High current, low redox potential mediatorless bioanode based on gold nanoparticles and glucose dehydrogenase from Ewingella americana

The action of bacterial glucose dehydrogenase (GDH) from Ewingella americana on the gold nanoparticles (AuNPs) modified with 4-aminothiophenol (4-ATP) and 4-mercaptobenzoic acid (4-MBA) was studied. GDH adsorbed on these nanostructured electrodes catalysed glucose oxidation in a mediator-free manner. The voltammetric investigations suggested the direct electron transfer between the enzyme active centre and the electrode. The maximum biocatalytic current of 10 mA cm(-2) and low onset potential (-0.22 V vs. SCE) was observed in assays containing AuNPs modified with 4-ATP. The turnover number of the adsorbed enzyme was determined as 28 +/- 5 s(-1) and is comparable to catalytic constant (36 +/- 5 s(-1)) of the native enzyme in the solution. The kinetic model of the action of AuNPs-GDH system comprising Michaelis-Menten and Butler-Volmer equations was analysed and the analytical solution of the dependence of the biocatalytic current on kinetic parameters of the enzyme was derived. (C) 2016 Elsevier Ltd. All rights reserved.