Use of L-Lactate Dehydrogenase Immobilized on Carboxylated Multiwalled Carbon Nanotubes/Polyaniline/Pencil Graphite Electrode as a Lactate Biosensor

In this study, L-Lactate dehydrogenase (L-LDH) was covalently immobilized on carboxylated multiwalled carbon nanotubes (cMWCNT)/polyaniline (PANI)/pencil graphite electrode (PGE) and used as a lactate biosensor. Electrochemical polymerization of PANI was carried out using a three-electrode cell technique via cyclic voltammretry (CV). The characterization of LDH/cMWCNT/PANI/PGE electrode was achieved using electrochemical and scanning electron microscopy (SEM) techniques. The effect of applied potential, pH, lactate concentration, and NAD+ (with and without) on sensor response was assessed. The optimal pH was determined as 7.0. Biosensor response increased with increasing of lactate concentration. The current values were obtained as 0.026 and 0.038 mA cm-2 for 0.166 and 1.331 mM lactate solution with NAD+ as a cofactor, respectively at +0.2 V. The results indicate that LDH/cMWCNT/PANI/PGE biosensor was more sensitive than the biosensor without carbon nanotubes.