Phenothiazine-Hemicyanine Hybrid as A Near-Infrared Fluorescent Probe for Ratiometric Imaging of Hypochlorite in Vivo

Ratiometric near-infrared fluorescent probes are powerful tools for studying the biological roles of hypochlorite in biological systems. However, due to the lack of suitable fluorescent molecular platforms, the development of near-infrared ratiometric hypochlorite probes remains a challenge. Here, we report the design and synthesis of a near-infrared fluorescent probe PTZCy, which is constructed using a phenothiazine-hemicyanine hybrid framework. The incorporation of phenothiazine into the hemicyanine scaffold enables the probe to exhibit a near-infrared emission maximum at approximately 820 nm, along with a rapid and highly selective ratiometric response to hypochlorite. Importantly, PTZCy can be used to image both endogenous and exogenous hypochlorite in RAW264.7 cells, as well as to perform ratiometric imaging of hypochlorite during the acute liver injury process in living mice.