A novel two-channel ratiometric fluorescent probe for monitoring hypochlorous acid fluctuations in inflammation.

Hypochlorous acid (HClO), as an important member of reactive oxygen species (ROS), is associated with various diseases, including cancer progression and inflammation. Monitoring the dynamic changes of HClO in physiological and pathological processes is significant for the diagnosis of these diseases. Herein, we designed and developed a ratiometric fluorescent probe TCF-MB for the specific detection of HClO. The probe features tricyanofuran (TCF) as a strong electron-withdrawing group, a benzene ring, and a carbon-carbon double bond as the π-conjugation bridge, and n-butyl-substituted phenothiazine as the electron donor and reactive site. TCF-MB exhibits a pronounced intramolecular charge transfer (ICT) effect. After the addition of HClO, the sulfur atom in TCF-MB is oxidized to sulfoxide, resulting in the blue shift of absorption and emission spectra due to the interruption of the ICT effect. TCF-MB displayed excellent sensitivity and selectivity toward HClO with the LOD of 0.23 μM. Furthermore, TCF-MB can effectively monitor both endogenous and exogenous HClO in living cells and inflammatory zebrafish with low cytotoxicity. These results demonstrated that probe TCF-MB could be a robust tool for tracking HClO dynamics in physiological and pathological environments.