Shaken, not stirred: Scientists spy molecular maneuvers

ScienceDaily (Oct. 27, 2011) — Stir this clear liquid in a glass vial and nothing happens. Shake this liquid, and free-floating sheets of protein-like structures emerge, ready to detect molecules or catalyze a reaction. This isn't the latest gadget from James Bond's arsenal -- rather, the latest research from the U. S. Department of Energy (DOE)'s Lawrence Berkeley National Laboratory (Berkeley Lab) scientists unveiling how slim sheets of protein-like structures self-assemble. This "shaken, not stirred" mechanism provides a way to scale up production of these two-dimensional nanosheets for a wide range of applications, such as platforms for sensing, filtration and templating growth of other nanostructures.

"Our findings tell us how to engineer two-dimensional, biomimetic materials with atomic precision in water," said Ron Zuckermann, Director of the Biological Nanostructures Facility at the Molecular Foundry, a DOE nanoscience user facility at Berkeley Lab. "What's more, we can produce these materials for specific applications, such as a platform for sensing molecules or a membrane for filtration."

Zuckermann, who is also a senior scientist at Berkeley Lab, is a pioneer in the development of peptoids, synthetic polymers that behave like naturally occurring proteins without degrading. His group previously discovered peptoids capable of self-assembling into nanoscale ropes, sheets and jaws, accelerating mineral growth and serving as a platform for detecting misfolded proteins.

In this latest study, the team employed a Langmuir-Blodgett trough -- a bath of water with Teflon-coated paddles at either end -- to study how peptoid nanosheets assemble at the surface of the bath, called the air-water interface. By compressing a single layer of peptoid molecules on the surface of water with these paddles, said Babak Sanii, a post-doctoral researcher working with Zuckermann, "we can squeeze this layer to a critical pressure and watch it collapse into a sheet."

"Knowing the mechanism of sheet formation gives us a set of design rules for making these nanomaterials on a much larger scale," added Sanii.

To study how shaking affected sheet formation, the team developed a new device called the SheetRocker to gently rock a vial of peptoids from upright to horizontal and back again. This carefully controlled motion allowed the team to precisely control the process of compression on the air-water interface.

"During shaking, the monolayer of peptoids essentially compresses, pushing chains of peptoids together and squeezing them out into a nanosheet. The air-water interface essentially acts as a catalyst for producing nanosheets in 95% yield," added Zuckermann. "What's more, this process may be general for a wide variety of two-dimensional nanomaterials."

This research is reported in a paper titled, "Shaken, not stirred: Collapsing a peptoid monolayer to produce free-floating, stable nanosheets," appearing in the Journal of the American Chemical Society (JACS) and available in JACS online. Co-authoring the paper with Zuckermann and Sanii were Romas Kudirka, Andrew Cho, Neeraja Venkateswaran, Gloria Olivier, Alexander Olson, Helen Tran, Marika Harada and Li Tan.

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

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Journal Reference:

Babak Sanii, Romas Kudirka, Andrew Cho, Neeraja Venkateswaran, Gloria K. Olivier, Alexander M. Olson, Helen Tran, R. Marika Harada, Li Tan, Ronald N. Zuckermann. Shaken, Not Stirred: Collapsing a Peptoid Monolayer To Produce Free-Floating, Stable Nanosheets. Journal of the American Chemical Society, 2011; : 111012114427004 DOI: 10.1021/ja206199d

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Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.

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Shaken, not stirred: Scientists spy molecular maneuvers

ScienceDaily (Oct. 27, 2011) — Stir this clear liquid in a glass vial and nothing happens. Shake this liquid, and free-floating sheets of protein-like structures emerge, ready to detect molecules or catalyze a reaction. This isn't the latest gadget from James Bond's arsenal -- rather, the latest research from the U. S. Department of Energy (DOE)'s Lawrence Berkeley National Laboratory (Berkeley Lab) scientists unveiling how slim sheets of protein-like structures self-assemble. This "shaken, not stirred" mechanism provides a way to scale up production of these two-dimensional nanosheets for a wide range of applications, such as platforms for sensing, filtration and templating growth of other nanostructures.

"Our findings tell us how to engineer two-dimensional, biomimetic materials with atomic precision in water," said Ron Zuckermann, Director of the Biological Nanostructures Facility at the Molecular Foundry, a DOE nanoscience user facility at Berkeley Lab. "What's more, we can produce these materials for specific applications, such as a platform for sensing molecules or a membrane for filtration."

Zuckermann, who is also a senior scientist at Berkeley Lab, is a pioneer in the development of peptoids, synthetic polymers that behave like naturally occurring proteins without degrading. His group previously discovered peptoids capable of self-assembling into nanoscale ropes, sheets and jaws, accelerating mineral growth and serving as a platform for detecting misfolded proteins.

In this latest study, the team employed a Langmuir-Blodgett trough -- a bath of water with Teflon-coated paddles at either end -- to study how peptoid nanosheets assemble at the surface of the bath, called the air-water interface. By compressing a single layer of peptoid molecules on the surface of water with these paddles, said Babak Sanii, a post-doctoral researcher working with Zuckermann, "we can squeeze this layer to a critical pressure and watch it collapse into a sheet."

"Knowing the mechanism of sheet formation gives us a set of design rules for making these nanomaterials on a much larger scale," added Sanii.

To study how shaking affected sheet formation, the team developed a new device called the SheetRocker to gently rock a vial of peptoids from upright to horizontal and back again. This carefully controlled motion allowed the team to precisely control the process of compression on the air-water interface.

"During shaking, the monolayer of peptoids essentially compresses, pushing chains of peptoids together and squeezing them out into a nanosheet. The air-water interface essentially acts as a catalyst for producing nanosheets in 95% yield," added Zuckermann. "What's more, this process may be general for a wide variety of two-dimensional nanomaterials."

This research is reported in a paper titled, "Shaken, not stirred: Collapsing a peptoid monolayer to produce free-floating, stable nanosheets," appearing in the Journal of the American Chemical Society (JACS) and available in JACS online. Co-authoring the paper with Zuckermann and Sanii were Romas Kudirka, Andrew Cho, Neeraja Venkateswaran, Gloria Olivier, Alexander Olson, Helen Tran, Marika Harada and Li Tan.

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

Recommend this story on Facebook, Twitter,
and Google +1:

Other bookmarking and sharing tools:

Story Source:

The above story is reprinted from materials provided by DOE/Lawrence Berkeley National Laboratory.

Note: Materials may be edited for content and length. For further information, please contact the source cited above.

Journal Reference:

Babak Sanii, Romas Kudirka, Andrew Cho, Neeraja Venkateswaran, Gloria K. Olivier, Alexander M. Olson, Helen Tran, R. Marika Harada, Li Tan, Ronald N. Zuckermann. Shaken, Not Stirred: Collapsing a Peptoid Monolayer To Produce Free-Floating, Stable Nanosheets. Journal of the American Chemical Society, 2011; : 111012114427004 DOI: 10.1021/ja206199d

Note: If no author is given, the source is cited instead.

Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.

View the original article here

'Critical baby step' taken for spying life on a molecular scale

ScienceDaily (May 18, 2011) — The ability to image single biological molecules in a living cell is something that has long eluded researchers; however, a novel technique, using the structure of diamond, may well be able to do this and potentially provide a tool for diagnosing, and eventually developing a treatment for, hard-to-cure diseases such as cancer.

In a study published May 19 in the Institute of Physics and the German Physical Society's New Journal of Physics, researchers have developed a technique, exploiting a specific defect in the lattice structure of diamond, to externally detect the spins of individual molecules.

Magnetic Resonance Imaging (MRI) has already taken advantage of a molecule's spin to give clear snapshots of organs and tissue within the human body, however to get a more detailed insight into the workings of disease, the imaging scale must be brought down to individual biomolecules, and captured whilst the cells are still alive.

Co-lead author Professor Phillip Hemmer, Electrical & Computer Engineering, Texas A&M University, said, "Many conditions, such as cancer and aging, have their roots at the molecular scale. Therefore if we could somehow develop a tool that would allow us to do magnetic resonance imaging of individual biomolecules in a living cell then we would have a powerful new tool for diagnosing and eventually developing cures for such stubborn diseases."

To do this, the researchers, from Professor Joerg Wrachtrup's group at the University of Stuttgart and Texas A&M University, used a constructed defect in the structure of diamond called a nitrogen vacancy (NV) -- a position within the lattice structure where one of the carbon atoms is replaced with a nitrogen atom.

Instead of bonding to four other carbon atoms, the nitrogen atom only bonds to three carbon atoms leaving a spare pair of electrons, acting as one of the strongest magnets on an atomic scale.

The most important characteristic of a diamond NV is that it has an optical readout -- it emits bright red light when excited by a laser, which is dependent on which way the magnet is pointing.

The researchers found that if an external spin is placed close to the NV it will cause the magnet to point in a different direction, therefore changing the amount of light emitted by it.

This change of light can be used to gauge which way the external molecule is spinning and therefore create a one-dimensional image of the external spin. If combined with additional knowledge of the surface, or a second NV nearby, a more detailed image with additional dimensions could be had.

To test this theory, nitrogen was implanted into a sample of diamond in order to produce the necessary NVs. External molecules were brought to the surface of the diamond, using several chemical interactions, for their spins to be analyzed.

Spins that exist within the diamond structure itself have already been modelled, so to test that the spins were indeed external, the researchers chemically cleaned the diamond surface and performed the analysis again to prove that the spins had been washed away.

Professor Hemmer continued, "Currently, biological interactions are deduced mostly by looking at large ensembles. In this case you are looking only at statistical averages and details of the interaction which are not always clear. Often the data is taken after killing the cell and spreading its contents onto a gene chip, so it is like looking at snapshots in time when you really want to see the whole movie."

"Clearly there is much work to be done before we can, if ever, reach our long-term goal of spying on the inner workings of life on the molecular scale. But we have to learn to walk before we can run, and this breakthrough represents one of the first critical baby steps."

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by Institute of Physics, via EurekAlert!, a service of AAAS.

Journal Reference:

Grotz et al. Sensing external spins with NV diamond. New Journal of Physics, 2011; [link]

Note: If no author is given, the source is cited instead.

Disclaimer: This article is not intended to provide medical advice, diagnosis or treatment. Views expressed here do not necessarily reflect those of ScienceDaily or its staff.

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Doppler effect found even at molecular level -- 169 years after its discovery

ScienceDaily (May 11, 2011) — Whether they know it or not, anyone who's ever gotten a speeding ticket after zooming by a radar gun has experienced the Doppler effect -- a measurable shift in the frequency of radiation based on the motion of an object, which in this case is your car doing 45 miles an hour in a 30-mph zone.

But for the first time, scientists have experimentally shown a different version of the Doppler effect at a much, much smaller level -- the rotation of an individual molecule. Prior to this such an effect had been theorized, but it took a complex experiment with a synchrotron to prove it's for real.

"Some of us thought of this some time ago, but it's very difficult to show experimentally," said T. Darrah Thomas, a professor emeritus of chemistry at Oregon State University and part of an international research team that just announced its findings in Physical Review Letters, a professional journal.

Most illustrations of the Doppler effect are called "translational," meaning the change in frequency of light or sound when one object moves away from the other in a straight line, like a car passing a radar gun. The basic concept has been understood since an Austrian physicist named Christian Doppler first proposed it in 1842.

But a similar effect can be observed when something rotates as well, scientists say.

"There is plenty of evidence of the rotational Doppler effect in large bodies, such as a spinning planet or galaxy," Thomas said. "When a planet rotates, the light coming from it shifts to higher frequency on the side spinning toward you and a lower frequency on the side spinning away from you. But this same basic force is at work even on the molecular level."

In astrophysics, this rotational Doppler effect has been used to determine the rotational velocity of things such as planets. But in the new study, scientists from Japan, Sweden, France and the United States provided the first experimental proof that the same thing happens even with molecules.

At this tiny level, they found, the rotational Doppler effect can be even more important than the linear motion of the molecules, the study showed.

The findings are expected to have application in a better understanding of molecular spectroscopy, in which the radiation emitted from molecules is used to study their makeup and chemical properties. It is also relevant to the study of high energy electrons, Thomas said.

"There are some studies where a better understanding of this rotational Doppler effect will be important," Thomas said. "Mostly it's just interesting. We've known about the Doppler effect for a very long time but until now have never been able to see the rotational Doppler effect in molecules."

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by Oregon State University, via EurekAlert!, a service of AAAS.

Journal Reference:

T. D. Thomas, E. Kukk, K. Ueda, T. Ouchi, K. Sakai, T. X. Carroll, C. Nicolas, O. Travnikova, and C. Miron. Experimental observation of rotational Doppler broadening in a molecular system. Physical Review Letters, Accepted Apr 12, 2011

Note: If no author is given, the source is cited instead.

Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.

View the original article here

Doppler effect found even at molecular level -- 169 years after its discovery

ScienceDaily (May 11, 2011) — Whether they know it or not, anyone who's ever gotten a speeding ticket after zooming by a radar gun has experienced the Doppler effect -- a measurable shift in the frequency of radiation based on the motion of an object, which in this case is your car doing 45 miles an hour in a 30-mph zone.

But for the first time, scientists have experimentally shown a different version of the Doppler effect at a much, much smaller level -- the rotation of an individual molecule. Prior to this such an effect had been theorized, but it took a complex experiment with a synchrotron to prove it's for real.

"Some of us thought of this some time ago, but it's very difficult to show experimentally," said T. Darrah Thomas, a professor emeritus of chemistry at Oregon State University and part of an international research team that just announced its findings in Physical Review Letters, a professional journal.

Most illustrations of the Doppler effect are called "translational," meaning the change in frequency of light or sound when one object moves away from the other in a straight line, like a car passing a radar gun. The basic concept has been understood since an Austrian physicist named Christian Doppler first proposed it in 1842.

But a similar effect can be observed when something rotates as well, scientists say.

"There is plenty of evidence of the rotational Doppler effect in large bodies, such as a spinning planet or galaxy," Thomas said. "When a planet rotates, the light coming from it shifts to higher frequency on the side spinning toward you and a lower frequency on the side spinning away from you. But this same basic force is at work even on the molecular level."

In astrophysics, this rotational Doppler effect has been used to determine the rotational velocity of things such as planets. But in the new study, scientists from Japan, Sweden, France and the United States provided the first experimental proof that the same thing happens even with molecules.

At this tiny level, they found, the rotational Doppler effect can be even more important than the linear motion of the molecules, the study showed.

The findings are expected to have application in a better understanding of molecular spectroscopy, in which the radiation emitted from molecules is used to study their makeup and chemical properties. It is also relevant to the study of high energy electrons, Thomas said.

"There are some studies where a better understanding of this rotational Doppler effect will be important," Thomas said. "Mostly it's just interesting. We've known about the Doppler effect for a very long time but until now have never been able to see the rotational Doppler effect in molecules."

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by Oregon State University, via EurekAlert!, a service of AAAS.

Journal Reference:

T. D. Thomas, E. Kukk, K. Ueda, T. Ouchi, K. Sakai, T. X. Carroll, C. Nicolas, O. Travnikova, and C. Miron. Experimental observation of rotational Doppler broadening in a molecular system. Physical Review Letters, Accepted Apr 12, 2011

Note: If no author is given, the source is cited instead.

Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.

View the original article here