Realization of a label-free electrochemical immunosensor for detection of low density lipoprotein using NiO thin film

Abstract

A label-free electrochemical immunosensor, based on nickel oxide (NiO) thin film, for the detection of low density lipoprotein (LDL) has been proposed. P-type semiconducting NiO thin film was deposited by RF sputtering technique and its properties were investigated by X-ray diffraction and Fourier transform infrared spectroscopy. The NiO thin film was utilized as an efficient matrix for the covalent immobilization of apolipoprotein B-100 antibody using EDC/NHS chemistry. The immunoelectrode, thus prepared, was studied using differential pulse voltammetry, cyclic voltammetry and electrochemical impedance spectroscopy. The impedimetric response of the immunosensor exhibited a high sensitivity of 12kΩμM−1 over a wide linear range (0.018–0.5μM) of LDL. The long shelf life (18 weeks) and enhanced performance characteristics of the immunosensor demonstrate the excellent ability of the NiO matrix for quantification of LDL at commercial level.