ИСТИНА

Spherical lipid bilayer vesicles (liposomes) are widely used for delivery of biological active substances. Hydrophilic compounds can be encapsulated into the inner water cavity of liposomes while the hydrophobic can be embedded into the liposomal membrane. We suggest electrostatic assembly of anionic liposomes with the use of polycationic colloid particles and linear polycations for concentration of liposomes within a small volume. This approach allows one to create multiliposomal carriers filled with different substances at desirable content ratios. Small unilamellar liposomes, prepared from mixtures of anionic and zwitterionic lipids, were complexed with “spherical polycationic brushes” (SPB), colloidal particles bearing grafted linear cationic macromolecules on their surface and linear polyelectrolytes polylysine and poly-N-ethyl-4-vynilpyridinium bromide. To control the complexation and properties of the resulting complexes, the multi-method approach was used including fluorescence spectroscopy, dynamic light scattering, laser microelectrophoresis, cryogenic transmission electron microscopy (cryo-TEM); differential scanning calorimetry, conductometry, etc. It was demonstrated that assembly of liposomes on SPBs is more perspective for formation of multiliposomal carriers with desirable composition and colloid stability. The fraction of anionic lipid (α) in liposomes is the critical factor that affects the aggregation stability of liposome/polyelectrolyte complexes, the reversibility of complexation and the integrity of polymer-bound liposomes. Special attention has been paid to structural rearrangements in the liposomal membrane induced by the polycation chains. The difference in structures of interfacial complexes formed by linear polycation and SPB was demonstrated. Complexation of polycations with liposomes allowed us to obtain structures with cytotoxicity close to toxicity of initial biocompatible liposomal vesicles. Acknowledgement This work was supported by Russian Foundation for Basic Research(project 15-33-20880)