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Type: Artigo de periódico
Title: Electrochemical behavior of pyrroloquinoline quinone immobilized on silica gel modified with zirconium oxide
Author: Yamashita, M
Pessoa, CA
Kubota, LT
Abstract: Pyrroloquinoline quinone (PQQ) was immobilized on the silica gel surface modified with zirconium oxide, designated as Si:Zr, by the carboxylic groups of the PQQ molecule and the zirconium oxide on the silica surface. The electrochemistry of PQQ immobilized on the Si:Zr matrix, incorporated in a carbon paste electrode, was evaluated using the cyclic voltammetry technique. The Si:Zr:PQQ-modified electrode showed a redox couple at E-m = (E-pa1 + E-pc)/2 = -0.150 V vs SCE at pH 7, close to that observed in aqueous solution, and another oxidation peak, E-pa2 = -0.100 V vs SCE. Studies in different pH solutions in the range of 3-7 showed that the first oxidation peak, E-pa1, is highly dependent on the solution pH shifting from to -0.175 to 0.100 V vs SCE, while E-pa2 remains practically constant at 0.100 V as the pH decreases from 7 to 3. The immobilized PQQ electrode presented the property to electrocatalyze the NADH at 150 mV vs SCE. The effect of addition of Ca2+ ions on the electrode electroactivity for the NADH oxidation was also verified. Different from that observed for the PQQ immobilized on other electrode materials, the Ca2+ ions did not influence the electrocatalytical response; however, the electrode stability was considerably improved in the presence of Ca2+ ions, indicating that the matrix surface has a great influence on the electrochemical behavior of PQQ. (C) 2003 Elsevier Science (USA). All rights reserved.
Subject: silica gel
zirconium oxide
pyrroloquinoline quinone
carbon paste electrode
NADH oxidation
Country: EUA
Editor: Academic Press Inc Elsevier Science
Citation: Journal Of Colloid And Interface Science. Academic Press Inc Elsevier Science, v. 263, n. 1, n. 99, n. 105, 2003.
Rights: fechado
Identifier DOI: 10.1016/S0021-9797(03)00327-8
Date Issue: 2003
Appears in Collections:Unicamp - Artigos e Outros Documentos

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