The Preparation of Sugar Polymer-Coated Nanocapsules by the Layer-by-Layer Deposition on the Liposome

We intended to combine the liposomal preparation and the layer-by-layer deposition to prepare a nanosized capsule. Chitosan (CHI) was deposited to form the cationic polymeric layer onto a negatively charged liposomal surface and further deposition was carried out using anionic polymers dextran sulfate (DXS) or deoxyribonucleic acid (DNA). zeta-Potentials of nanocapsules changed between positive and negative charges at each deposition. FE-TEM revealed that the liposome remained a spherical shape even after the layer-by-layer (LbL) deposition. The capsule wall showed it dramatic increase in stability against the surfactant Triton X-100 compared to a bare liposome, and the stability was controllable by the adsorption amount of the polymer. These suggest that the polymer multilayer was generated on the liposome surface by the layer-by-layer depositions of polysaccharides. The three kinds of chemical substances with different charges, I-hydroxy pyrene-3;6,8-trisulfonic acid (HPTS), alendronate, and glucose, were encapsulated into nanocapsules and the release was suppressed by the polymeric capsule wall irrespective of charges. The release from DNA-deposited nanocapsules (liponano-CHI-DNA) was clearly increased by raising temperature from 25 to 60 degrees C. This indicates that the temperature-dependent release was achieved by applying DNA denaturation as a temperature-dependent switch, which influenced the permeability of the capsule wall.