In situ formation of biphasic calcium phosphates and their biological performance in vivo

The co-precipitation technique has been applied to synthesize biphasic calcium phosphate (BCP). After annealing at 900 °C for 24 h, hydroxyapatite (HAp) and β-tricalcium phosphate (β-TCP) were obtained as a single phase at 1.67 and 1.5 Ca/P ratios, respectively. Between these two extremes, a whole range of BCP preparations could be synthesized by using this technique with an accurate control of starting reactants. The biological performance of BCP granulates with a specific content of 62% HAp and 38% β-TCP was investigated. After immersion in Hanks’ balanced salt solution (HBSS) for 1 week, a precipitation started to be formed with individual small granules on the specimen surface. An MTT assay indicated that BCP granulates have no cytotoxic effects on MG-63 cells, and that they have good biocompatibility. An implantation experiment in mouse skulls revealed that BCP granulate provides a strong positive effect on bone formation in vivo in mice.