The Construction Of Novel Small-molecule Organic Fluorescent Dyes And Their Bioligical Applications

Fluorescent dye is an important branch of dyestuff chemistry.In recent decades,fluorescent dyes have achieved many breakthroughs in the application of materials,biology,medicine,and solar energy.Herein,fluorescent dyes have gradually become the key basic research direction in dyestuff chemistry.Despite organic fluorescent dyes possess complex and diversiform structures,they,in fact,usually contain fluorescent core skeleton with a large conjugate system and auxochrome group enabling to alter wavelengths and enhance fluorescence(such as amino,amide,etc).Recently,with the rapid development of biology,life science,medicine and other disciplines,organic fluorescent dyes have been widely applied in biomolecules labeling,enzyme analysis,environmental analysis,cell staining and clinical diagnosi.Therefore,the exploration and development of various high-performance functional organic fluorescent dyes is urgently demanded.For the most reported organic fluorescent dyes,their photophysical and photochemical properties are not particularly perfect in all respects and can not meet the growing development of chemical biology.Therefore,in this thesis,we mainly focus on the enhancement and improvement of the photophysical and photochemical properties of fluorescent dyes.For this purpose,a series of novel fluorescent dyes have been designed and constructed based on the hybridization strategy.Furthermore,these new dyes have also been successfully applied in the development of fluorenscent probes for bioimaging.The detailed works are as follows:(1)To enhance the chemical stability of traditional near-infrared dyes,a new type of near-infrared dye with strong chemical stability,XC,was designed and synthesized by using the hybridization strategy.The chemical stability of XC was superior to the reported HD dyes and commercial indocyanine green(ICG),especially in the case of H2S enviorment.We have systematically studied the synthesis conditions of XC dyes and found that the anhydrous conditions were more favorable for the successful synthesis of the target dyes.We further explored the synthesis mechanism of the dyes through comparing the control experiments.The study of the spectral properties indicated that the absorption and emission spectra of XC dyes were both appeared in the near-infrared region.In order to confirm the superior stability of the XC dyes,we subsequently detected the stability of the XC dyes towards various oxidants,reductants and strong nucleophiles.As a result,the dyes do show the strong chemical stability as we expected.Finally,corresponding theoretical calculations also further demonstrated the special spectral properties and superior chemical stability of the XC dyes.(2)We designed and synthesized a near-infrared turn-on H2S fluorescent probe XC-H2S with superior chemical stability based on the developed XC dyes.Spectroscopic studies showed that the probe XC-H2S enable a rapid response,high sensitivity,good selectivity,and even a 35-fold fluorescence enhancement towards H2S.Interestingly,cell experiments showed that the probe could detect exogenous H2S and endogenous H2S produced by the enzyme-catalyzed of thiols.Finally,the probe was successfully applied to in vivo imaging of Kunming mice.(3)A novel type of near-infrared fluorescent dyes CHMC have been designed and synthesized based on hybridization strategy.The CHMC dyes bear excellent photochemical properties including the emission in the NIR region,large absorption extinction coefficients,and good fluorescence quantum yields.Most importantly,the CHMC dyes own two interaction sites(hydroxyl and chlorine atom),which effectively supply more functional strategies contrast to the previously developed near-infrared dyes with one interaction site.With the aim to verify the availability of two interaction sites,we applied the CHMC dyes to design the fluorescent probes.Firstly,the hydroxyl site was used for pH detection.As the pH values increased from 3.0 to 10.0,the ratio fluorescence intensity of CHMC dyes increased from 0.43 to 52.3.Secondly,another interaction site,the chlorine atom,was used as the recognition site for thiol detection.When using CHMC dyes for thiol detection,the ratio of fluorescence intensity of the dyes increased from 0.26 to 7.7.(4)A new type of full-color-tunable two-photon fluorescent dye,TPFC,was designed and synthesized based on the hybridization strategy,which was a hybrid of naphthalimide dye and indole unit.According to the design requirements,the common dye core skeleton should have good one-photon and two-photon fluorescence performance,large Stokes shifts and facilely functionalized structure.In order to verify our design,we first studied their spectral properties in detail and found that the TPFC dyes were as good as our designs.Furthermore,it was worth noting that the one-photon and two-photon fluorescent emission wavelengths of these dyes can be easily adjusted from the blue wavelength region to the near-infrared region,which enriched the emission interval of the two-photon fluorescent dyes.In view of these excellent one-and two-photon properties,we used TPFC-Lyso-4 as the representative example,and applied it to design the two-photon ratiometric lysosomal targeting thiols probes.In addition,the new ratiometric probe TPFC-Lyso-Cys could be used not only for the thiols detection in lysosomes,but also for thiols detection in fresh liver tissues.