Graphene/polyaniline/gold nanoparticles nanocomposite for the direct electron transfer of glucose oxidase and glucose biosensing

A novel glucose biosensor was developed based on the direct electrochemistry of glucose oxidase (GOD) adsorbed in graphene/polyaniline/gold nanoparticles (AuNPs) nanocomposite modified glassy carbon electrode (GCE). Compared with graphene, polyanilline (PANI) or graphene/PANI, the graphene/PANI/AuNPs nanocomposite was more biocompatible and it offered a favorable microenvironment for facilitating the direct electron transfer between GOD and electrode. The adsorbed GOD displayed a pair of well-defined quasi-reversible redox peaks with a formal potential of −0.477 V (vs. SCE) and an apparent electron transfer rate constant (ks) of 4.8 s−1 in 0.1 M pH 7.0 PBS solution. The apparent Michaelis–Menten constant of the adsorbed GOD was 0.60 mM, implying a fabulous catalytic activity and a remarkable affinity of the adsorbed GOD for glucose. The amperometric response of GOD-graphene/PANI/AuNPs modified electrode was linearly proportional to the concentration of glucose in the range of 4.0 μM to 1.12 mM with a low detection limit of 0.6 μM at signal-to-noise of 3. The combination of the direct electron transfer character of GOD and the promising feature of graphene/PANI/AuNPs nanocomposite favors the selective and sensitive determination of glucose with improved analytical capabilities.