Methylthio-substituted coumarin-based fluorescent probe for highly specific and fast detection of hypochlorite and bioimaging application

Hypochlorite is a kind of endogenously produced reactive oxygen species (ROS) in the human immune system and plays a crucial role in many pathophysiological processes. In this work a novel fluorescent probe derived from 6-methylthio coumarin was designed and synthesised for detection of hypochlorite in acetonitrile/phosphate-buffered saline (MeCN/PBS) (1:1, v/v, pH 7.4) medium. The probe displayed high specificity toward hypochlorite over other ROS analytes, rapid response to hypochlorite within 30 s, and a broad applicable range of pH 3–8. The detection limit was calculated to be 1.48 μM. Application of this probe for in vitro Hecat cell imaging to detect hypochlorite ions was confirmed. A sensing mechanism based on thioether to sulfoxide oxidation by hypochlorite was proposed and demonstrated. The study presented an effective approach for construction of highly efficient hypochlorite chemosensors from hydrophilic methylthio-substituted coumarins considering their facile access.