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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Body’s molecular sensors may trigger autoimmune disease

ScienceDaily (Oct. 27, 2011) — Bruce Beutler, MD, a co-recipient of the 2011 Nobel Prize in Medicine, has coauthored an article describing a novel molecular mechanism that can cause the body to attack itself and trigger an autoimmune disease. The article is published online ahead of print in the Journal of Interferon & Cytokine Research, a peer-reviewed journal published by Mary Ann Liebert, Inc.

In the article, entitled "Intracellular Nucleic Acid Sensors and Autoimmunity," Argyrios Theofilopoulos, Dwight Kono, Bruce Beutler, and Roberto Baccala, The Scripps Research Institute (La Jolla, California), review the scientific evidence that supports the role of molecular sensors located inside cells in the initiation not only of protective and inflammatory immune responses, but also in an autoimmune response. These sensors recognize nucleic acid signatures that may be shared by foreign pathogens and the body's own DNA and RNA.

Dr. Beutler is one of three recipients awarded the Nobel Prize in Physiology and Medicine. He shares half of the prize with Jules Hoffman, PhD for their discoveries related to how the body's immune system fights disease through the activation of an innate immune response. The third recipient, Ralph Steinman, MD, who died before the Nobel Prizes were announced, previously published an article in AIDS Research and Human Retroviruses. Mary Ann Liebert, Inc. congratulates the three winners for the work and contributions to medicine for which they are being recognized.

The Journal of Interferon & Cytokine Research, led by Co-Editors-in-Chief Ganes C. Sen, PhD, Chairman, Department of Molecular Genetics, Cleveland Clinic Foundation, and Thomas A. Hamilton, PhD, Chairman, Department of Immunology, Cleveland Clinic Foundation, is an authoritative peer-reviewed journal published monthly in print and online that covers all aspects of interferons and cytokines from basic science to clinical applications. Journal of Interferon & Cytokine Research is the Official Journal of the International Society for Interferon and Cytokine Research. Tables of content and a free sample issue may be viewed online at www.liebertpub.com/jir

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Journal References:

Argyrios N. Theofilopoulos, Dwight H. Kono, Bruce Beutler, Roberto Baccala. Intracellular Nucleic Acid Sensors and Autoimmunity. Journal of Interferon & Cytokine Research, 2011; 111027061355005 DOI: 10.1089/jir.2011.0092Ralf Ignatius, Yang Wei, Sylvie Beaulieu, Agegnehu Gettie, Ralph M. Steinman, Melissa Pope, Svetlana Mojsov. Short Communication: The Immunodeficiency Virus Coreceptor, Bonzo/STRL33/TYMSTR, Is Expressed by Macaque and Human Skin- and Blood-Derived Dendritic Cells. AIDS Research and Human Retroviruses, 2000; 16 (11): 1055 DOI: 10.1089/08892220050075318

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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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