Demonstrating approaches to chemically modify the surface of Ag nanoparticles in order to influence their cytotoxicity and biodistribution after single dose acute intravenous administration

With the advance in material science and the need to diversify market applications, silver nanoparticles (AgNPs) are modified by different surface coatings. However, how these surface modifications influence the effects of AgNPs on human health is still largely unknown. We have evaluated the uptake, toxicity and pharmacokinetics of AgNPs coated with citrate, polyethylene glycol, polyvinyl pyrolidone and branched polyethyleneimine (Citrate AgNPs, PEG AgNPs, PVP AgNPs and BPEI AgNPs, respectively). Our results demonstrated that the toxicity of AgNPs depends on the intracellular localization that was highly dependent on the surface charge. BPEI AgNPs ( potential=+46.5mV) induced the highest cytotoxicity and DNA fragmentation in Hepa1c1c7. In addition, it showed the highest damage to the nucleus of liver cells in the exposed mice, which is associated with a high accumulation in liver tissues. The PEG AgNPs ( potential=-16.2mV) showed the cytotoxicity, a long blood circulation, as well as bioaccumulation in spleen (34.33 mu g/g), which suggest better biocompatibility compared to the other chemically modified AgNPs. Moreover, the adsorption ability with bovine serum albumin revealed that the PEG surface of AgNPs has an optimal biological inertia and can effectively resist opsonization or non-specific binding to protein in mice. The overall results indicated that the biodistribution of AgNPs was significantly dependent on surface chemistry: BPEI AgNPs>Citrate AgNPs=PVP AgNPs>PEG AgNPs. This toxicological data could be useful in supporting the development of safe AgNPs for consumer products and drug delivery applications

Effects of sediment-associated copper to the deposit-feeding snail, \u3ci\u3ePotamopyrgus antipodarum\u3c/i\u3e: A comparison of Cu added in aqueous form or as nano- and micro-CuO particles

Increasing use of engineered nanoparticles (NPs) is likely to result in release of these particles to the aquatic environment where the NPs may eventually accumulate in sediment. However, little is known about the potential ecotoxicity of sediment-associated engineered NPs. We here consider the case of metal oxide NPs using CuO to understand if the effects of NPs differ from micron-sized particles of CuO and aqueous Cu (CuCl2). To address this issue, we compared effects of copper added to the sediment as aqueous Cu, nano- (6 nm) and micro- (μm) CuO particles on the deposit-feeding snail, Potamopyrgus antipodarum. Effects were assessed as mortality, specific growth rate, feeding rate, reproduction, and bioaccumulation after 8 weeks of exposure to nominal concentrations of 0, 30, 60, 120 and 240 μg Cu/g dry weight sediment. The results demonstrate that copper added to sediment as nano-CuO had greater effects on growth, feeding rate, and reproduction of P. antipodarum than copper added as micro-CuO or aqueous Cu. P. antipodarum accumulated more copper in the nano-CuO treatment than in aqueous Cu or micro-CuO treatments, indicating that consideration of metal form may be important when assessing risks of metals to the aquatic environment

Bioaccumulation and effects of sediment-associated gold- and graphene oxide nanoparticles on Tubifex tubifex

With the development of nanotechnology, gold (Au) and graphene oxide (GO) nanoparticles have been widely used in various fields, resulting in an increased release of these particles into the environment. The released nanoparticles may eventually accumulate in sediment, causing possible ecotoxicological effects to benthic invertebrates. However, the impact of Au-NPs and GO-NPs on the cosmopolitan oligochaete, Tubifex tubifex, in sediment exposure is not known. Mortality, behavioral impact (GO-NP and Au-NP) and uptake (only Au-NP) of sediment-associated Au-NPs (4.9 +/- 0.14 nm) and GO-NPs (116 +/- 0.05 nm) to T. tubifex were assessed in a number of 5-day exposure experiments. The results showed that the applied Au-NP concentrations (10 and 60 mu g Au/g dry weight sediment) had no adverse effect on T. tubifex survival, while Au bioaccumulation increased with exposure concentration. In the case of GO-NPs, no mortality of T. tubifex was observed at a concentration range of 20 and 180 mu g GO/g dry weight sediment, whereas burrowing activity was significantly reduced at 20 and 180 mu g GO/g dry weight sediment. Our results suggest that Au-NPs at 60 mu gAu/gorGO-NPs at 20 and 180 mu g GO/g were detected by T. tubifex as toxicants during short-termexposures. (C) 2016 The Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences. Published by Elsevier B.V

Importance of characterizing nanoparticles before conducting toxicity tests

Rapidly expanding growth in the field of nanotechnology has led to the development of numerous applications of nanomaterials in industrial (e.g., paints, electronics) and consumer (e.g., cosmetics, clothing treatments) products. These engineered nanoparticle (NP)-containing products have, however, the potential to release particles (single or aggregates) or ions by means of wastewater discharge into the aquatic environment. SCENIHR (2006) emphasized that the behavior of NPs is critically dependent on several particle characteristics, including size, surface area and surface reactivity, and that risk assessments for both human health and the environment have to be based on these characteristics. However, in practice, risks of NPs are in most cases assessed on the basis of their chemical composition alone and, to date, no widely accepted or well-defined risk assessment methods or test strategies exist explicitly designed for NPs