Design And Synthesis Of Novel Fluorescent Probes For Detection Of ClO~- In Vivo And Its Applications

There are a large number of small molecules in organisms including monosaccharide,reactive sulfur species（RSS）,reactive nitrogen species（RNS）and reactive oxygen species（ROS）,etc.They play an extremely important role in whole life process,such as anti-tumor,anti-inflammation,anti-aging and so on.Among them,ClO^-is a kind of vitally important ROS,which could produce effective antibacterial effects when microorganisms invade organisms.However,excessive accumulation of ClO^-could lead to tissue damage and cause a variety of diseases.Therefore,rapid and in situ detection of ClO^-in vivo is a current research hotspot.Nowaday,the fluorescent probe is a reliable method for detection of ClO^-.In recent years,the ratiometric fluorescent probes have been developed rapidly due to many advantages.The ratiometric fluorescent probe is a signal to detect analytes using the ratio of different wavelengths of fluorescence intensity,which could overcome some defects of the previous single-wavelength probes,such as the date they acquired is the fluorescence intensity of a single wavelength that is influenced easily by external environment,the sample concentration,and the instrument conditions and so on.At the same time,they could also improve the selectivity,sensitivity and dynamic response range of the detected substance.In this thesis,three small molecular fluorescent probes were designed and synthesized based on different reaction mechanisms for the detection of ClO^-,the thesis includes four chapters,and its main contents are as follows:In chapter 1.The chapter introducts four different reaction mechanism for the ratiometric fluorescent probes inculding Intramolecular Charge Transfer（ICT）,Excited States Intramolecular Proton Transfer（ESIPT）,Fluorescence Resonance Energy Transfer（FRET）,and Through-Bond Energy Transfer（TBET）.Additionally,the research status and significance of the ratiometric fluorescent probes are summarized.Finally,the main research ideas of this paper are put forward based on this.In chapter 2.Based on the coumarin skeleton,fluorescent probe MTPP was synthesized using methyl pyridine iodized salt as a recognition group.Probe MTPP itself had no fluorescence.When ClO^-was added to the system,the C=C bond was cut off and the aldehyde group was exposed in the probe scaffold.Since the aldehyde group had a strong pulling electron effect,a push-pull electron system was formed in the molecule,which resulted in strong fluorescence characteristics.The detection of ClO^-in organisms was achieved by the fluorescence"Off-On"principle.The linear range of ClO^-concentration detection of probe MTPP is 0-20μM with the detection limit of 7.8 nM,and this probe could be used for fluorescence imaging analysis of ClO^-in SH-SY5Y cells successfully.In chapter 3.A new fluorescent probe HMAT was designed and synthesized with coumarin as the basic framework and p-methoxyphenol as the recognition group.There was a PET effect between coumarin fluorescence group and receptor unit,which had a strong quenching effect on fluorescence.But when ClO^-was added to the system,p-methoxyphenol was oxidized to benzoquinone,the PET effect was inhibited,and the fluorescence group emited strong fluorescence.Probe HMAT itself had weak fluorescence signal at 500 nm,the fluorescence signal of the reaction system was significantly enhanced when ClO^-was added and the fluorescence intensity at 500 nm had a good linear relationship with the concentration of ClO^-in the range of 1-9μM,with a detection limit of 1.3 nM.This probe could be used for fluorescence imaging analysis of ClO^-in SH-SY5Y cells successfully.In chapter 4.A ratiometric fluorescent probe DDD was designed and synthesized for the detection of ClO^-using 6-methoxy-1-tetralone as starting material.The probe itself exhibited very weak dual fluorescence emission characteristics with emission peaks at 555 and 635 nm,respectively.When ClO^-was added,the fluorescence signal of the probe at 635 nm was weaked,while that at 555 nm was enhanced.The results of fluorescence titration showed that the fluorescence ratio I_{555 nm}/I_{635 nm}35 nm of the reaction system presented a good linear relationship with the concentration of ClO^-in the range of 4-20μM,with a detection limit of 78 nM,and the ratio imaging effect was well achieved in SH-SY5Y cells and zebrafishs.