Abstract
The expected potential benefits promised by nanotechnology in various fields have led to a rapid increase of the presence of engineered nanomaterials in a high number of commercial goods. This is generating increasing questions about possible risks for human health and environment, due to the lack of an in-depth assessment of the physical/chemical factors responsible for their toxic effects. In this work, we evaluated the toxicity of monodisperse citrate-capped gold nanoparticles (AuNPs) of different sizes (5, 15, 40, and 80 nm) in the model organism Drosophila melanogaster, upon ingestion. To properly evaluate and distinguish the possible dose- and/or size-dependent toxicity of the AuNPs, we performed a thorough assessment of their biological effects, using two different dose-metrics. In the first approach, we kept constant the total surface area of the differently sized AuNPs (Total Exposed Surface area approach, TES), while, in the second approach, we used the same number concentration of the four different sizes of AuNPs (Total Number of Nanoparticles approach, TNN). We observed a significant AuNPs-induced toxicity in vivo, namely a strong reduction of Drosophila lifespan and fertility performance, presence of DNA fragmentation, as well as a significant modification in the expression levels of genes involved in stress responses, DNA damage recognition and apoptosis pathway. Interestingly, we found that, within the investigated experimental conditions, the toxic effects in the exposed organisms were directly related to the concentration of the AuNPs administered, irrespective of their size.
Highlights
The rapid expansion of nanotechnology is producing a huge assortment of nanoparticles that differ in chemical composition, size, shape, surface charge and chemistry, coating and dispersion status [1]
In this work we investigated the in vivo effects of metrologically controlled gold nanoparticles (AuNPs) of different size (5, 15, 40 and 80 nm, with a size dispersion #6%) on the model organism Drosophila melanogaster, upon ingestion
In this study we used two experimental approaches (TES and TNN) to evaluate the toxic effects of differently sized (5, 15, 40, and 80 nm) and monodispersed citrate-capped AuNPs in Drosophila melanogaster upon ingestion
Summary
The rapid expansion of nanotechnology is producing a huge assortment of nanoparticles that differ in chemical composition, size, shape, surface charge and chemistry, coating and dispersion status [1]. Several studies have demonstrated the existence of biophysicochemical interactions at the nano–bio interface, such as protein corona formation, which may have a significant role in the intracellular uptake of nanomaterials, with possible influences on the toxicity outcomes [6,7,8] All these issues generally make the comparison of the experimental results from different nanotoxicological studies rather difficult [9,10]. In this context, it is important to define a rigorous strategy to study the complex interactions occurring between nanostructured materials and living systems, by a deep nanomaterial characterization followed by a well established in vivo experimental procedure. This approach may be useful to define a correct experimental route [11,12] that may provide a deeper understanding in the definition of dose, dose metrics, and biokinetics in the case of NPs
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