Au-Ag alloy nanoparticle-induced hot electron injection enhances photoelectrochemical detection of alpha-fetoprotein

Early and accurate detection of alpha-fetoprotein (AFP) is critical for the diagnosis and monitoring of hepatocellular carcinoma and other malignancies, However, conventional immunoassays often suffer from limited sensitivity, narrow dynamic range, and complex sample preparation. In this study, we developed a photoelectrochemical (PEC) biosensor based on Au Ag alloy nanoparticles/TiO 2 /Au (AATA) nanocomposite films, which exhibits low background noise and exceptional sensitivity for the quantitative detection of AFP. AATA nanofilms with varying component ratios were fabricated via a combination of magnetron sputtering and spin coating. The synergistic effect of localized surface plasmon resonance (LSPR) from noble metals, plasmonic coupling between the Au film and alloy nanoparticles, and the enhanced hot electron injection efficiency of Au Ag alloy nanoparticles (Au Ag ANPs) significantly improved the PEC performance of the electrode, leading to enhanced photocurrent signals. Under optimized conditions, The PEC biosensor showed a linear response between the photocurrent change and the logarithm of C AFP in the range of 0.1 ng/mL to 1000 ng/mL, with a detection limit as low as 4.54 pg/mL. Additionally, the fabricated biosensor demonstrated excellent sensitivity, stability, and reproducibility, providing a promising analytical platform for the clinical detection of AFP in human serum.