Design,Synthesis And Biological Application Of A Novel Fluorescent Dye

The combination of fluorescent probes and fluorescent imaging technology has eminent advantages such as high spatiotemporal resolution,high sensitivity and high selectivity.Therefore,this method has been used extensively in recent years to detect a variety of active molecules in cells and vivo in real time.Cysteine(Cys),as an effective antioxidant,plays a crucial role in redox homeostasis and regulates multiple physiological processes.Hypochlorous acid(HOCl)and hydroxyl radicals(·OH)are tipical representatives of the reactive oxygen species(ROS).Various diseases are highly related to the abnormal concentrations of HOCl and ·OH in cells which can also result in dramatic changes of intracellular microenvironment such as viscosity.Both of them play an extremely significant role in maintaining the dynamic balance of intracellular redox,so the detection of these active molecules by fluorescent probes has great application value in the fields of medical and clinical diagnosis.Nevertheless,conventional fluorescent probes(dye)such as fluorescein,rhodamine and cyanine usually exhibit either small Stokes shifts of less than 30 nm or low quantum yields.Therefore,it is particularly important to design and synthesize novel fluorescent probes possessing the traits of large Stokes shift,high quantum yield and red / near infrared emission simultaneously for real-time and quantitative detection of active molecules in biological systems.The main results of this dissertation are shown as follows:1.We have designed and synthesized a novel dye: The introduction of two nitrogen-containing heteroatoms and five-membered pyrrolidine into the dye can increase the Stokes shift and fluorescence quantum yield simultaneously,and access groups that can change the water solubility.The interaction with analyte will transform the reaction site anticipated by us into a hydroxyl group which can further be utilized to form closed ring.And then the extended conjugate structure successfully induces bathochromic shift of the spectrum and stronger fluorescence emission.2.We have designed and synthesized a novel probe(HN-1)for intracellular cysteine imaging with high fluorescence quantum yield and large Stokes shift.The fluorescent probe uses acryloyl chloride as the recognition site which responds to cysteine with high selectivity.In addition,the fluorescent probe emits at 616 nm and displays intensive red fluorescence.3.We have designed and synthesized an excellent fluorescent probe for detecting hypochlorous acid with high selectivity in living cells and zebrafish.The fluorescent probe has a highly specific response to hypochlorous acid.In addition,the probe exhibits excellent performances including good water solubility,high fluorescence quantum yield,large Stokes shift,wide linear range,good photostability and conspicuous phenomenon.4.We have designed and synthesized a dual-channel fluorescent probe for simultaneous differentiation and detection of hydroxyl radicals and viscosity.For the first time,this probe uses the malononitrile moiety as the recognition module which responds quickly to hydroxyl radicals(?ex / ?em = 430/500 nm).In addition,the probe also has a good response to viscosity(?ex / ?em = 470/602 nm).Futhermore,the excellent probe owns admirable features such as high fluorescence quantum yield,large stokes shift and the product also with good water solubility.