Institute of Environmental Sciences (CML), Leiden University, PO Box 9518, 2300 RA, Leiden, the Netherlands.
Institute of Environmental Sciences (CML), Leiden University, PO Box 9518, 2300 RA, Leiden, the Netherlands; College of Environmental Science, Sichuan Agricultural University, Wenjiang, 611130, China.
Environ Pollut. 2020 Jun;261:114117. doi: 10.1016/j.envpol.2020.114117. Epub 2020 Feb 1.
Whether toxicity of silver nanoparticles (AgNPs) to organisms originates from the nanoparticles themselves or from the dissolved Ag-ions is still debated, with the majority of studies claiming that extracellular release of Ag-ions is the main cause of toxicity. The objective of this study was to determine the contributions of both particles and dissolved ions to toxic responses, and to better understand the underlying mechanisms of toxicity. In addition, the pathways of AgNPs exposure to plants might play an important role and therefore are explicitly studied as well. We systematically assessed the phytotoxicity, internalization, biodistribution, and antioxidant responses in lettuce (Lactuca sativa) following root or foliar exposure to AgNPs and ionic Ag at various concentrations. For each endpoint the relative contribution of the particle-specific versus the ionic form was quantified. The results reveal particle-specific toxicity and uptake of AgNPs in lettuce as the relative contribution of particulate Ag accounted for more than 65% to the overall toxicity and the Ag accumulation in whole plant tissues. In addition, particle toxicity is shown to originate from the accumulation of Ag in plants by blocking nutrient transport, while ion toxicity is likely due to the induction of excess ROS production. Root exposure induced higher toxicity than foliar exposure at comparable exposure levels. Ag was found to be taken up and subsequently translocated from the exposed parts of plants to other portions regardless of the exposure pathway. These findings suggest particle related toxicity, and demonstrate that the accumulation and translocation of silver nanoparticles need to be considered in assessment of environmental risks and of food safety following consumption of plants exposed to AgNPs by humans.
银纳米粒子（AgNPs）对生物体的毒性是源于纳米粒子本身还是溶解的 Ag-离子仍存在争议，大多数研究声称细胞外释放的 Ag-离子是毒性的主要原因。本研究旨在确定颗粒和溶解离子对毒性反应的贡献，并更好地了解毒性的潜在机制。此外，AgNPs 暴露到植物中的途径可能发挥重要作用，因此也进行了明确研究。我们系统地评估了根或叶面暴露于不同浓度的 AgNPs 和离子 Ag 后生菜（Lactuca sativa）的植物毒性、内化、生物分布和抗氧化反应。对于每个终点，都量化了颗粒特异性与离子形式的相对贡献。结果表明，AgNPs 在生菜中具有颗粒特异性毒性和摄取，颗粒状 Ag 的相对贡献超过 65%，对整体毒性和整个植物组织中的 Ag 积累有贡献。此外，颗粒毒性源于 Ag 在植物中的积累，通过阻断养分运输，而离子毒性可能是由于过量 ROS 产生所致。在可比暴露水平下，根部暴露比叶面暴露引起更高的毒性。Ag 被发现被吸收并随后从植物暴露的部分转移到其他部分，而不论暴露途径如何。这些发现表明与颗粒有关的毒性，并表明在评估环境风险和人类食用暴露于 AgNPs 的植物后的食品安全时，需要考虑银纳米粒子的积累和迁移。
