A ratiometric nopinyl-derived fluorescent probe for detecting hypochlorite (ClO−) with high sensitivity and its application in living biological systems

A ratiometric fluorescent probe was synthesized for detecting hypochlorite based on nopinone. • The optical properties and detection performances of the probe were studied comprehensively. • The nopinyl-based chemosensor exhibits excellent capability and was applied in bioimaging. Hypochlorous acid (HOCl)/hypochlorite (ClO − ), an endogenous reactive oxygen species (ROS), plays a major part in physiological and pathological processes. The nopinone derivatives have been proved to be a good fluorophore scaffold and applied for the detection of multiple analytes, which benefited from its natural product properties, good biocompatibility, modifiability, and good photochemical properties. Herein, a ratiometric fluorescent probe ( NPBM ) for detecting ClO − was designed, which exhibited a remarkable fluorescence change from yellow to cyan in response to ClO − . The probe could quantitatively determine the concentrations of ClO − with excellent selectivity, fast response time, as well as low limit of detection (0.266 μM). High resolution mass spectral analysis demonstrated that ClO − triggered the oxidative cleavage of the bridge double bond in NPBM , resulting in significant change in fluorescence. In particular, benefiting from favorable biocompatibility and efficient cell-membrane permeability, NPBM has been successfully applied for ratiometric fluorescence imaging of exogenous ClO − in living HeLa human cervical cancer cells and zebrafish models. Such superior comprehensive performance endows NPBM with promising prospects for ClO − detection in complex biological systems. Therefore, NPBM has a potential application for the development of tools for detecting ClO − .