Tuesday, November 30, 2010

Center for Integrated Nanotechnologies

Center for Integrated Nanotechnologies

The Center for Integrated Nanotechnologies (CINT) is a Department of Energy/Office of Science user facility devoted to establishing the scientific principles that govern the design, performance, and integration of nanoscale materials. It is located in Albuquerque, N.M. Photo by Randy Montoya.

Photo license: All Rights Reserved By SandiaLabs This photo was taken on November 16, 2010 in Albuquerque, New Mexico, US, using a Nikon D700.

AFM positioning: Shining light on a needle in a haystack

The researchers characterize their new technique as a neat solution to the "needle in a haystack" problem of nanoscale microscopy, but it's more like the difference between finding the coffee table in a darkened room either by walking around until you fall over it, or using a flashlight. In a new paper,* a group from JILA—a joint venture of the National Institute of Standards and Technology (NIST) and the University of Colorado—finds tiny assemblies of biomolecules for subsequent detailed imaging by combining precision laser optics with atomic force microscopy.

The atomic force microscope (AFM) has become one of the standard tools of nanotechnology. The concept is deceptively simple. A needle—not unlike an old-fashioned phonograph stylus, but much smaller with a tip at most only a couple of atoms wide—moves across the surface of the specimen. A laser measures tiny deflections of the tip as it is pushed or pulled by atomic scale forces, such as electrostatic forces or chemical attraction. Scanning the tip back and forth across the sample yields a three-dimensional image of the surface. The resolution can be astonishing—in some cases showing individual atoms, a resolution a thousand times smaller than the best optical microscopes can achieve.

Atomic Force Microscopy Laser Targeting

Caption: "Laser targeting" for nanoscale microscopy: On the left, a typical 900 square micrometer view, using focused laser beam, shows potentially interesting purple membrane patch, which is marked with the square. Right top, closer optical image of patch; bottom, same target imaged with AFM revealing topological detail.

Credit: A.B. Churnside, University of Colorado at Boulder. Usage Restrictions: None.
Such amazing sensitivity incurs a technical problem: if your probe can image an object of, say, 100 square nanometers, how exactly do you find that object if it could be nearly anywhere on a microscope stage a million times that size? That's not an unusual case in biological applications. The brute-force answer is, you scan the probe back and forth, probably at a higher speed, until it runs into something interesting. Like the coffee table in the dark, this has problems. The AFM tip is not only very delicate and easy to damage, but it can be degraded by picking up unwanted atoms or molecules from the surface.
Also, in the biosciences, where the AFM is becoming increasingly important, research specimens usually are "soft" things like proteins or membranes that can be damaged by an uncontrolled collision with the tip. One solution has been to "label" the target molecule with a small fluorescent compound or quantum dot, so that it lights up and is easy to find, but that means chemically altering the subject, which may not be desirable.

Instead, the JILA team opted to use a flashlight. Building upon an earlier innovation for stabilizing the position of an AFM tip, the group uses a tightly focused, low-power laser beam to optically scan the area, identifying target locations by minute changes in the scattered light. This laser is scanned across the sample to form an image, analogous to forming an AFM image.

The same laser—and detection technique—is used to locate the AFM tip. Hence, the laser serves as a common frame of reference and it's relatively straightforward to align the optical and the AFM image. In experiments with patches of cell membrane from single-cell organisms,** the group has demonstrated that they can locate these protein complexes and align the AFM tip with a precision of about 40 nanometers. Relying solely on scattered light, their technique requires no prior chemical labeling or modification of the target molecules.

"You solve a couple of problems," says NIST physicist Thomas Perkins. "You solve the problem of finding the object you want to study, which is sort of a needle in a haystack problem. You solve the problem of not contaminating your tip. And, you solve the problem of not crashing your tip into what you were looking for. This prevents damaging your tip and, for soft biological targets, not damaging your sample." And, he says, it's much more efficient. "From a practical perspective, instead of my grad student starting to do real science at 4 p.m., she can start doing science at 10 a.m." ###

* A.B. Churnside, G.M. King and T.T. Perkins. Label-free optical imaging of membrane patches for atomic force microscopy. Optics Express. Vol. 18, No. 23. Nov. 8, 2010.

** The team used "purple membrane," which is cell membrane from certain single-cell organisms and contains bacteriorhodopsin, a protein that captures light energy. Bacteriorhodopsin is embedded in purple membrane and is a common protein for research in the biosciences.

Contact: Michael Baum michael.baum@nist.gov 301-975-2763 National Institute of Standards and Technology (NIST)

Monday, November 29, 2010

New Highly Stable Fuel-Cell Catalyst Gets Strength from its Nano Core

Palladium core protects precious platinum; enhances reactivity/stability.

UPTON, NY - Stop-and-go driving can wear on your nerves, but it really does a number on the precious platinum that drives reactions in automotive fuel cells. Before large fleets of fuel-cell-powered vehicles can hit the road, scientists will have to find a way to protect the platinum, the most expensive component of fuel-cell technology, and to reduce the amount needed to make catalytically active electrodes.

Now, scientists at the U.S. Department of Energy's (DOE) Brookhaven National Laboratory have developed a new electrocatalyst that uses a single layer of platinum and minimizes its wear and tear while maintaining high levels of reactivity during tests that mimic stop-and-go driving. The research - described online in Angewandte Chemie, International Edition, and identified by the journal as a "very important paper" - may greatly enhance the practicality of fuel-cell vehicles and may also be applicable for improving the performance of other metallic catalysts.

The newly designed catalysts are composed of a single layer of platinum over a palladium (or palladium-gold alloy) nanoparticle core. Their structural characterization was performed at Brookhaven's Center for Functional Nanomaterials www.bnl.gov/cfn/ and the National Synchrotron Light Source (www.nsls.bnl.gov/).

palladium nanoparticle

This high-angle annular dark field (HAADF) scanning transmission electron microscopy (STEM) image shows a bright shell on a relatively darker nanoparticle, signifying the formation of a core/shell structure — a platinum monolayer shell on a palladium nanoparticle core.
"Our studies of the structure and activity of this catalyst - and comparisons with platinum-carbon catalysts currently in use - illustrate that the palladium core 'protects' the fine layer of platinum surrounding the particles, enabling it to maintain reactivity for a much longer period of time," explained Brookhaven Lab chemist Radoslav Adzic, who leads the research team.

In conventional fuel-cell catalysts, the oxidation and reduction cycling - triggered by changes in voltage that occur during stop-and-go driving - damages the platinum. Over time, the platinum dissolves, causing irreversible damage to the fuel cell.

In the new catalyst, palladium from the core is more reactive than platinum in these oxidation and reduction reactions. Stability tests simulating fuel cell voltage cycling revealed that, after 100,000 potential cycles, a significant amount of palladium had been oxidized, dissolved, and migrated away from the cathode.
In the membrane between the cathode and anode, the dissolved palladium ions were reduced by hydrogen diffusing from the anode to form a "band," or dots.

In contrast, platinum was almost unaffected, except for a small contraction of the platinum monolayer. "This contraction of the platinum lattice makes the catalyst more active and the stability of the particles increases," Adzic said.

Reactivity of the platinum monolayer/palladium core catalyst also remained extremely high. It was reduced by merely 37 percent after 100,000 cycles.

Building on earlier work that illustrated how small amounts of gold can enhance catalytic activity, the scientists also developed a form of the platinum monolayer catalyst with a palladium-gold alloy core. The addition of gold further increased the stability of the electrocatalyst, which retained nearly 70 percent of reactivity after 200,000 cycles of testing.

"This indicates the excellent durability of this electrocatalyst, especially when compared with simpler platinum-carbon catalysts, which lose nearly 70 percent of their reactivity after much shorter cycling times. This level of activity and stability indicates that this is a practical catalyst. It exceeds the goal set by DOE for 2010-2015 and it can be used for automotive applications," Adzic said.

He noted that fuel cells made using the new catalyst would require only about 10 grams of platinum per car - and less than 20 grams of palladium. Currently, in catalytic convertors used to treat exhaust gases, 5 to 10 grams of platinum is used. Since fuel-cell-powered cars would emit no exhaust gases, there would be no need for such catalytic converters, and therefore no net increase in the amount of platinum used.

"In addition to developing electrocatalysts for automotive fuel cell applications, these findings indicate the broad applicability of platinum monolayer catalysts and the possibility of extending this concept to catalysts based on other noble metals," Adzic said. ###

The fundamental science leading to the development of the new electrocatalyst and early scale-up work was funded by the DOE Office of Science. Additional funding came from the Toyota Motor Corporation.

The Center for Functional Nanomaterials at Brookhaven National Laboratory is one of the five DOE Nanoscale Science Research Centers (NSRCs: nano.energy.gov), premier national user facilities for interdisciplinary research at the nanoscale. Together the NSRCs comprise a suite of complementary facilities that provide researchers with state-of-the-art capabilities to fabricate, process, characterize and model nanoscale materials, and constitute the largest infrastructure investment of the National Nanotechnology Initiative. The NSRCs are located at DOE's Argonne, Brookhaven, Lawrence Berkeley, Oak Ridge and Sandia and Los Alamos national laboratories.

Related Links
One of ten national laboratories overseen and primarily funded by the Office of Science of the U.S. Department of Energy (DOE), Brookhaven National Laboratory conducts research in the physical, biomedical, and environmental sciences, as well as in energy technologies and national security. Brookhaven Lab also builds and operates major scientific facilities available to university, industry and government researchers. Brookhaven is operated and managed for DOE's Office of Science by Brookhaven Science Associates, a limited-liability company founded by the Research Foundation of State University of New York on behalf of Stony Brook University, the largest academic user of Laboratory facilities, and Battelle, a nonprofit, applied science and technology organization.

Contact: Karen McNulty Walsh kmcnulty@bnl.gov 631-344-8350 DOE/Brookhaven National Laboratory

Sunday, November 28, 2010

CMOSAIC project with ETH Zurich and EPFL

CMOSAIC project with ETH Zurich and EPFL


A new technology for stacking several layers of microprocesssors, which is being developed at IBM Research - Zurich, to be used in the CMOSAIC project with ETH Zurich and EPFL. IBM scientists believe the design can boost the performance of computer chips by a factor 10. The team estimates that the first 3D chips will be implemented in supercomputers by 2015 with a novel internal cooling system fully operational by 2020, for even further improvements.

A sugar cubes are used for size comparison.

Photo credit Michael Lowry

IMAGE and TEXT CREDIT: By IBM Research - Zurich © Copyright All Rights Reserved.

New ultra-clean nanowires have great potential

New ultra-clean nanowires produced at the Nano-Science Center, University of Copenhagen will have a central role in the development of new high-efficiency solar cells and electronics on a nanometer scale. PhD student Peter Krogstrup, Niels Bohr Institute, in collaboration with a number of well-known researchers and the company SunFlake A/S, is behind the breakthrough. The new findings have recently been published in the prestigious journal Nano Letters.

Nanowires are one-dimensional structures with unique electrical and optical properties – a kind of building blocks, which researchers use to create nanoscale devices. In recent years, there has been a great deal of research into how nanowires can be used as building blocks in the development of solar cells. One of the challenges is controlling the production of nanowires. The new ultra-clean nanowires are part of the solution. Ultra clean means that the electronic structure is perfectly uniform throughout the nanowires, which is a very important part in obtaining nano-electronic devices of high performance. This is achieved by growing the wires without the use of a metal catalysis like gold, and at the same time having a perfect crystal of only one single structural phase which until now have been impossible for these types of nanowires.

GaAs nanowires

Illustration: Ultra-clean gallium-arsenid nanowires grown on a silicon substrate gives hope of developing cheap and very effective solar cells.
- The ultra-clean wires are grown on a silicon substrate with an extremely thin layer of natural oxide. The element Gallium, which is a part of the nanowire material, reacts with the oxide and makes small holes in the oxide layer, and here the gallium collects into small droplets of a few nanometers in thickness.
These droplets capture the element Arsenic – the other material in the nanowire and through a self-catalytic effect starts the growth of the nanowires without interference from other substances, explains Peter Krogstrup. The breakthrough is the result of a year's work in connection with his PhD.

Control over the cultivation of nanowires

Numerous experiments with different growing conditions have made the researchers wiser to physics behind the formation of the nanowires. A nanowire normally consists of both hexagonal and cubic crystal segments, but the new nanowires only consist of a perfect cubic crystal structure. This means that the path of the electrons through the wire is unaffected and thus suffers less energy loss which leads to a higher efficiency.

- This better understanding of the growing process gives us control over the cultivation of nanowires and the clean wires are the starting point for my current work developing a high efficiency solar cell based on nanowires. With these results we are a good step closer to this goal, explains Peter Krogstrup, pointing out that his nanowires are grown on a silicon substrate.

- The substrate is cheaper than the alternative substrates that many other researchers use. It is important because ultimately it is about getting as much energy as possible for as little cost as possible, explains Peter Krogstrup, whose research is conducted in collaboration with the company SunFlake A/S, which is located at the Nano-Science Center at the University of Copenhagen. The company is working to develop the solar cells of the future based on the nanostructures of Gallium and Arsenic.

- We are very pleased that Peter has delivered such good results so early in the research project, says the CEO of SunFlake A/S Morten Schaldemose. ###

Please contact: Peter Krogstrup: Phone: +45 26715191, email: pkrogstrup@gmail.com Rikke Bøyesen, communications: Phone: +45 28750413, email: rb@nano.ku.dk

Contact: Peter Krogstrup pkrogstrup@gmail.com 452-671-5191 University of Copenhagen>

Saturday, November 27, 2010

Unconventional idea for antiviral contraceptive gel wins Gates Foundation grant

A vaginal gel that affords both contraception and HIV protection using nanoparticles that carry bee venom is one of the bold, unconventional ideas that won a 2010 Grand Challenges Explorations grant from the Bill & Melinda Gates Foundation.

Grand Challenges Explorations is a Gates Foundation initiative to foster innovative projects in areas where unorthodox thinking is most urgently needed. Recipients receive grants to explore creative solutions to global health issues.

Sam Wickline, MD, professor of medicine, of cell biology and physiology, of physics and of biomedical engineering at Washington University School of Medicine in St. Louis is one of 65 scientists selected in November to participate in the grant program.

Wickline proposes to develop a contraceptive, antiviral gel containing trillions of nanoparticles that will target both HIV and sperm and deliver a bee venom toxin that will incapacitate them.


A computer simulation of a nanoparticle showing its core of perfluorocarbon (green) and its lipid coating (red, orange and blue).
"Sperm and HIV (the human immunodeficiency virus that can lead to acquired immune deficiency syndrome, or AIDS) are remarkably similar in their natural mechanism of genetic transmission," Wickline says. "Both need to fuse with their target cell in order to deliver their genetic payloads – DNA in the case of sperm, and RNA in the case of HIV."

Wickline's plan is to use the very means by which sperm and HIV operate to destroy them.

"The idea is to trick each to fuse with a synthetic Trojan Horse – a nanoparticle that will overwhelm sperm and HIV in numbers and in destructive power."
It is an unconventional and creative plan for sure, but it is grounded in proven technologies and research-based knowledge. If the idea shows promise, the initial seed money grant can lead to additional funding.

The Trojan Horse or decoy that will be used to attract the sperm and HIV is a lipid nanoparticle created by Wickline and colleague Gregory Lanza, MD, PhD, professor of medicine, that has already been proven safe for clinical use. Given the size of nanoparticles – spheres of around six millionths of an inch in diameter – "Trojan Pony" may be a better metaphor.

A toxin derived from the substance bees insert into their victims when they sting is the agent that will destroy the sperm and HIV. The toxin, called melittin, comprises more than half of the dry weight of the venom of the honeybee Apis mellifera.

The nanoparticles will carry a synthetic version of the toxin melittin to the targets.

"Cells readily take in melittin," Wickline says. "But once it gets in, it pokes holes in cell membranes destroy the cells."

A local biotech startup company, Kereos Inc., is testing melittin as an anti-cancer agent.

Since melittin can annihilate almost any cell, the trick is to target the melittin to the specific cells intended for destruction (cancer, sperm, HIV) without causing collateral damage to other cells in the body.

Wickline and colleague Paul Schlesinger, MD, PhD, associate professor of cell biology and physiology, attacked that problem two years ago when they developed "nanobees," the name coined for nanoparticles that sequester melittin so that it neither harms healthy tissue nor is degraded before it reaches the intended target.

Wickline and his colleagues have also developed the ability to add agents to the nanobees to cause them to home in on specific target cells. Although nanoparticles are a few thousand times smaller than the dot above an "i," each can carry hundreds of thousands of molecules on its surface.

"We have the ability to attach and swap in various specific targeting molecules to nanoparticles that will bind with receptors on the surface of selected cells," Wickline says. "This gives the particles the ability to home in on specific target cells."

To get the nanobees to hook up with sperm and offload their lethal cargo, Wickline intends to target a well-known "docking site" on the sperm cap. Sperm cells, which are roughly 160 times bigger than the 250-nanometer particles, will be swarmed with nanobees.

HIV virions (individual HIV particles), which are less than half the size of the nanoparticle, will be captured and destroyed with special molecules attached to the nanobees that bind to complementary molecules on the virion that play a role in initiating HIV fusion to cells.

Although these nanoparticles have been proven safe in the body, they are too large to move outside the vaginal vault, and will remain on site in surveillance for sperm and HIV until washed out by the body's natural fluids.

"We believe this can succeed because both sperm and HIV are built to target, fuse and discharge their cargo," Wickline says. "Our nanoparticles are similarly built to target, fuse and deliver their cargo. These attributes will enable a process of mutual assured destruction in a sequestered biological environment."

If successful, Wickline's idea could have enormous benefits for women, particularly in sub-Saharan Africa, a region that accounted for 68 percent of new HIV infections among adults in 2008. Women and girls in this area continue to be affected disproportionately – in some countries up to four times higher than males.

Sub-Saharan Africa also has the world's highest fertility rate -- 5.6 children per woman and twice the world average. The region's population is expected to increase to 1.6 billion people by 2050 unless women are empowered to prevent unwanted pregnancies.

A contributing factor to the vulnerability of women to both HIV and unintended pregnancy in sub-Saharan Africa is fear of violence from male partners if condom use is suggested. This technology could enable women to protect themselves without the need to seek approval from male partners.

While bringing the technology forward for clinical use by women would require many months of testing, the concept is supported by a recent trial of vaginal gel-based anti-HIV drugs in South African women. That study found that gel based delivery systems can substantially decrease the spread of AIDS with no harmful side effects.

Wickline has assembled a multidisciplinary team of collaborators to carry out the proof of concept activities that the grant funds. Kelle Moley, MD, professor of obstetrics and gynecology, will contribute expertise in reproductive biology; Lee Ratner, MD, PhD, professor of medicine, of molecular microbiology and of pathology and immunology, will serve as the authority on HIV and human retrovirus infections; Schlesinger will provide expertise in membrane biophysics; and Josh Hood, MD, PhD, instructor in medicine, providing expertise in immunological targeting. ###

Washington University School of Medicine's 2,100 employed and volunteer faculty physicians also are the medical staff of Barnes-Jewish and St. Louis Children's hospitals. The School of Medicine is one of the leading medical research, teaching and patient care institutions in the nation, currently ranked fourth in the nation by U.S. News & World Report. Through its affiliations with Barnes-Jewish and St. Louis Children's hospitals, the School of Medicine is linked to BJC HealthCare.

Contact: Joni Westerhouse westerhousej@wustl.edu 314-286-0120 Washington University in St. Louis

Friday, November 26, 2010

Boris Fritz on "Nanotechnology: Today's Tomorrow" VIDEO

Boris Fritz, an aerospace engineer with Northrop Grumman with a quarter-century of experience, holder of three patents, founded the Society of Manufacturing Engineers Nanomanufacturing Technical Group. He projects us into a future where virtual reality is real reality -- programmable material used to build homes that can be "remodeled" at will with holodeck-like rooms where interiors can reshape themselves, furnished with volumetric pixels that conform to user's needs -- a bed at night - desk or kitchen table during the day. Molecular-sized machines will produce "respirocytes"that will allow us go without a fresh intake of oxygen for four hours. This will take your breath away!

TEXT and VIDEO CREDIT: msheerin67

Lab on chip for membrane proteins

Nanopore array allows simultanous tests in search for new drugs.

Membrane-associated receptors, channels and transporters are among the most important drug targets for the pharmaceutical industry. The search for new drugs resembles looking for a needle in a haystack. Therefore new analytical techniques are required which facilitate the simultaneous screening of a large library of compounds across a variety of membrane proteins. However, this class of methods is still at the early stages of development. The group of Prof. Dr. Robert Tampé, in collaboration with the Walter Schottky Institute at Technical University Munich, has now presented a novel, automatable lab-on-chip device for high-throughput screening of sensitive membrane proteins.

The work is detailed in the journal Nano Letters, where the scientists describe the analysis of membrane proteins on a nano-fabricated chip surface that contains almost 50,000 nanopores. These pores are covered by a freely suspended lipid membrane that incorporates the proteins to be analyzed. Because the lipid membrane is free of organic solvents and the proteins do not touch the solid support, the fragile structure (and therefore function) of the proteins is preserved.

Fluorescence-Labeled Compounds

Caption: The transport of fluorescence-labeled compounds across the lipid membrane can be monitored in real-time by accumulation or release from micro-compartments on the chip. Each nanopore is connected individually to one such compartment. Hence, one can analyze thousands of different drug compounds on a single chip.

Credit: Institute for Biochemistry, Goethe-University, Frankfurt, Germany. Usage Restrictions: None.
The system can be used to monitor the transport kinetics of membrane proteins by fluorescence microscopy. Due to the parallel design of the nanopore chip, a large number of samples can be analyzed simultaneously. ###

Publication: Alexander Kleefen et al.: Multiplexed Parallel Single Transport Recordings on Nanopore Arrays, Nano Lett. [Epub ahead of print]PMID: 20979410 [PubMed - as supplied by publisher] DOI: 10.1021/nl1033528
Contact: Prof. Robert Tampé tampe@em.uni-frankfurt.de 49-697-982-9475 Goethe University Frankfurt

Wednesday, November 24, 2010

Nanogenerators grow strong enough to power small conventional electronics VIDEO

Energy harvesting: Blinking numbers on a liquid-crystal display (LCD) often indicate that a device's clock needs resetting. But in the laboratory of Zhong Lin Wang at Georgia Tech, the blinking number on a small LCD signals the success of a five-year effort to power conventional electronic devices with nanoscale generators that harvest mechanical energy from the environment using an array of tiny nanowires.

In this case, the mechanical energy comes from compressing a nanogenerator between two fingers, but it could also come from a heartbeat, the pounding of a hiker's shoe on a trail, the rustling of a shirt, or the vibration of a heavy machine. While these nanogenerators will never produce large amounts of electricity for conventional purposes, they could be used to power nanoscale and microscale devices – and even to recharge pacemakers or iPods.

Wang's nanogenerators rely on the piezoelectric effect seen in crystalline materials such as zinc oxide, in which an electric charge potential is created when structures made from the material are flexed or compressed. By capturing and combining the charges from millions of these nanoscale zinc oxide wires, Wang and his research team can produce as much as three volts – and up to 300 nanoamps.

Caption: In the laboratory of Zhong Lin Wang at Georgia Tech, a blinking LCD signals the success of a five-year effort to power conventional electronic devices using nanoscale generators that harvest mechanical energy from the environment.

Credit: Georgia Tech. Usage Restrictions: None.

Powering LCD

Caption: Compressing a nanogenerator between two fingers is enough to drive a liquid-crystal display.

Credit: Courtesy Zhong Lin Wang. Usage Restrictions: None.
"By simplifying our design, making it more robust and integrating the contributions from many more nanowires, we have successfully boosted the output of our nanogenerator enough to drive devices such as commercial liquid-crystal displays, light-emitting diodes and laser diodes," said Wang, a Regents' professor in Georgia Tech's School of Materials Science and Engineering. "If we can sustain this rate of improvement, we will reach some true applications in healthcare devices, personal electronics, or environmental monitoring."

Recent improvements in the nanogenerators, including a simpler fabrication technique, were reported online last week in the journal Nano Letters. Earlier papers in the same journal and in Nature Communications reported other advances for the work, which has been supported by the Defense Advanced Research Projects Agency (DARPA), the U.S. Department of Energy, the U.S. Air Force, and the National Science Foundation.

"We are interested in very small devices that can be used in applications such as health care, environmental monitoring and personal electronics," said Wang. "How to power these devices is a critical issue."

The earliest zinc oxide nanogenerators used arrays of nanowires grown on a rigid substrate and topped with a metal electrode. Later versions embedded both ends of the nanowires in polymer and produced power by simple flexing. Regardless of the configuration, the devices required careful growth of the nanowire arrays and painstaking assembly.
In the latest paper, Wang and his group members Youfan Hu, Yan Zhang, Chen Xu, Guang Zhu and Zetang Li reported on much simpler fabrication techniques. First, they grew arrays of a new type of nanowire that has a conical shape. These wires were cut from their growth substrate and placed into an alcohol solution.

The solution containing the nanowires was then dripped onto a thin metal electrode and a sheet of flexible polymer film. After the alcohol was allowed to dry, another layer was created. Multiple nanowire/polymer layers were built up into a kind of composite, using a process that Wang believes could be scaled up to industrial production.

When flexed, these nanowire sandwiches – which are about two centimeters by 1.5 centimeters – generated enough power to drive a commercial display borrowed from a pocket calculator.

Wang says the nanogenerators are now close to producing enough current for a self-powered system that might monitor the environment for a toxic gas, for instance, then broadcast a warning. The system would include capacitors able to store up the small charges until enough power was available to send out a burst of data.

While even the current nanogenerator output remains below the level required for such devices as iPods or cardiac pacemakers, Wang believes those levels will be reached within three to five years. The current nanogenerator, he notes, is nearly 100 times more powerful than what his group had developed just a year ago.

Writing in a separate paper published in October in the journal Nature Communications, group members Sheng Xu, Benjamin J. Hansen and Wang reported on a new technique for fabricating piezoelectric nanowires from lead zirconate titanate – also known as PZT. The material is already used industrially, but is difficult to grow because it requires temperatures of 650 degrees Celsius.

In the paper, Wang's team reported the first chemical epitaxial growth of vertically-aligned single-crystal nanowire arrays of PZT on a variety of conductive and non-conductive substrates. They used a process known as hydrothermal decomposition, which took place at just 230 degrees Celsius.

With a rectifying circuit to convert alternating current to direct current, the researchers used the PZT nanogenerators to power a commercial laser diode, demonstrating an alternative materials system for Wang's nanogenerator family. "This allows us the flexibility of choosing the best material and process for the given need, although the performance of PZT is not as good as zinc oxide for power generation," he explained.

And in another paper published in Nano Letters, Wang and group members Guang Zhu, Rusen Yang and Sihong Wang reported on yet another advance boosting nanogenerator output. Their approach, called "scalable sweeping printing," includes a two-step process of (1) transferring vertically-aligned zinc oxide nanowires to a polymer receiving substrate to form horizontal arrays and (2) applying parallel strip electrodes to connect all of the nanowires together.

Using a single layer of this structure, the researchers produced an open-circuit voltage of 2.03 volts and a peak output power density of approximately 11 milliwatts per cubic centimeter.

"From when we got started in 2005 until today, we have dramatically improved the output of our nanogenerators," Wang noted. "We are within the range of what's needed. If we can drive these small components, I believe we will be able to power small systems in the near future. In the next five years, I hope to see this move into application." ###

Contact: John Toon jtoon@gatech.edu 404-894-6986 Georgia Institute of Technology Research News

Monday, November 22, 2010

Iowa State, Ames Laboratory scientists advance the understanding of the big getting bigger

AMES, Iowa – Patricia Thiel of Iowa State University and the Ames Laboratory put a box of tissues to the right, a stack of coasters to the middle and a trinket box to the left.

"Nature," she said of her table-top illustration, "doesn't want lots of little things." So Thiel grabbed the smaller things and slid them into a single pile next to the bigger tissue box. "Nature wants one big thing all together, like this."

Thiel, an Iowa State Distinguished Professor of Chemistry and a faculty scientist for the U.S. Department of Energy's Ames Laboratory, and James Evans, an Iowa State professor of physics and astronomy and a faculty scientist for the Ames Laboratory, describe that process in the Oct. 29 issue of the journal Science.

The paper, "A Little Chemistry Helps the Big Get Bigger," is in the journal's Perspectives section. It describes a process called coarsening. That's when "a group of objects of different sizes transforms into fewer objects with larger average size, such that 'the big get bigger,'" says the paper. Examples of the process include the geologic formation of gemstones, the degradation of pharmaceutical suspensions and the manufacture of structural steels.

James Evans Patricia Thiel Iowa State University

Caption: James Evans and Patricia Thiel, of Iowa State University and the US Department of Energy's Ames Laboratory, are using scanning tunneling microscope technology to study coarsening. Understanding the process could improve the stability of nanoscale technologies.

Credit: Photo by Bob Elbert/Iowa State University. Usage Restrictions: None.
Thiel and Evans were invited to write the paper after Thiel delivered a talk at an American Chemical Society meeting about their studies of coarsening, an emerging field in surface chemistry.

Thiel worked with Mingmin Shen, a former Iowa State doctoral student who is now a post-doctoral research associate at Pacific Northwest National Laboratory in Richland, Wash., on the experimental side of the coarsening research. Evans worked with Da-Jiang Liu, an associate scientist at the Ames Laboratory, on the theoretical side of the project.
The researchers, with the support of grants from the National Science Foundation, have been using scanning tunneling microscope technology – an instrument that allows them to see individual atoms – to study how coarsening happens on the surface of objects.

They've studied nanoscale particles grown on the surface of silver and how adding sulfur can increase coarsening. They're trying to learn the mechanism of that increase and understand the nature of the messengers that move atoms during the coarsening process.

What Thiel and Evans are looking for is a general principle that explains what they call additive-enhanced coarsening. To do that, Thiel said they still need to collect and analyze data from more coarsening systems.

Evans said a better understanding of the coarsening process can help researchers develop small structures – including nanoscale technologies, catalysts or drug suspensions – that resist coarsening and are therefore more durable. A better understanding could also help researchers manipulate coarsening to develop structures with a very narrow distribution of particle sizes, something important to some nanotechnologies.

"When we're building something on a small scale, for it to be useful, it has to be robust, it has to survive," Evans said. "And one thing we're looking at is the stability of the very tiny structures that are crucial to nanoscale technologies." ###

Contact: Patricia Thiel thiel@ameslab.gov 515-294-8985 Iowa State University

Sunday, November 21, 2010

Transparent Conductive Material Could Lead to Power-Generating Windows

Combines elements for light harvesting and electric charge transport over large, transparent areas.

UPTON, NY — Scientists at the U.S. Department of Energy’s (DOE) Brookhaven National Laboratory and Los Alamos National Laboratory have fabricated transparent thin films capable of absorbing light and generating electric charge over a relatively large area. The material, described in the journal Chemistry of Materials, could be used to develop transparent solar panels or even windows that absorb solar energy to generate electricity.

The material consists of a semiconducting polymer doped with carbon-rich fullerenes. Under carefully controlled conditions, the material self-assembles to form a reproducible pattern of micron-size hexagon-shaped cells over a relatively large area (up to several millimeters).

“Though such honeycomb-patterned thin films have previously been made using conventional polymers like polystyrene, this is the first report of such a material that blends semiconductors and fullerenes to absorb light and efficiently generate charge and charge separation,” said lead scientist Mircea Cotlet, a physical chemist at Brookhaven’s Center for Functional Nanomaterials (CFN).

conjugated polymer (PPV) honeycomb

Top: Scanning electron microscopy image and zoom of conjugated polymer (PPV) honeycomb. Bottom (left-to-right): Confocal fluorescence lifetime images of conjugated honeycomb, of polymer/fullerene honeycomb double layer and of polymer/fullerene honeycomb blend. Efficient charge transfer within the whole framework is observed in the case of polymer/fullerene honeycomb blend as a dramatic reduction in the fluorescence lifetime.
Furthermore, the material remains largely transparent because the polymer chains pack densely only at the edges of the hexagons, while remaining loosely packed and spread very thin across the centers. “The densely packed edges strongly absorb light and may also facilitate conducting electricity,” Cotlet explained, “while the centers do not absorb much light and are relatively transparent.”

“Combining these traits and achieving large-scale patterning could enable a wide range of practical applications, such as energy-generating solar windows, transparent solar panels, and new kinds of optical displays,” said co-author Zhihua Xu, a materials scientist at the CFN.

“Imagine a house with windows made of this kind of material, which, combined with a solar roof, would cut its electricity costs significantly. This is pretty exciting,” Cotlet said.
The scientists fabricated the honeycomb thin films by creating a flow of micrometer-size water droplets across a thin layer of the polymer/fullerene blend solution. These water droplets self-assembled into large arrays within the polymer solution. As the solvent completely evaporates, the polymer forms a hexagonal honeycomb pattern over a large area.

“This is a cost-effective method, with potential to be scaled up from the laboratory to industrial-scale production,” Xu said.

The scientists verified the uniformity of the honeycomb structure with various scanning probe and electron microscopy techniques, and tested the optical properties and charge generation at various parts of the honeycomb structure (edges, centers, and nodes where individual cells connect) using time-resolved confocal fluorescence microscopy.

The scientists also found that the degree of polymer packing was determined by the rate of solvent evaporation, which in turn determines the rate of charge transport through the material.

“The slower the solvent evaporates, the more tightly packed the polymer, and the better the charge transport,” Cotlet said.

“Our work provides a deeper understanding of the optical properties of the honeycomb structure. The next step will be to use these honeycomb thin films to fabricate transparent and flexible organic solar cells and other devices,” he said.

The research was supported at Los Alamos by the DOE Office of Science. The work was also carried out in part at the CFN and the Center for Integrated Nanotechnologies Gateway to Los Alamos facility. The Brookhaven team included Mircea Cotlet, Zhihua Xu, and Ranjith Krishna Pai. Collaborators from Los Alamos include Hsing-Lin Wang and Hsinhan Tsai, who are both users of the CFN facilities at Brookhaven, Andrew Dattelbaum from the Center for Integrated Nanotechnologies Gateway to Los Alamos facility, and project leader Andrew Shreve of the Materials Physics and Applications Division.

The Center for Functional Nanomaterials at Brookhaven National Laboratory and the Center for Integrated Nanotechnologies Gateway to Los Alamos facility are two of the five DOE Nanoscale Science Research Centers (NSRCs), premier national user facilities for interdisciplinary research at the nanoscale. Together the NSRCs comprise a suite of complementary facilities that provide researchers with state-of-the-art capabilities to fabricate, process, characterize and model nanoscale materials, and constitute the largest infrastructure investment of the National Nanotechnology Initiative. The NSRCs are located at DOE’s Argonne, Brookhaven, Lawrence Berkeley, Oak Ridge and Sandia and Los Alamos national laboratories.

Contact: Karen McNulty Walsh kmcnulty@bnl.gov 631-344-8350 DOE/Brookhaven National Laboratory

Thursday, November 18, 2010

Nanoimprint lithography NSF grant awarded to micro device lab at Stevens

Dr. Eui-Hyeok Yang, Associate Professor of Mechanical Engineering and Director of the Micro Device Laboratory (MDL) at Stevens Institute of Technology, The Innovation University (TM), will receive funding from the National Science Foundation (NSF) for the acquisition of a Nanoimprint Lithography System (NIL) for the purpose of nanoscience research and education based on low-dimensional materials at Stevens. The Co-PIs of the project are Drs. Besser, Choi, Cappelleri and Strauf. This equipment acquisition is an important step in achieving Dr. Yang's goal of integrating research and education in nanotechnology at the MDL. In addition, nanoimprint lithography will benefit local institutions searching for nearby solutions for nanopatterning. "The system will be an open local resource for researchers," Yang says.

"The NIL system is the latest piece of equipment in completing the fabrication process flow for micro/nano devices at Stevens," Yang says. "The MDL's capabilities for research and education increase significantly with this system."

The grant funds the acquisition of a Nanonex 1000 Nanoimprint Lithography System, a whole-wafer (4-inch) nanoimprinter for thermoplastic resins that has high-resolution (~10 nm) and high-throughput (~60 sec) capabilities.

Dr. Eu-Hyeok (EH) Yang This acquisition will strengthen the exploration of high-throughput nanoscale patterning as a key part of the research projects funded by NSF, DARPA, US Army, AFOSR, and ONR. These inter-disciplinary, high-risk, high-payoff research projects will provide a consistently growing user base and cultivate a multidisciplinary research-intense learning environment in nanotechnology at Stevens along with collaborators in the New York City metropolitan area.
This research capability also supports cross-disciplinary educational initiatives already underway at Stevens. It provides hands-on experience to students in the Nanotechnology Graduate Program and undergraduates alike. One of Yang's undergraduate senior design teams plans create an Intra Ocular Pressure Relief Valve, used to treat glaucoma by releasing fluid when pressure builds up in the eye. The nanoimprint lithography system will greatly benefit their fabrication process.

"The MDL is an integral component of the Nanotechnology research thrust at Stevens," says Michael Bruno, Dean of the Charles. V. Schaefer School of Engineering and Science. "The NIL acquisition enhances Stevens' capabilities for nanotechnology research in the area and simultaneously offers outside organizations a solution for their nanotechnology research needs."

Researchers at Stevens previously relied on an external nanoimprint lithography facility at the Center for Functional Nanomaterials (CFN) at the Brookhaven National Laboratory in Upton, NY. Therefore, the availability of the in-house nanoimprint lithography system will significantly increase the efficiency and output of work done in the laboratory, increase the training capabilities for Stevens staff and students, and enable many undergraduate and graduate educational initiatives. Investigators from and outside of Stevens will have easy access to nanoimprint lithography in the Micro Device Laboratory on the Stevens campus. Professor Ioana Voiculescu at City College of New York is listed as Senior Personnel of the Project.

Nanotechnology brings together professors from five different programs in the Charles V.Schaefer, Jr. School of Engineering and Sciences: Chemical, Chemical Biology, and Biomedical Engineering; Civil, Environmental, and Ocean Engineering; Mechanical Engineering; Chemical Engineering and Material Science; and Physics and Engineering Physics.

"Over the next few years we will be a major force in nanotechnology research as this facility, along with future acquisitions, continues to grow," says Dr. Constantin Chassapis, Professor, Deputy Dean of the School of Engineering & Science, and Director of the Department of Mechanical Engineering. ###

Contact: Dr. Eui-Hyeok (EH) Yang eyang@stevens.edu 201-216-5574 Stevens Institute of Technology

Wednesday, November 17, 2010

Microfluidics-imaging platform detects cancer growth signaling in minute biopsy samples

Inappropriate growth and survival signaling, which leads to the aberrant growth of cancer cells, is a driving force behind tumors. Much of current cancer research focuses on the kinase enzymes whose mutations are responsible for such disregulated signaling, and many successful molecularly targeted anti-cancer therapeutics are directed at inhibiting kinase activity.

Now, UCLA researchers from the Crump Institute for Molecular Imaging, the Institute for Molecular Medicine, the California NanoSystems Institute, the Jonsson Comprehensive Cancer Center and the department of molecular and medical pharmacology have developed an in vitro method for assessing kinase activity in minute tissue samples from patients. The method involves an integrated microfluidics and imaging platform that can reproducibly measure kinase enzymatic activity from as few as 3,000 cells.

In a paper published Nov. 1 in the journal Cancer Research, the UCLA researchers describe several new technological advances in microfluidics and imaging detection they co-developed to measure kinase activity in small-input samples. The team applied their microfluidic kinase assay to human leukemia patient samples.

Thomas Graeber

Thomas Graeber
"Because the device requires only a very small tissue sample to give results, this method creates new potential for direct kinase experimentation and diagnostics on patient blood, bone marrow and needle biopsy samples," said lead investigator Thomas Graeber, a UCLA professor of molecular and medical pharmacology. "For example, the stem cell properties of leukemia can be directly studied from patient samples."

To improve radio-signal detection, the team used a novel imaging detector, in the form of a solid-state beta camera, which can sensitively detect and spatially resolve radioactive signal directly from a microfluidic chip.
The beta camera provides a picture of the activity on the chip, allowing real-time monitoring of the assay performance and outcome. It is highly sensitive and quantitative.

In their first application of the device, the team measured the activity of the mutated kinase responsible for chronic myelogenous leukemia. This mutation is targeted by the clinically successful kinase inhibitor Gleevec.

"We are not aware of other work demonstrating solid-state integrated radioactive imaging from a microfluidic platform," said co-investigator Arion Chatziioannou, a UCLA professor of molecular and medical pharmacology.

The resulting microfluidic in vitro kinase radioassay improves reaction efficiency, compared with standard assays, and can be processed in much less time. This greater efficiency, coupled with the high sensitivity of the beta camera, reduces the amount of sample cell input by two to three orders of magnitude, compared with conventional and 96-well assays. The assay includes a kinase immunocapture step to increase specificity towards the kinase of interest.

"To get the kinase assay to work in a microfluidic environment, we needed to develop new protocols and reagents for efficiently manipulating solid-support kinase capture beads using microfluidic trap-and-release valves," said co-investigator Hsian-Rong Tseng , a UCLA professor of molecular and medical pharmacology.

"Integration of the solid-state beta camera allows researchers to monitor the assay in real time, which proved useful during our protocol development and testing," said Cong Fang, the leading graduate student on the project. "The integrated microfluidic and imaging platform opens new possibilities and makes miniaturization of many common radioactivity-based bioassays to the microfluidic realm possible."

"With the integration of the compact camera, the microfluidic format assay has the potential to be developed into inexpensive bench-top, stand-alone units," said UCLA postdoctoral fellow Nam Vu, who led the imaging development.

"Taken together, the reduced sample input required, the decreased assay time, and the digitally controlled reproducibility of the team's microfluidic kinase radioassay facilitates direct experimentation on clinical samples that are either precious or perishable," said UCLA postdoctoral fellow Yanju Wang, who led the design of the network of microfluidic components that run the assay.

Future experiments will develop reproducible sample collection and measurement conditions for primary patient samples.

Other applications could include profiling of patient and animal model samples for their kinase-inhibitor drug sensitivity, or measurement of kinase activity from stem cells, cancer stem cells and other rare immune cells.

The research team included collaborators from Children's Hospital Los Angeles' division of hematology and oncology and the University of Southern California.

The California NanoSystems Institute at UCLA is an integrated research facility located at UCLA and UC Santa Barbara. Its mission is to foster interdisciplinary collaborations in nanoscience and nanotechnology; to train a new generation of scientists, educators and technology leaders; to generate partnerships with industry; and to contribute to the economic development and the social well-being of California, the United States and the world. The CNSI was established in 2000 with $100 million from the state of California. An additional $850 million of support has come from federal research grants and industry funding. CNSI members are drawn from UCLA's College of Letters and Science, the David Geffen School of Medicine, the School of Dentistry, the School of Public Health and the Henry Samueli School of Engineering and Applied Science. They are engaged in measuring, modifying and manipulating atoms and molecules — the building blocks of our world. Their work is carried out in an integrated laboratory environment. This dynamic research setting has enhanced understanding of phenomena at the nanoscale and promises to produce important discoveries in health, energy, the environment and information technology.

Tuesday, November 16, 2010

Advance could change modern electronics

CORVALLIS, Ore. – Researchers at Oregon State University have solved a quest in fundamental material science that has eluded scientists since the 1960s, and could form the basis of a new approach to electronics.

The discovery, just reported online in the professional journal Advanced Materials, outlines the creation for the first time of a high-performance "metal-insulator-metal" diode.

"Researchers have been trying to do this for decades, until now without success," said Douglas Keszler, a distinguished professor of chemistry at OSU and one of the nation's leading material science researchers. "Diodes made previously with other approaches always had poor yield and performance.

"This is a fundamental change in the way you could produce electronic products, at high speed on a huge scale at very low cost, even less than with conventional methods," Keszler said. "It's a basic way to eliminate the current speed limitations of electrons that have to move through materials."

MIM diode

This image of an asymmetric MIM diode reflects a major advance in materials science that could lead to less costly and higher speed electronic products. (Image courtesy of Oregon State University)
A patent has been applied for on the new technology, university officials say. New companies, industries and high-tech jobs may ultimately emerge from this advance, they say.

The research was done in the Center for Green Materials Chemistry, and has been supported by the National Science Foundation, the Army Research Laboratory and the Oregon Nanoscience and Microtechnologies Institute.

Conventional electronics made with silicon-based materials work with transistors that help control the flow of electrons. Although fast and comparatively inexpensive, this approach is still limited by the speed with which electrons can move through these materials.
And with the advent of ever-faster computers and more sophisticated products such as liquid crystal displays, current technologies are nearing the limit of what they can do, experts say.

By contrast, a metal-insulator-metal, or MIM diode can be used to perform some of the same functions, but in a fundamentally different way. In this system, the device is like a sandwich, with the insulator in the middle and two layers of metal above and below it. In order to function, the electron doesn't so much move through the materials as it "tunnels" through the insulator – almost instantaneously appearing on the other side.

"When they first started to develop more sophisticated materials for the display industry, they knew this type of MIM diode was what they needed, but they couldn't make it work," Keszler said. "Now we can, and it could probably be used with a range of metals that are inexpensive and easily available, like copper, nickel or aluminum. It's also much simpler, less costly and easier to fabricate."

The findings were made by researchers in the OSU Department of Chemistry; School of Electrical Engineering and Computer Science; and School of Mechanical, Industrial and Manufacturing Engineering.

In the new study, the OSU scientists and engineers describe use of an "amorphous metal contact" as a technology that solves problems that previously plagued MIM diodes. The OSU diodes were made at relatively low temperatures with techniques that would lend themselves to manufacture of devices on a variety of substrates over large areas.

OSU researchers have been leaders in a number of important material science advances in recent years, including the field of transparent electronics. University scientists will do some initial work with the new technology in electronic displays, but many applications are possible, they say.

High speed computers and electronics that don't depend on transistors are possibilities. Also on the horizon are "energy harvesting" technologies such as the nighttime capture of re-radiated solar energy, a way to produce energy from the Earth as it cools during the night.

"For a long time, everyone has wanted something that takes us beyond silicon," Keszler said. "This could be a way to simply print electronics on a huge size scale even less expensively than we can now. And when the products begin to emerge the increase in speed of operation could be enormous." ###

Contact: Douglas Keszler douglas.keszler@oregonstate.edu 541-737-6736 Oregon State University

Monday, November 15, 2010

NIH renews Nanomedicine Center focused on treating single-gene disorders for $16.1 million

The Georgia Tech-led Nanomedicine Center for Nucleoprotein Machines has received an award of $16.1 million for five years as part of its renewal by the National Institutes of Health (NIH). The eight-institution research team plans to pursue development of a clinically viable gene correction technology for single-gene disorders and demonstrate the technology's efficacy with sickle cell disease.

Sickle cell disease is a genetic condition present at birth that affects more than 70,000 Americans. It involves a single altered gene that produces abnormal hemoglobin — the protein that carries oxygen in the blood. In sickle cell disease, red blood cells become hard, sticky and "C" shaped. Sickle cells die early, which causes a constant shortage of red blood cells. The abnormal cells also clog the flow in small blood vessels, causing chronic pain and other serious problems such as infections and acute chest syndrome.

"Even though researchers know sickle cell disease is caused by a single A to T mutation in the beta-globin gene, there is no widely available cure," said center director Gang Bao, the Robert A. Milton Chair in Biomedical Engineering in the Wallace H. Coulter Department of Biomedical Engineering at Georgia Tech and Emory University. "By directly and precisely fixing the single mutation, we hope to reduce or eliminate the sickle cell population in an individual's blood stream and replace the sickle cells with healthy red blood cells."

Gang Bao, Georgia Institute of Technology

Caption: Gang Bao (right) is director of the Georgia Tech-led Nanomedicine Center for Nucleoprotein Machines, which received an award of $16.1 million for five years as part of its renewal by the National Institutes of Health.

Credit: Georgia Tech/Rob Felt. Usage Restrictions: None.
The center is one of eight NIH Nanomedicine Development Centers established in 2005 and 2006, a key initiative of the NIH's long-term nanomedicine research goals. The centers have highly multidisciplinary scientific teams that include biologists, physicians, mathematicians, engineers and computer scientists. Through an intense competition, the NIH selected four centers for second phase funding, including the one led by Georgia Tech.

In addition to experts in the Coulter Department of Biomedical Engineering at Georgia Tech and Emory University and the School of Chemical & Biomolecular Engineering at Georgia Tech,
researchers from Medical College of Georgia, Cold Spring Harbor Laboratory, New York University Medical Center, Massachusetts Institute of Technology, Stanford University and Harvard University are also members of the center.

The gene correction approach proposed by the research team to treat sickle cell disease involves delivering engineered zinc finger nucleases (ZFNs) -- genetic scissors that cut DNA at a specific site -- and DNA correction templates into the nuclei of hematopoietic stem cells isolated from the bone marrow of individuals with sickle cell disease. The researchers chose hematopoietic stem cells because they are the precursors of all blood cells, including the cells rendered dysfunctional in sickle cell patients. Hematopoietic stem cells possess such potent regenerative potential that transplantation of even a single hematopoietic stem cell is sufficient to rebuild the entire blood system of an organism.

The researchers plan to engineer and optimize the ZFN proteins so they will induce a double-strand break in the DNA near the sickle cell disease mutation, thereby activating the gene for correction. The broken DNA ends will enter the homologous recombination repair pathway, which will use the genetic information provided by the donor template -- rather than the original flawed information -- to correct the mutation. When the gene-corrected hematopoietic stem cells are injected back in the body, they will produce healthy red blood cells to replace the sickle cells.

"This approach represents a significant paradigm shift in current gene targeting and gene therapy technology in that no viral-based vector or foreign DNA is used," explained Bao, who is also a Georgia Tech College of Engineering Distinguished Professor. "We think it's a promising approach because we do not need to fix all of the mutations in all cells; we only need to greatly reduce the sickle cell population by replacing those cells with healthy red blood cells."

There are significant challenges in achieving the goals of the center, including the need to dramatically increase the rate of homologous recombination-mediated gene correction, improve the activity and specificity of ZFNs to maximize gene correction efficiency and minimize potentially harmful off-target effects, deliver the components necessary for gene correction to hematopoietic stem cells with high efficiency and throughput, avoid unwanted genomic rearrangements and optimize the engraftment of ZFN-modified hematopoietic stem cells.

To increase the efficiency of gene correction in the hematopoietic stem cells, the proposed gene correction approach will require a shift in repair pathway choice from non-homologous end joining toward homologous recombination. To accomplish this, the researchers plan to use methods they developed in the last four years to visualize the assembly of repair complexes at double-strand break sites and develop interventions to shift pathway choice toward homologous recombination.

To control ZFN activity so that unwanted off-target effects or gene rearrangements can be minimized or avoided, the researchers plan to refine and optimize the design and production of the proteins and develop photoactivatable proteins for better temporal control of ZFN activity. In addition, by investigating the fate and dynamics of the engineered proteins and donor template in living cells, and the incidence and biological effects of undesired mutations and gene rearrangements, the research team will further improve the process.

With novel imaging probes and methods already developed in the Nanomedicine Center for Nucleoprotein Machines, the researchers will be able to observe and systematically optimize each step in the gene correction process. Once that is accomplished, the research team will demonstrate the gene correction approach in a mouse model of sickle cell disease. Their goal is to demonstrate that gene-corrected cells can reconstitute the mouse hematopoietic system and reverse the sickle cell disease phenotype, according to Bao.

"We want to focus on sickle cell disease to demonstrate this approach, but if we are successful, the same approach can be adopted to treat some of the other 6,000 estimated single gene disorders in the world today, such as cystic fibrosis and Tay-Sachs," noted Bao. ###

Contact: Abby Vogel Robinson abby@innovate.gatech.edu 404-385-3364 Georgia Institute of Technology Research News

Sunday, November 14, 2010

Researchers find 'Goldilocks' of DNA self-assembly VIDEO

Researchers from North Carolina State University have found a way to optimize the development of DNA self-assembling materials, which hold promise for technologies ranging from drug delivery to molecular sensors. The key to the advance is the discovery of the "Goldilocks" length for DNA strands used in self-assembly – not too long, not too short, but just right.

DNA strands contain genetic coding that will form bonds with another strand that contains a unique sequence of complementary genes. By coating a material with a specific DNA layer, that material will then seek out and bond with its complementary counterpart. This concept, known as DNA-assisted self-assembly, creates significant opportunities in the biomedical and materials science fields, because it may allow the creation of self-assembling materials with a variety of applications.

But, while DNA self-assembly technology is not a new concept, it has historically faced some significant stumbling blocks. One of these obstacles has been that DNA segments that are too short often failed to self-assemble, while segments that are too long often led to the creation of deformed materials. This hurdle can lead to basic manufacturing problems, as well as significant changes in the properties of the material itself.

Caption: These "dancing" DNA strands are part of a computer simulation showing the molecular dynamics trajectory of DNA strands that exhibit best efficiency for hybridization. It represents a significant advance in the field of DNA self-assembling materials.

Credit: Abhishek Singh, North Carolina State University. Usage Restrictions: Video credit must be given.

DNA Strands

Caption: This image is a simulation snapshot of the molecular dynamics of DNA strands.

Credit: Abhishek Singh, North Carolina State University. Usage Restrictions: Image credit must be given.
A team of researchers from NC State and the University of Melbourne have proposed a solution to this problem, using computer simulations of DNA strands to identify the optimal length of a DNA strand for self-assembly – and explaining the scientific principles behind it.

"Strands that are too short or long form self-protected motifs," says Dr. Yara Yingling, an assistant professor of materials science and engineering at NC State and co-author of a paper describing the research. That means that the strands bond to each other, rather than to "partner" materials.

"The optimal lengths are not long enough to intertwine with each other, and are not short enough to fold over on themselves," Yingling explains. That leaves them exposed, and available to bond with the materials in another layer – the perfect situation for DNA self-assembly.

One potential application for such self-assembling materials is the development of drug-delivery vehicles. For example, researchers at the University of Melbourne have created self-assembling DNA capsules that are fully biocompatible, biodegradable and capable of releasing the drug when they come in contact with a specific physical stimulus – making them ideal for drug delivery.
DNA self-assembly technology is also expected to facilitate the creation of molecular sensors that use DNA to detect, and signal the presence of, clinically important biological molecules – which could have significant diagnostic applications in the medical field.

"We're now planning to explore additional factors that play a role in DNA self-assembly," Yingling says, "including temperature, genetic sequence and the environment in which the assembly takes place." ###

The paper, "Effect of Oligonucleotide Length on the Assembly of DNA Materials: Molecular Dynamics Simulations of Layer-by-Layer DNA Films," was published online Oct. 12 by the journal Langmuir. Lead author of the paper is Abhishek Singh, a Ph.D. student at NC State. Co-authors include Yingling; former NC State post-doctoral research associate Dr. Stacy Snyder; and Drs. Frank Caruso, Lillian Lee and Angus Johnston of the University of Melbourne. The work was supported by funding from NC State and the Australian Research Council.

Contact: Matt Shipman matt_shipman@ncsu.edu 919-515-6386 North Carolina State University

Saturday, November 13, 2010

Water could hold answer to graphene nanoelectronics

Researchers at Rensselaer Polytechnic Institute use water to open, tune graphene's band gap.

Troy, N.Y. – Researchers at Rensselaer Polytechnic Institute developed a new method for using water to tune the band gap of the nanomaterial graphene, opening the door to new graphene-based transistors and nanoelectronics.

By exposing a graphene film to humidity, Rensselaer Professor Nikhil Koratkar and his research team were able to create a band gap in graphene – a critical prerequisite to creating graphene transistors. At the heart of modern electronics, transistors are devices that can be switched "on" or "off" to alter an electrical signal. Computer microprocessors are comprised of millions of transistors made from the semiconducting material silicon, for which the industry is actively seeking a successor.

Graphene, an atom-thick sheet of carbon atoms arranged like a nanoscale chain-link fence, has no band gap. Koratkar's team demonstrated how to open a band gap in graphene based on the amount of water they adsorbed to one side of the material, precisely tuning the band gap to any value from 0 to 0.2 electron volts.

Graphene Nanoelectronics

Caption: Researchers at Rensselaer Polytechnic Institute developed a new method for using water to tune the band gap of the nanomaterial graphene, opening the door to new graphene-based transistors and nanoelectronics. In this optical micrograph image, a graphene film on a silicon dioxide substrate is being electrically tested using a four-point probe.

Credit: Rensselaer/Koratkar. Usage Restrictions: Please include image credit.
This effect was fully reversible and the band gap reduced back to zero under vacuum. The technique does not involve any complicated engineering or modification of the graphene, but requires an enclosure where humidity can be precisely controlled.

"Graphene is prized for its unique and attractive mechanical properties. But if you were to build a transistor using graphene, it simply wouldn't work as graphene acts like a semi-metal and has zero band gap," said Koratkar, a professor in the Department of Mechanical, Aerospace, and Nuclear Engineering at Rensselaer. "In this study, we demonstrated a relatively easy method for giving graphene a band gap.
This could open the door to using graphene for a new generation of transistors, diodes, nanoelectronics, nanophotonics, and other applications."

In its natural state, graphene has a peculiar structure but no band gap. It behaves as a metal and is known as a good conductor. This is compared to rubber or most plastics, which are insulators and do not conduct electricity. Insulators have a large band gap – an energy gap between the valence and conduction bands – which prevents electrons from conducting freely in the material.

Between the two are semiconductors, which can function as both a conductor and an insulator. Semiconductors have a narrow band gap, and application of an electric field can provoke electrons to jump across the gap. The ability to quickly switch between the two states – "on" and "off" – is why semiconductors are so valuable in microelectronics.

"At the heart of any semiconductor device is a material with a band gap," Koratkar said. "If you look at the chips and microprocessors in today's cell phones, mobile devices, and computers, each contains a multitude of transistors made from semiconductors with band gaps. Graphene is a zero band gap material, which limits its utility. So it is critical to develop methods to induce a band gap in graphene to make it a relevant semiconducting material."

The symmetry of graphene's lattice structure has been identified as a reason for the material's lack of band gap. Koratkar explored the idea of breaking this symmetry by binding molecules to only one side of the graphene. To do this, he fabricated graphene on a surface of silicon and silicon dioxide, and then exposed the graphene to an environmental chamber with controlled humidity. In the chamber, water molecules adsorbed to the exposed side of the graphene, but not on the side facing the silicon dioxide. With the symmetry broken, the band gap of graphene did, indeed, open up, Koratkar said. Also contributing to the effect is the moisture interacting with defects in the silicon dioxide substrate.

"Others have shown how to create a band gap in graphene by adsorbing different gasses to its surface, but this is the first time it has been done with water," he said. "The advantage of water adsorption, compared to gasses, is that it is inexpensive, nontoxic, and much easier to control in a chip application. For example, with advances in micro-packaging technologies it is relatively straightforward to construct a small enclosure around certain parts or the entirety of a computer chip in which it would be quite easy to control the level of humidity."

Based on the humidity level in the enclosure, chip makers could reversibly tune the band gap of graphene to any value from 0 to 0.2 electron volts, Korarkar said. ###

Along with Koratkar, authors on the paper are Theodorian Borca-Tasciuc, associate professor in the Department of Mechanical, Aerospace, and Nuclear Engineering at Rensselaer; Rensselaer mechanical engineering graduate student Fazel Yavari, who was first author on the paper; Rensselaer Focus Center New York Postdoctoral Research Associate Churamani Gaire; and undergraduate student Christo Kritzinger. Co-authors from Rice University are Professor Pulickel M. Ajayan; Postdoctoral Research Fellow Li Song; and graduate student Hemtej Gulapalli.

This study was supported by the Advanced Energy Consortium (AEC), National Institute of Standards and Technology (NIST) Nanoelectronics Research Initiative, and the U.S. Department of Energy Office of Basic Energy Sciences (BES).

Contact: Michael Mullaney mullam@rpi.edu 518-276-6161 Rensselaer Polytechnic Institute

Friday, November 12, 2010

Learning the World of Nanotechnology VIDEO

If nanotechnology is to take off in Oklahoma, the industry is going to need a new kind of worker; which is why a statewide effort is underway to peak students' interest at nanotechnology camps.

VIDEO and TEXT CREDIT: OklahomaHorizonTV

Light on silicon better than copper?

DURHAM, N.C. -- Step aside copper and make way for a better carrier of information -- light.

As good as the metal has been in zipping information from one circuit to another on silicon inside computers and other electronic devices, optical signals can carry much more, according to Duke University electrical engineers. So the engineers have designed and demonstrated microscopically small lasers integrated with thin film-light guides on silicon that could replace the copper in a host of electronic products.

The structures on silicon not only contain tiny light-emitting lasers, but connect these lasers to channels that accurately guide the light to its target, typically another nearby chip or component. This new approach could help engineers who, in their drive to create tinier and faster computers and devices, are studying light as the basis for the next generation information carrier.

The engineers believe they have solved some of the unanswered riddles facing scientists trying to create and control light at such a miniscule scale.

Nan Jokerst, Sabarni Palit, Duke University"Getting light onto silicon and controlling it is the first step toward chip scale optical systems," said Sabarni Palit, who this summer received her Ph.D. while working in the laboratory of Nan Marie Jokerst, J.A. Jones Distinguished Professor of Electrical and Computer Engineering at Duke's Pratt School of Engineering.
The results of team's experiments, which were supported by the Army Research Office, were published online in the journal Optics Letters.

"The challenge has been creating light on such a small scale on silicon, and ensuring that it is received by the next component without losing most of the light," Palit said.

"We came up with a way of creating a thin film integrated structure on silicon that not only contains a light source that can be kept cool, but can also accurately guide the wave onto its next connection," she said. "This integration of components is essential for any such chip-scale, light-based system."

The Duke team developed a method of taking the thick substrate off of a laser, and bonding this thin film laser to silicon. The lasers are about one one-hundreth of the thickness of a human hair. These lasers are connected to other structures by laying down a microscopic layer of polymer that covers one end of the laser and goes off in a channel to other components. Each layer of the laser and light channel is given its specific characteristics, or functions, through nano- and micro-fabrication processes and by selectively removing portions of the substrate with chemicals.

"In the process of producing light, lasers produce heat, which can cause the laser to degrade," Sabarni said. "We found that including a very thin band of metals between the laser and the silicon substrate dissipated the heat, keeping the laser functional."

For Jokerst, the ability to reliably facilitate individual chips or components that "talk" to each other using light is the next big challenge in the continuing process of packing more processing power into smaller and smaller chip-scale packages.

"To use light in chip-scale systems is exciting," she said. "But the amount of power needed to run these systems has to be very small to make them portable, and they should be inexpensive to produce. There are applications for this in consumer electronics, medical diagnostics and environmental sensing." ###

The work on this project was conducted in Duke's Shared Materials Instrumentation Facility, which, like similar facilities in the semiconductor industry, allows the fabrication of intricate materials in a totally "clean" setting. Jokerst is the facility's executive director.

Other members of the team were Duke's Mengyuan Huang, as well as Dr. Jeremy Kirch and professor Luke Mawst from the University of Wisconsin at Madision.

Contact: Richard Merritt richard.merritt@duke.edu 919-660-8414 Duke University

Thursday, November 11, 2010

Smaller is better in the viscous zone

DURHAM, N.C. -- Being the right size and existing in the limbo between a solid and a liquid state appear to be the secrets to improving the efficiency of chemical catalysts that can create better nanoparticles or more efficient energy sources.

When matter is in this transitional state, a catalyst can achieve its utmost potential with the right combination of catalyst particle size and temperature, according to a pair of Duke University researchers. A catalyst is an agent or chemical that facilitates a chemical reaction. It is estimated that more than 90 percent of chemical processes used by industry involve catalysts at some point.

This finding could have broad implications in almost every catalyst-based reaction, according to an engineer and a chemist at Duke who reported their findings on line in the American Chemical Society's journal ACS-NANO. The team found that the surface-to-volume ratio of the catalyst particle – its size -- is more important than generally appreciated.

"We found that the smaller size of a catalyst will lead to a faster reaction than if the bulk, or larger, version of the same catalyst is used," said Stefano Curtarolo, associate professor in the Department of Mechanical Engineering and Materials Sciences.


Caption: These are nanotubes. Credit: Jei Liu. Usage Restrictions: None.

Jie Liu, Duke University

Caption: This is Jie Liu of Duke University. Credit: Duke University Photography. Usage Restrictions: None.
"This is in addition to the usual excess of surface in the nanoparticles," said Curtarolo, who came up with the theoretical basis of the findings three years ago and saw them confirmed by a series of intricate experiments conducted by Jie Liu, Duke professor of chemistry.

"This opens up a whole new area of study, since the thermo-kinetic state of the catalyst has not before been considered an important factor," Curtarolo said. "It is on the face of it paradoxical. It's like saying if a car uses less gas (a smaller particle), it will go faster and further."

Their series of experiments were conducted using carbon nanotubes, and the scientists believe that same principles they described in the paper apply to all catalyst-driven processes.
Liu proved Curtarolo's hypothesis by developing a novel method for measuring not only the lengths of growing carbon nanotubes, but also their diameters. Nanotubes are microscopic "mesh-like" tubular structures that are used in hundreds of products, such as textiles, solar cells, transistors, pollution filters and body armor.

"Normally, nanotubes grow from a flat surface in an unorganized manner and look like a plate of spaghetti, so it is impossible to measure any individual tube," Liu said. "We were able to grow them in individual parallel strands, which permitted us to measure the rate of growth as well as the length of growth."

By growing these nanotubes using different catalyst particle sizes and at different temperatures, Liu was able to determine the "sweet spot" at which the nanotubes grew the fastest and longest. As it turned out, this happened when the particle was in its viscous state, and that smaller was better than larger, exactly as predicted before.

These measurements provided the experimental underpinning of Curtarolo's hypothesis that given a particular temperature, smaller nanoparticles are more effective and efficient per unit area than larger catalysts of the same type when they reside in that dimension between solid and liquid.

"Typically, in this field the experimental results come first, and the explanation comes later," Liu said. "In this case, which is unusual, we took the hypothesis and were able to develop a method to prove it correct in the laboratory." ###

The research was supported by the Office of Naval Research, the National Science Foundation, the Department of Energy and the National Council of Science and Technology (CONACYT), Mexico. Duke's Thomas McNicholas and Jay Simmons, as well as Felipe Cervantes-Sodi, Gabor Csanyi and Andrea Ferrari, University of Cambridge, U.K., were also members of the team.

Contact: Richard Merritt richard.merritt@duke.edu 919-660-8414 Duke University