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1.
Biosens Bioelectron ; 86: 308-314, 2016 Dec 15.
Artículo en Inglés | MEDLINE | ID: mdl-27387261

RESUMEN

We report for the first time the use of single-walled carbon nanotubes (SWCNT) covalently functionalized with polytyrosine (Polytyr) (SWCNT-Polytyr) as a new electrode material for the development of nicotinamide adenine dinucleotide (NADH)-based biosensors. The oxidation of glassy carbon electrodes (GCE) modified with SWCNT-Polytyr at potentials high enough to oxidize the tyrosine residues have allowed the electrooxidation of NADH at low potentials due to the catalytic activity of the quinones generated from the primary oxidation of tyrosine without any additional redox mediator. The amperometric detection of NADH at 0.200V showed a sensitivity of (217±3)µAmM(-1)cm(-2) and a detection limit of 7.9nM. The excellent electrocatalytic activity of SWCNT-Polytyr towards NADH oxidation has also made possible the development of a sensitive ethanol biosensor through the immobilization of alcohol dehydrogenase (ADH) via Nafion entrapment, with excellent analytical characteristics (sensitivity of (5.8±0.1)µAmM(-1)cm(-2), detection limit of 0.67µM) and very successful application for the quantification of ethanol in different commercial beverages.


Asunto(s)
Alcohol Deshidrogenasa/química , Conductometría/instrumentación , Etanol/análisis , NAD/análisis , Nanotubos de Carbono/química , Péptidos/química , Enzimas Inmovilizadas/química , Diseño de Equipo , Análisis de Falla de Equipo , NAD/química , Nanoconjugados/química , Nanoconjugados/ultraestructura , Nanotubos de Carbono/ultraestructura , Oxidación-Reducción , Reproducibilidad de los Resultados , Sensibilidad y Especificidad
2.
Anal Chim Acta ; 909: 51-9, 2016 Feb 25.
Artículo en Inglés | MEDLINE | ID: mdl-26851084

RESUMEN

This work reports the synthesis and characterization of single-walled carbon nanotubes (SWCNT) covalently functionalized with polytyrosine (Polytyr); the critical analysis of the experimental conditions to obtain the efficient dispersion of the modified carbon nanotubes; and the analytical performance of glassy carbon electrodes (GCE) modified with the dispersion (GCE/SWCNT-Polytyr) for the highly sensitive quantification of polyphenols. Under the optimal conditions, the calibration plot for the amperometric response of gallic acid (GA) shows a linear range between 5.0 × 10(-7) and 1.7 × 10(-4) M, with a sensitivity of (518 ± 5) m AM(-1) cm(-2), and a detection limit of 8.8 nM. The proposed sensor was successfully used for the determination of total polyphenolic content in tea extracts.


Asunto(s)
Nanotubos de Carbono/química , Péptidos/química , Polifenoles/análisis , Electrodos , Ácido Gálico/química , Estructura Molecular
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