Microfluidic photoelectrochemical immunosensor based on BiOCl@au/CdS heterojunction for the trace detection of liver cancer marker.

Rapid and accurate monitoring of vitamin K deficiency or prothrombin induced by vitamin K antagonist-II (PIVKA-II) is crucial for the prevention, diagnosis, and treatment of liver cancer. Here, a novel immunosensor for PIVKA-II detection is proposed by integrating a microfluidic device and a photoelectrochemical sensor. Firstly, BiOCl@Au composite and CdS photoactive material were synthesized using the solvothermal method, then were sprayed onto the laser-etched fluorine-doped tin oxide (FTO) surface, and the formed heterojunction can suppress the recombination of photogenerated electron-hole pairs. The gold nanoparticles, with localized surface plasmon resonance effects, not only enhanced light absorption but also promoted electron transfer. Furthermore, a microchannel fabricated by photolithography was combined with the FTO substrate, and PIVKA-II capture antibodies were modified on the heterojunction surface for the specific capture of PIVKA-II. The microfluidic immunosensor exhibits a good linearity from 0.1 pg/mL to 100 ng/mL, with a detection limit of 0.078 pg/mL (S/N = 3). Additionally, this sensor shows good selectivity, stability, reproducibility, excellent anti-interference ability and reliability in monitoring the trace liver cancer marker PIVKA-II.