Photoelectrochemical immunosensor for N-methyladenine detection based on Ru@UiO-66, BiO and Black TiO.

A novel photoelectrochemical (PEC) immunosensor was successfully constructed for N-methyladenine (mA) detection based on the photoactive materials of black titanium dioxide (B-TiO) and bismuth trioxide (BiO) and the signal amplification unit of [Ru(bpy)]-doped metal organic framework (MOF). The BiO/B-TiO/ITO electrode was first fabricated, then decorated with gold nanoparticles (AuNPs) which provided sites for anchoring mA antibodies. After the capture of mA via immunoreaction with the antibody, the Zr-based metal organic framework (UiO-66)-[Ru(bpy)] compound was further attached specifically to the phosphate group of mA. 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 mA in rice seedling leaves that had been subjected to heavy metal treatment during their development.