INTEGRITY OF MIXED LIPOSOMES CONTACTING A POLYCATION DEPENDS ON THE NEGATIVELY CHARGED LIPID-CONTENT

Interaction of poly(N-ethyl-4-vinylpyridinium bromide) (PEVP) with mix ed liquid Liposomes, composed of diphosphatidylglycerol (cardiolipin, CL2-) carrying two anionic phosphodiester headgroups and neutral phosp hatidylcholine (PC), was studied. It was shown that integrity of lipos omes in complex with PEVP critically depends on the mole fraction of n egatively charged CL2- headgroups in the liposomal membrane nu = 2[CL2 -]/(2[CL2-] + [PC]). Liposome integrity remains unchanged unless nu ex ceeds 0.3. At higher CL2- content, PEVP adsorption results in disrupti on of liposomes and formation of rather strong nonvesicular PEVP-lipid complexes.