Persistent Direct Electron Transfer between O2 and Glucose Oxidase Embedded in Polymyxin Supported on a Glassy Carbon Electrode

Abstract

In this study, glucose oxidase (GOx) embedded in polymyxin (PM) adsorbed on glassy carbon (GC) and covered with Nafion was investigated by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and hydrodynamic voltammetry (HV). The hybrid GC/PM-GOx/Nafion electrode thus formed was capable of persistently bioelectrocatalyzing O2 reduction and performing direct electron transfer (DET) between native GOx, GC, and O2. DET, however, was not detected between native GOx and glucose or H2O2. EIS results allowed resistance to electron hopping (Reh) to be estimated between redox centers in native GOx and between these centers and O2 molecules (around 300 Ω). This resistance exhibited very high values for glucose (45.5 kΩ) and H2O2 (14.6 kΩ in 50 mM H2O2) molecules, thereby preventing DET between redox centers in native GOx and between these centers and glucose or H2O2 molecules.