The Synthesis And Application Of Reaction-Based Fluorescent Probes For Hypochlorous Acid

During the past 20 years there has been a remarkable growth in the use of fluoresecence in the biochemistry and biophysics. Fluorescence is now a dominant methodology used extensively in biotechnology, flow cytometry, medical diagnosetics, DNA sequencing, forensics, and genetic analysis, to name a few. Hypochlorous acid (HClO) is an important ROS which is endogenously generated in cellular environments to kill invading bacterial pathogens. Excessive production of HClO, however, leads to the oxidation of biomolecules which results in tissue damage and various diseases such as atherosclerosis, arthritis and cancer. Thus, sensitive and accurate detection probes for hypochlorous acid that function in living sample are highly demanded for the research in biology and environment.In this thesis, two fluorescent probes based on molecular recognition and molecular flurescence sensing principle for hypochlorous acid detection in cells and environment were developed.An aza-coumarin based fluorescent probe AC-CIO was designed and synthesized for the ClO- determination with fast response (completed within 2 min) and high sensitivity (detection limit is 25 nM). AC-CIO displayed a color change from pink to light yellow and a remarkable "turn-on" fluorescence response towards ClO-. Confocal fluorescence microscopy experiments demonstrated that the probe could be applied for the live-cell imaging of exogenous and endogenous ClO-.We used a 3-pyrrole BODIPY dye as a new ratiometric fluorescent probe (BRClO) for HClO. BRClO exhibited a 177-fold fluorescence ratio (F505nm/F585nm) enhancement in the presence of HClO over other ROS with fast response time (completed within 1 s). Confocal fluorescence imaging using BRClO showed separate signals in the presence of exogenous HClO in live cells:the background signal is in the cytoplasm; the target signal is in the plasma membrane. In addition, BRClO could be easily prepared as HClO test strips to detect HClO in aqueous solution and natural tap water.