A signal amplification strategy based on hexametaphosphate-stabilized BiVO4@CdS heterojunction with Mg2+-modulated surface charge for CEA detection

Abstract

An ultrasensitive sensor with excellent photoelectrochemical (PEC) properties was developed based on the combination of electrostatic interactions between the hexametaphosphate (HMP)-coated BiVO4@CdS novel photoelectric material and the electron donor. Compared with the conventional BiVO4@CdS photoactive material, the HMP-modified BiVO4@CdS not only increases the stability, but also utilizes the electrostatic interactions between the negative charge carried by the phosphate group and the electron donor, which results to a significant increase in the photoelectric conversion ability after Mg2+ incubation. Specifically, carcinoembryonic antigen (CEA)-targeted immunorecognition was combined with MgCO3 antibody labelling inspired by the ability of HMP to complex with Mg2+. The released Mg2+ from the MgCO3 tag could neutralize the negative charge on the surface of BiVO4@CdS-HMP, and the electrostatic repulsion with the electron donor was suppressed, accelerating the electron transfer, and thus improving the electron-hole separation efficiency. A sensitive detection capability was demonstrated with CEA as the model target. Featuring a wide linear detection range with a detection limit as low as 60 fg/mL, this work provides a fresh perspective on the development of high-performance PEC biosensors.