Tag Archives: multiwalled carbon nanotubes

More from PETA (People for the Ethical Treatment of Animals) about nanomaterials and lungs

Science progress by increments. First, there was this April 27, 2016 post featuring some recent work by the organization, People for the Ethical Treatment of Animals (PETA) focused on nanomaterials and lungs. Now approximately one month later, PETA announces a new paper on the topic according to a May 26, 2016 news item on phys.org,

A scientist from the PETA International Science Consortium Ltd. is the lead author of a review on pulmonary fibrosis that results from inhaling nanomaterials, which has been published in Archives of Toxicology. The coauthors are scientists from Health Canada, West Virginia University, and the University of Fribourg in Switzerland.

A May 26, 2016 PETA news release on EurekAlert, which originated the news item, provides more detail (Note: Links have been removed),

The increasing use of nanomaterials in consumer goods such as paint, building materials, and food products has increased the likelihood of human exposure. Inhalation is one of the most prominent routes by which exposure can occur, and because inhalation of nanomaterials may be linked to lung problems such as pulmonary fibrosis, testing is conducted to assess the safety of these materials.

The review is one part of the proceedings of a 2015 workshop [mentioned in my Sept. 3, 2015 posting] organized by the PETA International Science Consortium, at which scientists discussed recommendations for designing an in vitro approach to assessing the toxicity of nanomaterials in the human lung. The workshop also produced another report that was recently published in Archives of Toxicology (Clippinger et al. 2016) and a review published in Particle and Fibre Toxicology (Polk et al. 2016) [mentioned in my April 27, 2016 posting] on exposing nanomaterials to cells grown in vitro.

The expert recommendations proposed at the workshop are currently being used to develop an in vitro system to predict the development of lung fibrosis in humans, which is being funded by the Science Consortium.

“International experts who took part in last year’s workshop have advanced the understanding and application of non-animal methods of studying nanomaterial effects in the lung,” says Dr. Monita Sharma, nanotoxicology specialist at the Consortium and lead author of the review in Archives of Toxicology. “Good science is leading the way toward more humane testing of nanomaterials, which, in turn, will lead to better protection of human health.”

Here’s a link to and a citation for the paper,

Predicting pulmonary fibrosis in humans after exposure to multi-walled carbon nanotubes (MWCNTs) by Monita Sharma, Jake Nikota, Sabina Halappanavar, Vincent Castranova, Barbara Rothen-Rutishauser, Amy J. Clippinger. Archives of Toxicology pp 1-18 DOI: 10.1007/s00204-016-1742-7 First online: 23 May 2016

This paper is behind a paywall.

Cute, adorable roundworms help measure nanoparticle toxicity

Caption: Low-cost experiments to test the toxicity of nanomaterials focused on populations of roundworms. Rice University scientists were able to test 20 nanomaterials in a short time, and see their method as a way to determine which nanomaterials should undergo more extensive testing. Credit: Zhong Lab/Rice University

Caption: Low-cost experiments to test the toxicity of nanomaterials focused on populations of roundworms. Rice University scientists were able to test 20 nanomaterials in a short time, and see their method as a way to determine which nanomaterials should undergo more extensive testing.
Credit: Zhong Lab/Rice University

Until now, ‘cute’ and ‘adorable’ are not words I would have associated with worms of any kind or with Rice University, for that matter. It’s amazing what a single image can do, eh?

A Feb. 3, 2015 news item on Azonano describes how roundworms have been used in research investigating the toxicity of various kinds of nanoparticles,

The lowly roundworm is the star of an ambitious Rice University project to measure the toxicity of nanoparticles.

The low-cost, high-throughput study by Rice scientists Weiwei Zhong and Qilin Li measures the effects of many types of nanoparticles not only on individual organisms but also on entire populations.

A Feb. 2, 2015 Rice University news release (also on EurekAlert), which originated the news item, provides more details about the research,

The Rice researchers tested 20 types of nanoparticles and determined that five, including the carbon-60 molecules (“buckyballs”) discovered at Rice in 1985, showed little to no toxicity.

Others were moderately or highly toxic to Caenorhabditis elegans, several generations of which the researchers observed to see the particles’ effects on their health.

The results were published by the American Chemical Society journal Environmental Sciences and Technology. They are also available on the researchers’ open-source website.

“Nanoparticles are basically new materials, and we don’t know much about what they will do to human health and the health of the ecosystem,” said Li, an associate professor of civil and environmental engineering and of materials science and nanoengineering. “There have been a lot of publications showing certain nanomaterials are more toxic than others. So before we make more products that incorporate these nanomaterials, it’s important that we understand we’re not putting anything toxic into the environment or into consumer products.

“The question is, How much cost can we bear?” she said. “It’s a long and expensive process to do a thorough toxicological study of any chemical, not just nanomaterials.” She said that due to the large variety of nanomaterials being produced at high speed and at such a large scale, there is “an urgent need for high-throughput screening techniques to prioritize which to study more extensively.”

Rice’s pilot study proves it is possible to gather a lot of toxicity data at low cost, said Zhong, an assistant professor of biosciences, who has performed extensive studies on C. elegans, particularly on their gene networks. Materials alone for each assay, including the worms and the bacteria they consumed and the culture media, cost about 50 cents, she said.

The researchers used four assays to see how worms react to nanoparticles: fitness, movement, growth and lifespan. The most sensitive assay of toxicity was fitness. In this test, the researchers mixed the nanoparticles in solutions with the bacteria that worms consume. Measuring how much bacteria they ate over time served as a measure of the worms’ “fitness.”

“If the worms’ health is affected by the nanoparticles, they reproduce less and eat less,” Zhong said. “In the fitness assay, we monitor the worms for a week. That is long enough for us to monitor toxicity effects accumulated through three generations of worms.” C. elegans has a life cycle of about three days, and since each can produce many offspring, a population that started at 50 would number more than 10,000 after a week. Such a large number of tested animals also enabled the fitness assay to be highly sensitive.

The researchers’ “QuantWorm” system allowed fast monitoring of worm fitness, movement, growth and lifespan. In fact, monitoring the worms was probably the least time-intensive part of the project. Each nanomaterial required specific preparation to make sure it was soluble and could be delivered to the worms along with the bacteria. The chemical properties of each nanomaterial also needed to be characterized in detail.

The researchers studied a representative sampling of three classes of nanoparticles: metal, metal oxides and carbon-based. “We did not do polymeric nanoparticles because the type of polymers you can possibly have is endless,” Li explained.

They examined the toxicity of each nanoparticle at four concentrations. Their results showed C-60 fullerenes, fullerol (a fullerene derivative), titanium dioxide, titanium dioxide-decorated nanotubes and cerium dioxide were the least damaging to worm populations.

Their “fitness” assay confirmed dose-dependent toxicity for carbon black, single- and multiwalled carbon nanotubes, graphene, graphene oxide, gold nanoparticles and fumed silicon dioxide.

They also determined the degree to which surface chemistry affected the toxicity of some particles. While amine-functionalized multiwalled nanotubes proved highly toxic, hydroxylated nanotubes had the least toxicity, with significant differences in fitness, body length and lifespan.

A complete and interactive toxicity chart for all of the tested materials is available online.

Zhong said the method could prove its worth as a rapid way for drug or other companies to narrow the range of nanoparticles they wish to put through more expensive, dedicated toxicology testing.

“Next, we hope to add environmental variables to the assays, for example, to mimic ultraviolet exposure or river water conditions in the solution to see how they affect toxicity,” she said. “We also want to study the biological mechanism by which some particles are toxic to worms.”

Here’s a citation for the paper and links to the paper and to the researchers’ website,

A multi-endpoint, high-throughput study of nanomaterial toxicity in Caenorhabditis elegans by Sang-Kyu Jung, Xiaolei Qu, Boanerges Aleman-Meza, Tianxiao Wang, Celeste Riepe, Zheng Liu, Qilin Li, and Weiwei Zhong. Environ. Sci. Technol., Just Accepted Manuscript DOI: 10.1021/es5056462 Publication Date (Web): January 22, 2015
Copyright © 2015 American Chemical Society

Nanomaterial effects on C. elegans

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This heat map indicates whether a measurement for the nanomaterial-exposed worms is higher (yellow), or lower (blue) than the control worms. Black indicates no effects from nanomaterial exposure.

Clicking on colored blocks to see detailed experimental data.

The published paper is open access but you need an American Chemical Society site registration to access it. The researchers’ site is open access.