Design,Synthesis And Application Of Fluorescent Probe For Hypochlorous Acid

Hypochlorous acid,as one of the important small molecules of active oxygen in living organisms,plays an important role in the biological immune system.The research shows that when the concentration of hypochlorous acid in the body is too high,it can cause different degree of damage to the biological tissue,thus causing the body disease.Therefore,it is very important to detect the concentration of hypochlorite acid accurately in order to reveal the physiological and pathological process of hypochlorite acid.Recently,fluorescent probes as an ideal tool are extensively used for monitoring biologically important molecules,because of their unique superiorities including high sensitivity,operational simplicity,and bioimaging analysis in vivo,even in single living cells compared with other detecting methods.On the basis of summarizing the literatures on hypochlorous acid in recent years,three fluorescent probes were designed and synthesized for efficient detection of hypochlorous acid,and their fluorescence properties and biological applications were also discussed.The main contents of the dissertation are presented as follows:(1)A turn-on two-photon fluorescent probe HCA-Green for hypochlorous acid(HOCl)was synthesized by using 4-methylamino-1,8-naphthalimide(MNA)as the two-photon fluorophore and p-hydroxyaniline as the leaving–recognition domain.The probe enables the rapid and highly selective and sensitive monitoring of HOCl in living cells.The fluorescence emission intensity of the probe was enhanced by ~229 and ~193 respectively under the excitation of single-photon and two-photon light sources,indicating the high sensitivity of the probe to HOCl.The detection limit of this probe for HOCl in PBS buffer is 42.28 nM.At the same time,the probe is highly selective for HOCl over the interfering species which indicates that it can be used in complex cell environments.(2)A novel specific fluorescent probe,YG-Red,was designed and synthesized based on rhodamine spironyl turn-on loop and used seminaphthorhodafluor as the fluorophore.The experimental results showed that the fluorescence intensity of the probe increases linearly within a certain concentration range of HOCl,and it can specifically recognize hypochlorite.The probe has high sensitivity,low detection limit and rapid response(about 50 s).The two-photon experiment shows that the probe has a large two-photon action cross-section(122 GM)and can exist stably in the physiological pH.It is a good two-photon fluorescence probe and is expected to be successfully applied to the detection of bioactive substances in vivo.(3)A novel mitochondrial-targeted two-photon fluorescent probe ES-HOCl,was constructed based on rhodamine-like structure and its optical properties were investigated.The experimental results showed that the probe is sensitive to hypochlorite acid and has good selectivity.At the same time,the probe can exist stably in the pH range of 4 ~ 8.(4)Based on the synthesis and sensing properties of these new probes,we also try to apply the probe to the bioimaging.It indicated that probe ES-HOCl can monitor exogenous and endogenous hypochlorite and localize mitochondrial cells,which provides strong evidence for further research.