Bren School of Environmental Science and Management, University of California at Santa Barbara , Santa Barbara, California 93106, United States.
Center for Environmental Implications of Nanotechnology, University of California , Santa Barbara, California 93106, United States.
Environ Sci Technol. 2017 Sep 5;51(17):9774-9783. doi: 10.1021/acs.est.7b02523. Epub 2017 Aug 21.
Due to the potential for interactions between crop plants and engineered nanomaterials (ENMs), there is increasing interest in understanding the bioavailability and effects of ENMs released into soil systems. Here, we investigate the influence of root exudates on the fate of ENMs from a thermodynamic perspective. Nano isothermal titration calorimetry was applied to determine thermodynamic parameters for the interaction between nanocopper (nCu) and synthetic root exudate (SRE) and its components (including sugars, organic acids, amino acids, and phenolic acids), as well as Cu and SRE. The measured binding constant (K = 5.645 × 10 M) indicated strong interactions between nCu particles and SRE, as well as with individual organic acids. The interaction between Cu and SRE was stronger (K = 7.181 × 10 M) but varies for the individual SRE components. nCu dissolution in the presence of SRE was the predominant interaction. In addition, SRE resulted in a complex transformation of nCu, where Cu, Cu, and Cu were formed via oxidation and reduction. Plant-nCu exposure experiments indicate that the binding of SRE with nCu and dissolved Cu ions can significantly decrease Cu uptake and bioaccumulation in plants. nITC provides a fundamental thermodynamic understanding of interactions between nCu and plant root exudates, providing an important tool for understanding plant NP-interactions.
由于作物与工程纳米材料（ENMs）之间存在相互作用的可能性，人们越来越关注了解释放到土壤系统中的 ENMs 的生物可利用性和影响。在这里，我们从热力学角度研究了根分泌物对 ENMs 命运的影响。采用纳米等温滴定量热法测定了纳米铜（nCu）与合成根分泌物（SRE）及其成分（包括糖、有机酸、氨基酸和酚酸）以及 Cu 和 SRE 之间相互作用的热力学参数。测量的结合常数（K=5.645×10 M）表明 nCu 颗粒与 SRE 以及与单个有机酸之间存在强烈相互作用。Cu 与 SRE 的相互作用更强（K=7.181×10 M），但对于单个 SRE 成分则有所不同。在 SRE 存在的情况下，nCu 的溶解是主要的相互作用。此外，SRE 导致 nCu 的复杂转化，其中 Cu、Cu 和 Cu 通过氧化和还原形成。植物-nCu 暴露实验表明，SRE 与 nCu 和溶解的 Cu 离子的结合可以显著降低植物对 Cu 的吸收和生物积累。nITC 为 nCu 与植物根分泌物之间的相互作用提供了基本的热力学理解，为理解植物-NP 相互作用提供了重要工具。
