Novel method for the fabrication of multiscale structure collagen/hydroxyapatite-microsphere composites based on CaCO3 microparticle templates

A synthesis strategy based on the phase transformation of calcium carbonate (CaCO3) microparticle templates was developed for the fabrication of collagen/hydroxyapatite (HA)-microsphere composite materials, which were derived from prefabricated collagen/CaCO3-microparticle hybrid gels in a phosphate ambience. Fourier transform infrared spectroscopy and X-ray diffraction analyses were conducted to confirm the formation of carbonated hydroxyapatite in the collagen/HA-microsphere composites. The variations in the contents of inorganic components after the transformation of CaCO3 templates into calcium phosphate were further validated via thermogravimetric analysis. Scanning electron microscopy characterization revealed the unique multiscale microstructures of the collagen/HA-microsphere composites, which comprised collagen nanofibril networks and HA microspheres. The synthesis strategy is suitable for the in situ synthesis of microscale apatite components within a collagen-based biomacromolecule matrix under mild conditions.

► The concept of CaCO3 templates for HA synthesis has been proposed and demonstrated.
► Hydroxyapatite microspheres can be prepared in collagen matrix under mild conditions.
► These composites exhibit a multiscale structure including nanofibril and microsphere.