Department of Chemical and Biomedical Engineering, West Virginia University , Morgantown, West Virginia 26506, United States.
Health Effects Laboratory Division, National Institute for Occupational Safety and Health , Morgantown, West Virginia 26505, United States.
ACS Appl Mater Interfaces. 2017 Sep 20;9(37):32323-32335. doi: 10.1021/acsami.7b06657. Epub 2017 Sep 5.
Nanoclays' functionalization with organic modifiers increases their individual barrier properties, thermal stability, and mechanical properties and allows for ease of implementation in food packaging materials or medical devices. Previous reports have shown that, while organic modifiers integration between the layered mineral silicates leads to nanoclays with different degrees of hydrophobicity that become easily miscible in polymers, they could also pose possible effects at inhalation or ingestion routes of exposure. Through a systematic analysis of three organically modified and one pristine nanoclay, we aimed to relate for the first time the physical and chemical characteristics, determined via microscopical and spectroscopical techniques, with the potential of these nanoclays to induce deleterious effects in in vitro cellular systems, i.e. in immortalized and primary human lung epithelial cell lines. To derive information on how functionalization could lead to toxicological profiles throughout nanoclays' life cycle, both as-received and thermally degraded nanoclays were evaluated. Our analysis showed that the organic modifiers chemical composition influenced both the physical and chemical characteristics of the nanoclays as well as their toxicity. Overall, when cells were exposed to nanoclays with organic modifiers containing bioreactive groups, they displayed lower cellular numbers as well more elongated cellular morphologies relative to the pristine nanoclay and the nanoclay containing a modifier with long carbon chains. Additionally, thermal degradation caused loss of the organic modifiers as well as changes in size and shape of the nanoclays, which led to changes in toxicity upon exposure to our model cellular systems. Our study provides insight into the synergistic effects of chemical composition, size, and shape of the nanoclays and their toxicological profiles in conditions that mimic exposure in manufacturing and disposal environments, respectively, and can help aid in safe-by-design manufacturing of nanoclays with user-controlled functionalization and lower toxicity levels when food packaging applications are considered.
纳米粘土经有机改性剂功能化后，其个体阻隔性能、热稳定性和机械性能得到提高，并使其易于在食品包装材料或医疗器械中实施。先前的报告表明，虽然层状矿物硅酸盐之间的有机改性剂的整合导致纳米粘土具有不同程度的疏水性，从而易于与聚合物混溶，但它们也可能在吸入或摄入暴露途径中产生潜在影响。通过对三种有机改性和一种原始纳米粘土的系统分析，我们旨在首次将通过显微镜和光谱技术确定的物理化学特性与这些纳米粘土在体外细胞系统中诱导有害作用的潜力联系起来，即永生和原代人肺上皮细胞系。为了了解功能化如何导致整个纳米粘土生命周期的毒理学特征，我们评估了原始和热降解的纳米粘土。我们的分析表明，有机改性剂的化学成分不仅影响纳米粘土的物理化学特性，而且影响其毒性。总体而言，当细胞暴露于含有生物反应性基团的有机改性剂纳米粘土时，与原始纳米粘土和含有长链碳有机改性剂的纳米粘土相比，细胞数量更少，细胞形态更细长。此外，热降解导致有机改性剂的损失以及纳米粘土的尺寸和形状发生变化，这导致在暴露于我们的模型细胞系统时毒性发生变化。我们的研究提供了对纳米粘土的化学成分、尺寸和形状的协同作用以及它们在分别模拟制造和处置环境中暴露的毒理学特征的深入了解，并有助于在食品包装应用中，设计具有用户控制的功能化和更低毒性水平的安全纳米粘土的制造。
