Hypochlorous acid turn-on boron dipyrromethene probe based on oxidation of methyl phenyl sulfide

•A BODIPY-based green fluorescent probe for sensing HOCl was developed.•The probe utilizes HOCl-promoted oxidation of methyl phenyl sulfide to produce a proportional fluorescence response to the concentration of HOCl.•Confocal fluorescence microscopy imaging of RAW264.7 cells demonstrated that the HCS probe might have application in the investigation of HOCl roles in biological systems. A boron dipyrromethene (BODIPY)-based fluorometric probe, HCS, has been successfully developed for the highly sensitive and selective detection of hypochlorous acid (HOCl). The probe is based on the specific HOCl-promoted oxidation of methyl phenyl sulfide. The reaction is accompanied by a 160-fold increase in the fluorescent quantum yield (from 0.003 to 0.480). The fluorescent turn-on mechanism is accomplished by suppression of photoinduced electron transfer (PET) from the methyl phenyl sulfide group to BODIPY. The fluorescence intensity of the reaction between HOCl and HCS shows a good linearity in the HOCl concentration range 1–10μM. The detection limit is 23.7nM (S/N=3). In addition, confocal fluorescence microscopy imaging using RAW264.7 macrophages demonstrates that the HCS probe could be an efficient fluorescent detector for HOCl in living cells.