Semiautomated Support Photoelectrochemical Immunosensing Platform for Portable and High-Throughput Immunoassay Based on Au Nanocrystal Decorated Specific Crystal Facets BiVO4 Photoanode.

Photoelectrochemical (PEC) measurement has been developed rapidly for bioanalysis in recent years. However, the actual application for most existed PEC bioanalytical systems is still a challenge because the perfect solutions for sensing surface design, high-throughput detection, and portability are lacked. To successfully overcome these limitations and realize accurate, continuous screening and assessing on prognostic indicator of early stage cancer on the spot, an innovative and portable semiautomated support power-free photoelectrochemical (SP-PEC) immunosensing platform consisted with a miniature semiautomatic injection system and digital multimeter (DMM) readout is designed (prostate specific antigen, PSA, was used as the proof-of-concept analyte). Decahedral BiVO4 that decorated with Au nanocrystal on {010} facets (Au-BiVO4) by photodeposition is used as the photoanode materials to produce photocurrent signal under irradiation of micro laser light (5.0 w, λ ≥ 380 nm). The monoclonal anti-PSA capture antibody (mAb1)-functionalized Fe3O4 magnetic nanobeads (mAb1-MN) and glucose oxidase (GOx)/monoclonal detection antibody (mAb2)-conjugated gold nanoparticle (GOx-AuNP-mAb2) are employed as immunosensing probe and signal probe, respectively. The H2O2 as an excellent holes scavenger that in suit generated from GOx oxidization glucose substrate significantly amplifies the photocurrent. The variation of instantaneous current value that registered as the signal of the immunoassay increases linearly with the logarithm of target PSA concentration increasing in a wide range from 10 pg mL-1 to 100 ng mL-1 with a low detection limit (LOD) of 4.0 pg mL-1. The SP-PEC immunosensing platform not only simplifies the assay process, but also improves detecting efficiency. The semiautomatic and portable SP-PEC analysis device allows analysis on spot and high-throughput continuous detection. Additional, we also gain deep insight into the relations between the specific shape as well as Au nanocrystal decoration and PEC activity and speculate the possible enhancement mechanisms of Au-BiVO4. Therefore, the present work not only develops a flexible SP-PEC biosensor platform for rapid and continuous detection, but also provides a possible route for designing high performance photoelectric materials.