Articles from November 2012

DNA Nanobricks like a LEGO Game

Researchers at the Wyss Institute for Biologically Inspired Engineering at Harvard University have created more than 100 three-dimensional (3D) nanostructures using DNA building blocks that function like Lego® bricks — a major advance from the two-dimensional (2D) structures the same team built a few months ago. In effect, the advance means researchers just went from being able to build a flat wall of Legos®, to building a house. The new method, featured as a cover research article in the 30 November issue of Science, is the next step toward using DNA nanotechnologies for more sophisticated applications than ever possible before, such as “smart” medical devices that target drugs selectively to disease sites, programmable imaging probes, templates for precisely arranging inorganic materials in the manufacturing of next generation computer circuits, and more.

Wyss Institute researchers have created more than 100 three-dimensional nanostructures using DNA building blocks that function like Lego® bricks. This video illustrates how DNA is used to build these structures. Watch video…

The DNA-brick technique capitalizes on the ability of DNA strands to selectively attach to other strands, thanks to the underlying “recipe” of DNA base pairs. This animation shows how the DNA strands self-assemble to build a structure. View animation…


How To Help Planes Fly Safely Trough Icy Condidions?

To help planes fly safely through cold, wet, and icy conditions, a team of Japanese scientists has developed a new super water-repellent surface that can prevent ice from forming in these harsh atmospheric conditions. Unlike current inflight anti-icing techniques, the researchers envision applying this new anti-icing method to an entire aircraft like a coat of paint.
As airplanes fly through clouds of super-cooled water droplets, areas around the nose, the leading edges of the wings, and the engine cones experience low airflow, says Hirotaka Sakaue, a researcher in the fluid dynamics group at the Japan Aerospace Exploration Agency (JAXA). This enables water droplets to contact the aircraft and form an icy layer. If ice builds up on the wings it can change the way air flows over them, hindering control and potentially making the airplane stall. Other members of the research team are with the University of Tokyo, the Kanagawa Institute of Technology, and Chuo University.

Current anti-icing techniques include diverting hot air from the engines to the wings, preventing ice from forming in the first place, and inflatable membranes known as pneumatic boots, which crack ice off the leading edge of an aircraft’s wings. The super-hydrophobic, or water repelling, coating being developed by Sakaue, Katsuaki Morita – a graduate student at the University of Tokyo – and their colleagues works differently, by preventing the water from sticking to the airplane’s surface in the first place.

Music Can Help Fine-Tune Silk Fiber Properties.

Pound for pound, spider silk is one of the strongest materials known: Research by MIT’s Markus Buehler has helped explain that this strength arises from silk’s unusual hierarchical arrangement of protein building blocks. Now Buehler — together with David Kaplan of Tufts University and Joyce Wong of Boston University — has synthesized new variants on silk’s natural structure, and found a method for making further improvements in the synthetic material. And an ear for music, it turns out, might be a key to making those structural improvements.

This diagram of the molecular structure of one of the artificially produced versions of spider silk depicts one that turned out to form strong, well-linked fibers. A different structure, made using a variation of the same methods, was not able to form into the long fibers needed to make it useful. Musical compositions based on the two structures helped to show how they differed.

“We’re trying to approach making materials in a different way,” Buehler explains, “starting from the building blocks” — in this case, the protein molecules that form the structure of silk. “It’s very hard to do this; proteins are very complex”.

Flexible Electronics 22 Times Faster

A team of researchers from the University of Pennsylvania has shown that nanoscale particles, or nanocrystals, of the semiconductor cadmium selenide can be “printed” or “coated” on flexible plastics to form high-performance electronics. Electronic circuits are typically integrated in rigid silicon wafers, but flexibility opens up a wide range of applications. In a world where electronics are becoming more pervasive, flexibility is a highly desirable trait, but finding materials with the right mix of performance and manufacturing cost remains a challenge.

Professor Cherie Kagan, from the School of Arts and Sciences explains: ’“We have a performance benchmark in amorphous silicon, which is the material that runs the display in your laptop, among other devices,” Kagan said. “Here, we show that these cadmium selenide nanocrystal devices can move electrons 22 times faster than in amorphous silicon.
The research was led by David Kim, a doctoral student in the Department of Materials Science and Engineering in Penn’s School of Engineering and Applied Science; Yuming Lai, a doctoral student in the Engineering School’s Department of Electrical and Systems Engineering; and Professor Cherie Kagan, who has appointments in both departments as well as in the School of Arts and Sciences’ . Benjamin Diroll, a doctoral student in chemistry, and Penn Integrates Knowledge Professor Christopher Murray of Materials Science and of Chemistry also collaborated on the research. The work was published in the journal Nature Communications.

Nanoparticle Kills Prostate Cancer, Not Healthy Tissues

A team led by John Lewis, the Sojonky Chair in Prostate Cancer Research with the Canadian University of Alberta’s Faculty of Medicine & Dentistry, and PhD student Choi Fong Cho, have authored a report about a new platform to generate nano-particles to seek out and destroy only cancer cells. “Chemotherapy … is indiscriminate,” said Lewis. “So it kills any cell that’s dividing in the body, and cancer cells are dividing but so are hair cells and immune cells – and that’s what causes the majority of side effects. So this platform will allow us then to take chemotherapies and avoid those healthy tissues that we need, and specifically kill the cancer cells.” Most of the lab testing, involving animal models, has been for prostate cancer but Lewis noted that the drugs look for a protein only in cancer cells, acting like a “homing beacon” for many different kinds of cancer.

If we can use ‘smart‘ drugs that home in on tumours, we can dramatically decrease side effects for patients, lower the chance of recurrence, and hopefully increase the cancer survival rate.”


New Polymer Nanoparticles Kill 95 % of Cancer Cells

Researchers at Wake Forest Baptist Medical Center have modified electrically-conductive polymers, commonly used in solar energy applications, to develop revolutionary polymer nanoparticles (PNs) for a medical application. When the nanoparticles are exposed to infrared light, they generate heat that can be used to kill colorectal cancer cells.

Levi-Polyachenko and her team discovered a novel formulation that gives the polymers two important capabilities for medical applications: the polymers can be made into nanoparticles that are easily dispersed in water and generate a lot of heat when exposed to infrared light.Results of this study showed that when colorectal cancer cells incubated with the PNs were exposed to five minutes of infrared light, the treatment killed up to 95 percent of cells. “The results of this study demonstrate how new medical advancements are being developed from materials science research,” said Levi-Polyachenko.
The study was directed by Assistant Professor of Plastic and Reconstructive Surgery, Nicole H. Levi-Polyachenko, Ph.D., and done in collaboration with colleagues at the Center for Nanotechnology and Molecular Materials at Wake Forest University. This study was recently published online, ahead of print, in the journal, Macromolecular Bioscience (DOI: 10.1002/mabi.201200241)

5 Times More Efficient Against a Childhood Cancer

In a world-first, researchers from the Australian Centre for Nanomedicine at the University of New South Wales (UNSW) in Sydney – Australia – have developed a nanoparticle that could improve the effectiveness of chemotherapy for neuroblastoma by a factor of five. Neuroblastoma is an aggressive childhood cancer that often leaves survivors with lingering health problems due to the high doses of chemotherapy drugs required for treatment. Anything that can potentially reduce these doses is considered an important development. The UNSW researchers developed a non-toxic nanoparticle that can deliver and release nitric oxide (NO) to specific cancer cells in the body. The findings of their in vitro experiments have been published in the journal Chemical Communications.

When we injected the chemo drug into the neuroblastoma cells that had been pre-treated with our new nitric oxide nanoparticle we needed only one-fifth the dose,” says co-author Dr Cyrille Boyer from the School of Chemical Engineering at UNSW.
By increasing the effectiveness of these chemotherapy drugs by a factor of five, we could significantly decrease the detrimental side-effects to healthy cells and surrounding tissue.


Super-efficient Solar Energy Technology

Rice University scientists have unveiled a revolutionary new technology that uses nanoparticles to convert solar energy directly into steam. The new “solar steam” method from Rice’s Laboratory for Nanophotonics (LANP) is so effective it can even produce steam from icy cold water. The technology has an overall energy efficiency of 24 percent. Photovoltaic solar panels, by comparison, typically have an overall energy efficiency around 15 percent. However, the inventors of solar steam said they expect the first uses of the new technology will not be for electricity generation but rather for sanitation and water purification in developing countries.

Rice University graduate student Oara Neumann, left, and scientist Naomi Halas are co-authors of new research on a highly efficient method of turning sunlight into heat. They expect their technology to have an initial impact as an ultra-small-scale system to treat human waste in developing nations without sewer systems or electricity.
“This is about a lot more than electricity,” said LANP Director Naomi Halas, the lead scientist on the project. “With this technology, we are beginning to think about solar thermal power in a completely different way.”

Immune Diseases Beated By Biodegradable Nanoparticule

A biodegradable nanoparticle, designed by a Northwestern University medicine research team, turns out to be the perfect vehicle to stealthily deliver an antigen that tricks the immune system into stopping its attack on myelin and halt a model of relapsing remitting multiple sclerosis (MS) in mice. This is a breakthrough for nanotechnology and multiple sclerosis. The new nanotechnology also can be applied to a variety of immune-mediated diseases including Type 1 diabetes, food allergies and airway allergies such as asthma.

This is a highly significant breakthrough in translational immunotherapy,” said Stephen Miller, a corresponding author of the study and the Judy Gugenheim Research Professor of Microbiology-Immunology at Northwestern University Feinberg School of Medicine. “The beauty of this new technology is it can be used in many immune-related diseases. We simply change the antigen that’s delivered.
The holy grail is to develop a therapy that is specific to the pathological immune response, in this case the body attacking myelin,” Miller added. “Our approach resets the immune system so it no longer attacks myelin but leaves the function of the normal immune system intact.“

Nanotechnologies Help To Heal Nuclear Damages

Researchers at the California Institute of Technology (Caltech) have brought new understanding to one of those secrets — how the interfaces between two carefully selected metals can absorb, or heal, radiation damage. Some nano-engineered materials are able to resist such damage and may, for example, prevent helium bubbles from coalescing into larger voids. For instance, some metallic nanolaminates—materials made up of extremely thin alternating layers of different metals—are able to absorb various types of radiation-induced defects at the interfaces between the layers because of the mismatch that exists between their crystal structures.

When it comes to selecting proper structural materials for advanced nuclear reactors, it is crucial that we understand radiation damage and its effects on materials properties. And we need to study these effects on isolated small-scale features,” says Julia R. Greer, an assistant professor of materials science and mechanics at Caltech. With that in mind, Greer and colleagues from Caltech, Sandia National Laboratories, UC Berkeley, and Los Alamos National Laboratory have taken a closer look at radiation-induced damage, zooming in all the way to the nanoscale — where lengths are measured in billionths of meters.
Their results appear online in the journals Advanced Functional Materials and Small.


Gene Delivery Vehicle Goes To The Heart Of The Target.

Many types of tumor form a compact mass, like the phalanx formation of Greek antiquity. And although many drugs are known to be toxic to cancer cells, they are often unable to percolate into the inner recesses of the tumor. Upon intravenous administration, for instance, cytotoxic drugs may only be able to penetrate the outermost layers of a solid tumor. A team led by Ludwig Maximilians Universitat Munchen LMU-Germany – pharmacologist Dr Manfred Ogris has now developed a new type of gene delivery vehicle, which is designed to open up a route through the vascular network that supplies the tumor so that drugs can reach their target. A new strategy employing gene therapy could provide a solution to this problem. The idea is to deliver the gene for TNFα directly and specifically to the tumor cells. If this worked, the tumor cells themselves could produce and secrete the cytokine, ensuring that its local concentration becomes sufficiently high to permeabilize the blood vessels only in the immediate vicinity of the tumor.

We first designed a version of the TNFα gene that allows for the production of large amounts of the protein,” Dr. Baowei Su, first author on the study, explains.

Ultrathin Films Achieve High Solar Energy Efficiency

Using the power of the sun and ultrathin films of iron oxide (commonly known as rust), Technion-Israel Institute of Technology researchers have found a novel way to split water molecules to hydrogen and oxygen. The breakthrough, published this week in Nature Materials, could lead to less expensive, more efficient ways to store solar energy in the form of hydrogen-based fuels. This could be a major step forward in the development of viable replacements for fossil fuels.

“Our approach is the first of its kind,” says lead researcher Associate Prof. Avner Rothschild, of the Department of Materials Science and Engineering at Technion-Israel Institute of Technology. “We have found a way to trap light in ultrathin films of iron oxide that are 5,000 thinner than an office paper. This enables achieving high solar energy conversion efficiency and low materials and production costs.
Let’s remind that two days ago Swiss Scientists from Ecole Polytechnique Fédérale de Lausanne (EPFL) – Switzerland – have declared that they are producing hydrogen from sunlight, water and rust. Their prototypes shared the same basic principle: a dye-sensitized solar cell – invented by Michael Grätzel, a colleague from University of Geneva, – combined with an oxide-based semiconductor. The device is completely self-contained. More on