Tag Archives: US

Discovering why nanoscale gold has catalytic properties

Gold’s glitter may have inspired poets and triggered wars, but its catalytic prowess has helped make chemical reactions greener and more efficient. (Image courtesy of iStock/sbayram) [downloaded from http://www1.lehigh.edu/news/scientists-uncover-secret-gold%E2%80%99s-catalytic-powers

Gold’s glitter may have inspired poets and triggered wars, but its catalytic prowess has helped make chemical reactions greener and more efficient. (Image courtesy of iStock/sbayram) [downloaded from http://www1.lehigh.edu/news/scientists-uncover-secret-gold%E2%80%99s-catalytic-powers

A Sept. 27, 2016 news item on phys.org describes a discovery made by scientists at Lehigh University (US),

Settling a decades-long debate, new research conclusively shows that a hierarchy of active species exists in gold on iron oxide catalysis designed for low temperature carbon monoxide oxidation; Nanoparticles, sub-nanometer clusters and dispersed atoms—as well as how the material is prepared—are all important for determining catalytic activity.

A Sept. 27, 2016 Lehigh University news release by Lori Friedman, which originated the news item, provides more information about the discovery that gold nanoparticles can be used in catalysis and about the discovery of why that’s possible,

Christopher J. Kiely calls the 1982 discovery by Masatake Haruta that gold (Au) possessed a high level of catalytic activity for carbon monoxide (CO) oxidation when deposited on a metal-oxide “a remarkable turn of events in nanotechnology”—remarkable because gold had long been assumed to be inert for catalysis.

Haruta showed that gold dispersed on iron oxide effectively catalyzed the conversion of harmful carbon monoxide into more benign carbon dioxide (CO2) at room temperatures—a reaction that is critical for the construction of fire fighters’ breathing masks and for removal of CO from hydrogen feeds for fuel cells. In fact, today gold catalysts are being exploited in a major way for the greening of many important reactions in the chemical industry, because they can lead to cleaner, more efficient reactions with fewer by-products.

Haruta and Graham J. Hutchings, who co-discovered the use of gold as a catalyst for different reactions, are noted as Thompson Reuters Citation Laureates and appear annually on the ScienceWatch Nobel Prize prediction list. Their pioneering work opened up a new area of scientific inquiry and kicked off a decades-long debate about which type of supported gold species are most effective for the CO oxidation reaction.

In 2008, using electron microscopy technology that was not yet available in the 1980s and ’90 s, Hutchings, the director of the Cardiff Catalysis Institute at Cardiff University worked with Kiely, the Harold B. Chambers Senior Professor Materials Science and Engineering at Lehigh, examined the structure of supported gold at the nanoscale. One nanometer (nm) is equal to one one-billionth of a meter or about the diameter of five atoms.

Using what was then a rare piece of equipment—Lehigh’s aberration-corrected JEOL 2200 FS scanning transmission electron microscope (STEM)—the team identified the co-existence of three distinct gold species: facetted nanoparticles larger than one nanometer in size, sub-clusters containing less than 20 atoms and individual gold atoms strewn over the support. Because only the larger gold nanoparticles had previously been detected, this created debate as to which of these species were responsible for the good catalytic behavior.

Haruta, professor of applied chemistry at Tokyo Metropolitan University, Hutchings and Kiely have been working collaboratively on this problem over recent years and are now the first to demonstrate conclusively that it is not the particles or the individual atoms or the clusters which are solely responsible for the catalysis—but that they all contribute to different degrees. Their results have been published in an article in Nature Communications titled: “Population and hierarchy of active species in gold iron oxide catalysts for carbon monoxide oxidation.”

“All of the species tend to co-exist in conventionally prepared catalysts and show some level of activity,” says Kiely. “They all do something—but some less efficiently than others.”

Their research revealed the sub-nanometer clusters and 1-3nm nanoparticles to be the most efficient for catalyzing this CO oxidation reaction, while larger particles were less so and the atoms even less.  Nevertheless, Kiely cautions, all the species present need to be considered to fully explain the overall measured activity of the catalyst.

Among the team’s other key findings: the measured activity of gold on iron oxide catalysts is exquisitely dependent on exactly how the material is prepared. Very small changes in synthesis parameters  influence the relative proportion and spatial distribution of these various Au species on the support material and thus have a big impact on its overall catalytic performance.

A golden opportunity

Building on their earlier work (published in a 2008 Science article), the team sought to find a robust way to quantitatively analyze the relative population distributions of nanoparticles of various sizes, sub-nm clusters and highly dispersed atoms in a given gold on iron oxide sample. By correlating this information with catalytic performance measurements, they then hoped to determine which species distribution would be optimal to produce the most efficient catalyst, in order to utilize the precious gold component in the most cost effective way.

Ultimately, it was a catalyst synthesis problem the team faced that offered them a golden opportunity to do just that.

During the collaboration, Haruta’s and Hutchings’ teams each prepared gold on iron oxide samples in their home labs in Tokyo and Cardiff. Even though both groups nominally utilized the same ‘co-precipitation’ synthesis method, it turned out that a final heat treatment step was beneficial to the catalytic performance for one set of materials but detrimental to the other. This observation provided a fascinating scientific conundrum that detailed electron microscopy studies performed by Qian He, one of Kiely’s PhD students at the time, was key to solving. Qian He is now a University Research Fellow at Cardiff University leading their electron microscopy effort.

“In the end, there were subtle differences in the order and speed in which each group added in their ingredients while preparing the material,” explains He. “When examined under the electron microscope, it was clear that the two slightly different methods produced quite different distributions of particles, clusters and dispersed atoms on the support.”

“Very small variations in the preparation route or thermal history of the sample can alter the relative balance of supported gold nanoparticles-to-clusters-to-atoms in the material and this manifests itself in the measured catalytic activity,” adds Kiely.

The group was able to compare this set of materials and correlate the Au species distributions with catalytic performance measurements, ultimately identifying the species distribution that was associated with greater catalytic efficiency.

Now that the team has identified the catalytic activity hierarchy associated with these supported gold species, the next step, says Kiely, will be to modify the synthesis method to positively influence that distribution to optimize the catalyst performance while making the most efficient use of the precious gold metal content.

“As a next stage to this study we would like to be able to observe gold on iron oxide materials in-situ within the electron microscope while the reaction is happening,” says Kiely.

Once again, it is next generation microscopy facilities that may hold the key to fulfilling gold’s promise as a pivotal player in green technology.

Despite the link to the paper already in the news release, here’s one that includes a citation,

Identification of Active Gold Nanoclusters on Iron Oxide Supports for CO Oxidation by Andrew A. Herzing, Christopher J. Kiely, Albert F. Carley, Philip Landon, Graham J. Hutchings. Science  05 Sep 2008: Vol. 321, Issue 5894, pp. 1331-1335 DOI: 10.1126/science.1159639

This paper is currently behind a paywall but, if you can wait one year, free access can be gained if you register (for free) with Science.

Powering up your graphene implants so you don’t get fried in the process

A Sept. 23, 2016 news item on phys.org describes a way of making graphene-based medical implants safer,

In the future, our health may be monitored and maintained by tiny sensors and drug dispensers, deployed within the body and made from graphene—one of the strongest, lightest materials in the world. Graphene is composed of a single sheet of carbon atoms, linked together like razor-thin chicken wire, and its properties may be tuned in countless ways, making it a versatile material for tiny, next-generation implants.

But graphene is incredibly stiff, whereas biological tissue is soft. Because of this, any power applied to operate a graphene implant could precipitously heat up and fry surrounding cells.

Now, engineers from MIT [Massachusetts Institute of Technology] and Tsinghua University in Beijing have precisely simulated how electrical power may generate heat between a single layer of graphene and a simple cell membrane. While direct contact between the two layers inevitably overheats and kills the cell, the researchers found they could prevent this effect with a very thin, in-between layer of water.

A Sept. 23, 2016 MIT news release by Emily Chu, which originated the news item, provides more technical details,

By tuning the thickness of this intermediate water layer, the researchers could carefully control the amount of heat transferred between graphene and biological tissue. They also identified the critical power to apply to the graphene layer, without frying the cell membrane. …

Co-author Zhao Qin, a research scientist in MIT’s Department of Civil and Environmental Engineering (CEE), says the team’s simulations may help guide the development of graphene implants and their optimal power requirements.

“We’ve provided a lot of insight, like what’s the critical power we can accept that will not fry the cell,” Qin says. “But sometimes we might want to intentionally increase the temperature, because for some biomedical applications, we want to kill cells like cancer cells. This work can also be used as guidance [for those efforts.]”

Sandwich model

Typically, heat travels between two materials via vibrations in each material’s atoms. These atoms are always vibrating, at frequencies that depend on the properties of their materials. As a surface heats up, its atoms vibrate even more, causing collisions with other atoms and transferring heat in the process.

The researchers sought to accurately characterize the way heat travels, at the level of individual atoms, between graphene and biological tissue. To do this, they considered the simplest interface, comprising a small, 500-nanometer-square sheet of graphene and a simple cell membrane, separated by a thin layer of water.

“In the body, water is everywhere, and the outer surface of membranes will always like to interact with water, so you cannot totally remove it,” Qin says. “So we came up with a sandwich model for graphene, water, and membrane, that is a crystal clear system for seeing the thermal conductance between these two materials.”

Qin’s colleagues at Tsinghua University had previously developed a model to precisely simulate the interactions between atoms in graphene and water, using density functional theory — a computational modeling technique that considers the structure of an atom’s electrons in determining how that atom will interact with other atoms.

However, to apply this modeling technique to the group’s sandwich model, which comprised about half a million atoms, would have required an incredible amount of computational power. Instead, Qin and his colleagues used classical molecular dynamics — a mathematical technique based on a “force field” potential function, or a simplified version of the interactions between atoms — that enabled them to efficiently calculate interactions within larger atomic systems.

The researchers then built an atom-level sandwich model of graphene, water, and a cell membrane, based on the group’s simplified force field. They carried out molecular dynamics simulations in which they changed the amount of power applied to the graphene, as well as the thickness of the intermediate water layer, and observed the amount of heat that carried over from the graphene to the cell membrane.

Watery crystals

Because the stiffness of graphene and biological tissue is so different, Qin and his colleagues expected that heat would conduct rather poorly between the two materials, building up steeply in the graphene before flooding and overheating the cell membrane. However, the intermediate water layer helped dissipate this heat, easing its conduction and preventing a temperature spike in the cell membrane.

Looking more closely at the interactions within this interface, the researchers made a surprising discovery: Within the sandwich model, the water, pressed against graphene’s chicken-wire pattern, morphed into a similar crystal-like structure.

“Graphene’s lattice acts like a template to guide the water to form network structures,” Qin explains. “The water acts more like a solid material and makes the stiffness transition from graphene and membrane less abrupt. We think this helps heat to conduct from graphene to the membrane side.”

The group varied the thickness of the intermediate water layer in simulations, and found that a 1-nanometer-wide layer of water helped to dissipate heat very effectively. In terms of the power applied to the system, they calculated that about a megawatt of power per meter squared, applied in tiny, microsecond bursts, was the most power that could be applied to the interface without overheating the cell membrane.

Qin says going forward, implant designers can use the group’s model and simulations to determine the critical power requirements for graphene devices of different dimensions. As for how they might practically control the thickness of the intermediate water layer, he says graphene’s surface may be modified to attract a particular number of water molecules.

“I think graphene provides a very promising candidate for implantable devices,” Qin says. “Our calculations can provide knowledge for designing these devices in the future, for specific applications, like sensors, monitors, and other biomedical applications.”

This research was supported in part by the MIT International Science and Technology Initiative (MISTI): MIT-China Seed Fund, the National Natural Science Foundation of China, DARPA [US Defense Advanced Research Projects Agency], the Department of Defense (DoD) Office of Naval Research, the DoD Multidisciplinary Research Initiatives program, the MIT Energy Initiative, and the National Science Foundation.

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

Intercalated water layers promote thermal dissipation at bio–nano interfaces by Yanlei Wang, Zhao Qin, Markus J. Buehler, & Zhiping Xu. Nature Communications 7, Article number: 12854 doi:10.1038/ncomms12854 Published 23 September 2016

This paper is open access.

Graphene Malaysia 2016 gathering and Malaysia’s National Graphene Action Plan 2020

Malaysia is getting ready to host a graphene conference according to an Oct. 10, 2016 news item on Nanotechnology Now,

The Graphene Malaysia 2016 [Nov. 8 – 9, 2016] (www.graphenemalaysiaconf.com) is jointly organized by NanoMalaysia Berhad and Phantoms Foundation. The conference will be centered on graphene industry interaction and collaborative innovation. The event will be launched under the National Graphene Action Plan 2020 (NGAP 2020), which will generate about 9,000 jobs and RM20 (US$4.86) billion GNI impact by the year 2020.

First speakers announced:
Murni Ali (Nanomalaysia, Malaysia) | Francesco Bonaccorso (Istituto Italiano di Tecnologia, Italy) | Antonio Castro Neto (NUS, Singapore) | Antonio Correia (Phantoms Foundation, Spain)| Pedro Gomez-Romero (ICN2 (CSIC-BIST), Spain) | Shu-Jen Han (Nanoscale Science & Technology IBM T.J. Watson Research Center, USA) | Kuan-Tsae Huang (AzTrong, USA/Taiwan) | Krzysztof Koziol (FGV Cambridge Nanosystems, UK) | Taavi Madiberk (Skeleton Technologies, Estonia) | Richard Mckie (BAE Systems, UK) | Pontus Nordin (Saab AB, Saab Aeronautics, Sweden) | Elena Polyakova (Graphene Laboratories Inc., USA) | Ahmad Khairuddin Abdul Rahim (Malaysian Investment Development Authority (MIDA), Malaysia) | Adisorn Tuantranont (Thailand Organic and Printed Electronics Innovation Center, Thailand) |Archana Venugopal (Texas Instruments, USA) | Won Jong Yoo (Samsung-SKKU Graphene-2D Center (SSGC), South Korea) | Hongwei Zhu (Tsinghua University, China)

You can check for more information and deadlines in the Nanotechnology Now Oct. 10, 2016 news item.

The Graphene Malalysia 2016 conference website can be found here and Malaysia’s National Graphene Action Plan 2020, which is well written, can be found here (PDF).  This portion from the executive summary offers some insight into Malyasia’s plans to launch itself into the world of high income nations,

Malaysia’s aspiration to become a high-income nation by 2020 with improved jobs and better outputs is driving the country’s shift away from “business as usual,” and towards more innovative and high value add products. Within this context, and in accordance with National policies and guidelines, Graphene, an emerging, highly versatile carbon-based nanomaterial, presents a unique opportunity for Malaysia to develop a high value economic ecosystem within its industries.  Isolated only in 2004, Graphene’s superior physical properties such as electrical/ thermal conductivity, high strength and high optical transparency, combined with its manufacturability have raised tremendous possibilities for its application across several functions and make it highly interesting for several applications and industries.  Currently, Graphene is still early in its development cycle, affording Malaysian companies time to develop their own applications instead of relying on international intellectual property and licenses.

Considering the potential, several leading countries are investing heavily in associated R&D. Approaches to Graphene research range from an expansive R&D focus (e.g., U.S. and the EU) to more focused approaches aimed at enhancing specific downstream applications with Graphene (e.g., South Korea). Faced with the need to push forward a multitude of development priorities, Malaysia must be targeted in its efforts to capture Graphene’s potential, both in terms of “how to compete” and “where to compete”. This National Graphene Action Plan 2020 lays out a set of priority applications that will be beneficial to the country as a whole and what the government will do to support these efforts.

Globally, much of the Graphene-related commercial innovation to date has been upstream, with producers developing techniques to manufacture Graphene at scale. There has also been some development in downstream sectors, as companies like Samsung, Bayer MaterialScience, BASF and Siemens explore product enhancement with Graphene in lithium-ion battery anodes and flexible displays, and specialty plastic and rubber composites. However the speed of development has been uneven, offering Malaysian industries willing to invest in innovation an opportunity to capture the value at stake. Since any innovation action plan has to be tailored to the needs and ambitions of local industry, Malaysia will focus its Graphene action plan initially on larger domestic industries (e.g., rubber) and areas already being targeted by the government for innovation such as energy storage for electric vehicles and conductive inks.

In addition to benefiting from the physical properties of Graphene, Malaysian downstream application providers may also capture the benefits of a modest input cost advantage for the domestic production of Graphene.  One commonly used Graphene manufacturing technique, the chemical vapour deposition (CVD) production method, requires methane as an input, which can be sourced economically from local biomass. While Graphene is available commercially from various producers around the world, downstream players may be able to enjoy some cost advantage from local Graphene supply. In addition, co-locating with a local producer for joint product development has the added benefit of speeding up the R&D lifecycle.

That business about finding downstream applications could also to the Canadian situation where we typically offer our resources (upstream) but don’t have an active downstream business focus. For example, we have graphite mines in Ontario and Québec which supply graphite flakes for graphene production which is all upstream. Less well developed are any plans for Canadian downstream applications.

Finally, it was interesting to note that the Phantoms Foundation is organizing this Malaysian conference since the same organization is organizing the ‘2nd edition of Graphene & 2D Materials Canada 2016 International Conference & Exhibition’ (you can find out more about the Oct. 18 – 20, 2016 event in my Sept. 23, 2016 posting). I think the Malaysians have a better title for their conference, far less unwieldy.

Tattoo therapy for chronic disease?

It’s good to wake up to something truly new. In this case, it’s using tattoos and nanoparticles for medical applications. From a Sept. 22, 2016 news item on ScienceDaily,

A temporary tattoo to help control a chronic disease might someday be possible, according to scientists at Baylor College of Medicine [Texas, US] who tested antioxidant nanoparticles created at Rice University [Texas, US].

A Sept. 22, 2016 Rice University news release, which originated the news item, provides more information and some good explanations of the terms used (Note: Links have been removed),

A proof-of-principle study led by Baylor scientist Christine Beeton published today by Nature’s online, open-access journal Scientific Reports shows that nanoparticles modified with polyethylene glycol are conveniently choosy as they are taken up by cells in the immune system.

That could be a plus for patients with autoimmune diseases like multiple sclerosis, one focus of study at the Beeton lab. “Placed just under the skin, the carbon-based particles form a dark spot that fades over about one week as they are slowly released into the circulation,” Beeton said.

T and B lymphocyte cells and macrophages are key components of the immune system. However, in many autoimmune diseases such as multiple sclerosis, T cells are the key players. One suspected cause is that T cells lose their ability to distinguish between invaders and healthy tissue and attack both.

In tests at Baylor, nanoparticles were internalized by T cells, which inhibited their function, but ignored by macrophages. “The ability to selectively inhibit one type of cell over others in the same environment may help doctors gain more control over autoimmune diseases,” Beeton said.

“The majority of current treatments are general, broad-spectrum immunosuppressants,” said Redwan Huq, lead author of the study and a graduate student in the Beeton lab. “They’re going to affect all of these cells, but patients are exposed to side effects (ranging) from infections to increased chances of developing cancer. So we get excited when we see something new that could potentially enable selectivity.” Since the macrophages and other splenic immune cells are unaffected, most of a patient’s existing immune system remains intact, he said.

The soluble nanoparticles synthesized by the Rice lab of chemist James Tour have shown no signs of acute toxicity in prior rodent studies, Huq said. They combine polyethylene glycol with hydrophilic carbon clusters, hence their name, PEG-HCCs. The carbon clusters are 35 nanometers long, 3 nanometers wide and an atom thick, and bulk up to about 100 nanometers in globular form with the addition of PEG. They have proven to be efficient scavengers of reactive oxygen species called superoxide molecules, which are expressed by cells the immune system uses to kill invading microorganisms.

T cells use superoxide in a signaling step to become activated. PEG-HCCs remove this superoxide from the T cells, preventing their activation without killing the cells.

Beeton became aware of PEG-HCCs during a presentation by former Baylor graduate student Taeko Inoue, a co-author of the new study. “As she talked, I was thinking, ‘That has to work in models of multiple sclerosis,’” Beeton said. “I didn’t have a good scientific rationale, but I asked for a small sample of PEG-HCCs to see if they affected immune cells.

“We found they affected the T lymphocytes and not the other splenic immune cells, like the macrophages. It was completely unexpected,” she said.

The Baylor lab’s tests on animal models showed that small amounts of PEG-HCCs injected under the skin are slowly taken up by T lymphocytes, where they collect and inhibit the cell’s function. They also found the nanoparticles did not remain in T cells and dispersed within days after uptake by the cells.

“That’s an issue because you want a drug that’s in the system long enough to be effective, but not so long that, if you have a problem, you can’t remove it,” Beeton said. “PEG-HCCs can be administered for slow release and don’t stay in the system for long. This gives us much better control over the circulating half-life.”

“The more we study the abilities of these nanoparticles, the more surprised we are at how useful they could be for medical applications,” Tour said. The Rice lab has published papers with collaborators at Baylor and elsewhere on using functionalized nanoparticles to deliver cancer drugs to tumors and to quench the overproduction of superoxides after traumatic brain injuries.

Beeton suggested delivering carbon nanoparticles just under the skin rather than into the bloodstream would keep them in the system longer, making them more available for uptake by T cells. And the one drawback – a temporary but visible spot on the skin that looks like a tattoo – could actually be a perk to some.

“We saw it made a black mark when we injected it, and at first we thought that’s going to be a real problem if we ever take it into the clinic,” Beeton said. “But we can work around that. We can inject into an area that’s hidden, or use micropattern needles and shape it.

“I can see doing this for a child who wants a tattoo and could never get her parents to go along,” she said. “This will be a good way to convince them.”

The research was supported by Baylor College of Medicine, the National Multiple Sclerosis Society, National Institutes of Health, the Dan L. Duncan Cancer Center, John S. Dunn Gulf Coast Consortium for Chemical Genomics and the U.S. Army-funded Traumatic Brain Injury Consortium.

That’s an interesting list of funders at the end of the news release.

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

Preferential uptake of antioxidant carbon nanoparticles by T lymphocytes for immunomodulation by Redwan Huq, Errol L. G. Samuel, William K. A. Sikkema, Lizanne G. Nilewski, Thomas Lee, Mark R. Tanner, Fatima S. Khan, Paul C. Porter, Rajeev B. Tajhya, Rutvik S. Patel, Taeko Inoue, Robia G. Pautler, David B. Corry, James M. Tour, & Christine Beeton. Scientific Reports 6, Article number: 33808 (2016) doi:10.1038/srep33808 Published online: 22 September 2016

This paper is open access.

Here’s an image provided by the researchers,

Polyethylene glycol-hydrophilic carbon clusters developed at Rice University were shown to be selectively taken up by T cells, which inhibits their function, in tests at Baylor College of Medicine. The researchers said the nanoparticles could lead to new strategies for controlling autoimmune diseases like multiple sclerosis. (Credit: Errol Samuel/Rice University) - See more at: http://news.rice.edu/2016/09/22/tattoo-therapy-could-ease-chronic-disease/#sthash.sIfs3b0S.dpuf

Polyethylene glycol-hydrophilic carbon clusters developed at Rice University were shown to be selectively taken up by T cells, which inhibits their function, in tests at Baylor College of Medicine. The researchers said the nanoparticles could lead to new strategies for controlling autoimmune diseases like multiple sclerosis. (Credit: Errol Samuel/Rice University)

2016 Nobel Chemistry Prize for molecular machines

Wednesday, Oct. 5, 2016 was the day three scientists received the Nobel Prize in Chemistry for their work on molecular machines, according to an Oct. 5, 2016 news item on phys.org,

Three scientists won the Nobel Prize in chemistry on Wednesday [Oct. 5, 2016] for developing the world’s smallest machines, 1,000 times thinner than a human hair but with the potential to revolutionize computer and energy systems.

Frenchman Jean-Pierre Sauvage, Scottish-born Fraser Stoddart and Dutch scientist Bernard “Ben” Feringa share the 8 million kronor ($930,000) prize for the “design and synthesis of molecular machines,” the Royal Swedish Academy of Sciences said.

Machines at the molecular level have taken chemistry to a new dimension and “will most likely be used in the development of things such as new materials, sensors and energy storage systems,” the academy said.

Practical applications are still far away—the academy said molecular motors are at the same stage that electrical motors were in the first half of the 19th century—but the potential is huge.

Dexter Johnson in an Oct. 5, 2016 posting on his Nanoclast blog (on the IEEE [Institute of Electrical and Electronics Engineers] website) provides some insight into the matter (Note: A link has been removed),

In what seems to have come both as a shock to some of the recipients and a confirmation to all those who envision molecular nanotechnology as the true future of nanotechnology, Bernard Feringa, Jean-Pierre Sauvage, and Sir J. Fraser Stoddart have been awarded the 2016 Nobel Prize in Chemistry for their development of molecular machines.

The Nobel Prize was awarded to all three of the scientists based on their complementary work over nearly three decades. First, in 1983, Sauvage (currently at Strasbourg University in France) was able to link two ring-shaped molecules to form a chain. Then, eight years later, Stoddart, a professor at Northwestern University in Evanston, Ill., demonstrated that a molecular ring could turn on a thin molecular axle. Then, eight years after that, Feringa, a professor at the University of Groningen, in the Netherlands, built on Stoddardt’s work and fabricated a molecular rotor blade that could spin continually in the same direction.

Speaking of the Nobel committee’s selection, Donna Nelson, a chemist and president of the American Chemical Society told Scientific American: “I think this topic is going to be fabulous for science. When the Nobel Prize is given, it inspires a lot of interest in the topic by other researchers. It will also increase funding.” Nelson added that this line of research will be fascinating for kids. “They can visualize it, and imagine a nanocar. This comes at a great time, when we need to inspire the next generation of scientists.”

The Economist, which appears to be previewing an article about the 2016 Nobel prizes ahead of the print version, has this to say in its Oct. 8, 2016 article,

BIGGER is not always better. Anyone who doubts that has only to look at the explosion of computing power which has marked the past half-century. This was made possible by continual shrinkage of the components computers are made from. That success has, in turn, inspired a search for other areas where shrinkage might also yield dividends.

One such, which has been poised delicately between hype and hope since the 1990s, is nanotechnology. What people mean by this term has varied over the years—to the extent that cynics might be forgiven for wondering if it is more than just a fancy rebranding of the word “chemistry”—but nanotechnology did originally have a fairly clear definition. It was the idea that machines with moving parts could be made on a molecular scale. And in recognition of this goal Sweden’s Royal Academy of Science this week decided to award this year’s Nobel prize for chemistry to three researchers, Jean-Pierre Sauvage, Sir Fraser Stoddart and Bernard Feringa, who have never lost sight of nanotechnology’s original objective.

Optimists talk of manufacturing molecule-sized machines ranging from drug-delivery devices to miniature computers. Pessimists recall that nanotechnology is a field that has been puffed up repeatedly by both researchers and investors, only to deflate in the face of practical difficulties.

There is, though, reason to hope it will work in the end. This is because, as is often the case with human inventions, Mother Nature has got there first. One way to think of living cells is as assemblies of nanotechnological machines. For example, the enzyme that produces adenosine triphosphate (ATP)—a molecule used in almost all living cells to fuel biochemical reactions—includes a spinning molecular machine rather like Dr Feringa’s invention. This works well. The ATP generators in a human body turn out so much of the stuff that over the course of a day they create almost a body-weight’s-worth of it. Do something equivalent commercially, and the hype around nanotechnology might prove itself justified.

Congratulations to the three winners!

Breathing nanoparticles into your brain

Thanks to Dexter Johnson and his Sept. 8, 2016 posting (on the Nanoclast blog on the IEEE [Institute for Electrical and Electronics Engineers]) for bringing this news about nanoparticles in the brain to my attention (Note: Links have been removed),

An international team of researchers, led by Barbara Maher, a professor at Lancaster University, in England, has found evidence that suggests that the nanoparticles that were first detected in the human brain over 20 years ago may have an external rather an internal source.

These magnetite nanoparticles are an airborne particulate that are abundant in urban environments and formed by combustion or friction-derived heating. In other words, they have been part of the pollution in the air of our cities since the dawn of the Industrial Revolution.

However, according to Andrew Maynard, a professor at Arizona State University, and a noted expert on the risks associated with nanomaterials,  the research indicates that this finding extends beyond magnetite to any airborne nanoscale particles—including those deliberately manufactured.

“The findings further support the possibility of these particles entering the brain via the olfactory nerve if inhaled.  In this respect, they are certainly relevant to our understanding of the possible risks presented by engineered nanomaterials—especially those that are iron-based and have magnetic properties,” said Maynard in an e-mail interview with IEEE Spectrum. “However, ambient exposures to airborne nanoparticles will typically be much higher than those associated with engineered nanoparticles, simply because engineered nanoparticles will usually be manufactured and handled under conditions designed to avoid release and exposure.”

A Sept. 5, 2016 University of Lancaster press release made the research announcement,

Researchers at Lancaster University found abundant magnetite nanoparticles in the brain tissue from 37 individuals aged three to 92-years-old who lived in Mexico City and Manchester. This strongly magnetic mineral is toxic and has been implicated in the production of reactive oxygen species (free radicals) in the human brain, which are associated with neurodegenerative diseases including Alzheimer’s disease.

Professor Barbara Maher, from Lancaster Environment Centre, and colleagues (from Oxford, Glasgow, Manchester and Mexico City) used spectroscopic analysis to identify the particles as magnetite. Unlike angular magnetite particles that are believed to form naturally within the brain, most of the observed particles were spherical, with diameters up to 150 nm, some with fused surfaces, all characteristic of high-temperature formation – such as from vehicle (particularly diesel) engines or open fires.

The spherical particles are often accompanied by nanoparticles containing other metals, such as platinum, nickel, and cobalt.

Professor Maher said: “The particles we found are strikingly similar to the magnetite nanospheres that are abundant in the airborne pollution found in urban settings, especially next to busy roads, and which are formed by combustion or frictional heating from vehicle engines or brakes.”

Other sources of magnetite nanoparticles include open fires and poorly sealed stoves within homes. Particles smaller than 200 nm are small enough to enter the brain directly through the olfactory nerve after breathing air pollution through the nose.

“Our results indicate that magnetite nanoparticles in the atmosphere can enter the human brain, where they might pose a risk to human health, including conditions such as Alzheimer’s disease,” added Professor Maher.

Leading Alzheimer’s researcher Professor David Allsop, of Lancaster University’s Faculty of Health and Medicine, said: “This finding opens up a whole new avenue for research into a possible environmental risk factor for a range of different brain diseases.”

Damian Carrington’s Sept. 5, 2016 article for the Guardian provides a few more details,

“They [the troubling magnetite particles] are abundant,” she [Maher] said. “For every one of [the crystal shaped particles] we saw about 100 of the pollution particles. The thing about magnetite is it is everywhere.” An analysis of roadside air in Lancaster found 200m magnetite particles per cubic metre.

Other scientists told the Guardian the new work provided strong evidence that most of the magnetite in the brain samples come from air pollution but that the link to Alzheimer’s disease remained speculative.

For anyone who might be concerned about health risks, there’s this from Andrew Maynard’s comments in Dexter Johnson’s Sept. 8, 2016 posting,

“In most workplaces, exposure to intentionally made nanoparticles is likely be small compared to ambient nanoparticles, and so it’s reasonable to assume—at least without further data—that this isn’t a priority concern for engineered nanomaterial production,” said Maynard.

While deliberate nanoscale manufacturing may not carry much risk, Maynard does believe that the research raises serious questions about other manufacturing processes where exposure to high concentrations of airborne nanoscale iron particles is common—such as welding, gouging, or working with molten ore and steel.

It seems everyone is agreed that the findings are concerning but I think it might be good to remember that the percentage of people who develop Alzheimer’s Disease is much smaller than the population of people who have crystals in their brains. In other words, these crystals might (they don’t know) be a factor and likely there would have to be one or more factors to create the condition for developing Alzheimer’s.

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

Magnetite pollution nanoparticles in the human brain by Barbara A. Maher, Imad A. M. Ahmed, Vassil Karloukovski, Donald A. MacLaren, Penelope G. Fouldsd, David Allsop, David M. A. Mann, Ricardo Torres-Jardón, and Lilian Calderon-Garciduenas. PNAS [Proceedings of the National Academy of Sciences] doi: 10.1073/pnas.1605941113

This paper is behind a paywall but Dexter’s posting offers more detail for those who are still curious.

Ginger-derived nano-lipids for colorectal cancer

Didier Merlin’s team at the US Dept. of Veteran’s Affairs along with researchers from Georgia State University and from two Chinese universities have published more research on what they are calling, GDNPs, or ginger-derived nanoparticles. (See my Sept. 8, 2016 posting for my first post about ginger nanoparticles and the US Dept. of Veterans Affairs.)

Ginger, well known for relieving nausea, may soon be able to claim another health benefit according to a Sept. 6, 2016 news item on ScienceDaily,

Edible ginger-derived nano-lipids created from a specific population of ginger nanoparticles show promise for effectively targeting and delivering chemotherapeutic drugs used to treat colon cancer, according to a study by researchers at the Institute for Biomedical Sciences at Georgia State University, the Atlanta Veterans Affairs Medical Center and Wenzhou Medical University and Southwest University in China.

A Sept. 6, 2016 Georgia State University news release (also on EurekAlert), which originated the news item, describes both the situation with colorectal cancer in the US and the research,

Colorectal cancer is the third most common cancer among men and women in the United States, and the second-leading cause of cancer-related deaths among men and women worldwide. The incidence of colorectal cancer has increased over the last few years, with about one million new cases diagnosed annually. Non-targeted chemotherapy is the most common therapeutic strategy available for colon cancer patients, but this treatment method is unable to distinguish between cancerous and healthy cells, leading to poor therapeutic effects on tumor cells and severe toxic side effects on healthy cells. Enabling chemotherapeutic drugs to target cancer cells would be a major development in the treatment of colon cancer.

In this study, the researchers isolated a specific nanoparticle population from edible ginger (GDNP 2) and reassembled their lipids, naturally occurring molecules that include fats, to form ginger-derived nano-lipids, also known as nanovectors. To achieve accurate targeting of tumor tissues, the researchers modified the nanovectors with folic acid to create FA-modified nanovectors (FA nanovectors). Folic acid shows high-affinity binding to the folate receptors that are highly expressed on many tumors and almost undetectable on non-tumor cells.

The FA nanovectors were tested as a delivery platform for doxorubicin, a chemotherapeutic drug used to treat colon cancer. The researchers found that doxorubicin was efficiently loaded into the FA nanovectors, and the FA nanovectors were efficiently taken up by colon cancer cells, exhibited excellent biocompatibility and successfully inhibited tumor growth. Compared to a commercially available option for delivering doxorubicin, the FA nanovectors released the drug more rapidly in an acidic pH that resembled the tumor environment, suggesting this delivery strategy could decrease the severe side effects of doxorubicin. These findings were published in the journal Molecular Therapy.

“Our results show that FA nanovectors made of edible ginger-derived lipids could shift the current paradigm of drug delivery away from artificially synthesized nanoparticles toward the use of nature-derived nanovectors from edible plants,” said Dr. Didier Merlin, a professor in the Institute for Biomedical Sciences at Georgia State and a Research Career Scientist at the VA Medical Center. “Because they are nontoxic and can be produced on a large scale, FA nanovectors derived from edible plants could represent one of the safest targeted therapeutic delivery platforms.”

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

Edible Ginger-derived Nano-lipids Loaded with Doxorubicin as a Novel Drug-delivery Approach for Colon Cancer Therapy by Mingzhen Zhang, Bo Xiao, Huan Wang, Moon Kwon Han, Zhan Zhang, Emilie Viennois, Changlong Xu, and Didier Merlin. Molecular Therapy (2016); doi:10.1038/mt.2016.159 Advance online publication 13 September 2016

This paper is behind a paywall.

Sniffing for art conservation

The American Chemical Society (ACS) has produced a video titled, “How that ‘old book smell’ could save priceless artifacts” according to their Sept. 6, 2016 news release on EurekAlert,

Odor-detecting devices like Breathalyzers have been used for years to determine blood-alcohol levels in drunk drivers. Now, researchers are using a similar method to sniff out the rate of decay in historic art and artifacts. By tracking the chemicals in “old book smell” and similar odors, conservators can react quickly to preserve priceless art and artifacts at the first signs of decay. In this Speaking of Chemistry, Sarah Everts explains how cultural-heritage science uses the chemistry of odors to save books, vintage jewelry and even early Legos. …

Here’s the video,

Heritage Smells, the UK project mentioned in the video, is now completed but it was hosted by the University of Strathclyde and more project information can be found here.

Ministry’s new women’s shirt: a technical marvel

It seems there’s another entry into the textile business, a women’s dress shirt made of a technical textile. A Sept. 13, 2016 article by Elizabeth Segran for Fast Company describes this ‘miracle’ piece of apparel,

There are few items of clothing professional women love more than a well-draped silk shirt. They’re the equivalent of men’s well-tailored Oxford shirts: classic, elegant, and versatile enough to look appropriate in almost any business context. But they’re also difficult to maintain: Silk wrinkles easily, doesn’t absorb perspiration, and needs to be dry cleaned.

Boston-based fashion brand Ministry (formerly Ministry of Supply) has heard our lament. …

Ministry gathered …  feedback and spent two years creating a high-performance women’s work shirt as part of its debut womenswear collection, launching today [Sept. 13, 2016]. Until now, the five-year-old company has been focused on creating menswear made with cutting-edge new textiles, but cofounder Gihan Amarasiriwardena explains that when they were developing the womenswear collection, they didn’t just remake their men’s garments in women’s sizes.

Here’s an image of the shirt in black,

[downloaded from http://ministry.co/collections/womens]

[downloaded from http://ministry.co/collections/womens]

Segran’s article mostly extolls its benefits but there is a little technical information,

Their brand-new, aptly named Easier Than Silk Shirt looks and feels like silk, but is actually made from a Japanese technical fabric (i.e., a textile engineered to perform functions, like protecting the wearer from extremely high temperatures). It drapes nicely, wicks moisture, is wrinkle-resistant, and can be thrown in a regular washer and dryer. I tested the shirt on a typical Monday. This meant getting dressed at 7 a.m., taking my baby to a health checkup—where she proceeded to drool on me—wiping myself off for a lunch interview, then heading to a coffee shop to write for several hours before going to a book launch party. By the time I got home that evening and looked in the mirror, the shirt was somehow crease-free and there were no moisture blotches in sight.

When Ministry claims to “engineer a shirt,” it does not mean this in a metaphorical sense. The by [sic] three MIT students, Amarasiriwardena, Aman Advani, and Kit Hickey; the former two were trained as engineers. Every aspect of Ministry’s design process incorporates scientific thinking, from introducing NASA temperature-regulating textile technology into dress shirts to using equipment to test each garment before it hits the market. The Ministry headquarters in Boston is full of machines, including one that pulls at fabric to see how well it is able to recover from being stretched, and computer systems that offer 3D modeling of the human form.

I wonder if Teijin (first mentioned here in a July 19, 2010 posting about their now defunct ‘morphotex’ [based on the nanostructures on a Morpho butterfly’s wing] fabric) is the Japanese company producing Ministry’s technical textile. Ministry’s company website is less focused on the technology than on the retail aspect of their business so if the technical information is there, it’s not immediately obvious.

Graphene in the bone

An international team of US, Brazilian, and Indian scientists has developed a graphene-based material they believe could be used in bone implants. From a Sept. 2, 2016 news item on ScienceDaily,

Flakes of graphene welded together into solid materials may be suitable for bone implants, according to a study led by Rice University scientists.

The Rice lab of materials scientist Pulickel Ajayan and colleagues in Texas, Brazil and India used spark plasma sintering to weld flakes of graphene oxide into porous solids that compare favorably with the mechanical properties and biocompatibility of titanium, a standard bone-replacement material.

A Sept. 2, 2016 Rice University news release (also on EurekAlert), which originated the news item, explains the work in more detail,

The researchers believe their technique will give them the ability to create highly complex shapes out of graphene in minutes using graphite molds, which they believe would be easier to process than specialty metals.

“We started thinking about this for bone implants because graphene is one of the most intriguing materials with many possibilities and it’s generally biocompatible,” said Rice postdoctoral research associate Chandra Sekhar Tiwary, co-lead author of the paper with Dibyendu Chakravarty of the International Advanced Research Center for Powder Metallurgy and New Materials in Hyderabad, India. “Four things are important: its mechanical properties, density, porosity and biocompatibility.”

Tiwary said spark plasma sintering is being used in industry to make complex parts, generally with ceramics. “The technique uses a high pulse current that welds the flakes together instantly. You only need high voltage, not high pressure or temperatures,” he said. The material they made is nearly 50 percent porous, with a density half that of graphite and a quarter of titanium metal. But it has enough compressive strength — 40 megapascals — to qualify it for bone implants, he said. The strength of the bonds between sheets keeps it from disintegrating in water.

The researchers controlled the density of the material by altering the voltage that delivers the highly localized blast of heat that makes the nanoscale welds. Though the experiments were carried out at room temperature, the researchers made graphene solids of various density by raising these sintering temperatures from 200 to 400 degrees Celsius. Samples made at local temperatures of 300 C proved best, Tiwary said. “The nice thing about two-dimensional materials is that they give you a lot of surface area to connect. With graphene, you just need to overcome a small activation barrier to make very strong welds,” he said.

With the help of colleagues at Hysitron in Minnesota, the researchers measured the load-bearing capacity of thin sheets of two- to five-layer bonded graphene by repeatedly stressing them with a picoindenter attached to a scanning electron microscope and found they were stable up to 70 micronewtons. Colleagues at the University of Texas MD Anderson Cancer Center successfully cultured cells on the material to show its biocompatibility. As a bonus, the researchers also discovered the sintering process has the ability to reduce graphene oxide flakes to pure bilayer graphene, which makes them stronger and more stable than graphene monolayers or graphene oxide.

“This example demonstrates the possible use of unconventional materials in conventional technologies,” Ajayan said. “But these transitions can only be made if materials such as 2-D graphene layers can be scalably made into 3-D solids with appropriate density and strength.

“Engineering junctions and strong interfaces between nanoscale building blocks is the biggest challenge in achieving such goals, but in this case, spark plasma sintering seems to be effective in joining graphene sheets to produce strong 3-D solids,” he said.

The researchers have produced an animation depicting of graphene oxide layers being stacked,

A molecular dynamics simulation shows how graphene oxide layers stack when welded by spark plasma sintering. The presence of oxygen molecules at left prevents the graphene layers from bonding, as they do without oxygen at right. Courtesy of the Ajayan and Galvão groups

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

3D Porous Graphene by Low-Temperature Plasma Welding for Bone Implants by Dibyendu Chakravarty, Chandra Sekhar Tiwary, Cristano F. Woellner, Sruthi Radhakrishnan4, Soumya Vinod, Sehmus Ozden, Pedro Alves da Silva Autreto, Sanjit Bhowmick, Syed Asif, Sendurai A Mani, Douglas S. Galvao, and Pulickel M. Ajayan. Advanced Materials DOI: 10.1002/adma.201603146 Version of Record online: 26 AUG 2016

© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

This paper is behind a paywall.