Construction Of Stimulus-responsive Giant Fluorescent Vesicles And Their Imaging Studies

The design and construction of artificial cells is of great significance in the simulation of life cells,which is helpful to deeply understand the origin of life.Giant vesicles not only have a closed bilayer structure similar to the plasma membrane of all biological cells,but also are similar in size to cells,so they are widely used in biomembrane function simulation research.Meanwhile,giant vesicles are easily observed by optical microscopy imaging systems,making them promising for visual sensing analysis.The current giant vesicle systems are mainly divided into two categories:liposomes and polymer vesicles.There are few types of molecules used to prepare liposomes and are not easy to be further chemically modified.The preparation of polymeric vesicles suffers from drawbacks in reproducibility,membrane fluidity,and permeability.Therefore,it is of great significance to develop novel lipid-like molecular systems and their use in the preparation of giant vesicles.In this paper,three novel zwitterionic surfactants with aggregation-induced emission（AIE）properties have been designed and synthesized using the molecular framework of dodecyldimethyl（3-sulfopropyl）ammonium hydroxide inner salt(C₁₂DAPS)as a model by modifying the tetraphenylethylene（TPE）fluorophore at the end and adjusting the length of hydrophobic tail chain.The giant fluorescent vesicles were successfully prepared in aqueous solution by combining zwitterionic and anionic surfactants with appropriate energy stimulation.The main research contents are as follows:1.A series of sulfonybetaine type zwitterionic surfactants:TPE-C₃DAPS,TPE-C₆DAPS and TPE-C₁₀DAPS,were designed and synthesized by changing the number of carbon atoms in the hydrophobic straight chain（C3,C6 and C10）.The successful synthesis of zwitterionic surfactants was proved by ¹³C NMR,¹H NMR and MS,and the optical properties of zwitterionic surfactants were studied by UV-vis absorption spectrum and fluorescence spectrum.The results showed that the fluorescence emission intensity of this series of molecules increased with the increase of concentration.The hydrophobicity of TPE-C₃DAPS,TPE-C₆DAPS and TPE-C₁₀DAPS was almost unchanged with increasing alkyl chain length.2.Preferably,TPE-C₁₀DAPS was combined with sodium dodecyl sulfate（SDS）to form highly luminescent tubular aggregates by electrostatic and hydrophobic synergistic action.The size and morphology of the composite were characterized by transmission electron microscopy（TEM）,laser scanning confocal microscopy（CLSM）and dynamic light scattering（DLS）.Under the stimulation of microwave heating and UV light irradiation,the tubular aggregates spontaneously transformed into giant spherical vesicles,and the dynamic process of the morphology transformation was visualized in real time by CLSM.In addition,the established method for preparing giant vesicles by mixing TPE-C₁₀DAPS and anionic surfactant has good generality.