Nucleation of biomimetic apatite in synthetic body fluids: dense and porous scaffold development

The effectiveness of synthetic body fluids (SBF) as biomimetic sources to synthesize carbonated hydroxyapatite (CHA) powder similar to the biological inorganic phase, in terms of composition and microstructure, was investigated. CHA apatite powders were prepared following two widely experimented routes: (1) calcium nitrate tetrahydrate and diammonium hydrogen phosphate and (2) calcium hydroxide and ortophosphoric acid, but using SBF as synthesis medium instead of pure water. The characteristics of the as-prepared powders were compared, also with the features of apatite powders synthesized via pure water-based classical methods. The powder thermal resistance and behaviour during densification were studied together with the mechanical properties of the dense samples. The sponge impregnation process was used to prepare porous samples having morphological and mechanical characteristics suitable for bone substitution. Using this novel synthesis was it possible to prepare nanosized (≈20 nm), pure, carbonate apatite powder containing Mg, Na, K ions, with morphological and compositional features mimicking natural apatite and with improved thermal properties. After sintering at 1250 °C the carbonate-free apatite porous samples showed a surprising, high compressive strength together with a biomimetic morphology.