Novel La 2 O 3 /g-C 3 N 4 Nanocomposite Electrochemical Immunosensor for Sensitive Detection of Alpha-Fetoprotein in Hepatocellular Carcinoma

We report, for the first time, a synergistic La2O3/g-C3N4 (LCN) nanocomposite used in the development of an electrochemical immunosensor for the highly sensitive detection of alpha-fetoprotein (AFP), an important biomarker for hepatocellular carcinoma (HCC). HCC accounts for over 80–90% of liver cancer cases and often escapes early diagnosis, especially in low-resource settings. To address this clinical need, we present a cost-effective, novel, and synergistic LCN nanocomposite-based electrochemical immunosensor for highly sensitive measurement of alpha-fetoprotein (AFP) to facilitate early diagnosis. The hydrothermal synthesis technique was used to prepare the nanocomposite and was characterized by standard techniques, X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Ultraviolet-Visible (UV-Vis) spectroscopy, Field Emission Scanning Electron Microscopy (FESEM), and Energy Dispersive X-ray Spectroscopy (EDS). The sensor was prepared by drop-casting the nanocomposite on a paper electrode, and the electrochemical characteristics of the sensor were evaluated using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Upon AFP antigen–antibody reaction, the sensor showed a wide linear detection range (0.25–500 ng/mL) with a low limit of detection of 0.035 ng/mL. The immunosensor showed good reproducibility and stable performance over three weeks at 4 °C. Overall, this work presents a potentially effective tool for point-of-care liver cancer diagnosis and routine monitoring of AFP levels.