A Novel Technique for the One-Step Preparation of Liposomes and Nonionic Surfactant Vesicles without the Use of Organic Solvents. Liposome Formation in a Continuous Gas Stream: The ‘Bubble’ Method

A novel technique for the preparation of liposomes without the use of organic solvents, detergents, or high shear forces is described. Introduction of inert gas bubbles into a coarse dispersion of nonhydrated (phospho)lipids (hydrogenated soybean phosphatidylcholine and/or dicetylphosphate as charge-inducing agent) or nonionic surfactant (C1 eE03)/cholesterol mixtures produces stable liposome/niosome dispersions with a mean particle size in the range between 0.2 and 0. 5 /μm. The influence of addition of cholesterol and the effect of the ionic strength of the aqueous medium on the preparation process of liposomes was investigated. An hypothesis for the mechanism of liposome formation under the chosen conditions is presented and discussed.