Nano-silver induces dose-response effects on the nematode Caenorhabditis elegans

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• 作者：Lea Ellegaard-Jensen^a ; ^c ; Keld Alstrup Jensen^b ; Anders Johansen^c ; ^ajo@dmu.dk
• 关键词：Dose-response ; Nano-silver ; Nematode ; Caenorhabditis elegans ; Nanoparticle
• 刊名：Ecotoxicology and Environmental Safety
• 出版年：2012
• 期刊代码：77_01476513
• 类别：env
• 出版时间：1 June, 2012
• 卷：80
• 期：Complete
• 页码：216-223
• 文件大小：569 K

摘要

Toxicity of nano-formulated silver to eukaryotes was assessed by exposing nematodes (Caenorhabditis elegans) to two types of silver nanoparticles (AgNPs): with average primary particle diameters of 1 nm (AgNP1) and 28 nm (AgNP28, PVP coated), respectively. Tests were performed with and without presence of Escherichia coli to evaluate how the presence of a food bacterium affects the AgNP toxicity. A pre-exposure experiment was also conducted with nematodes pre-exposed to 0 and 1 mg AgNP L^鈭?, respectively, for 20 h prior to exposure at higher concentrations of AgNP. Both AgNP1 and AgNP28 showed adverse dose-response effects and mortality on C. elegans. LC₅₀ for AgNP28 was lower than for AgNP1 and, hence, at the present test conditions the PVP-coated AgNP28 was more toxic than AgNP1. Including E. coli in the test medium as a food source increased AgNPs toxicity towards nematodes compared to when bacteria were not present. Pre-exposure to a low-level AgNP1 concentration made the nematodes slightly more sensitive to further exposure at higher concentrations compared to no pre-exposure, indicating that nematodes have no efficient physiological ability to counteract nano-silver toxicity by acclimation. The amount of dissolved Ag⁺ was 0.18 to 0.21 mg L^鈭? after 20 h at the highest AgNP1 (10 mg L^鈭?) and AgNP28 (3 mg L^鈭?) doses in the exposure medium, respectively. The upper limit of Ag⁺ solubility cannot immediately explain the dose-response-related toxic effects of the AgNP nor the difference between AgNP1 and AgNP28. Higher toxicity of AgNP28 than AgNP1 may be explained by a combination of effects of coating, Ag-solubility and higher uptake rates due to agglomeration into 渭m-size agglomerates in the exposure medium.