Abstract
Freezing or freeze-drying caused a decrease in the liposome size and an increase in water permeability of large multilamellar liposomes made of phosphatidylcholine and cholesterol (0%, 10%, 33% in mole ratio), but no size reduction with partially-sonicated liposomes. Cold storage at -27°C up to 45 days resulted in no change in water permeability, although the proportion of fragmented liposomes increased. On the other hand, the cold storage caused significant increase in permeabilities of hydrophilic amino acids such as Gly and Pro with phosphatidylcholine multilamellar liposomes. These results indicate that freezing, freeze-drying, and cold storage induce an increase in the structural defect of lipid bilayer as well as increase in mobility (or disorder) of lipid bilayer.
