Enzyme Functionalized Metal Nanostructures for Enhanced Electrochemical Detection of Lactate

Lactate is a key molecule in the anaerobic carbohydrate metabolism ­of glucose in muscles. It is primarily considered as the biomarker for tissue oxidative stress. Heavy workout, heart failure, liver disease, drug toxicity and different cancer types causes excess production of lactate in sweat and blood. Therefore the measurement of lactate is important for clinical emergencies, sports and in general medicine. Even though there are reports in literature about lactate sensing, gold nanoparticles functionalized with the enzyme lactate oxidase using disulphide crosslinkers shows promising catalytic activity. In this work, a ultrasensitive biosensor was fabricated by covalently immobilizing lactate oxidase on self-assembled monolayer (SAM) on the gold nanoparticles modified screen printed electrodes (SPE). The sensing mechanism involves the detection of hydrogen peroxide produced during the enzymatic oxidation of lactate. Scanning electron microcopy and cyclic voltammetry were used to characterize the fabricated biosensor. The results show that SAM on uniformly deposited gold nanoparticles provides a favorable microenvironment to retain the bioactivity of enzyme towards lactate detection. The proposed lactate biosensor exhibited good analytical performances including high sensitivity and selectivity with satisfactory stability to electrochemical determination of lactate.