麻豆淫院

(麻豆淫院Org.com) -- 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鈥檛 the latest gadget from James Bond鈥檚 arsenal -- rather, the latest research from the DOE鈥檚 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.

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

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 鈥� a bath of water with Teflon-coated paddles at either end 鈥� 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, 鈥渨e can squeeze this layer to a critical pressure and watch it collapse into a sheet.鈥�

鈥淜nowing the mechanism of sheet formation gives us a set of design rules for making these nanomaterials on a much larger scale,鈥� 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.

鈥淒uring 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,鈥� added Zuckermann.  鈥淲hat鈥檚 more, this process may be general for a wide variety of two-dimensional nanomaterials.鈥�

This research is reported in a paper titled, 鈥淪haken, not stirred: Collapsing a peptoid monolayer to produce free-floating, stable nanosheets,鈥� 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.