AMPEROMETRIC BIOSENSORS - CHARACTERIZATION OF DISPERSED MEDIATOR SYSTEMS

The quasi-reversible electron transfer of monoalkylated ferrocenes is characterized by cyclic voltammetry and rotating disc measurements. The examined ferrocene derivatives are identified as suitable fast and reversible mediators for a successful application in amperometric glucose biosensors. The reaction between the mono-alkylferrocenes and glucose oxidase is characterized by high reaction rate constants k2 in a reaction kinetics of second order. The size of individual molecules (typically 210-650 pm) in acetonitrite and dispersed mediator aggregates (typically 3500-170 000 pm) in aqueous solutions is estimated from diffusion coefficients. The mediators used in an amperometric biosensor system show fast response upon variations in the glucose concentration. A molecular model is proposed for the reaction mechanism.