Fabrication of carbonate apatite blocks from octacalcium phosphate blocks through different phase conversion mode depending on carbonate concentration

Yuki Sugiura, Kunio Ishikawa

Research output: Contribution to journalArticle


Carbonate apatite (CO3Ap) is an inorganic component of mature bone and is used as bone substitute instead of autografts. Recently, 100% pure CO3Ap granules formed from calcium carbonate via a dissolution-precipitation reaction have been used as a clinical precursor for bone. In this study, the feasibility of fabricating blocks of CO3Ap from blocks of octacalcium phosphate (OCP), which is an analog of the bone composition and serves as a precursor for bone, was investigated by immersion in NaHCO3. The macroscopic structure of the OCP block was retained upon conversion to CO3Ap. In addition, as the NaHCO3 concentration increased from 0.0 to 2.0 mol/L, the carbonate content increased in the resulting CO3Ap, reaching ≈ 14 wt% at maximum NaHCO3 concentration. Moreover, the morphology of the CO3Ap crystals varied as the NaHCO3 concentration increased up to 0.5 mol/L: they were pseudomorphic plate-like when the NaHCO3 concentration was low but formed particles ranging ~ 10 nm in size at high NaHCO3 concentrations. The different phase transformation modes depended on NaHCO3 concentrations closely related to CO3Ap crystal morphology and were associated with a decrease in the mechanical strength of the block.

Original languageEnglish
Pages (from-to)85-91
Number of pages7
JournalJournal of Solid State Chemistry
Publication statusPublished - Nov 2018


All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Ceramics and Composites
  • Condensed Matter Physics
  • Physical and Theoretical Chemistry
  • Inorganic Chemistry
  • Materials Chemistry

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