Abstract: A combination of dynamic light-scattering and fluorescence probe techniques was used to study the structure transform of lecithin vesicle with surfactants with different spacer chain lengths. The mechanism of structure transform of vesicle is explored by model and effective packing parameter theory. The results show that the main reason which leads to the structure transform is the change of superficial electric charge and the asymmetric distribution of the surfactant molecular. Furthermore, the structure of surfactant is also one of the reasons. Surfactants with different spacer chain lengths have different effects on the changs of the structure of the vesicle, which turn out to have some rules.

Key words: Quaternary ammonium Gemini surfactant, Lecithin vesicle, Membrane mimetics