Nanotechnology Now

Our NanoNews Digest Sponsors





Heifer International

Wikipedia Affiliate Button


DHgate

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

Non-Enzyme Sensor Determines Level of Blood Sugar July 29th, 2015

Flexible Future of Point-of-Care Disease Diagnostic July 29th, 2015

Meet the high-performance single-molecule diode: Major milestone in molecular electronics scored by Berkeley Lab and Columbia University team July 29th, 2015

Detecting small metallic contaminants in food via magnetization: A practical metallic-contaminant detecting system using three high-Tc RF superconducting quantum interference devices (SQUIDs) July 29th, 2015

Academic/Education

Deben reports on the use of their CT500 in the X-ray microtomography laboratory at La Trobe University, Melbourne, Australia July 22nd, 2015

JPK reports on the use of SPM in the Messersmith Group at UC Berkeley looking at biologically inspired polymer adhesives. July 21st, 2015

Renishaw adds Raman analysis to Scanning Electron Microscopy at the University of Sydney, Australia July 9th, 2015

Oxford Instrumentsí TritonXL Cryofree dilution refrigerator selected for the Oxford NQIT Quantum Technology Hub project June 30th, 2015

Nanomedicine

March 2016; 6th Int'l Conference on Nanostructures in Iran July 29th, 2015

Non-Enzyme Sensor Determines Level of Blood Sugar July 29th, 2015

Flexible Future of Point-of-Care Disease Diagnostic July 29th, 2015

Stretching the limits on conducting wires July 25th, 2015

Sensors

Non-Enzyme Sensor Determines Level of Blood Sugar July 29th, 2015

American Chemical Society expands reach to include rapidly emerging area of sensor science July 25th, 2015

UT Dallas nanotechnology research leads to super-elastic conducting fibers July 24th, 2015

Iranian Scientists Create Best Conditions for Synthesis of Gold Nanolayers July 23rd, 2015

Announcements

Non-Enzyme Sensor Determines Level of Blood Sugar July 29th, 2015

Flexible Future of Point-of-Care Disease Diagnostic July 29th, 2015

Meet the high-performance single-molecule diode: Major milestone in molecular electronics scored by Berkeley Lab and Columbia University team July 29th, 2015

Detecting small metallic contaminants in food via magnetization: A practical metallic-contaminant detecting system using three high-Tc RF superconducting quantum interference devices (SQUIDs) July 29th, 2015

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

UT Dallas nanotechnology research leads to super-elastic conducting fibers July 24th, 2015

Leti and Diabeloop Project Aims at Developing Artificial Pancreas for Diabetes Treatment July 22nd, 2015

Rice University finding could lead to cheap, efficient metal-based solar cells: Plasmonics study suggests how to maximize production of 'hot electrons' July 22nd, 2015

Smarter window materials can control light and energy July 22nd, 2015

Nanobiotechnology

New computer model could explain how simple molecules took first step toward life: Two Brookhaven researchers developed theoretical model to explain the origins of self-replicating molecules July 28th, 2015

Spintronics: Molecules stabilizing magnetism: Organic molecules fixing the magnetic orientation of a cobalt surface/ building block for a compact and low-cost storage technology/ publication in Nature Materials July 25th, 2015

Programming adult stem cells to treat muscular dystrophy and more by mimicking nature July 22nd, 2015

Biophotonics - Global Strategic Business Report 2015 July 21st, 2015

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