Water‐Soluble Squaraine‐Based NIR Chromofluorogenic Probe for HClO/ClO− Detection in Environmental Waters and Live‐Cell Bioimaging

Abstract Hypochlorous acid/hypochlorite (HClO/ClO − ), as critical biological reactive oxygen species (ROS), plays essential roles in numerous physiological and pathological processes. To enable sensitive detection of HClO/ClO − in environmental water samples and living cells, a near‐infrared (NIR) water‐soluble squaraine‐based chromofluorogenic probe SO 3 SQ was developed. SO 3 SQ exhibits good water solubility, NIR detection wavelength (696 nm/725 nm), high selectivity, rapid response time (within seconds), visible colorimetric response, and minimal cytotoxicity. Furthermore, SO 3 SQ achieved quantitative HClO/ClO − detection in environmental water samples and realized real‐time fluorescence imaging of exogenous/endogenous HClO/ClO − in HepG2 cells. This work provides new ideas for the future design of NIR water‐soluble HClO/ClO − probes, while expanding the application of squaraine dyes as HClO/ClO − probes.