A benzothiazole-based fluorescent probe for hypochlorite – highly sensitive detection and live-cell imaging research

Hypochlorous acid (HOCl), a key reactive oxygen species, is generated <i>in vivo</i> through the catalytic action of myeloperoxidase and plays a crucial role in innate immunity. However, dysregulation of HOCl levels can contribute to the development of various diseases. Due to its high reactivity, short lifespan, and limited diffusion distance in biological systems, real-time tracking of HOCl presents significant challenges. In this study, we have successfully designed and synthesized a novel fluorescent "turn-on" probe, BZDC, based on benzothiazole derivatives. The probe exhibits exceptional sensitivity for detecting OCl^-, with a detection limit as low as 0.953 µM, and demonstrates excellent selectivity. A distinct color change from colorless to light yellow is observed in the solution during detection. The response mechanism of BZDC to OCl^- was elucidated through various experimental techniques, including UV-Vis absorption spectroscopy, fluorescence titration, NMR titration, and mass spectrometry. Furthermore, BZDC exhibits low cytotoxicity and has been successfully applied to image OCl^- in living cells. These findings provide valuable insights for the future development of hypochlorite sensors for a range of chemical and biological applications.