A photoelectrochemical platform constructed with C-doped ZnIn2S4 /Bi2S3: Excellent for the visual detection of tumor marker

A photoelectrochemical (PEC) immunosensor based on a novel composite material was proposed for the highly sensitive and selective detection of Alpha-fetoprotein (AFP). C-doped ZnIn2S4/Bi2S3 (ZnIn2S4/Bi2S3/C) nanocomposites were synthesized in one pan by solvothermal method using glucose as carbon precursor and used as photoanode. ZnIn2S4/Bi2S3 displayed efficient visible light utilization and carrier separation efficiency. In addition, the high electrical conductivity of carbon materials also allowed ZnIn2S4/Bi2S3/C to show stronger photocurrent compared to ZnIn2S4/Bi2S3. The PEC sensor was successfully prepared in combination with a selective AFP antibody. The photocurrent decreased with the increase of AFP concentration in the range of 0.001-1000 ng·mL−1, with a calculated detection limit of 0.12 ng·mL−1. Besides, in order to eliminate the workstation's limitations, a colorimetric device that can display AFP levels nearly simultaneously was constructed by modifying Prussian blue on another FTO electrode and connecting the two electrodes by wires. This work provided a new approach for the instant detection of AFP in serum by developing a visualization device for rapid screening and identification of AFP by introducing the electrochromic principle and integrating the device from the viewpoint of improving the practicality of the sensing method.