SYNTHETIC POLYCATIONS ON THE SURFACE OF NEGATIVELY CHARGED LIPOSOMES

Adsorption of poly-N-alkyl-4-vinylpyridine cations on the surface of n egatively charged liquid and solid phosphatidylcholine-cardiolipin lip osomes was studied. The poly-n-ethyl-4-vinylpyridine cation adsorbed o n the surface of liquid liposomes was found to be completely displaced from the surface into solution by polyacrylate anions, the latter for ming an interpolyelectrolyte complex with the polycation. On the contr ary, the polycation carrying side-chain cetyl fragments forms a more s table complex with liposomes, probably due to the incorporation of cet yl fragments into the lipid bilayer. In this case, the polyanion canno t displace the polycation from the surface, the liposome-polycation-po lyanion ternary complex being formed. Polycation adsorption on the sur face of liquid liposomes induces transbilayer migration of the cardiol ipin molecules from the inner to outer bilayer leaflet. In solid lipos omes, only the outer cardiolipin molecules form a complex with adsorbe d polycations.