Titanium Dioxide Nanotube-Based Immunosensor for the Early Detection of the Liver Cancer Biomarker Des-γ-Carboxy Prothrombin (DCP)

Liver cancer remains a leading cause of cancer-related mortality worldwide, with hepatocellular carcinoma (HCC) as the most prevalent form. Des-γ-carboxy prothrombin (DCP) has emerged as a more reliable biomarker than alpha-fetoprotein (AFP) due to its higher specificity. This study presents a titanium dioxide (TiO2) nanotube-based immunosensor functionalized with DCP antibodies for proof-of-concept label-free capacitive detection of the liver cancer biomarker DCP. Field-emission scanning electron microscopy (FESEM) analysis revealed a more uniform TiO2 nanotube-like morphology after 2-h anodization, with apparent pore diameters of approximately 120–150 nm based on scale-bar estimation. The immunosensor demonstrated a strong linear response across DCP concentrations (3.125–2000 ng/mL), with optimal performance at 1068 Hz, a coefficient of determination (R2) > 0.95, a limit of detection (LOD) = 3.30 ng/mL, and high reproducibility with a coefficient of variation (CV) of 1.64%. To the best of our knowledge, this is the first report of a TiO2 nanotube-based label-free capacitive immunosensor for DCP detection.