Reaction-Based Fluorescent Probe For Hypochlorous Acid

As a kind of reactive oxygen species (ROS), hypochlorous acid (HC10) plays a pivotal role in the immune defense against microorganisms and also in inflammation. In living organisms, hypochlorous acid is produced predominantly from hydrogen peroxide and chloride ions in a chemical reaction catalyzed by the heme enzyme myeloperoxidase (MPO). Maintenance of appropriate concentrations of HClO is essential for numerous cellular function; however, many evidences suggest that once the cells cannot maintain the level within the physiological range, HC1O is engaged in some diseases, such as atherosclerosis, osteoarthritis, rheumatoid arthritis and even cancers.Therefore, a rapid, sensitive and selective detection of HClO in biological samples by fluorescence-based assays is of significant interest.In this thesis, four fluorescent probes based on molecular recognition and molecular fluorescence sensing principle for hypochlorous acid detection in cells and organisms were developed. By modification of BODIPY dye, a classical fluorophore platform, two probes were prepared with the triphenylphosphine as the mitochondria locatable group and C=N, C=C as the reactive sites. Upon addition of sodium hypochlorite to the test system, sodium hypochlorite could induce the broken of C=N and C=C, causing the changes both in color and fluorescence. The two probes enabled fast detection towards hypochlorous acid, no inferences from other ROS and the fast fluorescent imaging of endogenous HClO in mitochondria.A ratiometric fluorescent probe for HClO detection, BODIPYWCHO, was developed by modification of BODIPY dye at the3-position. The emission spectra of BODIPYWCHO centered at the near-infrared region (713nm), and it blue-shifted to511nm after the reaction with HClO. In addition, the ratios of the fluorescence intensity at511and713nm had a good linear relationship between the concentrations of HClO. BODIPYWCHO could respond to HC1O rapidly in the proposed testing system with negligible interference from other ROS.A NIR fluorescent probe (SeCy7) for HClO was developed by introducing selenamorpholine to the meso-position of heptacyanine dye. The introduction of selenamorpholine reinforced the self-aggregation of the dye, and so as to reduce the background fluorescence to a large extent, which makes it possible to detect HClO in pure buffer solution. The recognition process was fast, and had no interference from pH and other ROS. The detection limit of the probe was0.31μM. The probe was able to detect HClO in fetal calf serum, and the exogenous and endogenous sources of HClO in living mice.