Georgia Electron Microscopy, University of Georgia , Athens, Georgia 30622, United States.
Department of Biomedical Engineering, Georgia Institute of Technology , Atlanta, Georgia 30332, United States.
Environ Sci Technol. 2016 Jul 5;50(13):7082-9. doi: 10.1021/acs.est.6b01172. Epub 2016 Jun 21.
Herein, we detail how the morphology of a nanomaterial affects its environmental lifetime in aquatic ecosystems. In particular, we focus on the cube and particle nanostructures of Ag and age them in various aquatic mediums including synthetic hard water, pond water, and seawater. Our results show that in the synthetic hard water and pond water cases, there was little difference in the rate of morphological changes as determined by UV-vis spectroscopy. However, when these samples were analyzed with transmission electron microscopy, radically different mechanisms in the loss of their original nanostructures were observed. Specifically, for the nanocube we observed that the corners of the cubes had become more rounded, whereas the aged nanoparticles formed large aggregates. Most interestingly, when the seawater samples were analyzed, the nanocubes showed a substantially higher stability in maintaining the nano length scale in comparison to nanoparticles overtime. Moreover, high-resolution transmission electron microscopy analysis allowed us to determine that Ag+ ions diffused away from both the edge and from the faces of the cube, whereas the nanoparticle rapidly aggregated under the harsh seawater conditions.
在此，我们详细介绍了纳米材料的形态如何影响其在水生生态系统中的环境寿命。特别是，我们专注于 Ag 的立方体和颗粒纳米结构，并在包括合成硬水、池塘水和海水在内的各种水介质中对其进行老化。我们的结果表明，在合成硬水和池塘水的情况下，通过紫外可见光谱确定的形态变化速率几乎没有差异。然而，当用透射电子显微镜分析这些样品时，观察到原始纳米结构丧失的机制截然不同。具体来说，对于纳米立方体，我们观察到立方体的角变得更加圆润，而老化的纳米颗粒形成了大的聚集体。最有趣的是，当分析海水样品时，与纳米颗粒相比，纳米立方体在维持纳米长度尺度方面表现出更高的稳定性。此外，高分辨率透射电子显微镜分析使我们能够确定 Ag+离子从立方体的边缘和表面扩散，而纳米颗粒在恶劣的海水条件下迅速聚集。
