[Ru(bpy)₃]²⁺@Ce-UiO-66/Mn:Bi₂S₃ Heterojunction and Its Exceptional Photoelectrochemical Aptasensing Properties for Ofloxacin Detection

A photoelectrochemical (PEC) aptasensor on basis of [Ru­(bpy)3]2+@Ce-UiO-66/Mn:Bi2S3 composites was constructed for detecting ofloxacin (OFL). First, Ce-UiO-66, prepared by a solvothermal method, had Zr4+–Zr3+ and Ce4+–Ce3+ intervalence cycles to increase the charge separation efficiency. Subsequently, Ce-UiO-66 was further modified by [Ru­(bpy)3]2+ and Mn:Bi2S3 cosensitization to improve the photoelectric activity. [Ru­(bpy)3]2+ not only broadened the range of light absorbed but also reacted with an electron donor to maintain the photoelectric conversion process. Among the [Ru­(bpy)3]2+@Ce-UiO-66/Mn:Bi2S3 heterojunction, Mn:Bi2S3 was a photosensitizer, which maximized the efficiency of the electron–hole separation and significantly improved photocurrent. Then, an aptamer was used as a biorecognition unit for OFL-specific detection. Under the best conditions, the PEC aptasensor realized the sensitive detection of OFL, with a detection range of 0.01–100 nmol/L and a detection limit of 6 pmol/L. In addition, the constructed PEC OFL sensor showed good reproducibility, stability, and specificity