Assessing exposure, uptake and toxicity of silver and cerium dioxide nanoparticles from contaminated environments

The aim of this project was to compare cerium oxide and silver particles of different sizes for their potential for uptake by aquatic species, human exposure via ingestion of contaminated food sources and to assess their resultant toxicity. The results demonstrate the potential for uptake of nano and larger particles by fish via the gastrointestinal tract, and by human intestinal epithelial cells, therefore suggesting that ingestion is a viable route of uptake into different organism types. A consistency was also shown in the sensitivity of aquatic, fish cell and human cell models to Ag and CeO2 particles of different sizes; with the observed sensitivity sequence from highest to lowest as: nano-Ag > micro Ag > nano CeO2 = micro CeO2. Such consistency suggests that further studies might allow extrapolation of results between different models and species

An in vitro liver model - assessing oxidative stress and genotoxicity following exposure of hepatocytes to a panel of engineered nanomaterials

Background:Following exposure via inhalation, intratracheal instillation or ingestion some nanomaterials (NM) have been shown to translocate to the liver. Since oxidative stress has been implicated as a possible mechanism for NM toxicity this study aimed to investigate the effects of various materials (five titanium dioxide (TiO2), two zinc oxide (ZnO), two multi-walled carbon nanotubes (MWCNT) and one silver (Ag) NM) on oxidative responses of C3A cell line as a model for potential detrimental properties of nanomaterials on the liver.Results:We noted a dose dependant decrease in the cellular glutathione content following exposure of the C3A cells to Ag, the ZnO and the MWCNTs. Intracellular ROS levels were also measured and shown to increase significantly following exposure of the C3A to the low toxicity NMs (MWCNT and TiO2). The antioxidant Trolox in part prevented the detrimental effect of NMs on cell viability, and decreased the NM induced IL8 production after exposure to all but the Ag particulate. Following 4?hr exposure of the C3A cells to sub-lethal levels of the NMs, the largest amount of DNA damage was induced by two of the TiO2 samples (7?nm and the positively charged 10?nm particles).Conclusions:All ten NMs exhibited effects on the hepatocyte cell line that were at least in part ROS/oxidative stress mediated. These effects included mild genotoxicity and IL8 production for all NM except the Ag possibly due to its highly cytotoxic nature

In vitro assessment of engineered nanomaterials using a hepatocyte cell line: cytotoxicity, pro-inflammatory cytokines and functional markers.

Effects on the liver C3A cell line treated with a panel of engineered nanomaterials (NMs) consisting of two zinc oxide particles (ZnO; coated 100 nm and uncoated 130 nm), two multi-walled carbon nanotubes (MWCNTs), one silver (Ag < 20 nm), one 7 nm anatase, two rutile TiO2 nanoparticles (10 and 94 nm) and two derivatives with positive and negative covalent functionalisation of the 10 nm rutile were evaluated. The silver particles elicited the greatest level of cytotoxicity (24 h LC50 – 2 µg/cm2). The silver was followed by the uncoated ZnO (24 h LC50 – 7.5 µg/cm2) and coated ZnO (24 h LC50 – 15 µg/cm2) particles with respect to cytotoxicity. The ZnO NMs were found to be about 50–60% soluble which could account for their toxicity. By contrast, the Ag wa

Effects of silver nanoparticles on the liver and hepatocytes in vitro

With the increasing use and incorporation of nanoparticles (NPs) into consumer products, screening for potential toxicity is necessary to ensure customer safety. NPs have been shown to translocate to the bloodstream following inhalation and ingestion, and such studies demonstrate that the liver is an important organ for accumulation.Silver (Ag) NPs are highly relevant for human exposure due to their use in food contact materials, dietary supplements and antibacterial wound treatments. Due to the large number of different NPs already used in various products and being developed for new applications, it is essential that relevant quick and cheap methods of in vitro risk assessment suitable for these new materials are established. Therefore, this study used a simple hepatocytes model combined with an in vivo injection model to simulate the passage of a small amount of NPs into the bloodstream following exposure via for example ingestion or inhalation, and examined the potential of Ag NPs of 20 nm diameter to cause toxicity, inflammation and oxidative stress in the liver following in vivo exposures of female Wistar rats via intravenous injection to 50 &mu;g of NPs, and in vitro using the human hepatocyte cell line C3A.We found that Ag NPs were highly cytotoxic to hepatocytes (LC(50) LDH: 2.5 &mu;g/cm(2)), and affected hepatocyte homeostasis by reducing albumin release. At sub-lethal concentrations with normal cell or tissue morphology, Ag NPs were detected in cytoplasm and nuclei of hepatocytes. We observed similar effects of Ag NPs on inflammatory mediator expression in vitro and in vivo, with increase of IL-8/MIP-2, IL-1RI and TNF-&alpha; expression in both models and increased IL-8 protein release in vitro.This study presents evidence of the potential toxicity and inflammogenic potential of Ag NPs in the liver following ingestion. In addition, the similarities between in vitro and in vivo responses are striking, and encouraging for future reduction, refinement and replacement of animal studies by the use of hepatocyte cell lines in particle risk assessment

Fiber transmission and generation of ultrawideband pulses by direct current modulation of semi-conductor lasers and chirp-to-intensity conversion

Optical pulses generated by current modulation of semiconductor lasers are strongly frequency chirped. This effect has been considered pernicious for optical communications. We take advantage of this effect for the generation of ultrawideband microwave signals by using an optical filter to achieve chirp-to-intensity conversion. We also experimentally achieve propagation through a 20 km nonzero dispersion shifted fiber with no degradation of the signal at the receiver. Our method constitutes a prospective low-cost solution and offers integration capabilities with fiber-to-the-customer-premise system