Navigation Links
Seeing is bead-lieving
Date:7/28/2014

HOUSTON (July 28, 2014) 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.


'/>"/>

Contact: Mike Williams
mikewilliams@rice.edu
713-348-6728
Rice University
Source:Eurekalert  

Related biology news :

1. University of Toronto researchers find seeing Jesus in Toast phenomenon perfectly normal
2. Seeing the bedrock through the trees
3. Computer models help decode cells that sense light without seeing
4. Monkeys can point to objects they do not report seeing
5. Seeing in the dark
6. Seeing the world through the eyes of an Orangutan
7. Seeing inside tissue
8. Stinging came before seeing
Post Your Comments:
*Name:
*Comment:
*Email:
Related Image:
Seeing is bead-lieving
(Date:2/28/2017)... -- News solutions for biometrics, bag drop and New ... At ... 16 March, Materna will present its complete end-to-end passenger journey, ... a real benefit for passengers. To accelerate the whole passenger ... point solutions to take passengers through the complete integrated process ...
(Date:2/26/2017)... DALLAS , Feb. 25, 2017  Securus ... justice technology solutions for public safety, investigation, corrections ... of Recidivism and Reentry. "Too often, ... State prisons and county jails are trying to ... of inmates and friends and family members. While significant ...
(Date:2/21/2017)... PORTLAND, Ore. , Feb. 22, 2017 /PRNewswire/ ... of Companies (Avamere Health Services, Infinity Rehab, Signature Hospice, ... study that will apply the power of IBM cognitive ... and health centers. By analyzing data streaming from sensors ... into physical and environmental conditions, and obtain deeper learnings ...
Breaking Biology News(10 mins):
(Date:3/29/2017)... , March 29, 2017 WuXi Biologics, ... company dedicated to biologics and a WuXi AppTec ... 2017 Asia-Pacific Best Bioprocessing Excellence Award from IMAPAC, ... Excellence Awards aims to recognize outstanding leaders and ... Featuring top bioprocessing and biomanufacturing experts in the ...
(Date:3/29/2017)... ... March 29, 2017 , ... (March 29, 2017) — ... been approved as an active member of the Mexican Direct Selling Association ... and consumers in relationship marketing. This professional organization fosters loyal and fair competition ...
(Date:3/29/2017)... March 29, 2017  Applied BioMath ( ... modeling to drug research and development, today ... Zymeworks Inc. for quantitative systems pharmacology (QSP) ... for the treatment of cancer. ... for GLP toxicology studies and first-in-human dose ...
(Date:3/29/2017)... MA (PRWEB) , ... March 29, 2017 , ... On ... centered on patient-involved research, Colpitts Clinical Trial Travel has announced that it will manage ... Direct Travel, was among the first in the United States and Europe to offer ...
Breaking Biology Technology: