The use of nanoparticles has exponentially increased over the last decade. As a consequence, there is an urgent need for assessing the fate and effects of these nanoparticles in the environment. Because of their bactericidal activity, Ag nanoparticles are one of the most widely used nanoparticles. These particles may be used as such but often they are applied in a functionalized form, which means they contain a coating that may facilitate their action. The coating may influence both the fate and the toxicity of the nanoparticles. For metal-based nanoparticles dissolution is considered an important process that leads to the release of toxic ions, which also contribute or even may explain for most of the toxicity of the nanoparticles. For that reason, it is important to consider both the fate and effects of nanoparticles, as toxicity can never be properly understood without insight also into the dissolution behavior of the particles. Since toxicity is determined by the amount taken up in the body, first step in assessing the risk of nanoparticles is determining their bioaccumulation.
This study is part of a bigger project that aims at linking the fate and effects of Ag nanoparticles. The project focuses on assessing the fate and uptake of different types of Ag nanoparticles in different organisms, with emphasis on soil invertebrates, and comparing their bioavailability with that of a free Ag ionic form (AgNO3).
During the internship, toxicokinetics tests will be performed with the potworm Enchytraeus crypticus and/or the springtail Folsomia candida, using different soil types. As a measure of the availability of the nanoparticles in soil, soil extracts and pore water will be collected and analyzed for Ag concentrations by Atomic Absorption Spectrometry. Bioaccumulation tests will take four weeks and consist of a 2-week uptake phase in which the animals are exposed to a certain concentration of the nanoparticles, after which they are transferred to clean soil for a 2-week elimination phase. During both phases, at different time points animals are analyzed for Ag uptake. A first-order one-compartment model will be used to describe the patterns of uptake and elimination of Ag in the test animals. Appropriate statistical tests will be used to compare the toxicokinetics of the different Ag forms and in the different test soils or different test animals.
Supervision and information
Dr. Ir. C.A.M. (Kees) van Gestel (Room H150, W&N building, VU University)