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

Abstract

AbstractThe 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)]10Cl}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 4.2 mA cm−2 current density at 0.12 V versus Ag/AgCl, for GOx‐based electrodes, compared to 2.7 mA cm−2 for FADGDH‐based electrodes in 50 mM phosphate‐buffered saline containing 150 mM NaCl at 37 °C. Current densities of 0.52 and 1.1 mA cm−2 are obtained for FADGDH and GOx‐based electrodes, respectively, operating at physiologically relevant 5 mM glucose concentrations. These enzymatic electrodes, thus, show promise for application as anodes in enzymatic fuel cells for in vivo or ex vivo power generation.