How test vessel properties affect the fate of silver nitrate and sterically stabilized silver nanoparticles in two different test designs used for acute tests with Daphnia magna.
The relation between test conditions such as medium composition or pH on silver nanoparticle (AgNP) behavior and its link to toxicity is one of the major topics in nanoecotoxicological research in the last years. In addition, the adaptation of the ecotoxicological standard tests for nanomaterials is intensely discussed to increase comparability and reliability of results. Due to the limitation of test material production volumes and the need for high-throughput screening, miniaturization has been proposed for several test designs. In the present study, the effect of a miniaturization of the acute Daphnia immobilization test on AgNP behavior was investigated. For this purpose, available, adsorbed, and dissolved silver fractions were measured using AgNP and silver nitrate in the following two test designs: a standard test (ST) design and a miniaturized test (MT) design with reduced test volume and less animals. Despite the increase in surface area in relation to the test volume in MT, more AgNP attached to the ST vessel surface, so that in this case, exposure concentrations were significantly lower compared to the MT assessment. Ionic silver concentrations resulting from AgNP dissolution were similar in both test designs. The same was observed for ionic silver concentrations in silver nitrate (AgNO3) treatments, but adsorbed silver was also higher in ST treatments. Assessing the structure-activity relationships revealed that surface properties such as hydrophobicity, potential binding sites, or surface roughness were of higher importance than surface:volume ratios for both test substances.
['Sakka|Yvonne|Y|http://orcid.org/0000-0002-8581-0496', 'Koeser|Jan|J|', 'Filser|Juliane|J|']
D000818:Animals D004396:Coloring Agents D003621:Daphnia D053768:Metal Nanoparticles D015203:Reproducibility of Results D012834:Silver D012835:Silver Nitrate
Stabilizer Silver nanoparticles Adsorption Lipophilicity Surface interaction