Preparation of bionanocapsules by the layer-by-layer deposition of polypeptides onto a liposome

Hollow nanoparticles (bionanocapsules) were prepared using liposomes as a template for the layerby-layer deposition of biopolymers. We carried out the alternative deposition of poly-L-lysine (P_Lys) and poly-L-aspartic acid (P_AsP) onto a negatively charged liposome, which was prepared from dilauroyl phosphatidic acid (DLPA) and dimyristoylphosphatidylcholine (DMPC). Efficient separation of nanocapsules from unbound polymers was achieved by ultrafiltration. ζ-Potentials of nanocapsules changed between positive and negative charges at each deposition. FE-TEM revealed that the liposome was covered with a thin polymeric layer. A fluorescent probe, l-hydroxypyrene-3,6,8- trisulfonic acid (HPTS), was encapsulated into nanocapsules. The release of HPTS was suppressed by the polymer deposition, and the release rate was tunable by coverage of the first P_Lys layer and the ratio of DLPA.