Abstract
Inherent nanomaterial characteristics, composition, surface chemistry, and primary particle size, are known to impact particle stability, uptake, and toxicity. Nanocomposites challenge our ability to predict nanoparticle reactivity in biological systems if they are composed of materials with contrasting relative toxicities. We hypothesized that toxicity would be dominated by the nanoparticle surface (shell vs core), and that modulating the surface ligands would have a direct impact on uptake. We exposed developing zebrafish (Danio rerio) to a series of ~70 nm amine-terminated silver nanoparticles with silica shells (AgSi NPs) to investigate the relative influence of surface amination, composition, and size on toxicity. Like-sized aminated AgSi and Si NPs were more toxic than paired hydroxyl-terminated nanoparticles; however, both AgSi NPs were more toxic than the Si NPs, indicating a significant contribution of the silver core to the toxicity. Incremental increases in surface amination did not linearly increase uptake and toxicity, but did have a marked impact on dispersion stability. Mass-based exposure metrics initially supported the hypothesis that smaller nanoparticles (20 nm) would be more toxic than larger particles (70 nm). However, surface area-based metrics revealed that toxicity was independent of size. Our studies suggest that nanoparticle surfaces play a critical role in the uptake and toxicity of AgSi NPs, while the impact of size may be a function of the exposure metric used. Overall, uptake and toxicity can be dramatically altered by small changes in surface functionalization or exposure media. Only after understanding the magnitude of these changes, can we begin to understand the biologically available dose following nanoparticle exposure.Electronic supplementary materialThe online version of this article (doi:10.1007/s11051-014-2761-z) contains supplementary material, which is available to authorized users.
Highlights
The rapid growth of the nanotechnology field will likely result in increased human exposure through both commercial goods and the environment
Our studies suggest that nanoparticle surfaces play a critical role in the uptake and toxicity of AgSi NPs, while the impact of size may be a function of the exposure metric used
Nanoparticle tracking analysis (NTA) data largely supported the size data observed with Malvern hydrodynamic sizes, except for the 20 nm AgSi NPs, which recorded a smaller hydrodynamic diameter (HDD) for nm 19 AgSi NPs (Online Resource 2C)
Summary
The rapid growth of the nanotechnology field will likely result in increased human exposure through both commercial goods and the environment. As the field advances, more complex composite nanomaterials are emerging in attempts to achieve applicationdriven needs in healthcare, environmental engineering, and material sciences (Tian et al 2014; Zhi et al 2013). Such alterations to bare nanoparticles may have dramatic impacts on their reactivity, stability, uptake, and toxicity (Kasturirangan et al 2013; Rossi et al 2010; Sotiriou et al 2011). Predicting the potential uptake and toxicity of nanocomposites presents a new challenge of whether or not conclusions can be drawn from toxicity studies of single-composition nanoparticle exposures and accurately forecast the potential toxicity of next-generation nanoparticles
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