Peroxide biosensors and mediated electrochemical regeneration of redox enzymes.

This article describes the research investigations on the development of the amperometric biosensors based on mediated bioelectrochemistry. The mediated bioelectrochemistry involving horseradish peroxidase and glucose oxidase within the graphite paste is reported. The enzyme horseradish peroxidase together with electrochemical mediator was incorporated within the graphite paste electrode. The amperometric response is based on the mediated electrochemical regeneration of peroxidase within the paste. The mediated electrochemical regeneration of peroxidase and glucose oxidase was studied and compared using three different electron transfer mediators-tetracyanoquinodimethane (TCNQ), tetrathiafulvalene (TTF), and dimethyl ferrocene (dmFc). The mediated electrochemistry involving these three mediators was studied based on the cyclic voltammetry. The electrochemical measurements show that TTF is better mediator for the development of peroxide biosensor compared to TCNQ and dmFc. On the other hand, TCNQ is better mediator for the development of glucose sensor. The response curves for peroxide have been reported using these three mediators. A comparative study on the amperometric response based on the mediated electrochemical oxidation of peroxidase and glucose oxidase has also been made using these three mediators. The various parameters, i.e., background current, stability of the mediator within the graphite paste during the electrochemical measurements, and reproducibility of the amperometric response, are discussed.