Formation of unilamellar lipid vesicles of controllable dimensions by detergent dialysis.

Vesicles are formed by solubilizing mixtures of phosphatidylcholine and cholesterol with sodium cholate and removing the detergent by rapid (hollow fiber) dialysis [e.g., Goldin, S. M. (1977) J. Biol. Chem. 252, 5630--5642]. Characterization of the vesicle size distribution by agarose gel filtration, and determination of the intravesicular aqueous compartment, demonstrates that the vesicles are relatively homogeneous in size and are primarily unilamellar. The mean diameter of the vesicles can be varied from 340 to 1280 A by varying the conditions under which they are formed; increasing the mole fraction of cholesterol and lowering the pH of the dialysate tend to produce larger vesicles. The gentle detergent treatment required for vesicle formation and the ability to control vesicle size distribution reproducibly may make this method particularly useful in studies of reconstitution of membrane proteins and in use of vesicles as vehicles for delivery of materials to living cells.