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 O 2 reduction and performing direct electron transfer (DET) between native GOx, GC, and O 2 . DET, however, was not detected between native GOx and glucose or H 2 O 2 . EIS results allowed resistance to electron hopping ( R eh ) to be estimated between redox centers in native GOx and between these centers and O 2 molecules (around 300 Ω). This resistance exhibited very high values for glucose (45.5 kΩ) and H 2 O 2 (14.6 kΩ in 50 mM H 2 O 2 ) molecules, thereby preventing DET between redox centers in native GOx and between these centers and glucose or H 2 O 2 molecules.