Sunday, May 30, 2010

MU researchers show potential for new cancer detection and therapy method

University of Missouri School of Medicine scientists explain a potentially new early cancer detection and treatment method using nanoparticles created at MU in an article published in the Proceedings of the National Academy of Sciences. The article illustrates how engineered gold nanoparticles tied to a cancer-specific receptor could be targeted to tumor cells to treat prostate, breast or lung cancers in humans.

"When injected into the body, the Gastrin Releasing Peptide (GRP) cancer receptor serves as a signaling device to the gold nanoparticle, which allows for targeted delivery to the tumor site," said Kattesh Katti, PhD, who wrote the article with Raghuraman Kannan, PhD.

Gold Nanoparticles at MU

Caption: Raghuraman Kannan (left), and Kattesh Katti, faculty members in the department of radiology at the University of Missouri, have discovered gold nanoparticles that could be used to treat a variety of cancers.

Credit: University of Missouri. Usage Restrictions: None.
"Consequently, the radiotherapeutic properties of such nanoparticles also provides valuable imaging and therapeutic tools that can be used for early cancer detection and therapy in various human cancers."

Because GRP receptor mediated imaging and the radiotherapy specifically targets cancer cells, patients could benefit from a more effective treatment with fewer side effects. GRP receptors are abundant in prostate, breast and small lung cancer cells, and the effectiveness of Katti and Kannan's gold nanoparticles has been proved in numerous studies.
"The development of GRP-receptor specific gold nanoparticles and proof of cancer receptor specificity in living subjects, as described by Drs. Katti and Kannan, is a significant and critical step toward the utility of engineered gold nanoparticles in molecular imaging and therapy of various cancers," said Institute of Medicine member Sanjiv Sam Gambhir, MD, PhD, Virginia and D. K. Ludwig Professor, as well as director of the Molecular Imaging Program and Canary Center for Cancer Early Detection at Stanford University.

Katti, Kannan, and others with the MU School of Medicine Department of Radiology have been researching the development of tumor specific gold nanoparticles for more than five years.

"This discovery presents a plethora of realistic opportunities for clinical translation, not only in the development of nanomedicine-based diagnostic technologies for early stage detection but also for therapies for treating tumors in prostate, breast and small cell lung cancer," Kannan said.

Kannan and Katti have developed a library of more than 85 engineered nanoparticles for use in molecular imaging and therapy. With scientists at the MU Research Reactor (MURR), the most powerful university reactor in the world, they have developed cancer specific therapeutic radioactive gold nanoparticles. MURR is one of only a few sites worldwide able to produce cancer targeting gold nanoparticles. ###

In 2005, Katti received a prostate cancer research grant that distinguished MU as one of only 12 universities to participate in the National Cancer Institute's national nanotechnology platform partnership. The grant supported MU faculty members in radiology, MURR, veterinary medicine, chemistry, physics and other programs to collaborate in establishing MU as a leader in advancing nanomedicine for the early detection and treatment of cancer.

In addition to serving as director of MU's Cancer Nanotechnology Platform, Katti is a Curators' Distinguished Professor in Radiology and Physics and Margaret Proctor Mulligan Distinguished Professor in Medical Research. Kannan is the Michael J. and Sharon R. Bukstein Distinguished Faculty Scholar in Cancer Research.

The article, titled "Bombesin Functionalized Gold Nanoparticles Show In vitro and In vivo Cancer Receptor Specificity," is available online at: www.pnas.org/content/early/abstract

The Proceedings of the National Academy of Sciences of the United States of America is one of the world's most-cited multidisciplinary scientific serials. Since its establishment in 1914, it continues to publish cutting-edge research reports, commentaries, reviews, perspectives, colloquium papers, and actions of the academy.

Contact: Laura Gerding GerdingLA@health.missouri.edu 573-882-9193 University of Missouri-Columbia

Friday, May 28, 2010

UCLA engineer invents world's smallest, lightest telemedicine microscope

Portable, lensless device can deliver health care in resource-limited settings

Aydogan Ozcan, whose invention of a novel lensless imaging technology for use in telemedicine could radically transform global health care, has now taken his work a step further ― or tinier: The UCLA engineer has created a miniature microscope, the world's smallest and lightest for telemedicine applications.

The microscope, unveiled in a paper published online in the journal Lab on a Chip, builds on imaging technology known as LUCAS (Lensless Ultra-wide-field Cell Monitoring Array platform based on Shadow imaging), which was developed by Ozcan, an assistant professor of electrical engineering at the UCLA Henry Samueli School of Engineering and Applied Science and a researcher at UCLA's California NanoSystems Institute.

Ozcan's lensless microscope

Ozcan's microscope Prototype for Ozcan's lensless microscope

The prototype for the lensless microscope developed at UCLA has the approximate diameter of a US Quarter. The microscope only weighs 46 grams, about as much as a large egg. (Image Credit: Ozcan Research Group @ UCLA)
Instead of using a lens to magnify objects, LUCAS generates holographic images of microparticles or cells by employing a light-emitting diode to illuminate the objects and a digital sensor array to capture their images. The technology can be used to image blood samples or other fluids, even in Third World countries.

"This is a very capable and yet cost-effective microscope, shrunk into a very small package," Ozcan said. "Our goal with this project was to develop a device that can be used to improve health outcomes in resource-limited settings."

The lensless microscope, in addition to being far more compact and lightweight than conventional microscopes,
also obviates the need for a trained technicians to analyze the images produced ― images are analyzed by computer so that results are available instantaneously.

Weighing 46 grams ― approximately as much as a large egg ― the microscope is a self-contained imaging device. The only external attachments necessary are a USB connection to a smart-phone, PDA or computer, which supplies the microscope with power and allows images to be uploaded for conversion into results and then sent to a hospital. Samples are loaded using a small chip that can be filled with saliva or a blood smear for health monitoring. With blood smears, the lensless microscope is capable of accurately identifying cells and particles, including red blood cells, white blood cells and platelets. The technology has the potential to help monitor diseases like malaria, HIV and tuberculosis in areas where there are great distances between people in need of health care and the facilities capable of providing it, Ozcan said. It can even be used to test water quality in the field following a disaster like a hurricane or earthquake.

Using a couple of inexpensive add-on parts, the lensless microscope can also be converted into a differential interference contrast (DIC) microscope, also known as a Nomarski microscope. DIC microscopes are used to gain information on the density of a sample, giving the appearance of a 3-D image by putting lines and edges in stark contrast. The additional parts for conversion to a DIC microscope cost approximately $1 to $2.

A number of design elements lead Ozcan to believe his lensless microscope will be a useful medical tool in resource-limited settings, such as some countries in Africa. Two key requirements for such settings are ease of use and durability. The microscope requires minimal training; because of its large imaging field of view, the sample does not need to be scanned or perfectly aligned in the microscope. And operating the microscope is as simple as filling a chip with a sample and sliding the chip into a slot on the side of the microscope. Because of its large aperture, the lensless microscope is also resistant to problems caused by debris clogging the light source. In addition, there are few moving parts, making the microscope fairly robust.

The lensless microscope is also an example of a type of medicine known as telemedicine. In resource-limited settings, tools that are portable enough to do medical tests in the field are vital. Tools like the lensless microscope could be digitally integrated as part of a telemedicine network that connects various mobile health-care providers to a central lab or hospital, filling gaps in physical infrastructure with mobile tools. The transmission connections for such networks already exist in cellular networks, which have penetrated even the most remote corners of the globe.

"Making things user-friendly is what I love about being an engineer," Ozcan said. "It is very rewarding to create something that to the end-user is very simple, when in reality years of research and work went into the technology and product development."

The California NanoSystems Institute at UCLA is an integrated research center operating jointly at UCLA and UC Santa Barbara whose mission is to foster interdisciplinary collaborations for discoveries in nanosystems and nanotechnology; train the next generation of scientists, educators and technology leaders; and facilitate partnerships with industry, fueling 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 and an additional $250 million in federal research grants and industry funding. At the institute, scientists in the areas of biology, chemistry, biochemistry, physics, mathematics, computational science and engineering are measuring, modifying and manipulating the building blocks of our world — atoms and molecules. These scientists benefit from an integrated laboratory culture enabling them to conduct dynamic research at the nanoscale, leading to significant breakthroughs in the areas of health, energy, the environment and information technology.

For more news, visit the UCLA Newsroom and follow us on Twitter. ###

Contact: Jennifer Marcus jmarcus@cnsi.ucla.edu 310-267-4839 University of California - Los Angeles

Thursday, May 27, 2010

A little less force: Making atomic force microscopy work for cells

Atomic force microscopy, a tactile-based probe technique, provides a three-dimensional nanoscale image of a material by gliding a needle-like arm across the material's surface. The core of AFM imaging workhorse is a cantilever with a sharp tip that deflects as it encounters undulations across a surface. Due to a minimum force required for imaging, conventional AFM cantilevers can deform or even tear apart living cells and other biological materials. While scientists have made strides in reducing this minimum force by making smaller cantilevers, the force is still too great to image cells with high resolution. Indeed, for imaging objects smaller than the diffraction limit of light—that is, nanometer dimensions—this approach hits a roadblock as the instrument can no longer sense minute forces.

AFM Soft Matter Imaging

Caption: By placing a nanowire cantilever in the focus of a laser beam and detecting the resulting light pattern, scientists at the Molecular Foundry could use atomic force microscopy to non-destructively image the surface of a biological cell (green and blue structure) and the proteins (shown in brown) associated with it.

Credit: Illustration by Flavio Robles, Berkeley Lab Public Affairs. Usage Restrictions: None.

Babak Sanii and Paul Ashby

Caption: Babak Sanii (left) and Paul Ashby with Berkeley Lab's Molecular Foundry, have designed a nanowire-based imaging tool to study living cells and other soft materials in their natural, liquid environment.

Credit: Photo by Roy Kaltschmidt, Berkeley Lab Public Affairs. Usage Restrictions: None.
Now, however, scientists with the Molecular Foundry, a U.S. Department of Energy User Facility located at Berkeley Lab, have developed nano-sized cantilevers whose gentle touch could help discern the workings of living cells and other soft materials in their natural, liquid environment. Used in combination with a revolutionary detection mechanism, this new imaging tool is sensitive enough to investigate soft materials without the limitations present in other cantilevers.

"Whether we are considering biological systems or other complex, self-assembling nanostructures, this organization will be done in a liquid," says Paul Ashby, a Molecular Foundry staff scientist who led this research in the Foundry's Imaging and Manipulation of Nanostructures Facility. "If we have an investigative probe that excels in this environment, we could image individual proteins as they function on the cell surface."

Says Babak Sanii, a post-doctoral researcher in the Foundry, "Shrinking the cantilever down to nanoscale dimensions dramatically reduces the force it applies, but to monitor the movements of such a small cantilever, we needed a new detection scheme."

Rather than measuring the cantilever's deflection by bouncing a laser off it, Ashby and Sanii place the nanowire cantilever in the focus of a laser beam and detect the resulting light pattern, pinpointing the nanowire's position with high resolution. The duo say this work provides a launching pad for building a nanowire-based atomic force microscopes that could be used to study biological cells and model cellular components such as vesicles or bilayers. In particular, Ashby and Sanii hope to learn more about integrins, proteins found on the surface of cells that mediate adhesion and are part of signaling pathways linked to cell growth and migration.

"No present technique probes the assembly and dynamics of protein complexes in the cell membrane," adds Ashby. "A dynamic probe is the holy grail of soft matter imaging, and would help determine how protein complexes associate and disassociate."
"High sensitivity deflection detection of nanowires," by Babak Sanii and Paul D. Ashby, appears in Physical Review Letters and is available in Physical Review Letters online. ###

This work at the Molecular Foundry was supported by the DOE's Office of Science.

The Molecular Foundry is one 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. For more information about the DOE NSRCs, please visit nano.energy.gov.

Berkeley Lab is a U.S. Department of Energy national laboratory located in Berkeley, California. It conducts unclassified scientific research and is managed by the University of California. Visit our website at www.lbl.gov.

Contact: Aditi Risbud asrisbud@lbl.gov 510-486-4861 DOE/Lawrence Berkeley National Laboratory

Wednesday, May 26, 2010

Materials research advances reliability of faster smart sensors

In military and security situations, a split second can make the difference between life and death, so North Carolina State University’s development of new “smart sensors” that allow for faster response times from military applications is important. Equally important is new research from NC State that will help ensure those sensors will operate under extreme conditions – like those faced in Afghanistan or elsewhere.

“We’ve taken a sensor material called vanadium oxide and integrated it with a silicon chip,” says Dr. Jay Narayan, the John C. Fan Distinguished Chair Professor of Materials Science and Engineering at NC State and co-author of the research. “Normally sensors are hardwired to a computer. But now the sensor is part of the computer chip itself. The advantage is that now you have a smart sensor that can sense, manipulate and respond to information.”

smart sensors

New findings on how "smart sensors" function gives researchers the ability to improve their reliability.(Image courtesy of Alok Gupta and J. Narayan, NC State)
For example, such smart sensors allow for the development of infrared sensors that can respond more quickly in military or security applications.

The creation of these smart sensors is possible due to Narayan’s discovery of “domain matching epitaxy.” This model allows the creation of single, defect-free crystal layers of different materials – which amplify the transmission of electronic signals between those materials.
New findings presented by a team of NC State researchers (published in Applied Physics Letters and Journal of Applied Physics) now describe how vanadium oxide sensors work in conjunction with the silicon chips to which they are attached. Understanding how these sensors function gives researchers the ability to improve the reliability of these smart sensors, and account for variable conditions the sensors may be exposed to, such as various temperatures and pressures a sensor may face in Afghanistan or Iraq.

The research, which was funded by the National Science Foundation, was co-authored by Narayan, Dr. Roger Narayan, a professor of biomedical engineering at NC State, and NC State Ph.D. students Tsung Han Yang, Ravi Aggarwal, A. Gupta, and H. Zhou. The research was presented April 7 at the 2011 Materials Research Society Spring Meeting in San Francisco. The paper, titled “Mechanism of Semiconductor Metal Transition of Vanadium Oxide Thin Films,” won the First Prize in the MRS Symposium N: Functional Oxide Nanostructures and Heterostructures.

NC State’s Department of Materials Science and Engineering is part of the university’s College of Engineering. The Department of Biomedical Engineering is a joint department under both NC State’s College of Engineering and the University of North Carolina at Chapel Hill.

North Carolina State University from NC State News Services Technical Contact: Dr. Jay Narayan, 919.515.7874 Media Contact: Matt Shipman, News Services, 919.515.6386 matt_shipman@ncsu.edu

Advance made in thin-film solar cell technology

CORVALLIS, Ore. – Researchers have made an important breakthrough in the use of continuous flow microreactors to produce thin film absorbers for solar cells – an innovative technology that could significantly reduce the cost of solar energy devices and reduce material waste.

The advance was just reported in Current Applied Physics, a professional journal, by engineers from Oregon State University and Yeungnam University in Korea.

This is one of the first demonstrations that this type of technology, which is safer, faster and more economical than previous chemical solution approaches, could be used to continuously and rapidly deposit thin film absorbers for solar cells from such compounds as copper indium diselenide.

Chih-hung Chang
Chih-hung Chang, an associate professor of chemical engineering at Oregon State University, is developing new approaches to solar energy that may dramatically lower their cost while reducing waste and environmental impacts. (Photo courtesy of Oregon State University)
Previous approaches to use this compound – which is one of the leading photovoltaic alternatives to silicon-based solar energy devices – have depended on methods such as sputtering, evaporation, and electrodeposition. Those processes can be time-consuming, or require expensive vacuum systems or exotic chemicals that raise production costs.

Chemical bath deposition is a low-cost deposition technique that was developed more than a century ago. It is normally performed as a batch process, but changes in the growth solution over time make it difficult to control thickness. The depletion of reactants also limits the achievable thickness.
The technology invented at Oregon State University to deposit "nanostructure films" on various surfaces in a continuous flow microreactor, however, addresses some of these issues and makes the use of this process more commercially practical. A patent has been applied for on this approach, officials said.

"We've now demonstrated that this system can produce thin-film solar absorbers on a glass substrate in a short time, and that's quite significant," said Chih-hung Chang, an associate professor in the OSU School of Chemical, Biological and Environmental Engineering. "That's the first time this has been done with this new technique."

Further work is still needed on process control, testing of the finished solar cell, improving its efficiency to rival that of vacuum-based technology, and scaling up the process to a commercial application, Chang said.

Of some interest, researchers said, is that thin-film solar cells produced by applications such as this could ultimately be used in the creation of solar energy roofing systems. Conceptually, instead of adding solar panels on top of the roof of a residential or industrial building, the solar panel itself would become the roof, eliminating such traditional approaches as plywood and shingles.

"If we could produce roofing products that cost-effectively produced solar energy at the same time, that would be a game changer," Chang said. "Thin film solar cells are one way that might work. All solar applications are ultimately a function of efficiency, cost and environmental safety, and these products might offer all of that."

The research has been supported by the Process and Reaction Engineering Program of the National Science Foundation.

Related technology was also developed recently at OSU using nanostructure films as coatings for eyeglasses, which may cost less and work better than existing approaches. In that case, they would help capture more light, reduce glare and also reduce exposure to ultraviolet light. Scientists believe applications in cameras and other types of lenses are also possible.

More work such as this is expected to emerge from the new Oregon Process Innovation Center for Sustainable Solar Cell Manufacturing, a $2.7 million initiative based at OSU that will include the efforts of about 20 faculty from OSU, the University of Oregon, Portland State University and the Pacific Northwest National Laboratory.

Organizers of that initiative say they are aiming for "a revolution in solar cell processing and manufacturing" that might drop costs by as much as 50 percent while being more environmentally sensitive. In the process, they hope to create new jobs and industries in the Pacific Northwest. ###

Contact: Chih-hung Chang changch@che.orst.edu 541-737-8548 Oregon State University

Tuesday, May 25, 2010

Berkeley Lab scientists create 'molecular paper'

Two-dimensional, "sheet-like" nanostructures are commonly employed in biological systems such as cell membranes, and their unique properties have inspired interest in materials such as graphene. Now, Berkeley Lab scientists have made the largest two-dimensional polymer crystal self-assembled in water to date. This entirely new material mirrors the structural complexity of biological systems with the durable architecture needed for membranes or integration into functional devices.

These self-assembling sheets are made of peptoids, engineered polymers that can flex and fold like proteins while maintaining the robustness of manmade materials. Each sheet is just two molecules thick yet hundreds of square micrometers in area—akin to 'molecular paper' large enough to be visible to the naked eye.

Ron Zuckerman, Ki Tae Nam, DOE

Caption: Ron Zuckermann (left) and Ki Tae Nam with Berkeley Lab's Molecular Foundry, have developed a "molecular paper" material whose properties can be precisely tailored to control the flow of molecules, or serve as a platform for chemical and biological detection.

Credit: Photo by Roy Kaltschmidt, Berkeley Lab Public Affairs. Usage Restrictions: None.
What's more, unlike a typical polymer, each building block in a peptoid nanosheet is encoded with structural 'marching orders'—suggesting its properties can be precisely tailored to an application. For example, these nanosheets could be used to control the flow of molecules, or serve as a platform for chemical and biological detection.

"Our findings bridge the gap between natural biopolymers and their synthetic counterparts, which is a fundamental problem in nanoscience," said Ronald Zuckermann, Director of the Biological Nanostructures Facility at the Molecular Foundry. "We can now translate fundamental sequence information from proteins to a non-natural polymer, which results in a robust synthetic nanomaterial with an atomically-defined structure."
The building blocks for peptoid polymers are cheap, readily available and generate a high yield of product, providing a huge advantage over other synthesis techniques. Zuckermann, instrumental in developing the Foundry's one-of-a-kind robotic synthesis capabilities, worked with his team of coauthors to form libraries of peptoid materials. After screening many candidates, the team landed upon the unique combination of polymer building blocks that spontaneously formed peptoid nanosheets in water.

Zuckermann and coauthor Christian Kisielowski reached another first by using the TEAM 0.5 microscope at the National Center for Electron Microscopy (NCEM) to observe individual polymer chains within the peptoid material, confirming the precise ordering of these chains into sheets and their unprecedented stability while being bombarded with electrons during imaging.

"The design of nature-inspired, functional polymers that can be assembled into membranes of large lateral dimensions marks a new chapter for materials synthesis with direct impact on Berkeley Lab's strategically relevant initiatives such as the Helios project or Carbon Cycle 2.0," said NCEM's Kisielowski. "The scientific possibilities that come with this achievement challenge our imagination, and will also help move electron microscopy toward direct imaging of soft materials."

"This new material is a remarkable example of molecular biomimicry on many levels, and will no doubt lead to many applications in device fabrication, nanoscale synthesis and imaging," Zuckermann added. ###

This research is reported in a paper titled, "Free floating ultra-thin two-dimensional crystals from sequence-specific peptoid polymers," appearing in the journal Nature Materials and available in Nature Materials online. Co-authoring the paper with Zuckermann and Kisielowski were Ki Tae Nam, Sarah Shelby, Phillip Choi, Amanda Marciel, Ritchie Chen, Li Tan, Tammy Chu, Ryan Mesch, Byoung-Chul Lee and Michael Connolly.

This work at the Molecular Foundry was supported by DOE's Office of Science and the Defense Threat Reduction Agency.

The Molecular Foundry is one 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. For more information about the DOE NSRCs, please visit nano.energy.gov.

Berkeley Lab is a U.S. Department of Energy national laboratory located in Berkeley, California. It conducts unclassified scientific research and is managed by the University of California. Visit our website at www.lbl.gov.

Contact: Aditi Risbud asrisbud@lbl.gov 510-486-4861 DOE/Lawrence Berkeley National Laboratory

Sunday, May 23, 2010

New nano-tool synthesized at Scripps Research Institute

Two chemists at The Scripps Research Institute have synthesized a new nano-scale scientific tool — a tiny molecular switch that turns itself on or off as it detects metallic ions in its immediate surroundings.

Featured on the cover of the April 19, 2010 issue of the International Edition of the journal Angewandte Chemie, this molecule may be useful as a laboratory tool for controlling tiny reactions in the test tube, and it has potential to be developed as the basis of a new technology that could sensitively detect metals, toxins, and other pollutants in the air, water, or soil.

The molecule is named "ouroborand" after the mythical Ouroboros ("tail-eater" in Greek) — a lizard-like creature that swallows itself head-to-tail.

New Nano-Tool Synthesized at Scripps Research

In the Scripps Research laboratory where it was invented, the ouroborand molecule alternatively swallows or coughs out its tail—like a switch that goes on or off as it senses metals. (Illustrated by Fabien Durola of the Rebek lab; armadillo picture on the News&Views homepage courtesy of P. le F. N. Mouton.)
In mythology, the cyclic Ouroboros is always depicted with its tail in its mouth and this is usually taken as a symbol of eternity. In the Scripps Research laboratory where it was invented, the ouroborand molecule alternatively swallows or coughs out its tail—like a switch that goes on or off as it senses metals.

This switching is possible because the molecule has a cup-like head at one end and a tail at the other. The tail can curl around and plug the cup — just like the lizard swallowing its own tail.

"When no metals are present, the molecule's tail is held within its cavity at the other end," says Julius Rebek, who is the director of the Skaggs Institute for Chemical Biology at Scripps Research.

In the presence of zinc or other metal ions, the part of the molecule that links the head and the tail curls around the metal ions and pulls the head and the tail apart, springing the molecule open, says Rebek. Remove the metal, and the tail will move again to plug the other end of the molecule.

When Rebek and his postdoctoral fellow Fabien Durola synthesized the molecule and decided to name it ouroborand, they made a return of sorts to the dreams of chemists and alchemists long ago. In Medieval times and through the Renaissance, the mythical Ouroboros was a symbol used in alchemy, the ancient practice that was a forerunner to modern chemistry.

The spirit of this symbol later briefly carried over into modern chemistry as well. More than a century ago, the famous German chemist August Kekule had a dream about a serpent with its tail in its mouth, and this inspired him to propose the correct, circular structure of the compound benzene, a commonly used industrial solvent.

This month Rebek is presenting a lecture at the Kekule Institute at the University of Bonn in Germany, where he will formally unveil the new Ouroborand molecule — in all its tail-eating glory.
The Angewandte Chemie article, "The Ouroborand: A Cavitand with a Coordination-Driven Switching Device" is authored by Fabien Durola and Julius Rebek and is available online: DOI: 10.1002/anie.200906753, see www3.interscience.wiley.com/journal/123345195/abstract

This work was funded by the National Institutes of Health and the Skaggs Institute for Chemical Biology, and supported by a fellowship from the French Ministry of Foreign Affairs.

Contact: Keith McKeown kmckeown@scripps.edu 858-784-8134 Scripps Research Institute

Friday, May 21, 2010

Ultrasensitive imaging method uses gold-silver 'nanocages'

WEST LAFAYETTE, Ind. - New research findings suggest that an experimental ultrasensitive medical imaging technique that uses a pulsed laser and tiny metallic "nanocages" might enable both the early detection and treatment of disease.

The system works by shining near-infrared laser pulses through the skin to detect hollow nanocages and solid nanoparticles - made of an alloy of gold and silver - that are injected into the bloodstream.

Unlike previous approaches using tiny metallic nanorods and nanospheres, the new technique does not cause heat damage to tissue being imaged. Another advantage is that it does not produce a background "auto fluorescent" glow of surrounding tissues, which interferes with the imaging and reduces contrast and brightness, said Ji-Xin Cheng (pronounced Gee-Shin), an associate professor of biomedical engineering and chemistry at Purdue University.

Composite Image of Nanocages

Caption: New research findings suggest that an experimental ultrasensitive imaging technique that uses a pulsed laser and tiny metallic "nanocages" might enable both the early detection and treatment of disease. This composite image shows luminous nanocages, which appear like stars against a black background, and a living cell, at upper left. The gold-silver nanocages exhibit a bright "three-photon luminescence" when excited by the ultrafast pulsed laser, with 10-times greater intensity than pure gold or silver nanoparticles. The signal allows live cell imaging with negligible damage from heating.

Credit: Purdue University graphic/Ji-Xin Cheng. Usage Restrictions: None.
"This lack of background fluorescence makes the images much more clear and is very important for disease detection," he said. "It allows us to clearly identify the nanocages and the tissues."

The improved performance could make possible early detection and treatment of cancer. The tiny gold-silver cages also might be used to deliver time-released anticancer drugs to diseased tissue, said Younan Xia, the James M. McKelvey Professor for Advanced Materials in the Department of Biomedical Engineering at Washington University in St. Louis. His team fabricated the nanocages and nanoparticles used in the research.

The gold-silver structures yielded images 10 times brighter than other experimental imaging research using gold nanospheres and nanorods. The imaging technology provides brightness and contrast potentially hundreds of times better than conventional fluorescent dyes used for a wide range of biological imaging to study the inner workings of cells and molecules.

Findings were detailed in a research paper published online April 6 in the journal Angewandte Chemie's international edition. The paper was written by Purdue chemistry doctoral student Ling Tong, Washington University graduate student Claire M. Cobley and research assistant professor Jingyi Chen, Xia and Cheng.
The new imaging approach uses a phenomenon called "three-photon luminescence," which provides higher contrast and brighter images than conventional fluorescence imaging methods. Normally, three-photon luminescence is too dim to be used for imaging. However, the presence of gold and silver nanoparticles enhances the brightness, overcoming this obstacle. The ultrafast laser also is thought to possibly play a role by causing "third harmonic generation," which increases the brightness.

Previous research to develop the imaging system has required the use of "plasmons," or clouds of electrons moving in unison, to enhance brightness and contrast. However, using plasmons generates tissue-damaging heat. The new technique does not use plasmon enhancement, eliminating this heating, Cheng said.

The three-photon effect might enable scientists to develop advanced "non-linear optical techniques" that provide better contrast than conventional technologies.

"The three-photon imaging capability will potentially allow us to combine imaging and therapy for better diagnosis and monitoring," Xia said.

Researchers used a laser in the near-infrared range of the spectrum pulsing at the speed of femtoseconds, or quadrillionths of a second. The laser pulses 80 million times per second to illuminate tissues and organs after nanocages have been injected, Cheng said.

The cages and particles are about 40 nanometers wide, or roughly 100 times smaller than a red blood cell.

The researchers intravenously injected the nanocages into mice and then took images of the tiny structures in tissue samples from organs such as the liver and spleen. ###

The ongoing research is funded by the National Science Foundation and the National Institutes of Health. The research also is affiliated with the Birck Nanotechnology Center and the Bindley Bioscience Center, both in Purdue's Discovery Park.

Ji-Xin Cheng: engineering.purdue.edu/BME/Research/Labs/Cheng
Weldon School of Biomedical Engineering: www.purdue.edu/bme
Younan Xia: engineering.wustl.edu/facultybio

Abstract on the research in this release is available at: www.purdue.edu/newsroom/research/ChengNanocages

Contact: Emil Venere venere@purdue.edu 765-494-4709 Purdue University

Thursday, May 20, 2010

Study shows that size affects structure of hollow nanoparticles

A new study from North Carolina State University shows that size plays a key role in determining the structure of certain hollow nanoparticles. The researchers focused on nickel nanoparticles, which have interesting magnetic and catalytic properties that may have applications in fields as diverse as energy production and nanoelectronics.

"The principles we're uncovering here have great potential for nanofabrication – the creation of materials that have very small features, with many applications in fields ranging from electronics to medicine," says Dr. Joe Tracy, an assistant professor of materials science and engineering at NC State and co-author of the study.

Half-Oxidized Nanoparticle

Caption: This is a half-oxidized 26 nm nanoparticle. The Ni region is colored red, and the NiO is colored blue and green.

Credit: Dr. Joe Tracy, North Carolina State University. Usage Restrictions: Credit must be given.

Hollow Nickel Oxide Nanoparticles of Different Sizes

Caption: These are hollow or porous NiO nanoparticles of different sizes (6, 26, and 96 nm).

Credit: Dr. Joe Tracy, North Carolina State University. Usage Restrictions: Credit must be given.

Progress of the Cxidation Process

Caption: These images show 26 nm nanoparticles as the oxidation process progressed from 90-210 minutes at 300 °C.

Credit: Dr. Joe Tracy, North Carolina State University. Usage Restrictions: Credit must be given.
"This study improves our understanding of hollow nanoparticles and is a foundation for future work on applications in ultra-high density magnetic recording and more efficient catalysts, which is useful for chemical production, waste treatment and energy production."

At issue is the oxidation of nickel nanoparticles. If you start with a "core" piece of nickel and oxidize it, exposing it to oxygen at high temperatures, the structure of the material changes. If the material is partially oxidized – exposed to oxygen and high heat for a limited time – a solid nickel oxide shell forms around the material.

If the material is exposed to heat and oxygen for a longer period of time, further oxidation occurs. The external shell remains, but nickel is transported out of the core, leaving a void. If the material is fully oxidized, a larger void is created – leaving the nickel oxide shell effectively hollow. This conversion of solid to hollow nanoparticles is known as the "nanoscale Kirkendall Effect."

But what NC State researchers have found is that the size of the nickel core also plays a key role in the structure of these particles. For example, in smaller nickel nanoparticles – those with cores having diameters smaller than 30 nanometers (nm) – a single void is formed inside the shell during oxidation. This results in an asymmetric core of nickel, with a single void growing on one side of the core. The remaining core shrinks as the oxidation process continues. This is significant, in part, because the nickel oxide shell becomes progressively thicker on the side that abuts the core. The larger the core – within the 30 nm limit – the thicker that side of the shell becomes. In other words, you end up with a nickel oxide shell that can be significantly thicker on one side than the other.

However, the researchers found that larger nickel nanoparticles do something completely different. The researchers tested nanoparticles with nickel cores that were 96 nm in diameter, and found that the oxidation process in these nanoparticles created multiple voids in the core – though the core itself remained completely surrounded by the nickel oxide shell.
This process effectively resulted in the creation of bubbles throughout the core. The "skeletons" of those bubbles still remained, even after full oxidation, creating an essentially hollow shell that was still criss-crossed with some remnants of the nickel core.

"This tells us a lot about how to create nanoscale structures using the nanoscale Kirkendall Effect," Tracy says. "It's a building block for future research in the field." ###

The study, "Size-Dependent Nanoscale Kirkendall Effect During the Oxidation of Nickel Nanoparticles," is published in the journal ACS Nano. The research was funded by the National Science Foundation and NC State, and is co-authored by Tracy, NC State undergraduate Justin Railsback, NC State Ph.D. student Aaron Johnston-Peck and former NC State postdoctoral research associate Dr. Junwei Wang.

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

Wednesday, May 19, 2010

Cell phones that protect against deadly chemicals? Why not?

Crowdsourcing cell phones to detect chemicals. Do you carry a cell phone? Today, chances are it's called a "smartphone" and it came with a three-to-five megapixel lens built-in—not to mention an MP3 player, GPS or even a bar code scanner. This 'Swiss-Army-knife' trend represents the natural progression of technology—as chips become smaller/more advanced, cell phones absorb new functions.

What if, in the future, new functions on our cell phones could also protect us from toxic chemicals?

Homeland Security's Science and Technology Directorate (S&T)'s Cell-All is such an initiative.

Cell All

Caption: The sensor in the chip would identify the toxic chemical and send an alert to a central station and the cell phone carrier.

Credit: DHS S&T. Usage Restrictions: None.
Cell-All aims to equip cell phones with a sensor capable of detecting deadly chemicals. The technology is ingenious. A chip costing less than a dollar is embedded in a cell phone and programmed to either alert the cell phone carrier to the presence of toxic chemicals in the air, and/or a central station that can monitor how many alerts in an area are being received. One might be a false positive. Hundreds might indicate the need for evacuation.
"Our goal is to create a lightweight, cost-effective, power-efficient solution," says Stephen Dennis, Cell-All's program manager.

How would this wizardry work? Just as antivirus software bides its time in the background and springs to life when it spies suspicious activity, so Cell-All would regularly sniffs the surrounding air for certain volatile chemical compounds.

When a threat is sensed, an alert ensues in one of two ways. For personal safety issues such as a chlorine gas leak, a warning is sounded; the user can choose a vibration, noise, text message or phone call. For catastrophes such as a sarin gas attack, details—including time, location and the compound—are phoned home to an emergency operations center. While the first warning is beamed to individuals, the second warning works best with crowds. And that's where the genius of Cell-All lies—in crowd sourcing human safety.

Currently, if a person suspects that something is amiss, he might dial 9-1-1, though behavioral science tells us that it's easier to do nothing. And, as is often the case when someone phones in an emergency, the caller may be difficult to understand, diminishing the quality of information that's relayed to first responders. An even worse scenario: the person may not even be aware of the danger, like the South Carolina woman who last year drove into a colorless, odorless, and poisonous ammonia cloud.

In contrast, anywhere a chemical threat breaks out—a mall, a bus, subway or office—Cell-All will alert the authorities automatically. Detection, identification, and notification all take place in less than 60 seconds. Because the data are delivered digitally, Cell-All reduces the chance of human error. And by activating alerts from many people at once, Cell-All cleverly avoids the long-standing problem of false positives. The end result: emergency responders can get to the scene sooner and cover a larger area—essentially anywhere people are, casting a wider net than stationary sensors can.

And the privacy issue? Does this always-on surveillance mean that the government can track your precise whereabouts whenever it wants? To the contrary, Cell-All will operate only on an opt-in basis and will transmit data anonymously.

"Privacy is as important as technology," says Dennis. "After all, for Cell-All to succeed, people must be comfortable enough to turn it on in the first place."

For years, the idea of a handheld weapons of mass destruction detector has engaged engineers. In 2007, S&T called upon the private sector to develop concepts of operations. Today, thanks to increasingly successful prototype demonstrations, the Directorate is actively funding the next step in R&D—a proof of principle—to see if the concept is workable.

To this end, three teams from Qualcomm, the National Aeronautics and Space Administration (NASA), and Rhevision Technology are perfecting their specific area of expertise. Qualcomm engineers specialize in miniaturization and know how to shepherd a product to market. Scientists from the Center for Nanotechnology at NASA's Ames Research Center have experience with chemical sensing on low-powered platforms, such as the International Space Station. And technologists from Rhevision have developed an artificial nose—a piece of porous silicon that changes colors in the presence of certain molecules, which can be read spectrographically.

Similarly, S&T is pursuing what's known as cooperative research and development agreements with four cell phone manufacturers: Qualcomm, LG, Apple and Samsung. These written agreements, which bring together a private company and a government agency for a specific project, often accelerate the commercialization of technology developed for government purposes. As a result, Dennis hopes to have 40 prototypes in about a year, the first of which will sniff out carbon monoxide and fire.

To be sure, Cell-All's commercialization may take several years. Yet the goal seems eminently achievable: Just as Gates once envisioned a computer on every desk in every home, so Dennis envisions a chemical sensor in every cell phone in every pocket, purse or belt holster.

And if it's not already the case, says Dennis, "Our smartphones may soon be smarter than we are." ###

Contact: John Verrico john.verrico@dhs.gov 202-254-2385 US Department of Homeland Security - Science and Technology

Monday, May 17, 2010

Significant findings about protein architecture may aid in drug design, generation of nanomaterials

Researchers in Singapore report major step forward in effort to understand and engineer protein structure.

Researchers in Singapore are reporting this week that they have gleaned key insights into the architecture of a protein that controls iron levels in almost all organisms. Their study culminated in one of the first successful attempts to take apart a complex biological nanostructure and isolate the rules that govern its natural formation.

The Nanyang Technological University team's work on the protein ferritin, the results of which appear in this week's issue of the Journal of Biological Chemistry, is expected to have significant ramifications on the fields of drug design and nanomaterials.

Yu Zhang, Nanyang Technological University

Caption: Yu Zhang is a doctoral student at Nanyang Technological University.

Credit: handout. Usage Restrictions: None.
"Engineering the structure of a protein is one of the ultimate dreams of structural biologists," wrote one of the journal's peer reviewers, "and approaching that dream is greatly enabled through studies aimed at finding out what governs the nanoarchitecture of the protein."

Brendan P. Orner, the assistant professor who oversaw the team's work, described the protein ferritin as a potential model for explaining complicated protein structure in general.

Across the biological kingdoms, ferritin regulates the distribution of iron, which is necessary for a number of cellular functions but also forms reactive ions that can be lethal to cells. Shaped like a spherical nanocage, ferritin is made up of 24 proteins, and it sequesters the reactive iron ions in its hollow interior. In humans, ferritin prevents iron deficiency and overload.
"The rules that govern self-assembling nanosystems, like the ferritin model, are poorly understood," Orner explained. "We systematically analyzed the interactions between the 24 ferritin units that make up the nanocage and identified the hot spots that are crucial to the cage's formation."

Their goal was to discover which amino acids are responsible for assembling the cage, and they found that it is possible to both disassemble ferritin by removing single side chains of amino acids and, surprisingly, to stabilize the structure by removing other side chains.

Understanding the assembly of the nanocage could open the door to drug design that will disrupt the structure and function of defective proteins that cause or contribute to disease. It also may aid in the creation of biological nanostructures in which scientists can grow special particles and materials with a variety of properties and applications.

"Cell biology provides many structures that are on the nanoscale and have amazing complexity and symmetry," Orner said. "The problem is that many of these structures are, like ferritin, self-assembled proteins, and, if we are going to use them for nanomaterials applications, we need to understand the fundamentals that make them form this way naturally."

Orner and his team members are particularly interested in growing nanoparticles of precise dimensions inside ferritin shells. Already, they have developed a new method to grow gold nanoparticles in them.

"Slight deviations in size or shape can radically change nanoparticles' properties, particularly in the case of metals and semiconductors," Orner said. "Our ferritin proteins are hollow, so, when we grow mineral or metal clusters inside them, the growth stops when the nanoparticles reach the limits of the protein shell."

By studying the rules that control the folding and assembly of such a protein in nature, Orner said, the investigators hope to be able to manipulate them one day to create new proteins with novel sizes and shapes and, therefore, generate nanoparticles of novel sizes and shapes inside them.

"Those nanoparticles could be used for in-vitro assays to do high-throughput drug screening of some protein-protein interactions involved in virus infection and cancer, for example," he said.

Orner's team included doctoral students Yu Zhang and Rongli Fan, undergraduate students Siti Raudah, Huihian Teo and Gwenda Teo, and scholar Xioming Sun. Their research was funded by the Singapore Ministry of Education and Nanyang Technological University.

Their resulting article has been named a "Paper of the Week" by the Journal of Biological Chemistry, putting it in the top 1 percent of papers reviewed by the editorial board in terms of significance and overall importance. ###

About the American Society for Biochemistry and Molecular Biology

The ASBMB is a nonprofit scientific and educational organization with more than 12,000 members worldwide. Most members teach and conduct research at colleges and universities. Others conduct research in various government laboratories, at nonprofit research institutions and in industry. The Society's student members attend undergraduate or graduate institutions. For more information about ASBMB, visit www.asbmb.org.

Contact: Angela Hopp ahopp@asbmb.org 301-634-7389 American Society for Biochemistry and Molecular Biology

Sunday, May 16, 2010

Closing in on a carbon-based solar cell

BLOOMINGTON, Ind. -- To make large sheets of carbon available for light collection, Indiana University Bloomington chemists have devised an unusual solution -- attach what amounts to a 3-D bramble patch to each side of the carbon sheet. Using that method, the scientists say they were able to dissolve sheets containing as many as 168 carbon atoms, a first.

The scientists' report, online, will appear in an issue of Nano Letters, an American Chemical Society journal.

"Our interest stems from wanting to find an alternative, readily available material that can efficiently absorb sunlight," said chemist Liang-shi Li, who led the research. "At the moment the most common materials for absorbing light in solar cells are silicon and compounds containing ruthenium. Each has disadvantages."

Graphene Sensitizer, Skeletal Model

Caption: This is a 2-D view of a graphene sheet (black) and attached sidegroups (blue) that IU Bloomington chemist Liang-shi Li and his collaborators devised. In reality, each sidegroup rotates 90 degrees or so out of graphene's plane. The three blue, tail-like hydrocarbons of each sidegroup have great freedom of movement, but two are likely to hover over the graphene, making it very unlikely that one graphene sheet will touch another.

Credit: Image by Liang-shi Li. Usage Restrictions: None.

Graphene Sensitizers, Space-filling Models

Caption: Two graphene molecules (dark grey) are caged by sidegroups (blue) attached to each graphene sheet. The sidegroups help prevent the graphene sheets from stacking, as they are prone to do.

Credit: Image by Liang-shi Li. Usage Restrictions: None.
Their main disadvantage is cost and long-term availability. Ruthenium-based solar cells can potentially be cheaper than silicon-based ones, but ruthenium is a rare metal on Earth, as rare as platinum, and will run out quickly when the demand increases.

Carbon is cheap and abundant, and in the form of graphene, capable of absorbing a wide range of light frequencies. Graphene is essentially the same stuff as graphite (pencil lead), except graphene is a single sheet of carbon, one atom thick. Graphene shows promise as an effective, cheap-to-produce, and less toxic alternative to other materials currently used in solar cells. But it has also vexed scientists.

For a sheet of graphene to be of any use in collecting photons of light, the sheet must be big. To use the absorbed solar energy for electricity, however, the sheet can't be too big. Unfortunately, scientists find large sheets of graphene difficult to work with, and their sizes even harder to control. The bigger the graphene sheet, the stickier it is, making it more likely to attract and glom onto other graphene sheets. Multiple layers of graphene may be good for taking notes, but they also prevent electricity.

Chemists and engineers experimenting with graphene have come up with a whole host of strategies for keeping single graphene sheets separate. The most effective solution prior to the Nano Letters paper has been breaking up graphite (top-down) into sheets and wrap polymers around them to make them isolated from one another. But this makes graphene sheets with random sizes that are too large for light absorption for solar cells.

Li and his collaborators tried a different idea. By attaching a semi-rigid, semi-flexible, three-dimensional sidegroup to the sides of the graphene, they were able to keep graphene sheets as big as 168 carbon atoms from adhering to one another. With this method, they could make the graphene sheets from smaller molecules (bottom-up) so that they are uniform in size. To the scientists' knowledge, it is the biggest stable graphene sheet ever made with the bottom-up approach.
The sidegroup consists of a hexagonal carbon ring and three long, barbed tails made of carbon and hydrogen. Because the graphene sheet is rigid, the sidegroup ring is forced to rotate about 90 degrees relative to the plane of the graphene. The three brambly tails are free to whip about, but two of them will tend to enclose the graphene sheet to which they are attached.

The tails don't merely act as a cage, however. They also serve as a handle for the organic solvent so that the entire structure can be dissolved. Li and his colleagues were able to dissolve 30 mg of the species per 30 mL of solvent.

"In this paper, we found a new way to make graphene soluble," Li said. "This is just as important as the relatively large size of the graphene itself."

To test the effectiveness of their graphene light acceptor, the scientists constructed rudimentary solar cells using titanium dioxide as an electron acceptor. The scientists were able to achieve a 200-microampere-per-square-cm current density and an open-circuit voltage of 0.48 volts. The graphene sheets absorbed a significant amount of light in the visible to near-infrared range (200 to 900 nm or so) with peak absorption occurring at 591 nm.

The scientists are in the process of redesigning the graphene sheets with sticky ends that bind to titanium dioxide, which will improve the efficiency of the solar cells.

"Harvesting energy from the sun is a prerequisite step," Li said. "How to turn the energy into electricity is the next. We think we have a good start." ###

PhD students Xin Yan and Xiao Cui and postdoctoral fellow Binsong Li also contributed to this research. It was funded by grants from the National Science Foundation and the American Chemical Society Petroleum Research Fund.

To speak with Liang-shi Li, please contact David Bricker, University Communciations, at 812-856-9035 or brickerd@indiana.edu.

"Large, Solution-Processable Graphene Quantum Dots as Light Absorbers for Photovoltaics," Nano Letters (Articles ASAP)

Contact: David Bricker brickerd@indiana.edu 812-856-9035 Indiana University

Friday, May 14, 2010

Graphene films clear major fabrication hurdle

Graphene, the two-dimensional crystalline form of carbon, is a potential superstar for the electronics industry. With freakishly mobile electrons that can blaze through the material at nearly the speed of light – 100 times faster than electrons can move through silicon – graphene could be used to make superfast transistors or computer memory chips. Graphene's unique "chicken wire" atomic structure exhibits incredible flexibility and mechanical strength, as well as unusual optical properties that could open a number of promising doors in both the electronics and the photonics industries. However, among the hurdles preventing graphite from joining the pantheon of star high-tech materials, perhaps none looms larger than just learning to make the stuff in high quality and usable quantities.

CVD Graphene on Copper

Caption: Panel (a): Optical image of a CVD graphene film on a 450 nanometer copper shows the finger morphology of the metal; (b) Raman 2D band map of the graphene film between the metal fingers, over the area marked by the red square on left.

Credit: Image from Yuegang Zhang. Usage Restrictions: None.

CVD Graphene on Copper Graphic

Caption: To make a graphene thin film, Berkeley researchers (a) evaporated a thin layer of copper on a dielectric surface; (b) then used CVD to lay down a graphene film over the copper. (c) The copper dewets and evaporates leaving (d) a graphene film directly on a dielectric substrate.

Credit: Image from Yuegang Zhang. Usage Restrictions: None.
"Before we can fully utilize the superior electronic properties of graphene in devices, we must first develop a method of forming uniform single-layer graphene films on nonconducting substrates on a large scale," says Yuegang Zhang, a materials scientist with the Lawrence Berkeley National Laboratory (Berkeley Lab). Current fabrication methods based on mechanical cleavage or ultrahigh vacuum annealing, he says, are ill-suited for commercial-scale production. Graphene films made via solution-based deposition and chemical reduction have suffered from poor or uneven quality.

Zhang and colleagues at Berkeley Lab's Molecular Foundry, a U.S. Department of Energy (DOE) center for nanoscience, have taken a significant step at clearing this major hurdle. They have successfully used direct chemical vapor deposition (CVD) to synthesize single-layer films of graphene on a dielectric substrate. Zhang and his colleagues made their graphene films by catalytically decomposing hydrocarbon precursors over thin films of copper that had been pre-deposited on the dielectric substrate.
The copper films subsequently dewetted (separated into puddles or droplets) and were evaporated. The final product was a single-layer graphene film on a bare dielectric.

"This is exciting news for electronic applications because chemical vapor deposition is a technique already widely used in the semiconductor industry," Zhang says. "Also, we can learn more about the growth of graphene on metal catalyst surfaces by observing the evolution of the films after the evaporation of the copper. This should lay an important foundation for further control of the process and enable us to tailor the properties of these films or produce desired morphologies, such as graphene nanoribbons."

Zhang and his colleagues have reported their findings in the journal Nano Letters in a paper titled, "Direct Chemical Vapor Deposition of Graphene on Dielectric Surfaces." Other co-authors of this paper were Ariel Ismach, Clara Druzgalski, Samuel Penwell, Maxwell Zheng, Ali Javey and Jeffrey Bokor, all with Berkeley Lab.

In their study, Zhang and his colleagues used electron-beam evaporation to deposit copper films ranging in thickness from 100 to 450 nanometers. Copper was chosen because as a low carbon solubility metal catalyst it was expected to allow better control over the number of graphene layers produced. Several different dielectric substrates were evaluated including single-crystal quartz, sapphire, fused silica and silicon oxide wafers. CVD of the graphene was carried out at 1,000 degrees Celsius in durations that ranged from 15 minutes up to seven hours.

"This was done to allow us to study the effect of film thickness, substrate type and CVD growth time on the graphene formation," Zhang says.

A combination of scanning Raman mapping and spectroscopy, plus scanning electron and atomic force microscopy confirmed the presence of continuous single-layer graphene films coating metal-free areas of dielectric substrate measuring tens of square micrometers.

"Further improvement on the control of the dewetting and evaporation process could lead to the direct deposition of patterned graphene for large-scale electronic device fabrication, Zhang says. "This method could also be generalized and used to deposit other two-dimensional materials, such as boron-nitride."

Even the appearance of wrinkles in the graphene films that followed along the lines of the dewetting shape of the copper could prove to be beneficial in the long-run. Although previous studies have indicated that wrinkles in a graphene film have a negative impact on electronic properties by introducing strains that reduce electron mobility, Zhang believes the wrinkles can be turned to an advantage.

"If we can learn to control the formation of wrinkles in our films, we should be able to modulate the resulting strain and thereby tailor electronic properties," he says. "Further study of the wrinkle formation could also give us important new clues for the formation of graphene nanoribbons." ###

This work was primarily supported by the DOE Office of Science.

The Molecular Foundry is one 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.

Berkeley Lab is a U.S. Department of Energy national laboratory located in Berkeley, California. It conducts unclassified scientific research and is managed by the University of California. Visit our website at www.lbl.gov.

Contact: Lynn Yarris lcyarris@lbl.gov 510-486-5375 DOE/Lawrence Berkeley National Laboratory

Thursday, May 13, 2010

Researchers use novel nanoparticle vaccine to cure type 1 diabetes in mice

NEW YORK, -- Using a sophisticated nanotechnology-based "vaccine," researchers were able to successfully cure mice with type 1 diabetes and slow the onset of the disease in mice at risk for the disease. The study, co-funded by the Juvenile Diabetes Research Foundation, provides new and important insights into understanding how to stop the immune attack that causes type 1 diabetes, and could even have implications for other autoimmune diseases.

The study, conducted at the University of Calgary in Alberta, Canada, was published today in the online edition of the scientific journal Immunity.

The research was led by Dr. Pere Santamaria from the Julia McFarlane Diabetes Researchers Center at the University of Calgary, Alberta.

Dr. Pere Santamaria

Dr. Pere Santamaria 2008 University of Calgary - Faculty of Medicine. All rights reserved.
The researchers were looking to specifically stop the autoimmune response that causes type 1 diabetes without damaging the immune cells that provide protection against infections – what is called an "antigen-specific" immunotherapy. Type 1 diabetes is caused when certain white blood cells (called T cells) mistakenly attack and destroy the insulin-producing beta cells in the pancreas.

Antigen-specific immunotherapies, like Dr. Santamaria's work on nanovaccines, are a priority within JDRF's Immune Therapies program.

"Essentially there is an internal tug-of-war between aggressive T-cells that want to cause the disease and weaker T cells that want to stop it from occurring," said Dr. Santamaria, who is a JDRF Scholar – a research award to academic scientists taking innovative and creative approaches to better treating and curing type 1 diabetes and its complications.
The researchers developed a unique vaccine comprised of nanoparticles, which are thousands of times smaller than the size of a cell. These nanoparticles are coated with protein fragments – peptides – specific to type 1 diabetes that are bound to molecules (MHC molecules) that play a critical role in presenting peptides to T cells. The nanoparticle vaccine worked by expanding the number of peptide-specific regulatory T cells that suppressed the aggressive immune attack that destroys beta cells. The expanded peptide-specific regulatory cells shut down the autoimmune attack by preventing aggressive autoimmune cells from being stimulated by either the peptide contained in the vaccine or by any other type 1 diabetes autoantigen presented simultaneously on the same antigen presenting cell.

The research also provided an important insight into the ability to translate these findings in mice into therapeutics for people with diabetes: nanoparticles that contained human diabetes-related molecules were able to restore normal blood sugar levels in a humanized mouse model of diabetes.

According to Teodora Staeva, Ph.D., JDRF Program Director of Immune Therapies, a key finding from the Alberta study is that only the immune cells specifically focused on aggressively destroying beta cells (or, alternatively, regulating these cells) responded to the antigen-specific nanoparticle vaccine. That means the treatment did not compromise the rest of the immune system – a key consideration for the treatment to be safe and effective in an otherwise healthy person with type 1 diabetes. "The potential that nanoparticle vaccine therapy holds in reversing the immune attack without generally suppressing the immune system is significant," said Dr. Staeva. "Dr. Santamaria's research has provided both insight into pathways for developing new immunotherapies and proof-of-concept of a specific therapy that exploits these pathways for preventing and reversing type 1 diabetes."

Dr. Santamaria noted that the study had implications for other autoimmune diseases beyond type 1 diabetes. "If the paradigm on which this nanovaccine is based holds true in other chronic autoimmune diseases, such as multiple sclerosis, rheumatoid arthritis, and others, nanovaccines might find general applicability in autoimmunity," he said.

The nanoparticle vaccine technology used in the study has been licensed by Parvus Therapeutics, Inc., a biotechnology company arising from the University Technology International LP, the technology transfer and commercialization center for the University of Calgary. Parvus Therapeutics is focused on the development and commercialization of the nanotechnology-based therapeutic platform for the potential treatment of type 1 diabetes. ###

About JDRF

JDRF is a leader in setting the agenda for diabetes research worldwide, and is the largest charitable funder and advocate of type 1 research. The mission of JDRF is to find a cure for diabetes and its complications through the support of research. Type 1 diabetes is a disease which strikes children and adults suddenly and requires multiple injections of insulin daily or a continuous infusion of insulin through a pump. Insulin, however, is not a cure for diabetes, nor does it prevent its eventual and devastating complications which may include kidney failure, blindness, heart disease, stroke, and amputation.

Since its founding in 1970 by parents of children with type 1 diabetes, JDRF has awarded more than $1.4 billion to diabetes research, including more than $100 million in FY2009.

Wednesday, May 12, 2010

Wake Forest earns patent for efficient, inexpensive fiber-based solar cells

Wake Forest University has received the first patent for a new solar cell technology that can double the energy production of today’s flat cells at a fraction of the cost.

“It comes at a pretty high price to be green,” said David Carroll, Ph.D., the director of Wake Forest’s Center for Nanotechnology and Molecular Materials, where the fiber cell was developed. “This device can make a huge difference.”

The university received the patent for fiber-based photovoltaic, or solar, cells from the European Patent Office; applications to the U.S. Patent Office are pending. The patent on the technology has been licensed to FiberCell Inc., based in the Piedmont Triad Research Park of Winston-Salem, to develop a way to manufacture the cells. The company is producing its first large test cells.

David Carroll

David Carroll, associate professor of physics at Wake Forest University in Winston-Salem, N.C. is director of the school's Center for Nanotechnology and Molecular Materials, where recent research breakthroughs led to the formation of two start-up companies, FiberCell and PlexiLight, to commercialize new nanotechnologies.
These new solar cells are made from millions of miniscule plastic fibers that can collect sunlight at oblique angles – even when the sun is rising and setting. Flat-cell technology captures light primarily when the sun is directly above.

Where a flat cell loses energy when the sun’s rays bounce off its shiny surface, the fiber-based design creates more surface area to confine the sun’s rays, trapping the light in the tiny fiber “cans” where it bounces around until it is absorbed almost completely. That means much greater energy production with fiber-based cells: Wake Forest’s fiber cells could produce about twice as many kilowatt hours per day as standard flat cells.
“We’ve been able to show that with a standard absorber we can collect more of the photons than anyone else can,” Carroll said. “Because of the way the device works, I get more power.”

To make the cells, the plastic fibers are assembled onto plastic sheets, with a technology similar to that used to create the tops of soft-drink cups. The absorber – either a polymer or a dye – is sprayed on. The plastic makes the cells lightweight and flexible – a manufacturer could roll them up and ship them anywhere cheaply.

Carroll envisions several key uses for fiber cells:

* Green building: “We’ve known how to build the ‘smart house,’ it’s just been too expensive,” he said. “The fiber cell can change that.” Alter the dimensions and dye color, and builders can integrate the cells nearly anywhere in the home’s design. Because fiber cells can collect light at various angles, they no longer have to stay on the roof to work. Partner the cells with devices that could store the power more efficiently, turn off lights and appliances when not in use, and capture and redirect the heat the building radiates at night, and you have a more affordable, energy-efficient structure.

* Bringing power to developing countries: Once the primary manufacturer ships the lightweight, plastic fiber cells, satellite plants in poor countries can spray them with the dye and prepare them for installation. Carroll estimates it would cost about $5 million to set up a finishing plant – about $15 million less than it could cost to set up a similar plant for flat cells.

* Revolutionizing the power grid: “What if you didn’t own your roof,” Carroll asked. “What if the power company did?” The fiber cells installed on some homes in each neighborhood would feed the grid, and the power company would monitor energy collection and distribution through a computer network. The homeowner would not maintain the cells; that responsibility would fall to the power company.

Wake Forest University’s Center for Nanotechnology and Molecular Materials uses revolutionary science to address the pressing needs of human society, from health care to green technologies. It is a shared resource serving academic, industrial and governmental researchers across the region.

Press Contacts: Cheryl Walker (336) 758-5237 walkercv@wfu.edu Ellen Sterner Sedeno
(214) 546-8893 sternersedeno@sbcglobal.net

Tuesday, May 11, 2010

Brown University scientists discover new principle in material science

PROVIDENCE, R.I. [Brown University] — Materials scientists have known that a metal's strength (or weakness) is governed by dislocation interactions, a messy exchange of intersecting fault lines that move or ripple within metallic crystals. But what happens when metals are engineered at the nanoscale? Is there a way to make metals stronger and more ductile by manipulating their nanostructures?

Brown University scientists may have figured out a way. In a paper published in Nature, Huajian Gao and researchers from the University of Alabama and China report a new mechanism that governs the peak strength of nanostructured metals. By performing 3-D atomic simulations of divided grains of nanostructured metals, Gao and his team observed that dislocations organize themselves in highly ordered, necklace-like patterns throughout the material. The nucleation of this dislocation pattern is what determines the peak strength of materials, the researchers report.

Atomic Strength

Caption: A material science team led by Brown University engineers has found that the deformation of nanotwinned metals is characterized by the motion of highly ordered, necklace-like patterns of crystal defects called dislocations.

Credit: Huajian Gao and Xiaoyan Li, Brown University. Usage Restrictions: None.

Huajian Gao and Xiaoyan Li, Brown University

Caption: Pictured are Brown University engineering professor Huajian Gao, right, and engineering graduate student Xiaoyan Li.

Credit: Lauren Brennan, Brown University. Usage Restrictions: None.
The finding could open the door to producing stronger, more ductile metals, said Gao, professor of engineering at Brown. "This is a new theory governing strength in materials science," he added. "Its significance is that it reveals a new mechanism of material strength that is unique for nanostructured materials."

Divide a grain of metal using a specialized technique, and the pieces may reveal boundaries within the grain that scientists refer to as twin boundaries. These are generally flat, crystal surfaces that mirror the crystal orientations across them. The Chinese authors created nanotwinned boundaries in copper and were analyzing the space between the boundaries when they made an interesting observation: The copper got stronger as the space between the boundaries decreased from 100 nanometers, ultimately reaching a peak of strength at 15 nanometers. However, as the spacing decreased from 15 nanometers, the metal got weaker.

"This is very puzzling," Gao said.

So Gao and Brown graduate student Xiaoyan Li dug a little further. The Brown scientists reproduced their collaborators' experiment in computer simulations involving 140 million atoms. They used a supercomputer at the National Institute for Computational Sciences in Tennessee, which allowed them to analyze the twin boundaries at the atomic scale. To their surprise, they saw an entirely new phenomenon: A highly ordered dislocation pattern controlled by nucleation had taken hold and dictated the copper's strength. The pattern was characterized by groups of atoms near the dislocation core and assembled in highly ordered, necklace-like patterns.

"They're not getting in each other's way. They're very organized," Gao said.

From the experiments and the computer modeling, the researchers theorize that at the nanoscale, dislocation nucleation can become the governing principle to determining a metal's strength or weakness. The authors presented a new equation in the Nature paper to describe the principle.

"Our work provides a concrete example of a source-controlled deformation mechanism in nanostructured materials for the first time and, as such, can be expected to have a profound impact on the field of materials science," Gao said. ###

The other researchers who contributed to the paper are Yujie Wei from the University of Alabama and Ke Lu and Lei Lu from the Chinese Academy of Sciences. The U.S. National Science Foundation, the National Science Foundation in China and the Ministry of Science and Technology in China funded the research.
Contact: Richard Lewis Richard_Lewis@brown.edu 401-863-3766 Brown University

Monday, May 10, 2010

Cold atoms and nanotubes come together in an atomic 'black hole'

Atoms spiral toward a charged carbon nanotube under dramatic acceleration before splitting apart.

CAMBRIDGE, Mass., -- Carbon nanotubes, long touted for applications in materials and electronics, may also be the stuff of atomic-scale black holes.

Physicists at Harvard University have found that a high-voltage nanotube can cause cold atoms to spiral inward under dramatic acceleration before disintegrating violently. Their experiments, the first to demonstrate something akin to a black hole at atomic scale, are described in the current issue of the journal Physical Review Letters.

Single-Wall Carbon Nanotube

Caption: Launched laser-cooled atoms are captured by a single, suspended, single-wall carbon nanotube charged to hundreds of volts. A captured atom spirals towards the nanotube (white path) and reaches the environs of the tube surface, where its valence electron (yellow) tunnels into the tube. The resulting ion (purple) is ejected and detected, and the dynamics at the nanoscale are sensitively probed.

Credit: Anne Goodsell and Tommi Hakala/Harvard University. Usage Restrictions: None.
"On a scale of nanometers, we create an inexorable and destructive pull similar to what black holes exert on matter at cosmic scales," says Lene Vestergaard Hau, Mallinckrodt Professor of Physics and of Applied Physics at Harvard. "As importantly for scientists, this is the first merging of cold-atom and nanoscale science, and it opens the door to a new generation of cold atom experiments and nanoscale devices."

Hau and co-authors Anne Goodsell, Trygve Ristroph, and Jene A. Golovchenko laser-cooled clouds of one million rubidium atoms to just a fraction of a degree above absolute zero. The physicists then launched this millimeter-long atomic cloud towards a suspended carbon nanotube, located some two centimeters away and charged to hundreds of volts.

The vast majority of the atoms passed right by the wire, but those that came within a micron of it -- roughly 10 atoms in every million-atom cloud -- were inescapably attracted, reaching high speeds as they spiraled toward the nanotube.
"From a start at about 5 meters per second, the cold atoms reach speeds of roughly 1,200 meters per second, or more than 2,700 miles per hour, as they circle the nanotube," says Goodsell, a graduate student on the project and now a postdoctoral researcher in physics at Harvard. "As part of this tremendous acceleration, the temperature corresponding to the atoms' kinetic energy increases from 0.1 degrees Kelvin to thousands of degrees Kelvin in less than a microsecond."

At this point, the speeding atoms separate into an electron and an ion rotating in parallel around the nanowire, completing each orbit in just a few trillionths of a second. The electron eventually gets sucked into the nanotube via quantum tunneling, causing its companion ion to shoot away -- repelled by the strong charge of the 300-volt nanotube -- at a speed of roughly 26 kilometers per second, or 59,000 miles per hour.

The entire experiment was conducted with great precision, allowing the scientists unprecedented access to both cold-atom and nanoscale processes.

"Cold-atom and nanoscale science have each provided exciting new systems for study and applications," says Golovchenko, Rumford Professor of Physics and Gordon McKay Professor of Applied Physics at Harvard. "This is the first experimental realization of a combined cold atom-nanostructure system. Our system demonstrates sensitive probing of atom, electron, and ion dynamics at the nanoscale."

The single-walled carbon nanotube used in these researchers' successful experiment was dubbed "Lucy," and its contributions are acknowledged in the Physical Review Letters paper. The nanotube was grown by chemical vapor deposition across a 10-micron gap in a silicon chip that provides the nanowire with both mechanical support and electrical contact.

"From the atom's point of view, the nanotube is infinitely long and thin, creating a singular effect on the atom," Hau says. ###

This work was supported by the Air Force Office of Scientific Research and the National Science Foundation.

Contact: Steve Bradt steve_bradt@harvard.edu 617-496-8070 Harvard University

Sunday, May 09, 2010

Chip checks for oral cancer

Rice's nano-bio-chip effective in pilot study to detect premalignancies

The gentle touch of a lesion on the tongue or cheek with a brush can help detect oral cancer with success rates comparable to more invasive techniques, according to preliminary studies by researchers at Rice University, the University of Texas Health Science Centers at Houston and San Antonio and the University of Texas M.D. Anderson Cancer Center.

The test that uses Rice's diagnostic nano-bio-chip was found to be 97 percent "sensitive" and 93 percent specific in detecting which patients had malignant or premalignant lesions, results that compared well with traditional tests.

John McDevitt

Rice Professor John McDevitt holds the LabNow device to read nano-bio-chips that will look for signs of oral cancer and other diseases. Photo by Jeff Fitlow
The study appeared online in the journal Cancer Prevention Research.

"One of the key discoveries in this paper is to show that the miniaturized, noninvasive approach produces about the same result as the pathologists do," said John McDevitt, the Brown-Wiess Professor of Chemistry and Bioengineering at Rice. His lab developed the novel nano-bio-chip technology at the university's BioScience Research Collaborative.

Oral cancer afflicts more than 300,000 people a year, including 35,000 in the United States alone. The five-year survival rate is 60 percent, but if cancer is detected early, that rate rises to 90 percent.

McDevitt and his team are working to create an inexpensive chip that can differentiate premalignancies from the 95 percent of lesions that will not become cancerous.
The minimally invasive technique would deliver results in 15 minutes instead of several days, as lab-based diagnostics do now; and instead of an invasive, painful biopsy, this new procedure requires just a light brush of the lesion on the cheek or tongue with an instrument that looks like a toothbrush.

"This area of diagnostics and testing has been terribly challenging for the scientific and clinical community," said McDevitt, who came to Rice from the University of Texas at Austin in 2009. "Part of the problem is that there are no good tools currently available that work in a reliable way."

He said patients with suspicious lesions, usually discovered by dentists or oral surgeons, end up getting scalpel or punch biopsies as often as every six months. "People trained in this area don't have any trouble finding lesions," McDevitt said. "The issue is the next step -- taking a chunk of someone's cheek. The heart of this paper is developing a more humane and less painful way to do that diagnosis, and our technique has shown remarkable success in early trials."

The way forward is with nano-bio-chips -- small, semiconductor-based devices that combine the ability to capture, stain and analyze biomarkers for a variety of health woes that also include cardiac disease, HIV and trauma injuries. Researchers hope the eventual deployment of nano-bio-chips will dramatically cut the cost of medical diagnostics and contribute significantly to the task of bringing quality health care to the world.

The new study compared results of traditional diagnostic tests with those obtained with nano-bio-chips on a small sample of 52 participants, all of whom had visible oral lesions, leukoplakia or erythroplakia and had been referred to specialists for surgical biopsies or removal of the lesions. Of those patients, 11 were diagnosed as healthy.

The chips should also be able to see when an abnormality turns precancerous. "You want to catch it early on, as it's transforming from pre-cancer to the earliest stages of cancer, and get it in stage one. Then the five-year survival rate is very high," he said. "Currently, most of the time, it's captured in stage three, when the survivability is very low."

The device is on the verge of entering a more extensive trial that will involve 500 patients in Houston, San Antonio and England. That could lead to an application for FDA approval in two to four years.

Eventually, McDevitt said, dentists may be the first line of defense against oral cancers, with the ability to catch early signs of the disease right there in the chair. ###

McDevitt's co-authors include Rice senior research scientist Pierre Floriano, Rice postdoctoral associate Shannon Weigum and Spencer Redding, a professor and chair of the Department of Dental Diagnostic Science at the University of Texas Health Science Center at San Antonio (UTHSC).

Also contributing were Chih-Ko Yeh, Stephen Westbrook and Alan Lin of the Department of Dental Diagnostic Science, H. Stan McGuff of the Department of Pathology and Frank Miller, Fred Villarreal and Stephanie Rowan of the Department of Otolaryngology, Head and Neck Surgery, all at the UTHSC at San Antonio; Nadarajah Vigneswaran of the Department of Diagnostic Science, UTHSC at Houston; and Michelle Williams of the Department of Pathology at M.D. Anderson Cancer Center.

The researchers received a Grand Opportunity Grant from the National Institute for Dental and Craniofacial Research Division of the National Institutes of Health for the work.

Contact: David Ruth druth@rice.edu 713-348-6327 Rice University