Study Of The Crystallization Of Calcium Phosphate Powders

Biominerals generally display exquisite morphologies not normally seen in synthetic laboratory preparations. This may be attributable to the bio systems that act to modify or direct crystal growth and assembly. It has been proven that the organized assembly structure can help sustain a more complex mechanical stress, as presented by natural composite materials such as teeth, bones, and shells. So unraveling the formation mechanisms of biominerals in organisms, and mimicking these processes in systems are important to materials research and preparation.Calcium orthophosphates are the main mineral constituents of bones and teeth, and so, synthetic calcium phosphates are excellent biomaterials for bone regeneration. However, the most commonly used calcium phosphates such as hydroxyapatite and (3-tricalcium phosphate have limited in vivo resorption and remodeling capacity, and therefore are unsuitable as bone graft substitutes for vertical bone augmentation. Recent studies have shown that the acidic calcium phosphates, brushite and monetite, are osteoconductive, osteoinductive and resorb faster in vivo than hydroxyapatite, being of great interest for maxillofacial bone augmentation.In this dissertation, we have enriched and further developed the biomimetic approach to synthesize calcium phosphate biomaterials, and studied the crystallization process in both chitosan mediated and ammonia vapor diffusion reaction systems. By these simple and mild methods, calcium phosphates with complex structures were obtained, the fabricated monetite showing orderly layered morphology while brushite being hollow structure. The [Ca]/[P] molar ratio of solution component played important role in this process, through which can promote formation of complex structural materials. This work offers potential strategies for fabricating materials with complex structures.