Self-powered molecular imprinted photoelectrochemical sensing platform of sialic acid employing WO3/Bi2S3 photoanode and CuInS2 photocathode

A dual-photoelectrode molecular imprinted photoelectrochemical (PEC) sensor is first built for the determination of sialic acid (SA) without additional energy supply. Specifically, WO3/Bi2S3 heterojunction behaves as a photoanode to provide amplified and stable photocurrent for the PEC sensing platform, which is attributed to the matched energy levels of WO3 and Bi2S3 promoting the electron transfer and improving photoelectric conversion properties. CuInS2 micro-flowers functionalized by molecularly imprinted polymers (MIPs) are served as photocathode to recognize SA, avoiding the deficiency of high production cost and poor stability from biological enzymes, aptamers, or antigen-antibodies. The inherent deviation between the Fermi level of the photoanode and the photocathode guarantees a spontaneous power supply for the PEC system. Benefiting from the photoanode and recognition elements, the as-fabricated PEC sensing platform has a strong anti-interference ability and high selectivity. Moreover, the PEC sensor displays a wide linear range of 1 nM-100 μM and a low detection limit of 7.1 × 10-10 M (S/N = 3) based on the relationship between photocurrent signal and SA concentration. Accordingly, this research provides a new and valuable approach to detecting various molecules.