. Nano Technology News .

Pull with caution
by Staff Writers
Trieste, Italy (SPX) Nov 15, 2012

This is an image of alpha-hemolysin pore (made up of 7 identical subunits in 7 colors) and 12-mer single-stranded DNA (in white) on the same scale to illustrate DNA effects on conductance when moving through a nanopore. Below is an orthogonal view of the same molecules. Image created 5-Oct-2008 by George Church using Rasmol_2.6 and coordinates from 7AHL.pdb and 1BNA.pdb. Credit: George Church.

As nanotechnology progresses, it becomes increasingly important to know in detail the dynamics of the nanoworld (the world at the scale of a millionth of a millimeter). What happens, for example, when we try to drive a polyelectrolyte (a long chain of electrically charged molecules, such as DNA) through a nanopore if knots cause the translocation process to jam?

It's not a pointless question, because now a new DNA sequencing method to electrochemically analyze every single strand by driving it through a nanopore, is being developed.

Since those strands tend to tangle up if they are very long, Angelo Rosa of the International School for Advanced Studies and his colleagues set out to study the dynamics of this translocation theoretically, by carrying out a simulation.

The model chosen by the scientists has shown that jamming is not caused by the mere presence of the knot, but by the relationship between friction and the force applied to drive the molecule into the gap.

"The result is not so obvious if compared to what happens at a macro level," explained Cristian Micheletti, researcher at SISSA and one of the authors of the paper published in Physical Review Letters.

"Knots introduce an effective friction that increases with the applied force and pulls the polymer to the other side of the nanopore. Translocation is only halted above a threshold force".

"According to what we observed in the simulation, to avoid obstruction of the pore and halt of the translocation, the force applied should be controlled, without pulling too much" explained Rosa.

This study is just a first step. For quantitative details on this process (what this threshold is and how the force should be measured out to maximize the effectiveness of this sequencing method) more in-depth examinations will be needed both at the theoretical (the model developed by Rosa, Di Ventra and Micheletti is mesoscopic, not atomistic) and at the experimental level.

Nanoporesequencing is an innovative technique, an alternative to more traditional methods such as PCA. This method involves separating the two nucleobase strands which make up the double helix of the DNA and analyzing them one by one.

Each strand is driven through a nanopore as the electric variations in the translocation are recorded.

That is an electrochemical method: alterations in the electric field give information on the chemical composition of the molecule driven through the pore and the composition is thus reconstructed.

Up to now this method has yielded good results with short DNA fragments, while difficulties have been encountered for longer ones, because of the knots. That's why studies such as Rosa, Di Ventra and Micheletti's are an important step to increase its efficiency.


Related Links
International School of Advanced Studies (SISSA)
Nano Technology News From SpaceMart.com
Computer Chip Architecture, Technology and Manufacture

Comment on this article via your Facebook, Yahoo, AOL, Hotmail login.

Share this article via these popular social media networks
del.icio.usdel.icio.us DiggDigg RedditReddit GoogleGoogle

Memory Foam Mattress Review

Newsletters :: SpaceDaily Express :: SpaceWar Express :: TerraDaily Express :: Energy Daily
XML Feeds :: Space News :: Earth News :: War News :: Solar Energy News

Get Our Free Newsletters
Space - Defense - Environment - Energy - Solar - Nuclear


What if the nanoworld slides
Trieste, Italy (SPX) Nov 15, 2012
A study published by Andrea Vanossi, Nicola Manini and Erio Tosatti - three SISSA researchers - in PNAS (Proceedings of the National Academy of Sciences) provides a new tool to better understand how sliding friction works in nanotribology, through colloidal crystals. By theoretically studying these systems of charged microparticles, researchers are able to analyze friction forces through m ... read more

China firm to invest $1.6 billion in plane engine

Airbus wins Chinese corporate jet order

Brazil airline opts for Rockwell Collins

China needs 4,960 planes by 2031: state media

China plans manned space launch in 2013: state media

China to launch manned spacecraft

Tiangong 1 Parked And Waiting As Shenzhou 10 Mission Prep Continues

China to launch 11 meteorological satellites by 2020

Chevron says hit by Stuxnet virus in 2010

WikiLeaks suspect offers guilty plea on some charges

White Paper: Cyber Security and Mobility Highest Priorities for Government

China's online censors prowl ahead of power handover

White Pavements Could Increase Energy Consumption in Surrounding Buildings

EU grid interconnection program targeted

Bulgaria and Europe depend on Russian energy exports

New Rule Could Reenergize Clean-Energy In New Jersey

Researchers have made the production of batteries cheaper and safer

More research on arctic oil spills urged

China to cut fuel prices for first time in four months

Prestige skipper blames Spain at oil disaster trial

Northrop Grumman Begins Full-Rate Production of LITENING SE Targeting Pods for USAF

Northrop Grumman and ITT Exelis Partner for U.S. Navy's Next Generation Jammer

Lockheed Martin Wins Contract to Enhance Combat Vehicle

Brazil's armored personnel carrier on way

Pull with caution

What if the nanoworld slides

Strain tuning reveals promise in nanoscale manufacturing

Low-resistance connections facilitate multi-walled carbon nanotubes for interconnects

Britain says no calculators for math tests

Off to the Future with a new Soccer Robot

Flying rescue robot can avoid obstacles

Advanced exoskeleton promises more independence for people with paraplegia

The content herein, unless otherwise known to be public domain, are Copyright 1995-2012 - Space Media Network. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA Portal Reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement,agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement