Highly sensitive and selective electrochemical detection of lipocalin 2 by NiO nanoparticles/perovskite CeCuOx based immunosensor to diagnose renal failure.

The early detection of lipocalin 2 (LCN 2), a biomarker to diagnose acute kidney injury (AKI) and its consequences leading to renal failure, is highly challenging due to the lack of proper investigating tools. To overcome this issue, we developed nickel oxide nanoparticles modified cerium copper oxide (NiO Nps/CeCuOx) thin film-based immunosensor to determine the presence of LCN 2 in the analyte. The sol-gel deposited CeCuOx (on a silicon (Si) substrate) was post-annealed at different temperatures (700 °C, 800 °C, and 900 °C), where 800 °C showed the optimum electrochemical performance. NiO nanoparticles, prepared by co-precipitation method, were coated on the pre-silanized CeCuOx to obtain the NiO Nps/CeCuOx/Si electrode. The fast electron transfer, excellent redox property, and high surface-to-volume ratio of NiO Nps/CeCuOx based sensing electrode facilitate the successful immobilization of anti-LCN2 by carbodiimide coupling. The structural, compositional, and stoichiometric properties of the electrode were evaluated by X-ray diffraction, field emission scanning electron microscopy, X-ray photoelectron spectroscopy, high-resolution transmission electron microscopy, and ultraviolet-visible spectroscopy. The immunosensor achieved a significantly low limit of detection (LOD) of 4.23 ng ml-1 for an acceptable linear range of 25-400 ng ml-1 in voltammetric measurement. The device showed high selectivity compared to other related biomolecules. The excellent recovery rates in human serum spiked with LCN2 confirmed the feasibility of the biosensor to use in the actual clinical samples. Therefore, the NiO Nps/CeCuOx/Si based LCN2 immunosensor paves a new route to diagnose kidney-related end-stage diseases.