Objective: This study was designed to analyze the crystal growth of synthetic hydroxyapatite (HA) particles in pH 7.0 supersaturated solutions with different fluoride concentrations by FE-SEM, FE-TEM, X-ray diffraction (XRD), and FTIR. Design: Eight groups of pH 7.0 calcium phosphate supersaturated solutions were prepared with different fluoride concentrations (0, 1, 2, 4, 8, 16, 32, and 64 ppm). Each solution was introduced into the reactive column containing the synthetic HA for 48 h. The resulting products were prepared for FE-SEM, FE-TEM, XRD, and FTIR. Results: The FE-SEM examination revealed various morphological changes of the crystals, with additional, less-ordered crystallites in experimental solutions containing more than 8 ppm of fluoride. FE-TEM examination showed an additional amorphous layer on the surface of the crystals with the presence of fluoride, whereas definite lattice structures completely reached the surface of the crystals without fluorides. XRD data showed that all crystals had the same patterns as the unreacted synthetic HA, regardless of fluoride concentration. With FTIR results, the intensity of the OH-libration mode decreased when adding fluoride, compared to that of pristine HA. The resulting crystals were considered to be partially fluoridated HA under room temperature and pH 7.0 supersaturated solutions. Conclusion: Under the experimental conditions in this study, fluorides mainly react with the surface of the seed HA and have an impact on the growth of HA in a less effective manner as the concentration of fluoride increases.
Bibliographical noteFunding Information:
The authors thank In-Young Kim for her assistance with the analysis of FE-SEM and FE-TEM images and XRD data. The authors declare no potential conflicts of interest with respect to the authorship and/or publication of this article.
© 2019 Elsevier Ltd
All Science Journal Classification (ASJC) codes
- Cell Biology