Due to the increasing use of nanometric cerium oxide in applications, concerns about the toxicity of these particles have been raised and have resulted in a large number of studies. We report here on the interactions between 7 nm anionically charged cerium oxide particles and living mammalian cells. By a modification of the particle coating including low-molecular weight ligands and polymers, two generic behaviours are compared: particles coated with citrate ions that precipitate in biofluids and particles coated with poly(acrylic acid) that are stable and remain nanometric. We find that nanoceria covered with both coating agents are taken up by mouse fibroblasts and localized into membrane-bound compartments. However, flow cytometry and electron microscopy reveal that as a result of their precipitation, citrate-coated particles interact more strongly with cells. At cerium concentration above 1 mM, only citrate-coated nanoceria (and not particles coated with poly(acrylic acid)) display toxicity and moderate genotoxicity. The results demonstrate that the control of the surface chemistry of the particles and its ability to prevent aggregation can affect the toxicity of nanomaterials.

中文翻译：

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纳米氧化铈的体外毒性：涂层的作用和生物流体的稳定性。

由于在应用中纳米氧化铈的使用越来越多，因此人们对这些颗粒的毒性产生了担忧，并进行了大量研究。我们在这里报告7纳米带负电的氧化铈颗粒与活的哺乳动物细胞之间的相互作用。通过修改包括低分子量配体和聚合物的颗粒涂层，比较了两种通用行为：涂覆有在生物流体中沉淀的柠檬酸根离子的颗粒和稳定且保持纳米级的涂覆有聚丙烯酸的颗粒。我们发现，覆盖有两种涂层剂的纳米氧化铈被小鼠成纤维细胞吸收并定位在膜结合的区室中。但是，流式细胞仪和电子显微镜显示，由于沉淀，柠檬酸盐涂层的颗粒与细胞相互作用更强。在铈浓度高于1 mM时，只有柠檬酸盐涂覆的纳米氧化铈（而不是涂覆有聚丙烯酸的颗粒）显示出毒性和中等的遗传毒性。结果表明，颗粒表面化学的控制及其防止聚集的能力会影响纳米材料的毒性。