Studies On Design,Synthesis And Applications Of Xanthene And Cyanine Skeletons-based Multifunctional Fluorescent Probes

In recent years,fluorescent probes are widely used to detect the biological and environmental analytes.Especially the long wavelength fluorescent probes have shown more extensive and attractive application prospect on account of low scattering of excitation and emission light,low background,and less cells and living organisms photodamage.Besides,multi-analytes sensing fluorescent probes have drawn a vast amount of research interest due to the low-cost and high-efficiency compared with fluorescent probes with single-analyte sensing.The work of this dissertation focused on design and synthesis of long wavelength fluorescent probes(xanthene and NIR-cyanine skeletons-based)for quantitative determination of VO²⁺/Cu²⁺/PPi,F^-/N₂H₄,reactive mercapto species(thiophenol and Cys/Hcy/GSH).(1)26 kinds of fluorescent receptors,including 12 xanthene skeleton-based fluorescent probes,were systematically designed,synthesized,and studied for their VO²⁺sensing performance.The representative probe RhDBS features the fluorescence"off-on-off"switch,which can realize the reversibility detection of VO²⁺/Cu²⁺/PPi.The probe is highly responsive to VO²⁺,and the detection limit is 3.65 n M,and VO²⁺can also be detected by naked eye.Additionally,the probe can be exploited for electrochemical sensing of VO²⁺ions.RhDBS can rapidly detect VO²⁺/Cu²⁺/PPi in-field,and trace intracellular VO²⁺in living cells.It is the first reported long wavelength fluorescent probe capable of detecting VO²⁺in vitro.More importantly,some laws between the structure and sensing performance of rhodamine-based VO²⁺fluorescent probes have been found,which is beneficial to designing fluorescent probes toward VO²⁺with good performance.(2)Two kinds of F^-/N₂H₄ bifunctional fluorescent probes named FNBS and Cy-NBS with 4-nitrobenzene sulfonyl group were well designed and synthesized.FNBS,as a green light emission probe,can realize the naked eye identification for F^-/N₂H₄ as well as the rapid detection of F^-/N₂H₄in-field,while Cy-NBS is a near infrared F^-/N₂H₄fluorescent probe based on xanthene-cyanine skeleton,which can rapidly(<3 min)detect F^-/N₂H₄with high sensitivity,and the detection limits for F^-and N₂H₄ have been determined to be 57.51 n M and 38.02 n M,respectively.To our knowledge,this is the first near-infrared fluorescent probe capable of simultaneously detecting F^-and N₂H₄.Both probes were used for imaging detections of F^-and N₂H₄in living cells due to their low cytotoxicity.(3)Two thiophenol/biothiol near-infrared fluorescent probes Cy-DNBS and Cy-RSH containing2,4-dinitrobenzene sulfonyl and acrylyl as recognizing moieties were separately designed and synthesized.Cy-DNBS can detect thiophenol and Cys/Hcy under different test conditions,respectively.Cy-DNBS shows an especially excellent sensitivity to thiophenol,and the detection limit is 34.15 n M.It has been employed to trace exogenous thiophenols in zebrafish due to its near-infrared emission(804 nm)and biological compatibility.In addition,Cy-RSH can detect Cys/Hcy/GSH simultaneously under the CTAB micellar system with low detection limits down to nanomolar level.The probe Cy-RSH is used for the imaging detections of endogenous and exogenous biothiols in living cells because of the good light stability and low cytotoxicity.(4)Three near infrared cyanine-based fluorescent probes with large Stokes shifts(78-90 nm),namely Cy-M,Cy-SM,and Cy-SDM which containing thiophenol groups were elaborately designed and synthesized,and the differences of steric hindrance and nucleophilic between Cys,Hcy and GSH were used to realize simultaneous identification and detection of Cys and Hcy.Amongst them,Cy-SM has the best Cys/Hcy sensing performance,and the detection limits are found to be 15.5 n M and49.4 n M,respectively.In view of its low cytotoxicity and outstanding sensitivity,Cy-SM can be resoundingly employed for the quantitative detection of biothiols in reduced bovine serum as well as imaging detection of endogenous and exogenous Cys/Hcy in living cells.