Au Nanoparticle-Decorated ZnO Microflower-Based Immunoassay for Photoelectrochemical Detection of Human Prostate-Specific Antigen

Herein, an in situ amplified photoelectrochemical (PEC) immunoassay with ZnO microflowers (ZnO MFs) decorated with gold nanoparticles (Au NPs) was developed to determine human prostate-specific antigen (PSA) using l-cysteine-loaded liposomes for signal amplification. Initially, ZnO MFs with smooth and well-defined morphology were synthesized under hydrothermal conditions. The heterostructured microflowers were formed by depositing Au NPs on ZnO microflowers using trisodium citrate. l-Cysteine (l-Cys)-encapsulated liposomes conjugated with detection antibodies were used to fabricate a sandwiched immunocomplex on a capture antibody-modified microtiter plate in the presence of target PSA. The liposomes were lysed using Triton X-100 to release the encapsulated l-Cys, thereby increasing the photocurrent on Au NP-decorated ZnO MFs. Results indicated that the photoelectrochemical immunoassay displayed good photocurrents to response PSA concentrations from 0.01 to 20 ng mL–1, and the detection PSA concentration was as low as 0.79 pg mL–1. Furthermore, the photoelectrochemical immunoassay had good precision, high selectivity, and well-matched accuracy toward target PSA in human serum specimens using the commercialized human PSA ELISA kit as a reference.