Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Next generation nanofilms created

15.04.2009
With the human genome in hand, biochemists have cataloged the 3-D structures of thousands of proteins isolated from living cells.

But one important class of proteins -- those stuck in the cell membranes -- has proven difficult to extract and study in 3-D crystals. Now an international team of scientists has developed a way to train such molecules to line up neatly on the surface of water in thin, tissue-like layers called nanofilms.

This technique should allow biochemists to better see and study the molecules and may lead to a new generation of molecular electronics and ultra-thin materials only one molecule thick.

"To the best of our knowledge, this is the first time aligned films less than a nanometer thick have been produced," say Iftach Nevo, a Marie Curie fellow at the University of Aarhus in Denmark, and Leslie Leiserowitz of the Weizmann Institute of Science in Israel. Together with their colleagues at these institutions and at the Max-Planck Institute of Colloids and Interfaces in Germany and Northwestern University in Evanston, they describe their research in the 14 April 2009 issue of The Journal of Chemical Physics, published by the American Institute of Physics.

One way of creating a nanofilm is to build it on the surface of water. First, the building blocks of the film are dissolved in a volatile substance. When a drop of this solution is splashed onto water, the solvent evaporates. The building blocks left floating on the water interact with each other and spontaneously come together -- like soap scum in a bathtub -- to create a thin crystalline layer.

The shortcoming of this technique is that the thin crystals in the film created will be a mess. Like a mob in a dance club, molecules floating on a surface tend to spin around chaotically with little regard for order. Different patches of molecules will point different, random directions. Because the orientation of these molecules dictates the electrical, magnetic, and optical properties of the final film, these jumbled regions are difficult to develop into useful technologies. They are also difficult to analyze using imaging techniques like X-ray diffraction.

To force the molecules to line up, the team blasted them with nanosecond laser pulses. These pulses create an electric field that interacts with the molecules, rotating them slowly. The electric field associated with these laser pulses is polarized, filtered so that all of the light waves vibrate in the same direction. Molecules caught in the laser feel most stable when they line up along this direction, a process analogous to the needle in a compass swinging to line up with the Earth's magnetic field. Eventually, this forms an aligned film with long range order.

The technique has not been completely perfected yet. Its success rate is about 30 percent, but the group believes that a better understanding of what is happening during the evaporation process and how the molecules interact with each other just before solidifying into a film will improve the efficiency.

When these molecules line up in a stable 2-D layer, their structures can be seen with X-ray imaging techniques normally used on 3-D crystals. "Alignment should enhance the X-ray diffraction intensity by more than two orders of magnitude allowing more detailed structure elucidations," say Nevo and Leiserowitz. The technique could be useful for studying molecules that cannot be easily crystallized in three dimensions -- cell membrane proteins are only one example.

It could also be useful for creating 3-D crystals with aligned structures. The 2-D layer can be used to seed the growth of these crystals, providing a stage on which this growth can be monitored using X-ray diffraction.

Another application is molecular electronics, like field-effect transistors, that require ordered molecules. Also interesting is an emerging class of solar cell technologies that are trying to copy nature by reverse-engineering photosynthesis. The ability to align the molecules in these devices will be important to their effectiveness, explains team member Tamar Seideman of Northwestern University.

Because the technique should work with a variety of molecules, it may pave the way for brand new kinds of self-assembling nanomaterials. "The international team that produced this paper is outstanding, and this is one of those papers that will likely spawn a number of novel applications that haven't been discovered yet," says Edward Castner of Rutgers University, Associate Editor for The Journal of Chemical Physics.

The article "Laser-Induced Self Assembly on Water Surfaces" by Iftach Nevo et al will be published online on April 14, 2009. Journalists can obtain a free copy by emailing dpowell@aip.org.

ABOUT THE JOURNAL

The Journal of Chemical Physics, published by the American Institute of Physics (AIP), contains concise and definitive reports of significant research in methods and applications of chemical physics. Innovative research in traditional areas of chemical physics such as spectroscopy, kinetics, statistical mechanics, and quantum mechanics continue to be areas of interest to readers of JCP. In addition, newer areas such as polymers, materials, surfaces/interfaces, information theory, and systems of biological relevance are of increasing importance. See: http://jcp.aip.org.

ABOUT AIP

The American Institute of Physics (AIP) is a not-for-profit membership corporation chartered in 1931 for the purpose of advancement and diffusion of the knowledge of physics and its application to human welfare. An umbrella organization for 10 Member Societies, AIP represents over 134,000 scientists, engineers and educators and is one of the world's largest publishers of physics journals. A total-solution provider of publishing services, AIP also publishes 12 journals of its own (many of which have the highest impact factors in their category), two magazines, and the AIP Conference Proceedings series. Its online publishing platform Scitation (registered trademark) hosts more than 1,000,000 articles from more than 175 scholarly journals, as well as conference proceedings, and other publications of 25 learned society publishers.

Devin Powell | EurekAlert!
Further information:
http://www.aip.org

More articles from Physics and Astronomy:

nachricht First evidence on the source of extragalactic particles
13.07.2018 | Technische Universität München

nachricht Simpler interferometer can fine tune even the quickest pulses of light
12.07.2018 | University of Rochester

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: First evidence on the source of extragalactic particles

For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.

To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...

Im Focus: Magnetic vortices: Two independent magnetic skyrmion phases discovered in a single material

For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.

Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...

Im Focus: Breaking the bond: To take part or not?

Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.

A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...

Im Focus: New 2D Spectroscopy Methods

Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.

"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....

Im Focus: Chemical reactions in the light of ultrashort X-ray pulses from free-electron lasers

Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.

Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Leading experts in Diabetes, Metabolism and Biomedical Engineering discuss Precision Medicine

13.07.2018 | Event News

Conference on Laser Polishing – LaP: Fine Tuning for Surfaces

12.07.2018 | Event News

11th European Wood-based Panel Symposium 2018: Meeting point for the wood-based materials industry

03.07.2018 | Event News

 
Latest News

Leading experts in Diabetes, Metabolism and Biomedical Engineering discuss Precision Medicine

13.07.2018 | Event News

Research finds new molecular structures in boron-based nanoclusters

13.07.2018 | Materials Sciences

Algae Have Land Genes

13.07.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>