W.M. Keck Biomedical Materials Research Laboratory, School of Mechanical and Materials Engineering, Washington State University, Pullman, WA 99164, USA.
Acta Biomater. 2010 Sep;6(9):3782-90. doi: 10.1016/j.actbio.2010.03.016. Epub 2010 Mar 15.
Despite the excellent bioactivity of hydroxyapatite (HA) ceramics, poor mechanical strength has limited the applications of these materials primarily to coatings and other non-load-bearing areas as bone grafts. Using synthesized HA nanopowder, dense compacts with grain sizes in the nanometer to micrometer range were processed via microwave sintering between 1000 and 1150 degrees C for 20 min. Here we demonstrate that the mechanical properties, such as compressive strength, hardness and indentation fracture toughness, of HA compacts increased with a decrease in grain size. HA with 168 +/- 86 nm grain size showed the highest compressive strength of 395 +/- 42 MPa, hardness of 8.4+/-0.4 GPa and indentation fracture toughness of 1.9 +/- 0.2 MPa m(1/2). To study the in vitro biological properties, HA compacts with grain size between 168 nm and 1.16 microm were assessed for in vitro bone cell-material interactions with human osteoblast cell line. Vinculin protein expression for cell attachment and bone cell proliferation using MTT assay showed that surfaces with finer grains provided better bone cell-material interactions than coarse-grained samples. Our results indicate simultaneous improvements in mechanical and biological properties in microwave sintered HA compacts with nanoscale grain size.
尽管羟基磷灰石（HA）陶瓷具有优异的生物活性，但较差的机械强度限制了这些材料的应用，主要将其应用于涂层和其他非承重区域，例如骨移植物。使用合成的 HA 纳米粉末，通过在 1000 至 1150°C 下微波烧结 20 分钟，处理具有纳米到微米范围内晶粒尺寸的致密压块。在这里，我们证明了 HA 压块的机械性能（例如抗压强度、硬度和压痕断裂韧性）随晶粒尺寸的减小而增加。晶粒尺寸为 168 ± 86nm 的 HA 表现出最高的抗压强度 395 ± 42MPa、硬度 8.4±0.4GPa 和压痕断裂韧性 1.9 ±0.2MPa m(1/2)。为了研究体外生物学特性，评估了晶粒尺寸在 168nm 到 1.16μm 之间的 HA 压块与成骨细胞系的体外骨细胞-材料相互作用。使用 MTT 测定法评估细胞附着和骨细胞增殖的 vinculin 蛋白表达表明，具有更细晶粒的表面比粗晶粒样品提供了更好的骨细胞-材料相互作用。我们的结果表明，微波烧结的具有纳米级晶粒尺寸的 HA 压块的机械和生物学性能得到了同时提高。
