Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada.
Environ Sci Technol. 2012 Sep 18;46(18):10295-301. doi: 10.1021/es3017717. Epub 2012 Sep 4.
The silver ion (Ag(+)) is well documented to be a potent inhibitor of sodium (Na(+)) transport in fish. However, it has not been determined whether silver nanoparticles (Ag NPs) elicit this same effect and, if so, if the NP itself and/or the dissociation of ionic Ag(+) causes this effect. Citrate-capped Ag NPs were dialyzed in water to determine the dissolution rate of ionic Ag(+) from the NPs and the maximum concentration of free Ag(+) released from the NPs was used as a paired Ag(+) control to distinguish NP effects from ionic metal effects. The maximum concentration of ionic Ag(+) released from these NPs over 48 h was 0.02 μg l(-1). Juvenile rainbow trout were exposed to 1.0 mg l(-1) citrate-capped Ag NPs and dialyzed citrate-capped Ag NPs or 10 μg l(-1) and 0.02 μg l(-1) ionic Ag(+) (as AgNO(3)) as controls. Both nondialyzed and dialyzed Ag NPs and 10 μg l(-1) ionic Ag(+) significantly inhibited unidirectional Na(+) influx by over 50% but had no effect on unidirectional Na(+) efflux. Na(+),K(+)-ATPase was significantly inhibited by the Ag NPs with no discernible effect on carbonic anhydrase activity. This study is the first to show that sodium regulation is disrupted by the presence of citrate-capped Ag NPs, and the results suggest that there are nanospecific effects.
银离子（Ag(+)）被充分证明是鱼类钠离子（Na(+)）转运的有效抑制剂。然而，目前尚不清楚纳米银颗粒（Ag NPs）是否会产生同样的效果，如果是这样，是否是 NP 本身和/或离子 Ag(+)的解离导致了这种效果。用柠檬酸根封端的 Ag NPs 进行水透析，以确定 NP 中离子 Ag(+)的溶解速率，并用 NP 释放的最大游离 Ag(+)浓度作为配对的 Ag(+)对照，以区分 NP 效应和离子金属效应。这些 NP 在 48 小时内释放的最大离子 Ag(+)浓度为 0.02 μg l(-1)。将幼虹鳟暴露于 1.0 mg l(-1)柠檬酸根封端的 Ag NPs 和透析过的柠檬酸根封端的 Ag NPs 或 10 μg l(-1)和 0.02 μg l(-1)离子 Ag(+)（以 AgNO(3)形式存在）作为对照。未透析和透析的 Ag NPs 以及 10 μg l(-1)离子 Ag(+)均显著抑制了单向 Na(+)内流超过 50%，但对单向 Na(+)外排没有影响。Ag NPs 显著抑制了 Na(+)，K(+)-ATPase，而对碳酸酐酶活性没有明显影响。这项研究首次表明，柠檬酸根封端的 Ag NPs 的存在会破坏钠的调节，结果表明存在纳米特异性效应。
