Stability improvement by crosslinking of previously immobilized glucose oxidase on carbon nanotube-based bioanode

Bioanode stability with glucose oxidase was enhanced significantly by covalent crosslinking without substantial enzymatic activity and affinity loss. Initially, glucose oxidase was immobilized by aldehyde groups on the electrode that was developed using ferrocenecarboxaldehyde, polyethyleneimine, multiwall carbon nanotubes, and carbon cloth for biofuel cell applications. The glucose oxidase half-life was extended by more than 4 times, from 27.2 to 124.7 h, after the electrode was crosslinked. Enzymatic kinetic parameters were determined for the crosslinked enzyme and they were compared to the noncrosslinked immobilized enzyme parameters on the electrode. The apparent substrate affinity of the crosslinked enzyme electrode was decreased (i.e. k(M) was increased) by 16%, while the maximum reaction rate was decreased by only 3%, by the crosslinking process. Moreover, effects of the electrolyte type (i.e. buffer type) and concentration on the performance of the crosslinked enzyme electrode were evaluated and appropriate conditions were determined.