Key Laboratory of Pollution Processes and Environmental Criteria (Ministry of Education)/Carbon Neutrality Science Center, College of Environmental Science and Engineering, Nankai University, Tianjin 300350, China.
Key Laboratory of Pollution Processes and Environmental Criteria (Ministry of Education)/Carbon Neutrality Science Center, College of Environmental Science and Engineering, Nankai University, Tianjin 300350, China.
Water Res. 2024 Aug 15;260:121908. doi: 10.1016/j.watres.2024.121908. Epub 2024 Jun 8.
Graphene oxide (GO, a popular 2D nanomaterial) poses great potential in water treatment arousing considerable attention regarding its fate and risk in aquatic environments. Extracellular polymeric substances (EPS) exist widely in water and play critical roles in biogeochemical processes. However, the influences of complex EPS fractions on the fate and risk of GO remain unknown in water. This study integrates fluorescence excitation-emission matrix-parallel factor, two-dimensional correlation spectroscopy, and biolayer interferometry studies on the binding characteristics and affinity between EPS fractions and GO. The results revealed the preferential binding of fluorescent aromatic protein-like component, fulvic-like component, and non-fluorescent polysaccharide in soluble EPS (S-EPS) and bound EPS (B-EPS) on GO via π-π stacking and electrostatic interaction that contributed to a higher adsorption capacity of S-EPS on GO and weaker affinity than of B-EPS. Moreover, the EPS fractions drive the morphological and structural alterations, and the attenuated colloid stability of GO in water. Notably, GO-EPS induced stronger phytotoxicity (e.g., photosynthetic damage, and membrane lipid remodeling) compared to pristine GO. Metabolic and functional lipid analysis further elucidated the regulation of amino acid, carbohydrate, and lipid metabolism contributed to the persistent phytotoxicity. This work provides insights into the roles and mechanisms of EPS fractions composition in regulating the environmental fate and risk of GO in natural water.
氧化石墨烯（GO，一种流行的二维纳米材料）在水处理方面具有巨大的潜力，由于其在水生环境中的归宿和风险引起了相当大的关注。细胞外聚合物（EPS）广泛存在于水中，在生物地球化学过程中发挥着关键作用。然而，复杂的 EPS 组分对 GO 在水中的归宿和风险的影响仍不清楚。本研究通过荧光激发-发射矩阵-平行因子、二维相关光谱和生物层干涉研究，结合了对 EPS 组分与 GO 之间结合特性和亲和力的研究。结果表明，通过 π-π 堆积和静电相互作用，可溶性 EPS（S-EPS）和结合 EPS（B-EPS）中的荧光芳香蛋白样组分、富里酸样组分和非荧光多糖优先结合到 GO 上，这导致 S-EPS 在 GO 上的吸附容量更高，而与 B-EPS 的亲和力较弱。此外，EPS 组分驱动 GO 在水中的形态和结构改变，以及胶体稳定性减弱。值得注意的是，GO-EPS 比原始 GO 引起更强的植物毒性（例如光合作用损伤和膜脂重塑）。代谢和功能脂质分析进一步阐明了氨基酸、碳水化合物和脂质代谢的调节作用，导致持续的植物毒性。这项工作深入了解了 EPS 组分组成在调节 GO 在自然水中的环境归宿和风险方面的作用和机制。
