Nanotechnology Now

Our NanoNews Digest Sponsors





Heifer International

Wikipedia Affiliate Button


android tablet pc

Home > Press > Polymer passage takes time

Abstract:
New theory aids researchers studying DNA, protein transport

Polymer passage takes time

Houston, TX | Posted on July 29th, 2010

Polymer strands wriggle their way through nanometer-sized pores in a membrane to get from here to there and do their jobs. New theoretical research by Rice University scientists quantifies precisely how long the journey takes.

That's a good thing to know for scientists studying the transport of RNA, DNA and proteins -- all of which count as polymers -- or those who are developing membranes for use in biosensors or as drug-delivery devices.

Researchers led by Anatoly Kolomeisky, an associate professor of chemistry and of chemical and biomolecular engineering, have come up with a theoretical method to calculate the time it takes for long-chain polymers to translocate through nano-sized channels in membranes, like the one that separates the nucleus of a cell from surrounding cytoplasm. RNA molecules have to make this intracellular trip, as do proteins that pass through a cell's exterior membrane to perform tasks in the body.

Primary author Kolomeisky reported the findings this month in the Journal of Chemical Physics. Study co-authors include Aruna Mohan, a former postdoctoral research associate at Rice and now a researcher at Exxon-Mobil, and Matteo Pasquali, professor in chemical and biomolecular engineering and chemistry.

The team studied the translocation of a long polymer molecule, which roughly resembles beads on a string, through two types of nanopore geometries: a cylinder and a two-cylinder composite that resembled a large tube connected to a small tube. Not surprisingly, they found a polymer passed more quickly when entering the composite through the wide end.

"We assume the polymer is relatively large in comparison with the size of the pore, which is realistic," Kolomeisky said of the process, which is akin to threading a rope through a peephole. "A typical strand of DNA could be a thousand nanometers long, and the pore could have a length of a few nanometers."

It's been known for some time that polymers don't just fly through a pore, even when they find the opening. They start. They stop. They start again. And once the leading end has entered a pore, it can back out. Polymers often jitter backward and forward as they progress through a pore, constantly reconfiguring themselves.

"Previous theorists thought that as soon as the leading end reached the channel, the whole polymer would go through," he said. "We're saying it goes back and forth many times before it finally passes."

The key to an accurate description of polymer translocation with single-molecule precision is measuring electric currents that go through the pore. "When the current is high, there's no polymer in the channel. When the current is down, it's in the pore and blocking the flux," he said.

Experiments indicate typical DNA and RNA molecules could pass through a membrane in a few milliseconds, depending on the strength of the electric field driving them. But even that, he said, is much longer than researchers previously thought.

Kolomeisky said the new method works for pores of any geometry, whether they're straight, conical or made of joined cylinders of different sizes, like the hemolysin biological channel they simulated in their research.

The calculations apply equally to natural or artificial pores, which he said would be important to scientists making membranes for drug delivery, biosensors or water purification processes, or researching new methods for sequencing DNA.

Grants from the Welch Foundation and the National Science Foundation supported the research.

Read the abstract at jcp.aip.org/jcpsa6/v133/i2/p024902_s1

####

For more information, please click here

Contacts:
Mike Williams
PHONE: 713-348-6728

Copyright © Rice University

If you have a comment, please Contact us.

Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Bookmark:
Delicious Digg Newsvine Google Yahoo Reddit Magnoliacom Furl Facebook

Related News Press

News and information

Imec Reports Four Percent Growth for 2013 Fiscal Year End —Continues to Accelerate Innovation Through Global Collaborations and Technological Breakthroughs in Nanoelectronics— April 24th, 2014

Multicapacity Microreactor for Catalyst Characterisation April 24th, 2014

Making graphene work for real-world devices: Fundamental research in phonon scattering helps researchers design graphene materials for applications April 24th, 2014

Return on investment for kit and promotion materials April 24th, 2014

Academic/Education

Global leader in solar cell manufacturing eyes New York for major expansion outside of Japan: CNSE and Solar Frontier Explore $700 Million Investment, Job Creation in New York State April 22nd, 2014

University of Waterloo Visits China to Strengthen Bonds With Research Partners April 21st, 2014

Director Wally Pfister joins UC Berkeley neuroengineers to discuss the science behind ‘Transcendence’ April 7th, 2014

First annual science week highlights STEM pipeline and partnerships: UB, SUNY Buffalo State and ECC team up with the City of Buffalo and its schools for April 7-11 events April 3rd, 2014

Nanomedicine

Return on investment for kit and promotion materials April 24th, 2014

University of Tehran Researchers Invent Non-Enzyme Sensor to Detect Blood Sugar April 23rd, 2014

Gold nanoparticles help target, quantify breast cancer gene segments in a living cell April 23rd, 2014

QuantuMDx announce prototype handheld lab for 15 minute malaria diagnosis and drug resistance testing April 23rd, 2014

Sensors

University of Tehran Researchers Invent Non-Enzyme Sensor to Detect Blood Sugar April 23rd, 2014

Iranian Researchers Present New Model to Strengthen Superconductivity at Higher Temperatures April 19th, 2014

Transparent Conductive Films and Sensors Are Hot Segments in Printed Electronics: Start-ups in these fields show above-average momentum, while companies working on emissive displays such as OLED are fading, Lux Research says April 17th, 2014

Biologists Develop Nanosensors to Visualize Movements and Distribution of Plant Stress Hormone April 15th, 2014

Announcements

Imec Reports Four Percent Growth for 2013 Fiscal Year End —Continues to Accelerate Innovation Through Global Collaborations and Technological Breakthroughs in Nanoelectronics— April 24th, 2014

Multicapacity Microreactor for Catalyst Characterisation April 24th, 2014

Making graphene work for real-world devices: Fundamental research in phonon scattering helps researchers design graphene materials for applications April 24th, 2014

Return on investment for kit and promotion materials April 24th, 2014

Grants/Awards/Scholarships/Gifts/Contests/Honors/Records

Imec Reports Four Percent Growth for 2013 Fiscal Year End —Continues to Accelerate Innovation Through Global Collaborations and Technological Breakthroughs in Nanoelectronics— April 24th, 2014

National Space Society Congratulates SpaceX on the Success of CRS-3 and the First Flight of the Falcon 9R April 22nd, 2014

Energy Research Facility Construction Project at Brookhaven Lab Wins U.S. Energy Secretary's Achievement Award April 16th, 2014

IDTechEx Printed Electronics Europe 2014 Award Winners April 1st, 2014

Nanobiotechnology

University of Tehran Researchers Invent Non-Enzyme Sensor to Detect Blood Sugar April 23rd, 2014

Gold nanoparticles help target, quantify breast cancer gene segments in a living cell April 23rd, 2014

Guo Lab Shows Potential of RNA as Heat-resistant Polymer Material for Nanoarchitectures April 23rd, 2014

Cloaked DNA nanodevices survive pilot mission: Successful foray opens door to virus-like DNA nanodevices that could diagnose diseased tissues and manufacture drugs to treat them April 22nd, 2014

NanoNews-Digest
The latest news from around the world, FREE







  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoTech-Transfer
University Technology Transfer & Patents
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More














ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project







© Copyright 1999-2014 7th Wave, Inc. All Rights Reserved PRIVACY POLICY :: CONTACT US :: STATS :: SITE MAP :: ADVERTISE