This work investigates the effect of chloride ion (Cl^–) on dissolution, reactive oxygen species (ROS) generation, and toxicity of citrate-coated silver nanoparticles (AgNPs) under UV irradiation. The dissolution rate was decreased by 0.01 M Cl^– due to AgCl passivation on the AgNP surface. By contrast, high concentrations of Cl^– (0.1 or 0.5 M) promoted dissolution due to the formation of soluble Ag–Cl complexes (AgCl_x^1–x). The generation of O₂^•– in the AgNPs/Cl^–/UV system was promoted by 0.01 M Cl^–, whereas it was retarded by 0.1 or 0.5 M Cl^–, which was probably because the aggregation of AgNPs at high ionic strength reduced the nanoparticles’ surface areas for radical formation. Additionally, Cl^– contributed to •OH generation in the AgNPs/Cl^–/UV system, in which the produced •OH concentrations increased with increasing Cl^– concentrations. The reduction reaction between silver ions and O₂^•– resulted in lower dissolution rates of AgNPs/Cl^– mixtures under UV irradiation than those in the dark. The phototoxicity of AgNPs toward E. coli with different concentrations of Cl^– followed the order of 0.5 M > 0 M > 0.1 M > 0.01 M. Both ROS and dissolved Ag played significant role in the phototoxicity of AgNPs. This work demonstrates the potential importance of anions in the fate and biological impact of AgNPs.

中文翻译：

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氯离子对紫外线辐照下银纳米粒子的溶解，ROS生成和毒性的影响

这项工作调查氯离子的作用（CL ^- ）对溶出，活性氧（ROS）的产生，和柠檬酸盐涂覆的银纳米颗粒（的AgNPs）毒性UV辐射下。由于AgNP表面上的AgCl钝化，溶解速率降低了0.01 M Cl ^–。相比之下，高浓度的Cl ^–（0.1或0.5 M）由于可溶性Ag–Cl络合物（AgCl _x ^{1– x}）的形成而促进了溶解。0.01 M Cl ^–促进了AgNPs / Cl ^– / UV系统中O ₂ ^•–的生成，而0.1或0.5 M Cl ^–则阻止了O ₂ ^•–的生成。，这可能是因为高离子强度的AgNP的聚集减少了纳米颗粒形成自由基的表面积。此外，氯^-促成•OH产生在的AgNPs /氯^- / UV系统，其中所产生的•OH浓度随增加氯^-浓度。银离子和O ₂ ^•–之间的还原反应导致紫外线下的AgNPs / Cl ^–混合物的溶解速率低于黑暗中的AgNPs / Cl ^–混合物的溶解速率。AgNPs对不同浓度Cl ^–的大肠杆菌的光毒性遵循0.5 M> 0 M> 0.1 M> 0.01 M的顺序。ROS和溶解的Ag在AgNPs的光毒性中均起着重要作用。这项工作证明了阴离子对AgNPs的命运和生物学影响的潜在重要性。