Monday, December 31, 2007

Nanoscale details of photolithography process

Photolithography Process

Title: Photolithography Process. Description: Schematic of the photolithography process shows the formation of a gradient extending from the photoresist material to be removed (center) into the unexposed portions of the resist on the sides. NIST measurements document the residual swelling fraction caused by the developer that can contribute to roughness in the final developed image.

Source: National Institute of Standards and Technology. Credit Line as it should
appear in print: Credit: NIST. AV Number: 07NCNR002. Date Created: December 2007. Date Entered: 12/11/2007
New paper reveals nanoscale details of photolithography process

Scientists at the National Institute of Standards and Technology (NIST) have made the first direct measurements of the infinitesimal expansion and collapse of thin polymer films used in the manufacture of advanced semiconductor devices. It’s a matter of only a couple of nanometers, but it can be enough to affect the performance of next-generation chip manufacturing. The NIST measurements, detailed in a new paper,* offer a new insight into the complex chemistry that enables the mass production of powerful new integrated circuits.

The smallest critical features in memory or processor chips include transistor “gates.” In today’s most advanced chips, gate length is about 45 nanometers, and the industry is aiming for 32-nanometer gates.
To build the nearly one billion transistors in modern microprocessors, manufacturers use photolithography, the high-tech, nanoscale version of printing technology. The semiconductor wafer is coated with a thin film of photoresist, a polymer-based formulation, and exposed with a desired pattern using masks and short wavelength light (193 nm). The light changes the solubility of the exposed portions of the resist, and a developer fluid is used to wash the resist away, leaving the pattern which is used for further processing.

Exactly what happens at the interface between the exposed and unexposed photoresist has become an important issue for the design of 32-nanometer processes. Most of the exposed areas of the photoresist swell slightly and dissolve away when washed with the developer. However this swelling can induce the polymer formulation to separate (like oil and water) and alter the unexposed portions of the resist at the edges of the pattern, roughening the edge. For a 32-nanometer feature, manufacturers want to hold this roughness to at most about two or three nanometers.

Industry models of the process have assumed a fairly simple relationship in which edge roughness in the exposed “latent” image in the photoresist transfers directly to the developed pattern, but the NIST measurements reveal a much more complicated process. By substituting deuterium-based heavy water in the chemistry, the NIST team was able to use neutrons to observe the entire process at a nanometer scale. They found that at the edges of exposed areas the photoresist components interact to allow the developer to penetrate several nanometers into the unexposed resist. This interface region swells up and remains swollen during the rinsing process, collapsing when the surface is dried. The magnitude of the swelling is significantly larger than the molecules in the resist, and the end effect can limit the ability of the photoresist to achieve the needed edge resolution. On the plus side, say the researchers, their measurements give new insight into how the resist chemistry could be modified to control the swelling to optimal levels. ###

The research, funded by SEMATECH, is part of a NIST-industry effort to better understand the complex chemistry of photoresists in order to meet the needs of next-generation photolithography.

* V.M. Prabhu, B.D. Vogt, S. Kang , A. Rao , E.K. Lin and S.K. Satija. Direct measurement of the spatial extent of the in situ developed latent image by neutron reflectivity. Journal of Vacuum Science and Technology B, 25(6), 2514-2520 (2007).

Contact: Michael Baum 301-975-2763 National Institute of Standards and Technology (NIST)

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Sunday, December 30, 2007

NIST imaging system maps nanomechanical properties

Atomic Force Microscope

Title: Atomic Force Microscope. Description: An atomic force microscope normally reveals the topography of a composite material (l.) NIST's new apparatus adds software and electronics to map nanomechanical properties (r.) The NIST system reveals that the glass fibers are stiffer than the surrounding polymer matrix but sometimes soften at their cores.

Type: Graphic/scientific data. Source: National Institute of Standards and Technology . Credit Line as it should appear in print: Credit: DC Hurley/NIST. AV Number: 07EEEL017. Date Created: December 2007. Date Entered: 12/11/2007
The National Institute of Standards and Technology (NIST) has developed an imaging system that quickly maps the mechanical properties of materials—how stiff or stretchy they are, for example—at scales on the order of billionths of a meter. The new tool can be a cost-effective way to design and characterize mixed nanoscale materials such as composites or thin-film structures.

The NIST nanomechanical mapper uses custom software and electronics to process data acquired by a conventional atomic force microscope (AFM), transforming the microscope’s normal topographical maps of surfaces into precise two-dimensional representations of mechanical properties near the surface. The images enable scientists to see variations in elasticity, adhesion or friction, which may vary in different materials even after they are mixed together. The NIST system, described fully for the first time in a new paper,* can make an image in minutes whereas competing systems might take an entire day.
The images are based on measurements and interpretations of changes in frequency as a vibrating AFM tip scans a surface. Such measurements have commonly been made at stationary positions, but until now 2D imaging at many points across a sample has been too slow to be practical. The NIST DSP-RTS system (for digital signal processor-based resonance tracking system) has the special feature of locking onto and tracking changes in frequency as the tip moves over a surface. Mechanical properties of a sample are deduced from calculations based on measurements of the vibrational frequencies of the AFM tip in the air and changes in frequency when the tip contacts the material surface.

NIST materials researchers have used the system to map elastic properties of thin films with finer spatial resolution than is possible with other tools. The DSP-RTS can produce a 256 × 256 pixel image with micrometer-scale dimensions in 20 to 25 minutes. The new system also is modular and offers greater flexibility than competing approaches. Adding capability to map additional materials properties can be as simple as updating the software. ###

* A.B. Kos and D.C. Hurley. Nanomechanical mapping with resonance tracking scanned probe microscope. Measurement Science and Technology 19 (2008) 015504.

Contact: Laura Ost 303-497-4880 National Institute of Standards and Technology (NIST)

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Saturday, December 29, 2007

Fuel cells help make noisy, hot generators a thing of the past

Hydrogen for Use in the On-Board Fuel Cell

Caption: The process of converting JP-8 into hydrogen for use in the on-board fuel cell. Credit: Pacific Northwest National Laboratory. Usage Restrictions: None
Advances in fuel desulfurization and reforming lead to a successful demonstration of a portable fuel cell system using JP-8 military jet fuel

Two core technologies developed at the Department of Energy's Pacific Northwest National Laboratory - a fuel desulfurization system and a fuel reforming system - were instrumental in the demonstration of an electric power system operating on JP-8, a fuel commonly used in military operations.

Portable fuel cell power units are quieter, more efficient and have lower emissions than standard diesel generators, but are challenged when used with JP-8 fuel because of its sulfur content.
The fuel desulfurization and reforming systems developed at PNNL reduce the sulfur content of JP-8 and generate a hydrogen stream compatible with an integrated fuel cell.

"Running a noisy, hot generator in a war zone is inefficient and can give away your position," said Dale King, project manager at PNNL. "Not running it can leave you without power for communications and other critical systems."

Although currently under development for military use, the desulfurization and reforming technologies can be used with different liquid fuels to provide portable power almost anywhere that small size and high performance are important. Researchers at PNNL are also extending the desulfurization technology for use with diesel fuel.

The fuel cell-centric auxiliary power unit is modular and can be reconfigured for a wide range of uses. Researchers envision the technology being used to supply auxiliary power and heat for long-haul commercial trucks, which would replace the need to run less efficient internal combustion engines while the vehicle is stopped. Battelle, which operates PNNL for DOE, operated a prototype system demonstrating these technologies during the three-day 2007 Fuel Cell Seminar this fall. During the demonstration, an integrated 5-kilowatt electric power system successfully powered area lights and a commercial refrigerator.

A unique catalytic hydrodesulfurization process developed by PNNL removes sulfur from the JP-8 fuel using syngas as the co-reactant in place of hydrogen. Gas phase operation of the process allows for a significant increase in throughput and decrease in operating pressure compared with conventional technology. The process doesn't require consumables or periodic regeneration. The system was developed with funding from the U.S. Army Tank Automotive Research, Development and Engineering Center.

Fuel cells combine hydrogen and oxygen to produce electrical energy with water and heat as by-products. The process is clean, quiet and highly efficient - potentially up to three times more efficient than internal combustion engines. Envisioned benefits include reduced emissions, increased reliability, multi-fuel capability, durability and ease of maintenance. ###

Contact: Christy Lambert 509-375-3732 DOE/Pacific Northwest National Laboratory

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Friday, December 28, 2007

Ames Laboratory researchers solve fuel-cell membrane structure conundrum

Methanol fuel cell Photo: NASA

Methanol fuel cell. The actual fuel cell stack is the layered bi-cubic structure in the center of the image Photo: NASA
New model proposes parallel cylindrical water nanochannels

AMES, Iowa – Fuel-cell cars are reaching commercial viability in today’s increasingly eco-conscious society, but despite their promise, even scientists have struggled to explain just how the fuel-cell’s central component – the proton exchange membrane – really works.

However, a team of researchers at the U.S. Department of Energy’s Ames Laboratory has offered a new model that provides the best explanation to date for the membrane’s structure and how it functions. And armed with that information, scientists should be able to build similar fuel-cell membrane materials that are less expensive or have different properties, such as higher operating temperatures.
A fuel cell works by pumping hydrogen gas through the proton exchange membrane. In the process, the hydrogen gives up electrons in the form of electricity, then combines with oxygen gas to form water as the by-product. It can also work in reverse – when current is applied, water is split into its component gases, hydrogen and oxygen.

The model proposed by Ames Laboratory scientists Klaus Schmidt-Rohr and Qiang Chen, and detailed in the Dec. 9 issue of the journal Nature Materials, looked specifically at Nafion®, a widely used perfluorinated polymer film that stands out for its high selective permeability to water and protons. Schmidt-Rohr, who is also a professor of chemistry at Iowa State University, suggests that Nafion® has a closely packed network of nanoscale cylindrical water channels running in parallel through the material.

“From nuclear magnetic resonance (NMR), we know that Nafion® molecules have a rigid backbone structure with hair-like ‘defects’ along the chain,” Schmidt-Rohr said, “but we didn’t know just how these molecule were arranged. Some have proposed spheroidal water clusters, others a web-like network of water channels.”

“Our theory is that these hydrophobic (water-hating) backbone structures cluster together,” he continued, “to form long rigid cylinders about 2.5 nanometers in diameter with the hydrophilic ‘hairs’ to the inside of the water-filled tubes.”

Though the cylinders in different parts of the sample may not align perfectly, they do connect to create water channels passing through the membrane material, which can be 10’s of microns thick. It’s this structure of relatively wide diameter channels, densely packed and running mostly parallel through the material that helps explain how water and protons can so easily diffuse through Nafion®, “almost as easily as water passing through water” Schmidt-Rohr said.

To unlock the structure mystery, Schmidt-Rohr turned to mathematical modeling of small-angle X-ray and neutron scattering, or SAXS/SANS. X-ray or neutron radiation is scattered by the sample and the resulting scattering pattern is analyzed to provide information about the size, shape and orientation of the components of the sample on the nanometer scale.

Using an algorithm known as multidimensional Fourier transformation, Schmidt-Rohr was able to show that his model of long, densely packed channels closely matches the known scattering data of Nafion®. Mathematical modeling of other proposed structures, in which the water clusters have other shapes or connectivities, did not match the measured scattering curves.

“Our model also helps explain how conductivity continues even well below the freezing point of water,” Schmidt-Rohr said. “While water would freeze in the larger channels, it would continue to diffuse in the smaller-diameter pores.”

Schmidt-Rohr added that additional analysis is needed to determine how the cylinders connect through the membrane. ###

The research is funded by the Department of Energy’s Office of Basic Energy Sciences and conducted by Ames Laboratory’s Materials Chemistry and Biomolecular Material Program.

Ames Laboratory, celebrating its 60th anniversary in 2007, is operated for the Department of Energy by Iowa State University. The Lab conducts research into various areas of national concern, including the synthesis and study of new materials, energy resources, high-speed computer design, and environmental cleanup and restoration.

Contact: Kerry Gibson 515-294-1405 DOE/Ames Laboratory

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Thursday, December 27, 2007

Explosives at the microscopic scale produce shocking results VIDEO

simulation of detonating nitromethane at three different times
Snapshots during a simulation of detonating nitromethane at three different times. At 5 picoseconds behind the detonation shock front (1 picosecond = one millionth of a millionth of one second), the shock has compressed the nitromethane molecules into a hot, dense liquid-like state. The first reactions occur around 8 picoseconds: hydrogen atoms are transferred to the oxygen atoms on the same molecule (white circles).
Near the end of the simulation at 96 picoseconds, a mixture of transient and stable molecules exist including H2O, CO2, and HNC, HNCO. (Carbon=green, Hydrogen=white, Nitrogen=blue, Oxygen=red.) High Resolution Image

LIVERMORE, Calif. -- U.S. troops blew up enemy bridges with explosives in World War II to slow the advance of supplies or enemy forces.

In modern times, patrollers use explosives at ski resorts to purposely create avalanches so the runs are safer when skiers arrive.

Other than creating the desired effect (a destroyed bridge or avalanche), the users didn’t exactly know the microscopic details and extreme states of matter found within a detonating high explosive.

In fact, most scientists don’t know what happens either.
rapid chemical reactions in an energetic material.

Sparks are emitted from rapid chemical reactions in an energetic material. This zoomed microscopic view shows a mixture of reaction intermediates observed during a computer simulation of detonating nitromethane. High Resolution Image
But researchers from Lawrence Livermore National Laboratory and the Massachusetts Institute of Technology have created the first quantum molecular dynamics simulation of a shocked explosive near detonation conditions, to reveal what happens at the microscopic scale.

What they found is quite riveting: The explosive, nitromethane, undergoes a chemical decomposition and a transformation into a semi-metallic state for a limited distance behind the detonation front.

Nitromethane is a more energetic high explosive than TNT, although TNT has a higher velocity of detonation and shattering power against hard targets. Nitromethane is oxygen poor, but when mixed with ammonium nitrate can be extremely lethal, such as in the bombing of the Alfred P. Murrah Federal Building in Oklahoma City.
“Despite the extensive production and use of explosives for more than a century, their basic microscopic properties during detonation haven’t been unraveled,” said Evan Reed, the lead author of a paper appearing in the Dec. 9 online edition of the journal, Nature Physics. “We’ve gotten the first glimpse of the properties by performing the first quantum molecular dynamics simulation.”

In 2005 alone, 3.2 billion kilograms of explosives were sold in the United States for a wide range of applications, including mining, demolition and military applications.
Nitromethane is burned as a fuel in drag racing autos, but also can be made to detonate, a special kind of burning in which the material undergoes a much faster and far more violent type of chemical transformation. With its single nitrogen dioxide (NO2) group, it is a simple representative version of explosives with more NO2 groups.
Though it is an optically transparent, electrically insulating material, it undergoes a shocking transformation: It turns into an optically reflecting, nearly metallic state for a short time behind the detonation shock wave front.

But further behind the wave front, the material returns to being optically transparent and electrically insulating.

“This is the first observation of this behavior in a molecular dynamics simulation of a shocked material,” Reed said. “Ultimately, we may be able to create computer simulations of detonation properties of new, yet-to-be synthesized designer explosives.” ###

Other Livermore researchers include M. Riad Manaa, Laurence Fried, Kurt Glaesemann and J.D. Joannopoulos of MIT.

The work was funded by the Laboratory Directed Research and Development program.

Founded in 1952, Lawrence Livermore National Laboratory is a national security laboratory, with a mission to ensure national security and apply science and technology to the important issues of our time. Lawrence Livermore National Laboratory is managed by Lawrence Livermore National Security, LLC for the U.S. Department of Energy's National Nuclear Security Administration.

Contact: Anne Stark 925-422-9799 DOE/Lawrence Livermore National Laboratory

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Wednesday, December 26, 2007

Clemson researcher studies carbon fibers for nuclear reactor safety

Clemson University chemical engineering professor Amod OgaleCLEMSON, S.C. –– Carbon fibers that are only one-tenth the size of a human hair, but three times stronger than steel, may hold up to the intense heat and radiation of next generation nuclear power generators, providing a safety mechanism. The “Gen IV” power-generating reactors are being designed to provide low-cost electricity, but with a built-in safety mechanism current reactors do not have. High Resolution Image
The Department of Energy (DoE) has awarded chemical engineering professor Amod Ogale, deputy director of the Center for Advanced Engineering Fibers and Films (CAEFF), a $450,000 grant to research carbon fibers embedded into a carbon matrix that do not melt in extreme temperatures for potential use in Gen IV power generators. Presently, about 20 percent of electricity produced in the United States is from nuclear sources.

“One proposed design of the next generation of nuclear plants will consist of a helium-cooled generator that will operate in the range of 1,200 to 1,800 degrees Fahrenheit,” says Ogale. “A critical safety requirement for this reactor is that it can shut down safely in the event of a malfunction where coolant flow is interrupted. Steel alloys currently used internally in reactors melt at the peak temperature of 2500 degrees Fahrenheit, where carbon fiber composites do not.”

Carbon fiber composites are already used successfully in jetliner brake systems because of their ability to withstand high temperatures without melting. However, their performance in a nuclear environment is not adequately understood.

Ogale and his team will study the neutron-radiation damage effects on carbon fibers.

His prior research has shown that including carbon nanotubes (large molecules of carbon that are tube-shaped and 30 nanometers in size) in carbon fibers leads to the development of a more uniform texture that improves the properties of the ultra-thin carbon fibers.

In his research, Ogale expects to generate high graphitic crystallinity, a solid ordered pattern which is evenly distributed so that any changes in fiber properties due to radiation can be minimized.

Irradiation experiments will be conducted in collaboration with researchers at Oak Ridge National Labs. South Carolina State University researchers also will participate in the study.

“This research will lead to a fundamental understanding of how the nanotubes set themselves up to provide radiation-damage tolerance to carbon fibers,” said Ogale. ###

Editors: This material is based upon work supported by DoE under grant number DE-FG02-07ER46364. Any opinions, findings and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of DoE.

Contact: Amod Ogale 864-656-5483. WRITER: Susan Polowczuk, (864) 656-2063, Eeb: Clemson University

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Tuesday, December 25, 2007

Using carbon nanotubes to seek and destroy anthrax toxin and other harmful proteins VIDEO

Deactivating Anthrax Toxin With Nanotubes and Light

Caption: Transmission electron microscope images show carbon nanotubes conjugated with anthrax toxin before (a, b) and after (c, d) exposure to ultraviolet light. This light caused the adsorbed toxin to deactivate and fall off the nanotube, which is why the structures in pictures c and d are smaller in diameter than those in pictures a and b. Credit: Rensselaer/Ravi Kane Usage Restrictions: Please include credit line
New technology could enable new cancer treatment techniques and antibacterial coatings.

Troy, N.Y. – Researchers at Rensselaer Polytechnic Institute have developed a new way to seek out specific proteins, including dangerous proteins such as anthrax toxin, and render them harmless using nothing but light. The technique lends itself to the creation of new antibacterial and antimicrobial films to help curb the spread of germs, and also holds promise for new methods of seeking out and killing tumors in the human body.

Scientists have long been interested in wrapping proteins around carbon nanotubes, and the process is used for various applications in imaging, biosensing, and cellular delivery.
But this new study at Rensselaer is the first to remotely control the activity of these conjugated nanotubes. Details of the project are outlined in the article “Nanotube-Assisted Protein Deactivation” in the December issue of Nature Nanotechnology.
A team of Rensselaer researchers led by Ravi S. Kane, professor of chemical and biological engineering, has worked for nearly a year to develop a means to remotely deactivate protein-wrapped carbon nanotubes by exposing them to invisible and near-infrared light. The group demonstrated this method by successfully deactivating anthrax toxin and other proteins.
“By attaching peptides to carbon nanotubes, we gave them the ability to selectively recognize a protein of interest – in this case anthrax toxin – from a mixture of different proteins,” Kane said. “Then, by exposing the mixture to light, we could selectively deactivate this protein without disturbing the other proteins in the mixture.”

By conjugating carbon nanotubes with different peptides, this process can be easily tailored to work on other harmful proteins, Kane said. Also, employing different wavelengths of light that can pass harmlessly through the human body, the remote control process will also be able to target and deactivate specific proteins or toxins in the human body. Shining light on the conjugated carbon nanotubes creates free radicals, called reactive oxygen species. It was the presence of radicals, Kane said, that deactivated the proteins.

Kane’s new method for selective nanotube-assisted protein deactivation could be used in defense, homeland security, and laboratory settings to destroy harmful toxins and pathogens. The method could also offer a new method for the targeted destruction of tumor cells. By conjugating carbon nanotubes with peptides engineered to seek out specific cancer cells, and then releasing those nanotubes into a patient, doctors may be able to use this remote protein deactivation technology as a powerful tool to prevent the spread of cancer.

Kane’s team also developed a thin, clear film made of carbon nanotubes that employs this technology. This self-cleaning film may be fashioned into a coating that – at the flip of a light switch – could help prevent the spread of harmful bacteria, toxins, and microbes.

“The ability of these coatings to generate reactive oxygen species upon exposure to light might allow these coatings to kill any bacteria that have attached to them,” Kane said. “You could use these transparent coatings on countertops, doorknobs, in hospitals or airplanes – essentially any surface, inside or outside, that might be exposed to harmful contaminants.”

Kane said he and his team will continue to hone this new technology and further explore its potential applications. ###

Co-authors of the paper include Department of Chemical and Biological Engineering graduate students Amit Joshi and Shyam Sundhar Bale; postdoctoral researcher Supriya Punyani; Rensselaer Nanotechnology Center Laboratory Manager Hoichang Yang; and professor Theodorian Borca-Tasciuc of the Department of Mechanical, Aerospace, and Nuclear Engineering.

The group has filed a patent disclosure for their new selective nanotube-assisted protein deactivation technology. The research project was funded by the U.S. National Institutes of Health and the National Science Foundation.

About Rensselaer

Rensselaer Polytechnic Institute, founded in 1824, is the nation’s oldest technological university. The university offers bachelor’s, master’s, and doctoral degrees in engineering, the sciences, information technology, architecture, management, and the humanities and social sciences. Institute programs serve undergraduates, graduate students, and working professionals around the world. Rensselaer faculty are known for pre-eminence in research conducted in a wide range of fields, with particular emphasis in biotechnology, nanotechnology, information technology, and the media arts and technology. The Institute is well known for its success in the transfer of technology from the laboratory to the marketplace so that new discoveries and inventions benefit human life, protect the environment, and strengthen economic development.

Contact: Michael Mullaney 518-276-6161 Rensselaer Polytechnic Institute

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Monday, December 24, 2007

The Library of Congress in Your Wrist Watch?The Library of Congress in Your Wrist Watch?

laser light on 30-nanometer spots using various apertures

Photo Caption: Researchers focused laser light on 30-nanometer spots using various apertures. The c-shaped aperture produced the most powerful result as seen in this scanning near-field optical microscope image by researcher Rabee Ikkawi.
UC Riverside research on nanolasers promise an explosion of memory capacity.

RIVERSIDE, Calif. -- Every advance in memory storage devices presents a new marvel of just how much memory can be squeezed into very small spaces. Considering the potential of nanolasers being developed in Sakhrat Khizroev’s lab at the University of California, Riverside, things are about to get a lot smaller.

As reported in the latest issue of Technology Review, Khizroev is leading a team exploring lasers so tiny that they point to a future where a 10-terabit hard drive is only one-inch square.

That is 50 times the data density of today’s magnetic storage technology, a technology that has nearly reached its limit for continued miniaturization. In response, researchers have been looking for a new leap forward by combining light and magnetism to focus bits of data on much smaller areas on the disk.
The $60 billion a year hard disk drive industry is investigating several new technologies, one of which requires precise nanolasers to help “write” data.

Khizroev, an associate professor of engineering at UCR, and colleagues at the University of Houston led by Professor Dmitri Litvinov, have for the first time achieved a nanolaser which can concentrate light as small as 30 nanometers. For many substances, that is the molecular level. Just as importantly, their nanolaser can focus 250 nanowatts of power, enough to assure effective storage of the information.

The next goal of the researchers is to refine the nanolaser to produce light beams as small as five or 10 nanometers. To achieve this they plan to improve the manufacture of their nanolasers by refining the precision of the focused gallium ion beams used for their fabrication. Khizroev’s lab adapted this technology, commonly used for diagnostics in semiconductor manufacture, to cut the components of their lasers.

He credited the feasibility of this advanced nanomanufacturing on Professor Robert Haddon’s unique nanofabrication facilities at UCR’s Center for Nanoscale Science and Engineering.

Khizroev said there are a number of challenges for getting the tiny disk drives to the market, including lubricating tiny parts and integrating the nanolaser with a recording head. Still, he insisted, the 10-terabit hard drive will be a near-term innovation, appearing in as little as two years.

The implications of the ability to focus light at these scales are even more fantastic in the longer term. The use of photochromic proteins with nanolasers should help lead to nanocomputers and the ability to store still more data in smaller places, Khizroev said. Those proteins paired with nanolasers should also impact energy harvesting and a wide range of medical applications, he added.

Related Links:

Additional Contacts:

Contact: Kris Lovekin 951-827-2495 University of California - Riverside

The University of California, Riverside is a doctoral research university, a living laboratory for groundbreaking exploration of issues critical to Inland Southern California, the state and communities around the world. Reflecting California's diverse culture, UCR's enrollment of about 17,000 is projected to grow to 21,000 students by 2010. The campus is planning a medical school and already has reached the heart of the Coachella Valley by way of the UCR Palm Desert Graduate Center. With an annual statewide economic impact of nearly $1 billion, UCR is actively shaping the region's future. To learn more, visit or call (951) UCR-NEWS

Sunday, December 23, 2007

Nanotube-producing bacteria show manufacturing promise

Nanotube-Producing Bacteria

Caption: Shewanella bacteria (shown in blue) forming nanotubes. Credit: Hor-Gil Hur, GIST. Usage Restrictions: None. Related news release: Nanotube-producing bacteria show manufacturing promise
Nanotubes may have high-tech applications, study involving UCR engineers reports

RIVERSIDE, Calif. – Two engineers at the University of California, Riverside are part of a binational team that has found semiconducting nanotubes produced by living bacteria – a discovery that could help in the creation of a new generation of nanoelectronic devices.

The research team believes this is the first time nanotubes have been shown to be produced by biological rather than chemical means. It opens the door to the possibility of cheaper and more environmentally friendly manufacture of electronic materials.

Study results appear in today's issue of the early edition of the Proceedings of the National Academy of Sciences.
The team, including Nosang V. Myung, associate professor of chemical and environmental engineering in the Bourns College of Engineering, and his postdoctoral researcher Bongyoung Yoo, found the bacterium Shewanella facilitates the formation of arsenic-sulfide nanotubes that have unique physical and chemical properties not produced by chemical agents.

“We have shown that a jar with a bug in it can create potentially useful nanostructures,” Myung said. “Nanotubes are of particular interest in materials science because the useful properties of a substance can be finely tuned according to the diameter and the thickness of the tubes.”

The whole realm of electronic devices which power our world, from computers to solar cells, today depend on chemical manufacturing processes which use tremendous energy, and leave behind toxic metals and chemicals. Myung said a growing movement in science and engineering is looking for ways to produce semiconductors in more ecologically friendly ways.

Two members of the research team, Hor Gil Hur and Ji-Hoon Lee from Gwangju Institute of Science and Technology (GIST), Korea, first discovered something unexpected happening when they attempted to remediate arsenic contamination using the metal-reducing bacterium Shewanella. Myung, who specializes in electro-chemical material synthesis and device fabrication, was able to characterize the resulting nano-material.

The photoactive arsenic-sulfide nanotubes produced by the bacteria behave as metals with electrical and photoconductive properties. The researchers report that these properties may also provide novel functionality for the next generation of semiconductors in nano- and opto-electronic devices.

In a process that is not yet fully understood, the Shewanella bacterium secretes polysacarides that seem to produce the template for the arsenic sulfide nanotubes, Myung explained. The practical significance of this technique would be much greater if a bacterial species were identified that could produce nanotubes of cadmium sulfide or other superior semiconductor materials, he added.

“This is just a first step that points the way to future investigation,” he said. “Each species of Shewanella might have individual implications for manufacturing properties.” ###

Myung, Yoo, Hur and Lee were joined in the research by Min-Gyu Kim, Pohang Accelerator Laboratory, Pohang, Korea; Jongsun Maeng and Takhee Lee, GIST; Alice C. Dohnalkova and James K. Fredrickson, Pacific Northwest National Laboratory, Richland, Wash.; and Michael J. Sadowsky, University of Minnesota.

The Center for Nanoscale Innovation for Defense provided funding for Myung’s contribution to the study.

The University of California, Riverside is a doctoral research university, a living laboratory for groundbreaking exploration of issues critical to Inland Southern California, the state and communities around the world. Reflecting California's diverse culture, UCR's enrollment of about 17,000 is projected to grow to 21,000 students by 2010. The campus is planning a medical school and already has reached the heart of the Coachella Valley by way of the UCR Palm Desert Graduate Center. With an annual statewide economic impact of nearly $1 billion, UCR is actively shaping the region's future. To learn more, visit or call (951) UCR-NEWS.

Contact: Iqbal Pittalwala 951-827-6050 University of California - Riverside

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Saturday, December 22, 2007

Ultrafast optical shutter is switched entirely by laser light

Ultrafast optical shutter is switched entirely by laser light

Carl Kübler stands behind his 12 femtosecond ultrabroadband herahertz laser setup at Konstanz University with summer student Vanessa Knittel, barely visible on the left. Photo: Michael Latz, University of Konstanz
It’s a rare case of all light and no heat: A new study reports that a laser can be used to switch a film of vanadium dioxide back and forth between reflective and transparent states without heating or cooling it.

It is one of the first cases that scientists have found where light can directly produce such a physical transition without changing the material’s temperature.

It is also among the most recent examples of “coherent control,” the use of coherent radiation like laser light to affect the behavior of atomic, molecular or electronic systems. The technique has been used to control photosynthesis and is being used in efforts to create quantum computers and other novel electronic and optical devices. The new discovery opens the possibility of a new generation of ultra-fast optical switches for communications.
The study, which was published in the Sept. 14 issue of Physical Review Letters, was conducted by a team of physicists from Vanderbilt University and the University of Konstanz in Germany headed by Richard Haglund of Vanderbilt and Alfred Leitenstorfer from Konstanz.

Vanadium dioxide’s uncanny ability to switch back and forth between transparent and reflective states is well known. At temperatures below 154 degrees Fahrenheit, vanadium dioxide film is a transparent semiconductor. Heat it to just a few degrees higher, however, and it becomes a reflective metal. The semiconducting and metallic states actually have different crystalline structures. Among a number of possible applications, people have experimented with using vanadium dioxide film as the active ingredient in “thermochromic windows” that can block sunlight when the temperature soars and as microscopic thermometers that could be injected into the body.

In 2005, a research collaboration teaming Haglund and René Lopez (now at the University of North Carolina, Chapel Hill) with Andrea Cavalleri and Matteo Rini from the Lawrence Berkeley National Laboratory tested the vanadium dioxide transition with an ultra-fast laser that produced 120-femtosecond pulses. (A femtosecond is a quadrillionth of a second. At this time scale, an eye blink lasts almost forever. In the three-tenths of a second it takes to blink an eye, light can travel 56,000 miles. By contrast, it takes 100 femtoseconds to cross the width of a human hair.)

Using this laser, the researchers determined that VO2 film can flip from transparent to reflective in a remarkably short time: less than 100 femtoseconds. This was the fastest phase transition ever measured. However, the mechanism that allowed it to make such rapid transitions remained a matter of scientific debate.

Now, in a two-year collaboration with the Leitenstorfer group, the Vanderbilt researchers have used a laser with even shorter, 12-femtosecond pulses to “strobe” the vanadium dioxide transition with the fastest pulses ever used for this purpose. The result" “This transition takes place even faster than we thought possible,” says Haglund. “It can shift from transparent to reflective and back to transparent again in less than 100 femtoseconds, making the transition more than twice as fast as we had thought.”

In order to identify the driving mechanism for the rapid change of state in vanadium dioxide, Leitenstorfer’s graduate student Carl Kübler developed a method that converts the near-infrared photons produced by their 12-femtosecond pulse laser into a broad spectrum of infrared wavelengths that bracket a well-known vibration in the vanadium dioxide crystal lattice. At the same time, the Vanderbilt researchers figured out how to grow VO2 film on a diamond substrate that is transparent to infrared light.

This allowed the researchers to show that the energy in the laser beam goes directly into the crystal lattice of the VO2, driving it to shift from its transparent, crystalline form to its more compact and symmetric metallic configuration.

The laser light doesn’t produce this shift by heating the VO2 lattice until it melts, as the conventional wisdom about phase transitions suggested. Instead, the researchers found that the stream of photons directly drive the oxygen atoms from one position to another by a process that is rather like pumping a swing in time with its natural frequency.

“People have believed for a long time that what happened in this phase transition was that the electrons get excited and then, somehow or another, the crystal structure changes,” says Haglund. “But it turns out that the change in crystal structure is associated with this coherent molecular vibration.”

Such a rapid transition is only possible because the difference between the metallic and semiconductor geometries is extremely small. “You can think of the movement that results as a breathing motion of the oxygen ‘cage’ that surrounds the vanadium ions,” says Haglund. “That makes it possible for the structure to change from the semiconducting to the metallic states. It’s a little like taking a deep breath to get into last summer’s clothes.”

This mechanism also allows the researchers to trigger the transition without changing the film’s temperature. “We can focus the laser beam on a transparent vanadium dioxide film and create a small reflective spot. We can switch it on and off in less than 100 femtoseconds provided we haven’t dumped so much energy into the film that we’ve heated it up. However, the more laser energy you dump in the VO2, the longer it takes to return to the semiconducting state,” Haglund says. ###

Henri Ehrke and Rupert Huber from the University of Konstanz, and Andrej Halabica from Vanderbilt University also collaborated in the study, which was funded by the National Science Foundation and the Alexander von Humboldt Foundation.

Contact: David F. Salisbury 615-343-6803 Vanderbilt University

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Friday, December 21, 2007

Professor Strauf's research is Nature Photonics’ cover article

December 2007 issue of Nature PhotonicsPaper by Strauf and colleagues focuses on ultra-bright single photon source

HOBOKEN, N.J. — Stefan Strauf, Assistant Professor (BIO in PDF) in the Department of Physics & Engineering Physics at Stevens Institute of Technology, along with colleagues from the University of California, Santa Barbara and Leiden University (Netherlands), has authored the article, “High-frequency single-photon source with polarization control,” the cover article of the December 2007 issue of Nature Photonics
The article reports on important advances in high-performance single-photon sources that bring such possibilities closer to reality. In particular, single photons can be used to implement absolutely secure optical communication, also known as Quantum Cryptography. With this new source, recording a single-photon signature that took eight hours five years back can now be achieved on a millisecond time scale. This remarkable progress was achieved by developing a novel type of microcavity structure which strongly enhances the light extraction from the optically active material. Moreover, with the help of embedded electrical gates, the researchers demonstrated suppression of unwanted dead-times in the emission process itself resulting in a net single photon generation rate of 100 MHz into an optical fiber.

As described in the News & Views section of the issue, “More futuristic applications of single photon states include photonic networks designed to achieve scalable quantum computation, which one day will hopefully solve problems exponentially faster than classical computers.”
Strauf also was interviewed by the publication regarding his work on the project. “The traditional approach to generating single photons is to use weak laser pulses. In order to reach the single-photon level, you have to attenuate the light very strongly, limiting the efficiency of the device. Also, the photons emitted are governed by statistics. What we need is a high-efficiency source where we can generate photons one by one. Luckily, nature provides a solution in the form of the two-level system, just like the one we use: self-assembled quantum dots,” said Strauf. ###Stefan Strauf, Assistant Professor in the Department of Physics & Engineering Physics at Stevens Institute of Technology
Strauf’s coauthors on the paper are Nick G. Stoltz (Materials Department, University of California, Santa Barbara); Matthew T. Rakher (Department of Physics, University of California, Santa Barbara); Larry A. Coldren (Materials Department and the ECE department, University of California, Santa Barbara); Pierre M. Petroff (Materials Department and the ECE department, University of California, Santa Barbara); and Dirk Bouwmeester (Department of Physics, University of California, Santa Barbara and Huygens Laboratory, Leiden University, the Netherlands).

About Stevens Institute of Technology: Founded in 1870, Stevens Institute of Technology is one of the leading technological universities in the world dedicated to learning and research. Through its broad-based curricula, nurturing of creative inventiveness, and cross disciplinary research, the Institute is at the forefront of global challenges in engineering, science, and technology management. Partnerships and collaboration between, and among, business, industry, government and other universities contribute to the enriched environment of the Institute.

A new model for technology commercialization in academe, known as Technogenesis®, involves external partners in launching business enterprises to create broad opportunities and shared value. Stevens offers baccalaureates, master’s and doctoral degrees in engineering, science, computer science and management, in addition to a baccalaureate degree in the humanities and liberal arts, and in business and technology.

The university has a total enrollment of 2,040 undergraduate and 3,085 graduate students, and a worldwide online enrollment of 2,250, with about 400 full-time faculty. Stevens’ graduate programs have attracted international participation from China, India, Southeast Asia, Europe and Latin America. Additional information may be obtained from its web page at

For the latest news about Stevens, please visit

Contact: Stephanie Mannino 201-216-5602 Stevens Institute of Technology

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Thursday, December 20, 2007

Technique controls nanoparticle size, makes large numbers

Pratim Biswas, Ph.D., the Stifel and Quinette Jens Professor and chair of the Department of Energy, Environmental and Chemical Engineering

Pratim Biswas has a method that controls the size of the nanoparticles he makes, opening up possibilities for new nanotechnology applications and different techniques. David Kilper/WUSTL Photo
Scaling up the small business

In a world that constantly strives for bigger and bigger, Washington University’s Pratim Biswas, Ph.D., the Stifel and Quinette Jens Professor and chair of the Washington University Department of Energy, Environmental and Chemical Engineering, is working to make things smaller and smaller.

Biswas conducts research on nanoparticles, which are the building blocks for nanotechnology. For the first time, Biswas has shown that he can independently control the size of the nanoparticles that he makes, keeping their other properties the same.
He’s also shown with his technique that the nanoparticles can be made in large quantities in scalable systems, opening up the possibility for more applications and different techniques.

Nanotechnology has far-reaching applications in microelectronics, renewable energy, and medicine, just to name a few. But the first step is synthesizing and understanding nanoparticles.

A nanoparticle is 100 nanometers and a nanometer is 1/1000 of a micrometer. To put it into perspective, a hair is about 50-100 micrometers thick.

“It’s difficult to imagine dividing a meter up into a million pieces and then a nanometer is a thousandth of that,” explained Biswas. “These are very tiny particles.”

This small size is critical in the applications. By varying the size, nanoparticles can efficiently be tuned to perform a specific task, be it cosmetics or pollution clean up.

“When I reduce the size of the object…then the properties are very different. They can have certain unique properties,” said Biswas. “By changing the size and the crystal structure you can tune the functionality.”

Fabulous Flames

To make these nanoparticles and alter their size, Biswas uses a flame aerosol reactor (FLAR). The flame provides a high temperature environment in which molecules can be assembled in a single step.

“Bring the material in, react it, form the particles and then collect it and go and use it,” said Biswas.

This technique also allows for mass production, once the conditions to produce the desired material have been determined. Biswas deals with milligram and gram quantities in the lab, but he indicates that these processes can be readily scaled up to produce larger quantities with a bigger reactor.

Biswas described the technique and his work in the July 2007 issue of Nanotechnology.

Controlling the size of these particles is what opens doors to new and unique uses.

“The applications are plentiful,” said Biswas. “The other thing is, if I can make materials of very narrow sizes, I can study the properties as a function of size, which has not been possible in the past, with very precise controls so we can do fundamental research. And that allows me to come up with new applications.”

Dig those crazy tires

Such new applications may even change the way we think about driving. Tired of boring, black car tires? With nanotechnology, tires could become a fashion statement with red, pink, blue, green, “any color you want” as possibilities.

“All tires are black in color because of the carbon that is added. The color’s not important but now you could add a silica-based material which will allow you to get any color of your choice,” said Biswas. “Nanoparticles are going to be used everywhere. They are already being used in many applications—cosmetics, microelectronics—but now you are going to use it for tires.”

With all of these new applications come budding new fields of study. One area is nanotoxicology, which researches the health and environmental safety of new materials containing nanoparticles. To test safety, nanotechnologists join forces with biologists to determine the safety of different-sized particles. For example, one size particle may provide the best effects in a cosmetic, but manufacturers must make sure that it shouldn’t cause toxic effects in a person’s body.

“We don’t want to just release it to the environment. The general feeling is that you have to be proactive, make sure everything is OK and then go, so here you are trying to be as cautious as possible,” said Biswas.

Biswas’ work focuses mainly on making the nanoparticles, but his research has led to a variety of applications and collaborations. Biswas is currently collaborating with Sam Achilefu, Ph.D., associate professor of radiology in the Washington University School of Medicine. Achilefu is working to selectively deposit imaging agents. Rather than flood a cancer patient’s body with a drug during chemotherapy, for example, nanotechnology and selective deposits could deliver and concentrate the drug in the region of the tumor.

“These are very preliminary results,” said Biswas, “but we’re getting some neat results. So there are some cautious examples, like toxicology, but then there are many useful applications.”

Biswas also stresses the importance in the global marketplace. Nanotechnology has the potential to clean up water to provide drinking water for rural populations worldwide. Such efforts make a “big social message,” said Biswas. Renewable energy is yet another possibility in the realm of nanotechnology.

The possibilities of nanotechnology are endless, and everyday Biswas embarks on this exciting journey.

“That’s the beauty here. At Washington University we have a very strong aerosol science and technology group, I would say one of the strongest, in this area,” said Biswas. “ Furthermore, there are many collaborators in different disciplines where we can explore new application areas. So our ability to make tailor-made nanoparticles with very tight control on properties will allow more applications to be invented. That’s the driving force – the ability to synthesize nanoparticles; they are the building blocks of nanotechnology.” ###

Written by Erin Fults. Contact: Pratim Biswas 314-935-5482 Washington University in St. Louis

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Wednesday, December 19, 2007

Tethered to chip, energy supply that drives sperm could power 'nanobot'

energy supply that drives sperm could power 'nanobot'Presented at American Society for Cell Biology annual meeting

Washington, D.C. -- The biological pathway that powers sperm to swim long distances could be harnessed to nanotech devices, releasing drugs or performing mechanical functions inside the body, according to a presentation at the American Society for Cell Biology’s 47th Annual meeting.

The work by researchers at Cornell’s Baker Institute of Animal Health may be the first demonstration of how multistep biological pathways can be assembled and function on a human-made device.
Mammalian sperm have to delivery energy to the long, thin, whip-like tails that power their swimming. Sperm meet the challenge, in part, by onsite power generation, modifying the enzymes of glycolysis so that they can attach themselves to a solid structure running the major length of the sperm tail. From that secure perch, glycolytic enzymes convert sugar into ATP, supplying energy all along the sperm’s bending and flexing tail.

Chinatsu Mukai, Alex Travis, and others at Cornell’s College of Veterinary Science looked at the early steps in the glycolysis pathway to see if they could move it from the thin “fibrous sheath” that covers the sperm tail to a solid inorganic substitute—a nickel-NTA (nitrilotriacetic acid) chip.
First, the researchers replaced the sperm-specific targeting domain of hexokinase, the first enzyme of glycolysis, with a tag that binds to a special gold surface. Even when tethered, the enzyme remained functional. Next they tagged the second enzyme in the pathway, glucose-6-phosphate isomerase. This too was active when tethered. With both attached to the same support, the enzymes acted in series with the product of the first reaction serving as substrate for the second.Mammalian sperm have to delivery energy to the long, thin, whip-like tails that power their swimming.
These are only the first steps in reproducing the full glycolytic pathway on an inorganic support, say Mukai and Travis. Mukai and Travis suggest that their work serves as proof of principle that the organization of the glycolytic pathway in sperm might provide a natural engineering solution of how to produce ATP locally on nano devices. ###

Paper, Coupled Metabolic Reaction on a Chip: A Step Toward Energy Production on Implantable Medical Devices, Portable power: the sperm’s tail in PDF Format

For more information: Alexander Travis (607) 256-5613, Chinatsu Mukai (607) 256-5622.

ASCB meeting press office. John Fleischman, ASCB science writer: or (513) 929-4633 or Cathy Yarbrough, ASCB meeting information officer: or (858) 243-1814

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Tuesday, December 18, 2007

UCLA researchers discover cancer cells 'feel' much softer than normal cells

Researchers Sarah Cross, Yu-Sheng Jin, Jian Yu Rao and James Gimzewski

Right to left: Researchers Sarah Cross, Yu-Sheng Jin, Jian Yu Rao and James Gimzewski at the Nano and Pico Characterization core lab at UCLA's California NanoSystems Institute. UCLA Newsroom. Advance in Cancer Research High Resolution Image
Nanotechnology method may help doctors detect and treat cancer more effectively.

A multidisciplinary team of UCLA scientists was able to differentiate metastatic cancer cells from normal cells in patient samples using leading-edge nanotechnology that measures the cells' softness.

The study, published in the advance online edition of the journal Nature Nanotechnology, represents one of the first times researchers have been able to take living cells from cancer patients and apply nanotechnology to analyze them and determine which were cancerous and which were not.
The nanoscience measurements may provide a potential new method for detecting cancer — especially in cells from body cavity fluids, where diagnosis using current methods is typically very challenging. The method also may aid in personalizing treatments for patients.

When cancer is becoming metastatic or is invading other organs, the diseased cells must travel throughout the body. Because these cells need to enter the bloodstream and maneuver through tight anatomical spaces, they are much more flexible, or softer, than normal cells. These spreading, invading cancer cells can cause a buildup of fluids in body cavities such as the chest and abdomen. But fluid buildup in patients does not always mean cancer cells are present. If the fluid could be quickly and accurately tested for the presence of cancer, oncologists could make better decisions about how aggressive a treatment should be administered or if any treatment is necessary at all.

In this study, researchers collected fluid from the chest cavities of patients with lung, breast and pancreatic cancers — a relatively non-invasive procedure. One problem with diagnosing metastatic disease in this setting is that cancer cells and normal cells in body cavity fluids look very similar under an optical microscope, said Jianyu Rao, a researcher at UCLA's Jonsson Cancer Center and one of the study's senior authors. Conventional diagnostic methods fail to detect about 30 percent of cases in which cancer cells are present in the fluid.

"We detect cancer cells typically by looking at them under a microscope after the cells are fixed and stained with chemicals, which is really an antiquated method," said Rao, who is also an associate professor of pathology and laboratory medicine at the David Geffen School of Medicine at UCLA. "Usually, the cancer cells have larger nuclei and other subtle features. However, the normal cells from body cavity fluids can look almost identical to cancer cells under an optical microscope. While staining for tumor protein markers could increase diagnostic accuracy, what we were missing was a way to determine if cancer cells have different mechanical properties than normal cells."

Employing one of the most valuable tools in the nanotechnology arsenal, the research team used an atomic force microscope (AFM) to measure cell softness. Since the cells being analyzed were less than half the diameter of a human hair, researchers needed a very precise and delicate instrument to measure resistance in the cell membrane, said chemistry and biochemistry professor James Gimzewski, a member of UCLA's California NanoSystems Institute and also one of the study's senior authors.

"We had to measure the softness of the cell without bursting it," Gimzewski said. "Otherwise, it's like trying to measure the softness of a tomato using a hammer."

The AFM uses a minute, sharp tip on a spring to push against the cell surface and determine the degree of softness. Think of it as an extension of a doctor's hands performing a physical examination to determine disease, Gimzewski said.

"You look at two tomatoes in the supermarket and both are red. One is rotten, but it looks normal," Gimzewski said. "If you pick up the tomatoes and feel them, it's easy to figure out which one is rotten. We're doing the same thing. We're poking and quantitatively measuring the softness of the cells."

After probing a cell, the AFM assigns a value that represents how soft a cell is based on the resistance encountered. What the team found was that the cancer cells were much softer than the normal cells and that the cancer cells were similarly soft with very little variation in gradation. The normal, healthy cells from the same specimen were much stiffer; in fact, the softness values assigned to each group did not overlap at all, making diagnosis using this nanomechanical measurement easier and more accurate.

"It was fascinating to find such striking characteristics between the metastatic cancer cells and normal cells," said Sarah Cross, a UCLA graduate student in chemistry and biochemistry and a study author. "The metastatic cancer cells were extremely soft and easily distinguishable from the normal cells despite similarities in appearance. And we're looking at live cells taken from human patients, so that makes this is a unique finding."

Calvin Quate of Stanford University, the co-inventor of the atomic force microscope, said the UCLA study breaks new ground.

"This manuscript is the first that directly shows a relationship between the nanomechanical properties and physiological function in clinical samples from patients with suspected cancer," said Quate, recipient of the 1992 National Medal of Science.

National breast cancer expert Susan Love said the study findings "open a new era for function-based tumor cell diagnostics."

"With these findings, it is foreseeable that a combined biochemical, biophysical and morphological analysis for analyzing human cytological specimens using the AFM may be finally realized," said Love, president and medical director of the Susan Love Research Foundation and a clinical professor of surgery at UCLA.

Researchers next will explore whether the nanomechanical analysis can be used to personalize cancer treatment based on the characteristics of a patient's cancer cells. There are standard chemotherapy drugs that are used to treat metastatic cancer, Rao said, but response varies from patient to patient. If researchers could test the cancer cells beforehand, they could potentially apply therapies that would make the cells stiffer, making it more difficult for the diseased cells to spread through the body.

The study was a collaboration among the California NanoSystems Institute at UCLA, UCLA's Jonsson Cancer Center, the department of chemistry and biochemistry, and the department pathology and laboratory medicine. In addition to Rao, Gimzewski and Cross, the research team included Yu-Sheng Jin.

UCLA's Jonsson Comprehensive Cancer Center comprises about 235 researchers and clinicians engaged in disease research, prevention, detection, control, treatment and education. One of the nation's largest comprehensive cancer centers, the Jonsson Center is dedicated to promoting research and translating basic science into leading-edge clinical studies. In July 2007, the Jonsson Cancer Center was named the best cancer center in California by U.S. News & World Report, a ranking it has held for eight consecutive years. For more information visit the center's Web site at

The California NanoSystems Institute is a multidisciplinary research center at UCLA whose mission is to encourage university-industry collaboration and to enable the rapid commercialization of discoveries in nanosystems. CNSI members include some of the world's preeminent scientists, and the work conducted at the institute represents world-class expertise in five targeted areas of nanosystems-related research: renewable energy, environmental nanotechnology and nanotoxicology, nanobiotechnology and biomaterials, nanomechanical and nanofluidic systems, and nanoelectronics, photonics and architectonics. For additional information, visit

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Monday, December 17, 2007

Nano-sized voltmeter measures electric fields deep within cells

Raoul Kopelman, Kasimir Fajans Collegiate Professor of Chemistry, Physics and Applied Physics Ph.D., Columbia UniversityANN ARBOR, Mich.---A wireless, nano-scale voltmeter developed at the University of Michigan is overturning conventional wisdom about the physical environment inside cells. It may someday help researchers tackle such tricky medical issues as why cancer cells grow out of control and how damaged nerves might be mended.
U-M professor Raoul Kopelman discussed the device during a special session, "Creating Next Generation Nano Tools for Cell Biology," at the annual meeting of the American Society for Cell Biology in Washington, D.C.

"The basic idea behind this field of research is to follow cellular processes---both normal and abnormal---by monitoring physical properties inside the cell. There's a long history of research on the chemistry happening inside the cell, but now we're getting interested in measuring the physical properties, because physical and chemical processes are related," said Kopelman, who is the Richard Smalley Distinguished University Professor of Chemistry, Physics and Applied Physics.

With a diameter of about 30 nanometers, the spherical device is 1,000-fold smaller than existing voltmeters, Kopelman said. It is a photonic instrument, meaning that it uses light to do its work, rather than the electrons that electronic devices employ.

Kopelman's former postdoctoral fellow Katherine Tyner, now at the U.S. Food and Drug Administration, used the nano-voltmeter to measure electric fields deep inside a cell---a feat that until now was impossible. Scientists have measured electric fields in the membranes that surround cells, but not in the interior, Kopelman said.

With the new approach, the researchers don't simply insert a single voltmeter; they're able to deploy thousands of voltmeters at once, spread throughout the cell. Each unit is a single nano-particle that contains voltage-sensitive dyes. When stimulated with blue light, the dyes emit red and green light, and the ratio of red to green corresponds to the strength of the electric field in the area of interest.

Tyner's measurements revealed surprisingly high electric fields in cytosol---the jellylike material that makes up most of a cell's interior.

"The standard paradigm has been that there are zero electric fields in cytosol," Kopelman said, "but all of the 13 regions we measured had high electric field strength---as high as 15 million volts per meter." In comparison, the electrical field strength inside a typical home is five to 10 volts per meter; directly under a power transmission line, it's 10,000 volts per meter. Kopelman, Tyner and coauthor Martin Philbert, professor of environmental health sciences and associate dean for research at the U-M School of Public Health, published a report on the nano-voltmeter and their paradigm-shattering findings in Biophysical Journal in August.

Those findings leave the researchers wondering why electrical fields exist inside cells.

"I don't know the answer to that," Kopelman said. "I suspect that finding out exactly what's going on will keep a lot of people working for a long time." But the ability to measure internal cellular electrical fields should aid in that endeavor.

It's already known that changes in electrical fields associated with membranes can play a role in diseases such as Alzheimer's, and researchers have been exploring the use of externally-applied electric fields to stimulate wound healing and nerve growth and regeneration.

As for the U-M researchers, Philbert, a neurotoxicologist, is exploring how intracellular fields change with exposure to nerve toxins, and Kopelman, who is collaborating with Philbert and researchers in the U-M medical school on new approaches to cancer detection and treatment, is interested in comparing electric fields in cancerous and non-cancerous cells. But they're also open to other avenues of research, Kopelman said.

"One reason for going to the ASCB meeting is to confer with colleagues and strategize about where to go next." ###

Contact: Nancy Ross-Flanigan 734-647-1853 University of Michigan

The researchers received funding from the Defense Advanced Research Project Agency BioMagnetics program, the National Institutes of Health and the National Science Foundation - Division of Materials Research.

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