Video | Business Headlines | Internet | Science | Scientific Ethics | Technology | Search

 


Researchers Develop Models To Study Polyelectrolytes

Aug. 21, 2014

Researchers Develop Models To Study Polyelectrolytes, Including DNA and RNA

Researchers from North Carolina State University have developed a novel and versatile modeling strategy to simulate polyelectrolyte systems. The model has applications for creating new materials as well as for studying polyelectrolytes, including DNA and RNA.

“Our new technique allows us to model much larger and more complex polyelectrolyte systems, and to do so much more quickly,” says Nan Li, lead author of a paper on the work and a Ph.D. student in NC State’s Department of Materials Science and Engineering. “This is a big step forward for this field.”

Polyelectrolytes are chains of molecules that are positively or negatively charged when placed in water. Because they are sensitive to changes in their environment, polyelectrolytes hold promise for use in applications such as drug delivery mechanisms. The term polyelectrolyte system refers to any collection of molecules that interacts in some way and includes polyelectrolytes.

Researchers are interested in computation models that simulate the behavior of polyelectrolyte systems because these models can be used to determine which polyelectrolytes are most likely to have desirable characteristics for use in various applications. The models can also be used to help researchers understand the behavior of polyelectrolyte systems such as DNA, RNA or synthetic ionic polymers.

Polyelectrolyte systems are difficult to model, because the systems can be large and include a lot of ions that can interact with the polyelectrolytes, changing the actual charge, shape, properties and behaviors of the polyelectrolytes. The change in charge affects how the polyelectrolytes interact with each other. The more ions there are in the system, the more likely it is that the polyelectrolytes will be drawn to each other. This interaction of polyelectrolytes changes the behavior and characteristics of the overall system.

“The problem is that tracking all of the ion-polyelectrolyte interactions takes a lot of computing power,” Li says. “We’ve developed a more efficient technique to account for the effect of the ions, and that allows us to use less computing power and get quicker results. The computational cost of calculating the electrostatic interactions between the ions and polyelectrolytes is reduced to zero because the parameter is already accounted for within an existing model.”

“Previous modeling techniques took an explicit approach, accounting for each individual ion,” says William Fuss, an undergraduate at NC State and co-author of the paper. “Our technique takes an implicit approach, which is why we call it the ‘implicit solvent ionic strength method,’ or ISIS. We use a single parameter to control for the effect of the ions in a Dissipative Particle Dynamics model, which is already in widespread use. That means our method could be easily implemented by anyone using DPD software.”

Using the ISIS method, researchers can identify potential polyelectrolyte system candidates for an application and then control the behavior of the polyelectrolytes by tweaking the number of ions in the system. This is done by increasing the concentration of salts in the system, because all salts are ionic when in an aqueous solution.

A video using the ISIS model to illustrate the behavior of a polyelectrolyte system can be seen at http://www.youtube.com/watch?v=HdY7VqgWzzA. The video is of self-assembling polyelectrolyte diblock copolymers in an aqueous solution.

The paper, “An implicit solvent ionic strength (ISIS) method to model polyelectrolyte systems with dissipative particle dynamics,” is published online in the journal Macromolecular Theory and Simulations. Senior author of the paper is Dr. Yaroslava Yingling, an associate professor of materials science and engineering at NC State. The research was supported by the National Science Foundation under grants CMMI-1150682 and DMR-1121107.

-shipman-

he study abstract follows.

“An implicit solvent ionic strength (ISIS) method to model polyelectrolyte systems with dissipative particle dynamics”

Authors: Nan K. Li, William H. Fuss, and Yaroslava G. Yingling, North Carolina State University

Published: Aug. 14 in Macromolecular Theory and Simulations

Abstract: Herein, a new coarse-grained methodology for modeling and simulations of polyelectrolyte systems using implicit solvent ionic strength (ISIS) with dissipative particle dynamics (DPD) is presented. This ISIS model is based on mean-field theory approximation and the soft repulsive potential is used to reproduce the effect of solvent ionic strength. The capability of the ISIS model is assessed via two test cases: dynamics of a single long polyelectrolyte chain and the self-assembly of polyelectrolyte diblock copolymers in aqueous solutions with variable ionic strength. The results are in good agreement with previous experimental observations and theoretical predictions, which indicates that our polyelectrolyte model can be used to effectively and efficiently capture salt-dependent conformational features of large-scale polyelectrolyte systems in aqueous solutions, especially at the salt-dominated regime.

ENDS

© Scoop Media

 
 
 
 
 
Business Headlines | Sci-Tech Headlines

 

Sky City : Auckland Convention Centre Cost Jumps By A Fifth

SkyCity Entertainment Group, the casino and hotel operator, is in talks with the government on how to fund the increased cost of as much as $130 million to build an international convention centre in downtown Auckland, with further gambling concessions ruled out. The Auckland-based company has increased its estimate to build the centre to between $470 million and $530 million as the construction boom across the country drives up building costs and design changes add to the bill.
More>>

ALSO:

RMTU: Mediation Between Lyttelton Port And Union Fails

The Rail and Maritime Union (RMTU) has opted to continue its overtime ban indefinitely after mediation with the Lyttelton Port of Christchurch (LPC) failed to progress collective bargaining. More>>

Earlier:

Science Policy: Callaghan, NSC Funding Knocked In Submissions

Callaghan Innovation, which was last year allocated a budget of $566 million over four years to dish out research and development grants, and the National Science Challenges attracted criticism in submissions on the government’s draft national statement of science investment, with science funding largely seen as too fragmented. More>>

ALSO:

Scoop Business: Spark, Voda And Telstra To Lay New Trans-Tasman Cable

Spark New Zealand and Vodafone, New Zealand’s two dominant telecommunications providers, in partnership with Australian provider Telstra, will spend US$70 million building a trans-Tasman submarine cable to bolster broadband traffic between the neighbouring countries and the rest of the world. More>>

ALSO:

More:

Statistics: Current Account Deficit Widens

New Zealand's annual current account deficit was $6.1 billion (2.6 percent of GDP) for the year ended September 2014. This compares with a deficit of $5.8 billion (2.5 percent of GDP) for the year ended June 2014. More>>

ALSO:

Still In The Red: NZ Govt Shunts Out Surplus To 2016

The New Zealand government has pushed out its targeted return to surplus for a year as falling dairy prices and a low inflation environment has kept a lid on its rising tax take, but is still dangling a possible tax cut in 2017, the next election year and promising to try and achieve the surplus pledge on which it campaigned for election in September. More>>

ALSO:

Job Insecurity: Time For Jobs That Count In The Meat Industry

“Meat Workers face it all”, says Graham Cooke, Meat Workers Union National Secretary. “Seasonal work, dangerous jobs, casual and zero hours contracts, and increasing pressure on workers to join non-union individual agreements. More>>

ALSO:

Get More From Scoop

 
 
Standards New Zealand

Standards New Zealand
 
 
 
 
 
 
 
 
Sci-Tech
Search Scoop  
 
 
Powered by Vodafone
NZ independent news