School of Environment, Key Laboratory for Yellow River and Huai River Water Environment and Pollution Control, Ministry of Education, Henan Key Laboratory for Environmental Pollution Control, International Joint Laboratory on Key Techniques in Water Treatment, Henan Normal University, Xinxiang 453007, China.
Key Laboratory of Pollution Processes and Environmental Criteria (Ministry of Education)/Tianjin Key Laboratory of Environmental Remediation and Pollution Control, College of Environmental Science and Engineering, Nankai University, Tianjin 300350, China.
Environ Sci Technol. 2022 Jul 5;56(13):9556-9568. doi: 10.1021/acs.est.1c08534. Epub 2022 May 16.
Thorough investigations of the environmental fate and risks are necessary for the safe application of engineered nanomaterials. Nevertheless, the current understanding of potential transformations of MoS (an intensively studied two-dimensional nanosheet) upon interactions with ubiquitous environmentally relevant thiols (ERTs) in water is limited. This study revealed that two ERTs, l-cysteine and mercaptoacetic acid, could modify MoS by covalently grafting thiol groups on S atoms of 1T phases, improving the colloidal persistence and chemical stability of MoS. Compared with the pristine form, MoS-thiols with higher dispersity exhibited significantly mitigated envelopment and ultrastructural damage to microalgae. MoS-triggered growth inhibition, upregulation of reactive oxygen species, photosynthetic injury, and metabolic perturbation in algae were remarkably attenuated by ERTs. The diminished capability for MoS to generate reactive intermediates and glutathione oxidation driven by ERTs caused the weakness of oxidative stress and negative effects. Additionally, molecular dynamics simulations demonstrated that ERTs altered the extent of the influence of MoS on the secondary structures and functions of adsorbed intracellular proteins, which also contributed to the lower phytotoxicity of MoS. Our findings provide evidence for the crucial role of specific organic ligands in the risk of MoS in aquatic environments.
深入研究工程纳米材料的环境归宿和风险对于其安全应用是必要的。然而，目前对于普遍存在的环境相关硫醇（ERTs）与 MoS（一种被广泛研究的二维纳米片）相互作用时潜在转化的理解是有限的。本研究表明，两种 ERTs，半胱氨酸和巯基乙酸，可以通过将硫醇基团共价接枝到 1T 相的 S 原子上来修饰 MoS，从而提高 MoS 的胶体稳定性和化学稳定性。与原始形式相比，具有更高分散性的 MoS-硫醇对微藻的包裹和超微结构损伤有明显减轻。ERTs 显著减弱了 MoS 对藻类的生长抑制、活性氧的上调、光合作用损伤和代谢扰动。ERTs 降低了 MoS 产生反应中间体和谷胱甘肽氧化的能力，导致氧化应激和负面效应减弱。此外，分子动力学模拟表明，ERTs 改变了 MoS 对吸附细胞内蛋白质二级结构和功能影响的程度，这也导致 MoS 的植物毒性降低。我们的研究结果为特定有机配体在 MoS 水生环境风险中的关键作用提供了证据。
