Fusion of dipalmitoylphosphatidylcholine vesicles at 4.degree.C

Abstract
Small sonicated dipalmitoylphosphatidylcholine vesicles when incubated at 4.degree. C and high concentrations fuse completely to vesicles about 700-.ANG. diameter in 7 days, and these further fuse to about 950 .ANG. diameter vesicles after 3-4 wk. The 950 .ANG. diameter vesicles are spherical, homogeneous, mostly unilamellar, have an internal aqueous space about 10 times that of small vesicles, and are stable for at least 6 mo. The 950-.ANG. vesicles are characterized by agarose gel chromatography, freeze-fracture EM, trapped volume measurements, differential scanning calorimetry, and diphenylhexatriene fluorescence polarization.