纳米银抗菌作用机制：剂量依赖性促进细菌凋亡

 背景：纳米银具有高效、广谱抗菌性及不易产生耐药性等优点，已成为目前抗菌材料的研究热点，但目前尚不明确其抗菌的确切机制。目的：研究纳米银抵抗细菌生长的机制。方法：采用抑菌环实验检测Ti、TiO₂及载纳米银TiO₂对单克隆大肠杆菌和金黄色葡萄球菌的抑制作用；将大肠杆菌接种于LB液体培养基中，分别加入0，5，10 mg/L的纳米银溶液，检测24 h内的菌液A值，进行琼脂糖凝胶电泳，分析细菌DNA的变化，应用Annexin V和PI双染色，采用流式细胞术检测细菌凋亡。结果与结论：Ti和TiO₂对金黄色葡萄球菌和大肠杆菌无明显抑制现象，在TiO₂管载纳米银材料片周围出现了明显抑菌环。加入纳米银溶液后，大肠杆菌菌液A值明显降低，并且随着加入纳米银质量浓度的增加，降低趋势更明显。加入纳米银溶液后，大肠杆菌的DNA含量明显减少，并且减少程度随加入纳米银溶液质量浓度的增加而增加。加入纳米银后，细菌Annexin V阳性率增加，并且这种增加趋势与加入纳米银的质量浓度呈正比。表明纳米银可通过促进细菌凋亡这一机制来影响细菌生长。中国组织工程研究杂志出版内容重点：生物材料；骨生物材料; 口腔生物材料; 纳米材料; 缓释材料; 材料相容性；组织工程

Antibacterial mechanism of silver nanoparticles: a dose-dependent promotion of cell apoptosis

BACKGROUND: Silver nanoparticles (AgNPs) show strong antibacterial effect and are not easy to have drug resistance. But the antibacterial mechanisms of AgNPs have not been well developed. OBJECTIVE: To explain the antibacterial mechanisms of AgNPs.METHODS: We investigated the influence of Ti, TiO₂ and TiO₂ containing AgNPs on Escherichia coli and Staphylococcus aureus by bacterial inhibition ring test. Escherichia coli was cultured in LB liquid medium with 0, 5, 10 mg/L AgNPs. We measured the absorbance value of bacterial culture. DNA gel electrophoresis was used to study the effect of AgNPs on Escherichia coli DNA. Then we researched the character of apoptosis on Escherichia coli by Annexin V and PI staining, using flow cytometry.RESULTS AND CONCLUSION: The inhibiting effect of Ti and TiO₂ on Escherichia coli and Staphylococcus aureus was not obvious. But the inhibition rings of TiO₂ containing AgNPs to bacteria appeared. The absorbance value of Escherichia coli culture was reduced when Escherichia coli was co-cultured with AgNPs. And this decrease tendency was in direct proportion with AgNPs concentration. AgNPs reduced the amount of DNA of Escherichia coli and this tendency was directly proportional with AgNPs concentration. The Escherichia coli apoptosis rate induced by AgNPs was increased and this tendency was positively correlated to the AgNPs concentration. These results indicate that AgNPs can induce bacterial apoptosis to influence the growth of bacteria.