Rapid and selective visualization of mitochondrial hypochlorite by a red region water-soluble fluorescence probe

A mitochondria-targeting fluorescent probe (FI-Mito) for −OCl was developed based on rhodamine dye. More importantly, FI-Mito was capable of detecting endogenous −OCl both in RAW264.7 cells and living mouse. [Display omitted] •A novel fluorescent probe for −OCl was developed based on rhodamine dye.•The probe could monitor −OCl changes in the red region.•The probe could target mitochondria with little cytotoxicity.•The probe was applied to image endogenous −OCl in RAW264.7 cells and living mice. Hypochlorite (−OCl) has long been recognized as an effective microbicidal agent in immune system. Herein, we report the design, preparation and spectral characteristics of a −OCl fluorescent probe (FI-Mito). The probe exhibited remarkable fluorescence turn-on signal in the red region upon −OCl titration with the detection limit as low as 0.9 nM. FI-Mito displayed specific response for −OCl in completely aqueous solution. Meanwhile, the introduction of quaternized pyridine realized mitochondria-targeting ability. FI-Mito was further applied to monitor the generation of endogenous −OCl in the mitochondria of macrophage cells and mice. Therefore, it was established that FI-Mito may serve as a useful molecular tool for −OCl detection in vivo.