Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Graphene crinkles can be used as 'molecular zippers'

01.02.2019

A decade ago, scientists noticed something very strange happening when buckyballs -- soccer ball shaped carbon molecules -- were dumped onto a certain type of multilayer graphene, a flat carbon nanomaterial. Rather than rolling around randomly like marbles on a hardwood floor, the buckyballs spontaneously assembled into single-file chains that stretched across the graphene surface.

Now, researchers from Brown University's School of Engineering have explained how the phenomenon works, and that explanation could pave the way for a new type of controlled molecular self-assembly.


This is a microscope view of tiny buckyballs lined up on a layered graphene surface. New research shows that that electrically charged crinkles in the graphene surface are responsible for the strange phenomenon.

Credit: Kim Lab / Brown University

In a paper published in Proceedings of the Royal Society A, the Brown team shows that tiny, electrically charged crinkles in graphene sheets can interact with molecules on the surface, arranging those molecules in electric fields along the paths of the crinkles.

"What we show is that crinkles can be used to create 'molecular zippers' that can hold molecules onto a graphene surface in linear arrays," said Kyung-Suk Kim, director of the Center for Advanced Materials Research in Brown's Institute for Molecular and Nanoscale Innovation and the study's senior author.

"This linear arrangement is something that people in physics and chemistry really want because it makes molecules much easier to manipulate and study."

The new paper is a follow-up to earlier research by Kim's team. In that first paper, they described how gently squeezing sheets of layered graphene from the side causes it to deform in a peculiar way. Rather than forming gently sloping wrinkles like you might find in a rug that's been scrunched against a wall, the compressed graphene forms pointy saw-tooth crinkles across the surface.

They form, Kim's research showed, because the arrangement of electrons in the graphene lattice causes the curvature of a wrinkle to localize along a sharp line. The crinkles are also electrically polarized, with crinkle peaks carrying a strong negative charge and valleys carrying a positive charge.

Kim and his team thought the electrical charges along the crinkles might explain the strange behavior of the buckyballs, partly because the type of multilayer graphene used in the original buckyball experiments was HOPG, a type of graphene that naturally forms crinkles when it's produced.

But the team needed to show definitely that the charge created by the crinkles could interact with external molecules on the graphene's surface. That's what the researchers were able to do in this new paper.

Their analysis using density functional theory, a quantum mechanical model of how electrons are arranged in a material, predicted that positively charged crinkle valleys should create an electrical polarization in the otherwise electrically neutral buckyballs.

That polarization should cause buckyballs to line up, each in the same orientation relative to each other and spaced around two nanometers apart.

Those theoretical predictions match closely the results of the original buckyball experiments as well as repeat experiments newly reported by Kim and his team.

The close agreement between theory and experiment helps confirm that graphene crinkles can indeed be used to direct molecular self-assembly, not only with buckyballs but potentially with other molecules as well.

Kim says that this molecular zippering capability could have many potential applications, particularly in studying biomolecules like DNA and RNA. For example, if DNA molecules can be stretched out linearly, it could be sequenced more quickly and easily. Kim and his team are currently working to see if this is possible.

"There's a lot of potential here to take advantage of crinkling and the interesting electrical properties they produce," Kim said.

###

Kim's co-authors on the paper were Mrityunjay Kothari, Moon-Hyun Cha and Victor Lefevre. The work was supported by the National Science Foundation (CMMI-1462785 and 1563591).

Media Contact

Kevin Stacey
kevin_stacey@brown.edu
401-863-3766

 @brownuniversity

http://news.brown.edu/ 

Kevin Stacey | EurekAlert!
Further information:
https://news.brown.edu/articles/2019/01/crinkles
http://dx.doi.org/10.1098/rspa.2018.0671

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Happy hour for time-resolved crystallography

Researchers from the Department of Atomically Resolved Dynamics of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg, the University of Hamburg and the European Molecular Biology Laboratory (EMBL) outstation in the city have developed a new method to watch biomolecules at work. This method dramatically simplifies starting enzymatic reactions by mixing a cocktail of small amounts of liquids with protein crystals. Determination of the protein structures at different times after mixing can be assembled into a time-lapse sequence that shows the molecular foundations of biology.

The functions of biomolecules are determined by their motions and structural changes. Yet it is a formidable challenge to understand these dynamic motions.

Im Focus: Modular OLED light strips

At the International Symposium on Automotive Lighting 2019 (ISAL) in Darmstadt from September 23 to 25, 2019, the Fraunhofer Institute for Organic Electronics, Electron Beam and Plasma Technology FEP, a provider of research and development services in the field of organic electronics, will present OLED light strips of any length with additional functionalities for the first time at booth no. 37.

Almost everyone is familiar with light strips for interior design. LED strips are available by the metre in DIY stores around the corner and are just as often...

Im Focus: Tomorrow´s coolants of choice

Scientists assess the potential of magnetic-cooling materials

Later during this century, around 2060, a paradigm shift in global energy consumption is expected: we will spend more energy for cooling than for heating....

Im Focus: The working of a molecular string phone

Researchers from the Department of Atomically Resolved Dynamics of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg, the University of Potsdam (both in Germany) and the University of Toronto (Canada) have pieced together a detailed time-lapse movie revealing all the major steps during the catalytic cycle of an enzyme. Surprisingly, the communication between the protein units is accomplished via a water-network akin to a string telephone. This communication is aligned with a ‘breathing’ motion, that is the expansion and contraction of the protein.

This time-lapse sequence of structures reveals dynamic motions as a fundamental element in the molecular foundations of biology.

Im Focus: Milestones on the Way to the Nuclear Clock

Two research teams have succeeded simultaneously in measuring the long-sought Thorium nuclear transition, which enables extremely precise nuclear clocks. TU Wien (Vienna) is part of both teams.

If you want to build the most accurate clock in the world, you need something that "ticks" very fast and extremely precise. In an atomic clock, electrons are...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Society 5.0: putting humans at the heart of digitalisation

10.09.2019 | Event News

Interspeech 2019 conference: Alexa and Siri in Graz

04.09.2019 | Event News

AI for Laser Technology Conference: optimizing the use of lasers with artificial intelligence

29.08.2019 | Event News

 
Latest News

Novel mechanism of electron scattering in graphene-like 2D materials

17.09.2019 | Materials Sciences

Novel anti-cancer nanomedicine for efficient chemotherapy

17.09.2019 | Health and Medicine

Fungicides as an underestimated hazard for freshwater organisms

17.09.2019 | Ecology, The Environment and Conservation

VideoLinks
Science & Research
Overview of more VideoLinks >>>