Design,synthesis,and Application Of Fluorescent Probes Based On Long Wavelength Detection Of Bioactive Sulfur/Active Oxygen

Biologically active small molecules play an important role in maintaining the redox state of biological systems,and they are closely related to the pathology of many diseases.small molecule biothiols cysteine(Cys),homocysteine(Hcy)and glutathione(GSH)are important bioactive sulfur markers.When Cys is lacking,it can cause growth retardation and hair loss.Abnormal Hcy concentration is a risk factor for cardiovascular disease and Alzheimer's disease.Abnormal GSH concentration is related to diseases such as AIDS and cancer.Hypochlorous acid(HOCl)is an important endogenous biologically active small molecule in reactive oxygen species.Abnormal HOCl concentration may cause cardiovascular disease,cancer and other diseases.Therefore,the detection of biologically active small molecules is of great significance for their generation,function and metabolism in biological systems,and it can also promote the early diagnosis,intervention and treatment of related diseases.In recent years,fluorescent probes and fluorescent imaging techniques have been widely used for the detection and imaging of small molecular compounds in organisms.However,the reported series of probes still have short emission wavelengths,insufficient sensitivity,and poor water solubility,which limits their application in imaging of cells and living organisms.Therefore,we need to develop probes with the advantages of long wavelength,high sensitivity,and good water solubility,which are expected to detect small biologically active molecules in biological systems.In the second chapter,We selected the introduction of 2-mercapto-4,6-dimethoxypyrimidine at the meso position of the cyanine dye to design and synthesize a novel fluorescent probe Cy-S-Py.The probe has the advantages of good water solubility and near-infrared emission.After the probe Cy-S-Py undergoes an aromatic nucleophilic substitution-rearrangement reaction with Cys/Hcy and GSH,Cys/Hcy first reacts with Cy-S-Py to produce sulfur-substituted products(Cy-S-Cys/Cy-S-Hcy),and an intramolecular rearrangement reaction soon takes place to obtain a thermodynamically stable five-or six-membered ring amine substitution products(Cy-N-Cys/Cy-N-Hcy).However,GSH lacking adjacent amine groups cannot cause the intramolecular rearrangement reaction and cannot generate fluorescence.Therefore,Cy-S-Py can detect Cys/Hcy and GSH under the same conditions.At the concentration range of 0?100 ?M,the detection limits of Cys/Hcy for Cy-S-Py are 0.17 ?M and 0.32 ?M,respectively.In addition,the probe's fluorescence emission wavelength reaches the near-infrared region and has good cell membrane permeability,which can turn on fluorescence in Cys/Hcy in cells and living mice.These results confirm that the strategy has broad prospects for studying the biological processes related to Cys/Hcy in complex living systems.In the third Chapter,We used N,N-dimethylaminothioformyl as the protective group of 7-hydroxy-3-phenoxazinone to construct a fluorescent probe RF1 for detecting HOCl.After the reaction between the probe RF1 and HOCl,the Cl~+ of HOCl and the thiocarbamate sulfide undergo an electrophilic addition reaction and an intramolecular cyclization series reaction to remove the dimethylamino thioformyl protecting group.(De-protection),re-releasing resorufin,realizing a change in fluorescence from "none" to "yes".The probe RF1 is able to respond quickly to HOCl within 4 s,and the fluorescence emission peak at 586 nm gradually increases and the fluorescence intensity is increased by about 400 times.When the concentration range is 0?10 ?M,the detection limit of HOCl by RF1 is lower than 1.4 n M.In addition,the probe can not only monitor exogenous HOCl in He La cells in real time,but also track endogenous HOCl in RAW264.7 cells.