The influence of morphology on the biological effects of nanomaterials (NMs) has not been well understood. In the present study, we compared the phytotoxicity of rod-shaped nano-cerium dioxide (R-CeO2) and nano-cerium phosphate (R-CePO4) to lettuce plants. The results showed that R-CeO2 significantly inhibited the root elongation of lettuce, induced oxidative damages, and caused cell death, while R-CePO4 was nontoxic to lettuce. The different distribution and speciation of Ce in plant tissues were determined by transmission electron microscopy (TEM) and X-ray absorption near edge spectroscopy (XANES) combined with linear combination fitting (LCF). The results showed that in the R-CeO2 group, part of Ce was transformed from Ce(IV) to Ce(III), while only Ce(III) was present in the R-CePO4 group. When interacting with plants, R-CeO2 is easier to be dissolved and transformed than R-CePO4, which might be the reason for their different phytotoxicity. Although both are Ce-based NMs and have the same morphology, the toxicity of R-CeO2 seems to come from the released Ce3+ ions rather than its shape. This research emphasizes the importance of chemical composition and reactivity of NMs to their toxicological effects.

中文翻译：

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棒状纳米CeO2和纳米CePO4对生菜的毒性比较。

形态对纳米材料 (NM) 的生物学效应的影响尚未得到很好的理解。在本研究中，我们比较了棒状纳米二氧化铈 (R-CeO2) 和纳米磷酸铈 (R-CePO4) 对莴苣植物的植物毒性。结果表明，R-CeO2显着抑制生菜根系伸长，诱导氧化损伤，引起细胞死亡，而R-CePO4对生菜无毒。通过透射电子显微镜（TEM）和X射线吸收近边缘光谱（XANES）结合线性组合拟合（LCF）确定植物组织中Ce的不同分布和形态。结果表明，在R-CeO2组中，部分Ce由Ce(IV)转化为Ce(III)，而R-CePO4组中只有Ce(III)存在。与植物互动时，R-CeO2比R-CePO4更容易溶解和转化，这可能是它们药害不同的原因。虽然两者都是基于 Ce 的 NMs 并且具有相同的形态，但 R-CeO2 的毒性似乎来自释放的 Ce3+ 离子而不是其形状。这项研究强调了 NM 的化学成分和反应性对其毒理学效应的重要性。