Direct electron transfer from glucose oxidase immobilized on an overoxidized polypyrrole film decorated with Au nanoparticles

An overoxidized polypyrrole (OOPPy) film was electrodeposited on a glassy carbon electrode (GCE) and the modified electrode (GCE/OOPPy) was then decorated with Au nanoparticles (nanoAu). Glucose oxidase was immobilized on the surface of nanoAu decorated OOPPy modified GCE to fabricate a novel glucose biosensor (GCE/OOPPy-nanoAu/GOx). Cyclic voltammetry, electrochemical impedance spectroscopy (EIS) and scanning electron microscopy (SEM) were used to characterize the modified electrodes. A pair of well-defined redox peaks with a formal potential (E°′) of −0.449 V and a peak to peak separation (ΔEp) of 28 mV was observed for the direct electron transfer (DET) of the immobilized GOx. The electron transfer rate constant (ks) was calculated to be 10.3 s−1. The fabricated glucose biosensor was employed for the determination of glucose in the concentration range between 1 and 8 mM using cyclic voltammetry and amperometry. The results clearly demonstrate that nanoAu decorated OOPPy film is an excellent biocompatible scaffold for the immobilization of GOx and fabrication of a glucose biosensor.