Rapid and sensitive detection of endogenous HClO in living cells and zebrafish using a phenothiazine-based fluorescent probe

Hypochlorous acid (HClO) is a reactive oxygen species (ROS) that plays a critical role in numerous pathological and physiological processes. Abnormal concentrations of HClO in vivo have been closely linked to many diseases, including inflammatory disorders and cancer. In this work, an on-off fluorescent probe PTZ based on phenothiazine was synthesized for specific detection of HClO. PTZ demonstrated excellent selectivity, biocompatibility, rapid response, pH stability, and low limits of detection (5.2 nM). Furthermore, PTZ can detect both exogenous and endogenous HClO rapidly in living cells and zebrafish, which provides it with broad potential applications in life sciences.