Design,Synthesis And Biological Application Of Organic Fluorescent Probes For Detection Of Biothiol And Viscosity

Fluorescent probe technology is a technology that utilizes the photophysical or photochemical characteristics of the probe to analyze and detect the analyte.Bioimaging is an important application field of fluorescent probes,which is of great significance for clinical diagnosis and pathological analysis.Materials for fluorescent probes include carbon dots,quantum dots and organic small-molecule.Among them,organic small-molecule fluorescent probes have the advantages of low cost,simple operation,high sensitivity,non-invasiveness,fast response,good biocompatibility,and real-time analysis.Traditional organic small-molecule fluorescent probes usually use a single detection principle to identify a single target,which limits its application range and affects its further development.Therefore,the design and development of fluorescent probes with multi-mechanism complex and multi-parameter-induced fluorescence signal changes is the future development direction of this field.In the work of this thesis,we developed four fluorescent probes with biothiol and viscosity as analytes.The main research contents are as follows:(1)Based on Intramolecular Charge Transfer(ICT)and Excited-State Intramolecular Proton Transfer(ESIPT)mechanisms,a novel near-infrared fluorescent probe BMQ-A for Cys detection was developed.The probe has large Stokes shift(310nm),near-infrared light emission(740 nm),good water solubility,short response time(15 min),wide p H response range(5.5-8.0),good selectivity and high sensitivity(LOD0.062 ?M)and other advantages.The mechanism of fluorescence emission of the probe was explained by theoretical calculation simulation.In addition,we also explored the cytotoxicity of BMQ-A,and finally applied it to the fluorescence imaging of endogenous and exogenous Cys in A549 cells and the quantitative determination of Cys in human serum samples.(2)A novel near-infrared fluorescent probe DBF-A for Cys detection was developed based on Photo-induced Electron Transfer(PET)and Twisted Intramolecular Charge Transfer(TICT)mechanisms.The probe not only has the advantages of good selectivity,long emission wavelength(600-800 nm),large Stokes shift(159 nm),and low detection limit(0.056 ?M),but also exhibits good bioimaging capabilities and has been successfully using for fluorescence imaging of endogenous Cys in Hep G2 cells.Furthermore,we found that the product of the reaction DBF-A with Cys,DBF-OH,to be highly sensitive to viscosity.The PET process of DBF-A and the TICT process of DBF-OH was verified by theoretical calculations,and the mechanism of fluorescence quenching of DBF-A and the fluorescence changing of DBF-OH with viscosity were well explained.(3)A fluorescent probe BEB-A for Cys and viscosity detection was developed based on PET,ESIPT and TICT mechanisms,and simultaneously realized the detection of Cys in living cells and the imaging of nucleoli in the nucleus.BEB-A has the following features:(i)It has excellent response speed,Cys detection can be completed within 10 min in vitro,and intracellular Cys detection can be completed within 3 min,which is faster than most of the previously reported fluorescent probes;(ii)It has high response sensitivity with an LOD as low as 0.027 ?M and a long emission wavelength(613 nm);(iii)It is highly selective and does not interfere with the structurally similar interferers GSH and Hcy;(iv)BEB-OH,the product of the in situ reaction between BEB-A and Cys in living cells,is sensitive to viscosity and can bind to RNA to achieve fluorescent staining of nucleoli.(4)A novel fluorescent probe TPQ-G for biothiol and viscosity detection was developed based on PET and TICT mechanisms.The probe has good water solubility and bioapplicability,and has good selectivity for biological thiols.Secondly,the system after the reaction of probe and GSH has a good response ability to viscosity,therefore,the probe can realize quantitative analysis of GSH and viscosity at the same time.Based on the high GSH concentration and high viscosity of cancer cells,TPQ-G has been successfully used to distinguish cancer cells from normal cells.In addition,TPQ-G has also been successfully applied to tumor imaging in tumor-bearing mice.