Electrochemical characteristics of a carbon-based thick-film l-lactate biosensor using l-lactate dehydrogenase

Carbon-based thick-film electrodes employing nicotinamide adenine dinucleotide (NAD+)-dependent dehydrogenases were constructed by screen printing. Cyclic voltammetric and amperometric investigations of the thick-film electrode showed significantly different electrocatalytic properties toward NADH compared to conventional polished electrodes. Electrochemical oxidation of NADH was attained at the low potential of +350 mV vs. AgAgCl at the thick-film carbon electrode, and this can be attributed to increased electrocatalytic sites due to the rough and jagged electrode surface and the formation of a microelectrode array-like structure at the electrode surface. Based on these observations, a thick-film lactate biosensor using lactate dehydrogenase was developed. Analytical performance of the resulting lactate biosensor was evaluated in terms of sensitivity and stability.