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

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 12 kΩ μM(-1) over a wide linear range (0.018-0.5 μM) 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.