Tag Archives: silver nanoparticles

Danish scientists provide insights into celllular response to silver nanoparticles

The conclusions are concerning but the scientists at the University of Southern Denmark are careful to note that this research on silver nanopartices was performed in a laboratory setting which does not necessarily predict what might happen under real life conditions.

As for the research itself, a Feb. 28, 2014 news item on Azonano has this to say,

Endocrine disrupters are not the only worrying chemicals that ordinary consumers are exposed to in everyday life. Also nanoparticles of silver, found in e.g. dietary supplements, cosmetics and food packaging, now worry scientists. A new study from the University of Southern Denmark shows that nano-silver can penetrate our cells and cause damage.

Silver has an antibacterial effect and therefore the food and cosmetic industry often coat their products with silver nanoparticles. Nano-silver can be found in e.g. drinking bottles, cosmetics, band aids, toothbrushes, running socks, refrigerators, washing machines and food packagings.

“Silver as a metal does not pose any danger, but when you break it down to nano-sizes, the particles become small enough to penetrate a cell wall. If nano-silver enters a human cell, it can cause changes in the cell”, explain Associate Professor Frank Kjeldsen and PhD Thiago Verano-Braga, Department of Biochemistry and Molecular Biology at the University of Southern Denmark.

A Feb. 27, 2014 University of Southern Denmark news release, which originated the news item, provides more detail about the research,

The researchers examined human intestinal cells, as they consider these to be most likely to come into contact with nano-silver, ingested with food.

“We can confirm that nano-silver leads to the formation of harmful, so called free radicals in cells. We can also see that there are changes in the form and amount of proteins. This worries us”, say Frank Kjeldsen and Thiago Verano-Braga.

A large number of serious diseases are characterized by the fact that there is an overproduction of free radicals in cells. This applies to cancer and neurological diseases such as Alzheimer’s and Parkinson’s.

Kjeldsen and Verano-Braga emphasizes that their research is conducted on human cells in a laboratory, not based on living people. They also point out that they do not know how large a dose of nano-silver, a person must be exposed to for the emergence of cellular changes.

“We don’t know how much is needed, so we cannot conclude that nano-silver can make you sick. But we can say that we must be very cautious and worried when we see an overproduction of free radicals in human cells”, they say.

Nano-silver is also sold as a dietary supplement, promising to have an antibacterial, anti-flu and cancer-inhibatory effect. The nano-silver should also help against low blood counts and bad skin. In the EU, the marketing of dietary supplements and foods with claims to have medical effects is not allowed. But the nano-silver is easy to find and buy online.

In the wake of the SDU-research, the Danish Veterinary and Food Administration now warns against taking dietary supplements with nano-silver.

“The recent research strongly suggests that it can be dangerous”, says Søren Langkilde from the Danish Veterinary and Food Administration to the Danish Broadcasting Corporation (DR).

The researchers supplied this image to illustrate the abstract for their paper (link and citation to follow),

Courtesy University of Southern Denmark

Courtesy University of Southern Denmark

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

Insights into the Cellular Response Triggered by Silver Nanoparticles Using Quantitative Proteomics by Thiago Verano-Braga, Rona Miethling-Graff, Katarzyna Wojdyla, Adelina Rogowska-Wrzesinska, Jonathan R. Brewer, Helmut Erdmann, and Frank Kjeldsen. ACS Nano, Article ASAP DOI: 10.1021/nn4050744 Publication Date (Web): February 10, 2014
Copyright © 2014 American Chemical Society

This paper is behind a paywall.

Silver ions in the environment

Earlier this week (Feb. 24, 2014), I published a post featuring Dr. Andrew Maynard, Director of the University of Michigan’s Risk Science Center in an introductory video describing seven surprising facts about silver nanoparticles. For those who want to delve more deeply, there’s a Feb. 25, 2014 news item on Nanowerk describing some Swiss research into silver nanoparticles and ions in aquatic environments,

It has long been known that, in the form of free ions, silver particles can be highly toxic to aquatic organisms. Yet to this day, there is a lack of detailed knowledge about the doses required to trigger a response and how the organisms deal with this kind of stress. To learn more about the cellular processes that occur in the cells, scientists from the Aquatic Research Institute, Eawag [Swiss Federal Institute of Aquatic Science and Technology], subjected algae to a range of silver concentrations.

In the past, silver mostly found its way into the environment in the vicinity of silver mines or via wastewater [emphasis mine] emanating from the photo industry. More recently, silver nanoparticles have become commonplace in many applications – as ingredients in cosmetics, food packaging, disinfectants, and functional clothing. Though a recent study conducted by the Swiss National Science Foundation revealed that the bulk of silver nanoparticles is retained in wastewater treatment plants, only little is known about the persistence and the impact of the residual nano-silver in the environment.

The Feb. 25, 2014 Eawag media release, which originated the news item, describes the research in further detail,

Smitha Pillai from the Eawag Department of Environmental Toxicology and her colleagues from EPF Lausanne and ETH Zürich studied the impact of various concentrations of waterborne silver ions on the cells of the green algae Chlamydomonas reinhardtii. Silver is chemically very similar to copper, an essential metal due to its importance in several enzymes. Because of that, silver can exploit the cells’ copper transport mechanisms and sneak into them undercover. This explains why, already after a short time, concentrations of silver in the intracellular fluid can reach up to one thousand times those in the surrounding environment.

A prompt response

Because silver damages key enzymes involved in energy metabolism, even low concentrations can cut photosynthesis and growth rates by a half in just 15 minutes. Over the same time period, the researchers also detected changes in the activity of about 1000 other genes and proteins, which they interpreted as a response to the stressor – an attempt to repair silver-induced damage. At low concentrations, the cells’ photosynthesis apparatus recovered within five hours, and recovery mechanisms were sufficient to deal with all but the highest concentrations tested.

A number of unanswered questions

At first glance, the results are reassuring because the silver concentrations that the algae are subject to in the environment are rarely as high as those applied in the lab, which allows them to recover quickly – at least externally. But the experiments also showed that even low silver concentrations have a significant effect on intracellular processes and that the algae divert their energy to repairing damage incurred. This can pose a problem when other stressors act in parallel, such as increased UV-radiation or other chemical compounds. Moreover, it remains unknown to this day whether the cells have an active mechanism to shuttle out the silver. Lacking such a mechanism, the silver could have adverse effects on higher organisms, given that algae are at the bottom of the food chain.

You can find the researchers’ paper here,

Linking toxicity and adaptive responses across the transcriptome, proteome, and phenotype of Chlamydomonas reinhardtii exposed to silver by Smitha Pillai, Renata Behra, Holger Nestler, Marc J.-F. Suter, Laura Sigg, and Kristin Schirmer. Proceedings of the National Academy of Sciences (PNAS) – early edition 18.February 2014, www.pnas.org/cgi/doi/10.1073/pnas.1319388111

The paper is available through the PNAS open access option.

I have published a number of pieces about aquatic enviornments and wastewater and nanotechnology-enabled products as useful for remediation efforts and as a source of pollution. Here’s a Feb. 28, 2013 posting where I contrasted two pieces of research on silver nanoparticles. The first was research in an aquatic environment and the other concerned wastewater.

Tracking gas, oil, and, possibly, water in wells

A Feb. 24, 2014 Rice University news release (also on EurekAlert) and on Azonano as a Feb. 25, 2014 news item) describes a technique tracks which wells are producing oil or gas in fracking operations,

A tabletop device invented at Rice University can tell how efficiently a nanoparticle would travel through a well and may provide a wealth of information for oil and gas producers.

The device gathers data on how tracers – microscopic particles that can be pumped into and recovered from wells – move through deep rock formations that have been opened by hydraulic fracturing [fracking].

Here’s an image of two Rice scientists playing around with a prototype of their tabletop device,

Rice University chemist Andrew Barron and graduate student Brittany Oliva-Chatelain investigate the prototype of a device that allows for rapid testing of nanotracers for the evaluation of wells subject to hydraulic fracturing. (Credit: Jeff Fitlow/Rice University)

Rice University chemist Andrew Barron and graduate student Brittany Oliva-Chatelain investigate the prototype of a device that allows for rapid testing of nanotracers for the evaluation of wells subject to hydraulic fracturing. (Credit: Jeff Fitlow/Rice University)

The news release goes on to describe the fracking process and explain why the companies don’t know which well is actually producing (Note: Links have been removed),

Drilling companies use fracturing to pump oil and gas from previously unreachable reservoirs. Fluids are pumped into a wellbore under high pressure to fracture rocks, and materials called “proppants,” like sand or ceramic, hold the fractures open. “They’re basically making a crack in the rock and filling it with little beads,” said Rice chemist Andrew Barron, whose lab produced the device detailed in the Royal Society of Chemistry journal Environmental Science Processes and Impacts.

But the companies struggle to know which insertion wells — where fluids are pumped in — are connected to the production wells where oil and gas are pumped out. “They may be pumping down three wells and producing from six, but they have very little idea of which well is connected to which,” he said.

Tracer or sensor particles added to fracturing fluids help solve that problem, but there’s plenty of room for optimization, especially in minimizing the volume of nanoparticles used now, he said. “Ideally, we would take a very small amount of a particle that does not interact with proppant, rock or the gunk that’s been pumped downhole, inject it in one well and collect it at the production well. The time it takes to go from one to the other will tell you about the connectivity underground.”

Barron explained the proppant itself accounts for most of the surface area the nanoparticles encounter, so it’s important to tune the tracers to the type of proppant used.

He said the industry lacks a uniform method to test and optimize custom-designed nanoparticles for particular formations and fluids. The ultimate goal  is to optimize the particles so they don’t clump together or stick to the rock or proppant and can be reliably identified when they exit the production well.

Here’s how the tracers work (from the news release),

The automated device by Barron, Rice alumnus Samuel Maguire-Boyle and their colleagues allows them to run nanotracers through a small model of a geological formation and quickly analyze what comes out the other side.

The device sends a tiny amount of silver nanoparticle tracers in rapid pulses through a solid column, simulating the much longer path the particles would travel in a well. That gives the researchers an accurate look at both how sticky and how robust the particles are.

“We chose silver nanoparticles for their plasmon resonance,” Barron said. “They’re very easy to see (with a spectroscope) making for high-quality data.” He said silver nanoparticles would be impractical in a real well, but because they’re easy to modify with other useful chemicals, they are good models for custom nanoparticles.

“The process is simple enough that our undergraduates make different nanoparticles and very quickly test them to find out how they behave,” Barron said.

The method also shows promise for tracking water from source to destination, which could be valuable for government agencies that want to understand how aquifers are linked or want to trace the flow of elements like pollutants in a water supply, he said.

Barron said the Rice lab won’t oversee production of the test rig, but it doesn’t have to. “We just published the paper, but if companies want to make their own, it includes the instructions. The supplementary material is basically a manual for how to do this,” he said.

You can find the paper with this link and/or citation,

Automated method for determining the flow of surface functionalized nanoparticles through a hydraulically fractured mineral formation using plasmonic silver nanoparticles by Samuel J. Maguire-Boyle, David J. Garner, Jessica E. Heimann, Lucy Gao, Alvin W. Orbaek, and Andrew R. Barron. Environ. Sci.: Processes Impacts, 2014,16, 220-231 DOI: 10.1039/C3EM00718A First published online 07 Jan 2014

This paper has been published in one of the Royal Society’s open access journals.

My final note, one of my more recent posts about fracking highlights some research that was taking place in Texas (Rice University’s home state) at Texas A&M University, see my July 29, 2013 posting.

Surprising facts about silver nanoparticles from the University of Michigan

Dr. Andrew Maynard, Director of the University of Michigan’s Risk Science Center, has featured seven surprising facts about silver nanoparticles in his latest video in the Risk Bites series. Before getting to the video,here’s an introduction to the topic of silver nanoparticles from a Feb. 18, 2014 posting by Ishani Hewage on the University of Michigan’s Risk Sense blog (Note: A link has been removed),

Silver – known for its germ-killing capabilities – has been used for thousands of years. In recent times though, concerns have been raised over the potential health and environmental risks associated with one particular form of silver that has been used increasingly in a range of products: engineered silver nanoparticle. In this week’s Risk Bites, Andrew Maynard, director of the Risk Science Center, rounds-up seven aspects of silver nanoparticles that might help you weigh up their risks and benefits.

“Silver has long been used for its medicinal properties,” says Andrew. “People used to intentionally dose themselves with silver nanoparticles in the form a silver laced tonic as a cure-all.”

Nowadays, the use of silver nanoparticles is not just limited to the medical field. The military, athletes and manufactures are increasingly using them to develop smart new technologies that inhibit bacterial growth and enhance overall performance.  These microscopically small particles make it easier to get silver into products without compromising them …

Without more ado, here’s the video, ’7 surprising facts about silver nanoparticles and health’:

Both the blog posting and this link will lead you to more information about silver nanoparticles.

Food and nanotechnology (as per Popular Mechanics) and zinc oxide nanoparticles in soil (as per North Dakota State University)

I wouldn’t expect to find an article about food in a magazine titled Popular Mechanics but there it is, a Feb. 19,2014 article by Christina Ortiz (Note: A link has been removed),

For a little more than a decade, the food industry has been using nanotechnology to change the way we grow and maintain our food. The grocery chain Albertsons currently has a list of nanotech-touched foods in its home brand, ranging from cookies to cheese blends.

Nanotechnology use in food has real advantages: The technology gives producers the power to control how food looks, tastes, and even how long it lasts.

Looks Good and Good for You?

The most commonly used nanoparticle in foods is titanium dioxide. It’s used to make foods such as yogurt and coconut flakes look as white as possible, provide opacity to other food colorings, and prevent ingredients from caking up. Nanotech isn’t just about aesthetics, however. The biggest potential use for this method involves improving the nutritional value of foods.

Nano additives can enhance or prevent the absorption of certain nutrients. In an email interview with Popular Mechanics, Jonathan Brown, a research fellow at the University of Minnesota, says this method could be used to make mayonnaise less fattening by replacing fat molecules with water droplets.

I did check out US grocer, Albertson’s list of ‘nanofoods’, which they provide and discovered that it’s an undated listing on the Project of Emerging Nanotechnologies’ Consumer Products Inventory (CPI). The inventory has been revived recently after lying moribund for a few years (my Oct. 28, 2013 posting describes the fall and rise) and I believe that this 2013 CPI incarnation includes some oversight and analysis of the claims made, which the earlier version did not include. Given that the Albertson’s list is undated it’s difficult to assess the accuracy of the claims regarding the foodstuffs.

If you haven’t read about nanotechnology and food before, the Ortiz article provides a relatively even-handed primer although it does end on a cautionary note. In any event, it was interesting to get a bit of information about the process of ‘nanofood’ regulation in the US and other jurisdictions (from the Ortiz article),

Aside from requiring manufacturers to provide proof that nanotechnology foods are safe, the FDA has yet to implement specific testing of its own. But many countries are researching ways to balance innovation and regulation in this market. In 2012 the European Food Safety Authority (EFSA) released an annual risk assessment report outlining how the European Union is addressing the issue of nanotech in food. In Canada the Food Directorate “is taking a case-by-case approach to the safety assessment of food products containing or using nanomaterials.”

I featured the FDA’s efforts regarding regulation and ‘nanofood’ in an April 23, 2012 posting,

It looks to me like this [FDA's draft guidance for 'nanofoods'] is an attempt to develop a relationship where the industry players in the food industry to police their nanotechnology initiatives with the onus being on industry to communicate with the regulators in a continuous process, if not at the research stage certainly at the production stage.

At least one of the primary issues with any emerging technology revolves around the question of risk. Do we stop all manufacturing and development of nanotechnology-enabled food products until we’ve done the research? That question assumes that taking any risks is not worth the currently perceived benefits. The corresponding question, do we move forward and hope for the best? does get expressed perhaps not quite so baldly; I have seen material which suggests that research into risks needlessly hampers progress.

After reading on this topic for five or so years, my sense is that most people are prepared to combine the two approaches, i.e., move forward while researching possible risks. The actual conflicts seem to centre around these questions, how quickly do we move forward; how much research do we need; and what is an acceptable level of risk?

On the topic of researching the impact that nanoparticles might have on plants (food or otherwise), a January 24, 2013 North Dakota State University (NDSU) news release highlights a student researcher’s work on soil, plants, and zinc oxide nanoparticles,

NDSU senior Hannah Passolt is working on a project that is venturing into a very young field of research. The study about how crops’ roots absorb a microscopic nutrient might be described as being ahead of the cutting-edge.

In a laboratory of NDSU’s Wet Ecosystem Research Group, in collaboration with plant sciences, Passolt is exploring how two varieties of wheat take up extremely tiny pieces of zinc, called nanoparticles, from the soil.

As a point of reference, the particles Passolt is examining are measured at below 30 nanometers. A nanometer is 1 billionth of a meter.

“It’s the mystery of nanoparticles that is fascinating to me,” explained the zoology major from Fargo. “The behavior of nanoparticles in the environment is largely unknown as it is a very new, exciting science. This type of project has never been done before.”

In Passolt’s research project, plants supplied by NDSU wheat breeders are grown in a hydroponic solution, with different amounts of zinc oxide nanoparticles introduced into the solution.

Compared to naturally occurring zinc, engineered zinc nanoparticles can have very different properties. They can be highly reactive, meaning they can injure cells and tissues, and may cause genetic damage. The plants are carefully observed for any changes in growth rate and appearance. When the plants are harvested, researchers will analyze them for actual zinc content.

“Zinc is essential for a plant’s development. However, in excess, it can be harmful,” Passolt said. “In one of my experiments, we are using low and high levels of zinc, and the high concentrations are showing detrimental effects. However, we will have to analyze the plants for zinc concentrations to see if there have been any effects from the zinc nanoparticles.”

Passolt has conducted undergraduate research with the Wet Ecosystem Research Group for the past two years. She said working side-by-side with Donna Jacob, research assistant professor of biological sciences; Marinus Otte; professor of biological sciences; and Mohamed Mergoum, professor of plant sciences, has proven to be challenging, invigorating and rewarding.

“I’ve gained an incredible skill set – my research experience has built upon itself. I’ve gotten to the point where I have a pretty big role in an important study. To me, that is invaluable,” Passolt said. “To put effort into something that goes for the greater good of science is a very important lesson to learn.”

According to Jacob, Passolt volunteered two years ago, and she has since become an important member of the group. She has assisted graduate students and worked on her own small project, the results of which she presented at regional and international scientific conferences. “We offered her this large, complex experiment, and she’s really taken charge,” Jacob said, noting Passolt assisted with the project’s design, handled care of the plants and applied the treatments. When the project is completed, Passolt will publish a peer-reviewed scientific article.

“There is nothing like working on your own experiment to fully understand science,” Jacob said. “Since coming to NDSU in 2006, the Wet Ecosystem Research Group has worked with more than 50 undergraduates, possible only because of significant support from the North Dakota IDeA Networks of Biomedical Research Excellence program, known as INBRE, of the NIH National Center for Research Resources.”

Jacob said seven undergraduate students from the lab have worked on their own research projects and presented their work at conferences. Two articles, so far, have been published by undergraduate co-authors. “I believe the students gain valuable experience and an understanding of what scientists really do during fieldwork and in the laboratory,” Jacob said. “They see it is vastly different from book learning, and that scientists use creativity and ingenuity daily. I hope they come away from their experience with some excitement about research, in addition to a better resume.”

Passolt anticipates the results of her work could be used in a broader view of our ecosystem. She notes zinc nanoparticles are an often-used ingredient in such products as lotions, sunscreens and certain drug delivery systems. “Zinc nanoparticles are being introduced into the environment,” she said. “It gets to plants at some point, so we want to see if zinc nanoparticles have a positive or negative effect, or no effect at all.”

Researching nanoparticles the effects they might have on the environment and on health is a complex process as there are many types of nanoparticles some of which have been engineered and some of which occur naturally, silver nanoparticles being a prime example of both engineered and naturally occurring nanoparticles. (As well, the risks may lie more with interactions between nanomaterials.) For an example of research, which seems similar to the NDSU effort, there’s this open access research article,

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

One last comment, the Wet Ecosystem Research Group (WERG) mentioned in the news release about Passolt has an interesting history (from the homepage; Note: Links have been removed),

Marinus Otte and Donna Jacob brought WERG to the Department of Biological Sciences in the Fall of 2006.  Prior to that, the research group had been going strong at University College Dublin, Ireland, since 1992.

The aims for the research group are to train graduate and undergraduate students in scientific research, particularly wetlands, plants, biogeochemistry, watershed ecology and metals in the environment.  WERG research  covers a wide range of scales, from microscopic (e.g. biogeochemical processes in the rhizosphere of plants) to landscape (e.g. chemical and ecological connectivity between prairie potholes across North Dakota).  Regardless of the scale, the central theme is biogeochemistry and the interactions between multiple elements in wet environments.

The group works to collaborate with a variety of researchers, including soil scientists, geologists, environmental engineers, microbiologists, as well as with groups underpinning management of natural resources, such the Minnesota Department of Natural Resources, the Department of Natural Resources of Red Lake Indian Reservation, and the North Dakota Department of Health, Division of Water Quality.

Currently, WERG has several projects, mostly in North Dakota and Minnesota.  Otte and Jacob are also Co-directors of the North Dakota INBRE Metal Analysis Core, providing laboratory facilities and mentoring for researchers in undergraduate colleges throughout the state. Otte and Jacob are also members of the Upper Midwest Aerospace Consortium.

Lab tests show silver nanoparticles in cream blocks HIV entry for up to 72 hours

Since at least 2005 (the article reference will be given later in this posting), researchers have been aware that silver nanoparticles can block the HIV virus from entering a cell. The latest work in this area has resulted in a vaginal cream laced with silver nanoparticles according to a Jan. 28, 2014 news item on ScienceDaily,

Lara Villegas [Humberto Lara Villegas, specialist in nanoparticles and virology from the University of Monterrey, Mexico (UDEM)] explained that HIV makes its entry to immune cells (CD4) of the organism with the aid of a protein known as GP120, which allows the virus adherence to the cells. This same principle is used by silver nanoparticles to attach themselves to this protein and block it, turning the virus inactive.

The Mexican researcher informed that the cream has been tested in samples of human tissue and has proven the efficiency of silver nanoparticles to avoid the transmission of the virus through cervical mucous membrane.

The Jan. 28, 2014 Investigación y Desarrollo news release (on the Alpha Gallileo website), which originated the news item, provides additional details from Lara Villegas’ perspective,

The researcher from UDEM, who has worked in Israel and The United States, assured that after applied, the cream starts to work in less than a minute, and has an effective protection of up to 72 hours.

Given that the function of this product is the inactivation of the virus, although this is a vaginal cream, will also protect the sexual partner.

“Normally – he highlighted-, the medication used against the virus act within the cell to avoid its replication. This is a very different case, given that the nanoparticle goes directly against the HIV and no longer allows its entry to the cell”.

So far, no toxicity of the silver nanoparticles has been reported, although he added that research is yet to be performed to evaluate the possible side effects of silver properties.

“Right now, I am certain that this microbicide is going to avoid the virus entering the organism, but I cannot yet assure that is totally harmless, because the clinical trials are a long and expensive process”, the researched added.

He exposed that the use of gels are usually accompanied by irritation, which favors the entry of the virus, which is why the cream was enriched with an anti-inflammatory effect.

Currently, with the obtained results, researchers will proceed to perform experimentation in mice that accept human cells, to later begin with human clinical trials.

He added that this cream could prevent the transmition of other sexually acquired virus like the Human Papilloma Virus (HPV). Likewise, he considered that silver nanoparticles could be used to combat bacteria transmitted the same way.

As promised here’s a citation for and a link to the 2005 paper; I haven’t found any references in my admittedly brief search for a paper about this latest work,,

Interaction of silver nanoparticles with HIV-1 by Jose Luis Elechiguerra, Justin L Burt, Jose R Morones, Alejandra Camacho-Bragado, Xiaoxia Gao, Humberto H Lara, and Miguel Jose Yacaman. Journal of Nanobiotechnology 2005, 3:6  doi:10.1186/1477-3155-3-6

This paper is open access.

Here’s  the Investigación y Desarrollo website which seems to act as a hub for research in Mexico. Note: You will need Spanish language skills to fully utilize this site.

Get yourself some e-whiskers for improved tactile sensing

E-whiskers are highly responsive tactile sensor networks made from carbon nanotubes and silver nanoparticles that resemble the whiskers of cats and other mammals. Courtesy: Berkeley Labs [downloaded from http://newscenter.lbl.gov/science-shorts/2014/01/20/e-whiskers/]

E-whiskers are highly responsive tactile sensor networks made from carbon nanotubes and silver nanoparticles that resemble the whiskers of cats and other mammals. Courtesy: Berkeley Labs [downloaded from http://newscenter.lbl.gov/science-shorts/2014/01/20/e-whiskers/]

A Jan. 21, 2014 news item on Azonano features work from researchers who have simulated the sensitivity of cat’s and rat’s whiskers by creating e-whiskers,

Researchers with Berkeley Lab and the University of California (UC) Berkeley have created tactile sensors from composite films of carbon nanotubes and silver nanoparticles similar to the highly sensitive whiskers of cats and rats. These new e-whiskers respond to pressure as slight as a single Pascal, about the pressure exerted on a table surface by a dollar bill. Among their many potential applications is giving robots new abilities to “see” and “feel” their surrounding environment.

The Jan. 20, 2014 Lawrence Berkeley National Laboratory (Berkeley Lab) ‘science short’ by Lynn Yarris, which originated the news item,  provides more information about the research,

“Whiskers are hair-like tactile sensors used by certain mammals and insects to monitor wind and navigate around obstacles in tight spaces,” says the leader of this research Ali Javey, a faculty scientist in Berkeley Lab’s Materials Sciences Division and a UC Berkeley professor of electrical engineering and computer science.  “Our electronic whiskers consist of high-aspect-ratio elastic fibers coated with conductive composite films of nanotubes and nanoparticles. In tests, these whiskers were 10 times more sensitive to pressure than all previously reported capacitive or resistive pressure sensors.”

Javey and his research group have been leaders in the development of e-skin and other flexible electronic devices that can interface with the environment. In this latest effort, they used a carbon nanotube paste to form an electrically conductive network matrix with excellent bendability. To this carbon nanotube matrix they loaded a thin film of silver nanoparticles that endowed the matrix with high sensitivity to mechanical strain.

“The strain sensitivity and electrical resistivity of our composite film is readily tuned by changing the composition ratio of the carbon nanotubes and the silver nanoparticles,” Javey says. “The composite can then be painted or printed onto high-aspect-ratio elastic fibers to form e-whiskers that can be integrated with different user-interactive systems.”

Javey notes that the use of elastic fibers with a small spring constant as the structural component of the whiskers provides large deflection and therefore high strain in response to the smallest applied pressures. As proof-of-concept, he and his research group successfully used their e-whiskers to demonstrate highly accurate 2D and 3D mapping of wind flow. In the future, e-whiskers could be used to mediate tactile sensing for the spatial mapping of nearby objects, and could also lead to wearable sensors for measuring heartbeat and pulse rate.

“Our e-whiskers represent a new type of highly responsive tactile sensor networks for real time monitoring of environmental effects,” Javey says. “The ease of fabrication, light weight and excellent performance of our e-whiskers should have a wide range of applications for advanced robotics, human-machine user interfaces, and biological applications.”

The researchers’ paper has been published in the Proceedings of the National Academy of Sciences and is titled: “Highly sensitive electronic whiskers based on patterned carbon nanotube and silver nanoparticle composite films.”

Here’s what the e-whiskers look like,

An array of seven vertically placed e-whiskers was used for 3D mapping of the wind by Ali Javey and his group [ Kuniharu Takei, Zhibin Yu, Maxwell Zheng, Hiroki Ota and Toshitake Takahashi].  Courtesy: Berkeley Lab

An array of seven vertically placed e-whiskers was used for 3D mapping of the wind by Ali Javey and his group [ Kuniharu Takei, Zhibin Yu, Maxwell Zheng, Hiroki Ota and Toshitake Takahashi]. Courtesy: Berkeley Lab

Crypton and NANO-TEX together at last

A Jan. 6, 2014 news item on Nanowerk notes that Crypton Fabrics has purchased NANO-TEX,

CRYPTON INC. has acquired NANO-TEX®, announced Randy Rubin, Chairman of The Crypton Companies. The privately held, 20-year-old Crypton Fabrics, based in Bloomfield Hills, Michigan, recently purchased NANO-TEX from private equity and venture capital investors; WL Ross and Co. LLC as major stockholders, in addition to Norwest Venture Partners, Masters Capital Nanotechnology Fund, Firelake Capital Management and Masters Capital Management.

NANO-TEX is a textile technology company whose performance finishes have enhanced leading consumer brands such as GAP, TARGET, MAIDENFORM, BASS PRO SHOPS, NORDSTROM, LAND’S END, FISHER-PRICE and many more.

The Jan. 6, 2014 Crypton (there has to be a Superman or inert gas enthusiast in that company) press release, which can be found on this page under this title: Silicon Valley to Motown, Performance Textile Leader Crypton Purchases Nano-Tex, explains why the NANO-TEX acquisition was so attractive and what it means to NANO-TEX’s major stockholders,

NANO‐TEX employs a proprietary nanotechnology approach to enhance textiles at the molecular level that provides permanent performance attributes such as stain and water resistance, moisture wicking, odor control, static elimination and wrinkle free properties. The end result is performance fabrics that maintain the original comfort, look and feel of the fabric and perform for the life of the product.

In 2013, NANO‐TEX technologies were on $280 million in branded finished products at retail worldwide.

Wilbur Ross, Jr., Chairman of WL Ross said, “We are extremely pleased by Crypton’s acquisition. This assures that NANO‐TEX will continue on a strong growth trajectory. Its expanding market reach and prominence will further enhance the competitiveness of WL Ross’s companies in the consumer and industrial fabrics industries, too; the goal that sparked our initial investment interest in NANO‐TEX eight years ago.”

It seems there was a specific product which attracted the Crypton team’s attention,

“This is a strategic acquisition as we extend our market share with apparel throughout the world. The intellectual properties and latest development, Aquapel®, a non‐fluorinated repellency treatment, is very exciting to our research team,” said Rubin.

There’s more about this product on the NANO-TEX Aquapel® page.

On a completely other note, at least one NANO-TEX product has silver in it according to a 2007 entry on the Consumer Products Inventory (Project on Emerging Nanotechnologies),

They Say:

“Nano-Tex™’s revolutionary technology fundamentally transforms fabric at the nano-level to dramatically improve your favorite everyday clothing.”

Nanomaterials:

Silver

Potential Exposure Pathways:

Dermal

How much we know:

Category 4 (Unsupported claim)

Additional Information:

Generic Product

Crypton too has silver in at least one product (from the INCASE Fabric Protection FAQs),

Q:  How does INCASE™ resist bacterial growth?
A: Silver Ion technology is used in INCASE to inhibit the growth of a broad spectrum of medically relevant microorganisms, including bacteria. Silver is one of nature’s original antimicrobials. Used thousands of years ago by Greeks in vessels to preserve water and wine, the natural benefits of silver have now been tapped to keep fabrics odor-free.

Cyrpton’s INCASE product uses sliver ions, which according to some research at Rice University (based in Texas, US), are more toxic than silver nanoparticles, from my July 13, 2012 posting,

He [Pedro Alvarez, George R. Brown Professor and chair of Rice’s Civil and Environmental Engineering Department] said the finding should shift the debate over the size, shape and coating of silver nanoparticles. [emphasis mine] “Of course they matter,” Alvarez said, “but only indirectly, as far as these variables affect the dissolution rate of the ions. The key determinant of toxicity is the silver ions. So the focus should be on mass-transfer processes and controlled-release mechanisms.”

Crypton’s About page strongly suggests an environmentally friendly and health conscious company (Note: Links have been removed),

Innovation. Industry leadership. A deep commitment to product excellence. These core elements are at the heart of the Crypton DNA – a labor of love that began in 1993 when founders Craig and Randy Rubin set out to create a new generation of stylish fabrics that were moisture-resistant and easy-to-clean, yet soft, comfortable and breathable.

From the basement of their Michigan home, a textile revolution was born.

Now based in West Bloomfield Michigan, with a green manufacturing facility in Kings Mountain, North Carolina, Crypton is the only textile solution in the world offering complete stain, moisture, mildew, bacteria and odor-resistant protection thanks to a patented process developed by some of the leading minds in the textile industry.

Early on, by offering a fabric – not a vinyl or plastic – that was capable of resisting stains, moisture, odors and bacteria, Crypton proved to be the perfect solution for the health care market. Following this initial success, Crypton solutions rapidly expanded into some of the finest restaurants, hotels, cruise ships around the world, as well as government complexes, schools and health care facilities.

Now trusted and relied on by over 90% of contract designers, there are more than 20,000 patterns of Crypton fabric available today. Crypton is the only fabric deemed a non-porous surface and can be disinfected when used in conjunction with our U.S. EPA-approved Crypton Disinfectant & Deodorizer.

From fabric, carpet, leather, wall and mattress to pet beds, home accessories, bags and luggage – our mission is to give customers more ways to live healthy, live beautifully and Live Clean®.

While there is no incontrovertible proof that silver nanoparticles and/or silver ions are a serious threat to the environment, it would be nice to see companies acknowledge some of the concerns.

Finding out how silver escapes from tristructural-isotopic (TRISO) fuel particles

South African-born and Idaho-based researcher Isabella van Rooyen has solved a problem of longstanding interest to nuclear researchers according to a Jan. 3, 2014 news item on Nanowerk,

Some come to Idaho to travel the highways that lead to the Tetons, to Yellowstone, to small towns and big adventures. Idaho National Laboratory researcher Isabella van Rooyen came, all the way from South Africa, looking for a piece of silver 500,000 times smaller than a poppy seed.

The silver was somewhere inside irradiated tristructural-isotopic (TRISO) fuel particles — a safer, more efficient, next-generation nuclear fuel — the “poppy seed” in question. Break a TRISO fuel particle open and it looks like a jaw breaker on the inside. An outer shell of carbon coats a layer of silicon carbide, which coats the uranium center where the energy-releasing fission happens. These layers are meant to contain the radioactive products of fission, which includes little bits of silver. Containment of the radioactive material is built right into the fuel itself.

But it doesn’t always work perfectly. Occasionally, in just one or two out of 100 particles, silver escapes the center. It moves around the particle, and potentially gets out. Since the 1970s, scientists have been wondering exactly how this happens.
“I find it absolutely fascinating,” said Van Rooyen. She has been studying the TRISO-silver problem since 2006. “I have a natural tendency to know what is going on [inside the fuel].”

The Jan. 2, 2014 Idaho National Laboratory news release by Shannon Palus, which originated the news item, details how scientists saw the problem,

The silver seems to jump the silicon carbide layer as though by magic. There is no obvious point of exit, or forcible silver-shaped hole, to be found.  The transport mechanism that brings it from the inside out is a mystery that spans decades. It is a wrinkle in the plan to make TRISO the most efficient, and potentially the safest, fuel of the future.

In South Africa, Van Rooyen worked on a number of hypotheses for the TRISO problem. For example, did it piggyback out of the TRISO fuel particle attached to another element? Were there almost-too-tiny-to-see nanotubes forming in the silicon carbide layer?

One possibility seemed most probable to Van Rooyen. But to test it, to even begin to see if it was correct, she needed to be able to get a closer look. And she needed irradiated TRISO fuel.

Getting back to the notion of the irradiated tristructural-isotopic (TRISO) fuel particles being like a jawbreaker on the inside, i.e., made up of many layers, scientists have a term for the networks where each layer meets the next and where the grains that make up the layers align with each other, nanoroads. This concept inspired Van Rooyen’s approach (from the news release),

Could the nanoroads be the silver precipitate’s path out of the TRISO fuel particle? They do offer a path of lesser resistance, a point of potential weakness in the silicon carbide. The first step would be to see if silver could be found along these roads.

Van Rooyen’s method of investigation was a Scanning Transmission Electron Microscope operated by Yaqio Wu, a Boise State University research associate professor and instrument lead of the Materials and Characterization Suite at the Center for Advanced Energy Studies.  Somewhere along one of the nanoroad grain boundaries, Van Rooyen and Wu, along with materials engineer Tom Lillo, might be able to spot the silver precipitate.

“We were really like private investigators,” Van Rooyen said. The silver’s presence on the nanoroads — if that’s where it was — would be a lynchpin clue in the mystery.

After a year of patience and administrative work, she finally got her hands on actual, irradiated samples.

At a research briefing on the morning the team received the samples, they discussed the fact that they were looking for a needle in a haystack. For one, the bits of silver were so small. And not all TRISO particles emit silver. Would there even be silver in the specific sample they were looking at?

After years of exploring and discarding various hypotheses about the location of the silver, Van Rooyen and her team placed the irradiated TRISO particle under the electron microscope. This would be the closest, most careful look at the nanoroads in irradiated TRISO ever.

On that very afternoon, microscope operator Wu zoomed in and they found the silver precipitate. It was wedged at the intersection of two layers of TRISO coating, at the nanoroads between grains.

It was “an absolute wow moment,” said Van Rooyen. “We made such a commotion that people from other labs were coming to have a look.”

The journey is far from over. Next, Van Rooyen and her team will observe the silver to see how far it moves through the silicon carbide and try to determine exactly how it is able to get out. Time and hard work will tell if the nanoroads hypothesis is correct.

As is always the case, there’s the lead scientist and then there’s everyone else who helped make the discovery possible:

In addition to her colleagues Lillo and Wu, Van Rooyen would like to acknowledge Jim Madden for focused ion beam sample preparation; Jason Harp for isotope calculations; Joanne Taylor (Idaho State University); and Kristi Moser-McIntire (ISU) from CAES for their organization and support in the licensing of the CAES facility, which enabled the team to bring irradiated samples to the microscope.

Here’s an image of the TRISO particles,

INL leads research efforts to test advanced TRISO nuclear fuel, which has several layers of carbon and carbide that serve as the primary containment for radioactive material. Courtesy: Idaho National Laboratory

INL leads research efforts to test advanced TRISO nuclear fuel, which has several layers of carbon and carbide that serve as the primary containment for radioactive material. Courtesy: Idaho National Laboratory

Nanosilver—US Environmental Protection Agency (EPA) gets wrist slapped over nanosilver decision in textiles while Canadian Broadcasting Corporation (CBC) publishes article about nanosilver

I have two pieces about nanosilver today (Nov. 11 ,2013). The first concerns a Nov. 7, 2013 court ruling in favour of the Natural Resources Defense Council (NRDC) stating that the US Environmental Protection Agency (EPA) failed to follow its own rules when it accorded HeiQ Materials (a Swiss textile company) permission to market and sell its nanosilver-based antimicrobial fabric treatment in the US. From the NRDC’s Nov. 7, 2013 press release,

Court Ruling in NRDC’s Favor Should Limit Pesticide Nanosilver in Textiles

In a decision handed down today, the court said the EPA had improperly approved the use of nanosilver by one U.S. textile manufacturer [HeiQ Materials; headquarteed in Switzerland]. The court vacated the approval and sent it back to the agency for reevaluation. The lawsuit has been closely watched as a test case for the growing use of nanotechnology in consumer products.

“The court’s ruling puts us a step closer toward removing nanosilver from textiles,” said Mae Wu, an attorney in NRDC’s Health Program. “EPA shouldn’t have approved nanosilver in the first place. This is just one of a long line of decisions by the agency treating people and our environment as guinea pigs and laboratories for these untested pesticides.”

NRDC sued the U.S. Environmental Protection Agency in early 2012 to limit the use of nanosilver out of a concern for public health. Today the 9th U.S. Circuit Court of Appeals agreed with a key point NRDC raised: that the EPA didn’t follow its own rules for determining whether the pesticide’s use in products would be safe.

Beginning in December 2011, EPA approved the company HeiQ Materials to sell nanosilver used in fabrics for the next four years and required the company to provide data on toxicity for human health and aquatic organisms. In early 2012, NRDC filed a lawsuit against EPA seeking to block nanosilver’s use, contending, among several points, that the agency had ignored its own rules for determining the safety of nanosilver.

The key part of today’s Ninth Circuit ruling addressed EPA’s determination that there is no risk concern for toddlers exposed to nanosilver-treated textiles. The agency’s rules state that if there’s an aggregate exposure to the skin or through ingestion at or below a specific level, there is a risk of health concerns. But the Ninth Circuit found that the EPA had data showing that nanosilver was right at the level that should have triggered a finding of potential risk, but approved the pesticide anyway. That led to the Ninth Circuit vacating EPA’s approval and sending it back down to the agency for reevaluation.

Published in July 2013 (?), Nate Seltenrich’s article, Nanosilver: Weighing the Risks and BenefitsNanosilver: Weighing the Risks and Benefits, for the journal, Environmental Health Perspectives (EHP) [published with support from the National Institute of Environmental Health Sciences, National Institutes of Health, U.S. Department of Health and Human Services]) provides some insight into the court case and the issues,

It takes a special sort of case to spur attorneys into a debate over the drooling habits of toddlers. Yet that’s where lawyers from the Natural Resources Defense Council (NRDC), the U.S. Environmental Protection Agency (EPA), and Swiss chemicals company HeiQ found themselves in January 2013 as they debated in a federal appeals court the extent to which 1-year-olds and 3-year-olds chew, salivate, and swallow.1

At issue in the NRDC’s suit against the EPA, which is still awaiting ruling, was whether the agency was right in granting a conditional registration in December 2011 to a nanosilver-based antimicrobial fabric treatment manufactured by HeiQ.2 The EPA’s risk assessment was based in part on assumptions about exposure of 3-year-olds by sucking or chewing on nanosilver-laced textiles such as clothing, blankets, and pillowcases.

NRDC lawyer Catherine Rahm, however, begged to differ with the agency’s methods. In the January hearing, she argued that the agency record shows infants are more likely than any other subset of children to chew on fabrics that could contain the pesticide, and that if the agency were to recalculate its risk assessment based on the body weight of a 1-year-old, nanosilver concentrations in HeiQ’s product could result in potentially harmful exposures.

It’s an obscure but critical distinction as far as risk assessment goes. And given the implications for HeiQ and other companies looking to follow in its footsteps, the case has landed at the center of a prolonged conflict over the regulation of nanosilver and the growing deployment of this antimicrobial ingredient in a variety of commercial and consumer products.

Yet regardless of which side prevails in the case, the truth about nanosilver is not black and white. Even the loudest voices joining the NRDC’s call for strict regulation of nanosilver concede that context is key.

Seltenrich goes on to recount a little of the history of nanosilver and provide a brief a relatively balanced overview of the research. At the end of the article, he lists 37 reference documents and offers links, should you wish to research further. For anyone interested in HeiQ, here’s the company website.

The second nanosilver news item is from the CBC (Canadian Broadcasting Corporation( online. In an article by Evelyn Boychuk titled, Silver nanoparticle use spurs U.S. consumer database; Database tracks growing number of consumer goods containing nanomaterials, these nanoparticles are discussed within the context of a resuscitated Project on Emerging Nanotechnologies (PEN) Consumer Products Inventory (CPI), which was mentioned in my Oct. 28, 2013 posting titled: Rising from the dead: the inventory of nanotechnology-based consumer products. The articles offers an easy introduction to the topic and refers to a database of silver,nanotechnology in commercial products (complementary to the larger CPI).