Single-atom Pt-anchored Zn0.5Cd0.5S boosted photoelectrochemical immunoassay of prostate-specific antigen

Photoelectrochemical immunoassays/immunosensors have been employed for biomarker detection, but most are lack of high-efficiency photo-electron transfer nanomaterials for widespread utilization. Herein we synthesized single-atom platinum-anchored Zn0.5Cd0.5S nanostructures to construct an innovative photoelectrochemical (PEC) immunosensor for photocurrent determination of prostate-specific antigen (PSA). Improvement of the photocurrent on the sensing interface derived from the ion-exchange reaction between cupric oxide nanoparticle (CuO NP)-labeled secondary antibody and single-atom platinum-anchored Zn0.5Cd0.5S. The experimental results showed that the doping of zinc ions and atomically dispersed platinum into CdS could significantly enhance the photocurrent, which further improved the sensitivity of immunoassay. Specifically, upon sensing the target PSA, a CuO-labeled detection antibody was introduced by sandwich immunoreaction and numerous copper ions (Cu2+) were released from CuO by acid to participate in the ion-exchange reaction. Thereafter, the ion-exchange reaction between Cu2+ ions and single-atom platinum-anchored Zn0.5Cd0.5S resulted in the quenching of the photocurrent from single-atom platinum-anchored Zn0.5Cd0.5S owing to weak photoactive material CuxS formation. Under optimized conditions, single-atom platinum-anchored Zn0.5Cd0.5S-based photoelectrochemical immunoassay gave good PEC signals toward PSA from 1.0 to 10000 pg/mL with a limit of detection of 0.22 pg/mL. Additionally, good repeatability, intermediate precision, strong anti-interference and high accuracy (relative to commercialized ELISA kit) for the measurement of human serum specimens were acquired. Importantly, use of single-atom platinum-anchored Zn0.5Cd0.5S can provide an important idea for early tumor screening and diagnosis.