Construction and application of a coumarin-based fluorescent probe for hypochlorous acid

Hypochlorous acid (HClO/HOCl) is a reactive oxygen species closely associated with immune defense and oxidative stress-related pathology, creating demand for fast and convenient analytical tools for its detection in environmental and biological matrices. Herein, a coumarin-derived fluorescent probe (XDS) was synthesized by condensing a coumarin aldehyde with a benzothiazolium salt. XDS exhibited an obvious color change (purple to colorless) and a turn-on fluorescence response toward HClO in a DMSO/PBS (3 : 7, v/v, pH 7.4) system. Under optimized conditions, XDS exhibited high selectivity against common anions, biothiols, and several reactive oxygen/nitrogen species, and reached its fluorescence plateau within ∼15 s after HClO addition. The probe was further integrated into a solid support format by loading it onto silica gel plates, enabling visual readout for HClO-spiked tap water, stream water, and mineral water samples. In addition, XDS was applied to fluorescence imaging of exogenous HClO in HepG2 cells and to adult zebrafish imaging following chemical stimulation. These results support the potential of XDS as a rapid dual-mode (colorimetric/fluorescent) platform for HClO sensing in aqueous samples and biological systems.