Interactions on Cerium oxide nanoparticles with natural biomolecules affect toxicity for aquatic biota

While societal benefits and improvements of nanotechnology are well established, several concerns have raised regarding the potential risk of nanoparticles (NPs) for the environment and human health. In the framework of a need to properly predict environmental implications of NPs, an emerging challenge is to address the complex dynamic of physicochemical and biological processes that drive NPs toxicity once they are released into natural matrices. Therefore the objective of this study was to perform an ecotoxicological evaluation of CeO2NPs with different surface modifications, representative of NPs bio-interaction with molecules naturally occurring in water environment, to identify the role of biomolecule coating on nanoceria toxicity for aquatic organisms. Ad hoc synthesis of CeO2NPs with different coating agents such as Alginate and Chitosan was performed and the NPs were fully characterized. The crustacean Daphnia magna and the bivalve Dreissena polymorpha were used as biological models to test the different ecotoxicity of the CeO2NPs. Several endpoints were evaluated at different level of biological organization such as: the imbalance of the oxidative status by the measurement of some antioxidant enzyme activities, oxidative damage, genotoxicity and behavioral responses. Overall results show that the coating with chitosan increases CeO2NPs stability in exposure media. The different coating influenced also significantly the toxic effects of CeO2NPs in species-specific way. Our findings emphasize that environmental modifications affect significantly the environmental fate and ecotoxicity of NPs.