INTERACTION BETWEEN ZINC(II)-PHTHALOCYANINE-CONTAINING LIPOSOMES AND HUMAN LOW-DENSITY-LIPOPROTEIN

The interaction of human low density lipoprotein (LDL) and small unila mellar liposomes containing the photosensitiser zinc(II)-phthalocyanin e (Zn-Pc) was studied in vitro to determine if Zn-Pc could be directly incorporated into the lipoprotein in the absence of other serum compo nents. Incubation of LDL with increasing concentrations of liposomes r esulted in a progressive increase in the net negative charge of LDL as determined by agarose gel electrophoresis and both Zn-Pc and liposoma l phospholipid were incorporated into the modified LDL particles. Gel chromatography experiments indicated an increase in the molecular mass of modified LDL and immunoaffinity chromatography provided evidence t hat apoprotein B epitopes on modified LDL were unable to bind to antib ody. The study indicated that the liposomal components could be select ively incorporated into LDL by a process that did not appear to involv e either aggregation or fusion of particles.