Self-assembled glucose oxidase/graphene/gold ternary nanocomposites for direct electrochemistry and electrocatalysis

Graphene-gold nanoparticle nanocomposites (GR-AuNPs) were synthesized and used as a matrix for glucose oxidase (GOD) immobilization in glucose sensing. Using layer-by-layer (LBL) method, a multilayered GOD sensor was constructed by alternatively immobilizing GR-AuNPs and GOD on electrodes. The immobilized GOD displayed a couple of stable and well-defined redox peaks with an electron transfer rate constant of 3.25 s(-1) and a formal potential of -0.452 V in 0.1 mol L-1 pH 7.0 phosphate buffer solution (PBS). The apparent Michaelis-Menten constant for glucose was 0.038 mmol L-1. This method allowed to detect glucose with a sensitivity of 3.844 mu A mmol L-1 cm(-2), a linear range from 0.02 to 2.26 mmol L-1, and a detection limit of 4.10 mu mol L-1 (S/N = 3). The results indicated that the proposed graphene-gold nanoparticle nanocomposites were good platforms for enzyme immobilization, thus facilitating the direct electron transfer and biosensing application. (C) 2013 Elsevier B.V. All rights reserved.