Development of mechanically reinforced porous ceramics for bone regeneration

Hydroxyapatite (HA) is widely recognized as suitable material to develop scaffolds for bone regeneration, mainly due to optimal chemical mimicry with the natural inorganic component of bones. Despite such a great potential, a major drawback associated to hydroxyapatite, typical of all ceramic materials, refers to its intrinsic brittleness, posing significant limitation to their clinical use mainly due to the risk of irreparable failure of the scaffolds. This is a major reason making the regeneration of load-bearing bone defects such as maxillofacial regions and spine region, a still unmet clinical need of great socio-economic relevance. Among the various approaches for apatite reinforcement, the use of carbon fibers is an interesting strategy due to their inherent biocompatibility, high strength-to-weight ratio, thermophysical properties, sorption, and high elastic modulus. They can bridge cracks and arrest their propagation, thus raising the toughness and helping to prevent the ceramic scaffold from sudden failure. In this respect, my Ph.D. project is focused on the development of new processes to achieve calcium phosphate-based scaffolds featuring enhanced mechanical properties. The first part of my PhD thesis involves the development of mechanically reinforced porous apatitic ceramic scaffolds obtained by 3D forming of hydroxyapatite powders and sintering. The second part of my PhD activity involves the development of porous apatitic bone cements obtained by isothermal reaction of metastable calcium phosphate precursors at body temperature, mechanically reinforced with carbon fibers. This second part includes three sub-chapters dealing with: i) apatitic cements obtained from inorganic precursors synthesized by low and high-temperature treatments, ii) magnesium-doped apatitic cements with intrinsic antibacterial properties and iii) reinforcement of magnesium and strontium-doped apatitic cements with carbon fibers.