Photoelectrochemical immunoassay of carcinoembryonic antigen based on hollow In₂O₃/In₂S₃ nanocolumn

This work presents a split-type photoelectrochemical (PEC) immunoassay platform for ultrasensitive determination carcinoembryonic antigen (CEA) using In2O3/In2S3 nanocolumn as the photoactive matrix. Initially, In2O3/In2S3 nanocolumn with high photocurrent response was obtained by vulcanizing metal-organic framework-derived hollow In2O3 nanomaterials for surface modification. Subsequently, sandwich immunoreactions were conducted utilizing an alkaline phosphatase-labeled secondary antibody that served as a signal pointer. A large amount of ascorbic acid was produced by the biocatalytic reaction, which enhanced the anodic photocurrent of the In2O3/In2S3 nanocolumn-modified electrode. Under optimized conditions, the In2O3/In2S3 nanocolumn-based PEC immunoassay exhibited a promising photocurrent response to the target CEA in the operational scope of 0.02 ng/mL to 10 ng/mL, with a limit of detection of 8.4 pg/mL. Benefiting from the excellent photoelectrochemical response of In2O3/In2S3 nanocolumn to ascorbic acid and the separated detection operation, the constructed PEC immunosensing platform has the advantages of great precision and strong anti-jamming capability, and the detection results are comparable to those of commercial ELISA kits. Collectively, this study not only offered an efficacious semiconducting surface modification strategy to enhance photocurrent response activity, but also offered a novel thought for the sensitive measurement of a marker of cancer.