Preparation of giant liposomes.

A method is described for the preparation of giant unilamellar lipid vesicles that are stable in electrolyte solution. In general, it involves dialysis of lipid and indifferent solute in a water-miscible organic solvent against an aqueous buffer. During dialysis the concentration of organic solvent decreases so that vesicles form under conditions where their internal contents are continuously hyperosmotic. Interlamellar attractive forces are neutralized, even between bilayer membranes with no net charge, and giant vesicles are generated in large numbers. The population is heterogeneous but most large vesicles have diameters between 10 and 100 micron. The method is simple. One procedure involves dialysis for a day or more of a methanol solution of phosphatidylcholine, supersaturated with methylglucoside, against an aqueous phase containing up to 1 M univalent electrolyte. The procedure is effective over a wide range of temperature and pH.