Coupling osmium complexes to epoxy-functionalised polymers to provide mediated enzyme electrodes for glucose oxidation

Newly synthesised osmium complex-modified redox polymers were tested for potential application as mediators in glucose oxidising enzyme electrodes for application to biosensors or biofuel cells. Coupling of osmium complexes containing amine functional groups to epoxy-functionalised polymers of variable composition provides a range of redox polymers with variation possible in redox potential and physicochemical properties. Properties of the redox polymers as mediators for glucose oxidation were investigated by co-immobilisation onto graphite with glucose oxidase or FAD-dependent glucose dehydrogenase using a range of crosslinkers and in the presence and absence of multiwalled carbon nanotubes. Electrodes prepared by immobilising [P20-Os(2,2′-bipyridine)2(4-aminomethylpyridine)Cl].PF6, carbon nanotubes and glucose oxidase exhibit glucose oxidation current densities as high as 560 μA cm−2 for PBS containing 100 mM glucose at 0.45 V vs. Ag/AgCl. Films prepared by crosslinking [P20-Os(4,4′-dimethoxy-2,2′-bipyridine)2(4-aminomethylpyridine)Cl].PF6, an FAD-dependent glucose dehydrogenase, and carbon nanotubes achieve current densities of 215 μA cm−2 in 5 mM glucose at 0.2 V vs. Ag/AgCl, showing some promise for application to glucose oxidising biosensors or biofuel cells.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Novel osmium redox polymers prepared using covalent binding approach. ► Enzyme electrodes using redox polymers, enzymes and multiwalled carbon nanotubes provide high current density for glucose oxidation. ► J of 215 μA cm−2 for 5 mM glucose PBS solutions at 0.2 V vs. Ag/AgCl.