This Small Business Innovation Research Phase I project will develop processes and controls for producing commercial quantities of nanostructured hydroxyapatite (HAP) biomaterials suitable for load bearing orthopedic and dental applications. Though hydroxyapatite's osteoconductivity has generated interest in many clinical applications, conventionally processed hydroxyapatite materials have been limited by their poor sinterability and lack of mechanical strength attributed to poor phase purity and homogeneity. By controlling physical processes such as the method of mixing of reactants, particle recovery and synthesis conditions during the chemical precipitation of HAP, the crystallinity, stoichiometry and particle morphology of HAP will be optimized for mechanical strength. Hydroxyapatite optimized for mechanical strength will be nanocrystalline and possess increased chemical and thermal stability; these properties will lead to enhanced sinterability and minimal grain growth. As a result, fully dense, nanocrystalline HAP monoliths possessing superior chemical homogeneity, microstructural uniformity, ultrafine grain sizes and minimized flaw sizes will be achieved. In the final result, the nanocrystalline HAP monoliths produced will provide superior compressive (900 MPa) and bending (200 MPa) strengths as well as fracture toughness (1.3 MPam1/2). Commercially, these nanostructured materials can be formed into constructs and utilized in experimental models commonly employed to validate orthopedic implants. Nanostructured hydroxyapatites will contribute to better osteoblast attachment, proliferation and mineralization
