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"Nanojuice" Could Diagnose Gastrointestinal Illnesses

Researchers at the University of Buffalo (UB) have developed what they're calling a "nanojuice", which when ingested enables doctors to see clear images of the small intestine in real time.

The novel medical imaging technique promises better diagnosis of a variety of gastrointestinal illnesses, including Crohn’s disease and celiac disease. Other medical imaging techniques used to examine the small intestine, such as X-rays, magnetic resonance imaging, and ultrasound, have drawbacks in terms of safety, accessibility to the organ, and an inability to produce clear images. 

Perhaps the biggest breakthrough of this technique is that unlike other imaging techniques it is capable of monitoring what’s happening in the small intestine in real time.

“Conventional imaging methods show the organ and blockages, but this method allows you to see how the small intestine operates in real time,” said Jonathan Lovell, assistant professor of biomedical engineering at UB in a press release. “Better imaging will improve our understanding of these diseases and allow doctors to more effectively care for people suffering from them.”

The key to the technique is the ingestion of a liquid with nanoparticles suspended in it, thus the name "nanojuice." The basis of the nanoparticles is a family of dyes known as napthalcyanines. While these molecules are great for absorbing light that make them ideal as a contrasting agent, alone they are unsuitable for use in the human body. First, they don’t disperse in a liquid; and, secondly, they could be absorbed in the intestine and transferred into the blood stream.

To counteract this, the UB researchers developed nanoparticles they dubbed “nanonaps” that contain the dye molecules inside them, imparting the ability to both disperse in liquid and pass through the intestine without problems.

In the research, which was published in the journal Nature Nanotechnology, the UB team gave the nanojuice to mice orally and then used photoacoustic tomography—a kind of ultrasound imaging that uses light-induced pressure waves. The result was that nanoparticles in the intestine could be visualized with low background and a high resolution.

This technique enables for the first time the visualization of peristalsis, which involves the contraction of muscles that moves food through the small intestine. The ability to observe this process in patients could not only help in the diagnosis of gastrointestinal illnesses but also help determine the link between peristalsis dysfunction and ranges of disorders, including diabetes and Parkinson’s disease.

The researchers plan to take this work to the next step, human trials, and test the technique in other areas of the gastrointestinal tract.

Start-up Puts the Carbon on the Cathode of Li-ion Batteries

The approach of many researchers seeking to improve the ubiquitous lithium-ion (Li-ion) battery has been to replace the graphite typically used for the battery's anode. Now, in work that originated at the University of Alberta in Canada, the focus has moved to the cathode. The result, claims lead researcher Xinwei Cui, is a battery that can deliver an energy output five to eight times that of the Li-ion batteries currently available.

So confident is Cui, whose research was published in the journal Nature Scientific Reports, that he has co-founded AdvEn Solutions, which is manufacturing the batteries for use in electronic devices and plans to have something on the market by the end of this year.

“What we’ve done is develop a new electrochemistry technology that can provide high energy density and high power density for the next generation,” said Cui in a press release.

The new electrochemistry involves using fluorinated carbon nanotubes in the cathode. Earlier attempts at using carbon and fluorine in the cathode had produced non-rechargeable batteries. Research instead focused on lithium-sulfur, or lithium-air based cathodes. But using flourinated carbon nanotubes allowed for a rechargeable battery that also overcomes some of the issues associated with the lithum-sulfur and lithium-air cathodes, such as large volume expansion when the cathode fills up with ions that shortens a battery's life span.

Batteries using the fluorinated carbon nanotubes in their cathode demonstrated a maximum discharging capacity of 2174 milliamp-hours per gram (mAh/g) and a specific energy density of 4113 Watt-hours per kilogram (Wh/kg), compared to  an average Li-ion battery that has a discharging capacity of 372mAh/g and a specific energy of around 100 to 265 Wh/kg.

AdvEn Solutions plans to produce three types of batteries based on fluorinated carbon nanotube architecture. One of the batteries will have a high power output and long-life cycle, the second will provide high energy and quick charging rates and the third will have a super-high energy storage capacity.

“We have a long way to go, but we’re on the right track. It’s exciting work and we want everyone to know about it and that it’s very young but promising,” said Cui.

Carbon Nanotubes Unzip Into Nanoribbons When Smashed

Researchers have "unzipped" carbon nanotubes into graphene nanoribbons using a variety of methods since the feat was demonstrated over five years ago.

But there has always been one unifying characteristic about those methods: they involved a chemical solution to get the tubes to transform into sheets. Now researchers at Rice University have discovered that if carbon nanotubes are shot at a target and hit it broadside, they unzip into the graphene nanoribbons.

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Three-Atom Thick Material Switches Between a Conductor and an Insulator When Tugged

As chip dimensions have decreased to match the demands of Moore’s Law, insulating materials separating the transistor gate from the channel below it have had to be thinned down so much that keeping current from leaking through has been difficult. In fact, chipmakers are no longer thinning the gate oxide, and it stands now at 1 nanometer in thickness because to go thinner would allow too much current to flow through the channel when the transistor is supposed to be turned off.

Researchers at Stanford University have been running simulations with some two-dimensional materials that when sandwiched together can switch the material between conducting and insulating just by tugging on its edges.  If physical experiments on the material are successful, it could provide a way to completely shut down the leakage of current in chips and still go to smaller chip dimensions.

The researchers believe that if the material could be used in today's smart phone processors it could reduce their power consumption considerably.

The work, which was published in the journal Nature Communications, represents a growing body of knowledge on so-called transition dichalcogenide metals, which are materials that combine one of 15 transition metals with one of three members of the chalcogen family: sulfur, selenium, or tellurium.

In the computer models, the Stanford researchers took one atomic layer of molybdenum atoms and sandwiched it between two atomic layers of tellurium atoms. In the video below, you can see the three-atom thick structure switch between conductor and an insulator as it us pulled.

It does make an attractive computer model. However, whether it can be translated into an actual physical material remains to be seen. Even if they can produce the three-atom-thick sandwich, it’s not clear whether it could really be developed for large-scale production. While physical experiments have successfully demonstrated single-atom transistors, many are questioning whether such a device could ever be be made by the millions or billions.

It’s not clear that a now three-year-old challenge of Professor Mike Kelly at Cambridge University has ever been sufficiently answered. In the challenge he argues that devices with dimensions less than three nanometers cannot be mass produced using a top-down manufacturing technique. Until that question is adequately addressed, we may have here just another computer model that could lead to a physical material but not one that could be used in the mass production of electronic devices.

US Government Regulators Take on Nanomaterials

Besides a big funding gap that has prevented many nascent nanotechnologies from reaching the marketplace, two major obstacles to nanotech's advance are a seeming lack of a regulatory framework, especially in food and drugs, and environmental, health and safety (EHS) concerns.

This week, in what appears to be a coincidence, the US Food & Drug Administration (FDA) and the National Nanotechnology Initiative (NNI) have both issued formal announcements that should have an impact on both regulations and EHS concerns. The FDA has outlined a policy for overseeing nanomaterials in food, drugs and even cosmetics. Yesterday, the NNI provided an overview of progress on the implementation of the 2011 NNI Environmental, Health and Safety (EHS) Research Strategy.

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Kickstarter Comes to Nanomaterials

The IEEE Spectrum Facebook page received an exuberant, almost breathless, urging last week for the online magazine to promote a company called Aken Technologies. The firm is developing a hydrophobic nanomaterial that is designed to keep textiles from getting wet or stained.

If there is one thing that is not novel in the developing world of nanomaterials, it is stain-resistant textiles. As far back as 1998, David Soane founded Nanotex as a company that produced stain-resistant textiles. In the ensuing 16 years, the company has exhibited resilience and success, despite increasing competition, most notably from Swiss-based Schoeller Technologies. We even covered, in the pages of this blog, how the Italian cycling apparel company, Castelli, sourced Schoeller’s Nano Sphere technology to develop water repellant cycling wear.

Textiles haven't been the lone application for hydrophobic nanomaterials. The materials have also proven themselves effective for our beloved smart phones. Soon after they were developed in the labs, hydrophobic nanocoatings for smart phones were already the rage at the Consumer Electronics Show back in 2012.

So, while there may be nothing new about hydrophobic nanomaterials, there was something novel about Aken Technologies beyond its claim to be the “first in the industry” to be “100% Safe, Non-Toxic, Green, & Eco-Friendly.” The novel bit—at least to me—was that it was relying on Kickstarter, the crowdfunding site, for its initial funding.

I soon found out, however, that Aken was not the first nanotechnology-related company to use Kickstarter for its funding mechanism, or even the first company trying to fund a hydrophobic nanomaterial for textiles. A project dubbed Silic used Kickstarter late last year to fund a hydrophobic nanomaterial. Silic initially aimed to raise US $20,000, but quickly overshot its goal, securing $112,254 in funding. At least now, Silic has a website, a milestone that Aken Technologies has yet to achieve.

The funding gap remains one of the biggest obstacles for bringing nanotechnologies developed in the lab to the market place. Whether Kickstarter can become a viable method for bridging that gap remains to be seen. However, it’s hard to see how funding a few small companies so that they can develop the commercial potential for a technology that has already been in commercial markets for nearly two decades recommends it as the solution.

There’s nothing to clearly indicate that Kickstarter is offering an avenue for the unscrupulous to relieve people of their money. Unfortunately, we apparently have seen with other “nanotech investment opportunities” the potential for abuse, which has led the UK Financial Conduct Authority (FCA) to warn investors to beware of scams involving graphene.

The skepticism of the Kickstarter investors is not encouraging, if the questions that are posted on Aken Technologies’ Kickstarter page are any indication. The “investors” don’t really seem to be formulating the right questions. (Their questions are reasonable but not relevant to Aken's prospects for success.) A typical question is something along the lines of: "Will this technology work?" Yes, it works; there’s been a long commercial history of hydrophobic materials being used effectively in textiles. Instead, what potential investors should be asking is how Aken's offering is better than—or how can it even compete with—long-established companies that do the same.

After the excitement of seeing water bouncing off a t-shirt wears off, an understanding of the startup's market position needs to be soaked up.

Nanowires for Tougher Touchscreens

Many of us have experienced that sinking feeling after dropping an expensive smart phone on the asphalt and realizing that the screen is shattered.

That heartbreak may be a thing of the past due to research out of the University of Akron: a new transparent electrode material that makes the screen virtually shatterproof.

There has been a huge push in nanomaterial research with the aim of finding a replacement for indium tin oxide (ITO), which is the material from which transparent conductors that control screen pixels are made.

One of the problems with ITO is that it’s a relatively scarce resource, and with the market for tablets and smart phones exploding, that scarcity has become more acute. This market shortage, combined with the brittleness of ITO-based screens, explains why a variety of nanomaterials have been given a “market pull” opportunity rather than merely a “technology push” prayer.

“These two pronounced factors drive the need to substitute ITO with a cost-effective and flexible conductive transparent film,” said Yu Zhu, an assistant professor at the University of Akron, in a press release. “We expect this film to emerge on the market as a true ITO competitor. The annoying problem of cracked smartphone screens may be solved once and for all with this flexible touchscreen.”

Xu and his colleagues published their results in the journal ACS Nano; the paper describes the process they used to create their transparent film.

They started with conductive metal films (copper, in this case) on which they patterned transparent metal nanowire networks with electrospun fibers as a mask. Then, with the metal nanowires, they fabricated transparent electrodes on both rigid glass and polymer (polyethylene terephthalate (PET)) substrates.

The researchers claim that both the transmittance (the amount of light that passes through a material) and the sheet resistance (a measurement of a thin film's resistance to electrical current) of the metal nanowire-based electrodes they have developed are better than ITO-based electrodes.

Two years ago, Samsung made a transparent conductor from graphene, and there are a number of companies already out there—like Cambrios, and Blue Nano, to name a couple—that are marketing silver-nanowire-based transparent electrodes. If this copper-nanowire-based transparent electrode solution is going to be the next ITO, it’s got a lot of competitors fighting for the same role.

Li-ion Batteries with Nanotube Anodes Charge Phones in Ten Minutes

The introduction of portable electronics pretty much spelled the end for graphite as the anode material for lithium-ion (Li-ion) batteries. We could no longer get through a day of regular usage of some smart phones without having to recharge their batteries.

The hope had been that silicon could replace graphite. Silicon anode material has a theoretical capacity (i.e., Li storage capability) of 4000 milliamp-hours per gram (mAh/g). This represented an enormous increase over graphite that was coming in at 372mAh/g. However, there was a big problem: silicon would start to crack after a relatively small number of charge/discharge cycles, rendering the material useless.

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Nanoparticle Self Assembly of Wafer-Scale Thin Films Done in Minutes

Researchers at the U.S. Department of Energy (DOE)’s Lawrence Berkeley National Laboratory (Berkeley Lab) have developed a technique the rapidly builds wafer-scale thin films through nanoparticle self-assembly.

Prior to this work, it would take hours for nanoparticles to self assemble into a film that was just barely able to cover a microscopic chip. Now a film covering a full-sized silicon wafer can assemble itself in just a few minutes.

Because this new technique should be compatible with today's manufacturing processes, the Berkeley Lab researchers believe that it could lead to new types of optical coatings for applications in photovoltaics and data storage.

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Nanowires Enable a Cable To Both Conduct and Store Electricity

Jayan Thomas, an assistant professor at the University of Central Florida’s NanoScience Technology Center, thought it would be interesting to see if the copper cable we use to conduct electricity could also be used to store energy. So he and his graduate student, Zenan Yu, set out to see if they could make it so.

Thomas and his team had previously been working on inexpensive nanoprinting techniques for producing supercapacitors with highly ordered nanoelectrodes. When they looked for a solution to both conducting and storing electricity in a single cable they again turned to supercapacitors.

In this latest research, which will be reported in the 30 June edition of Advanced Materials, Thomas and Yu essentially wrapped a supercapacitor around a copper cable. The problem they had to overcome was how to create the two electrodes necessary for a supercapacitor.

The trick was to grow electrochemically active nanowires (or nanowhiskers) on a copper wire that had been coated with copper oxide. This layer of nanowires sticking out from the cable created the first electrode for the supercapacitor. The researchers then covered the copper cable and nanowhiskers with a polymer. Next they surrounded the polymer with a nanowire coated copper coil, forming the second electrode.

The insulation of the separator allows the inner copper wire to continue conducting electricity while the layers around the wire can independently store the energy.

In an article published in the journal Nature discussing the work, it is pointed out that design is limited to direct current (DC), which could prove useful for powering small electronic devices and automotive electronics, but not for household or industrial uses that need alternating current (AC).

While this is still pretty preliminary research, Thomas believes that the technology could be transferred to other types of materials such as fibers that could be woven into clothing to power electronic devices. Others believe that the supercapacitor cables might be effective for storing the electrical energy produced by solar panels or wind turbines. In any case, the manufacturing costs of the cables will need to be kept low if they are realistically going to be able to offer an alternative to today's supercapacitor devices.

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Nanoclast

IEEE Spectrum’s nanotechnology blog, featuring news and analysis about the development, applications, and future of science and technology at the nanoscale.

 
Editor
Dexter Johnson
Madrid, Spain
 
Contributor
Rachel Courtland
Associate Editor, IEEE Spectrum
New York, NY
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