The Design,Synthesis And Properties Of ESIPT/AIE Mechanism Fluorescent Probe

Fluorescent probe has advantages of high sensitivity,simple operation,high selectivity and visualization.It has broad application prospects in environmental detection,cell imaging,clinical diagnosis and treatment.Esterase is a kind of hydrolase that hydrolyze lipids.It participates in a wide range of physiological activities for human body.At the same time,esterase is common target in prodrug design.However,many diseases such as wolmann disease,hyperlipidemia and cancer are related to abnormality of esterase.Therefore,we can develop fluorescent probes to detect esterase whether esterase is abnormal in biological samples.β-galactosidase（β-gal）is a kind of hydrolase that hydrolyze substances containing galactoside bonds.Research shows,the occurrence of ovarian cancer is related to the abnormality ofβ-gal.Therefore,tastingβ-gal content has positive significance for the early diagnosis of ovarian cancer.Hydrazine（N₂H₄）is an important chemical material,which is used to prepare various industrial products and intermediates.However,N₂H₄ is substance with biological toxicity.It can enter the human body through breathing,skin contact and other ways,damage the liver and central nervous system,and may lead to cancer and gene mutation.Therefore,it is necessary to develop a fluorescent probe that can detect N₂H₄ in vitro and biological samples.Based on the above problems,the main work of this paper is as follows:（1）Herein,a novel fluorescent probe Y-1 for monitoring esterase in biological samples was rationally designed.The probe Y-1 uses naphthalimide-benzothiazole coupling as the fluorophore.The benzothiazole group not only makes the fluorophore having ESIPT mechanism,but also enlarges the p-πconjugation in the probe.It makes the probe possess excellent spectral characteristics,large molar absorption coefficient and high fluorescence quantum yield.In spectral test,the detection limit of probe Y-1.Probe Y-1 high selectivity and photostability towards esterase.The probe had high affinity for esterase and catalytic efficiency by enzymatic kinetic test.For biological applications,our probe is visualizing esterase in living Hep G2 and Co Lo205 cells.It proved that orlistat to effectively inhibit the activity of cellular esterase.Furthermore,it has been successful in monitoring the esterase in zebrafish,the data were consistent with cellular phenomena.（2）In order to quantitatively detectβ-gal,we design a system based on ESIPT/AIE double mechanism ratio fluorescent probe Y-2.The probe uses 2’-hydroxychalcone derivative（HCA）as the fluorophore.The ESIPT process is activated by the structural tautomerism of enols,resulting in a large emission red shift of fluorophores.HCA has good AIE properties.In buffer,HCA appeared obvious aggregation with the increase of water content elephant.In the fluorescence spectrum test,probe Y-2 andβ-gal after reaction were observed that the large Stokes shift and large emission red shift.Probe Y-2 has a low detection limit,good selectivity and high sensitivity.The probe was obtained by enzymatic kinetic test,indicating that the probe Y-2 has high affinity and catalytic efficiency.Finally,imaging result table The probe can quantitatively detect the cellularβ-gal.（3）Fluorescent probe Co-NH was designed and synthesized for the detection of hydrazine hydrate（N₂H₄）based on AIE mechanism.Probe Co-NH was usedα-cyanostilbene styrene derivative as fluorescence skeleton and coumarin was introduced to increase fluorescence quantum yield.With the increase of water content in buffer,the probe Co-NH appeared obvious aggregation,and showed large Stokes shift and obvious red shift.The results of spectral detection showed that probe Co-NH has a low detection limit,high selectivity and photostability.Next,probe Co-NH was successfully detected N₂H₄ on the thin-layer chromatographic,it proved that the probe Co-NH can detect N₂H₄ in the environment in solid state.Finally,imaging experiment,the probe was successfully detected N₂H₄ in living cells and zebrafish,indicating that probe Co-NH has the ability to detect N₂H₄ in biological samples.