Amperometric tetrathiafulvalene-mediated sensor sensitive to reduced nicotinamide adenine dinucleotide based on co-immobilized lactate oxidase and lactate dehydrogenase

An amperometric tetrathiafulvalene (TTF) mediated reduced nicotinamide adenine dinucleotide (NADH) sensor has been fabricated by co-immobilizing lactate oxidase and lactate dehydrogenase on an Eastman-AQ-TTF-modified electrode. The sensor provides low detection limits of 0.01 mmol l(-1) NADH and 1.0 mu mol l(-1) L-lactate and pyruvate by means of amplification of the bioelectrocatalytic oxidation current by the recycling of L-lactate and pyruvate, The response of the sensor to NADH under N-2 saturation reaches a 95% steady-state current within 2 min with a linear response at concentrations of 0.05-2.5 mmol l(-1), The dependence of the apparent Michaelis-Menten constant on applied potential was studied.