表面涂层影响铜纳米材料和溶解性铜对大型溞的蓄积动力学和急性毒性

本研究评价了未涂覆或有三种不同表面涂层（即羧基化，聚乙二醇化和氨基团）的氧化铜纳米材料（CuO-NMS）对大型溞（Daphnia magna）的急性毒性和累积动力学。首先利用生物动力学模型确定了溶解铜和CuO-NMS水溶液对大型溞的吸附和消除速率常数。然后评估模型参数与急性毒性终点之间的关系，以考察累积动力学参数是否可作为急性毒性的预测指标。采用朗格缪尔方程表征铜纳米材料和氯化铜（溶解铜对照）的生物吸附动力学。得到的吸收速率依次为：CuO-NMs>NH3-CuO-NMs>Cu水溶液>PEG-CuO-NMs>COOH-CuO-NMs。采用单室模型测定大型溞对铜的去除率。估算了每种被测化学物质的不同消除速率常数。结果显示，容易被生物吸收的物质也更容易从生物体中去除。纳米材料在悬浮液中的吸附和净化性能与Zeta电位值和纳米材料团聚体直径有关。而生物吸附和毒性之间没有联系。水性暴露于较难生物吸附的CuO-NMs比易被生物吸附的CuO-NMs更易诱发不良反应。本文提出了纳米材料在介质中的某些物理化学性质，包括Zeta电位和团聚体直径，可以导致较高的生物吸附，但不一定影响毒性。总而言之，纳米材料与生物体的相互作用模式似乎很复杂，取决于生物体内纳米材料的化学形态和物理化学性质。

Importance of surface coating on accumulation dynamics and acute toxicity of copper nanomaterials and dissolved copper to Daphnia magna.

In this study the effect of copper oxide nanomaterials (CuO NMs), uncoated and with three different surface coatings (i.e. carboxylated, pegylated and ammonia groups), was evaluated on acute toxicity and accumulation dynamics in Daphnia magna. Biosorption and elimination rate constants were determined for D. magna following waterborne exposure to dissolved copper and copper oxide NMs using biodynamic modeling. The relationship between modeled parameters and acute toxicity endpoints was evaluated to investigate if accumulation dynamics parameters could be used as a predictor of acute toxicity. The Langmuir equation was used to characterize the biosorption dynamics of copper NMs and copper chloride, used as dissolved copper control. Uptake rates showed the following ranking: pristine-CuO NMs > NH3-CuO NMs > aqueous Cu > PEG-CuO NMs > COOH-CuO NMs. To determine copper elimination by D. magna a one compartment model was used. Different elimination rate constants were estimated for each chemical substance tested. Those which were easily biosorbed were also easily removed from organisms. Biosorption and depuration properties of NMs were correlated with zeta potential values and diameter of NMs agglomerates in the suspensions. There is no link between biosorption and toxicity. Waterborne exposures to more difficult to biosorb CuO NMs are likely to induce adverse effects more than those which are easily to biosorb. It is proposed that some physicochemical properties of NMs in media, including zeta potential and agglomerate diameter, can lead to higher biosorption but do not necessarily affect toxicity. The mode of interaction of the NMs with the organism, seems to be complex and depends on chemical speciation and physicochemical properties of NMs inside an organism.