The synergetIc effect of redox mediators and peroxidase in a bienzymatic biosensor for glucose assays in FIA

A bienzymatic biosensor incorporating a mediator has been developed in order to achieve a fast and selective detection of glucose in a flow injection system. The working electrode is based on a carbon paste matrix bulk modified with glucose oxidase (GOD) and horseradish peroxidase (HRP) as well as with ferrocene acting as an electron transfer mediator between the electrode and HRP. The proximity of these three components enhances the electron transfer within the electrode. Simple polishing on a paper sheet easily renews the electrode surface. Moreover, the applied working potential (-0.050 V vs. Ag/AgCl) is low, hereby decreasing the interference from electroactive compounds and thus increasing the selectivity of the biosensor. The characteristics of the developed bienzymatic electrode are presented in terms of sensitivity, linear detection range, accuracy and operational stability.