Synthesis And Application Of Near-infrared Fluorescent Probes Based On Merocyanine Dyes

Hydrogen Peroxide（H₂O₂）and hydrogen sulfide（H₂S）are important messenger molecules in cells,their abnormal contents often accompany with the occurrence and development of diseases.In recent years,because of the specificity,high efficiency and sensitivity of fluorescence detection technology,the detection of small molecules in living system by fluorescence detection technology has become a research hotspot.Among them,the near-infrared fluorescent probe has greatly advanced the imaging research of cells,tissues and living bodies due to their long wavelength emission advantages.Cyanine dyes,as an important part of near-infrared fluorescent dyes,have attracted much attention in synthesis and biological applications due to their excellent properties such as easy synthesis,high fluorescence quantum yield and easy construction of modifiable ICT reaction site.In this paper,Four long wavelength fluorescent probes were designed and synthesized,which were fluorescence probe TC-BOR and TC-BOH for hydrogen peroxide,TC-DNP and TC-DS for hydrogen sulfide,respectively,use near-infrared fluorescent dye-benzoindoline semicarbaine as the fluorophore.Then,the probe TC-BOR and probe TC-DS with better performance were tested and studied completely.In the second chapter,the fluorescent probes TC-BOR and TC-BOH were designed and synthesized,which is used borate ester as the recognition group.The comparison of in vitro detection shows that the performance of probe TC-BOR is better.Under the excitation of 690nm light,the probe TC-BOR fluoresces at 723 nm,with 55-fold NIR fluorescence enhancement,a rapid response within 7 min;at the same time,TC-BOR shows high selectivity to H₂O₂ and low cytotoxicity to He La cells,Imaging of He La cells shows that fluorescence intensity change significantly before and after the addition of exogenous hydrogen peroxide,which is suitable for the detection of exogenous H₂O₂ in living system.In addition,the probe was successfully used to detect H₂O₂ in food,which expanded the application range of fluorescence detection technology.In the third chapter,two cases of hydrogen peroxide fluorescent probe TC-DNP and TC-DS were designed and synthesized which is used DNP and 2-（2-Dithiopyridine）salicylic acid as the recognition group.Through experimental comparison,the performance of TC-DS was better,and then it was completely tested in the test system of DMSO-PBS.The results showed that the probe has a very low detection limit,as low as 42 n M,which can realize the quantitative detection of low concentration of H₂S.The reaction time is less than 7 min,which greatly reduces the detection time of H₂S.Meanwhile,the probe has strong fluorescence emission at 723 nm after being excited by 690 nm near infrared light;Then,the probe shows excellent specificity and selectivity for H₂S,which can be distinguished from other biological mercaptan,and is suitable for detection of H₂S molecules in vivo and in vitro.