FORMATION AND CHARACTERIZATION OF LIPOSOMES FROM LIPID PROTEIC MATERIAL EXTRACTED FROM PIG STRATUM-CORNEUM/

The formation and physicochemical properties of liposomes prepared fro m a mixture of lipids and proteins extracted from pig stratum corneum have been investigated. The extraction of this material was carried ou t with chloroform/ methanol mixtures. The sonication of these mixtures at 80 degrees C in water that contained piperazine-1,4-bis(2-ethanesu lfonic acid) led to the formation of bilayered structures (vesicle siz e of about 150 nm), which were stable to aggregation for more than 24 h. The interaction of these liposome suspensions (proteoliposomes) at a subsolubilizing level with surfactants indicates that the non- ionic surfactant Triton X-100 had the largest capacity for altering liposom e permeability, whereas the amphoteric surfactant dodecyl betaine exhi bited the smallest. The anionic surfactant sodium dodecyl sulfate show ed an intermediate activity relative to that shown by the other surfac tants tested. Despite the fact that the proteoliposomes showed negligi ble permeability in the absence of surfactants, compared with that of phosphatidylcholine liposomes, addition of identical amounts of surfac tants resulted after 45 min in similar permeability effects for both. However, the proteoliposomes appeared to be more resistant to the acti on of surfactants in the initial interaction period.