Abstract
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 25μM. The bioelectrode sensitivity, calculated against the superficial surface area of the bioelectrode, was of 22.7±0.1μAmM−1cm−2.This glucose oxidase electrode was also tested as an anode in a glucose/O2 enzymatic biofuel cell, leading to a peak power density of 6μWcm−2 at a potential of 0.2V.
Highlights
The functional immobilisation of redox enzymes, such as laccase and glucose oxidase, onto electrode material surfaces is of keen interest for sensors and biofuel cells development.Enzymes are the most common bioreceptor molecules used in biosensors due to their extremely high specificity that leads to minimal risk of false positive responses
This study reports for the first time, an efficient, simple, costeffective, and rapid method for the functional immobilisation of Glucose Oxidase (GOx) onto highly porous gold (hPG) surfaces
The purpose of this study was to investigate the possibility to develop a more rapid and reproducible immobilization protocol of GOx onto hPG electrodes with respect to those so far reported that involve the use of thiol groups or conductive polymers [24,28]. This was achieved by running a series of Cyclic voltammetry (CV) scans of a hPG electrode in a GOx buffer solution, with the aim of increasing enzyme loading and affinity through the use of electrostatic forces
Summary
The functional immobilisation of redox enzymes, such as laccase and glucose oxidase, onto electrode material surfaces is of keen interest for sensors and biofuel cells development.Enzymes are the most common bioreceptor molecules used in biosensors due to their extremely high specificity that leads to minimal risk of false positive responses. The functional immobilisation of redox enzymes, such as laccase and glucose oxidase, onto electrode material surfaces is of keen interest for sensors and biofuel cells development. The implementation of enzymes in biofuel cells allows for the development of membraneless and compartment-less devices, which can be miniaturised, but can be used in situations where it is not feasible to separate the fuel and oxidant [1]. For these applications, the achievement of efficient electron transfer between the enzyme active centre and the electrode is critical. The mediators can be polymerised directly onto the electrode surface or co-immobilised with the reacting enzymes to further enhance the rate of electron transfer [4,5]
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