Porous, biphasic CaCO3-calcium phosphate biomedical cement scaffolds from calcite (CaCO3) powder

Calcite (CaCO3) is a geologically abundant material, which can be used as a starting material in producing biomedical scaffolds for clinical dental and orthopedic applications. Bone-filling applications require porous, biocompatible, and resorbable materials. Commercially available CaCO3 powders were physically mixed, for 80-90 s, with an orthophosphoric acid (H3PO4) solution, which was partially neutralized to pH 3.2 by adding NaOH, to form biphasic, micro-, and macroporous calcite-apatitic calcium phosphate (Ap-CaP) cement scaffolds of low strength. The resultant carbonated and Na-doped Ap-CaP phase in these scaffolds crystallographically and spectroscopically resembled calcium hydroxyapatite. Upon mixing CaCO3 powders and the setting solution, carbon dioxide gas was in situ generated and formed the pores. Thus formed scaffolds contained pores over the range of 20-750 mu m. Scaffolds were also converted to single-phase Ap-CaP, without altering their porosity, by soaking them in 0.5 M phosphate buffer solutions at 80 degrees C for 36 h in glass bottles. Soerensen's buffer solution was also shown to be able to convert the calcite powders into single-phase Ap-CaP powders upon soaking at 60-80 degrees C. This robust procedure of synthesizing Ap-CaP bioceramics is simple and economical.