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Type: Artigo de periódico
Title: Electrochemical investigations of the reaction mechanism and kinetics between NADH and redox-active (NC)(2)C6H3-NHOH/(NC)(2)C6H3-NO from 4-nitrophthalonitrile-(NC)(2)C6H3-NO2-modified electrode
Author: Lima, PR
Santos, WDR
de Oliveira, AB
Goulart, MOF
Kubota, LT
Abstract: A simple and sensitive method for the electrocatalytic detection of NADH on a carbon paste electrode modified with a redox-active (NC)(2)C6H3-NO/(NC)(2)C6H3-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 0.12 V vs. Ag/AgCl. The formation of all 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 mu mol L-1 with sensitivity, detection, quantification limits and time response of 0.50 mu A L mu mol(-1), 0.25 mu mol L-1, 0.82 mu mol L-1 and 0.1 s. 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. (C) 2008 Elsevier B.V. All rights reserved.
Subject: 4-nitrophthalonitrile
mechanism and kinetics
Country: Inglaterra
Editor: Elsevier Advanced Technology
Citation: Biosensors & Bioelectronics. Elsevier Advanced Technology, v. 24, n. 3, n. 448, n. 454, 2008.
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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