Biophysical Environmental Chemistry Group Department of Chemistry, University of Montreal , C.P. 6128 Succursale Centre-ville, Montreal H3C 3J7, Canada.
Environ Sci Technol. 2014;48(1):358-64. doi: 10.1021/es404037z. Epub 2013 Dec 13.
The bioavailability of a small silver nanoparticle (nAg; nominal size of 5 nm with a polyacrylate coating) by the green alga C. reinhardtii was investigated in order to assess the contributions of Ag(+) and nAg to cellular internalization. Upon exposure to nAg, Ag biouptake exceeded what was predicted based upon measured Ag(+) concentrations. Indeed, although Ag biouptake was greatly reduced when excess cysteine was added to the nAg, it was nonetheless significantly above control levels. For both exposures to nAg and Ag(+), expression levels of the Copper Transport Protein 2 (CTR2) indicated that Ag biouptake could be attributed to the internalization of Ag(+). Exposure to Ag(+) or nAg increased CTR2 expression, even when cysteine was present with the nAg. Darkfield microscopy coupled with hyperspectral imagery showed that the presence of silver nanoparticles inside the cells was more likely due to the rereduction of Ag(+) than to the internalization of nAg. The weight of evidence indicated that nAg increased Ag biouptake by locally increasing the surface concentrations of Ag(+).
为了评估 Ag(+) 和 nAg（粒径为 5nm 且具有聚丙烯酸酯涂层的纳米银）对细胞内化的贡献，研究了小银纳米颗粒（nAg）在绿藻 C. reinhardtii 中的生物利用度。暴露于 nAg 后，Ag 的生物摄取量超过了根据测量的 Ag(+)浓度预测的值。事实上，尽管当向 nAg 中添加过量半胱氨酸时，Ag 的生物摄取量大大降低，但它仍然显著高于对照水平。对于 nAg 和 Ag(+) 的两种暴露，铜转运蛋白 2（CTR2）的表达水平表明，Ag 的生物摄取可以归因于 Ag(+)的内化。即使在 nAg 中存在半胱氨酸，Ag(+)或 nAg 的暴露也会增加 CTR2 的表达。暗场显微镜结合高光谱成像表明，银纳米颗粒在细胞内的存在更可能是由于 Ag(+)的再还原，而不是 nAg 的内化。大量证据表明，nAg 通过局部增加 Ag(+)的表面浓度来增加 Ag 的生物摄取量。
