Effect of DNA complexation and freeze-drying on the physicochemical characteristics of cationic liposomes

We describe the use of saccharides, such as sorbitol, mannitol, sucrose, maltodextrin, and dextran, as cyoprotectants for freeze-drying cationic liposomes. Saccharides can protect liposomes either by interacting with phospholipid headgroups or by forming an amorphous glass surrounding the vesicles, thus preventing aggregation, mechanical rupture of membrane, fusion of liposomes, and drug leakage. We have particularly considered liposome characteristics, such as size, zeta potential, and ability in complexing DNA, before and after freeze-drying. Our study indicates that cationic liposomes are able to maintain liposome characteristics after lyophilization and rehydration and maintain the ability to complex DNA even if the strength of the interaction forces was of lower intensity with respect to liposomes before lyophilization.