An Ultrasensitive Cyclization-Based Fluorescent Probe for Imaging Native HOBr in Live Cells and Zebrafish

Bromine has been reported recently as being the 28(th) essential element for human health. HOBr, which is generated in vivo from bromide, is a required factor in the formation of sulfilimine crosslinks in collagen IV. However, to date, no method for the specific detection of native HOBr in vivo has been reported. Herein, we develop a simple small molecular probe for imaging HOBr based on a specific cyclization catalyzed by HOBr. The probe can be easily synthesized in high yield through a Suzuki cross-coupling reaction. The probe exhibits ultrahigh sensitivity at the picomole level, in addition to specificity for HOBr and real-time response. Importantly, without Br(-) stimulation, this probe reports native HOBr levels in HepG2 cells. Thus, the probe is a promising new tool for imaging endogenous HOBr and may provide a means for finding new physiological functions of HOBr in living organisms.