Enhanced photocurrents for photoelectrochemical immunoassay of alpha-fetoprotein with Pt-functionalized BiOS nanoflowers.

Background: Designing heterojunctions with efficient electron-hole separation holds great promise for improving photoelectric response.

Results: Herein, we reported a multifunctional Pt co-catalyst-modified BiOS nanoflowers (BOS NFs) photocatalytic component for achieving an efficient photoelectric chemistry (PEC) immunosensor for alpha-fetoprotein (AFP). Briefly, the Pt co-catalyst improved the intrinsic band gap structure of BOS on the one hand, and on the other hand, it was able to achieve a rapid decomposition of hydrogen peroxide to hydroxyl radicals, which led to the improvement of electrochemical half-responses during the amplification of target immunosignals. In addition, Pt-functionalized BOS NFs (BOS-Pt) exhibited peroxidase-like enzymatic reaction activity and related properties. By enzyme-linked immunosorbent assay, a sandwich immuno-model in the presence of AFP catalyzed the production of hydrogen peroxide from the substrate glucose and the conversion of a sizable photoelectrochemical signal catalyzed by BOS-Pt. Following condition optimization, it was determined that the developed sensor exhibited a specific response to AFP over a wide linear range of 0.05-50 ng mL.

Significance: This work provides a new strategy for developing efficient immunosensors from the perspective of modulating photoelectrochemical half-reactions.