Preparation of liposomes with a controlled assembly procedure

A method of liposome preparation that involves two experimental steps is demonstrated. First, water in oil (WIG) emulsions are prepared by sonication. Then, due to centrifugal force, water droplets in the emulsion contact the monolayer at the oil/water interface and transform into liposomes after the monolayer has enwrapped the droplets. This procedure results in liposomes with diameters in the range 50-200 nm. Advantages of this procedure include relatively high (60%) encapsulation efficiency, direct preparation of liposomes in an aqueous medium different from the entrapped phase, and no leakage of the encapsulated chemicals during preparation. This relatively simple and rapid method may be useful in the encapsulation of drugs, enzymes, and other macromolecules as well as in the study of membrane properties. (C) 1997 Academic Press.