Fabrication of carbonate apatite pseudomorph from highly soluble acidic calcium phosphate salts through carbonation

Abstract

B-type carbonate apatite (CO3Ap) has recently emerged as an attractive bone scaffold material because it exhibits significantly higher osteoconductivity than its hydroxyapatite analogue. Highly soluble acidic calcium phosphate salts, such as calcium hydrogen phosphate dehydrate (DCPD) and monocalcium phosphate monophosphate (MCPM), are typically used as bone cement and easily produce large calcium phosphate crystals. However, few studies have focused on these salts as precursors despite extensive investigations on the production of CO3Ap. In this study, DCPD and MCPM were converted into CO3Ap by hydrothermal treatment in the presence of at least 0.5 mol/L NaHCO3, which acted as a neutralizer and CO32- releaser. The obtained material maintained precursor morphologies and was therefore regarded as a pseudomorph of DCPD and MCPM mesocrystal structures. This synthetic approach is expected to facilitate the fabrication of shape-controlled CO3Ap compacts from DCPD and MCPM.