Triangular Phase Diagrams in the Phospholipid−Water−Alcohol System for the Preparation of Lipid Vesicles (Liposomes) Using the Coacervation Technique

The effect of alcohol and electrolytes on simple coacervation in the phospholipid−water−alcohol system is described in detail. The optimal coacervation conditions for formation of lipid vesicles in the phospholipid−water−alcohol system were examined by the triangular phase diagram. Three different alcohols, methanol, ethanol, and 1-propanol, were used as a lipid solvent. Water and various electrolyte solutions such as sodium chloride, ammonium chloride, magnesium chloride, calcium chloride, and sodium sulfate were used as a poor solvent for the lipids. When methanol and 1-propanol were used as lipid solvents, the entire phase resulted in a transparent, highly viscous gel phase. On the other hand, the profile of the coacervate precipitation of the phospholipid was observed when ethanol was used as a lipid solvent. Moreover, when 1-propanol was used as a lipid solvent, a large volume of water phase was required to induce the coacervation in the systems in comparison with methanol or ethanol. The coacervatio...