Real-time Monitoring Of The Interaction Between Lipid Droplets And Other Organelles With High Signal-to-noise Ratio Fluorescence Probe

Investigating the interactions between lipid droplets(LDs)and other organelles are greatly significant to the in-depth understand the physiology and pathology of LDs.Despite of commercial LDs probes available,the ER and other membrane structures are also stained due to their amphiphilicity,which limits their further applications.To address this issue,we herein report a highly hydrophobic fluorescent probe to specifically label intracellular LDs with high signal/noise ratio,avoiding undesirable stain of ER and thus achieving to real-time monitor the interactions between LDs and other organelles.The probe showed strong emission in lipid environments but no fluorescence in water and liposomes,enabling the probe with high signal/noise ratio.Using this probe,it was found that the contacts of LDs with ER and mitochondria obviously increased under the condition of starvation.In this thesis,we synthesized a fluorescent probe with high signal-to-noise ratio,which can be used to study the interaction between lipid droplets and other organelles in cells.The main contents of this paper are as follows:1.First of all,we designed an extremely hydrophobic fluorescent probe by consulting a large number of literatures.The fluorescent probe uses hydrophobic p-dianisole as the fluorescent parent to modify some hydrophobic groups through double bonds,so that the probe molecules have strong hydrophobic ability.After entering the cells,the probe molecules will be specifically enriched into the lipid environments of the cells because of its hydrophobic nature,and the probes have a relatively high quantum yield in the lipid phase,so the probes will have a strong emission in the lipid droplets.It can be applied to the imaging of lipid droplets in cells.2.Because the probe is a hydrophobic probe,the probe may enter the cell by free diffusion without energy,and the probe has good lipid solubility and can penetrate the cell membrane directly into the cell.When the probe DMQ is in the cytoplasmic matrix,the fluorescence intensity is negligible due to aggregation-induced quenching(ACQ),but when the probe is enriched into the lipid droplets in the cells,the fluorescence intensity of the probe is significantly enhanced.The fluorescent probe can specifically target lipid droplets with high signal-to-noise ratio,and other cellular membranes(such as endoplasmic reticulum,mitochondria,etc.)will not be stained.Thus,the probe molecules can real-time track the physiological activity of intracellular lipid droplets and the interactions between lipid droplets and other organelles.3.Fluorescent probes with high signal-to-noise ratio can be used to explore the interactions between lipid droplets and other organelles.When the cells are under normal conditions,the interactions between lipid droplets and other organelles are not strong,but when the cells are in a state of stress,lipid droplets will interact with other organelles.Such as contact with mitochondria and endoplasmic reticulum.Through the probe reported in this paper,we can monitor the physiological behavior of lipid droplets in cells.