CYCLIC VOLTAMMETRY AND CHARGE ACCUMULATION AT CONDUCTING ORGANIC SALTENZYME ELECTRODES

Cyclic voltammetry has been used to study the accumulation of charge a t TTF-TCNQ/glucose oxidase enzyme electrodes. Charge accumulates at en zyme electrodes held at potentials below -50 mV in the presence of enz yme and substrate. The amount of accumulated charge increases as the h olding potential is made more negative, partly because residual oxidat ion is possible at -50 mV and partly because of the corrosion of TTF-T CNQ electrodes which can release species capable of acting as mediator s or enzyme modifiers. Charge accumulation has also been observed at t he normal operating potentials of these enzyme electrodes (50 mV/SCE) when the glucose concentration is greater than 5 mM. At low substrate concentrations when the enzyme electrode current is controlled by memb rane transport no accumulation is observed, but as the substrate conce ntration is increased and electrode kinetics become current controllin g then charge accumulation is observed and is found to increase with i ncreasing glucose concentration.