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

TY - JOUR

T1 - Nano-silver induces dose-response effects on the nematode Caenorhabditis elegans

AU - Ellegaard-Jensen, Lea

AU - Jensen, Keld Alstrup

AU - Johansen, Anders

PY - 2012/6/1

Y1 - 2012/6/1

N2 - 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 1nm (AgNP1) and 28nm (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 1mgAgNPL -1, respectively, for 20h prior to exposure at higher concentrations of AgNP. Both AgNP1 and AgNP28 showed adverse dose-response effects and mortality on C. elegans. LC 50 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 0.21mgL -1 after 20h at the highest AgNP1 (10mgL -1) and AgNP28 (3mgL -1) 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 μm-size agglomerates in the exposure medium.

AB - 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 1nm (AgNP1) and 28nm (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 1mgAgNPL -1, respectively, for 20h prior to exposure at higher concentrations of AgNP. Both AgNP1 and AgNP28 showed adverse dose-response effects and mortality on C. elegans. LC 50 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 0.21mgL -1 after 20h at the highest AgNP1 (10mgL -1) and AgNP28 (3mgL -1) 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 μm-size agglomerates in the exposure medium.

U2 - 10.1016/j.ecoenv.2012.03.003

DO - 10.1016/j.ecoenv.2012.03.003

M3 - Journal article

C2 - 22475389

SN - 0147-6513

VL - 80

SP - 216

EP - 223

JO - Ecotoxicology and Environmental Safety

JF - Ecotoxicology and Environmental Safety

ER -