme-Free Monitoring of Glucose Using Molecularly Imprinted Polymers and Gold Nanoparticles
Publication . Cardoso, Ana Rita Aires; Barquinha, Pedro Miguel Cândido; Sales, Maria Goreti Ferreira; CENIMAT-i3N - Centro de Investigação de Materiais (Lab. Associado I3N); UNINOVA-Instituto de Desenvolvimento de Novas Tecnologias; DCM - Departamento de Ciência dos Materiais; MDPI - Multidisciplinary Digital Publishing Institute
This work describes a non-enzymatic electrochemical glucose biosensor combining for the first time molecularly imprinted polymers (MIPs) for glucose concentration and gold nanoparticles (AuNPs) on screen-printed carbon electrodes (SPEs), where both MIPs and AuNPs were assembled in situ. Electrochemical impedance spectroscopy (EIS) was used to evaluate the analytical performance of the sensor, which has a linear range between 1.0 µM and 1.0 mM when standard solutions are prepared in buffer. Direct measurement of glucose was performed by chronoamperometry, measuring the oxidation current generated during direct glucose oxidation. The selectivity was tested against ascorbic acid and the results confirmed a selective discrimination of the electrode for glucose. Overall, the work presented here represents a promising tool for tracking glucose levels in serum. The use of glucose MIP on the electrode surface allows the concentration of glucose, resulting in lower detection limits, and the use of AuNPs reduces the potential required for the oxidation of glucose, which increases selectivity. In addition, this possible combination of two analytical measurements following different theoretical concepts can contribute to the accuracy of the analytical measurements. This combination can also be extended to other biomolecules that can be electrochemically oxidised at lower potentials.
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SFRH/BD/130107/2017