Self-powered aptasensing for prostate specific antigen based on a membraneless photoelectrochemical fuel cell

A self-powered aptasensor for prostate specific antigen (PSA) based on a membraneless photoelectrochemical fuel cell (PEFC) with double photoelectrodes was constructed, in which, PSA-binding aptamer was electrostatically immobilized on the KOH-doped g-C₃N₄ modified TiO₂ nanotube arrays (TNA/A-g-C₃N₄/aptamer), which was used as a photoanode, and Fe³⁺-doped CuBi₂O₄ modified indium doped tin oxide (ITO) substrate (ITO/CBFeO) was used as a photocathode. Under visible light irradiation, glucose was photocatalytically oxidized by A-g-C₃N₄ and generated H₂O₂ in situ, which was used as the electron acceptor for ITO/CBFeO photocathode, thus producing a high cell output response with a maximum output power of 133.5 μW cm^-2 and an open circuit potential of 0.98 V. Due to the specific recognition of PSA by the aptamer and the output power decrease of the PEFC caused by the steric hindrance of the captured PSA on the TNA/A-g-C₃N₄, the PEFC could be used as a self-powered aptasensor for PSA with a quantitative range of 0.005-50 ng mL^-1, a low detection limit of 1.3 pg mL^-1 and good selectivity, and has been successfully applied for the analysis of real human serum samples with good precision of the relative standard deviation (RSD) less than 5.6% and good accuracy of the recoveries ranged from 91% to 108%.