Butler Kimberly S, Peeler David J, Casey Brendan J, Dair Benita J, Elespuru Rosalie K
U.S. Food and Drug Administration, Office of Medical Products and Tobacco, Center for Devices and Radiological Health, Office of Science and Engineering Laboratories, Division of Biology, Chemistry, and Materials Science, 10933 New Hampshire Avenue, Silver Spring, MD 20993, USA.
U.S. Food and Drug Administration, Office of Medical Products and Tobacco, Center for Devices and Radiological Health, Office of Science and Engineering Laboratories, Division of Biology, Chemistry, and Materials Science, 10933 New Hampshire Avenue, Silver Spring, MD 20993, USA
Mutagenesis. 2015 Jul;30(4):577-91. doi: 10.1093/mutage/gev020. Epub 2015 May 11.
The focus of this research was to develop a better understanding of the pertinent physico-chemical properties of silver nanoparticles (AgNPs) that affect genotoxicity, specifically how cellular uptake influences a genotoxic cell response. The genotoxicity of AgNPs was assessed for three potential mechanisms: mutagenicity, clastogenicity and DNA strand-break-based DNA damage. Mutagenicity (reverse mutation assay) was assessed in five bacterial strains of Salmonella typhimurium and Echerichia coli, including TA102 that is sensitive to oxidative DNA damage. AgNPs of all sizes tested (10, 20, 50 and 100nm), along with silver nitrate (AgNO3), were negative for mutagenicity in bacteria. No AgNPs could be identified within the bacteria cells using transmission electron microscopy (TEM), indicating these bacteria lack the ability to actively uptake AgNPs 10nm or larger. Clastogenicity (flow cytometry-based micronucleus assay) and intermediate DNA damage (DNA strand breaks as measured in the Comet assay) were assessed in two mammalian white blood cell lines: Jurkat Clone E6-1 and THP-1. It was observed that micronucleus and Comet assay end points were inversely correlated with AgNP size, with smaller NPs inducing a more genotoxic response. TEM results indicated that AgNPs were confined within intracellular vesicles of mammalian cells and did not penetrate the nucleus. The genotoxicity test results and the effect of AgNO3 controls suggest that silver ions may be the primary, and perhaps only, cause of genotoxicity. Furthermore, since AgNO3 was not mutagenic in the gram-negative bacterial Ames strains tested, the lack of bacterial uptake of the AgNPs may not be the major reason for the lack of genotoxicity observed.
本研究的重点是更深入地了解影响基因毒性的银纳米颗粒（AgNPs）的相关物理化学性质，特别是细胞摄取如何影响基因毒性细胞反应。评估了AgNPs的基因毒性的三种潜在机制：致突变性、断裂剂性和基于DNA链断裂的DNA损伤。在鼠伤寒沙门氏菌和大肠杆菌的五种细菌菌株中评估致突变性（回复突变试验），包括对氧化性DNA损伤敏感的TA102。所有测试尺寸（10、20、50和100nm）的AgNPs以及硝酸银（AgNO3）在细菌中均无致突变性。使用透射电子显微镜（TEM）在细菌细胞内未发现AgNPs，表明这些细菌缺乏主动摄取10nm或更大尺寸AgNPs的能力。在两种哺乳动物白细胞系Jurkat Clone E6-1和THP-1中评估断裂剂性（基于流式细胞术的微核试验）和中度DNA损伤（彗星试验中测量的DNA链断裂）。观察到微核试验和彗星试验终点与AgNP尺寸呈负相关，较小的纳米颗粒诱导更强的基因毒性反应。TEM结果表明，AgNPs局限于哺乳动物细胞的细胞内囊泡中，未穿透细胞核。基因毒性测试结果和AgNO3对照的作用表明，银离子可能是基因毒性的主要原因，甚至可能是唯一原因。此外，由于AgNO3在所测试的革兰氏阴性细菌艾姆斯菌株中无致突变性，AgNPs缺乏细菌摄取可能不是观察到的缺乏基因毒性的主要原因。
