Organic Small Molecule Fluorescent Probes For The Detection And Imaging Of Several Disease-related Factors

Factors that cause disease are often closely related to the content of various substances and the steady state of microenvironment in cells.The study of disease-related factors in organisms,such as small molecular,biological enzymes and intracellular microenvironment,can assess the progress of disease by the level of molecular,and provide more basis for studying the initiation and progression of diseases.Based on their advantages of structure controllability,sensitive response,high selectivity,and visual analysis,small molecular fluorescent probes show potential application in the fields of environmental analysis,biomarkers,cell and tissue imaging,clinical diagnosis and treatment.However,due to the complex of biological systems,especially,the existence of self-absorption and spontaneous fluorescence will cause certain interference to detection.Thus,development of small molecule fluorescent probes with faster response,better selectivity and high photostability for biological samples analysis is still the hotspot and challenge of current research.The long-wavelength emission fluorescent probes can effectively avoid the interference of spontaneous fluorescence in biological system,improve the imaging penetration depth,and decrease the damage of tissue caused by short excitation wavelength.Besides,fluorescent probe with a large Stokes shift can reduce the self-quenching of fluorescence and false negative signals,make the detection result more accurate.In addition,probes with good photostability have superior resistance to photobleaching and are more suitable for real-time monitoring.Therefore,fluorescent probes with long wavelength emission,good photostability,and large Stokes displacement show great advantages and broad application prospects in visual imaging analysis of biological system.In this paper,to achieve high sensitivity and selectivity response of several disease-related factors in vivo,five fluorescent probes with good optical properties and detection performance for imaging hydrogen sulfide?H₂S?,alkaline phosphatase?ALP?,ClbP enzyme and viscosity in living cells were designed and synthesized,and the application value of these probes in disease diagnosis was verified.The main research contents are as follows:?1?An effective fluorescent probe?E?-1,3,3-trimethyl-2-?4-morpholinostyryl?-3H-indole-1-iodide?Mi?for rapidly detecting H₂S based on intramolecular charge transfer?ICT?mechanism was reasonable designed and synthesized from 1,2,3,3-tetramethyl-3H-indolium iodide and 4-?4-morpholine?benzaldehyde.Mi showed obvious red fluorescence before reacting with H₂S.However,when H₂S existed,the addition reaction occurred,and the?electron conjugation system of Mi was destruction,which caused the quenching of the fluorescence of Mi.The probe exhibited high selectivity and sensitivity to H₂S and could be used for rapid detection of H₂S within 2 minutes.In addition,after incubating with H₂S,a remarkable color change of Mi from red to colorless was noticed,which means Mi can be used for colorimetric detecting H₂S.More importantly,due to the superior performance of Mi,it was successfully applied to detect H₂S in HeLa cells,proving the potential application of Mi in the field of biology.?2?An aggregation-induced emission?AIE?fluorescent probe,?E?-2-???9H-fluoren-9-ylidene?hydrazono?methyl?phenyl dihydrogen phosphate?FAS-P?was designed and synthesized,that can respond to ALP with a remarkable large Storks shift?>200 nm?based on excited state intramolecular proton transfer?ESIPT?mechanism.The probe consisted of recognition unit of phosphate group and fluorophore of?E?-2-???9H-fluoren-9-ylidene?hydrazono?methyl?phenol?FAS?.FAS was chosen as fluorophore because of its good water solubility,excellent cell permeability,properties of LDs localization and efficacious fluorescence quenching through the substitution of hydroxyl group.Reaction of FAS-P with ALP resulted in the recovery of FAS fluorescence due to the hydrolysis of the phosphate ester group.FAS-P has high selectivity and sensitivity to the detection of ALP.Agood linear relationship was obtained between the fluorescence intensity of FAS-P and ALP activity in the range of 1-100U/L,the limit of detection?LOD?is as low as 0.6 U/L.More importantly,we successfully applied FAS-P to detect ALP in living cells and the monitoring of ALP in real time.?3?A near-infrared fluorescent probe?S,E?-N1-?4-?2-?3-?double Cyanomethylene?-5,5-dimethylcyclohex-1-en-1-yl?vinyl?phenyl?-2-tetradecanoamidosuccinamide?DCMA-T?was designed and synthesized for detecting ClbP enzyme.N-myristoyl D-asparagine was chosen as recognition group for specific sensing ClbP.DCMA-T has no fluorescence,after the hydrolysis of ClbP,N-myristoyl D-asparagine left and a strong red fluorescence at 660 nm occurred.DCMA-T showed high selectivity and good biocompatibility to ClbP,and was successfully applied to imaging of ClbP in E.coli.?4?A red-emitting fluorescence probe?E?-2-?3-?4-?dimethylamino?phenyl?-1-?4-hydroxyphenyl?arylene?malononitrile?DDP?with?,?-unsaturated double bonds for sensing viscosity was designed and synthesized form 4-hydroxyacetophenone,malononitrile and 4-?dimethylamino?benzaldehyde.DDP showed high selectivity and high sensitivity for the detection of viscosity.In a low viscous environment,the C-C single bond in DDP can rotate freely,showing weak fluorescence.In a viscous environment,intramolecular rotation is suppressed,and the fluorescence of DDP is significantly enhanced.In addition,based on excellent photostability,good biocompatibility and other advantages,DDP was successfully used for the differentiation detection of glioma cells and glioma cells.?5?A mitochondria-targeted red-emitting fluorescent probe?E?-(4-?4-?4-?1,1-dicyano-4-?4-?dimethylamino?phenyl?butane-1,3-dien-2-yl?pheno xy?butyl?triphenylphosphorus?Mito-DDP?with good photo stability and blood-brain barrier permeability was reasonable designed and synthesized for viscosity detecting and imaging.The cyano group was introduced into Mito-DDP for the improvement of photostability.Besides,the molecule that possesses?,?-unsaturated double bonds and conjugate structure of?electron in Mito-DDP was selected as the fluorophore for sensing viscosity with high selectivity and sensitivity.Triphenylphosphine was reasonably introduced as mitochondrial targeting group to endow Mito-DDP with Mito-targeting character.In a low-viscosity environment,the C-C single bond in Mito-DDP can rotate freely with restriction,resulting in a decrease of the fluorescence intensity.While in high-viscosity environment,the intramolecular rotation is inhibited,the fluorescence intensity of Mito-DDP is significantly enhanced.In addition,based on the advantages of superior photostability,good biocompatibility and function of mitochondrial targeting,Mito-DDP has been successfully applied to imaging the change of viscosity in cells and Drosophila brain.