Document Detail

Ions in mixed dielectric solvents: density profiles and osmotic pressure between charged interfaces.
MedLine Citation:
PMID:  19338312     Owner:  NLM     Status:  MEDLINE    
The forces between charged macromolecules, usually given in terms of osmotic pressure, are highly affected by the intervening ionic solution. While in most theoretical studies the solution is treated as a homogeneous structureless dielectric medium, recent experimental studies concluded that, for a bathing solution composed of two solvents (binary mixture), the osmotic pressure between charged macromolecules is affected by the binary solvent composition. By adding local solvent composition terms to the free energy, we obtain a general expression for the osmotic pressure, in planar geometry and within the mean-field framework. The added effect is due to the permeability inhomogeneity and nonelectrostatic short-range interactions between the ions and solvents (preferential solvation). This effect is mostly pronounced at small distances and leads to a reduction in the osmotic pressure for macromolecular separations of the order 1-2 nm. Furthermore, it leads to a depletion of one of the two solvents from the charged macromolecules (modeled as planar interfaces). Lastly, by comparing the theoretical results with experimental ones, an explanation based on preferential solvation is offered for recent experiments on the osmotic pressure of DNA solutions.
Dan Ben-Yaakov; David Andelman; Daniel Harries; Rudi Podgornik
Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Intramural; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  The journal of physical chemistry. B     Volume:  113     ISSN:  1520-6106     ISO Abbreviation:  J Phys Chem B     Publication Date:  2009 Apr 
Date Detail:
Created Date:  2009-04-23     Completed Date:  2009-06-19     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  101157530     Medline TA:  J Phys Chem B     Country:  United States    
Other Details:
Languages:  eng     Pagination:  6001-11     Citation Subset:  IM    
Raymond and Beverly Sackler School of Physics and Astronomy, Tel Aviv University, Ramat Aviv, Tel Aviv 69978, Israel.
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MeSH Terms
Alcohols / chemistry*
DNA / chemistry
Ions / chemistry
Macromolecular Substances / chemistry
Osmotic Pressure
Solvents / chemistry
Surface Properties
Water / chemistry*
Reg. No./Substance:
0/Alcohols; 0/Ions; 0/Macromolecular Substances; 0/Solvents; 7732-18-5/Water; 9007-49-2/DNA

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