Direct Electrochemistry of Glucose Oxidase on a GrapheneGraphene Oxide Nanocomposite-Modified Electrode for a Glucose Biosensor

Abstract

Direct electrochemistry of glucose oxidase (GOD) was conducted on the surface of a novel graphenegraphene oxide (GR-GO) nanocomposite. GR-GO possesses the virtues of excellent biocompatibility and conductivity, and high sensitivity to local perturbations, and can provide a biocompatible microenvironment for protein immobilization and a suitable electron transfer distance between the electroactive centers of GOD and the electrode surface. The voltammetric results indicated that GOD assembled on GR-GO retained its native structure and bioactivity, exhibited a surface-confined process, and underwent an effective direct electron transfer (DET) reaction with an apparent rate constant (ks) of 3.5 s-1. Furthermore, the proposed biosensor exhibited a wider linear response to glucose concentrations between 0.1 mM and 11 mM, with a detection limit of 20 μM and a much higher sensitivity (15.85 pA mM-1 cm-2).