Fate, behavior and ecotoxicology of silver nanoparticles: interactions with natural organic matter in aquatic systems

• Ano de defesa: 2020
• Autor(a) principal: Watanabe, Cláudia Hitomi [UNESP]
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: eng
• Instituição de defesa: Universidade Estadual Paulista (Unesp)
• Palavras-chave em Português: nanoparticles; toxicity; humic substances; exopolysaccharides; silver
• Link de acesso: http://hdl.handle.net/11449/192324

When introduced in environment, manufactured nanoparticles (NPs) can interact with biotic and abiotic molecules yielding a transformed NP usually coated with these molecules (natural coating). These different forms of the NPs should be considered as new materials because them distinct properties from the released NPs forms. In fact, these in situ transformations of the NPs have relevant impacts on their toxicological effects, having new or additional risks still not studied. This project aims to determine, understand and predict the impact of natural molecules in the transformations and bio-effects of Ag NPs, widely used as antibacterial agents. Despite the growing interest and use of these NPs, the gathered knowledge on their environmental consequences is still scarce, since the large majority of the studies do not consider the effect of the presence of natural coatings around the particles. In fact, most of the studies do not even determine the effects of the presence of manufactured coatings. Generally, NPs manufacturers add ionic or polymeric coatings to improve their mobility and stabilization in terms of size. Although the possible effects of these manufactured coatings in the NPs behavior there is not systematically studied about their impact. This project aims to overcome the current uncertainty about the environmental safety of manufactured coated NPs, and explore the impact of natural molecules on their environmental risk. The project objectives are: i) characterize the manufactured coated Ag NPs in absence and presence of natural molecules including Humic Substances (HS) and Extracellular Polymeric Substances (EPS), ii) determinate the biocompatible and bioadverse effects of the transformed NPs on the algae Raphidocelis subcapitata and the microcrustacean Daphnia similis and iii) evaluate the transfer of the transformed NPs in the food chain alga-microcrustacean. Thus, this project purposes to introduce a standardized and improved evaluation of the ecotoxicology in order to increase the competitiveness and safety of nanostructured products.