DEVELOPMENT OF MEDIATED AMPEROMETRIC BIOSENSORS FOR HYPOXANTHINE, GLUCOSE AND LACTATE - A NEW FORMAT

Electrochemical growth was used to form the organic conducting salt of tetrathiafulvalene (TTF) and tetracyanoquinodimethane (TCNQ) on plati num wires inserted in a glass capillary. Glucose oxidase, lactate oxid ase and xanthine oxidase were deposited and crosslinked on the salt st ructure to produce mediated biosensors responsive to the corresponding analytes. Reliability, stability, interference, and the effect of oxy gen on the electrode's response were studied. Among three common elect roactive interfering substances tested, ascorbic acid was very active at the TTF-TCNQ structure and the highest response was exhibited by th e enzyme-free electrode. Acetaminophen and uric acid displayed similar behaviour at a lower magnitude. The presence of oxygen significantly decreased the current responses of all electrodes. The xanthine oxidas e-bearing mediated electrodes were able to assay the hypoxanthine cont ent of either the fish extract, fish homogenate or slurry of manually ground tissue, yielding results in good agreement with conventional en zymatic assays. The electrodes were stable more than 120 days and coul d be reused more than 30 times without losing their original activitie s.