An electrochemical biosensor with nanointerface for lactate detection based on lactate dehydrogenase immobilized on zinc oxide nanorods

Hepatic immaturity is observed particularly in children whose age is under three, when the lactate concentration is greater than the normal level in blood. An electrochemical lactate biosensor was developed by immobilizing lactate dehydrogenase (LDH) on to ZnO nanorods at pH 7.4 via chitosan. Growth of polycrystalline ZnO nanorods towards (101) plane was confirmed using XRD. The FE-SEM study revealed the formation of ZnO nanorods with an aspect ratio of 3.24. Immobilization of LDH on ZnO nanorods was confirmed using FTIR spectra and surface coverage. Electrochemical studies were carried out through cyclic voltammetry and amperometry using three electrode system with Au/NanoZnO/LDH as working electrode, Ag/AgCl in 0.1 M KCl as reference electrode and Pt wire as counter electrode. The sensitivity of the biosensor was found to be 1.832 mu A mu mol(-1) L exhibiting linearity 0.2-0.8 mu mol L-1 with the detection and quantification limits of 4.73 and 15.75 nmol L-1 respectively. The response time of Au/NanoZnO/LDH bioelectrode was found to be <1 s. Prediction band for net current. was framed to enhance specificity. Michaelis-Menten constant (K-M(app)) and maximum rate (I-max) values for immobilized LDH were found to be 0.38 mu mol L-1 and 2.798 mu A respectively. Repeatability and reproducibility of LDH biosensor were also reported. (C) 2013 Elsevier Inc. All rights reserved.