TiO2 nanoparticles' library toxicity (UV and non-UV exposure) – High-throughput in vivo transcriptomics reveals mechanisms. Enchytraeus crypticus

Ecotoxicological studies with NPs are nearly all focused on testing one or few NPs. A more systematic approach to compare effects across many NMs with identified different but related characters/descriptors (e.g. different aspect-ratios or surface activities) are only sparsely reported especially in ecotoxicology. There is an urgent need to provide tools that allow us to fast develop an (eco)toxicological dataset containing comprehensive toxicity information relating to a diverse spectra of NPs characters, thus allowing the extrapolation of acquired information across NMs. NM libraries are an excellent tool for alternative testing and modeling. In the present study a custom-designed Fe doped TiO2 NM library was used covering of a wide spectrum of properties. Enchytraeus crypticus (Oligochateta) was used as test species since it is both environmentally relevant (as an important soil representative oligochaete and is also a standard species in soil ecotoxicology studies) and also a genomic model, with a high-throughput (HTP) genomic library. Effects were assessed at the organism (survival, reproduction) and gene level (differential gene expression, microarray). Overall design: Gene expression profile of Enchytraeus crypticus was analysed after 5 days of exposure to: i) TiO2 NMs under standard lab illumination (No-UV) and ii) TiO2 NMs + UV radiation. To maximise exposure, the test media was reconstituted water (ISO 1). The treatments selected (concentration/NM) were based on previous known effects on reproduction (3 weeks) after transference to clean LUFA 2.2 soil; and the treatments were selected to cover a wide range of NM characteristics and different effects. Three biological replicates per test treatment and controls (standard laboratory light or UV) were used.