| The cell microenvironment,including viscosity,pH,hypoxia,polarity,and temperature,etc.not only plays a key role in regulating various biological processes such as cell metabolism,tissue regeneration,and ion transport,but also plays an important role in the normal physiological operation of various organelles.Assure.The imbalance of microenvironmental homeostasis can cause intracellular disorders,leading to organelle dysfunction and disease occurrence.Therefore,accurate detection of the cell microenvironment is of great significance to help humans study various physiological processes in cells and related complex pathologies.With the development of high-sensitivity and non-invasive fluorescence technology,the bottleneck of traditional detection methods of complex cell microenvironment has been broken.Based on this,by modifying the structure of fluorescent dyes and rationally designing three small-molecule fluorescent probes,this paper successfully realized the accurate detection of viscosity,pH and hypoxia microenvironment,and realized the integration of accurate tracking of organelles and cancer diagnosis and treatment.（1）A series of probes S-VP,D-VP and T-VP were developed based on the combination of quinoline derivatives with p-dimethylaminobenzaldehyde and its double bond extension compounds.Probes S-VP and D-VP are sensitive to viscosity due to the existence of double bonds as molecular rotors,so the fluorescence intensity of their emission peaks at 579 nm and 629 nm,respectively,increases gradually with the increase of viscosity.Meanwhile,the protonation of quinoline N atom activates the ICT mechanism under different pH conditions,which responds well to pH,and the fluorescence intensity at 670 nm and 759 nm increases linearly with increasing acidity in the pH range of 3.5-8.0,respectively.The probe T-VP may lose its regular response to viscosity due to the insufficient rigidity of the molecular structure due to the long chain,and the fluorescence quantum yield is too low due to the increase of conjugation,resulting in an insignificant response to pH.By comparing the optical properties of the three probes,the screened probe D-VP is sensitive to viscosity and pH,and the viscosity channel and pH channel emission are relatively longer,which has the advantage of accurate imaging of the microenvironment in vivo.（2）Lipid droplets and lysosomes are important organelles involved in life activities,and lipophagy is an intracellular lipid metabolism process that both lipid droplets and lysosomes participate in.Accurate detection of lipophagy will help to further understand the normal physiological process of cells.Based on the excellent optical properties of the probe D-VP developed in the previous chapter,due to its dual response to viscosity and pH,and a suitable p Ka value of 5.15,it has the possibility of imaging lysosome-related physiological activities.The hydrophobic group N,N-dimethylamine enables the probe to have excellent targeting ability to lipid droplets.Through the imaging study of Hep G2cells,the probe D-VP was successfully realized in the normal state of Hep G2 cells and stimulated by oleic acid.Dynamic tracking of lipid droplets,and further verified the high-precision imaging performance of the probe D-VP for starvation-induced lipophagy.（3）Hypoxia of cells and tissues is a key feature of solid tumors,and the selective treatment of cancer sites still poses a huge challenge to today’s medicine.In this work,based on the mechanism of overexpression of azo reductase（Azo R）induced by hypoxia,which catalyzes the cleavage of azo bonds,an off-on fluorescent probe was designed and synthesized,and the near-infrared DCM-NH2was used as a fluorophore to interact with anticancer through azo bonds.The drug benzodiazepine was linked to the synthetic probe DCM-AD.Under the action of azoreductase,the probe is activated,the fluorophore DCM-NH2is released,and the fluorescence at 669 nm is significantly enhanced.At the same time,the released drug further interacts with the DNA of cancer cells,causing permanent damage to the DNA of cancer cells.The probe DCM-AD successfully achieved accurate imaging of azoreductase in He La cells,and is expected to be further applied to the diagnosis and treatment of cancer in vivo. |
