Development of Mg-containing porous β-tricalcium phosphate scaffolds for bone repair

Apatitic tricalcium phosphate (ap-TCP) powders containing Mg were synthesized through wet chemical precipitation method from CaO and H3PO4, using MgO as the source of Mg substitution. The influence of small, close to bone-like amounts of Mg on the thermal stability and specific surface area (SSA) of as-synthesized ap-TCP powders was evaluated. The increase in Mg content up to 0.674±0.080 wt% promoted enlarging of SSA of the as-synthesized powders between 91.3 m2/g and 104.2 m2/g and the stabilization of the β-tricalcium phosphate (β-TCP) phase up to 1360 °C. The effect of Mg substitution on porosity and microstructure was investigated. Interconnected porous Mg-containing β-TCP scaffolds, with micro-, macroporous structures were developed by an in situ foaming of viscous mass of proper slurry prepared of the as-synthesized ap-TCP powders, using NH4HCO3 as a foaming agent, and subsequent sintering at 1150 °C for 2 h. The self-dissolution behavior in vitro was evaluated through soaking of scaffolds in SBF. The release of Ca and Mg ions from the 3D micro-, macroporous β-TCP scaffolds containing various amounts of Mg was determined by a complexometric (EDTA) titration. The samples with increased Mg concentrations showed significantly enhanced Mg-release rate in comparison to the samples with lower Mg substitution level.