Facile Method for Preparing Liposomes by Permeation of Lipid-Alcohol Solutions through Shirasu Porous Glass Membranes

We present a novel and facile approach for preparing monodispersed liposomes simply by permeating lipid-alcohol solutions through Shirasu porous glass (SPG) membranes. This method uses the phenomenon of mixing of two miscible liquids at their interface formed near an SPG membrane surface, which induces spontaneous formation of liposomes. The effects of lipid concentration, pore size of the SPG membrane, and the alcohol used for the lipid solution on the structures and properties of the liposomes are studied. The liposome size is around 120 nm, and the size distribution is narrow, regardless of the lipid concentration, pore size, and alcohol used. However, the alcohol used affects the property of liposomes: An increase in the liposome size is clearly observed in a freezing-thawing treatment when isopropyl alcohol is used as the alcohol, whereas the liposome size is unchanged by the freezing-thawing treatment when ethanol is used.