COMPARISON OF THE PERFORMANCES OF 2 BI-ENZYMATIC SENSORS FOR THE DETECTION OF D-LACTATE

The performances of two bi-enzymatic amperometric biosensors for the d etection of D-lactate were compared. In both sensors, D-lactate dehydr ogenase was coupled either with diaphorase (which accepts hexacyanofer rate III as an electronic relay) or NADH oxidase (which accepts O-2 as an electronic relay). The enzymes were confined in the reaction chamb er defined by the surface of a flat platinum electrode and a dialysis membrane. The electrochemical detection was based on the oxidation at a platinum electrode of the final enzyme step reaction products (hexac yanoferrate II or hydrogen peroxide). The potential difference applied between two platinum electrodes was respectively 100 mV for hexacyano ferrate II and 550 mV for hydrogen peroxide detection. The performance s of the two biosensors were compared in terms of sensitivity, range o f linearity of the response, storage and operational stability.