College of Environmental Science and Engineering, Hunan University and Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha, 410082, PR China.
Department of Dermatology, Second Xiangya Hospital, Central South University, Changsha, 410011, PR China.
Chemosphere. 2018 Jul;203:199-208. doi: 10.1016/j.chemosphere.2018.03.144. Epub 2018 Mar 21.
Potential transformations of silver nanoparticles (AgNPs) upon interaction with naturally ubiquitous organic ligands in aquatic environments influence their transport, persistence, bioavailability, and subsequent toxicity to organisms. In this study, differential behaviors of AgNPs and silver ions (Ag) towards cysteine (Cys), an amino acid representative of thiol ligands that easily coordinate to Ag and graft to nanoparticle surfaces, were investigated in the aspects of bioremediation and their toxicity to Phanerochaete chrysosporium. Total Ag removal, 2,4-dichlorophenol (2,4-DCP) degradation, extracellular protein secretion, and cellular viability were enhanced to some extent after supplement of various concentrations of cysteine under stress of AgNPs and Ag. However, an obvious decrease in total Ag uptake was observed after 5-50 μM cysteine addition in the groups treated with 10 μM AgNPs and 1 μM Ag, especially at a Cys:Ag molar ratio of 5. More stabilization in uptake pattern at this ratio was detected under Ag exposure than that under AgNP exposure. Furthermore, in the absence of cysteine, all Ag treatments stimulated the generation of reactive oxygen species (ROS) more significantly than high-dose AgNPs did. However, cysteine supply under AgNP/Ag stress aggravated ROS levels, albeit alleviated at 100 μM Ag, indicating that the toxicity profiles of AgNPs and Ag to P. chrysosporium could be exacerbated or marginally mitigated by cysteine. The results obtained were possibly associated with the lability and bioavailability of AgNP/Ag-cysteine complexes.
在水环境中，与天然普遍存在的有机配体相互作用的银纳米粒子（AgNPs）的潜在转化会影响它们的传输、持久性、生物利用度以及对生物体的后续毒性。在这项研究中，我们研究了 AgNPs 和银离子（Ag）与半胱氨酸（Cys）的不同行为，Cys 是一种代表容易与 Ag 配位并接枝到纳米粒子表面的巯基配体的氨基酸。在银纳米粒子和银的胁迫下，半胱氨酸在生物修复和对黄孢原毛平革菌的毒性方面的不同浓度对总银去除、2,4-二氯苯酚（2,4-DCP）降解、细胞外蛋白分泌和细胞活力都有不同程度的增强。然而，在添加 10 μM AgNPs 和 1 μM Ag 的组中，在添加 5-50 μM 半胱氨酸后，总银摄取量明显下降，特别是在 Cys:Ag 摩尔比为 5 时。在 Ag 暴露下比在 AgNP 暴露下检测到更高的在该比例下吸收模式的稳定性。此外，在没有半胱氨酸的情况下，所有 Ag 处理比高剂量 AgNPs 更显著地刺激活性氧物质（ROS）的产生。然而，在 AgNP/Ag 胁迫下提供半胱氨酸会加重 ROS 水平，尽管在 100 μM Ag 时会有所缓解，这表明 AgNPs 和 Ag 对黄孢原毛平革菌的毒性特征可能会因半胱氨酸的存在而加剧或略微减轻。所得结果可能与 AgNP/Ag-半胱氨酸复合物的不稳定性和生物利用度有关。
