Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Self-assembling nano-ice discovered at UNL; structure resembles DNA

14.12.2006
Working at the frontier between chemistry and physics, the University of Nebraska-Lincoln's Xiao Cheng Zeng usually finds his reward in discovering the unexpected through computer modeling.

Zeng and his colleagues regularly find new and often unanticipated behaviors of matter in extreme environments, and those discoveries have been published several times in major international scientific journals. Their findings, though, have been so far ahead of existing technology that their immediate practical impact was essentially nil -- until now.

Zeng and two members of his UNL team recently found double helixes of ice molecules that resemble the structure of DNA and self-assemble under high pressure inside carbon nanotubes. This discovery could have major implications for scientists in other fields who study the protein structures that cause diseases such as Alzheimer's and bovine spongiform ecephalitis (mad cow disease). It could also help guide those searching for ways to target or direct self-assembly in nanomaterials and predict the kind of ice future astronauts will find on Mars and moons in the solar system.

Zeng, post-doctoral student Jaeil Bai and doctoral candidate Jun Wang reported their findings in the Dec. 11-15 online edition of the Proceedings of the National Academy of Sciences.

... more about:
»Bai »Carbon »DNA »Helix »Simulation »Zeng »nano-ice »self-assembly

Zeng and his colleagues use powerful computers to model how materials behave at the nanoscale (where measurements are made in billionths of meters) under extremes of temperature, pressure and confinement. The team found the self-assembling double helix of nano-ice following a months-long experiment on UNL's PrairieFire supercomputer.

The experiment was a follow-up on a 2001 discovery through computer modeling by Zeng and another team of four new kinds of one-dimensional ice inside carbon nanotubes. Scientists elsewhere later confirmed through laboratory experiment the existence of three of the new nano-ices. One result in particular intrigued Zeng, Bai and Wang. Scientists at Argonne National Laboratory near Chicago confirmed the existence of a chain of octagon-shaped ice crystals inside a 1.4-nanometer carbon tube, just as Zeng and company expected. But the Argonne group also found an additional, unexpected chain of water molecules inside the octagon.

Zeng said that report inspired his team to take another look at one-dimensional ice, but this time with a PrairieFire that was 20 times more powerful that it had been five years earlier. The 2001 results were achieved at atmospheric pressures, but PrairieFire's added processing power enabled Zeng, Bai and Wang to design simulations that greatly increased the pressure on the water molecules.

"We were shocked to see these molecules arrange themselves in this way," said Zeng, university professor of chemistry. "We thought it would be like two tubes, one inside the other, but it didn't do that. It was helical, like DNA. I'm just speculating, but maybe the helix is a way for molecules to arrange themselves in a very compact, efficient way under high pressure.

"This ice formation can be viewed as a self-assembling process, and self-assembly is a way for molecules to bond together through weak hydrogen bonds. One example of a self-assembling material is protein. Proteins can self-assemble into structures like amyloid fibrils that can build up in the brain to cause Alzheimer's disease or prions that cause mad cow disease."

Another implication, Zeng said, is that these self-assembling helical ice structures may give scientists and engineers a different way to think about weak molecular bonds and the self-assembly process as they try to develop ways to direct self-assembly in making new materials. He said that while scientists have a good understanding of covalent bonds (the strong type of bonding where atoms share electrons), knowledge is not as complete about the weak bond, such as hydrogen bonds, that are essential to the self-assembly process. In weak bonding, atoms don't share electrons.

"We're happy to see potential applications that can maybe advance some fundamental science," Zeng said. "We're not engineers in direct contact with technology, but if our research can make some contribution, we're happy."

Zeng and his colleagues achieved their results by running four series of molecular dynamics simulations on PrairieFire and Department of Chemistry computers, using simulated carbon nanotubes ranging in diameter from 1.35 to 1.9 nanometers. They used Earth-like temperatures ranging from 117 degrees Fahrenheit to 9 degrees below zero F., but with pressures ranging from 10 to 40,000 atmospheres, with each series lasting no more than a few 10s of nanoseconds.

Most of the experiments produced the expected tubular structures, but in a simulation in a 1.35-nanometer tube at minus-9 degrees F. and 40,000 atmospheres, the ice transformed into a braid of double helix that resembles DNA in structure and in the weak bonds between the helixes. Additionally, in a simulation in a 1.9-nanometer tube at the same temperature, pressure on the confined liquid water was instantly raised from 10 atmospheres to 8,000. The confined liquid froze spontaneously into a high-density, triple-walled helical structure.

This research was funded by the Department of Energy, the National Science Foundation, the Nebraska Research Initiative and the John Simon Guggenheim Foundation.

The links below are to color JPEGs of a computer image of of the nano-ice double helix and of Zeng and his team. In the nano-ice image, oxygen atoms are blue in the inner helix, purple in the outer helix. Hydrogen atoms are white. The individuals in the photograph, left-to-right, are Wang, Zeng and Bai.

CONTACTS: Xiao Cheng Zeng, University Professor, Chemistry, (402) 472-9894
Tom Simons, University Communications, (402) 472-8514

Kelly Bartling | EurekAlert!
Further information:
http://www.unl.edu

Further reports about: Bai Carbon DNA Helix Simulation Zeng nano-ice self-assembly

More articles from Life Sciences:

nachricht Historical rainfall levels are significant in carbon emissions from soil
30.05.2017 | University of Texas at Austin

nachricht 3D printer inks from the woods
30.05.2017 | Empa - Eidgenössische Materialprüfungs- und Forschungsanstalt

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: New Method of Characterizing Graphene

Scientists have developed a new method of characterizing graphene’s properties without applying disruptive electrical contacts, allowing them to investigate both the resistance and quantum capacitance of graphene and other two-dimensional materials. Researchers from the Swiss Nanoscience Institute and the University of Basel’s Department of Physics reported their findings in the journal Physical Review Applied.

Graphene consists of a single layer of carbon atoms. It is transparent, harder than diamond and stronger than steel, yet flexible, and a significantly better...

Im Focus: Strathclyde-led research develops world's highest gain high-power laser amplifier

The world's highest gain high power laser amplifier - by many orders of magnitude - has been developed in research led at the University of Strathclyde.

The researchers demonstrated the feasibility of using plasma to amplify short laser pulses of picojoule-level energy up to 100 millijoules, which is a 'gain'...

Im Focus: Can the immune system be boosted against Staphylococcus aureus by delivery of messenger RNA?

Staphylococcus aureus is a feared pathogen (MRSA, multi-resistant S. aureus) due to frequent resistances against many antibiotics, especially in hospital infections. Researchers at the Paul-Ehrlich-Institut have identified immunological processes that prevent a successful immune response directed against the pathogenic agent. The delivery of bacterial proteins with RNA adjuvant or messenger RNA (mRNA) into immune cells allows the re-direction of the immune response towards an active defense against S. aureus. This could be of significant importance for the development of an effective vaccine. PLOS Pathogens has published these research results online on 25 May 2017.

Staphylococcus aureus (S. aureus) is a bacterium that colonizes by far more than half of the skin and the mucosa of adults, usually without causing infections....

Im Focus: A quantum walk of photons

Physicists from the University of Würzburg are capable of generating identical looking single light particles at the push of a button. Two new studies now demonstrate the potential this method holds.

The quantum computer has fuelled the imagination of scientists for decades: It is based on fundamentally different phenomena than a conventional computer....

Im Focus: Turmoil in sluggish electrons’ existence

An international team of physicists has monitored the scattering behaviour of electrons in a non-conducting material in real-time. Their insights could be beneficial for radiotherapy.

We can refer to electrons in non-conducting materials as ‘sluggish’. Typically, they remain fixed in a location, deep inside an atomic composite. It is hence...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Marine Conservation: IASS Contributes to UN Ocean Conference in New York on 5-9 June

24.05.2017 | Event News

AWK Aachen Machine Tool Colloquium 2017: Internet of Production for Agile Enterprises

23.05.2017 | Event News

Dortmund MST Conference presents Individualized Healthcare Solutions with micro and nanotechnology

22.05.2017 | Event News

 
Latest News

3D printer inks from the woods

30.05.2017 | Life Sciences

How circadian clocks communicate with each other

30.05.2017 | Life Sciences

Graphene and quantum dots put in motion a CMOS-integrated camera that can see the invisible

30.05.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>