Selective visualization of hypochlorite and its fluctuation in cancer cells by a mitochondria-targeting ratiometric fluorescent probe

Hypochlorous acid (HOCl)/hypochlorite (ClO − ), an endogenous reactive oxygen species (ROS), plays an important role in a variety of physiological and pathological processes. Herein, a ratiometric fluorescent probe ( BIP ) for ClO − was prepared, which exhibited a noticeable color change from purple-red to colorless along with a remarkable fluorescence change from bright red to blue in response to ClO − . The probe could quantitatively determine the concentrations of ClO − with large Stokes shift (107 nm), excellent selectivity, fast response, as well as low limit of detection (182 nM). NMR and mass spectral analysis demonstrated that ClO − triggered the oxidative cleavage of the bridge double bond in BIP , resulting in significant changes in color and fluorescence. In particular, BIP was a specific mitochondria-targeted fluorescent probe with excellent photostability, biocompatibility and cell membrane permeability. BIP was successfully used to image intracellular ClO − and its fluctuation in living HeLa cells (human cervical cancer). Furthermore, the probe was employed to visualize the ClO − mediated redox equilibrium within living cells by a ratiometric fluorescence imaging manner. Therefore, BIP has a great potential application for the detecting HOCl, which also offers an effective tool for the investigation of some HOCl related biological processes.