Articles from June 2013

Polymers Key To Oral Insulin

In a new study, a “bioadhesive” coating developed at Brown University significantly improved the intestinal absorption into the bloodstream of nanoparticles that someday could carry protein drugs such as insulin. Such a step is necessary for drugs taken by mouth, rather than injected directly into the blood. For protein-based drugs such as insulin to be taken orally rather than injected, bioengineers need to find a way to shuttle them safely through the stomach to the small intestine where they can be absorbed and distributed by the bloodstream. Researchers report an important technological advance: They show that a “bioadhesive” coating significantly increased the intestinal uptake of polymer nanoparticles in rats and that the nanoparticles were delivered to tissues around the body in a way that could potentially be controlled.
oral nanoparticle
“The results of these studies provide strong support for the use of bioadhesive polymers to enhance nano- and microparticle uptake from the small intestine for oral drug delivery,” wrote the researchers in the Journal of Controlled Release, led by corresponding author Edith Mathiowitz, professor of medical science at Brown University.

Extraordinary Sunlight Absorption With 1 nm-Thick Photovoltaics

Atom-thick photovoltaic sheets could pack hundreds of times more power per weight than conventional solar cells. A research team from Massuchusetts Institute of Technology (MIT) has found that an effective solar cell could be made from a stack of two one-molecule-thick materials: Most efforts at improving solar cells have focused on increasing the efficiency of their energy conversion, or on lowering the cost of manufacturing. But now MIT researchers are opening another avenue for improvement, aiming to produce the thinnest and most lightweight solar panels possible. Such panels, which have the potential to surpass any substance other than reactor-grade uranium in terms of energy produced per pound of material, could be made from stacked sheets of one-molecule-thick materials such as graphene or molybdenum disulfide.
Very thin Solar panelsGraphene (a one-atom-thick sheet of carbon atoms, shown at bottom in blue) and molybdenum disulfide (above, with molybdenum atoms shown in red and sulfur in yellow). The two sheets together are thousands of times thinner than conventional silicon solar cells.
Stacking a few layers could allow for higher efficiency, one that competes with other well-established solar cell technologies,” says Marco Bernardi, a postdoc in MIT’s Department of Materials Science who was the lead author of the paper. Maurizia Palummo, a senior researcher at the University of Rome visiting MIT through the MISTI Italy program, was also a co-author. Jeffrey Grossman, the Carl Richard Soderberg Associate Professor of Power Engineering at MIT, says the new approach “pushes towards the ultimate power conversion possible from a material” for solar power. Grossman is the senior author of a new paper describing this approach, published in the journal Nano Letters.

A Battery Made of Wood To Store Solar Energy

A research team supported by the University of Maryland and the U.S. National Science Foundation has invented a sliver of wood coated with tin that could make a tiny, long-lasting, efficient and environmentally friendly battery. But don’t try it at home yet – the components in the battery tested by scientists at the University of Maryland are a thousand times thinner than a piece of paper. Using sodium instead of lithium, as many rechargeable batteries do, makes the battery environmentally benign. Sodium doesn’t store energy as efficiently as lithium, so you won’t see this battery in your cell phone – instead, its low cost and common materials would make it ideal to store huge amounts of energy at once, such as solar energy at a power plant.
Existing batteries are often created on stiff bases, which are too brittle to withstand the swelling and shrinking that happens as electrons are stored in and used up from the battery. Liangbing Hu, Teng Li and their team found that wood fibers are supple enough to let their sodium-ion battery last more than 400 charging cycles, which puts it among the longest lasting nanobatteries.
sodium-ion battery
The inspiration behind the idea comes from the trees,” said Hu, an assistant professor of materials science. “Wood fibers that make up a tree once held mineral-rich water, and so are ideal for storing liquid electrolytes, making them not only the base but an active part of the battery.

Lead author Hongli Zhu and other team members noticed that after charging and discharging the battery hundreds of times, the wood ended up wrinkled but intact. Computer models showed that that the wrinkles effectively relax the stress in the battery during charging and recharging, so that the battery can survive many cycles.

Harpoons Catch Brain Cells Signals

Neuroscientists may soon be modern-day harpooners, snaring individual brain-cell signals instead of whales with tiny spears made of carbon nanotubes. Researchers from Duke University who invented the new device want to study signals from individual neurons and their interactions with other brain cells to better understand the computational complexity of the brain.
The new brain cell spear is a millimeter long, only a few nanometers wide and harnesses the superior electromechanical properties of carbon nanotubes to capture electrical signals from individual neurons.

brainharpoon1This image, taken with a scanning electron microscope, shows a new brain electrode that tapers to a point as thick as a single carbon nanotube

To our knowledge, this is the first time scientists have used carbon nanotubes to record signals from individual neurons, what we call intracellular recordings, in brain slices or intact brains of vertebrates,” said Bruce Donald, a professor of computer science and biochemistry at Duke University who helped developed the probe.


Toward The First Molecular Integrated Circuit

A molecular integrated circuit was created by a group of chemists and physicists from the Department of Chemistry Nano-Science Center at the University of Copenhagen – Denmark – and Chinese Academy of Sciences, Beijing. The breakthrough was made possible through an innovative use of the two dimensional carbon material graphene. Kasper Nørgaard is an associate professor in chemistry at the University of Copenhagen. He believes that the first advantage of the newly developed graphene chip will be to ease the testing of coming molecular electronic components. But he is also confident, that it represents a first step towards proper integrated molecular circuits.

molecular electronics

Graphene has some very interesting properties, which cannot be matched by any other material. What we have shown for the first time is that it’s possible to integrate a functional component on a graphene chip. I honestly feel this is front page news”, says Nørgaard.

The discovery “Ultrathin Reduced Graphene Oxide Films as Transparent Top-Contacts for Light Switchable Solid-State Molecular Junctions” has just been published online in the periodical Advanced Materials.

DNA Antennas Mimic Nature To Capture Solar Energy

Researchers at Chalmers University of Technology – Sweden – have found an effective solution for collecting sunlight for artificial photosynthesis. By combining self-assembling DNA molecules with simple dye molecules, the scientists have created a system that resembles nature‘s own antenna system. The Chalmers team are combining artificial photosynthesis with DNA nanotechnology. When constructing nano-objects that are billionths of a metre, DNA molecules have proven to function very well as building material. This is because DNA strands have the ability to attach to each other in a predictable manner. As long as the correct assembly instructions are given from the start, DNA strands in a test tube can bend around each other and basically form any structure.

Artificial PhotosynthesisAn artificial light-collecting antenna system. Binding a large number of light-absorbing molecules (“red balls”) to a DNA molecule, which is then modified with a porphyrin unit (blue) will result in the creation of a self-assembling system that resembles light harvesting in natural photosynthesis.

It’s like a puzzle where the pieces only fit together in one specific way,” says Bo Albinsson, professor of physical chemistry at Chalmers and head of the research team.. “That is why it is possible to draw a fairly complex structure on paper and then know basically what it will look like. We subsequently use those traits to control how light collection will take place“.

The results were recently published in the Journal of the American Chemical Society.

How To Save Earth From CO2 Pollution

Researchers from Ulsan National Institute of Science and Technology (UNIST), S. Korea, developed a novel, simple method to synthesize hierarchically nanoporous frameworks of nanocrystalline metal oxides such as magnesia and ceria by the thermal conversion of well-designed metal-organic frameworks (MOFs).

The novel material developed by UNIST research team has exceptionally high CO2 adsorption capacity which could pave the way to save the Earth from CO2 pollution.

Nanoporous materials consist of organic or inorganic frameworks with a regular, porous structure. Because of their uniform pore sizes they have the property of letting only certain substances pass through, while blocking others. Nanoporous metal oxide materials are ubiquitous in materials science because of their numerous potential applications in various areas, including adsorption, catalysis, energy conversion and storage, optoelectronics, and drug delivery. While synthetic strategies for the preparation of siliceous nanoporous materials are well-established, non-siliceous metal oxide-based nanoporous materials still present challenges.
UNIST team
“I believe MOF-driven strategy can be expanded to other nanoporous monometallic and multimetallic oxides with a multitude of potential applications, especially for energy-related materials” said Prof. Moon. “Because of its high CO2 adsorption capacity, it will open a new way for environmental solutions.

A description of the new research was published in the Journal of the American Chemical Society.


How To Print Tiny Batteries

3D printing can now be used to print lithium-ion microbatteries the size of a grain of sand. The printed microbatteries could supply electricity to tiny devices in fields from medicine to communications, including many that have lingered on lab benches for lack of a battery small enough to fit the device, yet provide enough stored energy to power them.

To make the microbatteries, a team based at Harvard University and the University of Illinois at Urbana-Champaign printed precisely interlaced stacks of tiny battery electrodes, each less than the width of a human hair.
3D printing battery
For the first time, a research team from the Wyss Institute at Harvard University and the University of Illinois at Urbana-Champaign demonstrated the ability to 3D-print a battery. This image shows the interlaced stack of electrodes that were printed layer by layer to create the working anode and cathode of a microbattery.
Not only did we demonstrate for the first time that we can 3D-print a battery, we demonstrated it in the most rigorous way,“said Jennifer Lewis, Ph.D., senior author of the study, who is also the Hansjörg Wyss Professor of Biologically Inspired Engineering at the Harvard School of Engineering and Applied Sciences (SEAS), and a Core Faculty Member of the Wyss Institute for Biologically Inspired Engineering at Harvard University. Lewis led the project in her prior position at the University of Illinois at Urbana-Champaign, in collaboration with co-author Shen Dillon, an Assistant Professor of Materials Science and Engineering there.
The results were published in today’s online edition of Advanced Materials.


Mounted On Smarphones, Sensors Diagnose Diabetes

Today’s technological innovation enables smartphone users to diagnose serious diseases such as diabetes or lung cancer quickly and effectively by simply breathing into a small gadget, a nanofiber breathing sensor, mounted on the phones.
Cell- Phones, Sensors Diagnose Diabetes

Il-Doo Kim, Associate Professor of Materials Science and Engineering Department at the Korea Advanced Institute of Science and Technology (KAIST) -Korea -, and his research team have recently published a cover paper entitled “Thin-Wall Assembled SnO2 Fibers Functionalized by Catalytic Pt Nanoparticles and their Superior Exhaled Breath-Sensing Properties for the Diagnosis of Diabetes,” in an academic journal, Advanced Functional Materials (May 20th issue), on the development of a highly sensitive exhaled breath sensor by using hierarchical SnO2 fibers that are assembled from wrinkled thin SnO2 nanotubes.


How to Produce Hydrogen From Water At Low Cost

Cheaper clean-energy technologies could be made possible thanks to a new discovery. Research team members led by Raymond Schaak, a professor of chemistry at Penn State, have found that an important chemical reaction that generates hydrogen from water is effectively triggered — or catalyzed — by a nanoparticle made of nickel and phosphorus, two inexpensive elements that are abundant on Earth. The results of the research will be published in the Journal of the American Chemical Society. Schaak explained that the purpose of this nanoparticle is to help produce hydrogen from water — a process that is important for many energy-production technologies including fuel cells and solar cells. “Water is an ideal fuel, because it is cheap and abundant, but we need to be able to extract hydrogen from it,” Schaak said. Hydrogen has a high energy density and is a great energy carrier, Schaak explained, but it requires energy to produce. To make its production practical, scientists have been hunting for a way to trigger the required chemical reactions with an inexpensive catalyst. Platinum works, but it is expensive and relatively rare, so Schaak and his team have been searching for alternative materials.

hydrogen-electric carThere were some predictions that nickel phosphide might be a good candidate, and we already had been working with nickel phosphide nanoparticles for several years,” Schaak said. “It turns out that nanoparticles of nickel phosphide are indeed active for producing hydrogen and are comparable to the best known alternatives to platinum.”


Nanotechnology-based Sensor Detects Skin Cancer

According to new research from the Monell Center – Philadelphia – and collaborating institutions, odors from human skin cells can be used to identify melanoma, the deadliest form of skin cancer. In addition to detecting a unique odor signature associated with melanoma cells, the researchers also demonstrated that a nanotechnology-based sensor could reliably differentiate melanoma cells from normal skin cells. The findings suggest that non-invasive odor analysis may be a valuable technique in the detection and early diagnosis of human melanoma.
Melanoma is a tumor affecting melanocytes, skin cells that produce the dark pigment that gives skin its color. The disease is responsible for approximately 75 percent of skin cancer deaths, with chances of survival directly related to how early the cancer is detected. Current detection methods most commonly rely on visual inspection of the skin, which is highly dependent on individual self-examination and clinical skill.
The current study took advantage of the fact that human skin produces numerous airborne chemical molecules known as volatile organic compounds, or VOCs, many of which are odorous.

There is a potential wealth of information waiting to be extracted from examination of VOCs associated with various diseases, including cancers, genetic disorders, and viral or bacterial infections,” notes George Preti, PhD, an organic chemist at Monell who is one of the paper’s senior authors.
In the study, published online ahead of print in the Journal of Chromatography B, researchers used sophisticated sampling and analytical techniques to identify VOCs from melanoma cells at three stages of the disease as well as from normal melanocytes.


Graphene Is The Solar Cells Future

Semiconductors grown on graphene at the Norwegian University of Science and Technology (NTNU) may be an important research breakthrough. At the centre of the research efforts are Professor Helge Weman, Professor Bjørn-Ove Fimland and post-doctoral fellow Dong-Chul Kim. The team is now working on translating the results of their basic research into an initial prototype. “Solar cell and LED technology will be the initial areas to see new products using semiconductors grown on graphene,” Dr Weman believes.

Under-priced fossil-fuel energy is the primary contributor to global warming. Sunlight is an alternative source with enormous potential, but solar energy will have to become less expensive and more efficient. Semiconductor nanowires based on graphene may just finally tip the scales in favour of solar energy.
graphene solar cells
If semiconductor nanowires grown on graphene are used in solar cells, the same amount of sunlight can be converted to energy using one-tenth the volume of materials used in thin-film solar cells. And that means we’ve cut down on even more material by growing the semiconductors on graphene instead of on a thick semiconductor substrate. New research also shows that graphene has additional unique properties that enhance the efficiency of a solar cell,” Dr Weman explains.“We are pioneers in that we are using graphene for something other than basic research. We may already have our first prototype in place by the end of 2013, but we don’t wish to reveal what it is yet,” Dr Weman says. “The field we are working with – using graphene as a replacement for silicon and other semiconductor substrates in electronics and solar cells – entails many new opportunities“.