Control in Mineralization by the Polysaccharide-Coated Liposome via the Counter-Diffusion of Ions

We created an organic–inorganic hybrid nanocapsule by utilizing polysaccharide-coated liposomes as a reaction site for the deposition of calcium phosphate (CaP). Phosphate ions were encapsulated in a liposome, followed by the layer-by-layer deposition of chitosan (CHI), dextran sulfate (DXS), or DNA onto the liposome surface. Calcium ions were added to an aqueous suspension of the phosphate ion-incorporated nanocapsules to prepare the nanocapsules that provide a variety of walls for the counter-diffusion of ions and the surface for CaP deposition. As a result, control in biomineralization, such as thickness and crystal properties, over the nanocapsules was achieved by tuning the counter-diffusion of the calcium ions and the phosphate ions through the capsule wall and the surface chemical composition of nanocapsules. Furthermore, we carried out DNA adsorption onto CaP-coated liposomes. DNA was releasable from the nanocapsules because of the dissolution of CaP under acidic conditions.