Rameshbabu N, Sampath Kumar T S, Prabhakar T G, Sastry V S, Murty K V G K, Prasad Rao K
Department of Metallurgical and Materials Engineering, Indian Institute of Technology Madras, Chennai 600036, India.
J Biomed Mater Res A. 2007 Mar 1;80(3):581-91. doi: 10.1002/jbm.a.30958.
The silver (0.5-3 at %) substituted nanosize hydroxyapatites (AgHAs) were synthesized by microwave processing. The X-ray diffraction (XRD) peaks are very broad, indicating that the AgHAs were of nanosize (30 nm). Transmission electron microscopy analysis shows needle-like morphology of AgHA, having length 60-70 nm and width 15-20 nm. The AgHA phase was stable up to 700 degrees C without any secondary phases. The antibacterial effect of AgHA against Escherichia coli and Staphylococcus aureus was observed by spread plate method, even for low concentration of silver ions (0.5%) with 1 x 10(5) cells/mL of respective bacterial culture, after a 48 h incubation period. However, some colonies of E. coli were seen with a high dose of 1 x 10(8) cells/mL after 24 h. The zone of inhibition by disc diffusion test method was found to vary with the amount of silver in the sintered AgHA pellets, for both the bacteria, after 24 h of inoculation. Osteoblast cell attachment in varying density was noticed on AgHA samples with 0.5, 1.0, and 1.5% silver substitution. However, osteoblast spreading was significantly greater on 0.5% AgHA compared to 1.0 or 1.5% substituted AgHA samples. Thus, the low amount of AgHA has a potential of minimizing the risk of bacterial contamination, without compromising the bioactivity, and is expected to display greater biological efficacy in terms of osseointegration.
通过微波处理合成了银（0.5 - 3原子%）取代的纳米尺寸羟基磷灰石（AgHAs）。X射线衍射（XRD）峰非常宽，表明AgHAs为纳米尺寸（30纳米）。透射电子显微镜分析显示AgHA呈针状形态，长度为60 - 70纳米，宽度为15 - 20纳米。AgHA相在高达700摄氏度时稳定，无任何次生相。通过平板涂布法观察了AgHA对大肠杆菌和金黄色葡萄球菌的抗菌效果，即使对于低浓度银离子（0.5%），在各自细菌培养物浓度为1×10⁵个细胞/毫升且培养48小时后。然而，在接种24小时后，对于高剂量1×10⁸个细胞/毫升的情况，仍可见一些大肠杆菌菌落。接种24小时后，通过纸片扩散试验法发现，对于两种细菌，烧结的AgHA颗粒中银含量不同，抑菌圈也不同。在银取代量为0.5%、1.0%和1.5%的AgHA样品上观察到不同密度的成骨细胞附着。然而，与1.0%或1.5%取代的AgHA样品相比，0.5%AgHA上的成骨细胞铺展明显更大。因此，低含量的AgHA有潜力在不影响生物活性的情况下将细菌污染风险降至最低，并有望在骨整合方面展现出更大的生物学功效。
