A sensitive and selective turn-on fluorescent probe for hypochlorous acid based on a thiorhodamine 6G amide, and its application in cellular imaging

We report that a previously found fluorescent chemodosimeter for Hg(II) ions can also be used as a fluorescent probe for hypochlorous acid (HClO) in that its fluorescence intensity (excited at 520 nm and measured at 563 nm) is linearly proportional to the concentration of HClO in the 1-100 mu M range and with a 0.1 mu M detection limit. The probe can detect HClO with virtually no interference by Hg(II) and other metal ions. The mechanism for the high selectivity for HClO has been studied. The probe was applied to image hypochlorite in E. coli cells.