Tohda H, Okazaki M, Yanagisawa T, Takahashi J
Department of Ultrastructural Science, Tokyo Dental College, Japan.
Biomaterials. 1995 Aug;16(12):945-50. doi: 10.1016/0142-9612(95)93120-3.
Two different types of heterogeneous fluoridated hydroxyapatites previously synthesized at 80 degrees C and pH 7.4, which might be composed of hydroxyapatite covered with fluorapatite (H-FAp) and fluorapatite covered with hydroxyapatite (F-HAp), were observed by high-resolution transmission electron microscopy. The transverse-sectional shapes of both apatites were clearly hexagonal. This confirmed that both apatites were highly crystallized. However, their shapes differed slightly from each other in detail:H-FAp was more slender and F-HAp was typically hexagonal, probably reflecting the shapes of the original core apatites, hydroxyapatite and fluorapatite. The portions thought to be synthesized with fluoride-free solution showed clear electron beam damage. The expanded lattice image observed at the edge of the F-HAp crystal coincided approximately with the a-axis dimension of 0.9443 nm obtained from the X-ray diffraction data of synthetic hydroxyapatite. After incubation in 0.5 mol l-1 acetate buffer solution (37 degrees C, pH 4.0) for one month, the fluorapatite-covered H-FAp maintained its sharp corners, while the hydroxyapatite-covered F-HAp showed rounded corners.
通过高分辨率透射电子显微镜观察了两种先前在80摄氏度和pH值7.4条件下合成的不同类型的非均相氟化羟基磷灰石，它们可能由氟磷灰石覆盖的羟基磷灰石（H-FAp）和羟基磷灰石覆盖的氟磷灰石（F-HAp）组成。两种磷灰石的横截面形状均为清晰的六边形。这证实了两种磷灰石都高度结晶。然而，它们的形状在细节上略有不同：H-FAp更细长，而F-HAp通常为六边形，这可能反映了原始核心磷灰石（羟基磷灰石和氟磷灰石）的形状。被认为是在无氟溶液中合成的部分显示出明显的电子束损伤。在F-HAp晶体边缘观察到的扩展晶格图像与从合成羟基磷灰石的X射线衍射数据获得的0.9443纳米的a轴尺寸大致相符。在0.5摩尔/升醋酸盐缓冲溶液（37摄氏度，pH值4.0）中孵育一个月后，氟磷灰石覆盖的H-FAp保持其尖角，而羟基磷灰石覆盖的F-HAp则显示出圆角。
