A novel near-infrared fluorescent probe based on phenoxazine for the specific detection of HOCl

Among the diverse reactive oxygen species (ROS), hypochlorous acid (HOCl) plays an essential role in various biological processes. However, superfluous or uncontrollable hypochlorous acid can result in tissue damage and trigger a series of inflammation-associated diseases. Therefore, it is greatly urgent to develop highly efficient fluorescent probes for the detection of HOCl. Here, a novel near-infrared (NIR) fluorescent probe BR-1 is designed and synthesized through connecting N,N-dimethyl-thiocarbonyl (DMTC) group to the phenoxazine skeleton via one-pot approach to sense and image HOCl. Although DMTC exhibits significant sensitivity and fast response towards HOCl, it suffers from great interference from Hg2+ owing to the existence of sulfur atom. Interestingly, the probe BR-1 displays excellent anti-interference against Hg2+ when DMTC is linked to the phenoxazine skeleton. In addition, BR-1 shows quick response, high sensitivity and selectivity towards HOCl both in vitro and in vivo. Moreover, BR-1 is capable of rapidly detecting and imaging endogenous HOCl in the inflammation area from the mouse models of arthritis.