Although the toxic effects of two-dimensional nanomaterials (2D-NMs) have been widely reported, the influence of extracellular polymeric substances (EPS) on the environmental fate and risk of 2D-NMs in aquatic environments is largely unknown, and the processes and mechanisms involved remain to be revealed. Herein, we investigated the impact of EPS secreted by microalgae (Chlorella vulgaris (C. vulgaris)) on the environmental transformation and risk of molybdenum disulfide (MoS₂). We found that the attachment of EPS increased the thickness of MoS₂ (from 2 nm to 5 nm), changed it from a monolayer sheet to a fuzzy multilayer structure, and promoted the formation of defects on MoS₂. The blue-shift of the peak associated with the plasmon resonances in the 1 T phase and the generation of electron-hole pairs suggested that EPS altered the surface electronic structure of MoS₂. EPS interacted mainly with the S atoms on the 1 T phase, and the attachment of EPS promoted the oxidation of MoS₂. The reduction in hydrodynamic diameter (D_h) and the decrease in zeta potential indicated that EPS inhibited the agglomeration behavior of MoS₂ and enhanced its dispersion and stability in aqueous media. Notably, EPS reduced the generation of free radicals (superoxide anion (•O₂⁻), singlet oxygen (¹O₂), and hydroxyl radicals (•OH⁻)). Furthermore, EPS mitigated the toxicity of MoS₂ to C. vulgaris, such as attenuated reduction in biomass and chlorophyll content. Compared to pristine MoS₂, MoS₂ + BG11 + EPS exhibited weaker oxidative stress, membrane damage and lipid peroxidation. The adsorption of EPS on MoS₂ surface reduced the attachment sites of MoS₂, making MoS₂ less likely to be enriched on the cell surface. The findings have significant contribution for understanding the interactions between EPS and MoS₂ in aquatic ecosystems, providing scientific guidance for risk assessment of 2D-NMs.

尽管二维纳米材料（2D-NMs）的毒性作用已被广泛报道，但细胞外聚合物（EPS）对水生环境中2D-NMs的环境命运和风险的影响很大程度上未知，其过程和机制涉及的内容还有待揭晓。在此，我们研究了微藻（小球藻（C. vulgaris））分泌的EPS对二硫化钼（MoS ₂ ）环境转化和风险的影响。_{我们发现EPS的附着增加了MoS 2}的厚度（从2 nm到5 nm），将其从单层片状结构转变为模糊的多层结构，并促进了MoS 2 上缺陷的_形成。与 1 T 相中的等离激元共振相关的峰蓝移和电子空穴对的产生表明 EPS 改变了 MoS 2 的表面电子_结构。EPS主要与1 T相上的S原子相互作用，EPS的附着促进了MoS ₂的氧化。流体动力学直径( D _{h )的减小和zeta电位的降低表明EPS抑制了MoS 2}的团聚行为并增强了其在水介质中的分散性和稳定性。_{值得注意的是，EPS 减少了自由基（超氧阴离子 (•O 2} ^- )、单线态氧 ( ¹ O ₂ ) 和羟基自由基 (•OH ^- )）的产生。_{此外，EPS减轻了MoS 2}对普通念珠菌的毒性，例如减弱了生物量和叶绿素含量的降低。与原始MoS ₂相比，MoS ₂  + BG11 + EPS 表现出较弱的氧化应激、膜损伤和脂质过氧化。EPS在MoS _{2表面的吸附减少了MoS 2}的附着位点，使得MoS ₂不太可能在细胞表面富集。该研究结果对于理解水生生态系统中EPS和MoS ₂之间的相互作用具有重要贡献，为2D-NMs的风险评估提供科学指导。