Synthesis, characterization and diffusion properties of biomimetic silica-coated gelatine beads

Several micro-organisms are able to coat their surface with a silica deposit exhibiting tailored diffusion properties. In a biomimetic approach, we studied the deposition of silica on gelatine beads. Gelatine capsules were obtained by polymer droplet gelation at low temperature. Soaking of these beads in sodium silicate dilute aqueous solutions leads to the formation of a mineral membrane consisting of close-packed silica nanoparticles. Studies of the diffusion of Rhodamine B and myoglobin indicate that the presence of the silica coating significantly modify the permeability of the beads, suggesting possible applications in controlled release systems.