Fluoridation of synthetic apatite: Effect on the formation of calcium-deficient hydroxyapatite and the properties of porous scaffold

Fluoridated apatite (FHA) has been considered as a promising bone substitute substance due to its promoting cell proliferation and osteoblastic activity. This paper reports on the synthesis of FHAs via chemical precipitation at room temperature with different KF additions. The prepared samples were characterized using various characterization methods. Both PO43- and HPO42- ions were found in Fourier transform infrared (FTIR) spectra. X-ray diffraction (XRD) results show that two kinds of CaHPO4
• 2H2O (DCPD1, DCPD2) mixed with FHA were present in the final products at the lower content of KF addition. However, the amount of DCPD decreased as the increment of KF added, which hints that fluoridation distinctly accelerates the reaction of transforming DCPD into FHA. Meanwhile, 31P magic angle spinning nuclear magnetic resonance (MAS NMR) spectra indicated that the electron density around P nuclei in FHAs changed with F content. The highly interconnected scaffold with small pores nesting inside large ones had been fabricated by using raw FHA powder and behaved in good bioactivity when examined in simulated body fluid (SBF).