Design, Synthesis And Analytical Application Of Hypochlorous Acid And Hydrogen Sulfide Molecular Fluorescent Probes

Reactive oxygen species(ROS)including hypochlorous acid(HOCl),superoxide anion radicals(O2·-),hydrogen peroxide(H2O2),singlet oxygen(1O2),peroxynitrite(ONOO),and hydroxyl radicals(·OH),are commonly produced by organisms in the process of life activities.Endogenous ROS is mainly produced during mitochondrial respiration.Exogenous ROS comes from ultraviolet radiation,intake of exogenous substances and pathogenic factors.Many studies have demonstrated that ROS play a variety of roles in biological processes,such as signal transduction,inflammatory response,carcinogenesis and neurodegenerative damage.Although many normal physiological activities require the participation of ROS?when ROS is overexpressed,it will cause the oxidation of liposomes,proteins and DNA,and then lead to oxidative stress,resulting in the disorder of related organism functions.Hypochloric acid(HOCl)is a highly oxidizing species produced by the reaction of hydrogen peroxide with chloride ions catalyzed by myeloperoxidase(MPO)in activated phagocytes.When pathogens invade,HCIO can kill the invading microorganisms and play an important role in the innate immunity of the host.However,uncontrolled HClO concentration in vivo can lead to tissue and organ damage,which is closely related to inflammatory diseases,neurodegenerative diseases,cancers and so on.Sulfydryl-containing small molecules,such as hydrogen sulfide(H2S),glutathione(GSH),cysteine(Cys)and homocysteine(Hcy),play an important role in cells as essential active molecules.They are antioxidants during oxidative stress reaction,and can chelate with metal ions.These small active molecules can maintain cell homeostasis and metabolic balance in normal concentration.However,excessive or low concentration of these molecules will lead to the imbalance of redox process,resulting in the malfunction of cells.Cancer,cardiovascular disease,Parkinson's syndrome,Alzheimer's disease and many other major diseases are closely related to the metabolic disorders of biothiols.In this paper,two small molecule fluorescent probes were designed and synthesized to detect HClO and H2S,respectively.Their applications in bioimaging were displayed.The details are as follows:(1)In this section,a two-photon fluorescence probe for ratiometric imaging of hypochlorite has been developed by using the oxidation-elimination cascade reaction of a-phenylselenone.The probe is highly sensitive,selective,fast,and responsive to HClO with two-photon excitation and near-infrared emission.It can detect the production of HClO in cells and inflammation animal models.(2)In this section,based on the principle of PET and ESIPT,a novel two-photon fluorescent probe was developed by binding 2,4-dinitrophenyl ether to flavonoid dyes for H2S detection in endoplasmic reticulum.This probe was synthesized simply and can be used to detect H2S in live cells.