Keywords: tricalcium phosphate, hydroxyapatite, hydrolysis, biphasic calcium phosphate, nanotechnology, bone grafting materials, bone reconstruction, bioactivity, biocompatibility, osteoconductivity, microstructure, bone bonding, implants
Synthesis of biphasic calcium phosphate powders by a simple hydrolysis process
An ideal bone grafting material should be compatible with physiological environment, provoke osseous tissue formation and adapt degradation behaviour to new bone tissue growth. Calcium phosphates, a main inorganic constituent of the human hard tissue, are by far the best substitute materials for bone reconstruction because of their excellent bioactivity, biocompatibility and osteoconductivity. In the regime of calcium phosphates, hydroxyapatite (Ca10(PO4)6(OH)2, HA) possesses high stability and chemical similarity to the bone minerals. However, its limited solubility, and hence limited dissolution rate, may cause mismatch between implant and newly born tissue. On the contrary, β–tricalcium phosphate (β–Ca3(PO4)2, β–TCP) undergoes too fast dissolution to form bone bonding. In order to achieve an optimised degradation rate, HA/β–TCP biphasic calcium phosphate (BCP) provides a suitable pathway. The HA/β–TCP ratio in the BCP is critical for desired performance. Unfortunately, the ease of a controllable HA/β–TCP ratio has not been realised. In this study, we report a simple method to synthesise BCP from a monocalcium phosphate monohydrate (Ca(H2PO4)2·H2O, MCPM) precursor. Phase identification, microstructural observations and elemental analysis of the as–synthesised BCP particles are conducted by using X–ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), environmental scanning electron microscopy (ESEM) and X–ray fluorescence (XRF).