Study On The Nano-hydroxyapatite And β-Tricalcium Phosphate Compound As Bone Restorative Material

Nanohydroxyapatite (nHA) is one of the bone repairing materials which has good biocompatibility. It could be compatible well with bone tissue interface, induce the new bone tissue growth when implanted in human body as repair materials; β-tricalcium phosphate (P-TCP) is a biodegradable and biological absorbable ceramic materials which has great biological activity. However, it degrades so fast that cannot match the formation of new bone. Consequently, nHA is offen mixed with P-TCP in order to impede the quick degradation of β-TCP and make full use of the osteoinduction of nHA.This research started from the preparation of hydroxyapatite nanoparticles with the sol-gel method which could easily control stoichiometric ratio. The Ca(NO3)4-4H2O/(NH4)2HPO4reactants was selected as reaction system. The fine, pure and well-distributed powder was synthesized through the adoption of appropriate control factors in sol reaction, drying, calcination, etc. Then the effects of synthesis conditions were analyized with XRD, SEM, TEM and FTIR. The results showed that the spherical particles which size is about30nm could be prepared when the reactant concentration is0.3mol/L, the calcination temperature is900℃and some dispersant which is polyethylene glycol is added.Mechanical milling and compression moulding was adopted to mix nHA with P-TCP in accordance with the ratio of constituents60/40, and the pore-forming agent and bonding agent were added in the powder to mold. Finally, the porous blocks which were similar to human bone tissue structure were prepared after calcination and:he main physical and chemical properties were tested.The composite porous materials could be used to repair defected bone. According to the relevant standard of GB/T16886, the biological properities of compound ceramic materials were evaluated including the hemolysis test, stimulation est, acute toxicity test and bone degradation experiment. The results showed that the lemolysis rate of materials was less than5%which cause no hemolysis and the naterials has no cytotoxicity and skin irritation response. There was new bone brmation and materials degradation in the defected parts, indicating that the:omposite materials is available for the repairing of defected bone and could promote he formation of new bone tissue.