Design, Synthesis And Biological Application Of Near-infrared Hypochlorous Acid Fluorescent Probe

Hypochlorous acid(HOCl)is an important reactive oxygen species(ROS)produced by hydrogen peroxide and chloride ions in organism under the catalytic action of myeloperoxidase(MPO).Hypochlorous acid plays an important role in the immune system and in regulating the redox balance of the cellular microenvironment.However,when the level of hypochlorous acid in the cells exceeds the normal range,it will cause the damage of organism and a series of diseases,such as atherosclerosis,arthritis,rheumatoid arthritis,lung inflammation,neuronal degeneration and cancer,etc.Therefore,it is of great significance to identify and detect hypochlorous acid in organism.In recent years,small molecule fluorescent probes have been widely used in various detection fields due to their excellent selectivity,high sensitivity,and rapid response.Among them,the near-infrared fluorescent probe has the advantages of strong tissue penetration and low light damage to the cells,causing widespread concern and research.In this paper,we designed and synthesized two kinds of near-infrared fluorescent probes for detecting hypochlorous acid,which provide a powerful tool for the identification and detection of hypochlorous acid in vitro and in vivo.The work of this thesis mainly includes two aspects:1.We designed and synthesized a near-infrared fluorescent probe for detection of hypochlorous acid using cresyl violet as a fluorescent precursor,and successfully applied it to the visualization of intracellular hypochlorous acid.The design of the probe is mainly based on the photoinduced electron transfer(PET)principle,and hypochlorous acid is detected with thioether as a recognition site.Before the interaction with hypochlorous acid,the probe has only weak fluorescence.After the action with hypochlorous acid,the sulfide was oxidized to sulfoxide,the PET effect disappeared,and the fluorescence was significantly enhanced.Under simulated physiological conditions,the probe showed a good linear relationship with the concentration gradient of hypochlorous acid: the linear correlation coefficient was 0.9965,and the detection limit was 94.7 nM.At the same time,other substances in organism do not interfere with the probe’s response to hypochlorous acid.In addition,visualization fluorescent imaging of hypochlorous acid in cells and in vivo was successfully achieved.2.Using Aza-BODIPY as a fluorescent precursor,we designed and synthesized another kind of "double lock" near-infrared fluorescent probe for detecting hypochlorous acid.We first synthesize a fluorescent precursor using the traditional method of synthesis of Aza-BODIPY,and then the dye is modified to introduce a thiomethyl group and a oximido group on the fluorescent precursor.In this way,the probe has both thioether and oximido as reactive sites for the precise recognition of hypochlorous acid.This "double-locked" probe can greatly improve the selectivity of the probe for accurate detection of hypochlorous acid.At the same time,the near-infrared fluorescent probe can effectively avoid the interference of the organism’s autofluorescence,providing a potential tool for the accurate detection of hypochlorous acid in cells and in vivo.