Membraneless glucose/oxygen enzymatic fuel cells using redox hydrogel films containing carbon nanotubes.

Co-immobilisation of three separate multiple blue copper oxygenases, a Myceliophthora thermophila laccase, a Streptomyces coelicolor laccase and a Myrothecium verrucaria bilirubin oxidase, with an [Os(2,2-bipyridine)(2)(polyvinylimidazole)(10)Cl](+/2+) redox polymer in the presence of multi-walled carbon nanotubes (MWCN (-2) for oxygen reduction at an applied potential of 0 V versus Ag/AgCl. Fully enzymatic membraneless fuel cells are assembled with the oxygen-reducing enzyme electrodes connected to glucose-oxidising anodes based on co-immobilisation of glucose oxidase or a flavin adenine dinucleotide-dependent glucose dehydrogenase with an [Os(4,4-dimethyl-2,2-bipyridine)(2)(polyvinylimidazole)(10)Cl](+/2+) redox polymer in the presence of MWCN (-2) on operation in pH 7.4 phosphate buffer solution at 37 degrees C containing 150 mM NaCl, 5 mM glucose and 0.12 mM O-2. Myceliophthora thermophila laccase enzyme electrodes produce the highest power density if combined with glucose oxidase-based anodes. Although the maximum power density of a fuel cell of glucose dehydrogenase and Myceliophthora thermophila laccase enzyme electrodes decreases from 110 Wcm(-2) in buffer to 60 Wcm(-2) on testing in artificial plasma, it provides the highest power output reported to date for a fully enzymatic glucose-oxidising, oxygen-reducing fuel cell in artificial plasma.