Photoelectrochemical immunosensor for N6-methyladenine detection based on Ru@UiO-66, Bi2O3 and Black TiO2

A novel photoelectrochemical (PEC) immunosensor was successfully constructed for N-6-methyladenine (m(6)A) detection based on the photoactive materials of black titanium dioxide (B-TiO2) and bismuth trioxide (Bi2O3) and the signal amplification unit of [Ru(bpy)(3)](2+)-doped metal organic framework (MOF). The Bi2O3/B-TiO2/ITO electrode was first fabricated, then decorated with gold nanoparticles (AuNPs) which provided sites for anchoring m(6)A antibodies. After the capture of m(6)A via immunoreaction with the antibody, the Zr-based metal organic framework (UiO-66)-[Ru(bpy)(3)](2+) compound was further attached specifically to the phosphate group of m(6)A. With visible light irradiation, a large and stable photocurrent response was produced in the presence of ascorbic acid (AA). Under optimized experimental conditions, the linear range of the PEC biosensor was 0.05-30 nM, with a low detection limit of 0.0167 nM (S/N = 3). This method showed high specificity, selectivity, stabilization and repeatability. Moreover, it was successfully used for the detection of m(6)A in rice seedling leaves that had been subjected to heavy metal treatment during their development.