Silica coating prevents magnetic nanoparticles toxicity: a morphological and molecular study in Zebrafish

Nanoparticles (NPs) are novel man-made materials on the nanoscale. A wide range of nanomaterials is being developed for technical applications and for use in consumer products. Metal NPs, including superparamagnetic iron oxide NPs [magnetite (Fe3O4) and maghemite (γ-Fe2O3)], are interesting tools that can be used in a wide range of biomedical applications. Researches are still in progress and reports about the toxicity of iron oxide NPs are often contradictory. Recent studies carried out in fish, have described different sublethal effects ranging from respiratory toxicity, to oxidative stress involving gill, liver, and gut function and morphology (Li et al. 2009). Moreover, several investigations have found that early life stages, such as embryos and larvae, are more sensitive to NPs than adult forms. The main route of NPs exposure for fish is through the food and the food web and NPs biomagnification, bioaccumulation and bioconcentration phenomena have also been described. NPs encapsulation procedures in a robust shell made of gold, silica, zinc oxide, a polymer, or liposomes not only protects the magnetic core from chemical reactions but also prevents interactions with sensitive biological media. In particular, the silica coating provides stable and multifunctional NPs. Considering that datasets on this topic are still limited and that the effects of dietary exposure to silica-coated magnetic NPs have never been studied so far, this study, explores for the first time silica-coated magnetic NPs direct action on zebrafish (ZF) larvae fed NP-contaminated food and longer-term effects on adults. A multidisciplinary approach, including morphometric examination (light, transmission electron, and confocal microscopy), inductively coupled plasma emission spectrometry and real-time PCRs was applied to detect NPs accumulation, structural and ultrastructural damage, and activation of detoxification processes in larvae and adults.