# Physicists name and codify new field in nanotechnology: ‘electron quantum metamaterials’

### UC Riverside’s Nathaniel Gabor and colleague formulate a vision for the field in a perspective article

Courtesy: University of California at Riverside

Bravo to whomever put the image of a field together together with a subhead that includes the phrases ‘vision for a field’ and ‘perspective article’. It’s even better if you go to the November 5, 2018 University of California at Riverside (UCR) news release (also on EurekAlert) by Iqbal Pittalwala to see the original format,

When two atomically thin two-dimensional layers are stacked on top of each other and one layer is made to rotate against the second layer, they begin to produce patterns — the familiar moiré patterns — that neither layer can generate on its own and that facilitate the passage of light and electrons, allowing for materials that exhibit unusual phenomena. For example, when two graphene layers are overlaid and the angle between them is 1.1 degrees, the material becomes a superconductor.

“It’s a bit like driving past a vineyard and looking out the window at the vineyard rows. Every now and then, you see no rows because you’re looking directly along a row,” said Nathaniel Gabor, an associate professor in the Department of Physics and Astronomy at the University of California, Riverside. “This is akin to what happens when two atomic layers are stacked on top of each other. At certain angles of twist, everything is energetically allowed. It adds up just right to allow for interesting possibilities of energy transfer.”

This is the future of new materials being synthesized by twisting and stacking atomically thin layers, and is still in the “alchemy” stage, Gabor added. To bring it all under one roof, he and physicist Justin C. W. Song of Nanyang Technological University, Singapore, have proposed this field of research be called “electron quantum metamaterials” and have just published a perspective article in Nature Nanotechnology.

“We highlight the potential of engineering synthetic periodic arrays with feature sizes below the wavelength of an electron. Such engineering allows the electrons to be manipulated in unusual ways, resulting in a new range of synthetic quantum metamaterials with unconventional responses,” Gabor said.

Metamaterials are a class of material engineered to produce properties that do not occur naturally. Examples include optical cloaking devices and super-lenses akin to the Fresnel lens that lighthouses use. Nature, too, has adopted such techniques – for example, in the unique coloring of butterfly wings – to manipulate photons as they move through nanoscale structures.

“Unlike photons that scarcely interact with each other, however, electrons in subwavelength structured metamaterials are charged, and they strongly interact,” Gabor said. “The result is an enormous variety of emergent phenomena and radically new classes of interacting quantum metamaterials.”

Gabor and Song were invited by Nature Nanotechnology to write a review paper. But the pair chose to delve deeper and lay out the fundamental physics that may explain much of the research in electron quantum metamaterials. They wrote a perspective paper instead that envisions the current status of the field and discusses its future.

“Researchers, including in our own labs, were exploring a variety of metamaterials but no one had given the field even a name,” said Gabor, who directs the Quantum Materials Optoelectronics lab at UCR. “That was our intent in writing the perspective. We are the first to codify the underlying physics. In a way, we are expressing the periodic table of this new and exciting field. It has been a herculean task to codify all the work that has been done so far and to present a unifying picture. The ideas and experiments have matured, and the literature shows there has been rapid progress in creating quantum materials for electrons. It was time to rein it all in under one umbrella and offer a road map to researchers for categorizing future work.”

In the perspective, Gabor and Song collect early examples in electron metamaterials and distil emerging design strategies for electronic control from them. They write that one of the most promising aspects of the new field occurs when electrons in subwavelength-structure samples interact to exhibit unexpected emergent behavior.

“The behavior of superconductivity in twisted bilayer graphene that emerged was a surprise,” Gabor said. “It shows, remarkably, how electron interactions and subwavelength features could be made to work together in quantum metamaterials to produce radically new phenomena. It is examples like this that paint an exciting future for electronic metamaterials. Thus far, we have only set the stage for a lot of new work to come.”

Gabor, a recipient of a Cottrell Scholar Award and a Canadian Institute for Advanced Research Azrieli Global Scholar Award, was supported by the Air Force Office of Scientific Research Young Investigator Program and a National Science Foundation Division of Materials Research CAREER award.

There is a video illustrating the ideas which is embedded in a November 5, 2018 news item on phys.oirg,

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

Electron quantum metamaterials in van der Waals heterostructures by Justin C. W. Song & Nathaniel M. Gabor. Nature Nanotechnology, volume 13, pages986–993 (2018) DOI: https://doi.org/10.1038/s41565-018-0294-9 Published: 05 November 2018

This paper is behind a paywall.

# “Breaking Me Softly” at the nanoscale

“Breaking Me Softly” sounds like a song title but in this case the phrase as been coined to describe a new technique for controlling materials at the nanoscale according to a June 6, 2016 news item on ScienceDaily,

A finding by a University of Central Florida researcher that unlocks a means of controlling materials at the nanoscale and opens the door to a new generation of manufacturing is featured online in the journal Nature.

Using a pair of pliers in each hand and gradually pulling taut a piece of glass fiber coated in plastic, associate professor Ayman Abouraddy found that something unexpected and never before documented occurred — the inner fiber fragmented in an orderly fashion.

“What we expected to see happen is NOT what happened,” he said. “While we thought the core material would snap into two large pieces, instead it broke into many equal-sized pieces.”

He referred to the technique in the Nature article title as “Breaking Me Softly.”

A June 6, 2016 University of Central Florida (UCF) news release (also on EurekAlert) by Barbara Abney, which originated the news item, expands on the theme,

The process of pulling fibers to force the realignment of the molecules that hold them together, known as cold drawing, has been the standard for mass production of flexible fibers like plastic and nylon for most of the last century.

Abouraddy and his team have shown that the process may also be applicable to multi-layered materials, a finding that could lead to the manufacturing of a new generation of materials with futuristic attributes.

“Advanced fibers are going to be pursuing the limits of anything a single material can endure today,” Abouraddy said.

For example, packaging together materials with optical and mechanical properties along with sensors that could monitor such vital sign as blood pressure and heart rate would make it possible to make clothing capable of transmitting vital data to a doctor’s office via the Internet.

The ability to control breakage in a material is critical to developing computerized processes for potential manufacturing, said Yuanli Bai, a fracture mechanics specialist in UCF’s College of Engineering and Computer Science.

Abouraddy contacted Bai, who is a co-author on the paper, about three years ago and asked him to analyze the test results on a wide variety of materials, including silicon, silk, gold and even ice.

He also contacted Robert S. Hoy, a University of South Florida physicist who specializes in the properties of materials like glass and plastic, for a better understanding of what he found.

Hoy said he had never seen the phenomena Abouraddy was describing, but that it made great sense in retrospect.

The research takes what has traditionally been a problem in materials manufacturing and turned it into an asset, Hoy said.

“Dr. Abouraddy has found a new application of necking” –  a process that occurs when cold drawing causes non-uniform strain in a material, Hoy said.  “Usually you try to prevent necking, but he exploited it to do something potentially groundbreaking.”

The necking phenomenon was discovered decades ago at DuPont and ushered in the age of textiles and garments made of synthetic fibers.

Abouraddy said that cold-drawing is what makes synthetic fibers like nylon and polyester useful. While those fibers are initially brittle, once cold-drawn, the fibers toughen up and become useful in everyday commodities. This discovery at DuPont at the end of the 1920s ushered in the age of textiles and garments made of synthetic fibers.

Only recently have fibers made of multiple materials become possible, he said.  That research will be the centerpiece of a $317 Million U.S. Department of Defense program focused on smart fibers that Abouraddy and UCF will assist with. The Revolutionary Fibers and Textiles Manufacturing Innovation Institute (RFT-MII), led by the Massachusetts Institute of Technology, will incorporate research findings published in the Nature paper, Abouraddy said. The implications for manufacturing of the smart materials of the future are vast. By controlling the mechanical force used to pull the fiber and therefore controlling the breakage patterns, materials can be developed with customized properties allowing them to interact with each other and eternal forces such as the sun (for harvesting energy) and the internet in customizable ways. A co-author on the paper, Ali P. Gordon, an associate professor in the Department of Mechanical & Aerospace Engineering and director of UCF’s Mechanics of Materials Research Group said that the finding is significant because it shows that by carefully controlling the loading condition imparted to the fiber, materials can be developed with tailored performance attributes. “Processing-structure-property relationships need to be strategically characterized for complex material systems. By combining experiments, microscopy, and computational mechanics, the physical mechanisms of the fragmentation process were more deeply understood,” Gordon said. Abouraddy teamed up with seven UCF scientists from the College of Optics & Photonics and the College of Engineering & Computer Science (CECS) to write the paper. Additional authors include one researcher each from the Massachusetts Institute of Technology, Nanyang Technological University in Singapore and the University of South Florida. Here’s a link to and a citation for the paper, Controlled fragmentation of multimaterial fibres and films via polymer cold-drawing by Soroush Shabahang, Guangming Tao, Joshua J. Kaufman, Yangyang Qiao, Lei Wei, Thomas Bouchenot, Ali P. Gordon, Yoel Fink, Yuanli Bai, Robert S. Hoy & Ayman F. Abouraddy. Nature (2016) doi:10.1038/nature17980 Published online 06 June 2016 This paper is behind a paywall. # Observing nanoparticle therapeutics interact with blood in real time Sadly, there are no images showing nanoparticle therapeutics interacting with blood or anything else for that matter to illustrate this story but perhaps the insights offered should suffice. From Sept. 15, 2015 news item on Nanowerk, Researchers at the National University of Singapore (NUS) have developed a technique to observe, in real time, how individual blood components interact and modify advanced nanoparticle therapeutics. The method, developed by an interdisciplinary team consisting clinician-scientist Assistant Professor Chester Lee Drum of the Department of Medicine at the NUS Yong Loo Lin School of Medicine, Professor T. Venky Venkatesan, Director of NUS Nanoscience and Nanotechnology Institute, and Assistant Professor James Kah of the Department of Biomedical Engineering at the NUS Faculty of Engineering, helps guide the design of future nanoparticles to interact in concert with human blood components, thus avoiding unwanted side effects. A Sept. 15, 2015 NUS press release, which originated the news item, describes the research in more specific detail, With their small size and multiple functionalities, nanoparticles have attracted intense attention as both diagnostic and drug delivery systems. However, within minutes of being delivered into the bloodstream, nanoparticles are covered with a shell of serum proteins, also known as a protein ‘corona’. “The binding of serum proteins can profoundly change the behaviour of nanoparticles, at times leading to rapid clearance by the body and a diminished clinical outcome,” said Asst Prof Kah. Existing methods such as mass spectroscopy and diffusional radius estimation, although useful for studying important nanoparticle parameters, are unable to provide detailed, real-time binding kinetics. Novel method to understand nano-bio interactions The NUS team, together with external collaborator Professor Bo Liedberg from the Nanyang Technological University, showed highly reproducible kinetics for the binding between gold nanoparticles and the four most common serum proteins: human serum albumin, fibrinogen, apolipoprotein A-1, and polyclonal IgG. “What was remarkable about this project was the initiative taken by Abhijeet Patra, my graduate student from NUS Graduate School for Integrative Sciences and Engineering, in conceptualising the problem, and bringing together the various teams in NUS and beyond to make this a successful programme,” said Prof Venkatesan. “The key development is the use of a new technique using surface plasmon resonance (SPR) technology to measure the protein corona formed when common proteins in the bloodstream bind to nanoparticles,” he added. The researchers first immobilised the gold nanoparticles to the surface of a SPR sensor chip with a linker molecule. The chip was specially modified with an alginate polymer layer which both provided a negative charge and active sites for ligand immobilisation, and prevented non-specific binding. Using a 6 x 6 microfluidic channel array, they studied up to 36 nanoparticle-protein interactions in a single experiment, running test samples alongside experimental controls. “Reproducibility and reliability have been a bottleneck in the studies of protein coronas,” said Mr Abhijeet Patra. “The quality and reliability of the data depends most importantly upon the design of good control experiments. Our multiplexed SPR setup was therefore key to ensuring the reliability of our data.” Testing different concentrations of each of the four proteins, the team found that apolipoprotein A-1 had the highest binding affinity for the gold nanoparticle surface, with an association constant almost 100 times that of the lowest affinity protein, polyclonal IgG. “Our results show that the rate of association, rather than dissociation, is the main determinant of binding with the tested blood components,” said Asst Prof Drum. The multiplex SPR system was also used to study the effect of modification with polyethylene (PEG), a synthetic polymer commonly used in nanoparticle formulations to prevent protein accumulation. The researchers found that shorter PEG chains (2-10 kilodaltons) are about three to four times more effective than longer PEG chains (20-30 kilodaltons) at preventing corona formation. “The modular nature of our protocol allows us to study any nanoparticle which can be chemically tethered to the sensing surface,” explained Asst Prof Drum. “Using our technique, we can quickly evaluate a series of nanoparticle-based drug formulations before conducting in vivo studies, thereby resulting in savings in time and money and a reduction of in vivo testing,” he added. The researchers plan to use the technology to quantitatively study protein corona formation for a variety of nanoparticle formulations, and rationally design nanomedicines for applications in cardiovascular diseases and cancer. Here’s a link to and a citation for the paper, Component-Specific Analysis of Plasma Protein Corona Formation on Gold Nanoparticles Using Multiplexed Surface Plasmon Resonance by Abhijeet Patra, Tao Ding, Gokce Engudar, Yi Wang, Michal Marcin Dykas, Bo Liedberg, James Chen Yong Kah, Thirumalai Venkatesan, and Chester Lee Drum. Small DOI: 10.1002/smll.201501603 Article first published online: 10 SEP 2015 © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim This paper is behind a paywall. # Self-healing supercapacitors from Singapore Michael Berger has written up the latest and greatest regarding self-healing capacitors and carbon nanotubes (which could have more relevance to your life than you realize) in a March 10, 2014 Nanowerk Spotlight article, If you ever had problems with the (non-removable) battery in your iPhone or iPad then you well know that the energy storage or power source is a key component in a tightly integrated electronic device. Any damage to the power source will usually result in the breakdown of the entire device, generating at best inconvenience and cost and in the worst case a safety hazard and your latest contribution to the mountains of electronic waste. A solution to this problem might now be at hand thanks to researchers in Singapore who have successfully fabricated the first mechanically and electrically self-healing supercapacitor. Reporting their findings in Advanced Materials (“A Mechanically and Electrically Self-Healing Supercapacitor”) a team led by Xiaodong Chen, an associate professor in the School of Materials Science & Engineering at Nanyang Technological University, have designed and fabricated the first integrated, mechanically and electrically self-healing supercapacitor by spreading functionalized single-walled carbon nanotube (SWCNT) films on self-healing substrates. Inspired by the biological systems’ intrinsic self-repairing ability, a class of artificial ‘smart’ materials, called self-healing materials, which can repair internal or external damages have been developed over the past decade … Berger goes on to describe how the researchers addressed the issue of restoring electrical conductivity, as well as, restoring mechanical properties to self-healing materials meant to be used as supercapacitors. Here’s a link to and a citation for the team’s latest paper, A Mechanically and Electrically Self-Healing Supercapacitor by Hua Wang, Bowen Zhu, Wencao Jiang, Yun Yang, Wan Ru Leow, Hong Wang, & Xiaodong Chen. Advanced Materials Article first published online: 19 FEB 2014 DOI: 10.1002/adma.201305682 © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim Xiaodong Chen and his team were last mentioned here in a Jan. 9, 2014 posting in connection with their work on memristive nanodevices derived from protein. # Fish gets invisibility cloak first, cat waits patiently An invisibility cloak devised by researchers in Singapore and China is receiving a high degree of interest online with a June 14, 2013 news item on Nanowerk, a June 11, 2013 article by Philip Ball for Nature, and a June 13, 2013 article by Sarah Gates for Huffington Post. The research paper, Natural Light Cloaking for Aquatic and Terrestrial Creatures by Hongsheng Chen, Bin Zheng, Lian Shen, Huaping Wang, Xianmin Zhang, Nikolay Zheludev, Baile Zhang was submitted June 7, 2013 to arXiv.org (arXiv is an e-print service in the fields of physics, mathematics, computer science, quantitative biology, quantitative finance and statistics. Submissions to arXiv must conform to Cornell University academic standards. arXiv is owned and operated by Cornell University, a private not-for-profit educational institution), A cloak that can hide living creatures from sight is a common feature of mythology but still remains unrealized as a practical device. To preserve the phase of wave, the previous cloaking solution proposed by Pendry \emph{et al.} required transforming electromagnetic space around the hidden object in such a way that the rays bending around it have to travel much faster than those passing it by. The difficult phase preservation requirement is the main obstacle for building a broadband polarization insensitive cloak for large objects. Here, we suggest a simplifying version of Pendry’s cloak by abolishing the requirement for phase preservation as irrelevant for observation in incoherent natural light with human eyes that are phase and polarization insensitive. This allows the cloak design to be made in large scale using commonly available materials and we successfully report cloaking living creatures, a cat and a fish, in front of human eyes. What they seem to be saying is that it’s possible to create an invisibility cloak perceptible to the human eye that is made of everyday materials. I’ll show the fish video first. Pay attention as that fish darts behind its invisibility cloak almost as soon as the video starts (from the Nanowerk Youbube channel; June 14, 2013 Nanowerk news item), Then, there’s the cat (also from the Nanowerk Youtube channel), The June 11, 2013 article by Philip Ball for Nature describes the device which provides invisibility, … This latest addition to the science of invisibility cloaks is one of the simplest implementations so far, but there’s no denying its striking impact. The ‘box of invisibility’ has been designed by a team of researchers at Zhejiang University in Hangzhou, China, led by Hongsheng Chen, and their coworkers. The box is basically a set of prisms made from high-quality optical glass that bend light around any object in the enclosure around which the prisms are arrayed, the researchers describe in a paper posted on the online repository arXiv. Ball suggests that this latest invisibility cloak is very similar to a Victorian era music hall trick, As such, the trick is arguably closer to ‘disappearances’ staged in Victorian music hall using arrangements of slanted mirrors than to the modern use of substances called metamaterials to achieve invisibility by guiding light rays in unnatural ways. As far as I know, the ‘metamaterial’ invisibility cloaks require very sophisticated equipment for their production, are incredibly expensive, and aren’t all that practical. Gates’s June 13, 2013 article for the Huffington Post provides an overview of some of the recent work on invisibility cloaks and metamaterials, as well as, previous work done by Dr. Hongsheng Chen, an electromagnetics professor at Zhejiang University (China), and Baile Zhang, an assistant physics professor at Singapore’s Nanyang Technological University before they unveiled this latest invisibility cloak. My most recent posting on the topic was a June 6, 2013 piece on a temporal invisibility cloak. # Astonishing material, multi-use titanium dioxide nanofibres The enthusiasm in the Mar. 20, 2013 news release on EurekAlert about Darren Sun’s work with titanium dioxide nanofibres seems boundless, A new wonder material that can generate hydrogen, produce clean water and even create energy. Science fiction? Hardly, and there’s more – It can also desalinate water, be used as flexible water filtration membranes, help recover energy from desalination waste brine, be made into flexible solar cells and can also double the lifespan of lithium ion batteries. With its superior bacteria-killing capabilities, it can also be used to develop a new type of antibacterial bandage. Scientists at Nanyang Technological University (NTU) in Singapore, led by Associate Professor Darren Sun have succeeded in developing a single, revolutionary nanomaterial that can do all the above and at very low cost compared to existing technology. The Nanyang Technological University Mar. 20, 2013 news release (also posted to EurekAlert) gives details about how Sun created his ‘wonder’ material, This breakthrough which has taken Prof Sun five years to develop is dubbed the Multi-use Titanium Dioxide (TiO2). It is formed by turning titanium dioxide crystals into patented nanofibres, which can then be easily fabricated into patented flexible filter membranes which include a combination of carbon, copper, zinc or tin, depending on the specific end product needed. Titanium dioxide is a cheap and abundant material, which has been scientifically proven to have the ability to accelerate a chemical reaction (photocatalytic) and is also able to bond easily with water (hydrophilic). Prof Sun, 52, from NTU’s School of Civil and Environmental Engineering, said such a low-cost and easily produced nanomaterial is expected to have immense potential to help tackle ongoing global challenges in energy and environmental issues. With the world’s population expected to hit 8.3 billion by 2030, there will be a massive increase in the global demand for energy and food by 50 per cent and 30 per cent for drinking water (Population Institute report, titled 2030: The “Perfect Storm” Scenario). “While there is no single silver bullet to solving two of the world’s biggest challenges: cheap renewable energy and an abundant supply of clean water; our single multi-use membrane comes close, with its titanium dioxide nanoparticles being a key catalyst in discovering such solutions,” Prof Sun said. “With our unique nanomaterial, we hope to be able to help convert today’s waste into tomorrow’s resources, such as clean water and energy.” Prof Sun had initially used titanium dioxide with iron oxide to make anti-bacterial water filtration membranes to solve biofouling – bacterial growth which clogs up the pores of membranes, obstructing water flow. While developing the membrane, Prof Sun’s team also discovered that it could act as a photocatalyst, turning wastewater into hydrogen and oxygen under sunlight while still producing clean water. Such a water-splitting effect is usually caused by Platinum, a precious metal that is both expensive and rare. Here’s a list of what the researchers are claiming multi-use titanium dioxide materials can accomplish, from the news release, Producing hydrogen and clean water This discovery, which was published recently in the academic journal, Water Research, showed that a small amount of nanomaterial (0.5 grams of titanium dioxide nanofibres treated with copper oxide), can generate 1.53 millilitre of hydrogen in an hour when immersed in one litre of wastewater. This amount of hydrogen produced is three times more than when Platinum is used in the same situation. Depending on the type of wastewater, the amount of hydrogen generated can be as much as 200 millilitres in an hour. Also to increase hydrogen production, more nanomaterial can be used in larger amounts of wastewater. Producing low-cost flexible forward osmosis membranes Not only can titanium dioxide particles help split water, it can also make water filter membranes hydrophilic – allowing water to flow through it easily, while rejecting foreign contaminants, including those of salt, making it perfect for desalinating water using forward osmosis. Thus a new super high flux (flow rate) forward osmosis membrane is developed. This discovery was published recently in last month’s journal of Energy and Environmental Science. This is the first such report of TiO2 nanofibres and particles used in forward osmosis membrane system for clean water production and energy generation. Producing new antibacterial bandages With its anti-microbial properties and low cost, the membrane can also be used to make breathable anti-bacterial bandages, which would not only prevent infections and tackle infection at open wounds, but also promote healing by allowing oxygen to permeate through the plaster. The membrane’s material properties are also similar to polymers used to make plastic bandages currently sold on the market. Producing low-cost flexible solar cells Prof Sun’s research projects have shown out that when treated with other materials or made into another form such as crystals, titanium dioxide can have other uses, such as in solar cells. By making a black titanium dioxide polycrystalline sheet, Prof Sun’s team was able to make a flexible solar-cell which can generate electricity from the sun’s rays. Producing longer lasting lithium ion batteries Concurrently, Prof Sun has another team working on developing the black titanium dioxide nanomaterial to be used in Lithium ion batteries commonly used in electronic devices. Preliminary results from thin coin-like lithium ion batteries, have shown that when titanium dioxide sphere-like nanoparticles modified with carbon are used as the anode (negative pole), it can double the capacity of the battery. This gives such batteries a much longer lifespan before it is fully drained. The results were featured prominently in a highly respected Journal of Materials Chemistry on its cover page last year. As is expected these days, from the news release, Next step – commercialisation Prof Sun and his team of 20, which includes 6 undergraduates, 10 PhD students and 4 researchers, are now working to further develop the material while concurrently spinning off a start-up company to commercialise the product. They are also looking to collaborate with commercial partners to speed up the commercialisation process. Here’s a citation and a link for the paper, Novel-Structured Electrospun TiO2/CuO Composite Nanofibers for High Efficient Photocatalytic Cogeneration of Clean Water and Energy from Dye Wastewater by Siew Siang Lee, Hongwei Bai Zhaoyang Liu, & Darren Delai Sun. Water Research Available online 19 March 2013 In Press, Accepted Manuscript http://dx.doi.org/10.1016/j.watres.2012.12.044 This paper is behind a paywall. Good luck to Professor Sun and his colleagues. # The shrimp will save us Who knew that ceramics are a preferred material for body armour? Clearly, not me. According to the June 13, 2012 news item on Nanowerk, there’s a shrimp whose shell may offer inspiration for better quality ceramics used not only in military body armour but also in joint replacements. Here’s an image of one type of mantis shrimp, Flower Mantis Shrimp (Photo Credit Silke Baron) Pretty, isn’t it? Here’ s more from the June 13, 2012 news item on Nanowerk, A scientist from Nanyang Technological University (NTU) may be onto an ocean of discovery because of his research into a little sea creature called the mantis shrimp. The research is likely to lead to making ceramics – today’s preferred material for medical implants and military body armour – many times stronger. These findings were published in last Friday’s Science (“The Stomatopod Dactyl Club: A Formidable Damage-Tolerant Biological Hammer” [behind a paywall]), and focused on the mantis shrimp’s ability to shatter aquarium glass and crab shells alike. The common creature native to the Indo Pacific, has club-like ‘arms’ which can strike prey at speeds matching that of a 5.56mm rifle bullet. Each impact generates a force exceeding 50 kilograms, which is hundreds of times the mantis shrimp’s weight. The June 13, 2012 news release from Nanyang Technological University (Singapore) notes, Assistant Professor Ali Miserez, from NTU’s School of Materials Science Engineering (MSE) and School of Biological Sciences (SBS), collaborated with Dr James Weaver from Harvard University as well as scientists from the University of California-Riverside, Purdue University, and Brookhaven National Laboratory in the United States. They have observed down to the nanoscale the highly unique composite structure of the mantis shrimp’s club and discovered that it is weaved together in a unique fashion to create a structure tougher than many engineered ceramics. This is the first time that the mantis shrimp’s club is studied in such detail. “The highly damage resistant property of the mantis shrimp could be most useful in medical products such as hip and joint implants, as they sustain impacts hundreds of times daily during walking and daily activities,” said Asst Prof Miserez, a recipient of the National Research Foundation Fellowship, which provides a research grant of up to S$3 million over five years.

“Damaged hip implants are a real problem, and cost billions of dollars to the healthcare systems worldwide. They also cause painful surgeries to patients when they need to be replaced. Using a nature-inspired blueprint to design biocompatible implants is actually a ‘shrimple‘ solution.”

Thank you for that wordplay. ‘Shrimple’, indeed! More seriously, I have previously commented on hip replacements and the search for ways to improve them, most recently in my April 20, 2012 posting.

The June 13, 2012 news release from Nanyang Technological University goes on to discuss Dr. Miserez’s lab and other applications for the shrimp-inspired ceramic materials,

Designing a damage-resistant implant which is made out of a bio-compatible bone material would solve the above problems [bone loss, toxicity, and immune reactions], as the material exists naturally in the human body. Asst Prof Miserez, whose laboratory is situated at MSE’s Centre for Biomimetic Sensor Science, said they will continue their research to better understand the design and materials and will attempt to replicate it in the laboratory next year.

His team, which includes PhD student Shahrouz Amini, will be focusing on developing a new bio-compatible material which could be used for medical implants such as hip implants. However, the potential applications for these nature-inspired designs are widespread because the final product is expected to be lighter weight and more impact resistant than existing products. These could include new types of armour plating, lighter vehicles and tougher engine and aircraft components like pistons and gears, all of which suffer from impact, wear and abrasion damage over time. [emphasis mine]

Possible medical and military advances march hand in hand, again!

# More on quantum dots: a toxicity study; Merck action in Israel

I have two items on quantum dots today. The first concerns a toxicity study performed on primates at the University of Buffalo (NY, USA). From the May 22, 2012 news item by Will Soutter for Azonano,

A multi-institute toxicity study on quantum dots in primates has discovered that these nanocrystals are safe for a period of one year.

This finding is encouraging for researchers and physicians looking for novel techniques to treat diseases such as cancer using nanomedicine. The organizations involved in the study included the University at Buffalo, Nanyang Technological University, ChangChun University of Science and Technology, and the Chinese PLA General Hospital.

On digging a little further, I found this information on the University of Buffalo website, from their May 21, 2012 news release,

— Tiny luminescent crystals called quantum dots hold great promise as tools for treating and detecting diseases like cancer.

— A pioneering study to gauge the toxicity of quantum dots in primates has found cadmium-selenide quantum dots to be safe over intervals of time ranging from three months to a year. The study is likely the first to test the safety of quantum dots in primates.

— The authors say more research is needed to determine quantum dots’ long-term effect on health; elevated levels of cadmium from the quantum dots were found in the primates even after 90 days.

The research, which appeared on May 20 in Nature Nanotechnology online , is likely the first to test the safety of quantum dots in primates.

In the study, scientists found that four rhesus monkeys injected with cadmium-selenide quantum dots remained in normal health over 90 days. Blood and biochemical markers stayed in typical ranges, and major organs developed no abnormalities. The animals didn’t lose weight.

Two monkeys observed for an additional year also showed no signs of illness.

The first  results are hopeful but there are some concerns,

The new toxicity study — completed by the University at Buffalo, the Chinese PLA General Hospital, China’s ChangChun University of Science and Technology, and Singapore’s Nanyang Technological University — begins to address the concern of health professionals who worry that quantum dots may be dangerous to humans.

The authors caution, however, that more research is needed to determine the nanocrystals’ long-term effects in primates; most of the potentially toxic cadmium from the quantum dots stayed in the liver, spleen and kidneys of the animals studied over the 90-day period.

The cadmium build-up, in particular, is a serious concern that warrants further investigation, said Ken-Tye Yong, a Nanyang Technological University assistant professor who began working with Prasad [Paras N. Prasad] on the study as a postdoctoral researcher at UB.

A pilot study in non-human primates shows no adverse response to intravenous injection of quantum dots

Ling Ye, Ken-Tye Yong, Liwei Liu, Indrajit Roy, Rui Hu, Jing Zhu, Hongxing Cai, Wing-Cheung Law, Jianwei Liu, Kai Wang, Jing Liu, Yaqian Liu, Yazhuo Hu, Xihe Zhang, Mark T. Swihart, and Paras N. Prasad

Nature Nanotechnology (2012) doi:10.1038/nnano.2012.74

The acquisition of an Israeli quantum dot company by Merck is my second bit of quantum dot news, from the May 22, 2012 news item on Nanowerk,

Merck announced today that within the scope of a capital increase by the Israeli start-up company QLight Nanotech, it is acquiring an interest in the Jerusalem-based company. QLight Nanotech is a spin-off subsidiary of Yissum, the technology transfer company of the Hebrew University of Jerusalem. QLight Nanotech develops products for use in displays and energy-efficient light sources based on semiconductor nanoparticles known as quantum dots.

I understood that Merck was a pharmaceutical company so I was bit surprised to see this (from the May 22, 2012 news item on the Solid State Technology website)

“I am excited that our basic science discoveries on semiconductor nanocrystals are now being realized in innovative technological applications. The partnership with Merck, a world leader in materials for display applications, is a synergistic one allowing us at Qlight Nanotech to implement advanced chemicals manufacturing and applications’ know-how,” said the scientific founder of  QLight Nanotech, Professor Uri Banin of the Hebrew University of Jerusalem, who will continue to support the company as a shareholder and advisor alongside of Yissum.

In fact, Merck bills itself as a pharmaceuticals and a s chemicals company.

# Asia’s research effort in nano-, bio-, and information technology integrated in Asian Research Network

The Feb. 29, 2012 news item by Cameron Chai on Azonano spells it out,

An Asian Research Network (ARN) has been formed by the Hanyang University of Korea and RIKEN of Japan in collaboration with other institutes and universities in Asia. This network has been launched to reinforce a strong education and research collaboration throughout Asia.

The Asian Research Network website is here. You will need to use your scroll bars as it appears to be partially constructed (or maybe my system is so creaky that I just can’t see everything on the page). Towards the bottom (right side) of the home page,there are a couple of red buttons for PDFs of the ARN Pamphlet and Research Articles.

From page 2 of the ARN pamphlet, here’s a listing of the member organizations,

KOREA

Hanyang University
Samsung Electronics
Electronics and Telecommunication Research Institute
Seoul National University
Institute of Pasteur Korea
Korea Research Institute of Chemical Technology

JAPAN

RIKEN

INDIA

National Chemical Laboratory
Shivaji University
Indian Institutes of Science Education and Research
Pune University
Indian Institute of Technology-Madras (In Progress)
Indian Institute of Science (In Progress)

USA

University of Texas at Dallas
UCLA (In Progress)
f d i i ( )

CHINA

National Center for Nanoscience and Technology
Peking University

SINGAPORE

National University of Singapore
Nanyang Technological University (In Progress)
Stanford University In Progress)
University of Maryland (In Progress)

ISRAEL

Weizmann Institute of Science (In Progress)
Hebrew University Jerusalem

THAILAND

National Science and Technology Development Agency (In Progress)

I was a little surprised to see Israel on the list and on an even more insular note, why no Canada?

Getting back to the ARN, here are their aims, from page 2 of the ARN pamphlet,

We are committed to fostering talented human resources, creating a research network in which researchers in the region share their knowledge and experiences, and establishing a future-oriented partnership to globalize our research capabilities. To this end, we will achieve excellence in all aspects of education, research, and development in the area of fusion research between BT [biotechnology] and IT [information technology] based on NT [nanotechnology] in general. We will make a substantial contribution to the betterment of the global community as well as the Asian society.

I look forward to hearing more from them in the future.

# Nanosunscreens, zinc oxide, cancer, and the latest research

Researchers in Singapore (Nanyang Technological University and the National University of Singapore) have published a study suggesting that nano zinc oxide, found in some sunscreens, may potentially cause cancer. The Nov. 29, 2011 news item on Nanowerk provides this detail,

The chemical, Zinc Oxide, is used to absorb harmful ultra violet light. But when it is turned into nano-sized particles, they are able to enter human cells and may damage the cells’ DNA. This in turn activates a protein called p53, whose duty is to prevent damaged cells from multiplying and becoming cancerous. However, cells that lack p53 or do not produce enough functional p53 may instead develop into cancerous cells when they come into contact with Zinc Oxide nanoparticles. [emphases mine]

I was able to access the study and while I’m not an expert by any means I did note that the study was ‘in vitro’, in this case, the cells were on slides when they were being studied. It’s impossible to draw hard and fast conclusions about what will happen in a body (human or otherwise) since there are other systems at work which are not present on a slide.

A few items I was not able to determine (it’s in the study but I don’t understand the term ‘sonicate’ or others the researchers used),

• were the concentrations of nano zinc oxide used in the research the standard concentrations one would find in a sunscreen, and
• were the cells continuously exposed to nano zinc oxide, e.g. sitting in a bath of the chemical, or were the cells exposed in the way cells in a body would be exposed

I ask these questions not to so much to expose my ignorance but to point out how difficult it is draw conclusions from a study when you don’t have the training for it. In fact, if you read the news item on Nanowerk or the study (The role of the tumor suppressor p53 pathway in the cellular DNA damage response to zinc oxide nanoparticles [article behind paywall]), you’ll notice that even the researchers have phrased their findings very carefully.

You’ll also notice that there is another agenda (from the news item on Nanowerk),

The breakthrough also validated efforts by Asst Prof Loo and Asst Prof Ng to pioneer a research group in the emerging field of nanotoxicology, which is still very much in its infancy throughout the world.

The research team would also like to work with the European Union to uncover the risks involving nanomaterials and how these materials should be regulated before they are made commercially available. Asst Prof Joachim Loo, who received his Bachelor and Doctorate degrees from NTU, was the only Singaporean representative in a recent nanotechnology workshop held in Europe. At the workshop, it was agreed that research collaborations in nanotoxicology between EU and South-east Asia should be increased.

Another research study on nano zinc oxide was released last year (it was not cited in the references for the latest Nov. 2011 study). From the Aug. 20, 2010 news item on physorg.com,

A technique developed by Macquarie University has proven for the first time that a tiny amount of zinc from sunscreens is absorbed through the skin into the human body, but is not yet able to discern whether the zinc is in nanoparticle form.

Professor Brian Gulson of Macquarie University conducted the research – published online in the current edition of the journal Toxicological Sciences – with collaborators in CSIRO and the Australian National University and the Australian Photobiology Testing Facility. The research was widely reported on in February 2010 following a presentation by Gulson at a scientific conference.

The team traced the skin absorption of a highly purified and stable isotope which allowed them to distinguish the zinc from the sunscreen from that which is naturally present in the body or environment. Zinc is absolutely essential to bodily functions.

The researchers suggest that follow-up studies from the scientific community with different formulations over longer periods of time are essential, but that until evidence to the contrary is obtained, people spending time outdoors should continue to use sunscreens.

Getting back to that question about the concentration of the nano zinc oxide solution used in the most recent studies in Singapore, here’s what Brian Gulson had to say about nano zinc oxide concentrations in his work and about a shortcoming in his study (from an Australian Broadcasting Corporation [ABC] Feb. 25, 2010 interview with Ashley Hall,

BRIAN GULSON: I guess the critical thing was that we didn’t find large amounts of it getting through the skin. The sunscreens contain 18 to 20 per cent zinc oxide usually and ours was about 20 per zinc. So that’s an awful lot of zinc you’re putting on the skin but we found tiny amounts in the blood of that tracer that we used.

ASHLEY HALL: So is it a significant amount?

BRIAN GULSON: No, no it’s really not.

ASHLEY HALL: But Brian Gulson is warning people who use a lot of sunscreen over an extended period that they could be at risk of having elevated levels of zinc.

BRIAN GULSON: Maybe with young children where you’re applying it seven days a week, it could be an issue but I’m more than happy to continue applying it to my grandchildren.

ASHLEY HALL: This study doesn’t shed any light on the question of whether the nano-particles themselves played a part in the zinc absorption.

BRIAN GULSON: That was the most critical thing. This isotope technique cannot tell whether or not it’s a zinc oxide nano-particle that got through skin or whether it’s just zinc that was dissolved up in contact with the skin and then forms zinc ions or so-called soluble ions. So that’s one major deficiency of our study.

Of course, I have a question about Gulson’s conclusion  that very little of the nano zinc oxide was penetrating the skin based on blood and urine samples taken over the course of the study. Is it possible that after penetrating the skin it was stored in the cells  instead of being eliminated?

It seems it’s not yet time to press the panic button since more research is needed for scientists to refine their understanding of nano zinc oxide and possible health effects from its use.

Final note: The researchers listed on the Singapore study are: Kee Woei Ng, Stella P.K. Khoo, Boon Chin Heng, Magdiel I. Setyawati, Eng Chok Tan, Xinxin Zhao, Sijing Xiong, Wanru Fang, David T. Leong, and Joachim S.C. Loo