A Long-wavelength Emissive Phenothiazine Derived Fluorescent Probe for Detecting HOCI Upregulation in 5-FU Stimulated Living Cells

The endogenous hypochlorous acid(HOCI)has been evidenced in a variety of cellular courses.However,the role of HOCI in most pathophysiological processes still keeps unclear because of the limited detecting tools.In this work,we presented the pre-paration of a phenothiazine-derived fluorescent probe CIO-1 for HOCI detection with a cyanopyridinium moiety to improve its water solubility and lengthen its emission wavelength.The HOCI-pro-moted oxidation of sulfur atom in the probe resulted in a 460-fold emission intensity enhancement at 635 nm with high selectivity and sensitivity(detection limit:1.12 nmol/L).The rapid response(5 s)also endowed the probe with real-time detection ability.Success-fully,CIO-1 was devoted to the bioimaging of endogenous HOCI in inflamed RAW 264.7 cells and 5-fluorouracil-treated MCF-7 cells.