摘要

使用模型聚苯乙烯纳米粒子（PS NPs），阴离子（PS-COOH）和阳离子（PS-NH2）的纳米塑料的影响已经在海洋轮虫Brachionus plicatilis（海洋浮游动物物种的主要组分）上进行了研究。在高离子强度介质中已经考虑了不同表面电荷在影响PS NP行为和毒性中的作用。为此目的，选定的媒体是标准化的再生海水（RSW）和天然海水（NSW），后者类似于更自然的暴露场景。使用在RSW和NSW制备的PS NP悬浮液，将孵化的轮虫幼虫暴露于0.5-0.5μg/ ml的两种PS NP中24小时和48小时。尽管在所有暴露的轮虫中明显存在明显的肠道保留，但观察到暴露于阴离子NP时对致死率没有影响。相反，阳离子NPs对轮虫幼虫造成致死性，但与在NSW中暴露的那些（LC50 = 6.62±0.87μg/ ml）相比，LC50值导致RSW中暴露的轮虫（LC50 = 2.75±0.67μg/ ml）更低。 PS NPs在高离子强度介质（RSW和NSW）中显示出相似的聚集模式，但是阴离子NPs产生大的微尺度聚集体（Z-平均分别为1109±128nm和998±67nm），阳离子NP聚集体仍然是纳米尺寸形式（93.99±11.22nm和108.3±12.79nm）。 PS NPs的PDI和Z-电位在两种介质中略有不同，表明它们的不同表面电荷在影响它们的行为和稳定性方面的作用。我们的研究结果证实了表面电荷在盐水介质中纳米塑性行为中的作用，并提供了使用人工培养基（RSW）与天然植物（NSW）相比对轮虫进行不同毒性的第一个证据。这些证据提出了如何在标准化生态毒性测定中选择最佳培养基的问题，以便在自然环境情景中正确评估其对海洋生物的危害。

The impact of nanoplastics using model polystyrene nanoparticles (PS NPs), anionic (PS-COOH) and cationic (PS-NH2), has been investigated on the marine rotifer Brachionus plicatilis, a major component of marine zooplanktonic species. The role of different surface charges in affecting PS NP behaviour and toxicity has been considered in high ionic strength media. To this aim, the selected media were standardized reconstituted seawater (RSW) and natural sea water (NSW), the latter resembling more natural exposure scenarios. Hatched rotifer larvae were exposed for 24h and 48h to both PS NPs in the range of 0.5-50μg/ml using PS NP suspensions made in RSW and NSW. No effects on lethality upon exposure to anionic NPs were observed despite a clear gut retention was evident in all exposed rotifers. On the contrary, cationic NPs caused lethality to rotifer larvae but LC50 values resulted lower in rotifers exposed in RSW (LC50=2.75±0.67µg/ml) compared to those exposed in NSW (LC50=6.62±0.87µg/ml). PS NPs showed similar pattern of aggregation in both high ionic strength media (RSW and NSW) but while anionic NPs resulted in large microscale aggregates (Z-average 1109 ± 128nm and 998±67nm respectively), cationic NP aggregates were still in nano-size forms (93.99 ± 11.22nm and 108.3 ± 12.79nm). Both PDI and Z-potential of PS NPs slightly differed in the two media suggesting a role of their different surface charges in affecting their behaviour and stability. Our findings confirm the role of surface charges in nanoplastic behaviour in salt water media and provide a first evidence of a different toxicity in rotifers using artificial media (RSW) compared to natural one (NSW). Such evidence poses the question on how to select the best medium in standardized ecotoxicity assays in order to properly assess their hazard to marine life in natural environmental scenarios.

https://www.ncbi.nlm.nih.gov/pubmed/28800530