Preparation and characteristics of lipid vesicles.

As determined by electron microscopy, lipid sonicated in buffer initially forms large vesicles which may be multilamellar. Prolonged sonication results in a population of vesicles of smaller, but not uniform diameters. These vesicles are bounded by only one bilayer. The lipid suspension can be partially fractionated according to size by column chromatography. A fraction of the eluate has been selected for further study. The weight-average vesicle weight and average radius of gyration are obtained by lightscattering measurements. The volume of buffer enclosed by the vesicles is determined using(14)C- or(3)H-labelled sugars as a marker. These values are in reasonable agreement with the corresponding values calculated from the size distribution of the vesicle fraction obtained by electron microscopy.