A HClO-specific near-infrared fluorescent probe for determination of Myeloperoxidase activity and imaging mitochondrial HClO in living cells

Hyperchlorous acid (HClO), produced from MPO, is recognized as a host defense that kills pathogens; a signaling molecule that initiates cell apoptosis; and a harmful agent when overproduced. Thus, measuring of endogenous HClO and MPO will always find its great importance in revealing biological roles under complex biological conditions. In this study, a turn-on near infrared (NIR) fluorescent probe Cy7-NphS has been designed and developed for highly selective and sensitive sensing of HClO and Myeloperoxidase (MPO) with fast response time. The newly developed probe has been successfully applied in real-time monitoring of HClO and MPO activity in PBS solutions and living HL-60 cells. When applied in MPO activity determination, the probe showed very high sensitivity with a detection limit of as low as 3.69×10−3 U/mL. Furthermore, the living cell imaging study suggested that this probe could detect HClO in mitochondria.