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Lowry G.V.,Carnegie Mellon University | Lowry G.V.,Center for the Environmental Implications of Nanotechnology | Hill R.J.,McGill University | Harper S.,Oregon State University | And 7 more authors.
Environmental Science: Nano | Year: 2016

Nanoparticle zeta-potentials are relatively easy to measure, and have consistently been proposed in guidance documents as a particle property that must be included for complete nanoparticle characterization. There is also an increasing interest in integrating data collected on nanomaterial properties and behavior measured in different systems (e.g. in vitro assays, surface water, soil) to identify the properties controlling nanomaterial fate and effects, to be able to integrate and reuse datasets beyond their original intent, and ultimately to predict behaviors of new nanomaterials based on their measured properties (i.e. read across), including zeta-potential. Several confounding factors pose difficulty in taking, integrating and interpreting this measurement consistently. Zeta-potential is a modeled quantity determined from measurements of the electrophoretic mobility in a suspension, and its value depends on the nanomaterial properties, the solution conditions, and the theoretical model applied. The ability to use zeta-potential as an explanatory variable for measured behaviors in different systems (or potentially to predict specific behaviors) therefore requires robust reporting with relevant meta-data for the measurement conditions and the model used to convert mobility measurements to zeta-potentials. However, there is currently no such standardization for reporting in the nanoEHS literature. The objective of this tutorial review is to familiarize the nanoEHS research community with the zeta-potential concept and the factors that influence its calculated value and interpretation, including the effects of adsorbed macromolecules. We also provide practical guidance on the precision of measurement, interpretation of zeta-potential as an explanatory variable for processes of interest (e.g. toxicity, environmental fate), and provide advice for addressing common challenges associated with making meaningful zeta-potential measurements using commercial instruments. Finally, we provide specific guidance on the parameters that need to be reported with zeta-potential measurements to maximize interpretability and to support scientific synthesis across data sets. © 2016 The Royal Society of Chemistry.

Yin L.,CAS Wuhan Botanical Garden | Yin L.,Center for the Environmental Implications of Nanotechnology | Yin L.,Duke University | Cheng Y.,Center for the Environmental Implications of Nanotechnology | And 12 more authors.
Environmental Science and Technology | Year: 2011

Silver nanoparticles (AgNPs) are increasingly used as antimicrobial additives in consumer products and may have adverse impacts on organisms when they inadvertently enter ecosystems. This study investigated the uptake and toxicity of AgNPs to the common grass, Lolium multiflorum. We found that root and shoot Ag content increased with increasing AgNP exposures. AgNPs inhibited seedling growth. While exposed to 40 mg L -1 GA-coated AgNPs, seedlings failed to develop root hairs, had highly vacuolated and collapsed cortical cells and broken epidermis and rootcap. In contrast, seedlings exposed to identical concentrations of AgNO3 or supernatants of ultracentrifuged AgNP solutions showed no such abnormalities. AgNP toxicity was influenced by total NP surface area with smaller AgNPs (6 nm) more strongly affecting growth than did similar concentrations of larger (25 nm) NPs for a given mass. Cysteine (which binds Ag +) mitigated the effects of AgNO 3 but did not reduce the toxicity of AgNP treatments. X-ray spectro-microscopy documented silver speciation within exposed roots and suggested that silver is oxidized within plant tissues. Collectively, this study suggests that growth inhibition and cell damage can be directly attributed either to the nanoparticles themselves or to the ability of AgNPs to deliver dissolved Ag to critical biotic receptors. © 2011 American Chemical Society.

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