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 hors eradish peroxidase together with electrochemical mediator was incorpor ated within the graphite paste electrode. The amperometric response is based on the mediated electrochemical regeneration of peroxidase with in the paste. The mediated electrochemical regeneration of peroxidase and glucose oxidase was studied and compared using three different ele ctron transfer mediators - tetracyanoquinodimethane (TCNQ), tetrathiaf ulvalene (TTF), and dimethyl ferrocene (dmFc). The mediated electroche mistry 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 a nd dmFc. On the other hand, TCNQ is better mediator for the developmen t of glucose sensor. The response curves for peroxide have been report ed using these three mediators. A comparative study on the amperometri c response based on the mediated electrochemical oxidation of peroxida se and glucose oxidase has also been made using these three mediators. The various parameters, i.e., background current, stability of the me diator within the graphite paste during the electrochemical measuremen ts, and reproducibility of the amperometric response, are discussed. ( C) 1997 Academic Press.