Glucose Oxidase Directly Immobilized onto Highly Porous Gold Electrodes for Sensing and Fuel Cell applications

The successful implementation of redox-enzyme electrodes in biosensors and enzymatic biofuel cells has been the subject of extensive research. For high sensitivity and high energy-conversion efficiency, the effective electron transfer at the protein-electrode interface has a key role. This is difficult to achieve in the case of glucose oxidase, due to the fact that for this enzyme the redox centre is buried inside the structure, far from any feasible electrode binding sites. This study reports, a simple and rapid methodology for the direct immobilisation of glucose oxidase into highly porous gold electrodes. When the resulting electrode was tested as glucose sensor, a Michaelis-Menten kinetic trend was observed, with a detection limit of 25 mu M. The bioelectrode sensitivity, calculated against the superficial surface area of the bioelectrode, was of 22.7 +/- 0.1 mu A mM(-1) cm(-2). This glucose oxidase electrode was also tested as an anode in a glucose/O-2 enzymatic biofuel cell, leading to a peak power density of 6 mu W cm(-2) at a potential of 0.2V. (C) 2014 The Authors. Published by Elsevier Ltd.