Amperometric L‐Lactate biosensor based on gold nanoparticles

Abstract

A novel amperometric biosensor for the sensing of L-lactate is developed using L-lactate dehydrogenase (LDH) and hydroxylamine enlarged gold nanoparticles (GNPs). LDH and GNPs have been integrated with the sol–gel 3-D silicate network derived from 3-(mercaptopropyl)trimethoxysilane (MPTS). The biosensing of L-lactate is based on the electrocatalytic determination of enzymatically generated NADH by GNPs of the integrated assembly. The GNPs on the network efficiently catalyze the oxidation of NADH at −0.065 V, which is ca. 915 mV less positive than on the bulk Au electrode. The biosensor was characterized in terms of the effects of enzyme loading, solution pH, and cofactor concentration. The integrated biosensor was successfully utilized for the amperometric sensing of L-lactate and it shows excellent sensitivity with a detection limit of 100 nM. The common interfering electroactive compounds in the biological system do not interfere the amperometric measurement of L-lactate. This biosensor linearly responds to L-lactate in the range of 0–0.8 mM and the sensitivity of the electrode was 0.446 nA/nM. Excellent reproducibility, long time storage and operational stability have been achieved.