Crosslinked redox polymer enzyme electrodes containing carbon nanotubes for high and stable glucoseoxidation current

Abstract

Co-immobilisation approaches for preparation of glucose-oxidising films of [Os(2,2′-bipyridine)₂(poly-vinylimidazole)₁₀Cl] and glucose oxidase on glassy carbon electrodes are compared. Electrodes prepared by crosslinking using glutaraldehyde vapour, without and with a NaBH₄ reduction, provide higher glucose oxidation current than those prepared using a well-established diepoxide method. Addition of multi walled carbon nanotubes to the film deposition solutions produces an enhanced glucose oxidation current density of 5 mA cm⁻² at 0.35 V vs. Ag/AgCl, whilst improving the operational stability of the current signal. Carbon nanotube, glutaraldehyde vapour crosslinked, films on electrodes, reduced by NaBH₄, retain 77% of initial catalytic current over 24 hours of continuous amperometric testing in a 37 °C, 50 mM phosphate buffer solution containing 150 mM NaCl and 100 mM glucose. Potential application of this approach to implantable enzymatic biofuel cells is demonstrated by production of glucose oxidation currents, under pseudo-physiological conditions, using mediating films with lower redox potentials.