Sintering of magnesium-strontium doped hydroxyapatite nanocrystals: Towards the production of 3D biomimetic bone scaffolds

The development of biomimetic scaffolds is a challenging aim in the field of bone repair for fabrication of osteoconductive and osteoinductive scaffolds. Biogenic hydroxyapatite (HA) is not stoichiometric but is substituted by several ions. An approach to improve synthetic scaffolds biomimetism can be the doping with osteoinductive ions. To this aim, herein thermally stable magnesium-strontium hydroxyapatite (HAMgSr) nanocrystals were synthesized and used for the fabrication of sintered highly porous scaffolds. The chemical and physical properties of the obtained scaffolds were analyzed by X-ray diffraction, scanning electron microscopy, mechanical testing. Three different substituting ions percentage were analyzed and among these, the copresence of Mg and Sr at 0.5 wt% has shown the best results in terms of thermal stability and mechanical properties. The potential utilization of these materials for bone regeneration purposes was preliminarily evaluated in vitro, by assaying proliferation of viable osteoblast-like cells; the experimental evidences suggest that the scaffolds can be exploited as bone-mimicking substrates suitable to support cell growth and proliferation. These observations underline the importance of the presence of Mg and Sr in scaffolds for bone remodeling as well as the good potential of the newly developed scaffolds for clinical use in tissue engineering.