Role of Conductive Nanoparticles in the Direct Unmediated Bioelectrocatalysis of Immobilized Sulfite Oxidase

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• 作者：Ting Zeng ; Stefano Frasca ; Jens Rumschö ; ttel ; Joachim Koetz ; Silke Leimkü ; hler and Ulla Wollenberger
• 刊名：Electroanalysis
• 出版年：2016
• 出版时间：October 2016
• 年：2016
• 卷：28
• 期：10
• 页码：2303-2310
• 全文大小：1167K
• ISSN：1521-4109

文摘

We report efficient bioelectrocatalytic sulfite oxidation by human sulfite oxidase (hSO) immobilized on a gold nanoparticle (AuNP) modified gold electrode. The AuNP were synthesized in aqueous phase by using branched polyethyleneimine (PEI) as reducing as well as stabilizing agent. Gold electrodes were modified by a self assembled monolayer of dithio-bis(N-hydroxysuccinimidyl propionate) (DTSP) onto which the NP and hSO were immobilized. Cyclic voltammetry of the hSO modified electrode in the absence of substrate revealed a quasi-reversible direct electrochemical reaction of the heme domain of hSO with fast electron transfer rate. The electron transfer rate constant of k_s=32 s⁻¹ and the formal potential E⁰′=−0.155 V vs. Ag/AgCl/1 M KCl were estimated. Comparative studies with nanoparticles of BaSO₄ indicate the importance of the NP conductivity for charge transfer and enhancement of direct electron transfer communication. Sulfite addition resulted in a largely enhanced oxidation current at low overpotential. Use of longer thiols for assembly of the AuNP resulted in a decrease of electron transfer rate and increase of overpotential for sulfite bioelectrocatalysis. The electrode modified with DTSP and AuNP exhibited a very high steady state catalytic current density of 1 µA/cm². The assembly can be applied for the amperometric biosensing of sulfite at a potential of 0 mV vs. Ag/AgCl/1 M KCl.