Nanoscopic static electricity generates chiral patterns

February 01, 2009

In the tiny world of amino acids and proteins and in the helical shape of DNA, a biological phenomenon abounds.

These objects are all chiral -- they cannot exactly superimpose their mirror image by translation or rotation. A common example of this is human hands -- a right hand cannot superimpose itself into its mirror image, a left hand. This description of a molecule's symmetry (or lack thereof) is important in determining the molecule's properties in chemistry.

But while scientists and engineers know that at the sub-atomic level weak forces are chiral, how these electrostatic forces can generate a chiral world is still a mystery.

Researchers at Northwestern University in the group of Monica Olvera de la Cruz, professor of materials science and engineering and chemical and biological engineering at the McCormick School of Engineering and Applied Science, have recently shown how electrostatic interactions -- commonly known as static electricity -- alone can give rise to helical shapes. The group has constructed a mathematical model that can capture all possible regular shapes chiral objects could have, and they computed the preferred arrangements induced by electrostatic interactions.

Their work will be published as the cover story in the journal Soft Matter and is published online.

"In this way we are simply letting nature tell us how it would like to be, and we generalize it to many different systems," Olvera de la Cruz says." She and her colleagues report that chirality can only spontaneously arise as a consequence of electrostatic interactions and does not require the presence of other more complicated interactions, like dipolar or short-range van der Waals interactions.

Their model also describes arrangement of DNA mixed with carbon nanotubes. DNA has been shown to form helices around nanotubes, thereby separating the different types of carbon nanotubes into families.

The research findings concur with previous research using microscopy.

"From our predicted helical shapes of DNA wrapped around carbon nanotubes, we found amazing correspondence to those that were recently measured by atomic force microscopy," Olvera de le Cruz says.

The work shows that electrostatics is a pathway for understanding how nature generates helical symmetries. Researchers hope that future work can show how to use simple interactions to generate other symmetries that drive complex phenomena.
-end-
The research was done in the department of materials science and engineering. Graziano Vernizzi, research assistant professor, and Kevin Kohlstedt, graduate student, co-authored the paper.

The work was supported by the Department of Energy Computational Science Graduate Fellowship and the National Science Foundation.

Northwestern University

Related DNA Articles from Brightsurf:

A new twist on DNA origami
A team* of scientists from ASU and Shanghai Jiao Tong University (SJTU) led by Hao Yan, ASU's Milton Glick Professor in the School of Molecular Sciences, and director of the ASU Biodesign Institute's Center for Molecular Design and Biomimetics, has just announced the creation of a new type of meta-DNA structures that will open up the fields of optoelectronics (including information storage and encryption) as well as synthetic biology.

Solving a DNA mystery
''A watched pot never boils,'' as the saying goes, but that was not the case for UC Santa Barbara researchers watching a ''pot'' of liquids formed from DNA.

Junk DNA might be really, really useful for biocomputing
When you don't understand how things work, it's not unusual to think of them as just plain old junk.

Designing DNA from scratch: Engineering the functions of micrometer-sized DNA droplets
Scientists at Tokyo Institute of Technology (Tokyo Tech) have constructed ''DNA droplets'' comprising designed DNA nanostructures.

Does DNA in the water tell us how many fish are there?
Researchers have developed a new non-invasive method to count individual fish by measuring the concentration of environmental DNA in the water, which could be applied for quantitative monitoring of aquatic ecosystems.

Zigzag DNA
How the cell organizes DNA into tightly packed chromosomes. Nature publication by Delft University of Technology and EMBL Heidelberg.

Scientists now know what DNA's chaperone looks like
Researchers have discovered the structure of the FACT protein -- a mysterious protein central to the functioning of DNA.

DNA is like everything else: it's not what you have, but how you use it
A new paradigm for reading out genetic information in DNA is described by Dr.

A new spin on DNA
For decades, researchers have chased ways to study biological machines.

From face to DNA: New method aims to improve match between DNA sample and face database
Predicting what someone's face looks like based on a DNA sample remains a hard nut to crack for science.

Read More: DNA News and DNA Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.