Biomineral-inspired fabrication of semi-permeable calcium phosphate–polysaccharide microcapsules

Abstract

Mineral–polysaccharide microcapsules are produced by a one-step method in which the deposition of a semi-permeable alginate/chitosan membrane around droplets of sodium alginate is coupled with in situ precipitation of amorphous calcium phosphate. Nucleation of calcium phosphate occurs within the membrane by counter-diffusion of Ca²⁺ and HPO₄²⁻ ions and can be controlled by the phosphate concentration in the alginate droplets to produce hybrid microcapsules with enhanced mechanical strength and reduced permeability to encapsulated molecules such as haemoglobin and ibuprofen.