A novel ratiometric and colorimetric chemosensor for highly sensitive, selective and ultrafast tracing of HClO in live cells, bacteria and zebrafish.

Hypochlorous acid (HClO) along with its ionic form, hypochlorite anion (ClO) are critical reactive oxygen species (ROS), which play vital roles in biological systems. Dysregulated production of HClO/ClO can result in tissue damage and cause a variety of diseases. Besides, Sodium hypochlorite has been widely used as a bleaching agent for water disinfection, surface cleaning in daily life. Excessive exposure to sodium hypochlorite will lead to symptoms of severe breathing and skin problems. Therefore, developing a state-of-the-art (simple, highly sensitive, highly selective and super fast-response) sensor for tracking HClO is of biological, toxicological, and environmental importance. Though many HClO probes have been reported so far, this big aim still presents a challenge. Researchers around the world are continuing to develop new HClO probes that could improve their sensitivity, selectivity, the limit of detection, response time, easiness to use, etc. Herein, with coumarin as the fluorophore molecule, we rationally developed a novel chemosensor (CMTH) for detecting HClO with both ratiometric and colorimetric responses resulted from the oxidation reaction of CN bond. Further analysis results indicated that CMTH can realize highly sensitive with low limit of detection (256 nM, among the best of its kind) and highly selective (over a bunch of interfering analytes) imaging detection of HClO in multiple organisms with low cytotoxicity, and good cell and tissue permeability as well. In particular, compared to other fluorescent HClO probes reported so far, CMTH excels in the response time to HClO (< 40 s), being the top-notch of its kind. Besides, owing to its excellent water solubility, CMTH can also be applied to track HClO in the environmental system. Taken together, we have presented here a novel chemosensor, CMTH, as a colorimetric and ratiometric chemosensor for highly sensitive and ultrafast imaging detection of HClO in aqueous solutions, eukaryotic cells, prokaryotic bacteria and vertebrate zebrafish.