Bai Xiao, Sandukas Stefan, Appleford Mark, Ong Joo L, Rabiei Afsaneh
Mechanical and Aerospace Engineering, North Carolina State University, Raleigh, North Carolina 27695.
J Biomed Mater Res B Appl Biomater. 2012 Feb;100(2):553-61. doi: 10.1002/jbm.b.31985. Epub 2011 Nov 28.
Functionally graded hydroxyapatite coatings (FGHA) doped with 1, 3, and 6.5 wt % silver (Ag) have been deposited on Titanium using ion-beam-assisted deposition. Scanning transmission electron microscopy on coating cross sections confirmed the presence of FGHA coating with mostly amorphous layers at the top and mostly crystalline layers toward the coating interface as well as the existence of 10-50 nm Ag particles distributed throughout the thickness of the coatings. Calcium release in phosphate buffered saline solution showed a high release rate of Ca at the beginning of the test, and a gradual decrease in release rate thereafter to a minimum level until day 7. Similarly, the release rate of Ag in ultra pure water was initially high in the first 4 h and then gradually decreased over a 7 days period. Antibacterial tests have shown a reduction in the viability of S. aureus in Ag-doped coatings particularly in samples with higher Ag concentrations of 3 and 6.5 wt %. Cytotoxicity tests using an osteoblast cell line, on the other hand, have demonstrated that the samples with 6.5 wt % Ag have a negative effect on osteoblast cell response, proliferation, and apoptosis as well as a negative effect on protein and osteocalcin production. It is notable that the samples with 3 wt % Ag or less presented minimal cytotoxicity compared with control surfaces. Considering both the antibacterial and cytotoxicity effects, it is suggested that the 3 wt % of Ag in FGHA coatings can be favorable.
采用离子束辅助沉积法，在钛表面沉积了掺杂1%、3%和6.5%（重量）银（Ag）的功能梯度羟基磷灰石涂层（FGHA）。对涂层横截面进行扫描透射电子显微镜观察，证实存在FGHA涂层，其顶部主要为非晶层，靠近涂层界面处主要为结晶层，并且在整个涂层厚度范围内存在10 - 50纳米的银颗粒。在磷酸盐缓冲盐溶液中的钙释放情况表明，测试开始时钙的释放速率较高，此后释放速率逐渐降低至最低水平直至第7天。同样，在超纯水中银的释放速率在最初4小时内较高，然后在7天内逐渐降低。抗菌测试表明，掺杂银的涂层中金黄色葡萄球菌的活力有所降低，特别是在银浓度较高的3%和6.5%（重量）的样品中。另一方面，使用成骨细胞系进行的细胞毒性测试表明，含6.5%（重量）银的样品对成骨细胞的反应、增殖和凋亡有负面影响，对蛋白质和骨钙素的产生也有负面影响。值得注意的是，与对照表面相比，含3%（重量）或更低银的样品表现出最小的细胞毒性。综合考虑抗菌和细胞毒性作用，建议FGHA涂层中银的含量为3%（重量）较为适宜。
