Feng B, Weng J, Yang B C, Qu S X, Zhang X D
School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu, PR China.
Biomaterials. 2004 Aug;25(17):3421-8. doi: 10.1016/j.biomaterials.2003.10.044.
The titanium surfaces containing calcium, phosphate ions and the carbonate apatite were characterized. The effect of surface chemistry on the initial rabbit osteoblast response on these surfaces was investigated. The cell count and alkaline phosphatase (ALP) specific activity assay were used for biochemical analyses. Scanning electron microscopy was used for morphology observation and in particular X-ray photoelectron spectroscopy (XPS) for surface chemistry characterization. The number of cells adhering to the apatite coating surface was the maximum, the number of cells on the surface containing calcium without phosphate ions was higher than that containing phosphate without calcium, and the number on the unmodified titanium surface was the least. The osteoblasts cultured on the apatite surface exhibited the highest ALP specific activity, next were the ones on the surface containing solely calcium, the lowest were on the unmodified titanium surface. On the substrate surfaces removed of adhered cells, the order of nitrogen amounts detected by XPS was consistent with ones of ALP specific activity and cell number, except for the unmodified titanium surface. For the substrate surfaces removed of adhered osteoblasts, XPS analysis showed that calcium and phosphorous amounts decreased during cell adhesion. After cell culture the Ca2p binding energy (BE) values for apatite coating and the surface containing solely calcium were similar to those of the two surfaces adsorbed bovine serum albumin (BSA). The P2p BE values for the surfaces containing phosphate ions, including the apatite coating and the surface containing solely phosphate ions, showed the same change. But after cell culture the decrease of the P2p BE value for the coating surface was larger than the one for the surface containing solely phosphate ions. Considering the bovine serum albumin adsorption on the same samples, these results indicated that calcium ions on titanium surfaces play a more important role than phosphate ions in initial interactions among culture medium, osteoblasts and titanium surfaces. On the apatite coating surface, calcium ions are active sites for osteoblast adhesion, while calcium and phosphate ions co-exist on titanium surfaces, the former promotes the osteoblast adhesion onto the phosphate sites on titanium surfaces. The cell adhesion was a complicated biological and chemical process relating to surface several elements similar to protein adsorption.
对含有钙、磷酸根离子和碳酸磷灰石的钛表面进行了表征。研究了表面化学对兔成骨细胞在这些表面上初始反应的影响。细胞计数和碱性磷酸酶（ALP）比活性测定用于生化分析。扫描电子显微镜用于形态观察，特别是X射线光电子能谱（XPS）用于表面化学表征。附着在磷灰石涂层表面的细胞数量最多，不含磷酸根离子的含钙表面上的细胞数量高于不含钙的含磷表面，未改性钛表面上的细胞数量最少。在磷灰石表面培养的成骨细胞表现出最高的ALP比活性，其次是仅含钙表面上的细胞，最低的是未改性钛表面上的细胞。在去除附着细胞的底物表面上，除未改性钛表面外，XPS检测到的氮含量顺序与ALP比活性和细胞数量的顺序一致。对于去除附着成骨细胞的底物表面，XPS分析表明，细胞粘附过程中钙和磷的含量降低。细胞培养后，磷灰石涂层和仅含钙表面的Ca2p结合能（BE）值与吸附牛血清白蛋白（BSA）的两个表面相似。含磷酸根离子的表面，包括磷灰石涂层和仅含磷酸根离子的表面，其P2p BE值呈现相同变化。但细胞培养后，涂层表面P2p BE值的下降幅度大于仅含磷酸根离子表面。考虑到相同样品上的牛血清白蛋白吸附情况，这些结果表明，钛表面的钙离子在培养基、成骨细胞和钛表面之间的初始相互作用中比磷酸根离子发挥更重要的作用。在磷灰石涂层表面，钙离子是成骨细胞粘附的活性位点，而当钙和磷酸根离子共存于钛表面时，前者促进成骨细胞粘附到钛表面的磷酸根位点上。细胞粘附是一个复杂的生物和化学过程，与类似于蛋白质吸附的表面多种元素有关。
