NaCl-induced aggregation of egg phosphatidylcholine liposomes.

Abstract

NaCl-induced aggregations of pure egg phosphatidylcholine liposomes were investigated as a function of NaCl concentration (0-1.5%) by following turbidity changes. The turbidity change seemed to have three stages with increasing salt concentration : Liposomes started aggregation at about 0.01% NaCl and continued mildly up to about 0.15%. At higher levels the turbidity increased sharply. Therefore, the threshold concentration of NaCl is thought to be 0.15%. The turbidity of liposomes swollen in 0.9% NaCl was 3.7 times that when swollen in distilled water. The aggregation phenomena were completely reversible on removing NaCl by dialysis, and the turbidity finally reached the level of the liposomes swollen in distilled water. These phenomena should be borne in mind in the use of neutral liposomes as drug carriers, especially in the reconstitution of lyophilized phospholipids-drug systems.