INTERACTION OF POLYIONS WITH CELL-MIMETIC SPECIES - PHYSICOCHEMICAL AND BIOMEDICAL ASPECTS

The possibility of recognition and discrimination of relatively large charged supermolecular objects (latex species) by an oppositely charge d polyion is demonstrated using a suspension of carboxylated and prote in-modified latex particles interacting with the high molecular mass l inear polycations including those conjugated with the specific protein (alpha-chymotrypsin). The polycations are strongly adsorbed on the la tex surface. Nevertheless, they are able to migrate between the latex species via occasional interparticle contacts. Finally, the interchang ing polycations carrying the specific protein are fixed on those latex particles which carry the complementary protein receptor (trypsin inh ibitor from soybean). The presence of other proteins does not hinder s uch interaction, The resulting effect is considered to mimic a physico -chemical aspect of recognition of target cells by macromolecules comb ined with relatively small molecular vector. Interaction of the target cell membrane with a polycation was simulated using negatively charge d 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 f rom the inner to outer leaflet, At the same time the liposomal membran e integrity can be retained and adsorbed polycations can be replaced f rom the membrane by recomplexation with polyanion species. The establi shed phenomena may be important for understanding the biological effec ts of polycations. Negatively charged liquid liposomes were also used to mimic interaction of cells with DNA-polycation and DNA-cationic sur factant complexes used to enhance plasmid DNA translocation. It was fo und that the complex of DNA with the polycation carrying hydrophobic s ide groups interacted with the liposomes without dissociation and adso rbed on the liposome surface as a whole.