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Type: Artigo de periódico
Title: Electrochemical Investigations Of The Reaction Mechanism And Kinetics Between Nadh And Redox-active (nc)2c6h3-nhoh/(nc)2c6h3-no From 4-nitrophthalonitrile-(nc)2c6h3-no2-modified Electrode.
Author: Lima, Phabyanno Rodrigues
Santos, Wilney de Jesus Rodrigues
de Oliveira, Adriano Bof
Goulart, Marília Oliveira Fonseca
Kubota, Lauro Tatsuo
Abstract: A simple and sensitive method for the electrocatalytic detection of NADH on a carbon paste electrode modified with a redox-active (NC)(2)C(6)H(3)-NO/(NC)(2)C(6)H(3)-NHOH (NOPH/NHOHPH) electrogenerated in situ from 4-nitrophthalonitrile (4-NPHN) is presented. The electrode modified with 4-NPHN showed an efficient electrocatalytic activity towards the oxidation of NADH with activation overpotential of 0.12V vs. Ag/AgCl. The formation of an intermediate charge transfer complex is proposed for the charge transfer reaction between NADH and the 4-NPHN-resulting system. The second-order rate constant for electrocatalytic oxidation of NADH, kappa(obs), and the apparent Michaelis-Menten constant K(M), at pH 7.0 were evaluated with rotating disk electrode (RDE) experiments, giving 1.0 x 10(4)mol(-1)Ls(-1) and 2.7 x 10(-5)mol L(-1), respectively. Employing the Koutecky-Levich approach indicated that the NADH oxidation reaction involves two electrons. The sensor provided a linear response range for NADH from 0.8 up to 8.5 micromol L(-1) with sensitivity, detection, quantification limits and time response of 0.50 microA L micromol(-1), 0.25micromol L(-1), 0.82 micromol L(-1) and 0.1s, respectively. The repeatability of the measurements with the same sensor and different sensors, evaluated in terms of relative standard deviation, were 4.1 and 5.0%, respectively, for n=10.
Subject: Biosensing Techniques
Rights: fechado
Identifier DOI: 10.1016/j.bios.2008.04.023
Date Issue: 2008
Appears in Collections:Unicamp - Artigos e Outros Documentos

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