Interactions of Au(III) and citrate-stabilized gold nanoparticles (AuNPs) of different nominal diameters (10, 20 and 40 nm) with green microalgae Desmodesmus subspicatus were studied. Both inductively coupled plasma mass spectrometry (ICP MS) and high performance liquid chromatography hyphenated to inductively coupled plasma mass spectrometry (HPLC-ICP MS) were applied to measure total gold content and AuNP size, respectively. After 24 h exposure of algae to gold species at environmentally relevant concentration, quantitative uptake was observed for Au(III), whereas for AuNPs it was size dependent and increased with increasing particle size. It was found that the surface water matrix has no significant influence on the cell-associated amount of gold as the uptake was comparable for algae suspended in Milli-Q and surface water. To characterise the transformations of gold species in aquatic environments, hydrodynamic diameters of AuNPs in surface water, algal cells and supernatants were determined. Gold species were extracted from algal cells using an optimized ultrasound assisted extraction procedure. The accuracy of size determination was evaluated by analysis of NIST Reference Material 8011 (10 nm AuNPs). Cellular localization and core diameter determinations of AuNPs were performed by transmission electron microscopy (TEM). It was found that the introduction of Au(III) into algal cultures leads to intracellular localization of AuNPs (6–7 nm). The 10, 20 and 40 nm AuNPs did not penetrate inside cells; however, their hydrodynamic size increased after the incubation test due to the formation of a biocorona. The thickness of the biomolecule corona was calculated and it depended on particle size. Despite the observed uptake and transformations of gold species, no effect on algal growth was noticed during the 24 h incubation period at the studied exposure concentration.

The aim of the study is an ecotoxicological assessment of magnetite iron oxide-based nanoparticles (NPs), which have risen in popularity in the last decade, on selected terrestrial and aquatic organisms from various levels of the food chain. In the presented study various organisms, from both the terrestrial and aquatic environment, were used as targets for the assessment of NPs ecotoxicity. Plants (radish, oat), marine bacteria (A. fischeri) and crustacean (H. incongruens) were used to represent producers, decomposers, and consumers, respectively. It was found that examined NPs were harmful (to a different degree) to biota from three different trophic levels. Physicochemical characterization (size/morphology, crystallinity, composition, and magnetic properties) of the tested nanoparticles was performed by: transmission electron microscopy, X-ray diffraction, energy dispersive spectroscopy, and Mossbauer spectroscopy, respectively. Phytotoxicity was evaluated according to the OECD 208 Guideline, while acute and chronic toxicity of NPs was conducted using bioassays employing bacteria and crustacea, respectively. The phytotoxicity of all investigated iron oxide-based NPs was dependent on concentration and type of NPs formulation and was measured via biomass, seed germination, root length, shoot height, and content of plant pigments. Increasing the concentration of NPs increased phytotoxicity and mortality of aquatic organisms. Ecotoxicity of iron oxide/silver was dependent on the size and content of silver. Iron oxide NPs coated with nanosilver in a percentage ratio of 69/31 were found to be the most toxic on tested terrestrial and aquatic biota.