Ecotoxicological effects of a “smart” engineered nanomaterial in zebrafish

• Autor(a) principal: Carneiro, Diana Isabel Oliveira
• Data de Publicação: 2021
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10773/30959
• topic: Layered double hydroxides; DNA damage; Hazard assessment; Danio rerio

Layered Double Hydroxides (LDH) are anionic nanoclays, composed of positively-charged layers with divalent or trivalent metal cations (e.g., Zn2+ or Al3+) and stabilized by anions (e.g., nitrates) and water molecules in the interlayers. LDHs have remarkable properties namely excellent anion exchangeability, memory effect, biocompatibility, pH sensitivity, high surface to volume ratio, and high adsorbing capacity. LDHs have been regarded as “smart” engineered nanomaterials and lately received great interest in multiple areas, such as medicine, pharmaceutical, industry, among others. These nanomaterials are of low toxicity to humans, mammals, and marine organisms. However, ecotoxicological effects on freshwater organisms are scarcely studied, which is critical for regulatory purposes. The zebrafish Danio rerio is a wellestablished freshwater model organism that is widely used in toxicological and ecotoxicological assessment of innumerous contaminants. Several studies are using the zebrafish to evaluate the toxicity of nanomaterials, mainly metallic nanoparticles. The present study aimed to assess the ecotoxicological effects of Zn-Al LDH in Danio rerio. Danio rerio eggs were exposed to Zn-Al LDHs to assess developmental, behavioural, biochemical, and molecular (at the DNA level) changes. For the evaluation of embryotoxicity, the eggs were exposed to Zn-Al LDH (85 - 1200 mg/L) according to the OECD 236 protocol, where mortality, malformations, and hatching success were recorded daily for 96 hours. In the behavioural test, the embryos were exposed to sublethal concentrations of Zn-Al LDH (9 - 94 mg/L) for 120 h. The evaluation of genotoxicity (comet assay) and biomarkers of neurotoxicity and oxidative stress after a 96 h exposure of eggs to nanomaterial (9 - 94 mg/L). The behaviour and fate of LDHs in the water of the zebrafish system were characterized through the zeta potential and hydrodynamic particle size.