Davidson R Andrew, Anderson Donald S, Van Winkle Laura S, Pinkerton Kent E, Guo T
Department of Chemistry and ‡Center for Health and the Environment, University of California , Davis, California 95616, United States.
J Phys Chem A. 2015 Jan 15;119(2):281-9. doi: 10.1021/jp510103m. Epub 2014 Dec 30.
Following a 6-h inhalation exposure to aerosolized 20 and 110 nm diameter silver nanoparticles, lung tissues from rats were investigated with X-ray absorption spectroscopy, which can identify the chemical state of silver species. Lung tissues were processed immediately after sacrifice of the animals at 0, 1, 3, and 7 days post exposure and the samples were stored in an inert and low-temperature environment until measured. We found that it is critical to follow a proper processing, storage and measurement protocol; otherwise only silver oxides are detected after inhalation even for the larger nanoparticles. The results of X-ray absorption spectroscopy measurements taken in air at 85 K suggest that the dominating silver species in all the postexposure lung tissues were metallic silver, not silver oxide, or solvated silver cations. The results further indicate that the silver nanoparticles in the tissues were transformed from the original nanoparticles to other forms of metallic silver nanomaterials and the rate of this transformation depended on the size of the original nanoparticles. We found that 20 nm diameter silver nanoparticles were significantly modified after aerosolization and 6-h inhalation/deposition, whereas larger, 110 nm diameter nanoparticles were largely unchanged. Over the seven-day postexposure period the smaller 20 nm silver nanoparticles underwent less change in the lung tissue than the larger 110 nm silver nanoparticles. In contrast, silica-coated gold nanoparticles did not undergo any modification processes and remained as the initial nanoparticles throughout the 7-day study period.
在对直径为20纳米和110纳米的雾化银纳米颗粒进行6小时吸入暴露后，利用X射线吸收光谱法对大鼠的肺组织进行了研究，该方法可识别银物种的化学状态。在暴露后0、1、3和7天处死动物后立即对肺组织进行处理，样本储存在惰性低温环境中直至测量。我们发现遵循适当的处理、储存和测量方案至关重要；否则，即使对于较大的纳米颗粒，吸入后也只能检测到氧化银。在85K空气中进行的X射线吸收光谱测量结果表明，所有暴露后肺组织中的主要银物种是金属银，而非氧化银或溶剂化银阳离子。结果进一步表明，组织中的银纳米颗粒从原始纳米颗粒转变为其他形式的金属银纳米材料，这种转变的速率取决于原始纳米颗粒的大小。我们发现，直径为20纳米的银纳米颗粒在雾化和6小时吸入/沉积后发生了显著变化，而较大的直径为110纳米的纳米颗粒基本未变。在暴露后的七天内，较小的20纳米银纳米颗粒在肺组织中的变化小于较大的110纳米银纳米颗粒。相比之下，二氧化硅包覆的金纳米颗粒在整个7天的研究期间未发生任何改性过程，仍保持为初始纳米颗粒。
