Reactivity of a glucose oxidase electrode in a polar organic solvent

Abstract

The performance of an amperometric glucose sensor in the polar organic solvent butan-2-ol has been evaluated by using ferrocene monocarboxylic acid (FMCA) as a soluble mediator. I_max and K′_MG(apparent Michaelis–Menten constant for glucose) were found to be 14.5 µA cm^–2 and 21.7 mmol l^–1, respectively, in butan-2-ol. The corresponding values in aqueous medium are 15.4 µA cm^–2 and 16.7 mmol l^–1. The higher K′_MG value in butan-2-ol resulted in a decrease in the apparent catalytic efficiency (k_cat[E]l/K′_MG) of the biosensor in this solvent compared with the aqueous phase. This suggests the stripping of water from the enzyme active site by the polar butan-2-ol. The Hill coefficient values (x= 0.86 in butan-2-ol and 0.80 in aqueous medium) indicate that the polar organic solvent does not alter the reactivity of the sensor, but may even correct the deviation from Michaelis–Menten kinetics brought about by enzyme immobilization.