Surface plasmon resonance‐enhanced photoelectrochemical immunoassay of prostate‐specific antigen based on BiOCl‐Au heterojunction

Abstract

AbstractTaking advantage of the high‐efficiency photocurrent response of bismuth oxychloride sensitized with gold nanoparticles (BiOCl−Au) in combination with the antigen‐antibody biological recognition reaction, a convenient photoelectrochemical (PEC) immunoassay (model target: prostate‐specific antigen; PSA) has been fabricated. In particular, the enhanced photocurrent response could be attributed to the enhanced optical absorption of visible light from surface plasmon resonance (SPR) effect of gold nanoparticles in the hierarchical structure of BiOCl layered. To realize the biological detection process, an immunoreaction was implemented between target PSA and alkaline phosphatase (ALP)‐labeled anti‐PSA antibodies. With the formation of ternary sandwich immunocomplex, the carried and loaded ALP catalysed the substrate ascorbic acid 2‐phosphate (AAP) to generate ascorbic acid for increasing the photocurrent intensity of BiOCl−Au/FTO. Under optimum reaction time, the photocurrent peak intensity of BiOCl−Au/FTO increased with the increasing of target PSA concentration in the range of 0.01 ng/mL to 50 ng/mL with a limit of detection (LOD) down to 2.3 pg/mL. In the photocurrent control experiment, the photocurrent of BiOCl−Au/FTO was not only higher than that of BiOCl/FTO, but also showed greater changes in photocurrent under the same target PSA concentration. Impressively, the proposed split‐type PEC immunoassay was applied to detect PSA concentration in human serum samples, giving acceptable and satisfactory accuracy compared with the gold standard PSA ELISA method.