A light-induced self-powered competitive immunosensor for the detection of platelet derived growth factor-BB via an elaborately assembled bioconjugate

A photocatalytic fuel cell (PFC) coupling with competitive immunoassay was designed for self-powered sensing of platelet derived growth factor-BB (PDGF-BB). In the PFC, the effective oxidation of ascorbic acid (AA) on a photoanode under visible light illumination and catalytic reduction of [Fe(CN) 6 ] 3− on a cathode generated electrical output. In order to realize the specific detection of PDGF-BB, the antibody of PDGF-BB (Ab) was immobilized on photoanode to act as the recognition element. Meanwhile, a bioconjugate, PDGF-BB@AuNPs@dopamine–melanin nanosphere, was used as the competitive element of target which could dramatically reduce the output of PFC by blocking the transfer of AA to the photoanode. When the target PDGF-BB coexisted with the bioconjugate, the competitive binding of smaller target molecule with Ab immobilized on photoanode could reduce the binding amount of bioconjugate and induce an elevated output of PFC. Under the optimum condition, the output of PFC was linearly proportional to the logarithm of PDGF-BB concentration from 20 pg mL -1 to 200 ng mL -1 , with a detection limit (3S/N) of 6.2 pg mL -1 . Moreover, the developed self-powered competitive immunosensor was successfully applied to the detection of PDGF-BB in human serum.