Development of a near-infrared fluorescent probe for visualizing of hypochlorous acid in vitro and in vivo.

Hypochlorous acid (HClO) played momentous role in various physiological processes and the aberrant expression of HClO was related to kinds of diseases including inflammation and cancer. Therefore, optical tracking of HClO was of significance for exploring its physiological and pathological effects. In this study, we designed and synthesized a new near-infrared (NIR) fluorescent probe (TMNDN) for the detection of HClO. Attributed to the robust electron-withdrawing performance of recognition moiety 2,4-dinitroaniline, the ICT process of fluorophore was interrupted and the fluorescence was switched off. Once reacted with HClO, the donor-π-acceptor (D-π-A) structure of the fluorophore was recovered, followed by the enhancement of the NIR fluorescence with a large Stokes shift. The TMNDN exhibited glorious selectivity toward HClO and was successfully applied for visualizing endogenous and exogenous HClO fluctuations in living HeLa and RAW264.7 cells, respectively. Moreover, the noninvasive visualization of endogenous HClO was further achieved in inflammatory bowel disease (IBD) and drug-induced liver injury (DILI) disease mice models in vivo. These above consequences demonstrated that TMNDN could acted as a reliable and promising tool for diagnosis and therapy of HClO-related diseases.