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

► GCE was modified with Au nanoparticles decorated overoxidized polypyrrole film. ► DET reaction was observed for glucose oxidase immobilized on modified electrode. ► The formal potential of the observed well-defined redox peaks was about −0.449 V. ► The peak to peak separation value for the observed redox peaks was about 28 mV. ► The apparent electron transfer rate constant was measured to be 10.3 s−1.