Interaction of polyions with cell-mimetic species: Physico-chemical and biomedical aspects
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abstract
The possibility of recognition and discrimination of relatively large charged supermolecular objects (latex species) by an oppositely charged polyion is demonstrated using a suspension of carboxylated and protein- modified latex particles interacting with the high molecular mass linear polycations including those conjugated with the specific protein (- chymotrypsin). The polycations are strongly adsorbed on the latex surface. Nevertheless, they are able to migrate between the latex species via occasional interparticle contacts. Finally, the interchanging polycations carrying the specific protein are fixed on those latex particles which carry the complementary protein receptor (trypsin inhibitor from soybean). The presence of other proteins does not hinder such interaction. The resulting effect is considered to mimic a physico-chemical aspect of recognition of target cells by macromolecules combined with relatively small molecular vector. Interaction of the target cell membrane with a polycation was simulated using negatively charged liposomes. It was found that polycations adsorbed on the surface of liquid liposomes can cause a significant charge asymmetry in the lipid bilayer due to transmembrane migration of negatively charged lipids from the inner to outer leaflet. At the same time the liposomal membrane integrity can be retained and adsorbed polycations can be replaced from the membrane by recomplexation with polyanion species. The established phenomena may be important for understanding the biological effects of polycations. Negatively charged liquid liposomes were also used to mimic interaction of cells with DNA-polycation and DNA-cationic surfactant complexes used to enhance plasmid DNA translocation. It was found that the complex of DNA with the polycation carrying hydrophobic side groups interacted with the liposomes without dissociation and adsorbed on the liposome surface as a whole.
