David Kirkpatrick

September 10, 2010

Good news from the U.S. Court of Appeals

Federally funded stem cell research back in business. Of course it’s stupid this is even a issue, much less a political football. I wrote out, and deleted, two sentences of snark about christianist theocons, but maybe those thoughts are better left to your imagination. Let’s just say I think the groups pushing against stem cell research are a serious threat to my life, liberty and pursuit of happiness and everyone would be better off if they could just form their own society on an island somewhere and institute whatever manner of holy book law they wanted to live under.

From the link:

A federal appeals court here ruled Thursday that federal financing of embryonic stem cell research could continue while the court considers a judge’s order last month that banned the government from underwriting the work.

The ruling by the United States Court of Appeals could save research mice from being euthanized, cells in petri dishes from starving and scores of scientists from a suspension of paychecks, according to arguments the Obama administration made in the case.

It could also allow the National Institutes of Health to provide $78 million to 44 scientists whose research the agency had previously agreed to finance.

The stay also gives Congress time to consider legislation that would render the ban, and the court case behind it, largely moot, a prospect that some embattled Democrats have welcomed. Despite staunch opposition by some critics, embryonic stem cell research is popular, and a legislative fight on the issue could prove a tonic for Democrats battling a tough political environment.

September 3, 2010

Graphene transistors hit 300 GHz

Via KurzweilAI.net — Great news, but as always I’d love to see a market-ready application come out of this research in the near future. Blogging about nanotech breakthroughs is all well and good, but it is excellent when I get the chance to blog about a real-world application of said breakthroughs.

From the link:

High-speed graphene transistors achieve world-record 300 GHz

September 3, 2010 by Editor

UCLA researchers have fabricated the fastest  graphene transistor to date, using a new fabrication process with a  nanowire as a self-aligned gate.

Self-aligned gates are a key element in modern transistors, which are semiconductor devices used to amplify and switch electronic signals.  Gates are used to switch the transistor between various states, and self-aligned gates were developed to deal with problems of misalignment encountered because of the shrinking scale of electronics.

“This new strategy overcomes two limitations previously encountered in graphene transistors,” professor of chemistry and biochemistry Xiangfeng Duan said. “First, it doesn’t produce any appreciable defects in the graphene during fabrication, so the high carrier mobility is retained. Second, by using a self-aligned approach with a nanowire as the gate, the group was able to overcome alignment difficulties previously encountered and fabricate very short-channel devices with unprecedented performance.”

These advances allowed the team to demonstrate the highest speed graphene transistors to date, with a cutoff frequency up to 300 GHz — comparable to the very best transistors from high-electron mobility materials such gallium arsenide or indium phosphide.

Graphene, a one-atom-thick layer of graphitic carbon, has great potential to make electronic devices such as radios, computers and phones faster and smaller. With the highest known carrier mobility — the speed at which electronic information is transmitted by a material — graphene is a good candidate for high-speed radio-frequency electronics. High-speed radio-frequency electronics may also find wide applications in microwave communication, imaging and radar technologies.

Funding for this research came from the National Science Foundation and the National Institutes of Health.

More info: UCLA news

August 28, 2010

Congress may pass emergency bill to restart stem cell research

And it can’t happen a day too soon. Allowing theocrats to hijack scientific and medical research only puts the United States that much more under the gun of losing dominance  in fields that will — will, not might — have a major influence on human life and the global marketplace in the very near future.

The release:

Congressman, CSHL president urge quick action to reverse judicial embryonic stem cell research ban

A federal judge’s decision ‘sets back’ vital work and handcuffs American science

Cold Spring Harbor, NY – Against a backdrop of some of the world’s most sophisticated biological research labs, Rep. Steve Israel (D-Huntington) this morning issued a challenge to his colleagues in Congress: immediately upon their return from summer recess, he urged, they should pass legislation that would reverse a recent Federal court decision that has brought embryonic stem cell research in the U.S. to a screeching halt.

Rep. Israel was seconded in his plea by Dr. Bruce Stillman, a renowned cancer researcher and President of Cold Spring Harbor Laboratory, which hosted the Congressman’s announcement to the press this morning. Also lending vocal support was Brooke Ellison, a stem cell research advocate and instructor at Stony Brook University, who, since a car accident in 1990, has been a quadriplegic.

Rep. Israel said the Aug. 23 decision by Chief Judge Royce C. Lamberth of the Federal District Court for the District of Columbia, “sets back research, sets back patients, and sets back jobs,” on Long Island and across the nation. The decision, which prevents federally funded research from being conducted on any embryonic stem cells derived from human embryos, “has not only rolled back the Obama policy on stem cells, but has actually rolled back the Bush policy,” Israel noted.

The Congressman said he regards the legal appeals process too slow, given the gravity of the matter. “I don’t think we should wait for an appeal,” he said. “We’ve got to act, and act fast.” Congress has twice in the past decade passed bills giving the go-ahead for embryonic stem cell research. “The Judge said Congress created the policy, and only Congress can revisit it. Well, I want to take him up on that. When we return to Washington on Sept. 14, the House, as one of its first priorities, should re-pass the very legislation that it has passed twice before.” If passed by the Senate, such a bill would be almost certain to receive a presidential signature, thus ending any ambiguity about the will of Congress, Israel said.

President Stillman of Cold Spring Harbor Laboratory praised Rep. Israel for taking a strong position on the issue and calling for an immediate remedy. “To the scientific community,” Dr. Stillman said, “this judicial decision was an absolute shock. Embryonic stem cells have been studied since the 1980s, and now the work has been forced to a complete stop. The judge’s decision reverses the policies of two presidents, goes far beyond the debate that we’ve seen in this country, and sets a standard that is unique in the world. This is now the only country in the world where you cannot do embryonic stem cell research.”

Dr. Stillman said he believed that bringing the matter before Congress once more “will not only clarify the situation,” but will provide Congress with a golden opportunity “to make a strong statement to the people of this country and to patients like Brooke Ellison, who are counting on steady progress in stem cell research.” The prior passage by Congress of two bills enabling research with embryonic stem cells is evidence of the strong public support that exists for this type of research, Stillman said.

Brooke Ellison, who spoke from her wheelchair, said that “stem cell research has been used as a political see-saw,” subject to the uncertainties of the political process. “But this is not a political, judicial or ideological issue,” she said. “It’s a human issue. One that speaks to the very core of what it means to show basic human compassion.”

Dr. Stillman said that while most work involving stem cells at CSHL was not embryonic stem cell research, any labs in which embryonic cells are used will now be subject to the National Institutes of Health’s recent interpretation of Judge Lamberth’s ruling. He said there was still some ambiguity about whether the interpretation will hold up under inevitable challenge. But the point, Dr. Stillman emphasized, is that science cannot properly proceed and the therapeutic potential of embryonic stem cells cannot be discovered — by researchers working in America — unless research is permitted to proceed in unfettered fashion.

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Cold Spring Harbor Laboratory (CSHL) is a private, not-for-profit research and education institution at the forefront of efforts in molecular biology and genetics to generate knowledge that will yield better diagnostics and treatments for cancer, neurological diseases and other major causes of human suffering. For more information, visit www.cshl.edu.

August 26, 2010

Cool nanotech image — microneedles

Cool to look, even more cool when put into practice. Microneedles can deliver quantum dots into skin and should lead to new diagnosis and treatment of medical conditions such as skin cancer.

And now, the image:

Hollow microneedles open the door to new techniques for diagnosing and treating a variety of medical conditions, including skin cancer. Image reproduced by permission of the Royal Society of Chemistry.

For more on microneedles, here’s the full release.

August 19, 2010

Yoga improves your mood

I have no doubt about this research. This year I’ve become a huge pusher of Wii Fit Plus, and I regularly do about a thirty minute yoga workout on the balance board. I’m as flexible as I’ve ever been, and according to this research my mood is better and I have less anxiety for my efforts. All I know is it’s pretty fun and more than a little bit cool to work out with an on-screen trainer putting you through the paces.

From the second link, the release:

New study finds new connection between yoga and mood

Boston, MA—Researchers from Boston University School of Medicine (BUSM) have found that yoga may be superior to other forms of exercise in its positive effect on mood and anxiety. The findings, which currently appear on-line at Journal of Alternative and Complementary Medicine, is the first to demonstrate an association between yoga postures, increased GABA levels and decreased anxiety.

The researchers set out to contrast the brain gamma-aminobutyric (GABA) levels of yoga subjects with those of participants who spent time walking. Low GABA levels are associated with depression and other widespread anxiety disorders.

The researchers followed two randomized groups of healthy individuals over a 12-week long period. One group practiced yoga three times a week for one hour, while the remaining subjects walked for the same period of time. Using magnetic resonance spectroscopic (MRS) imaging, the participants’ brains were scanned before the study began. At week 12, the researchers compared the GABA levels of both groups before and after their final 60-minute session.

Each subject was also asked to assess his or her psychological state at several points throughout the study, and those who practiced yoga reported a more significant decrease in anxiety and greater improvements in mood than those who walked. “Over time, positive changes in these reports were associated with climbing GABA levels,” said lead author Chris Streeter, MD, an associate professor of psychiatry and neurology at BUSM.

According to Streeter, this promising research warrants further study of the relationship between yoga and mood, and suggests that the practice of yoga be considered as a potential therapy for certain mental disorders.

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Funding for this study was provided by the National Institutes of Health.

April 6, 2010

Nanotech and medicine

New research on how carbon nanotubes may be used in medical applications.

The release:

[PRESS RELEASE, 5 April 2010] A team of Swedish and American scientists has shown for the first time that carbon nanotubes can be broken down by an enzyme – myeloperoxidase (MPO) – found in white blood cells. Their discoveries are presented in Nature Nanotechnology and contradict what was previously believed, that carbon nanotubes are not broken down in the body or in nature. The scientists hope that this new understanding of how MPO converts carbon nanotubes into water and carbon dioxide can be of significance to medicine.

“Previous studies have shown that carbon nanotubes could be used for introducing drugs or other substances into human cells,” says Bengt Fadeel, associate professor at the Swedish medical university Karolinska Institutet. “The problem has been not knowing how to control the breakdown of the nanotubes, which can caused unwanted toxicity and tissue damage. Our study now shows how they can be broken down biologically into harmless components.”

Carbon nanotubes are a material consisting of a single layer of carbon atoms rolled into a tube with a diameter of only a couple of nanometres (1 nanometer = 1 billionth of a metre) and a length that can range from tens of nanometres up to several micrometers. Carbon nanotubes are lighter and stronger than steel, and have exceptional heat-conductive and electrical properties. They are manufactured on an industrial scale, mainly for engineering purposes but also for some consumer products.

Carbon nanotubes were once considered biopersistent in that they did not break down in body tissue or in nature. In recent years, research has shown that laboratory animals exposed to carbon nanotubes via inhalation or through injection into the abdominal cavity develop severe inflammation. This and the tissue changes (fibrosis) that exposure causes lead to impaired lung function and perhaps even to cancer. For example, a year or two ago, alarming reports by other scientists suggested that carbon nanotubes are very similar to asbestos fibres, which are themselves biopersistent and which can cause lung cancer (mesothelioma) in humans a considerable time after exposure.

This current study thus represents a breakthrough in nanotechnology and nanotoxicology, since it clearly shows that endogenous MPO can break down carbon nanotubes. This enzyme is expressed in certain types of white blood cell (neutrophils), which use it to neutralise harmful bacteria. Now, however, the researchers have found that the enzyme also works on carbon nanotubes, breaking them down into water and carbon dioxide. The researchers also showed that carbon nanotubes that have been broken down by MPO no longer give rise to inflammation in mice.

“This means that there might be a way to render carbon nanotubes harmless, for example in the event of an accident at a production plant,” says Dr Fadeel. “But the findings are also relevant to the future use of carbon nanotubes for medical purposes.”

The study was led by researchers at Karolinska Institutet, the University of Pittsburgh and the National Institute for Occupational Safety and Health (NIOSH), and was financed in part through grants from the National Institutes of Health (NIH) and the Seventh Framework Programme of the European Commission. The work was conducted as part of the NANOMMUNE project, which is coordinated by associate professor Bengt Fadeel of the Institute of Environmental Medicine, Karolinska Institutet, and which comprises a total of thirteen research groups in Europe and the USA.

December 2, 2009

More stem cell lines open for research

Very welcome news and finally a tangible shift away from the idiotic christianist policies of the Bush 43 administration. This is an area of medical research where the United States should be world leaders, not playing catch up after eight years of a completely medieval stance toward science and medicine.

From the link:

The National Institutes of Health said Wednesday that it had approved 13 new human embryonic stem cell lines for use by federally financed researchers, with another 96 lines under review.

The action followed President Obama’s decision in March to expand the number of such cell lines beyond those available under a policy set by President George W. Bush, which permitted research to begin only with lines already available on Aug. 9, 2001.

Since that date, biomedical researchers supported by the N.I.H. have had to raise private money to derive the cells, which are obtained from the fertilized embryos left over from in vitro fertility clinics.

With federal money banned from being used in any part of the work on the derived lines, researchers had to divide their laboratories and go to extreme lengths to separate research materials based on the financing source.

“You can imagine what it meant not to be able to carry a pipette from one room to another,” said Ali H. Brivanlou, a researcher at Rockefeller University. “They even had to repaint the walls to ensure no contamination by federal funds.”

November 18, 2009

The stimulus package and science

Scientific research wasn’t left out of this year’s stimulus plan to the tune of $21 billion, and a federal website tracks all that stimulus.

From the link:

The stimulus plan passed by the US Congress earlier this year provided $21 billion for scientific R&D to be allocated through the National Institutes of Health, the Department of Energy, and other agencies. (The full text of the bill is available in this large pdf file.) The debate still rages amongst politicians and economists about just how many jobs the $787 billion bill has created. In the meantime, the government has launched an interesting website detailing where that scientific R&D money went.

Call it propaganda–the site is called ScienceWorksForUS–but it’s interesting to browse through the detailed list and see which research projects were funded and for how much.

June 4, 2009

Photon driven nanomotor

Fair warning to all readers, a major press release dump is coming. Mostly nanotechnology news.

First up is research on a molecular nanomotor driven by light.

The release:

New, light-driven nanomotor is simpler, more promising, scientists say

GAINESVILLE, Fla. — Sunflowers track the sun as it moves from east to west. But people usually have to convert sunlight into electricity or heat to put its power to use.

Now, a team of University of Florida chemists is the latest to report a new mechanism to transform light straight into motion – albeit at a very, very, very tiny scale.

In a paper expected to appear soon in the online edition of the journal Nano Letters, the UF team reports building a new type of “molecular nanomotor” driven only by photons, or particles of light. While it is not the first photon-driven nanomotor, the almost infinitesimal device is the first built entirely with a single molecule of DNA — giving it a simplicity that increases its potential for development, manufacture and real-world applications in areas ranging from medicine to manufacturing, the scientists say.

“It is easy to assemble, has fewer parts and theoretically should be more efficient,” said Huaizhi Kang, a doctoral student in chemistry at UF and the first author of the paper.

The scale of the nanomotor is almost vanishingly small.

In its clasped, or closed, form, the nanomotor measures 2 to 5 nanometers — 2 to 5 billionths of a meter. In its unclasped form, it extends as long as 10 to 12 nanometers. Although the scientists say their calculations show it uses considerably more of the energy in light than traditional solar cells, the amount of force it exerts is proportional to its small size.

But that won’t necessarily limit its potential.

In coming years, the nanomotor could become a component of microscopic devices that repair individual cells or fight viruses or bacteria. Although in the conceptual stage, those devices, like much larger ones, will require a power source to function. Because it is made of DNA, the nanomotor is biocompatible. Unlike traditional energy systems, the nanomotor also produces no waste when it converts light energy into motion.

“Preparation of DNA molecules is relatively easy and reproducible, and the material is very safe,” said Yan Chen, a UF chemistry doctoral student and one of the authors of the paper.

Applications in the larger world are more distant. Powering a vehicle, running an assembly line or otherwise replacing traditional electricity or fossil fuels would require untold trillions of nanomotors, all working together in tandem — a difficult challenge by any measure.

“The major difficulty lies ahead,” said Weihong Tan, a UF professor of chemistry and physiology, author of the paper and the leader of the research group reporting the findings. “That is how to collect the molecular level force into a coherent accumulated force that can do real work when the motor absorbs sunlight.”

Tan added that the group has already begun working on the problem.

“Some prototype DNA nanostructures incorporating single photo-switchable motors are in the making which will synchronize molecular motions to accumulate forces,” he said.

To make the nanomotor, the researchers combined a DNA molecule they created in the lab with azobenzene, a chemical compound that responds to light. A high-energy photon prompts one response; lower energy another.

To demonstrate the movement, the researchers attached a fluorophore, or light-emitter, to one end of the nanomotor and a quencher, which can quench the emitting light, to the other end. Their instruments recorded emitted light intensity that corresponded to the motor movement.

“Radiation does cause things to move from the spinning of radiometer wheels to the turning of sunflowers and other plants toward the sun,” said Richard Zare, distinguished professor and chairman of chemistry at Stanford University. “What Professor Tan and co-workers have done is to create a clever light-actuated nanomotor involving a single DNA molecule. I believe it is the first of its type.”

 

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The National Institutes of Health and the National Science Foundation funded the research. The other coauthors of this paper are Haipeng Liu, Joseph A. Phillips, Zehui Cao, Youngmi Kim, Zunyi Yang and Jianwei Li.

April 28, 2009

Nanoneedles

Nanotech with a lot of likely bioscience and medical applications.

The release:

Nanoneedle is small in size, but huge in applications

CHAMPAIGN, Ill. — Researchers at the University of Illinois have developed a membrane-penetrating nanoneedle for the targeted delivery of one or more molecules into the cytoplasm or the nucleus of living cells. In addition to ferrying tiny amounts of cargo, the nanoneedle can also be used as an electrochemical probe and as an optical biosensor.

“Nanoneedle-based delivery is a powerful new tool for studying biological processes and biophysical properties at the molecular level inside living cells,” said

Min-Feng Yu, a professor of mechanical science and engineering and corresponding author of a paper accepted for publication in Nano Letters, and posted on the journal’s Web site.

In the paper, Yu and collaborators describe how they deliver, detect and track individual fluorescent quantum dots in a cell’s cytoplasm and nucleus. The quantum dots can be used for studying molecular mechanics and physical properties inside cells.

To create a nanoneedle, the researchers begin with a rigid but resilient boron-nitride nanotube. The nanotube is then attached to one end of a glass pipette for easy handling, and coated with a thin layer of gold. Molecular cargo is then attached to the gold surface via “linker” molecules. When placed in a cell’s cytoplasm or nucleus, the bonds with the linker molecules break, freeing the cargo.

With a diameter of approximately 50 nanometers, the nanoneedle introduces minimal intrusiveness in penetrating cell membranes and accessing the interiors of live cells.

The delivery process can be precisely controlled, monitored and recorded – goals that have not been achieved in prior studies.

“The nanoneedle provides a mechanism by which we can quantitatively examine biological processes occurring within a cell’s nucleus or cytoplasm,” said Yang Xiang, a professor of molecular and integrative physiology and a co-author of the paper. “By studying how individual proteins and molecules of DNA or RNA mobilize, we can better understand how the system functions as a whole.”

The ability to deliver a small number of molecules or nanoparticles into living cells with spatial and temporal precision may make feasible numerous new strategies for biological studies at the single-molecule level, which would otherwise be technically challenging or even impossible, the researchers report.

“Combined with molecular targeting strategies using quantum dots and magnetic nanoparticles as molecular probes, the nanoneedle delivery method can potentially enable the simultaneous observation and manipulation of individual molecules,” said Ning Wang, a professor of mechanical science and engineering and a co-author of the paper.

Beyond delivery, the nanoneedle-based approach can also be extended in many ways for single-cell studies, said Yu, who also is a researcher at the Center for Nanoscale Chemical-Electrical-Mechanical Manufacturing Systems. “Nanoneedles can be used as electrochemical probes and as optical biosensors to study cellular environments, stimulate certain types of biological sequences, and examine the effect of nanoparticles on cellular physiology.”

 

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With Wang, Xiang and Yu, co-authors of the paper are graduate student Kyungsuk Yum and postdoctoral research associate Sungsoo Na. Yu and Wang are affiliated with the university’s Beckman Institute. Wang is also affiliated with the department of bioengineering and with the university’s Micro and Nanotechnology Laboratory.

The Grainger Foundation, National Science Foundation and National Institutes of Health funded the work.

March 27, 2009

Nanogenerators

Very cool nanotech. Not sure how close this is to market, but man it’s very cool.

The release:

New nanogenerator may charge iPods and cell phones with a wave of the hand

IMAGE: Pictured is a schematic illustration shows the microfiber-nanowire hybrid nanogenerator, which is the basis of using fabrics for generating electricity.

Click here for more information. 

SALT LAKE CITY, March 26, 2009 — Imagine if all you had to do to charge your iPod or your BlackBerry was to wave your hand, or stretch your arm, or take a walk? You could say goodbye to batteries and never have to plug those devices into a power source again.

In research presented here today at the American Chemical Society’s 237th National Meeting, scientists from Georgia describe technology that converts mechanical energy from body movements or even the flow of blood in the body into electric energy that can be used to power a broad range of electronic devices without using batteries.

“This research will have a major impact on defense technology, environmental monitoring, biomedical sciences and even personal electronics,” says lead researcher Zhong Lin Wang, Regents’ Professor, School of Material Science and Engineering at the Georgia Institute of Technology. The new “nanogenerator” could have countless applications, among them a way to run electronic devices used by the military when troops are far in the field.

The researchers describe harvesting energy from the environment by converting low-frequency vibrations, like simple body movements, the beating of the heart or movement of the wind, into electricity, using zinc oxide (ZnO) nanowires that conduct the electricity. The ZnO nanowires are piezoelectric — they generate an electric current when subjected to mechanical stress. The diameter and length of the wire are 1/5,000th and 1/25th the diameter of a human hair.

In generating energy from movement, Wang says his team concluded that it was most effective to develop a method that worked at low frequencies and was based on flexible materials. The ZnO nanowires met these requirements. At the same time, he says a real advantage of this technology is that the nanowires can be grown easily on a wide variety of surfaces, and the nanogenerators will operate in the air or in liquids once properly packaged. Among the surfaces on which the nanowires can be grown are metals, ceramics, polymers, clothing and even tents.

“Quite simply, this technology can be used to generate energy under any circumstances as long as there is movement,” according to Wang.

To date, he says that there have been limited methods created to produce nanopower despite the growing need by the military and defense agencies for nanoscale sensing devices used to detect bioterror agents. The nanogenerator would be particularly critical to troops in the field, where they are far from energy sources and need to use sensors or communication devices. In addition, having a sensor which doesn’t need batteries could be extremely useful to the military and police sampling air for potential bioterrorism attacks in the United States, Wang says.

While biosensors have been miniaturized and can be implanted under the skin, he points out that these devices still require batteries, and the new nanogenerator would offer much more flexibility.

A major advantage of this new technology is that many nanogenerators can produce electricity continuously and simultaneously. On the other hand, the greatest challenge in developing these nanogenerators is to improve the output voltage and power, he says.

Last year Wang’s group presented a study on nanogenerators driven by ultrasound. Today’s research represents a much broader application of nanogenerators as driven by low-frequency body movement.

 

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The study was funded by the Defense Advanced Research Projects Agency, the Department of Energy, the National Institutes of Health and the National Science Foundation.

The American Chemical Society is a nonprofit organization chartered by the U.S. Congress. With more than 154,000 members, ACS is the world’s largest scientific society and a global leader in providing access to chemistry-related research through its multiple databases, peer-reviewed journals and scientific conferences. Its main offices are in Washington, D.C., and Columbus, Ohio.

 

February 15, 2009

Nanoparticle toxicity? Not so much

Anyone who’s read this blog for any length of time knows I’m a sucker for nanotech news. This comes from the 2009 AAAS Annual Meeting.

The release:

Nanoparticle toxicity doesn’t get wacky at the smallest sizes

Big and small nanoparticles affect most genes similarly

CHICAGO — The smallest nano-sized silica particles used in biomedicine and engineering likely won’t cause unexpected biological responses due to their size, according to work presented today. The result should allay fears that cells and tissues will react unpredictably when exposed to the finest silica nanomaterials in industrial or commercial applications.

Nanotoxicologist Brian Thrall and colleagues found that, mostly, size doesn’t matter, by using total surface area as a measure of dose, rather than particle mass or number of particles, and observing how cultured cells responded biologically.

“If you consider surface area as the dose metric, then you get similar types of responses independent of the size of the particle,” said Thrall, a scientist at the Department of Energy’s Pacific Northwest National Laboratory in Richland, Wash. “That suggests the chemistry that drives the biological responses doesn’t change when you get down to the smallest nanoparticle.”

Nanoparticles are materials made up of spherical particles that are on average 100 to 1,000 times smaller than the width of a human hair. They are being used in tires, biomedical research, and cosmetics. Researchers are exploring these tiny spheres because their physical and chemical properties at that size offer advantages that standard materials don’t, such as being able to float through blood vessels to deliver drugs.

But whether these materials are safe for human consumption is not yet clear. Previous work suggested in some cases, nanoparticles become more toxic to cells the smaller the particles get.

Thrall presented this toxicology data on amorphous silica nanoparticles today at the 2009 American Association for the Advancement of Science’s annual meeting. He also presented data on which cellular proteins the nanoparticles use to get inside cells.

One difficulty in measuring toxicity is that not everyone agrees which kind of dose unit to compare. Some researchers measure the dose by total weight, some by the number of particles. Neither method distinguishes whether a nanomaterial’s toxicity is due to the inherent nature of the material or the particle size under scrutiny.

“Different dose metrics give different impressions of which particles are more toxic,” he said.

To find out, Thrall and his colleagues at PNNL measured the dose at which the particles caused a biological response. The biological response was either death of the cell, or a change in which genes the cell turned on and off. They found that when calculating doses by particle number or mass, the amount needed to generate a biological response was all over the map.

They found that the best way to pinpoint how toxic the particles are to cells was to calculate the dose based on the total surface area of the nanomaterial. Only when they considered the surface area of the dose could they predict the biological response.

And the biological response, they found, was very similar regardless of the size of the nanoparticles. Inside cells, some genes responded to nanoparticles by ramping up or down. More than 76 percent of these genes behaved the same for all nanoparticle sizes tested. This indicated to the researchers that, for these genes, the nanoparticles didn’t pick up weird chemical properties as they shrunk in size.

“The big fear is that you’d see unique biological pathways being affected when you get down to the nanoscale. For the most part, we didn’t see that,” said Thrall.

However, the team found some genes for which size did matter. A handful of genes, these fell into two categories: smaller particles appeared to affect genes that might be involved in inflammation. The larger particles appeared to affect genes that transport positively charged atoms into cells. This latter result could be due to metals contaminating the preparation of the larger particles, Thrall suggested.

Overall, the results contribute to a better understanding of what goes on at the nanoscale.

 

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Reference: Brian Thrall, Systems Toxicology of Engineered Nanomaterials in seminar titled Driving Beyond Our Nano-Headlights? Saturday, February 14, 8:30 am – 11:30 am in conference room Hyatt Regency, Crystal Ballroom B, at the American Association for the Advancement of Science 2009 Annual Meeting, Chicago, Ill.

This work was supported by Laboratory-Directed Research and Development and then the National Institutes of Health.

Pacific Northwest National Laboratory is a Department of Energy Office of Science national laboratory where interdisciplinary teams advance science and technology and deliver solutions to America’s most intractable problems in energy, national security and the environment. PNNL employs 4,200 staff and has an $850 million annual budget. Ohio-based Battelle has managed PNNL since the lab’s inception in 1965.

http://www.pnl.gov/aaas/

November 6, 2008

Gold nanostars

Very cool, and looks to have some great applications.

The release:

Gold nanostar shape of the future

DURHAM, N.C. – Rods, cones, cubes and spheres – move aside. Tiny gold stars, smaller than a billionth of a meter, may hold the promise for new approaches to medical diagnoses or testing for environmental contaminants.

While nanoparticles have been the rage across a wide spectrum of sciences, a new study by Duke University bioengineers indicates that of all the shapes studied to date, stars may shine above all the rest for certain applications.

The key is light, and how that light reflects off the particles. Compared to the other shapes, nanostars can dramatically enhance the reflected light, the Duke scientists found. This increases their potential usefulness as a tracer, label, or contrast agent.

Since the researchers also found that the size and shape of the nanostars affect the spectrum of reflected light, they believe that these tiny nanostars can also be “tuned” to identify particular molecules or chemicals.

“To our knowledge, this is the first report of the development and use of gold nanostars as labels for molecular detection and description of their controlled synthesis with different sizes and shapes” said Chris Khoury, lead author of a paper published on-line in the Journal of Physical Chemistry. Khoury is a graduate student in biomedical engineering working in the laboratory of senior researcher Tuan Vo-Dinh, R. Eugene and Susie E. Goodson Distinguished Professor of Biomedical Engineering and director of The Fitzpatrick Institute for Photonics at Duke.

In the Duke experiments, the nanostars were used in conjunction with a phenomena first described in the 1970s known as surface-enhanced Raman scattering (SERS). When light, usually from a laser, is shined on a sample, the target molecule vibrates and scatters back in its own unique light, often referred to as the Raman scatter. However, this Raman response is extremely weak. When the target molecule is coupled with a metal nanoparticle or nanostructure, the Raman response is greatly enhanced by the SERS effect –often by more than a million times, Vo-Dinh said.

In the early 1980s, while at the Oak Ridge National Laboratory, Tenn., Vo-Dinh and colleagues were among the first to demonstrate that SERS could be put into practical use to detect chemicals including carcinogens, environmental pollutants, and early markers of disease. Now at Duke, Vo-Dinh is pushing the boundaries of the SERS technology by designing a variety of unique types and shapes of metal nanoparticles that can be used as SERS labels for chemical and biomedical detection.

“We are trying to understand which type of nanostructures will give us the optimal signal so we can use them to monitor trace amounts of pollutants or detect diseases in their earliest stage” Vo-Dinh said. “This study is the first demonstration that these nanostars can enhance the effect of SERS to produce strong and unique signatures, like ‘optical fingerprints.'”

Khoury “grew” the nanostars by mixing miniscule gold particle seeds in a growth solution. As more gold was added to the solution, protrusions began to sprout from the central core. Additional gold increased the size of the entire particle.

“These experiments demonstrate that it is possible to vary the size and shape of the nanostars in a controlled fashion by adjusting the volume of gold seeds added to the growth solution,” Khoury said. “We found that variations in star size changed the reflected light, which hints toward the tuning capabilities that can be exploited by SERS technology.”

For such studies, or those involving environmental contaminants, a dye would be attached to the nanostars and mixed with the sample to be tested. The sample would then be placed under a microscope and hit with a burst of laser energy. Sensors would pick up the Raman scattering and interpret the unique optical fingerprint.

Khoury said that nanostars are small enough to pass through cell walls into the interior of the cell, which would make them an effective method for molecular diagnostics. Nanostars could be attached to an antibody to search for antigens, or coupled with a dye to improve the effectiveness of different imaging tests.

While silver enhances the Raman scattering more effectively, gold was chosen as the metallic base of the current nanoparticle because it is a stable metal that doesn’t cause immune system reactions within the body. Unlike silver, it also does not oxidize in samples.

Vo-Dinh research group at Duke is currently developing novel techniques for chemical detection and medical diagnostics using SERS. Vo-Dinh said that since each SERS label molecule has its own unique optical fingerprint, theoretically a single probe could be created that could detect an array of different cancers, for example, or different environmental toxins.

 

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The research was supported by the National Institutes of Health.

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