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.