SIO2/G-C3N4 NANOCOMPOSITE-ENABLED IMMUNOSENSOR PLATFORM FOR HIGH-FIDELITY ELECTROCHEMICAL DETECTION OF ALPHA-FETOPROTEIN

Abstract

A selective and highly sensitive electrochemical AFP immunosensor was developed using SiO₂/g-C₃N₄ nanocomposite as the sensing element․ α-fetoprotein (AFP) is widely known as a biomarker for the early clinical diagnosis of liver cancer․ The SiO₂/g-C₃N₄ was synthesized by the hydrothermal method, and the crystallinity, chemical bond, optical property, morphology, and composition of the prepared composite were studied using X-ray diffraction (XRD), Fourier transform infra-red (FTIR), UV-Vis, scanning electron microscope (SEM) and energy-dispersive spectroscopy (EDS)․ The high density of active sites on the nanocomposite allows stabilize binding of the anti-AFP antibody, and the binding of AFP with the anti-AFP antibody, results in immune complex layer formation on the electrode's surface․ The electrochemical performance of SiO₂/g-C₃N₄ nanocomposite was examined thoroughly, along with the electrochemical response signals following the immune reaction between AFP and its antibody. The proposed immunosensor exhibited a linear response to lgc_AFP within the concentration range of 0․25-500 ng/mL with a detection limit of 0․0024 ng/mL․The developed immunosensor showed high reproducibility and retained more than 92.6% of the initial response after storage for 28 days at 4°C. The immunosensor developed has great potential for clinical application and further development in the area of hepatocellular carcinoma (HCC) monitoring.