Design And Synthesis Of New Ratiometric Fluorescent Probes And Supramolecular (CB[n])-based Vector For Sensing And Drug Delivery In Biological Redox Microevironment

Based on the fact that two-isophorone fluorophore and pyridinium derivatives serve as the fluorophore,and using the 2,4-dinitrobenzenesulfonyl?DNBS?and aryl boronate as recognition groups,respectively.New ratiometric fluorescent probes were designed for the detection,analysis,and dynamic biological imaging of biothiols and hydrogen peroxide.In addition,exploring the application of supramolecular latch-up system in drug delivery,and combining with fluorescence analysis technology.?1?2,4-Dinitrobenzenesulfonyl?DNBS?has been widely used for the design of small fluorescent probes for biothiols due to its high reactivity.However,most DNBS-based fluorescent probes exhibit‘‘off–on''fluorescence response towards biothiols due to the strong quenching effects of DBNS on the fluorophores.Herein,we present an alternative design of a ratiometric fluorescent probe based on DNBS for biothiols.A new fluorophore bearing two isophorone malononitrile structures was conjugated with DNBS to provide a target probe?CHT?,which exhibited a ratiometric sensing behavior towards biothiols.The sensing process is rapid and highly selective.Most importantly,CHT has high stability in the quantitative detection of Cys compared to the control probe CHM,which performed an‘‘off–on''sensing for biothiols.Endogenous biothiols were successfully monitored with CHT in live cells through the ratiometric fluorescence signal.This new fluorophore bearing two isophorone malononitrile moieties will pave a new avenue to design ratiometric fluorescent probes for imaging and quantitative detection.?2?With this research we presented a ratiometric and mitochondria-target fluorescent probe?Mito-HT?for detection of H₂O₂ both in vitro and in live cells.Mito-HT was constructed by direct conjugation of aryl boronate to fluorophore with three synthetic steps.The borate group is cleaved from Mito-HT in the presence of H₂O₂,resulting in the exposure of the hydroxyl group of the electron donating group.Then the ICT mechanism was turned on,and the fluorescence emission of Mito-HT at 493 nm was red-shifted to 562 nm,thereby achieving radiometric detection of H₂O₂.Mito-HT exhibited a highly selectivity towards H₂O₂,and this interaction can be completed within 40 min.Mito-HT could be used for quantitative detection of H₂O₂?0-200?M?through ratiometric fluorescence signal readout.And limit of detection?LOD?is approximately 0.33?M.The relatively high stability and medium fluorescence quantum yield of Mito-HT?0.39?and Mito-HT-OH?0.43?enable clear mitochondria localization and dual-channel fluorescence imaging of H₂O₂ in live cells with confocal microscopy.?3?At present,the carriers for drug release are single,mostly are the nanoparticles.However,the release systems based on Cucurbit?CB[n]?are mostly light-controlled,which is difficult to control,and don't conduct the biological experiment.Therefore,we hope to combine guest molecules that are easy to bind to CB[n],such as amantadine,1,4-bis?aminomethyl?benzene,etc.,with small molecule receptors,so that achieve the purpose of inducing drug release by active molecules in cells,and through small molecule fluorescent dye to visualization.