Influences Of Quaternary Ammonium Salts And Coating Film Solvents On The Electroformation Of Vesicles

Because of the similar size and bilayer structure of cells, vesicles can be widely usedas the model of cell membrane and drug carrier. Giant unilamellar vesicles (GUVs) of10-100m can be obtained by the electroformation method, and their size is similar tothe eukaryotic cells. The additive agent, coating method and parameters of electric fieldhave significant influence on the vesicles size, yield, quality and rate when using theelectroformation method. In this paper, we studied the influences of these three aspectson the electroformation of egg phosphatidylcholine (EggPC) vesicles. This paper isdivided into two parts:Firstly, quaternary ammonium salts can be used as preservative, fungicide and it hasanti-tumor activity. Therefore, we introduced a series of quaternary ammonium salts tomix with EggPC and applied electrical field in the formation process of vesicles. Westudied the formation mechanism of vesicles after the quaternary ammonium salts areadded. Meanwhile, we studied the influences of different chain length of quaternaryammonium salts and different electric field conditions on the eletroformation of vesicles.We obtained the most appropriate parameters of the electric field and the optimal chainlength of quaternary ammonium salts for the electroformation of vesicles.It shows that the formation time of vesicles decreases with the increase of the voltageof the AC electric field after the quaternary ammonium salts are added. With theincreasing of the chain length of quaternary ammonium salts molecules, the averagediameter of the catanionic vesicles increases. C16and C18were the optimal quaternaryammonium salts for the electroformation of catanionic vesicles and the diameter of thevesicles was as large as80-200m, Moreover, it is found that the application of buffersolution can diminish the size of vesicles and extend the existence time of catanionicvesicles compared with the distilled water.Secondly, we studied the influence of different coating solvent on the formation ofvesicles. Triply distilled water, ethanol, tetrahydrofuran, acetone, methanol, propanol,n-butyl alcohol were used as solvent to prepare EggPC film. We systematically studiedthe influences of different solvents, electric conditions and different ratio of solvents on the formation of GUVs. Then the optimum coating solvent which is also economic andenvironmentally friendly for the electroformation of vesicles is obtained.It shows that the optimal coating solvent is ethanol-water mixed solution, and thebest volume ratio of water to ethanol are both1:1and1:2. The optimal electric fieldcondition is5V,20Hz. The operation process using ethanol is simple and convenient.Vesicles made by this method can exist a longer time, meanwhile, it removed the use ofsome toxic solvent such as chloroform and methyl in the experiment process, so thismethod is conducive to expand the application range of the vesicles.