THE EFFECT OF FORMULATION AND CRYOPROTECTANTON FREEZE-DRIED LIPOSOMES

摘要

The objective of this work was to study and to optimize the conditions of freezing andfreeze-drying process on liposomes. Liposomes coated with polymer have severaladvantages which allow enhancing liposome stability in order to decrease the leakage ofentrapped solute and to improve the cellular uptake of liposomes; naturalpolysaccharides were used to coat the outermost surface of liposomal vesicle. To coat theliposomes by polymers, the methods of nanoprecipiation and emulsion-diffusion wereprepared with the polymer which is not soluble in the aqueous phase (Polycaprolactone).From these results, the size of liposomes was not changed after the incorporation with thewater insoluble polymer (PCL). So, it is possible that the liposome dissolves in theorganic phase. Consequently, Eudragit E100 was selected as a polymer which is solublein the aqueous phase for stabilizing the liposomes. From these results, the sizedistribution was larger than liposomes and nanoparticles of polymer alone. Finally, weperformed the freezing/thawing and freeze-drying the liposome for studying of thestability of freeze-dried liposomes. The liposome coated by Eudragit E100 andliposome alone were not stable after freezing/thawing and after freeze-drying withoutcryoprotectant. Whereas, the liposomes with saccharose or κ-carrageenan were morestables after freeze-drying. The size of liposome incorporated by Eudragit E100 withcryoprotectant was smaller than without cryoprotectant.