Study On The Formation Of Vesicle And Its Interaction With Molecules At The Interface With Second Harmonic Generation

In situ monitoring of the self-assembly kinetics of vesicles or other aggregation structures in solution and the structures and kinetic behaviors of drug molecules,functional molecules or materials on the surface of vesicle/liposome membranes is of great scientific significance for the rational design of target nanomaterials with expected properties and a further understanding of the effect of molecules on the biological properties of artificial or living cell membranes.In this thesis,Second Harmonic Generation(SHG)technique with interface selectivity is adopted.The self-assembly kinetics of anionic dye 4-[(4-Butoxyphenyl)diazenyl]benzenesulfonic Acid(BDBSA)with three cationic surfactants was monitored in situ.After mixing anionic dye molecules with cationic surfactant,the detected SHG signal can be effectively related to the aggregate structure formed in the system.The change of SHG signal can also provide information on the formation of asymmetric of phospholipid membrane and the distribution of dye molecules in the complex during self-assembly.In this thesis,Two Photon Fluorescence(TPF)technique was also employed as a spectroscopic method with interface selectivity,combined with SHG technique and theoretical calculation method.The desorption and transfer kinetics of anticancer drug doxorubicin(DOX)on the surface of vesicles were monitored in real time and in situ.The corresponding changes of density,structure and function of DOX at the interface of vesicles were further analyzed.The results show that the fluorescence efficiency of DOX at the lipid membrane interface can be adjusted in the range of 10% to 300% by regulating the molecular adsorption density at the vesicle interface.When the density of DOX at the lipid membrane inte rface is higher,domains can be formed due to the aggregated DOX molecules in the lipid membrane.This will change the permeability of the lipid membrane and induce the transmembrane transport of DOX molecules.In addition,the adsorption and transport behavior of azobenzene molecules with different structures at the interface of phospholipid membrane were studied.The experimental results show that the molecules with hydrophilic groups are more likely to transport across the membrane than those with hydrophobic groups,and there is a significant difference in the transportation rate between them.On the one hand,the self-assembly process of binary composite vesicles is studied by using SHG technology,which provides a theoretical basis for further understanding the molecular self-assembly process and further regulating the target structure.At the same time,it provides a new and effective research method for in situ monitoring of molecular self-assembly process.On the other hand,the kinetic behavior of different molecules at the interface of phospholipid membrane was studied,which is helpful to understand the transfer mechanism of drug molecules from liposome membrane desorption to tumor cell membrane and other target cell membrane.