Reversibility of structural rearrangements in lipid membranes induced by adsorption-desorption of a polycation.

Interaction of poly(N-ethyl-4-vinylpyridinium bromide) with mixed cardiolipin/phosphatidyl-choline (1/9) liposomes was studied by differential scanning calorimetry and photon correlation spectroscopy. It was found that the adsorption of polycation on the surface of liquid liposomes was accompanied by transmembrane migration of negatively charged cardiolipin molecules from the inner to outer membrane leaflet and lateral lipid segregation. At the same time, the liposome integrity was retained, and the adsorbed polycation can be displaced from the membrane by recomplexation with polyanions. As a result, the initial transmembrane and lateral lipid distribution in the membrane was restored.