Porous calcium carbonate microparticles as templates for encapsulation of bioactive compounds

The paper describes the preparation and characterisation of porous calcium carbonate microparticles with an average size of 5 µm and their use for encapsulation of biomacromolecules. The average pore size of about 30–50 nm enables size selective and time-dependent permeation of different macromolecules. Layer-by-layer adsorption of polyelectrolytes into these particles followed by core dissolution leads to formation of interconnecting networks (matrix-like structure) made of polyelectrolyte complexes. The structure can be used for accumulation of bio-macromolecules, mainly proteins. Besides the inter-polyelectrolyte structure templated on porous CaCO3 microparticles the microgel particles (“ghost”) can also be made inside by complexing alginate and calcium. The adsorption of biomacromolecules inside the porous calcium carbonate particles is presumably regulated by electrostatic interactions on the microparticle surface within pores and protein–protein interactions. Protein adsorption into CaCO3 microparticle voids together with layer-by-layer assembly of biopolymers provide a way for fabrication of completely biocompatible microcapsules envisaging their use as biomaterials.