Rationally Designed Fluorescence (OH)-O-center dot Probe with High Sensitivity and Selectivity for Monitoring the Generation of (OH)-O-center dot in Iron Autoxidation without Addition of H2O2

The first sensitive fluorescence (OH)-O-center dot probe (1) that is capable of monitoring the generation of trace (OH)-O-center dot in iron autoxidation is presented. The probe 1 was designed by utilizing both the unique aromatic hydroxylation and the electrophilicity of (OH)-O-center dot, and prepared by incorporating a strong electron-donating methoxy group into a cyanine fluorochrome to enhance the trapping ability for (OH)-O-center dot. Reaction of 1 with (OH)-O-center dot leads to a larger pi-conjugation formation and near-infrared fluorescence off-on response. The capability of probe 1 has been demonstrated by imaging (OH)-O-center dot generated in living cells under iron autoxidation as well as various stimuli, which reveals that the basal level of (OH)-O-center dot in RAW 264.7 cells is lower than that in HeLa cells. The superior analytical performance of probe 1 makes it useful for detecting trace (OH)-O-center dot in some critical physiological and pathological processes associated with iron autoxidation.