Encapsulation and controlled release of biomolecules from silica microparticles

Biomolecules have been encapsulated in silica microparticles for controlled release applications, by destabilisation of aqueous silica precursors in the water droplets of a water-in-oil emulsion. The use of colloidal solutions ( colloids typically in the size range 6 - 20 nm) as silica precursors avoids the detrimental effect of alcohol in the reactant solution. Thus, subtilisin A has been encapsulated with little to no loss in enzymatic activity. The particles are mesoporous, with a well-defined pore-size in the order of the size of most proteins, enabling the molecules to diffuse out of the solid. The release rate can be controlled by adjusting the pore-size of the silica particles.