Plants can produce cellular metal nanoparticles (NPs) from the uptake of metal ions, but the mechanism remains unclear. This work reported the new insight into different fates of iron (Fe) and nickel (Ni) ions to transform into the metal NPs in Azolla pinnata roots. After exposing to ferric nitrate, nickel nitrate, and a combination of both for 12 h, the energy dispersive X-ray fluorescence analysis indicated the efficient uptakes of both metal ions in the roots and their transports into the shoots. Transmission electron microscope images revealed the accumulation of spherical FeNPs, but not NiNPs, near the cell wall and cell membrane, and inside vacuoles and multivesicular bodies in cortical and vascular cells at the root tips. The energy dispersive X-ray analysis suggested that the formation of metal NPs depended on the sufficient concentration of metal ions localized in the roots. FeNPs were identified to ɑ-Fe2O3 and Fe3O4 by selected area electron diffraction analysis. The formation of FeNPs might involve the increase of superoxide dismutase activity. This work is the first report about the cellular biogenesis of metal NPs in plant roots that likely depends on cellular metal content and involves the reducing activity of antioxidant enzymes.

中文翻译：

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水绒（满江红）金属纳米颗粒的细胞生物发生：吸收 Fe3+ 和 Ni2+ 转化为纳米颗粒的不同命运。


植物可以通过吸收金属离子来产生细胞金属纳米粒子（NP），但其机制仍不清楚。这项工作报告了对铁 (Fe) 和镍 (Ni) 离子在满江红根中转化为金属纳米粒子的不同命运的新见解。暴露于硝酸铁、硝酸镍和两者的组合12小时后，能量色散X射线荧光分析表明根部有效吸收两种金属离子并将其运输到芽中。透射电子显微镜图像显示，在细胞壁和细胞膜附近以及根尖皮质和血管细胞的液泡和多泡体内部，聚集了球形 FeNP，但没有 NiNP。能量色散X射线分析表明，金属纳米粒子的形成取决于根部局部金属离子的足够浓度。通过选区电子衍射分析，FeNPs被鉴定为ɑ-Fe2O3和Fe3O4。 FeNPs 的形成可能涉及超氧化物歧化酶活性的增加。这项工作是第一份关于植物根部金属纳米粒子的细胞生物发生的报告，该生物发生可能取决于细胞金属含量，并涉及抗氧化酶的活性降低。