An ultrasensitive immunosensor of Cys/Au@TiO 2 based on disposable screen-printed electrodes (SPE) for PIVKA-II detection for hepatocellular carcinoma (HCC) diagnosis was developed by utilizing Cystine (Cys) and nanocomposite Au@TiO 2 . Firstly, HAuCl 4 underwent a reduction reaction with NaBH 4 , then Au nanoparticles were coated onto TiO 2 nanoparticles. Followed, Cys/Au@TiO 2 was formed through self-assembly of cysteine to allow the monoclonal antibody of abnormal thrombospondin to bound to the amino group on the surface of the composite by covalent bonding. The mechanism is to determine the changes in the current of the sensor caused by the specific binding of the abnormal prothrombin monoclonal antibody adsorbed by the complex with its antigen. The Cys/Au@TiO 2 immunosensor was fully characterized by various analytical approaches and it showed a wide linear testing range of 1–10000 pg mL −1 (R 2 = 0.991) and the limit of detection down to 0.77 pg ml −1 , with highly sensitivity and specificity. The results showed that the developed immunosensor platform can effectively detect trace amounts of PIVKA-II protein and has potent clinical application for HCC diagnosis.
Achieving consistent fabrication of photoelectrochemical (PEC) biosensors remains a challenge, largely due to the variability introduced by manual drop-casting of photoactive materials. To address this limitation, we report a one-step laser-sputtering technique that enables the construction of a standardized sensing platform for ultrasensitive detection of Protein Induced by Vitamin K Absence or Antagonist-II (PIVKA-II), a clinically relevant biomarker for hepatocellular carcinoma. In this process, a mixed target of titanium and melamine is irradiated, where laser-induced thermal and photon pressure effects simultaneously synthesize a TiO 2 /g-C 3 N 4 heterojunction and uniformly sputter-deposit it onto an ITO electrode. This laser-engineered photoanode exhibits excellent batch-to-batch consistency. After immobilizing anti-PIVKA-II antibody, the resulting immunosensor quantifies PIVKA-II based on the specific immunocomplex-triggered photocurrent decrease, achieving a wide linear range from 0.5 ng/mL to 1 μg/mL and a low limit of detection (LOD) of 0.13 ng/mL with high specificity, stability, and reproducibility. Beyond offering a dependable tool for clinical PIVKA-II analysis, this work establishes a generalizable laser-based manufacturing strategy that paves the way toward standardized production of next-generation PEC biosensors.
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