Tag Archives: CEINT

Investigating nanoparticles and their environmental impact for industry?

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It seems the Center for the Environmental Implications of Nanotechnology (CEINT) at Duke University (North Carolina, US) is making an adjustment to its focus and opening the door to industry, as well as, government research. It has for some years (my first post about the CEINT at Duke University is an Aug. 15, 2011 post about its mesocosms) been focused on examining the impact of nanoparticles (also called nanomaterials) on plant life and aquatic systems. This Jan. 9, 2017 US National Science Foundation (NSF) news release (h/t Jan. 9, 2017 Nanotechnology Now news item) provides a general description of the work,

We can’t see them, but nanomaterials, both natural and manmade, are literally everywhere, from our personal care products to our building materials–we’re even eating and drinking them.

At the NSF-funded Center for Environmental Implications of Nanotechnology (CEINT), headquartered at Duke University, scientists and engineers are researching how some of these nanoscale materials affect living things. One of CEINT’s main goals is to develop tools that can help assess possible risks to human health and the environment. A key aspect of this research happens in mesocosms, which are outdoor experiments that simulate the natural environment – in this case, wetlands. These simulated wetlands in Duke Forest serve as a testbed for exploring how nanomaterials move through an ecosystem and impact living things.

CEINT is a collaborative effort bringing together researchers from Duke, Carnegie Mellon University, Howard University, Virginia Tech, University of Kentucky, Stanford University, and Baylor University. CEINT academic collaborations include on-going activities coordinated with faculty at Clemson, North Carolina State and North Carolina Central universities, with researchers at the National Institute of Standards and Technology and the Environmental Protection Agency labs, and with key international partners.

The research in this episode was supported by NSF award #1266252, Center for the Environmental Implications of NanoTechnology.

Miles O’Brien, Science Nation Correspondent
Ann Kellan, Science Nation Producer

The mention of industry is in this video by O’Brien and Kellan, which describes CEINT’s latest work ,

Somewhat similar in approach although without a direction reference to industry, Canada’s Experimental Lakes Area (ELA) is being used as a test site for silver nanoparticles. Here’s more from the Distilling Science at the Experimental Lakes Area: Nanosilver project page,

Water researchers are interested in nanotechnology, and one of its most commonplace applications: nanosilver. Today these tiny particles with anti-microbial properties are being used in a wide range of consumer products. The problem with nanoparticles is that we don’t fully understand what happens when they are released into the environment.

The research at the IISD-ELA [International Institute for Sustainable Development Experimental Lakes Area] will look at the impacts of nanosilver on ecosystems. What happens when it gets into the food chain? And how does it affect plants and animals?

Here’s a video describing the Nanosilver project at the ELA,

You may have noticed a certain tone to the video and it is due to some political shenanigans, which are described in this Aug. 8, 2016 article by Bartley Kives for the Canadian Broadcasting Corporation’s (CBC) online news.

Of airborne nanomaterials, bacterial microbiomes, viral microbiomes, and paper sensors

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There’s a Jan. 14, 2015 news item on Nanowerk from the Virginia Polytechnic Institute (Virginia Tech) which is largely a personal profile featuring some basic information (useful for those new to the topic) about airborne nanoparticles (Note: A link has been removed),

The Harvard educated undergraduate [Linsey Marr,  professor of civil and environmental engineering, Virginia Tech] who obtained her Ph.D. from University of California at Berkeley and trained as a postdoctoral researcher with a Nobel laureate of chemistry at MIT is now among a handful of researchers in the world who are addressing concerns about engineered nanomaterials in the atmosphere.

Marr is part of the National Science Foundation’s Center for the Environmental Implications of Nanotechnology and her research group has characterized airborne nanoparticles at every point of their life cycle. This cycle includes production at a commercial manufacturing facility, use by consumers in the home, and disposal via incineration.

A Jan. 14, 2015 Virginia Tech news release, which originated the news item, quotes Marr on the current thinking about airborne nanoparticles,

“Results have shown that engineered nanomaterials released into the air are often aggregated with other particulate matter, such as combustion soot or ingredients in consumer spray products, and that the size of such aggregates may range from smaller than 10 nanometers to larger than 10 microns,” Marr revealed. She was referring to studies completed by research group members Marina Quadros Vance of Florianopolis, Brazil, a research scientist with the Virginia Tech Institute of Critical Technology and Applied Science, and Eric Vejerano, of Ligao, Philippines, a post-doctoral associate in civil and environmental engineering.

Size matters if these aggregates are inhaled.

Another concern is the reaction of a nanomaterial such as a fullerene with ozone at environmentally relevant concentration levels. Marr’s graduate student, Andrea Tiwari, of Mankato, Minnesota, said the resulting changes in fullerene could lead to enhanced toxicity.

The story then segues into airborne pathogens and viruses eventually honing in on virus microbiomes and bacterial microbiomes (from the news release),

Marr is a former Ironman triathlete who obviously has strong interests in what she is breathing into her own body. So it would be natural for her to expand her study of engineered nanoparticles traveling in the atmosphere to focus on airborne pathogens.

She did so by starting to consider the influenza virus as an airborne pollutant. She applied the same concepts and tools used for studying environmental contaminants and ambient aerosols to the examination of the virus.

She looked at viruses as “essentially self-assembled nanoparticles that are capable of self-replication.”

Her research team became the first to measure influenza virus concentrations in ambient air in a children’s day care center and on airplanes. When they conducted their studies, the Virginia Tech researchers collected samples from a waiting room of a health care center, two toddlers’ rooms and one babies’ area of a childcare center, as well as three cross-country flights between Roanoke, Virginia., and San Francisco. They collected 16 samples between Dec. 10, 2009 and Apr. 22, 2010.

“Half of the samples were confirmed to contain aerosolized influenza A viruses,” Marr said. The childcare samples were the most infected at 75 percent. Next, airplane samples reached 67 percent contamination, and health center numbers came in at 33 percent.

This study serves as a foundation for new work started about a year ago in her lab.

Marr collaborated with Aaron J. Prussin II, of Blacksburg, Virginia, and they successfully secured for him a postdoctoral fellowship from the Alfred P. Sloan Foundation to characterize the bacterial and viral microbiome — the ecological community of microorganisms — of the air in a daycare center.

They are now attempting to determine seasonal changes of both the viral microbiome and the bacterial microbiome in a daycare setting, and examine how changes in the microbiome are related to naturally occurring changes in the indoor environment.

“Little is known about the viral component of the microbiome and it is important because viruses are approximately 10 times more abundant than bacteria, and they help shape the bacterial community. Research suggests that viruses do have both beneficial and harmful interactions with bacteria,” Prussin said.

With Prussin and Marr working together they hope to verify their hypothesis that daycare centers harbor unique, dynamic microbiomes with plentiful bacteria and viruses. They are also looking at what seasonal changes might bring to a daycare setting.

They pointed to the effect of seasonal changes because in previous work, Marr, her former graduate student Wan Yang, of Shantou, China, and Elankumaran Subbiah, a virologist in the biomedical sciences and pathobiology department of the Virginia-Maryland College of Veterinary Medicine, measured the influenza A virus survival rate at various levels of humidity.

Their 2012 study presented for the first time the relationship between the influenza A virus viability in human mucus and humidity over a large range of relative humidities, from 17 percent to 100 percent. They found the viability of the virus was highest when the relative humidity was either close to 100 percent or below 50 percent. The results in human mucus may help explain influenza’s seasonality in different regions.

According to the news release Marr and her colleagues have developed a fast and cheap technology for detection of airborne pathogens (Note: A link has been removed),

With the urgent need to understand the dynamics of airborne pathogens, especially as one considers the threats of bioterrorism, pandemic influenza, and other emerging infectious diseases, Marr said “a breakthrough technology is required to enable rapid, low-cost detection of pathogens in air.”

Along with Subbiah and Peter Vikesland,  professor of civil and environmental engineering, they want to develop readily deployable, inexpensive, paper-based sensors for airborne pathogen detection.

In 2013 they received funding of almost $250,000 from Virginia Tech’s Institute for Critical Technology and Applied Science, a supporter of the clustering of research groups, to support their idea of creating paper-based sensors based on their various successes to date.

Marr explained the sensors “would use a sandwich approach. The bottom layer is paper containing specialized DNA that will immobilize the virus. The middle layer is the virus, which sticks to the specialized DNA on the bottom layer. The top layer is additional specialized DNA that sticks to the virus. This DNA is attached to gold nanoparticles that are easily detectable using a technique known as Raman microscopy.”

They key to their approach is that it combines high-tech with low-tech in the hopes of keeping the assay costs low. Their sampling method will use a bicycle pump, and low cost paper substrates. They hope that they will be able to incorporate smart-phone based signal transduction for the detection. Using this approach, they believe “even remote corners of the world” would be able to use the technique.

Vikesland previously received funding from the Gates Foundation to detect the polio virus via paper-based diagnostics. Polio is still found in countries on the continents of Asia and Africa.

I have previously mentioned Linsey Marr in an Oct. 18, 2013 post about the revival of the Nanotechnology Consumer Products Inventory (originally developed by the Project for Emerging Nanotechnologies) by academics at Virginia Tech and first mentioned CEINT in an Aug. 15, 2011 post about a special project featuring a mesocosm at Duke University (North Carolina).

Carbon nanotube accumulation in Duke University’s (US) mesocosm

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This Oct. 1, 2014 news item on ScienceDaily about carbon nanotubes accumulating in the wetlands is carefully worded,

A Duke University team has found that nanoparticles called single-walled carbon nanotubes accumulate quickly in the bottom sediments of an experimental wetland setting, an action they say could indirectly damage the aquatic food chain. [emphasis mine]

The results indicate little risk to humans ingesting the particles through drinking water, say scientists at Duke’s Center for the Environmental Implications of Nanotechnology (CEINT). But the researchers warn that, based on their previous research, the tendency for the nanotubes to accumulate in sediment could indirectly damage the aquatic food chain in the long term if the nanoparticles provide “Trojan horse” piggyback rides to other harmful molecules. [emphases mine]

There’s a lot of hedging (could, if) in the way this research is being described. I imagine the researchers are indicating they have concerns but have no wish to stimulate panic and worry.

An Oct. 1, 2014 Duke University news release (also on EurekAlert), which originated the news item, goes on to explain the interest in carbon nanotubes specifically,

Carbon nanotubes are rapidly becoming more common because of their usefulness in nanoelectric devices, composite materials and biomedicine.

The Duke study was done using small-scale replications of a wetland environment, called “mesocosms,” that include soil, sediments, microbes, insects, plants and fish. These ecosystems-in-a-box are “semi-closed,” meaning they get fresh air and rainwater but don’t drain to their surroundings. While not perfect representations of a natural environment, mesocosms provide a reasonable compromise between the laboratory and the real world.

“The wetland mesocosms we used are a much closer approximation of the natural processes constantly churning in the environment,” said Lee Ferguson, associate professor of civil and environmental engineering at Duke. “Although it’s impossible to know if our results are fully accurate to natural ecosystems, it is clear that the processes we’ve seen should be considered by regulators and manufacturers.”

Ferguson and his colleagues dosed the mesocosms with single-walled carbon nanotubes and measured their concentrations in the water, soil and living organisms during the course of a year. They found that the vast majority of the nanoparticles quickly accumulated in the sediment on the “pond” floor. However, they found no sign of nanoparticle buildup in any plants, insects or fish living in the mesocosms.

That sounds marvelous and then the researchers provide a few facts about carbon nanotubes,

While this is good news for humans or other animals drinking water after a potential spill or other contamination event, the accumulation in sediment does pose concerns for both sediment-dwelling organisms and the animals that eat them. Previous research has shown that carbon nanotubes take a long time to degrade through natural processes — if they do at all — and any chemical that binds to them cannot easily be degraded either.

“These nanoparticles are really good at latching onto other molecules, including many known organic contaminants,” said Ferguson. “Coupled with their quick accumulation in sediment, this may allow problematic chemicals to linger instead of degrading. The nanoparticle-pollutant package could then be eaten by sediment-dwelling organisms in a sort of ‘Trojan horse’ effect, allowing the adsorbed contaminants to accumulate up the food chain.

“The big question is whether or not these pollutants can be stripped away from the carbon nanotubes by these animals’ digestive systems after being ingested,” continued Ferguson. “That’s a question we’re working to answer now.”

It’s good to see this research is being followed up so quickly. I will keep an eye out for it and, in the meantime, wonder how the followup research will be conducted and what animals will be used for the tests.

Here’s a link to and a citation for the researchers’ most recent paper on possible ‘Trojan’ carbon nanotubes,

Fate of single walled carbon nanotubes in wetland ecosystems by Ariette Schierz, Benjamin Espinasse, Mark R. Wiesner, Joseph H. Bisesi, Tara Sabo-Attwood, and P. Lee Ferguson. Environ. Sci.: Nano, 2014, Advance Article DOI: 10.1039/C4EN00063C First published online 03 Sep 2014

This is an open access paper.

I have written about Duke University and its nanoparticle research in mesocosms before. Most recently, there was a Feb. 28, 2013 posting about work on silver nanoparticles which mentions research in the ‘mesocosm’ (scroll down about 50% of the way). There’s also an Aug. 15, 2011 posting which describes the ‘mesocosm’ project at some length.

For anyone unfamiliar with the Trojan horse story (from its Wikipedia entry; Note: Links have been removed),

The Trojan Horse is a tale from the Trojan War about the subterfuge that the Greeks used to enter the city of Troy and win the war. In the canonical version, after a fruitless 10-year siege, the Greeks constructed a huge wooden horse, and hid a select force of men inside. The Greeks pretended to sail away, and the Trojans pulled the horse into their city as a victory trophy. That night the Greek force crept out of the horse and opened the gates for the rest of the Greek army, which had sailed back under cover of night. The Greeks entered and destroyed the city of Troy, decisively ending the war.

Duke University’s (North Carolina, US) Center for Environmental Implications of NanoTechnology (CEINT) wins $15M grant

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A Nov. 13, 2013 news item on Azonano announces that the Center for Environmental Implications of Nanotechnology (CEINT) at Duke University has been awarded $15M,

A pioneering, multi-institution research center headquartered at Duke’s Pratt School of Engineering has just won $15-million grant renewal from the National Science Foundation and the US Environmental Protection Agency to continue learning more about where nanoparticles accumulate, how they interact with other chemicals and how they affect the environment.

Founded in 2008, the Center for Environmental Implications of NanoTechnology (CEINT) has been evaluating the effect of long-term nanomaterial exposure on organisms and ecosystems.

“The previous focus has been on studying simple, uniform nanomaterials in simple environments,” said Mark Wiesner, James L. Meriam Professor of Civil & Environmental Engineering and director of CEINT. “As we look to the next five years, we envision a dramatically different landscape. We will be evaluating more complex nanomaterials in more realistic natural environments such as agricultural lands and water treatment systems where these materials are likely to be found.”

The Nov. 11, 2013 Duke University news release by Karyn Hede, which originated the news item, provides some history and context for CEINT (Note: Links have been removed),

When CEINT formed, little research had been done on how materials manufactured at the nanoscale—about 1/10,000th the diameter of a human hair—enter the environment and whether their size and unique properties render them a new category of environmental risk. For example, nanoparticles can be highly reactive with other chemicals in the environment and had been shown to disrupt activities in living organisms. Indeed, nanosilver is used in clothing precisely because it effectively kills odor-causing bacteria.

To tackle this expansive research agenda, CEINT leadership assembled a multi-institutional research team encompassing expertise in ecosystems biology, chemistry, geology, materials science, computational science, mathematical modeling and other specialties, to complement its engineering expertise. The Center has 29 faculty collaborators, as well as 76 graduate and undergraduate students participating in research. Over its first five years, CEINT has answered some of the most pressing questions about environmental risk and has learned where to focus future research.

The center also pioneered the use of a new test chamber, called a mesocosm, that replicates a small wetland environment. “Over the long term, we want to evaluate how nanoparticles bioaccumulate in complex food webs,” said Emily Bernhardt, an associate professor of biology at Duke and ecosystem ecologist who helped design the simulated ecosystems. “The additional funding will allow us to study the subtle effect of low-dose exposure on ecosystems over time, as well as complex interactions among nanoparticles and other environmental contaminants.”

Looking forward, the investigators at CEINT plan to expand the use of systems modeling and to create a “knowledge commons,” a place to store various kinds of data that can then be analyzed as a whole, said CEINT Executive Director Christine Hendren.

“Our investigators and collaborators are located across the globe,” Hendren added. “We are committed to disseminating information that can be translated into responsible regulatory frameworks and that will be available to compare with results of future research.”

…

Key findings from CEINT’s first five years include:

Naturally occurring nanomaterials far outnumber engineered particles. CEINT scientist Michael Hochella, a geoscientist at Virginia Tech, inventoried nanoparticles and concluded that natural nanoparticles are found everywhere, from dust in the atmosphere to sea spray to volcanoes. The environmental risks of these natural nanomaterials are difficult to separate from engineered nanomaterials.

Engineered nanoparticles change once they enter the environment. Gregory V. Lowry, deputy director of CEINT and professor at Carnegie Mellon University, Pittsburgh, along with colleagues from the University of Birmingham, U.K. and the University of South Carolina found that the relatively large surface area of nanoparticles makes them highly reactive once they enter the environment. These transformations will alter their movement and toxicity and must be considered when studying nanomaterials. Their review article on this topic was named the best feature article of 2012 by the journal Environmental Science and Technology.

Nanoparticles can be visualized, even in complex environmental samples. A research team led by CEINT investigators Jie Liu, associate professor of chemistry at Duke, and CEINT Director Mark Wiesner showed that more than a dozen types of engineered nanoparticles, including silver, gold, and titanium dioxide, along with carbon nanotubes, can be surveyed using a technique called hyperspectral imaging, which measures light scattering caused by different types of nanoparticles. The new technique, co-developed by postdoctoral researcher Appala Raju Badireddy, is sensitive enough to analyze nanoparticles found in water samples ranging from ultrapurified to wastewater. It will be used in future long-term studies of how nanoparticles move and accumulate in ecological systems.

It is possible to estimate current and future volume of engineered nanomaterials. Understanding the volume of nanomaterials being produced and released into the environment is a crucial factor in risk assessment. CEINT researchers led by Christine Hendren measured the upper- and lower-bound annual U.S. production of five classes of nanomaterials, totaling as much as a combined 40,000 metric tons annually as of 2011.

Silver nanoparticles caused environmental stress in a simulated wetland environment. CEINT has developed  “mesocosms,”  open-air terrarium-like structures that simulate wetland ecosystems that can be evaluated over time. Even low doses of silver nanoparticles used in many consumer products produced about a third less biomass in a mesocosm. The researchers will now  look at how nanomaterials are transferred between organisms in a mesocosm.

I have written about CEINT and its work, including the mesocosm, many times. My August 15, 2011 posting offers an introduction to the CEINT mesocosm.

Silver nanoparticles: we love you/we hate you

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We seem to have a love/hate affair with silver nanoparticles. Long recognized as biocides capable of killing bacteria, silver nanoparticles are used both in hospital settings and in sports wear. As the use of silver nanoparticles increases, there are concerns about unintended consequences to the environment and to human health. An Apr. 12, 2013 news item on Nanowerk highlights some research done in Europe in 2011 (Note: Links have been removed),

As part of an EU funded project called Prosuite, Walser [Tobias Walser, researcher at the Institute for environmental engineering at the Swiss Federal Institute of Technology Zürich {ETH}] and colleagues analysed the environmental impact of nanosilver T-shirts during their entire life cycle, from raw material extraction to end-of-life disposal (“Prospective Environmental Life Cycle Assessment of Nanosilver T-Shirts”). This, according to Walser, is the first of its kind for a nanomaterial. The scientists found that the T-shirt’s environmental impact during use would be reduced if they are washed less often than conventional ones, due to their antimicrobial properties. This would even compensate for a slightly higher climate footprint during production. Walser explains: “In comparison to all toxic releases during the life cycle of a T-shirt, the toxic releases from nanosilver from washing appear to be of minor relevance.” [emphasis mine]

The Apr. 11, 2013 article by Constanze Böttcher for Youris.com, which originated the news item, expands on the theme of toxicity, nanosilver, and wastewater (Note: A link has been removed),

Previous studies looked at single impacts of antibacterial textiles. For example, scientists found that nanosilver leaches into the wastewater during washing. According to other studies, this silver may not be that harmful to the environment because it is transformed into a nearly insoluble substance called silver sulphide in wastewater treatments. A study published by the Danish Environmental Protection Agency in 2012 did not find “specific risks” to health or environmental effects of nanosilver textiles available in Denmark.

This finding contrasts with more recent research at Duke University’s CEINT (Center for Environmental Implications of Nanotechnology) mesocosm project where a study did point to adverse responses (noted in my Feb. 28, 2013 posting where I highlighted two nanosilver environmental studies, a Finnish/Estonian research project and the CEINT project),

In experiments mimicking a natural environment, Duke University researchers have demonstrated that the silver nanoparticles used in many consumer products can have an adverse effect on plants and microorganisms.

…

The main route by which these particles enter the environment is as a by-product of water and sewage treatment plants. [emphasis] The nanoparticles are too small to be filtered out, so they and other materials end up in the resulting “sludge,” which is then spread on the land surface as a fertilizer.

…

The researchers found that one of the plants studied, a common annual grass known as Microstegium vimeneum, had 32 percent less biomass in the mesocosms treated with the nanoparticles. Microbes were also affected by the nanoparticles, Colman [Benjamin Colman, a post-doctoral fellow in Duke’s biology department and a member of the Center for the Environmental Implications of Nanotechnology (CEINT)] said. One enzyme associated with helping microbes deal with external stresses was 52 percent less active, while another enzyme that helps regulate processes within the cell was 27 percent less active. The overall biomass of the microbes was also 35 percent lower, he said.

As I’ve suggested before, analysing the impact that new products and materials may have on the environment and on our health is a complex process.  From Böttcher’s 2013 article (Note: Links have been removed),

Some experts are concerned about their environmental risks, however. The study “is very relevant” because it “gives a fingerprint” about the impact of such T-shirts, Anders Baun says. But the professor in risk assessment of nanomaterials at the department of environmental engineering at the Technical University of Denmark, based in Lyngby, considers it “a bad idea to distribute silver in the environment”. He points to a study that found evidence for nanosilver accumulating in the food web based on a study of plants and animals of an experimental wetland environment. Moreover, he says, it is unknown how the coating of nanosilver influences its environmental behaviour. Baun has previously criticised the European policies regarding nanosilver and is currently enrolled in a scientific committee on the topic as invited expert. The expert group will publish its opinion later this year, he says.

There’s also the possibility that bacteria will develop resistance with increased use of silver nanoparticles in medical environments and in sportswear and in other applications.

For those who want to conduct their own investigations, here’s a link to and a citation for Walser’s 2011 paper,

Prospective Environmental Life Cycle Assessment of Nanosilver T-Shirts by Tobias Walser, Evangelia Demou, Daniel J. Lang, and Stefanie Hellweg.  Environ. Sci. Technol [Environmental Science and Technology], 2011, 45 (10), pp 4570–4578 DOI: 10.1021/es2001248 Publication Date (Web): April 20, 2011
Copyright © 2011 American Chemical Society

This paper is open access.

A description of PROSUITE (PROspective SUstaInability assessment of TEchnologies project) can be found here and the PROSUITE project website can found here.

ETA Apr. 18, 2013: An Apr. 18, 2013 news item (Barely any nanosilver from consumer products in the water) on Nanowerk provides some insight into why at least one European country views the presence of silver nanoparticles in sewage sludge without any particular alarm,

The study did not examine what happens to nanosilver in the sewage sludge thereafter. In Switzerland, it is not permissible to use sewage sludge on farmland, and most of the sludge is therefore burned. [emphasis mine] The heavy metals separated in this process should not be released into the environment in large quantities.

Here’s a link to and citation for the Swiss study,

Fate and transformation of silver nanoparticles in urban wastewater systems by Ralf Kaegia, Andreas Voegelina, Christoph Orta, Brian Sinneta, Basilius Thalmanna, Jasmin Krismerb, Harald Hagendorferc, Maline Elumelua, and Elisabeth Muellerd. Water Research, http://dx.doi.org/10.1016/j.watres.2012.11.060 Available online 26 March 2013

The article is behind a paywall.

Silver nanoparticles, water, the environment, and toxicity

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I am contrasting two very different studies on silver nanoparticles in water and their effect on the environment to highlight the complex nature of determining the risks and environmental effects associated with nanoparticles in general. One piece of research suggests that silver nanoparticles are less dangerous than other commonly used forms of silver while the other piece raises some serious concerns.

A Feb. 28, 2013 news item on Nanowerk features research about the effects that silver nanoparticles have on aquatic ecosystems (Note: A link has been removed),

According to Finnish-Estonian joint research with data obtained on two crustacean species, there is apparently no reason to consider silver nanoparticles more dangerous for aquatic ecosystems than silver ions.

The results were reported in the journal Environmental Science and Pollution Research late last year (“Toxicity of two types of silver nanoparticles to aquatic crustaceans Daphnia magna and Thamnocephalus platyurus”). Jukka Niskanen has utilised the same polymerisation and coupling reactions in his doctoral dissertation studying several hybrid nanomaterials, i.e. combinations of synthetic polymers and inorganic (gold, silver and montmorillonite) nanoparticles. Niskanen will defend his doctoral thesis at the University of Helsinki in April.

The University of Helsikinki Feb. 28, 2013 press release written by Minna Merilainen and which originated the new item provides details about the research,

“Due to the fact that silver in nanoparticle form is bactericidal and also fungicidal and also prevents the reproduction of those organisms, it is now used in various consumer goods ranging from wound dressing products to sportswear,” says Jukka Niskanen from the Laboratory of Polymer Chemistry at the University of Helsinki, Finland.A joint study from the University of Helsinki and the National Institute of Chemical Physics and Biophysics (Tallinn, Estonia), Toxicity of two types of silver nanoparticles to aquatic crustaceans Daphnia magna and Thamnocephalus platyurus, shows that silver nanoparticles are apparently no more hazardous to aquatic ecosystems than a water-soluble silver salt. The study compared the ecotoxicity of silver nanoparticles and a water-soluble silver salt.

“Our conclusion was that the environmental risks caused by silver nanoparticles are seemingly not higher than those caused by a silver salt. However, more research is required to reach a clear understanding of the safety of silver-containing particles,” Niskanen says.

Indeed, silver nanoparticles were found to be ten times less toxic than the soluble silver nitrate - a soluble silver salt used for the comparison.

The bioavailability of silver varies in different test media

To explain this phenomenon, the researchers refer to the variance in the bioavailability of silver to crustaceans in different tested media.

University lecturer Olli-Pekka Penttinen from the Department of Environmental Sciences of the University of Helsinki goes on to note that the inorganic and organic compounds dissolved in natural waters (such as humus), water hardness and sulfides have a definite impact on the bioavailability of silver. Due to this, the toxicity of both types of tested nanoparticles and the silver nitrate measured in the course of the study was lower in natural water than in artificial fresh water.

The toxicity of silver nanoparticles and silver ions was studied using two aquatic crustaceans, a water flea (Daphnia magna) and a fairy shrimp ( Thamnocephalus platyurus). Commercially available protein-stabilised particles and particles coated with a water-soluble, non-toxic polymer, specifically synthesised for the purpose, were used in the study. First, the polymers were produced utilising a controlled radical polymerization method. Synthetic polymer-grafted silver particles were then produced by attaching the water-soluble polymer to the surface of the silver with a sulfur bond.

Jukka Niskanen has utilised such polymerisation and coupling reactions in his doctoral dissertation. Polymeric and hybrid materials: polymers on particle surfaces and air-water interfaces, studying several hybrid nanomaterials , i.e., combinations of synthetic polymers and inorganic (gold, silver and montmorillonite) nanoparticles....

It was previously known from other studies and research results that silver changes the functioning of proteins and enzymes. It has also been shown that silver ions can prevent the replication of DNA. Concerning silver nanoparticles, tests conducted on various species of bacteria and fungi have indicated that their toxicity varies. For example, gram-negative bacteria such as Escherichia coli are more sensitive to silver nanoparticles than gram-positive ones (such as Staphylococcus aureus). The difference in sensitivity is caused by the structural differences of the cell membranes of the bacteria. The cellular toxicity of silver nanoparticles in mammals has been studied as well. It has been suggested that silver nanoparticles enter cells via endocytosis and then function in the same manner as in bacterial cells, damaging DNA and hindering cell respiration. Electron microscope studies have shown that human skin is permeable to silver nanoparticles and that the permeability of damaged skin is up to four times higher than that of healthy skin.

While this Finnish-Estonian study suggests that silver nanoparticles do not have a negative impact on the tested crustaceans in an aquatic environment, there’s a study from Duke University suggests that silver nanoparticles in wastewater which is later put to agricultural use may cause problems. From the Feb. 27, 2013 news release on EurekAlert,

In experiments mimicking a natural environment, Duke University researchers have demonstrated that the silver nanoparticles used in many consumer products can have an adverse effect on plants and microorganisms.

…

The main route by which these particles enter the environment is as a by-product of water and sewage treatment plants. [emphasis] The nanoparticles are too small to be filtered out, so they and other materials end up in the resulting “sludge,” which is then spread on the land surface as a fertilizer.

…

The researchers found that one of the plants studied, a common annual grass known as Microstegium vimeneum, had 32 percent less biomass in the mesocosms treated with the nanoparticles. Microbes were also affected by the nanoparticles, Colman [Benjamin Colman, a post-doctoral fellow in Duke’s biology department and a member of the Center for the Environmental Implications of Nanotechnology (CEINT)] said. One enzyme associated with helping microbes deal with external stresses was 52 percent less active, while another enzyme that helps regulate processes within the cell was 27 percent less active. The overall biomass of the microbes was also 35 percent lower, he said.

“Our field studies show adverse responses of plants and microorganisms following a single low dose of silver nanoparticles applied by a sewage biosolid,” Colman said. “An estimated 60 percent of the average 5.6 million tons of biosolids produced each year is applied to the land for various reasons, and this practice represents an important and understudied route of exposure of natural ecosystems to engineered nanoparticles.”

“Our results show that silver nanoparticles in the biosolids, added at concentrations that would be expected, caused ecosystem-level impacts,” Colman said. “Specifically, the nanoparticles led to an increase in nitrous oxide fluxes, changes in microbial community composition, biomass, and extracellular enzyme activity, as well as species-specific effects on the above-ground vegetation.”

As previously noted, these two studies show just how complex the questions of risk and nanoparticles can become.  You can find out more about the Finish-Estonian study,

Toxicity of two types of silver nanoparticles to aquatic crustaceans Daphnia magna and Thamnocephalus platyurus by  Irina Blinova, Jukka Niskanen, Paula Kajankari, Liina Kanarbik, Aleksandr Käkinen, Heikki Tenhu, Olli-Pekka Penttinen, and Anne Kahru. Environmental Science and Pollution Research published November 11, 2012 online

The publisher offers an interesting option for this article. While it is behind a paywall, access is permitted through a temporary window if you want to preview a portion of the article that lies beyond the abstract.

Meanwhile here’s the article by the Duke researchers,

Low Concentrations of Silver Nanoparticles in Biosolids Cause Adverse Ecosystem Responses under Realistic Field Scenario by Benjamin P. Colman, Christina L. Arnaout, Sarah Anciaux, Claudia K. Gunsch, Michael F. Hochella Jr, Bojeong Kim, Gregory V. Lowry,  Bonnie M. McGill, Brian C. Reinsch, Curtis J. Richardson, Jason M. Unrine, Justin P. Wright, Liyan Yin, and Emily S. Bernhardt. PLoS ONE 2013; 8 (2): e57189 DOI: 10.1371/journal.pone.0057189

This article is open access as are all articles published by the Public Library of Science (PLoS) journals.

For anyone interested in the Duke University/CEINT mesocosm project, I made mention of it in an Aug. 15, 2011 posting.

Natural and engineered nanoparticles in an Orion magazine podcast & in a NanoBosc machinima piece

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The Jan. 16, 2013 Orion magazine podcast discussion (more about that later) regarding safety and engineered and natural nanoparticles arose from an article (worth reading) by Heather Millar in the magazine’s January/February 2013 issue, Pandora’s Boxes.

For anyone familiar with the term ‘Pandora’s box’, Millar’s and the magazine’s bias is made clear immediately, nanoparticles are small and threatening. From the Pandora’s box Wikipedia essay,

Today, the phrase “to open Pandora’s box” means to perform an action that may seem small or innocuous, but that turns out to have severe and far-reaching consequences. [emphases mine]

Millar’s article is well written and offers some excellent explanations. For example, there’s this from Pandora’s Boxes,

So chemistry and physics work differently if you’re a nanoparticle. You’re not as small as an atom or a molecule, but you’re also not even as big as a cell, so you’re definitely not of the macro world either. You exist in an undiscovered country somewhere between the molecular and the macroscopic. Here, the laws of the very small (quantum mechanics) merge quirkily with the laws of the very large (classical physics). Some say nanomaterials bring a third dimension to chemistry’s periodic table, because at the nano scale, long-established rules and groupings don’t necessarily hold up.

Then, she has some dodgier material,

Yet size seems to be a double-edged sword in the nanoverse. Because nanoparticles are so small, they can slip past the body’s various barriers: skin, the blood-brain barrier, the lining of the gut and airways. Once inside, these tiny particles can bind to many things. They seem to build up over time, especially in the brain. Some cause inflammation and cell damage. Preliminary research shows this can harm the organs of lab animals, though the results of some of these studies are a matter of debate.

Some published research has shown that inhaled nanoparticles actually become more toxic as they get smaller. Nano–titanium dioxide, one of the most commonly used nanoparticles (Pop-Tarts, sunblock), has been shown to damage DNA in animals and prematurely corrode metals. Carbon nanotubes seem to penetrate lungs even more deeply than asbestos. [emphases mine]

I think it’s worth ‘unpacking’ these two paragraphs, so here goes.  Slipping past the body’s barriers is a lot more difficult than Millar suggests in the first paragraph. My July 4, 2012 posting on breakthough research  where they penetrated the skin barrier includes this comment from me,

After all the concerns  about nanosunscreens and nanoparticles penetrating the skin raised by civil society groups, the Friends of the Earth in particular, it’s interesting to note that doctors and scientists consider penetration of the skin barrier to be extremely difficult. Of course, they seem to have solved [as of July 2012] that problem which means the chorus of concerns may rise to new heights.

I had a followup in my Oct.3, 2012 posting titled, Can nanoparticles pass through the skin or not?, suggesting there’s still a lot of confusion about this topic even within the scientific community.

Moving on to the other ‘breaches’. As I recall, there was a recent  (Autumn 2012?) nanomedicine research announcement that the blood-brain barrier was breached by nanoparticles. I haven’t yet encountered any mention of breaching the gut and I mention lungs in my next paragraph where I discuss carbon nanotubes.

As for that second paragraph, it’s an example of scaremongering. ‘Inhaled nanoparticles become more toxic as their size decreases’—ok. Why mention nano-titanium oxide in pop tarts and sunblocks, which are not inhaled, in the followup sentence? As for the reference to DNA damage and corroded metals further on, this is straight out of the Friends of the Earth literature which often cites research in a misleading fashion including those two pieces.  There is research supporting part of Millar’s statement about carbon nanotubes—provided they are long and multiwalled. In fact, as they get shorter, the resemblance to asbestos fibers in the lungs or elsewhere seems to disappear as per my Aug 22, 2012 posting and my Jan. 16, 2013 posting.

You don’t need to read the article before listening to the fascinating Jan. 16, 2013 Orion magazine podcast with Millar (reading portions of her article) and expert guests, Mark Wiesner from Duke University and director of their Center for Environmental Implications of Nano Technology (CEINT was first mentioned in my April 15, 2011 posting), Ronald Sandler from Northeastern University and author of Nanotechnology: The Social And Ethical Issues, and Jaydee Hanson, policy director for the International Center for Technology Assessment.

The discussion between Wiesner, Sandler, and Hanson about engineered and natural nanoparticles is why I’ve called the podcast fascinating. Hearing these experts ‘fence’ with each other highlights the complexities and subtleties inherent in discussions about emerging technologies (nano or other) and risk. Millar did not participate in that aspect of the conversation and I imagine that’s due to the fact that she has only been researching this area for six months while the other speakers all have several years worth experience individually and, I suspect, may have debated each other previously.

At the risk of enthusing too much about naturally occurring nanoparticles, I’m mentioning, again (my Feb. 1, 2013 posting), the recently published book by Nanowiki, Nanoparticles Before Nanotechnology, in the context of the stunning visual images used to illustrate the book. I commented previously about them and Victor Puntes of the Inorganic Nanoparticles Group at the Catalan Institute of Nanotechnology (ICN) and one of the creators of this imagery, kindly directed me to a machinima piece (derived from the NanoBosc Second Life community) which is the source for the imagery. Here it is,

NanoBosc from Per4mance MetaLES ..O.. on Vimeo.

Happy Weekend!

Mesocosms and nanoparticles at Duke University

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It’s that time of year when just about everybody seems to be on holidays and finding material to post about becomes harder than usual.  Consequently, I dug through some of my backfiles to find this piece on mesocosms and Duke University from November 2010.

From the article, Ecosystem experiments to assess the environmental impact of nanoparticles, by Whitney J. Howell published November 25, 2010 on Nanowerk,

Deep inside Duke Forest, 32 alternate universes sit in quiet rows. They look identical – each with a puddle, some land, a few plants.

But wholly imperceptible to the naked eye, these plots have distinct and important differences.

The realms, known as mesocosms, house individual types of nanoparticles as part of a research effort conducted by the Center for the Environmental Implications of Nano Technology (CEINT) based at Duke University.

The mesocosms are (from the CEINT Mesocosm Construction page) “3ft x 12ft [constructed environments] where researchers can add nanoparticles [to study interactions] and effects on plants, fish, bacteria, and other elements within these contained systems.”

Mesocosm prototypes at Duke University (downloaded from Nanowerk)

According to Howell’s article (originally published in the Raleigh News & Observer), the mesocosm project at Duke should be winding up shortly,

To track where and at what levels the environment absorbs nanoparticles, CEINT began the yearlong mesocosm project in August [2011]. The findings will also reveal the effects of nanoparticle presence.

Each waist-high, 3-foot-by-12-foot box contains nanoparticles coated with a different substance, such as titanium dioxide or silver. By following the coating’s trail through the mesocosm, Wiesner said, researchers can pinpoint how the nanoparticles either positively or negatively alter their surroundings and at what levels they might become toxic.

For example, nanosilver has anti-microbial properties and could be a powerful disinfectant. But if high concentrations of the particles wipe out all surrounding bacteria and viruses – even those that may be benign or beneficial – the effects on plants and animals is unknown.

The Duke investigators are monitoring the mesocosm changes as nanosilver and other nanoparticle levels increase, hoping to identify which substances are most harmful to the environment and humans, and at what level they become worrisome.

CEINT’s external advisory board features Dr. Andrew Maynard, Director of the University of Michigan Risk Science Center (and mentioned here fairly frequently due to his longstanding expertise on nanotechnology [he was formerly the Chief Science Advisor for the Project on Emerging Nanotechnologies based in Washington, DC]).

They’ve been busy at the CEINT, here’s where you can find a list of publications by the staff, including blockbusters such as,

Shoults-Wilson, WA, Zhurbich OI, McNear DH, Tsyusko OV, Bertsch PM, Unrine JM.  2011.  Evidence for avoidance of Ag [silver] nanoparticles by earthworms (Eisenia fetida). Ecotoxicology. 20:385-96. Abstract

And

Chae, SR, Hotze EM, Xiao Y, Rose J, Wiesner MR.  2010.  Comparison of Methods for Fullerene Detection and Measurements of Reactive Oxygen Production in Cosmetic Products. Environmental Engineering Science. 27:797-804. Abstract

You can find more of Whitney Howell’s work here.