Featured Research

from universities, journals, and other organizations

Models for polymer macromolecules using magnets and DNA 'springs'

Date:
July 28, 2014
Source:
Rice University
Summary:
Scientists are making models for polymer macromolecules using magnets and DNA 'springs' that can be tuned for flexibility.

DNA linkers serve as bridges between colloidal beads in a new experiment by Rice University scientists to study the physics of “bead-spring” polymer chains. They found the chains can be tuned for varying degrees of stiffness or flexibility.
Credit: Biswal Lab/Rice University

Rice University researchers are using magnetic beads and DNA "springs" to create chains of varying flexibility that can be used as microscale models for polymer macromolecules. The experiment is visual proof that "bead-spring" polymers, introduced as theory in the 1950s, can be made as stiff or as flexible as required and should be of interest to materials scientists who study the basic physics of polymers.

The work led by Rice chemical and biomolecular engineer Sibani Lisa Biswal and graduate student Julie Byrom was published this month in the American Chemical Society journal Langmuir.

The researchers found the best way to study the theory was to assemble chains of micron-sized colloidal beads with nanoscale DNA springs of various lengths.

"Polymers are classically described as beads connected with springs," Biswal said. "A lot of polymer physicists have come up with scaling laws and intuitive polymer properties based on this very simple concept. But there are very few bead-spring model systems that you can actually visualize. That's why this work came about."

Microscopic solids suspended in a liquid like the fat particles in milk or pigment particles in paint are examples of a colloidal system. Biswal said there has been great interest in creating colloidal molecules, and the Rice experiment is a step in that direction.

To make complex colloidal macromolecules, the researchers started with commercially available, iron-rich polystyrene beads coated with a protein, streptavidin. The beads are charged to repel each other but can connect together with springy DNA fragments. The chains formed when the researchers exposed the beads to a magnetic field.

"We use the field to control particle positioning, let the DNA link the beads together and turn the field off," Biswal said, explaining how the chains self-assemble. "This is a nice system for polymers, because it's large enough to visualize individual beads and positioning, but it's small enough that thermal (Brownian) forces still dictate the chain's motion."

As expected, when they made chains with short (about 500 base pairs) DNA bridges, the macromolecule remained stiff. Longer linkers (up to 8,000 base pairs) appeared to coil up between the beads, allowing for movement in the chain. Surprisingly, when the researchers reapplied the magnetic field to stretch the long links, they once again became rigid.

"Our vision of what's happening is that DNA allows some wiggle room between particles and gives the chain elasticity," Biswal said. "But if the particles are pulled far enough apart, you stress the bridge quite a bit and reduce the freedom it has to move."

Being able to engineer such a wide range of flexibilities allows for more complex materials that can be actuated with magnetic fields, Biswal said.

"This research is interesting because until now, people haven't been able to make flexible chains like this," Byrom said. "We want to be able to explain what's happening across a broad range of polymers, but if you can only make rigid chains, it sort of limits what you can talk about."

Now that they can create polymer chains with predictable behavior, the researchers plan to study how the chains react to shifting magnetic fields over time, as well as how the chains behave in fluid flows.

The paper's co-authors are Rice alum Patric Han and undergraduate Michael Savory. The National Science Foundation supported the research.


Story Source:

The above story is based on materials provided by Rice University. The original article was written by Mike Williams. Note: Materials may be edited for content and length.


Journal Reference:

  1. Julie Byrom, Patric Han, Michael Savory, Sibani Lisa Biswal. Directing Assembly of DNA-Coated Colloids with Magnetic Fields To Generate Rigid, Semiflexible, and Flexible Chains. Langmuir, 2014; 140723081929004 DOI: 10.1021/la5009939

Cite This Page:

Rice University. "Models for polymer macromolecules using magnets and DNA 'springs'." ScienceDaily. ScienceDaily, 28 July 2014. <www.sciencedaily.com/releases/2014/07/140728113355.htm>.
Rice University. (2014, July 28). Models for polymer macromolecules using magnets and DNA 'springs'. ScienceDaily. Retrieved September 21, 2014 from www.sciencedaily.com/releases/2014/07/140728113355.htm
Rice University. "Models for polymer macromolecules using magnets and DNA 'springs'." ScienceDaily. www.sciencedaily.com/releases/2014/07/140728113355.htm (accessed September 21, 2014).

Share This



More Matter & Energy News

Sunday, September 21, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

What This MIT Sensor Could Mean For The Future Of Robotics

What This MIT Sensor Could Mean For The Future Of Robotics

Newsy (Sep. 20, 2014) MIT researchers developed a light-based sensor that gives robots 100 times the sensitivity of a human finger, allowing for "unprecedented dexterity." Video provided by Newsy
Powered by NewsLook.com
MIT BioSuit A New Take On Traditional Spacesuits

MIT BioSuit A New Take On Traditional Spacesuits

Newsy (Sep. 19, 2014) The MIT BioSuit could be an alternative to big, bulky traditional spacesuits, but the concept needs some work. Video provided by Newsy
Powered by NewsLook.com
New Music With Recycled Instruments at Colombia Fest

New Music With Recycled Instruments at Colombia Fest

AFP (Sep. 19, 2014) Jars, bottles, caps and even a pizza box, recovered from the trash, were the elements used by four musical groups at the "RSFEST2014 Sonorities Recycling Festival", in Colombian city of Cali. Duration: 00:49 Video provided by AFP
Powered by NewsLook.com
Virtual Reality Headsets Unveiled at Tokyo Game Show

Virtual Reality Headsets Unveiled at Tokyo Game Show

AFP (Sep. 18, 2014) Several companies unveiled virtual reality headsets at the Tokyo Game Show, Asia's largest digital entertainment exhibition. Duration: 00:48 Video provided by AFP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins