Tag Archives: Northwestern University

Measurably fewer nanoparticles in São Paulo’s (Brazil) air after ethanol use

An Aug. 28, 2017 news item on Nanotechnology Now features news about nanoparticles and the environment in São Paulo, Brazil,

When ethanol prices at the pump rise for whatever reason, it becomes economically advantageous for drivers of dual-fuel vehicles to fill up with gasoline. However, the health of the entire population pays a high price: substitution of gasoline for ethanol leads to a 30% increase in the atmospheric concentration of ultrafine particulate matter, which consists of particles with a diameter of less than 50 nanometers (nm).

An Aug. 23, 2017 Fundação de Amparo à Pesquisa do Estado de São Paulo (The São Paulo Research Foundation [FAPESP]) press release, which originated the news item, explains further,

The phenomenon was detected in São Paulo City, Brazil, in a study supported by FAPESP and published in July 2017 in Nature Communications.

“These polluting nanoparticles are so tiny that they behave like gas molecules. When inhaled, they can penetrate the respiratory system’s defensive barriers and reach the pulmonary alveoli, so that potentially toxic substances enter the bloodstream and may increase the incidence of respiratory and cardiovascular problems,” said Paulo Artaxo, Full Professor at the University of São Paulo’s Physics Institute (IF-USP) and a co-author of the study.

Levels of ultrafine particulate matter in the atmosphere are neither monitored nor regulated by environmental agencies not only in Brazil but practically anywhere in the world, according to Artaxo. The São Paulo State Environmental Corporation (CETESB), for example, routinely monitors only solid particles with diameters of 10,000 nm (PM10) and 2,500 nm (PM2.5) – as well as other gaseous pollutants such as ozone (O3), carbon monoxide (CO) and nitrogen dioxide (NO2).

“Between 75% and 80% of the mass of the nanoparticles we measured in this study corresponds to organic compounds emitted by motor vehicles – carbon in different chemical forms. What these compounds are exactly and how they affect health are questions that require further research,” Artaxo said.

He added that a consensus is forming in the United States and Europe based on recent research indicating that these emissions are a potential health hazard and should be regulated. Several US states, such as California, have laws requiring a 20%-30% ethanol blend in gasoline, which also helps reduce emissions of ultrafine particulate matter.

Methodology

The data analyzed in the study were collected during the period of January-May 2011, when ethanol prices fluctuated sharply compared with gasoline prices, owing to macroeconomic factors such as variations in the international price of sugar (Brazilian ethanol is made from sugarcane).

Collection was performed at the top of a ten-story building belonging to IF-USP in the western part of São Paulo City. According to Artaxo, the site was chosen because it is relatively distant from the main traffic thoroughfares so that the aerosols there are “older” in the sense that they have already interacted with other substances present in the atmosphere.

“Generally speaking, the pollution we inhale every day at home or at work isn’t what comes out of vehicular exhaust pipes but particles already processed in the atmosphere,” he explained. “For this reason, we chose a site that isn’t directly impacted by primary vehicle emissions.”

The study was conducted during Joel Ferreira de Brito’s postdoctoral research, which Artaxo supervised. The model used to analyze the data was developed by Brazilian economist Alberto Salvo, a professor at the National University of Singapore and first author of the article. Franz Geiger, a chemist at Northwestern University in the US, also collaborated.

“We adapted a sophisticated statistical model originally developed for economic analysis and used here for the first time to analyze the chemistry of atmospheric nanoparticles,” Artaxo said. “The main strength of this tool is that it can work with a large number of variables, such as the presence or absence of rainfall, wind direction, traffic intensity, and levels of ozone, carbon monoxide and other pollutants.”

Analyses were performed before, during and after a sharp fluctuation in ethanol prices leading consumers to switch motor fuels in São Paulo City. While no significant changes were detected in levels of inhalable fine particulate matter (PM2.5 and PM10), the study proved in a real, day-to-day situation that choosing ethanol reduces emissions of ultrafine particles. To date, this phenomenon had only been observed in the laboratory.

“These results reinforce the need for public policies to encourage the use of biofuels, as they clearly show that the public lose in health what they save at the pump when opting for gasoline,” Artaxo said.

In São Paulo, a city with 7 million motor vehicles and the largest urban fleet of flexible-fuel cars, it would be feasible to run all buses on biofuel. “We have the technology for this in Brazil – and at a competitive price,” he said.

The fact that the city’s bus fleet still depends on diesel, Artaxo warned, creates an even worse health hazard in the shape of emissions of black carbon, one of the main components of soot and a pollutant that contributes to global warming. Alongside electricity generation, the transportation sector is the largest emitter of pollutants produced by the burning of fossil fuels.

For Artaxo, incentives for electric, hybrid or biofuel vehicles are vital to reduce greenhouse gas emissions. “By incentivizing biofuels, we could solve several problems at once,” he said. “We could combat climate change, reduce harm to health and foster advances in automotive technology by offering a stimulus for auto makers to develop more economical and efficient cars fueled by ethanol.”

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

Reduced ultrafine particle levels in São Paulo’s atmosphere during shifts from gasoline to ethanol use by Alberto Salvo, Joel Brito, Paulo Artaxo, & Franz M. Geiger. Nature Communications 8, Article number: 77 (2017) doi:10.1038/s41467-017-00041-5 Published online: 18 July 2017

This paper is open access.

Sugar in your bones might be better for you than you think

These days sugar is often  viewed as leading to health problems but there is an instance where it may be useful—bone regeneration. From a June 19, 2017 news item on Nanowerk (Note: A link has been removed),

There hasn’t been a gold standard for how orthopaedic spine surgeons promote new bone growth in patients, but now Northwestern University scientists have designed a bioactive nanomaterial that is so good at stimulating bone regeneration it could become the method surgeons prefer.

While studied in an animal model of spinal fusion, the method for promoting new bone growth could translate readily to humans, the researchers say, where an aging but active population in the U.S. is increasingly receiving this surgery to treat pain due to disc degeneration, trauma and other back problems. Many other procedures could benefit from the nanomaterial, ranging from repair of bone trauma to treatment of bone cancer to bone growth for dental implants.

“Regenerative medicine can improve quality of life by offering less invasive and more successful approaches to promoting bone growth,” said Samuel I. Stupp, who developed the new nanomaterial. “Our method is very flexible and could be adapted for the regeneration of other tissues, including muscle, tendons and cartilage.”

Stupp is director of Northwestern’s Simpson Querrey Institute for BioNanotechnology and the Board of Trustees Professor of Materials Science and Engineering, Chemistry, Medicine and Biomedical Engineering.

For the interdisciplinary study, Stupp collaborated with Dr. Wellington K. Hsu, associate professor of orthopaedic surgery, and Erin L. K. Hsu, research assistant professor of orthopaedic surgery, both at Northwestern University Feinberg School of Medicine. The husband-and-wife team is working to improve clinically employed methods of bone regeneration.

Sugar molecules on the surface of the nanomaterial provide its regenerative power. The researchers studied in vivo the effect of the “sugar-coated” nanomaterial on the activity of a clinically used growth factor, called bone morphogenetic protein 2 (BMP-2). They found the amount of protein needed for a successful spinal fusion was reduced to an unprecedented level: 100 times less of BMP-2 was needed. This is very good news, because the growth factor is known to cause dangerous side effects when used in the amounts required to regenerate high-quality bone, and it is expensive as well.

A June 19, 2017 Northwestern University news release by Megan Fellman, which originated the news item, tells the rest of the story,

Stupp’s biodegradable nanomaterial functions as an artificial extracellular matrix, which mimics what cells in the body usually interact with in their surroundings. BMP-2 activates certain types of stem cells and signals them to become bone cells. The Northwestern matrix, which consists of tiny nanoscale filaments, binds the protein by molecular design in the way that natural sugars bind it in our bodies and then slowly releases it when needed, instead of in one early burst, which can contribute to side effects.

To create the nanostructures, the research team led by Stupp synthesized a specific type of sugar that closely resembles those used by nature to activate BMP-2 when cell signaling is necessary for bone growth. Rapidly moving flexible sugar molecules displayed on the surface of the nanostructures “grab” the protein in a specific spot that is precisely the same one used in biological systems when it is time to deploy the signal. This potentiates the bone-growing signals to a surprising level that surpasses even the naturally occurring sugar polymers in our bodies.

In nature, the sugar polymers are known as sulfated polysaccharides, which have super-complex structures impossible to synthesize at the present time with chemical techniques. Hundreds of proteins in biological systems are known to have specific domains to bind these sugar polymers in order to activate signals. Such proteins include those involved in the growth of blood vessels, cell recruitment and cell proliferation, all very important biologically in tissue regeneration. Therefore, the approach of the Stupp team could be extended to other regenerative targets.

Spinal fusion is a common surgical procedure that joins adjacent vertebra together using a bone graft and growth factors to promote new bone growth, which stabilizes the spine. The bone used in the graft can come from the patient’s pelvis — an invasive procedure — or from a bone bank.

“There is a real need for a clinically efficacious, safe and cost-effective way to form bone,” said Wellington Hsu, a spine surgeon. “The success of this nanomaterial makes me excited that every spine surgeon may one day subscribe to this method for bone graft. Right now, if you poll an audience of spine surgeons, you will get 15 to 20 different answers on what they use for bone graft. We need to standardize choice and improve patient outcomes.”

In the in vivo portion of the study, the nanomaterial was delivered to the spine using a collagen sponge. This is the way surgeons currently deliver BMP-2 clinically to promote bone growth.

The Northwestern research team plans to seek approval from the Food and Drug Administration to launch a clinical trial studying the nanomaterial for bone regeneration in humans.

“We surgeons are looking for optimal carriers for growth factors and cells,” Wellington Hsu said. “With its numerous binding sites, the long filaments of this new nanomaterial is more successful than existing carriers in releasing the growth factor when the body is ready. Timing is critical for success in bone regeneration.”

In the new nanomaterial, the sugars are displayed in a scaffold built from self-assembling molecules known as peptide amphiphiles, first developed by Stupp 15 years ago. These synthetic molecules have been essential in his work on regenerative medicine.

“We focused on bone regeneration to demonstrate the power of the sugar nanostructure to provide a big signaling boost,” Stupp said. “With small design changes, the method could be used with other growth factors for the regeneration of all kinds of tissues. One day we may be able to fully do away with the use of growth factors made by recombinant biotechnology and instead empower the natural ones in our bodies.”

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

Sulfated glycopeptide nanostructures for multipotent protein activation by Sungsoo S. Lee, Timmy Fyrner, Feng Chen, Zaida Álvarez, Eduard Sleep, Danielle S. Chun, Joseph A. Weiner, Ralph W. Cook, Ryan D. Freshman, Michael S. Schallmo, Karina M. Katchko, Andrew D. Schneider, Justin T. Smith, Chawon Yun, Gurmit Singh, Sohaib Z. Hashmi, Mark T. McClendon, Zhilin Yu, Stuart R. Stock, Wellington K. Hsu, Erin L. Hsu, & Samuel I. Stupp. Nature Nanotechnology 12, 821–829 (2017) doi:10.1038/nnano.2017.109 Published online 19 June 2017

This paper is behind a paywall.

‘Origami organs’ for tissue engineering

This is a different approach to tissue engineering and its the consequence of a serendipitous accident.  From an Aug. 7, 2017 Northwestern University news release (also on EurekAlert),

Northwestern Medicine scientists and engineers have invented a range of bioactive “tissue papers” made of materials derived from organs that are thin and flexible enough to even fold into an origami bird. The new biomaterials can potentially be used to support natural hormone production in young cancer patients and aid wound healing.

The tissue papers are made from structural proteins excreted by cells that give organs their form and structure. The proteins are combined with a polymer to make the material pliable.

In the study, individual types of tissue papers were made from ovarian, uterine, kidney, liver, muscle or heart proteins obtained by processing pig and cow organs. Each tissue paper had specific cellular properties of the organ from which it was made.

The article describing the tissue paper and its function will be published Aug. 7 in the journal Advanced Functional Materials.

“This new class of biomaterials has potential for tissue engineering and regenerative medicine as well as drug discovery and therapeutics,” corresponding author Ramille Shah said. “It’s versatile and surgically friendly.”

Shah is an assistant professor of surgery at the Feinberg School of Medicine and an assistant professor of materials science and engineering at McCormick School of Engineering. She also is a member of the Simpson Querrey Institute for BioNanotechnology.

For wound healing, Shah thinks the tissue paper could provide support and the cell signaling needed to help regenerate tissue to prevent scarring and accelerate healing.

The tissue papers are made from natural organs or tissues. The cells are removed, leaving the natural structural proteins – known as the extracellular matrix – that then are dried into a powder and processed into the tissue papers. Each type of paper contains residual biochemicals and protein architecture from its original organ that can stimulate cells to behave in a certain way.

In the lab of reproductive scientist Teresa Woodruff, the tissue paper made from a bovine ovary was used to grow ovarian follicles when they were cultured in vitro. The follicles (eggs and hormone-producing cells) grown on the tissue paper produced hormones necessary for proper function and maturation.

“This could provide another option to restore normal hormone function to young cancer patients who often lose their hormone function as a result of chemotherapy and radiation,” Woodruff, a study coauthor, said.

A strip of the ovarian paper with the follicles could be implanted under the arm to restore hormone production for cancer patients or even women in menopause.

Woodruff is the director of the Oncofertility Consortium and the Thomas J. Watkins Memorial Professor of Obstetrics and Gynecology at Feinberg.

In addition, the tissue paper made from various organs separately supported the growth of adult human stem cells. Scientists placed human bone marrow stem cells on the tissue paper, and all the stem cells attached and multiplied over four weeks.

“That’s a good sign that the paper supports human stem cell growth,” said first author Adam Jakus, who developed the tissue papers. “It’s an indicator that once we start using tissue paper in animal models it will be biocompatible.”

The tissue papers feel and behave much like standard office paper when they are dry, Jakus said. Jakus simply stacks them in a refrigerator or a freezer. He even playfully folded them into an origami bird.

“Even when wet, the tissue papers maintain their mechanical properties and can be rolled, folded, cut and sutured to tissue,” he said.

Jakus was a Hartwell postdoctoral fellow in Shah’s lab for the study and is now chief technology officer and cofounder of the startup company Dimension Inx, LLC, which was also cofounded by Shah. The company will develop, produce and sell 3-D printable materials primarily for medical applications. The Intellectual Property is owned by Northwestern University and will be licensed to Dimension Inx.

An Accidental Spill Sparked Invention

An accidental spill of 3-D printing ink in Shah’s lab by Jakus sparked the invention of the tissue paper. Jakus was attempting to make a 3-D printable ovary ink similar to the other 3-D printable materials he previously developed to repair and regenerate bone, muscle and nerve tissue. When he went to wipe up the spill, the ovary ink had already formed a dry sheet.

“When I tried to pick it up, it felt strong,” Jakus said. “I knew right then I could make large amounts of bioactive materials from other organs. The light bulb went on in my head. I could do this with other organs.”

“It is really amazing that meat and animal by-products like a kidney, liver, heart and uterus can be transformed into paper-like biomaterials that can potentially regenerate and restore function to tissues and organs,” Jakus said. “I’ll never look at a steak or pork tenderloin the same way again.”

For those who like their news in a video,

As someone who once made baklava, that does not look like filo pastry, where an individual sheet is quite thin and rips easily. Enough said.

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

“Tissue Papers” from Organ-Specific Decellularized Extracellular Matrices by Adam E. Jakus, Monica M. Laronda, Alexandra S. Rashedi, Christina M. Robinson, Chris Lee, Sumanas W. Jordan, Kyle E. Orwig, Teresa K. Woodruff, and Ramille N. Shah. Advnaced Functional Materials DOI: 10.1002/adfm.201700992 Version of Record online: 7 AUG 2017

© 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

This paper is behind a paywall.

Ora Sound, a Montréal-based startup, and its ‘graphene’ headphones

For all the excitement about graphene there aren’t that many products as Glenn Zorpette notes in a June 20, 2017 posting about Ora Sound and its headphones on the Nanoclast blog (on the IEEE [Institute of Electrical and Electronics Engineers] website; Note: Links have been removed),

Graphene has long been touted as a miracle material that would deliver everything from tiny, ultralow-power transistors to the vastly long and ultrastrong cable [PDF] needed for a space elevator. And yet, 13 years of graphene development, and R&D expenditures well in the tens of billions of dollars have so far yielded just a handful of niche products. The most notable by far is a line of tennis racquets in which relatively small amounts of graphene are used to stiffen parts of the frame.

Ora Sound, a Montreal-based [Québec, Canada] startup, hopes to change all that. On 20 June [2017], it unveiled a Kickstarter campaign for a new audiophile-grade headphone that uses cones, also known as membranes, made of a form of graphene. “To the best of our knowledge, we are the first company to find a significant, commercially viable application for graphene,” says Ora cofounder Ari Pinkas, noting that the cones in the headphones are 95 percent graphene.

Kickstarter

It should be noted that participating in a Kickstarter campaign is an investment/gamble. I am not endorsing Ora Sound or its products. That said, this does look interesting (from the ORA: The World’s First Graphene Headphones Kickstarter campaign webpage),

ORA GQ Headphones uses nanotechnology to deliver the most groundbreaking audio listening experience. Scientists have long promised that one day Graphene will find its way into many facets of our lives including displays, electronic circuits and sensors. ORA’s Graphene technology makes it one of the first companies to have created a commercially viable application for this Nobel-prize winning material, a major scientific achievement.

The GQ Headphones come equipped with ORA’s patented GrapheneQ™ membranes, providing unparalleled fidelity. The headphones also offer all the features you would expect from a high-end audio product: wired/wireless operation, a gesture control track-pad, a digital MEMS microphone, breathable lambskin leather and an ear-shaped design optimized for sound quality and isolated comfort.

They have produced a slick video to promote their campaign,

At the time of publishing this post, the campaign will run for another eight days and has raised $650,949 CAD. This is more than $500,000 dollars over the company’s original goal of $135,000. I’m sure they’re ecstatic but this success can be a mixed blessing. They have many more people expecting a set of headphones than they anticipated and that can mean production issues.

Further, there appears to be only one member of the team with business experience and his (Ari Pinkas) experience includes marketing strategy for a few years and then founding an online marketplace for teachers. I would imagine Pinkas will be experiencing a very steep learning curve. Hopefully, Helge Seetzen, a member of the company’s advisory board will be able to offer assistance. According to Seetzen’s Wikipedia entry, he is a “… German technologist and businessman known for imaging & multimedia research and commercialization,” as well as, having a Canadian educational background and business experience. The rest of the team and advisory board appear to be academics.

The technology

A March 14, 2017 article by Andy Riga for the Montréal Gazette gives a general description of the technology,

A Montreal startup is counting on technology sparked by a casual conversation between two brothers pursuing PhDs at McGill University.

They were chatting about their disparate research areas — one, in engineering, was working on using graphene, a form of carbon, in batteries; the other, in music, was looking at the impact of electronics on the perception of audio quality.

At first glance, the invention that ensued sounds humdrum.

It’s a replacement for an item you use every day. It’s paper thin, you probably don’t realize it’s there and its design has not changed much in more than a century. Called a membrane or diaphragm, it’s the part of a loudspeaker that vibrates to create the sound from the headphones over your ears, the wireless speaker on your desk, the cellphone in your hand.

Membranes are normally made of paper, Mylar or aluminum.

Ora’s innovation uses graphene, a remarkable material whose discovery garnered two scientists the 2010 Nobel Prize in physics but which has yet to fulfill its promise.

“Because it’s so stiff, our membrane gets better sound quality,” said Robert-Eric Gaskell, who obtained his PhD in sound recording in 2015. “It can produce more sound with less distortion, and the sound that you hear is more true to the original sound intended by the artist.

“And because it’s so light, we get better efficiency — the lighter it is, the less energy it takes.”

In January, the company demonstrated its membrane in headphones at the Consumer Electronics Show, a big trade convention in Las Vegas.

Six cellphone manufacturers expressed interest in Ora’s technology, some of which are now trying prototypes, said Ari Pinkas, in charge of product marketing at Ora. “We’re talking about big cellphone manufacturers — big, recognizable names,” he said.

Technology companies are intrigued by the idea of using Ora’s technology to make smaller speakers so they can squeeze other things, such as bigger batteries, into the limited space in electronic devices, Pinkas said. Others might want to use Ora’s membrane to allow their devices to play music louder, he added.

Makers of regular speakers, hearing aids and virtual-reality headsets have also expressed interest, Pinkas said.

Ora is still working on headphones.

Riga’s article offers a good overview for people who are not familiar with graphene.

Zorpette’s June 20, 2017 posting (on Nanoclast) offers a few more technical details (Note: Links have been removed),

During an interview and demonstration in the IEEE Spectrum offices, Pinkas and Robert-Eric Gaskell, another of the company’s cofounders, explained graphene’s allure to audiophiles. “Graphene has the ideal properties for a membrane,” Gaskell says. “It’s incredibly stiff, very lightweight—a rare combination—and it’s well damped,” which means it tends to quell spurious vibrations. By those metrics, graphene soundly beats all the usual choices: mylar, paper, aluminum, or even beryllium, Gaskell adds.

The problem is making it in sheets large enough to fashion into cones. So-called “pristine” graphene exists as flakes, [emphasis mine] perhaps 10 micrometers across, and a single atom thick. To make larger, strong sheets of graphene, researchers attach oxygen atoms to the flakes, and then other elements to the oxygen atoms to cross-link the flakes and hold them together strongly in what materials scientists call a laminate structure. The intellectual property behind Ora’s advance came from figuring out how to make these structures suitably thick and in the proper shape to function as speaker cones, Gaskell says. In short, he explains, the breakthrough was, “being able to manufacture” in large numbers, “and in any geometery we want.”

Much of the R&D work that led to Ora’s process was done at nearby McGill University, by professor Thomas Szkopek of the Electrical and Computer Engineering department. Szkopek worked with Peter Gaskell, Robert-Eric’s younger brother. Ora is also making use of patents that arose from work done on graphene by the Nguyen Group at Northwestern University, in Evanston, Ill.

Robert-Eric Gaskell and Pinkas arrived at Spectrum with a preproduction model of their headphones, as well as some other headphones for the sake of comparison. The Ora prototype is clearly superior to the comparison models, but that’s not much of a surprise. …

… In the 20 minutes or so I had to audition Ora’s preproduction model, I listened to an assortment of classical and jazz standards and I came away impressed. The sound is precise, with fine details sharply rendered. To my surprise, I was reminded of planar-magnetic type headphones that are now surging in popularity in the upper reaches of the audiophile headphone market. Bass is smooth and tight. Overall, the unit holds up quite well against closed-back models in the $400 to $500 range I’ve listened to from Grado, Bowers & Wilkins, and Audeze.

Ora’s Kickstarter campaign page (Graphene vs GrapheneQ subsection) offers some information about their unique graphene composite,

A TECHNICAL INTRODUCTION TO GRAPHENE

Graphene is a new material, first isolated only 13 years ago. Formed from a single layer of carbon atoms, Graphene is a hexagonal crystal lattice in a perfect honeycomb structure. This fundamental geometry makes Graphene ridiculously strong and lightweight. In its pure form, Graphene is a single atomic layer of carbon. It can be very expensive and difficult to produce in sizes any bigger than small flakes. These challenges have prevented pristine Graphene from being integrated into consumer technologies.

THE GRAPHENEQ™ SOLUTION

At ORA, we’ve spent the last few years creating GrapheneQ, our own, proprietary Graphene-based nanocomposite formulation. We’ve specifically designed and optimized it for use in acoustic transducers. GrapheneQ is a composite material which is over 95% Graphene by weight. It is formed by depositing flakes of Graphene into thousands of layers that are bonded together with proprietary cross-linking agents. Rather than trying to form one, continuous layer of Graphene, GrapheneQ stacks flakes of Graphene together into a laminate material that preserves the benefits of Graphene while allowing the material to be formed into loudspeaker cones.

Scanning Electron Microscope (SEM) Comparison
Scanning Electron Microscope (SEM) Comparison

If you’re interested in more technical information on sound, acoustics, soundspeakers, and Ora’s graphene-based headphones, it’s all there on Ora’s Kickstarter campaign page.

The Québec nanotechnology scene in context and graphite flakes for graphene

There are two Canadian provinces that are heavily invested in nanotechnology research and commercialization efforts. The province of Québec has poured money into their nanotechnology efforts, while the province of Alberta has also invested heavily in nanotechnology, it has also managed to snare additional federal funds to host Canada’s National Institute of Nanotechnology (NINT). (This appears to be a current NINT website or you can try this one on the National Research Council website). I’d rank Ontario as being a third centre with the other provinces being considerably less invested. As for the North, I’ve not come across any nanotechnology research from that region. Finally, as I stumble more material about nanotechnology in Québec than I do for any other province, that’s the reason I rate Québec as the most successful in its efforts.

Regarding graphene, Canada seems to have an advantage. We have great graphite flakes for making graphene. With mines in at least two provinces, Ontario and Québec, we have a ready source of supply. In my first posting (July 25, 2011) about graphite mines here, I had this,

Who knew large flakes could be this exciting? From the July 25, 2011 news item on Nanowerk,

Northern Graphite Corporation has announced that graphene has been successfully made on a test basis using large flake graphite from the Company’s Bissett Creek project in Northern Ontario. Northern’s standard 95%C, large flake graphite was evaluated as a source material for making graphene by an eminent professor in the field at the Chinese Academy of Sciences who is doing research making graphene sheets larger than 30cm2 in size using the graphene oxide methodology. The tests indicated that graphene made from Northern’s jumbo flake is superior to Chinese powder and large flake graphite in terms of size, higher electrical conductivity, lower resistance and greater transparency.

Approximately 70% of production from the Bissett Creek property will be large flake (+80 mesh) and almost all of this will in fact be +48 mesh jumbo flake which is expected to attract premium pricing and be a better source material for the potential manufacture of graphene. The very high percentage of large flakes makes Bissett Creek unique compared to most graphite deposits worldwide which produce a blend of large, medium and small flakes, as well as a large percentage of low value -150 mesh flake and amorphous powder which are not suitable for graphene, Li ion batteries or other high end, high growth applications.

Since then I’ve stumbled across more information about Québec’s mines than Ontario’s  as can be seen:

There are some other mentions of graphite mines in other postings but they are tangential to what’s being featured:

  • (my Oct. 26, 2015 posting about St. Jean Carbon and its superconducting graphene and
  • my Feb. 20, 2015 posting about Nanoxplore and graphene production in Québec; and
  • this Feb. 23, 2015 posting about Grafoid and its sister company, Focus Graphite which gets its graphite flakes from a deposit in the northeastern part of Québec).

 

After reviewing these posts, I’ve begun to wonder where Ora’s graphite flakes come from? In any event, I wish the folks at Ora and their Kickstarter funders the best of luck.

Regrowing bone

The ability to grow bone or bone-like material could change life substantially for people with certain kinds of injuries. Scientists at Northwestern University and the University of Chicago have been able to regrow bone in a skull (according to a March 8, 2017 Northwestern University news release (also on EurekAlert),

A team of researchers repaired a hole in a mouse’s skull by regrowing “quality bone,” a breakthrough that could drastically improve the care of people who suffer severe trauma to the skull or face.

The work by a joint team of Northwestern Engineering and University of Chicago researchers was a resounding success, showing that a potent combination of technologies was able to regenerate the skull bone with supporting blood vessels in just the discrete area needed without developing scar tissue — and more rapidly than with previous methods.

“The results are very exciting,” said Guillermo Ameer, professor of biomedical engineering at Northwestern’s McCormick School of Engineering, and professor of surgery at Feinberg School of Medicine.

Supported by the China Scholarship Council, National Institute of Dental and Craniofacial Research, Chicago Community Trust, and National Center for Advancing Translational Sciences, the research was published last week in the journal PLOS One. Russell Reid, associate professor of surgery at the University of Chicago Medical Center, is the article’s corresponding author. Reid, his long-time collaborator Dr. Tong-Chuan He, and colleagues in Hyde Park brought the surgical and biological knowledge and skills. Zari P. Dumanian, affiliated with the medical center’s surgery department, was the paper’s first author.

“This project was a true collaborative team effort in which our Regenerative Engineering Laboratory provided the biomaterials expertise,” Ameer said.

Injuries or defects in the skull or facial bones are very challenging to treat, often requiring the surgeon to graft bone from the patient’s pelvis, ribs, or elsewhere, a painful procedure in itself. Difficulties increase if the injury area is large or if the graft needs to be contoured to the angle of the jaw or the cranial curve.

But if all goes well with this new approach, it may make painful bone grafting obsolete.

In the experiment, the researchers harvested skull cells from the mouse and engineered them to produce a potent protein to promote bone growth. They then used Ameer’s hydrogel, which acted like a temporary scaffolding, to deliver and contain these cells to the affected area. It was the combination of all three technologies that proved so successful, Ameer said.

Using calvaria or skull cells from the subject meant the body didn’t reject those cells.

The protein, BMP9, has been shown to promote bone cell growth more rapidly than other types of BMPs. Importantly, BMP9 also appeared to improve the creation of blood vessels in the area. Being able to safely deliver skull cells that are capable of rapidly regrowing bone in the affected site, in vivo as opposed to using them to grow bone in the laboratory, which would take a very long time, promises a therapy that might be more “surgeon friendly, if you will, and not too complicated to scale up for the patients,” Ameer said.

The scaffolding developed in Ameer’s laboratory, which is a material based on citric acid and called PPCN-g, is a liquid that when warmed to body temperature becomes a gel-like elastic material. “When applied, the liquid, which contains cells capable of producing bone, will conform to the shape of the bone defect to make a perfect fit,” Ameer said. “It then stays in place as a gel, localizing the cells to the site for the duration of the repair.” As the bone regrows, the PPCN-g is reabsorbed by the body.

“What we found is that these cells make natural-looking bone in the presence of the PPCN-g,” Ameer said. “The new bone is very similar to normal bone in that location.”

In fact, the three-part method was successful on a number of fronts: The regenerated bone was better quality, the bone growth was contained to the area defined by the scaffolding, the area healed much more quickly, and the new and old bone were continuous with no scar tissue.

The potential, if the procedure can be adapted to treat people that suffered trauma from car accidents or aggressive cancers that have affected the skull or face, would be huge, and give surgeons a much-sought-after option.

“The reconstruction procedure is a lot easier when you can harvest a few cells, make them produce the BMP9 protein, mix them in the PPCN-g solution, and apply it to the bone defect site to jump-start the new bone growth process where you want it.” Ameer said.

Ameer cautioned that the technology is years away to being used in humans, but added, “We did show proof of concept that we can heal large defects in the skull that would normally not heal on their own using a protein, cells and a new material that come together in a completely new way. Our team is very excited about these findings and the future of reconstructive surgery.”

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

Repair of critical sized cranial defects with BMP9-transduced calvarial cells delivered in a thermoresponsive scaffold by Zari P. Dumanian, Viktor Tollemar, Jixing Ye, Minpeng Lu, Yunxiao Zhu, Junyi Liao, Guillermo A. Ameer, Tong-Chuan He, Russell R. Reid. PLOS http://dx.doi.org/10.1371/journal.pone.0172327 Published: March 1, 2017

This is an open access paper.

The inside scoop on beetle exoskeletons

In the past I’ve covered work on the Namib beetle and its bumps which allow it to access condensation from the air in one of the hottest places on earth and work on jewel beetles and how their structural colo(u)r is derived. Now, there’s research into a beetle’s body armor from the University of Nebraska-Lincoln according to a Feb. 22, 2017 news item on ScienceDaily,

Beetles wear a body armor that should weigh them down — think medieval knights and turtles. In fact, those hard shells protecting delicate wings are surprisingly light, allowing even flight.

Better understanding the structure and properties of beetle exoskeletons could help scientists engineer lighter, stronger materials. Such materials could, for example, reduce gas-guzzling drag in vehicles and airplanes and reduce the weight of armor, lightening the load for the 21st-century knight.

But revealing exoskeleton architecture at the nanoscale has proven difficult. Nebraska’s Ruiguo Yang, assistant professor of mechanical and materials engineering, and his colleagues found a way to analyze the fibrous nanostructure. …

A Feb. 22, 2017 University of Nebraska-Lincoln news release by Gillian Klucas (also on EurekAlert), which originated the news item, describes skeletons and the work in more detail,

The lightweight exoskeleton is composed of chitin fibers just around 20 nanometers in diameter (a human hair measures approximately 75,000 nanometers in diameter) and packed and piled into layers that twist in a spiral, like a spiral staircase. The small diameter and helical twisting, known as Bouligand, make the structure difficult to analyze.

Yang and his team developed a method of slicing down the spiral to reveal a surface of cross-sections of fibers at different orientations. From that viewpoint, the researchers were able to analyze the fibers’ mechanical properties with the aid of an atomic force microscope. This type of microscope applies a tiny force to a test sample, deforms the sample and monitors the sample’s response. Combining the experimental procedure and theoretical analysis, the researchers were able to reveal the nanoscale architecture of the exoskeleton and the material properties of the nanofibers.

Yang holds a piece of the atomic force microscope used to measure the beetle's surface. A small wire can barely be seen in the middle of the piece. Unseen is a two-nano-size probe attached to the wire, which does the actual measuring.

Craig Chandler | University Communication

Yang holds a piece of the atomic force microscope used to measure the beetle’s surface. A small wire can barely be seen in the middle of the piece. Unseen is a two-nano-size probe attached to the wire, which does the actual measuring.

They made their discoveries in the common figeater beetle, Cotinis mutabilis, a metallic green native of the western United States. But the technique can be used on other beetles and hard-shelled creatures and might also extend to artificial materials with fibrous structures, Yang said.

Comparing beetles with differing demands on their exoskeletons, such as defending against predators or environmental damage, could lead to evolutionary insights as well as a better understanding of the relationship between structural features and their properties.

Yang’s co-authors are Alireza Zaheri and Horacio Espinosa of Northwestern University; Wei Gao of the University of Texas at San Antonio; and Cheryl Hayashi of the University of California, Riverside.

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

Exoskeletons: AFM Identification of Beetle Exocuticle: Bouligand Structure and Nanofiber Anisotropic Elastic Properties by Ruiguo Yang, Alireza Zaheri,Wei Gao, Charely Hayashi, Horacio D. Espinosa. Adv. Funct. Mater. vol. 27 (6) 2017 DOI: 10.1002/adfm.201770031 First published: 8 February 2017

This paper is behind a paywall.

A DNA switch for new electronic applications

I little dreamed when reading “The Double Helix : A Personal Account of the Discovery of the Structure of DNA” by James Watson that DNA (deoxyribonucleic acid) would one day become just another material for scientists to manipulate. A Feb. 20, 2017 news item on ScienceDaily describes the use of DNA as a material in electronics applications,

DNA, the stuff of life, may very well also pack quite the jolt for engineers trying to advance the development of tiny, low-cost electronic devices.

Much like flipping your light switch at home — only on a scale 1,000 times smaller than a human hair — an ASU [Arizona State University]-led team has now developed the first controllable DNA switch to regulate the flow of electricity within a single, atomic-sized molecule. The new study, led by ASU Biodesign Institute researcher Nongjian Tao, was published in the advanced online journal Nature Communications.

DNA, the stuff of life, may very well also pack quite the jolt for engineers trying to advance the development of tiny, low-cost electronic devices. Courtesy: ASU

A Feb. 20, 2017 ASU news release (also on EurekAlert), which originated the news item, provides more detail,

“It has been established that charge transport is possible in DNA, but for a useful device, one wants to be able to turn the charge transport on and off. We achieved this goal by chemically modifying DNA,” said Tao, who directs the Biodesign Center for Bioelectronics and Biosensors and is a professor in the Fulton Schools of Engineering. “Not only that, but we can also adapt the modified DNA as a probe to measure reactions at the single-molecule level. This provides a unique way for studying important reactions implicated in disease, or photosynthesis reactions for novel renewable energy applications.”

Engineers often think of electricity like water, and the research team’s new DNA switch acts to control the flow of electrons on and off, just like water coming out of a faucet.

Previously, Tao’s research group had made several discoveries to understand and manipulate DNA to more finely tune the flow of electricity through it. They found they could make DNA behave in different ways — and could cajole electrons to flow like waves according to quantum mechanics, or “hop” like rabbits in the way electricity in a copper wire works —creating an exciting new avenue for DNA-based, nano-electronic applications.

Tao assembled a multidisciplinary team for the project, including ASU postdoctoral student Limin Xiang and Li Yueqi performing bench experiments, Julio Palma working on the theoretical framework, with further help and oversight from collaborators Vladimiro Mujica (ASU) and Mark Ratner (Northwestern University).

To accomplish their engineering feat, Tao’s group, modified just one of DNA’s iconic double helix chemical letters, abbreviated as A, C, T or G, with another chemical group, called anthraquinone (Aq). Anthraquinone is a three-ringed carbon structure that can be inserted in between DNA base pairs but contains what chemists call a redox group (short for reduction, or gaining electrons or oxidation, losing electrons).

These chemical groups are also the foundation for how our bodies’ convert chemical energy through switches that send all of the electrical pulses in our brains, our hearts and communicate signals within every cell that may be implicated in the most prevalent diseases.

The modified Aq-DNA helix could now help it perform the switch, slipping comfortably in between the rungs that make up the ladder of the DNA helix, and bestowing it with a new found ability to reversibly gain or lose electrons.

Through their studies, when they sandwiched the DNA between a pair of electrodes, they careful [sic] controlled their electrical field and measured the ability of the modified DNA to conduct electricity. This was performed using a staple of nano-electronics, a scanning tunneling microscope, which acts like the tip of an electrode to complete a connection, being repeatedly pulled in and out of contact with the DNA molecules in the solution like a finger touching a water droplet.

“We found the electron transport mechanism in the present anthraquinone-DNA system favors electron “hopping” via anthraquinone and stacked DNA bases,” said Tao. In addition, they found they could reversibly control the conductance states to make the DNA switch on (high-conductance) or switch-off (low conductance). When anthraquinone has gained the most electrons (its most-reduced state), it is far more conductive, and the team finely mapped out a 3-D picture to account for how anthraquinone controlled the electrical state of the DNA.

For their next project, they hope to extend their studies to get one step closer toward making DNA nano-devices a reality.

“We are particularly excited that the engineered DNA provides a nice tool to examine redox reaction kinetics, and thermodynamics the single molecule level,” said Tao.

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

I last featured Tao’s work with DNA in an April 20, 2015 posting.

Gate-controlled conductance switching in DNA by Limin Xiang, Julio L. Palma, Yueqi Li, Vladimiro Mujica, Mark A. Ratner, & Nongjian Tao.  Nature Communications 8, Article number: 14471 (2017)  doi:10.1038/ncomms14471 Published online: 20 February 2017

This paper is open access.

Nominations open for Kabiller Prizes in Nanoscience and Nanomedicine ($250,000 for visionary researcher and $10,000 for young investigator)

For a change I can publish something that doesn’t have a deadline in three days or less! Without more ado (from a Feb. 20, 2017 Northwestern University news release by Megan Fellman [h/t Nanowerk’s Feb. 20, 2017 news item]),

Northwestern University’s International Institute for Nanotechnology (IIN) is now accepting nominations for two prestigious international prizes: the $250,000 Kabiller Prize in Nanoscience and Nanomedicine and the $10,000 Kabiller Young Investigator Award in Nanoscience and Nanomedicine.

The deadline for nominations is May 15, 2017. Details are available on the IIN website.

“Our goal is to recognize the outstanding accomplishments in nanoscience and nanomedicine that have the potential to benefit all humankind,” said David G. Kabiller, a Northwestern trustee and alumnus. He is a co-founder of AQR Capital Management, a global investment management firm in Greenwich, Connecticut.

The two prizes, awarded every other year, were established in 2015 through a generous gift from Kabiller. Current Northwestern-affiliated researchers are not eligible for nomination until 2018 for the 2019 prizes.

The Kabiller Prize — the largest monetary award in the world for outstanding achievement in the field of nanomedicine — celebrates researchers who have made the most significant contributions to the field of nanotechnology and its application to medicine and biology.

The Kabiller Young Investigator Award recognizes young emerging researchers who have made recent groundbreaking discoveries with the potential to make a lasting impact in nanoscience and nanomedicine.

“The IIN at Northwestern University is a hub of excellence in the field of nanotechnology,” said Kabiller, chair of the IIN executive council and a graduate of Northwestern’s Weinberg College of Arts and Sciences and Kellogg School of Management. “As such, it is the ideal organization from which to launch these awards recognizing outstanding achievements that have the potential to substantially benefit society.”

Nanoparticles for medical use are typically no larger than 100 nanometers — comparable in size to the molecules in the body. At this scale, the essential properties (e.g., color, melting point, conductivity, etc.) of structures behave uniquely. Researchers are capitalizing on these unique properties in their quest to realize life-changing advances in the diagnosis, treatment and prevention of disease.

“Nanotechnology is one of the key areas of distinction at Northwestern,” said Chad A. Mirkin, IIN director and George B. Rathmann Professor of Chemistry in Weinberg. “We are very grateful for David’s ongoing support and are honored to be stewards of these prestigious awards.”

An international committee of experts in the field will select the winners of the 2017 Kabiller Prize and the 2017 Kabiller Young Investigator Award and announce them in September.

The recipients will be honored at an awards banquet Sept. 27 in Chicago. They also will be recognized at the 2017 IIN Symposium, which will include talks from prestigious speakers, including 2016 Nobel Laureate in Chemistry Ben Feringa, from the University of Groningen, the Netherlands.

2015 recipient of the Kabiller Prize

The winner of the inaugural Kabiller Prize, in 2015, was Joseph DeSimone the Chancellor’s Eminent Professor of Chemistry at the University of North Carolina at Chapel Hill and the William R. Kenan Jr. Distinguished Professor of Chemical Engineering at North Carolina State University and of Chemistry at UNC-Chapel Hill.

DeSimone was honored for his invention of particle replication in non-wetting templates (PRINT) technology that enables the fabrication of precisely defined, shape-specific nanoparticles for advances in disease treatment and prevention. Nanoparticles made with PRINT technology are being used to develop new cancer treatments, inhalable therapeutics for treating pulmonary diseases, such as cystic fibrosis and asthma, and next-generation vaccines for malaria, pneumonia and dengue.

2015 recipient of the Kabiller Young Investigator Award

Warren Chan, professor at the Institute of Biomaterials and Biomedical Engineering at the University of Toronto, was the recipient of the inaugural Kabiller Young Investigator Award, also in 2015. Chan and his research group have developed an infectious disease diagnostic device for a point-of-care use that can differentiate symptoms.

BTW, Warren Chan, winner of the ‘Young Investigator Award’, and/or his work have been featured here a few times, most recently in a Nov. 1, 2016 posting, which is mostly about another award he won but also includes links to some his work including my April 27, 2016 post about the discovery that fewer than 1% of nanoparticle-based drugs reach their destination.

Nanomechanics for deciphering beetle exoskeletons

Beetles carry remarkably light yet strong armor in the form of their exoskeletons and a research team at Northwestern University (US) is looking to those beetle exoskeletons for inspiration according to a Jan. 11, 2017 news item on ScienceDaily,

What can a beetle tell us about good design principles? Quite a lot, actually.

Many insects and crustaceans possess hard, armor-like exoskeletons that, in theory, should weigh the creatures down. But, instead, the exoskeletons are surprisingly light — even allowing the armor-wearing insects, like the beetle, to fly.

Northwestern Engineering’s Horacio D. Espinosa and his group are working to understand the underlying design principles and mechanical properties that result in structures with these unique, ideal properties. This work could ultimately uncover information that could guide the design and manufacturing of new and improved artificial materials by emulating these time-tested natural patterns, a process known as bio-mimicry.

Supported by the Air Force Office of Scientific Research’s Multidisciplinary University Research Initiative (MURI), the research was featured on the cover of Advanced Functional Materials. Postdoctoral fellows Ruiguo Yang and Wei Gao and graduate student Alireza Zaheri, all members of Espinosa’s laboratory, were co-first authors of the paper. Cheryl Hayashi, professor of biology at the University of California, Riverside, was also a co-author.

A Jan. 11, 2017 Northwestern University news release, which originated the news item, expands on the theme,

Though there are more than a million species of beetles, the team is first studying the exoskeleton of the Cotinis mutabilis, a field crop pest beetle native to the western United States. Like all insects and crustaceans, its exoskeleton is composed of twisted plywood structures, known as Bouligand structures, which help protect against predators. Fibers in this Bouligand structure are bundles of chitin polymer chains wrapped with proteins. In this chain structure, each fiber has a higher density along the length than along the transverse.

“It is very challenging to characterize the properties of such fibers given that they are directionally dependent and have a small diameter of just 20 nanometers,” said Espinosa, the James N. and Nancy J. Farley Professor in Manufacturing and Entrepreneurship at Northwestern’s McCormick School of Engineering. “We had to develop a novel characterization method by taking advantage of the spatial distribution of fibers in the Bouligand structure.”

To meet this challenge, Espinosa and his team employed a creative way to identify the geometry and material properties of the fibers that comprise the exoskeleton. They cut the Bouligand structure along a plane, resulting in a surface composed of closely packed cross-sections of fibers with different orientations. They were then able to analyze the mechanics of the fibers.

“With more than a million species, which greatly vary from each other in taxomic relatedness, size, and ecology, the beetle is the largest group of insects,” Hayashi said. “What makes this research exciting is that the methods applied to the Cotinis mutabilis beetle exoskeleton can be extended to other beetle species.”

By correlating the mechanical properties with the exoskeleton geometries from diverse beetle species, Espinosa and his team plan to gain insight into natural selection and better understand structure-function-properties relationships.

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

AFM Identification of Beetle Exocuticle: Bouligand Structure and Nanofiber Anisotropic Elastic Properties by Ruiguo Yang, Alireza Zaheri, Wei Gao, Cheryl Hayashi, and Horacio D. Espinosa. Advanced Functional Materials DOI: 10.1002/adfm.201603993 Version of Record online: 27 DEC 2016

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

This paper is behind a paywall.

Nanorods as multistate switches

This research goes beyond the binary (0 or 1) and to an analog state that resembles quantum states. Fascinating, yes? An Oct. 10, 2016 news item on phys.org tells more,

Rice University scientists have discovered how to subtly change the interior structure of semi-hollow nanorods in a way that alters how they interact with light, and because the changes are reversible, the method could form the basis of a nanoscale switch with enormous potential.

“It’s not 0-1, it’s 1-2-3-4-5-6-7-8-9-10,” said Rice materials scientist Emilie Ringe, lead scientist on the project, which is detailed in the American Chemical Society journal Nano Letters. “You can differentiate between multiple plasmonic states in a single particle. That gives you a kind of analog version of quantum states, but on a larger, more accessible scale.”

Ringe and colleagues used an electron beam to move silver from one location to another inside gold-and-silver nanoparticles, something like a nanoscale Etch A Sketch. The result is a reconfigurable optical switch that may form the basis for a new type of multiple-state computer memory, sensor or catalyst.

An Oct. 10, 2016 Rice University news release, which originated the news item, describes the work in additional detail,

At about 200 nanometers long, 500 of the metal rods placed end-to-end would span the width of a human hair. However, they are large in comparison with modern integrated circuits. Their multistate capabilities make them more like reprogrammable bar codes than simple memory bits, she said.

“No one has been able to reversibly change the shape of a single particle with the level of control we have, so we’re really excited about this,” Ringe said.

Altering a nanoparticle’s internal structure also alters its external plasmonic response. Plasmons are the electrical ripples that propagate across the surface of metallic materials when excited by light, and their oscillations can be easily read with a spectrometer — or even the human eye — as they interact with visible light.

The Rice researchers found they could reconfigure nanoparticle cores with pinpoint precision. That means memories made of nanorods need not be merely on-off, Ringe said, because a particle can be programmed to emit many distinct plasmonic patterns.

The discovery came about when Ringe and her team, which manages Rice’s advanced electron microscopy lab, were asked by her colleague and co-author Denis Boudreau, a professor at Laval University in Quebec, to characterize hollow nanorods made primarily of gold but containing silver.

“Most nanoshells are leaky,” Ringe said. “They have pinholes. But we realized these nanorods were defect-free and contained pockets of water that were trapped inside when the particles were synthesized. We thought: We have something here.”

Ringe and the study’s lead author, Rice research scientist Sadegh Yazdi, quickly realized how they might manipulate the water. “Obviously, it’s difficult to do chemistry there, because you can’t put molecules into a sealed nanoshell. But we could put electrons in,” she said.

Focusing a subnanometer electron beam on the interior cavity split the water and inserted solvated electrons – free electrons that can exist in a solution. “The electrons reacted directly with silver ions in the water, drawing them to the beam to form silver,” Ringe said. The now-silver-poor liquid moved away from the beam, and its silver ions were replenished by a reaction of water-splitting byproducts with the solid silver in other parts of the rod.

“We actually were moving silver in the solution, reconfiguring it,” she said. “Because it’s a closed system, we weren’t losing anything and we weren’t gaining anything. We were just moving it around, and could do so as many times as we wished.”

The researchers were then able to map the plasmon-induced near-field properties without disturbing the internal structure — and that’s when they realized the implications of their discovery.

“We made different shapes inside the nanorods, and because we specialize in plasmonics, we mapped the plasmons and it turned out to have a very nice effect,” Ringe said. “We basically saw different electric-field distributions at different energies for different shapes.” Numerical results provided by collaborators Nicolas Large of the University of Texas at San Antonio and George Schatz of Northwestern University helped explain the origin of the modes and how the presence of a water-filled pocket created a multitude of plasmons, she said.

The next challenge is to test nanoshells of other shapes and sizes, and to see if there are other ways to activate their switching potentials. Ringe suspects electron beams may remain the best and perhaps only way to catalyze reactions inside particles, and she is hopeful.

“Using an electron beam is actually not as technologically irrelevant as you might think,” she said. “Electron beams are very easy to generate. And yes, things need to be in vacuum, but other than that, people have generated electron beams for nearly 100 years. I’m sure 40 years ago people were saying, ‘You’re going to put a laser in a disk reader? That’s crazy!’ But they managed to do it.

“I don’t think it’s unfeasible to miniaturize electron-beam technology. Humans are good at moving electrons and electricity around. We figured that out a long time ago,” Ringe said.

The research should trigger the imaginations of scientists working to create nanoscale machines and processes, she said.

“This is a reconfigurable unit that you can access with light,” she said. “Reading something with light is much faster than reading with electrons, so I think this is going to get attention from people who think about dynamic systems and people who think about how to go beyond current nanotechnology. This really opens up a new field.”

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

Reversible Shape and Plasmon Tuning in Hollow AgAu Nanorods by Sadegh Yazdi, Josée R. Daniel, Nicolas Large, George C. Schatz, Denis Boudreau, and Emilie Ringe. Nano Lett., Article ASAP DOI: 10.1021/acs.nanolett.6b02946 Publication Date (Web): October 5, 2016

Copyright © 2016 American Chemical Society

This paper is behind a paywall.

The researchers have made this video available for the public,