粉末冶金法制备的Mg-5Zn-0.3Ca/nHA生物复合材料的体外降解和细胞毒性

摘要

采用纯Mg、Zn、Ca粉末和纳米羟基磷灰石(nHA)粉末,通过粉末冶金方法制备Mg-5Zn-0.3Ca/nHA生物复合材料,研究不同nHA增强相含量(1％、2.5％和5％,质量分数)对Mg-SZn-0.3Ca合金腐蚀性能的影响.通过模拟体液浸泡试验和电化学技术测试其耐腐蚀性.结果显示,添加1％和2.5％的nHA提高镁合金的耐腐蚀性,这是因为生物活性nHA促进稳定的磷酸盐和碳酸盐表面沉积层的形成,从而提高纳米复合材料的耐蚀性.然而,在镁合金中添加更高含量的nHA作为增强相时,表面沉积层的密度增加,导致局部腐蚀产生的气体无法及时排出而聚集在沉积层下,减小层与基体的粘着力,导致耐腐蚀性能下降.对镁合金及其纳米复合材料的间接细胞毒性评价表明其浸提液无细胞毒性,添加1％nHA的纳米复合材料的测试结果与阴性对照组几乎相似.%Mg-5Zn-0.3Ca/nHA biocomposites were prepared from pure Mg,Zn,Ca and nano-hydroxyapatite (nHA) powders by powder metallurgy method.The effect of various mass fractions of nHA (1 ％,2.5％,5％) as reinforcement on the corrosion properties of Mg-5Zn-0.3Ca alloy was investigated.The corrosion resistance of biocomposite samples was investigated by immersion tests and electrochemical techniques in SBF solution.The results showed that the corrosion resistance of Mg alloy was improved by adding 1％ and 2.5％ nHA.Bioactive nHA motivated the formation of stable phosphate and carbonate layers on surface and improved corrosion resistance of nanocomposites.However,addition of large contents of nHA in Mg alloy as reinforcement increased the density of this precipitated layer,so gases produced from localized corrosion were accumulated underneath this layer and decreased its adhesiveness and lowered its corrosion resistance.Indirect cytotoxicity evaluation for Mg alloy and its nanocomposites also showed that their extraction was not toxic and nanocomposite with 1％ nHA indicated almost similar behavior as negative control.