High-entropy effect with hollow (ZnCdFeMnCu)_xS nanocubes for photoelectrochemical immunoassay

High entropy (HE) compounds with chemically disordered multi-cation structures have become a hot research topic because of their fascinating "cocktail effect". However, high entropy effect with the efficient photoelectric response has not been reported for photoelectrochemical (PEC) immunoassays. Herein, an innovative PEC immunoassay for the sensitive detection of prostate-specific antigen (PSA) was ingeniously constructed using hollow nanocubic (ZnCdFeMnCu)_xS photoactive matrices with high entropic effect via the cation exchange. Initially, a sandwich-type immunoreaction has behaved using dopamine-loaded liposome labeled with anti-PSA secondary antibodies. In the presence of PSA, addition of Triton X-100 caused the liposomal cleavage to release dopamine, which was then detected as a reduced photocurrent on (ZnCdFeMnCu)_xS-based photoelectrode. Under optimal condition, the PEC immunoassay showed good photocurrent responses toward target PSA with the dynamic linear range of 0.1-50 ng mL^-1 with a limit of detection of 34.1 pg mL^-1. Significantly, this system can provide a new platform for the development of PEC immunoassays by coupling with high-entropy photoactive materials.