Bioengineering, University of California, Merced, Merced, California, United States of America.
PLoS One. 2011;6(7):e21865. doi: 10.1371/journal.pone.0021865. Epub 2011 Jul 21.
The unique properties of engineered nanoparticles (ENs) that make their industrial applications so attractive simultaneously raise questions regarding their environmental safety. ENs exhibit behaviors different from bulk materials with identical chemical compositions. Though the nanotoxicity of ENs has been studied intensively, their unintended environmental impacts remain largely unknown. Herein we report experimental results of EN interactions with exopolymeric substances (EPS) from three marine phytoplankton species: Amphora sp., Ankistrodesmus angustus and Phaeodactylum tricornutum. EPS are polysaccharide-rich anionic colloid polymers released by various microorganisms that can assemble into microgels, possibly by means of hydrophobic and ionic mechanisms. Polystyrene nanoparticles (23 nm) were used in our study as model ENs. The effects of ENs on EPS assembly were monitored with dynamic laser scattering (DLS). We found that ENs can induce significant acceleration in Amphora sp. EPS assembly; after 72 hours EN-EPS aggregation reached equilibrium, forming microscopic gels of ∼4-6 µm in size. In contrast, ENs only cause moderate assembly kinetic acceleration for A. angustus and P. tricornutum EPS samples. Our results indicate that the effects of ENs on EPS assembly kinetics mainly depend on the hydrophobic interactions of ENs with EPS polymers. The cycling mechanism of EPS is complex. Nonetheless, the change of EPS assembly kinetics induced by ENs can be considered as one potential disturbance to the marine carbon cycle.
工程纳米粒子（ENs）具有独特的性质，使其工业应用极具吸引力，但同时也引发了人们对其环境安全性的关注。ENs 表现出与具有相同化学成分的块状材料不同的行为。尽管已经对 ENs 的纳米毒性进行了深入研究，但它们对环境的潜在影响在很大程度上仍未可知。本文报告了工程纳米粒子与三种海洋浮游植物（Amphora sp.、Ankistrodesmus angustus 和 Phaeodactylum tricornutum）的胞外聚合物（EPS）相互作用的实验结果。EPS 是各种微生物释放的富含多糖的阴离子胶体聚合物，可能通过疏水和离子机制组装成微凝胶。本研究中使用聚苯乙烯纳米粒子（23nm）作为模型 ENs。通过动态激光散射（DLS）监测 ENs 对 EPS 组装的影响。结果发现，ENs 可以显著加速 Amphora sp. EPS 的组装；72 小时后，EN-EPS 聚集达到平衡，形成大小约为 4-6μm 的微观凝胶。相比之下，ENs 仅对 A. angustus 和 P. tricornutum EPS 样品的组装动力学产生适度的加速作用。研究结果表明，ENs 对 EPS 组装动力学的影响主要取决于 ENs 与 EPS 聚合物之间的疏水相互作用。尽管 EPS 的循环机制很复杂，但 ENs 诱导的 EPS 组装动力学的变化可以被视为对海洋碳循环的潜在干扰之一。
