Fused liposome and acid induced method for liposome fusion

Abstract From the Canadian patent

Liposomes containing phosphatidylethanolamine palmitoyl, homocysteine or oleic acid or palmitic acid fuse rapidly when, the pH of the medium is reduced below 7. Liposome fusion was measured by (a) mixing of the liposomal lipids as shown by resonance energy transfer, (b) gel filtration and (c) electron microscopy. The presence of phosphatidylethanolamine or acid addition esters thereof in the liposomes greatly enhances fusion; whereas the presence of phosphatidylcholine inhibites fusion. During fusion of liposomes oontaining phosphatidylethanolamine:palmitoyl homocysteine (8:2) almost all, of the encapsulated calcein is released. Inclusion of cholesterol (40%) in the liposomes substantially …