Department of Physical, Earth and Environmental Sciences, University of Siena, Siena, Italy.
Department of Physical, Earth and Environmental Sciences, University of Siena, Siena, Italy.
Aquat Toxicol. 2019 May;210:179-187. doi: 10.1016/j.aquatox.2019.02.022. Epub 2019 Feb 28.
Nanoplastics are recognized as able to interact with other pollutants including heavy metals, and with natural organic matter, with implications for the potential risks to biota. We investigated the interaction of carboxylated polystyrene nanoparticles (PS-COOH NPs) with copper (Cu) and algal exudates (EPS) and how such interaction could affect Cu toxicity towards the freshwater microalga Raphidocelis subcapitata. PS-COOH NPs behavior in the presence of Cu and EPS was determined by dynamic light scattering (DLS), while PS-COOH NPs surface interaction with Cu ions and EPS was investigated by fluorimetric analysis. ICP-MS was used to test Cu ion adsorption to PS-COOH NPs in the presence and absence of algae. The interaction between PS-COOH NPs and the algal cell wall was assessed by fluorescence microscopy. Short- and long-term toxicity tests were carried out in parallel to assess the impact of PS-COOH NPs on algal growth. Results showed altered nanoparticle surface charge and hydrodynamic diameter following algal EPS exposure, supporting the hypothesis of a protein corona formation. In contrast, no absorption of Cu ions was observed on PS-COOH NPs, either in the presence or absence of algae. No differences on algal growth inhibition were observed between exposure to Cu only, and to Cu in combination with PS-COOH NPs, in short-term as well as long-term tests. However, after 72 h of exposure, the adsorption of PS-COOH NPs to algal cell walls appeared to correspond to morphological alterations, revealing potential disturbances in the mitotic cycle. Our findings confirm the ability of PS-COOH NPs to interact with EPS as shown for other nanomaterials. Environmentally realistic exposure scenarios are thus needed for evaluating nanoplastic toxicity, as nanoparticles will not maintain their pristine nature once released into natural media. Prolonged exposure and use of different end-points such as cell morphological changes and EPS production seem more reliable for the investigation of nanoplastic/algal cell interactions which can drive food chain transfer of nanoplastics and ultimately toxicity.
纳米塑料被认为能够与其他污染物（包括重金属）和天然有机物相互作用，这对生物群潜在风险产生影响。我们研究了羧基化聚苯乙烯纳米颗粒（PS-COOH NPs）与铜（Cu）和藻类分泌物（EPS）的相互作用，以及这种相互作用如何影响 Cu 对淡水微藻莱茵衣藻的毒性。通过动态光散射（DLS）测定 PS-COOH NPs 在存在 Cu 和 EPS 时的行为，通过荧光分析研究 PS-COOH NPs 与 Cu 离子和 EPS 的表面相互作用。ICP-MS 用于测试 Cu 离子在有藻类和无藻类时对 PS-COOH NPs 的吸附。通过荧光显微镜评估 PS-COOH NPs 与藻类细胞壁之间的相互作用。同时进行短期和长期毒性测试，以评估 PS-COOH NPs 对藻类生长的影响。结果表明，暴露于藻类 EPS 后，纳米颗粒表面电荷和水动力直径发生变化，支持形成蛋白质冠的假说。相比之下，在有藻类和无藻类的情况下，均未观察到 Cu 离子在 PS-COOH NPs 上的吸收。在短期和长期测试中，仅暴露于 Cu 或 Cu 与 PS-COOH NPs 联合暴露对藻类生长抑制均无差异。然而，暴露 72 小时后，PS-COOH NPs 吸附到藻类细胞壁上似乎与形态改变相对应，揭示了有丝分裂周期的潜在干扰。我们的研究结果证实了 PS-COOH NPs 与 EPS 相互作用的能力，如其他纳米材料所示。因此，需要进行环境现实暴露情景评估以评估纳米塑料毒性，因为纳米颗粒一旦释放到自然介质中，就不会保持其原始性质。延长暴露时间和使用不同的终点，如细胞形态变化和 EPS 产生，对于研究纳米塑料/藻类细胞相互作用更可靠，这些相互作用可以驱动纳米塑料向食物链转移，并最终产生毒性。
