Experimental Study On Liposome Preparation And Electrofusion

Liposomes are structures of lipid molecules arranged in a bilayer configurationforming a spherical shell around an aqueous core. Liposomes are amphiphilic andbiocompatible vesicles which have similar structure as cells and cellular organs.Liposomes are commonly used in foods, cosmetic, medicine industry and biochemicalresearch. Large liposomes whose diameter are larger than1μm are commonly used astools for transfection and cellular functional characterization, and also are goodbiomimetic reactors to reaearch inner biochemical reaction, structure and function ofcell membrane and mechanism of membrane perforation and fusion.There are severalmethods of large liposomes preparation, such as film hydration method, electric fieldmethod, two-phase evaporation method and microfluidic method, and so on.Liposome fusion technology can start reactions in micro-scale to mimeticbiochemical reactions in cells or cellular organs. Besides, it’s significant for theresearch on gene transfection, organelles monitoring, drug fixed-point transmission andbiophysical research on celluar membrane protein, and can serve as cellular model inresearch of membrane fusion. The research on liposome fusion has experiencedCa2+-promoting method, liposome fusion in bulk reactors, micro-operation&electricpulsing method. Compared to the others, micro-operation and electric pulsing methodcan fuse liposome in a controllable way, and it is advantaged for precise operation, highfusion rate, but it still has some disadvantages, such as expensive equipment,complicated operation, time-consuming, etc. Recently, a method based onmicroelectrode chip has been proposed. Our group has carried out study onelectrofusion chip, and high-throughput cell electrofusion was implemented on thesechips. In order to develop microelectrode chip for liposome fusion, liposome fusionexperiments are carried out on available chips in this paper. Kinds of parameters aresummarized for further study on microelectrode chip special for liposome fusion.In this paper, several liposome preparation methods mentioned above are studiedby experiments, and effects of cholesterol content and centrifugation on the stability oflarge liposomes are studied. Finally, large-liposome suspension used for electrofusionexperiments is prepared. And then experimental platform is put up using two kinds ofelectrofusion chip, and several liposome fusion related experiments are done: liposomeparing experiments on the PI based electrofusion chip; liposome paring experiments on the Si-glass based electrofusion chip; liposome electrofusion experiments on theSi-glass based electrofusion chip. In the liposome paring experiment on Si-glass basedchip, high-rate liposomes paring are achieved. In the liposome electrofusionexperiments, liposome fusion is also observed.