Synthesis And Properties Of Viscosity Probes With Biological Targeting

There are various organelles in cells,including mitochondria,lysosomes,lipid droplets,endoplasmic reticulum,and Golgi apparatus.These organelles coordinate with each other to maintain the normal functioning of cells.Organelles have different structures and special microenvironments adapted to their functions.For example,lysosomes have a low p H value as they are involved in the digestion and breakdown of cells.The viscosity between different organelles in cells is also non-uniform.The disturbance of dynamic equilibrium in the local microenvironment of cells may affect the normal functioning of organelles,thereby affecting the function of cells and even organisms,leading to the occurrence and development of diseases.Viscosity,as an important microenvironmental parameter that affects the diffusion of active substances,signal transduction,and electron transfer,is closely related to cell functions such as oxidative stress,autophagy,and apoptosis.Abnormal fluctuations in viscosity may lead to diseases such as cancer,diabetes,and Alzheimer’s disease.The development of viscosity probes with organelle-targeting functions is of great significance for understanding the physiology and pathology related to diseases.Currently,many viscosity probes have been developed for disease diagnosis,but due to the lack of specificity,most probes cannot directly target lesions and have reduced signal-to-noise ratios,making it difficult to distinguish different types of cells.Therefore,the development of biologically targeted fluorescent probes is of great value for exploring the pathogenesis of diseases.In this thesis,we developed two biologically targeted viscosity probes using a specific mitochondrial targeting group,pyridinium cation,and a biological marker,biotin.The main aspects of this research are as follows:1.We developed a near-infrared viscosity probe,DHX-Py-Mor,based on a dihydrooxazine anthracene fluorescent group.The pyridinium cation in the probe enables specific accumulation in mitochondria,and the introduction of the morpholine group does not affect the probe’s mitochondrial localization ability.DHX-Py-Mor has excellent viscosity response ability,and is not affected by polarity,p H,or other active interfering species in the complex microenvironment.The probe was successfully used to monitor real-time changes in mitochondrial viscosity in the iron death model treated with Erastin and to detect fluctuations in mitochondrial viscosity at the organ and cellular levels in inflammatory mice and organ injury mice models,providing a reliable tool for visualizing the physiological and pathological processes related to mitochondrial-related diseases.2.We constructed a tumor-targeted viscosity probe DHX-Bio-Mor by coupling biotin with a molecular rotor based on 4-pyridylacetonitrile through a click reaction.Cancer cells have a high expression of biotin receptors on the cell membrane,and the introduction of biotin enables the probe to enter cancer cells specifically through receptor-mediated endocytosis.The probe has the advantages of low cytotoxicity,p H stability,and specific response to viscosity without interference from other bioactive species.As the proportion of glycerol in the glycerol and PBS buffer system increases,the fluorescence intensity of the probe at 750 nm has a good linear relationship with viscosity.The probe can successfully identify cancer cells and normal cells and monitor changes in viscosity inside cancer cells,providing a powerful tool for exploring the pathogenesis and physiological and pathological processes of cancer.