Effect of Multi-Walled Carbon Nanotubes on Glucose Oxidation by Glucose Oxidase or a Flavin-Dependent Glucose Dehydrogenase in Redox-Polymer-Mediated Enzymatic Fuel Cell Anodes

The addition of multi-walled carbon nanotubes (MWCNTs) to enzymatic electrodes based on either glucose oxidase (GOx), or an oxygen-insensitive flavin adenine dinucleotide-dependent glucose dehydrogenase (FADGDH), increases the amount of {Os(4,4-dimethyl-2,2-bipyridine)(2)[poly(vinylimidazole)](10)Cl}Cl redox polymer at the electrode surface, indicating that MWCNTs provide a surface for the immobilisation of film components. Glucose oxidation is highest for films with 68% (w/w) MWCNTs, and a decrease is observed with larger amounts; this decrease is related to a decrease in retained enzyme activity. Enzymatic electrodes provide 4.2mAcm(-2) current density at 0.12V versus Ag/AgCl, for GOx-based electrodes, compared to 2.7mAcm(-2) for FADGDH-based electrodes in 50mM phosphate-buffered saline containing 150mM NaCl at 37 degrees C. Current densities of 0.52 and 1.1mAcm(-2) are obtained for FADGDH and GOx-based electrodes, respectively, operating at physiologically relevant 5mM glucose concentrations. These enzymatic electrodes, thus, show promise for application as anodes in enzymatic fuel cells for invivo or exvivo power generation.