Mediated electron transfer of cellobiose dehydrogenase and glucose oxidase at osmium polymer-modified nanoporous gold electrodes

Nanoporous and planar gold electrodes were utilised as supports for the redox enzymes Aspergillus niger glucose oxidase (GOx) and Corynascus thermophilus cellobiose dehydrogenase (CtCDH). Electrodes modified with hydrogels containing enzyme, Os-redox polymers and the cross-linking agent poly(ethylene glycol) diglycidyl ether were used as biosensors for the determination of glucose and lactose. Limits of detection of 6.0 (+/- 0.4), 16.0 (+/- 0.1) and 2.0 (+/- 0.1) mu M were obtained for CtCDH-modified lactose and glucose biosensors and GOx-modified glucose biosensors, respectively, at nanoporous gold electrodes. Bio-fuel cells composed of GOx- and CtCDH-modified gold electrodes were utilised as anodes, together with Myrothecium verrucaria bilirubin oxidase (MvBOD) or Melanocarpus albomyces laccase as cathodes, in biofuel cells. A maximum power density of 41 mu W/cm(2) was obtained for a CtCDH/MvBOD biofuel cell in 5 mM lactose and O-2-saturated buffer (pH 7.4, 0.1 M phosphate, 150 mM NaCl).