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Combined depletion and electrostatic forces in polymer-induced membrane adhesion: a theoretical model
Antonio Raudino1, Martina Pannuzzo, Mikko Karttunen
1Dipartimento di Scienze Chimiche, University of Catania, Viale A. Doria 6-95125, Catania, Italy. araudino@dipchi.unict.it
The Journal of Chemical Physics
|February 11, 2012
Summary
We developed a theory for charged surfaces in polymer solutions, revealing ion-induced depletion forces and polymer-modified repulsion. This adhesion model shows robustness against charge variations.
Area of Science:
- Physical Chemistry
- Materials Science
- Biophysics
Background:
- Adhesion between charged surfaces in physiological-like fluids is complex due to polymer-electrolyte interactions.
- Understanding these interactions is crucial for biological and material systems.
Purpose of the Study:
- To develop a semi-quantitative analytical theory describing adhesion between charged surfaces in polymer-containing electrolyte solutions.
- To validate the theory using coarse-grained Molecular Dynamics (MD) simulations.
Main Methods:
- A self-consistent analytical model combining Poisson-Boltzmann equation, continuum mean-field polymer theory, solvation energy, and surface interaction terms.
- Validation through extensive coarse-grained Molecular Dynamics (MD) simulations.
Main Results:
- High surface charges lead to polymer exclusion from the gap and increased ion concentration.
- The model demonstrates strong coupling between osmotic forces, surface potential, and polymer salting-out effects.
- Identified long-ranged ion-induced polymer depletion forces and polymer-modified repulsive Coulomb forces, both increasing with surface charge density.
Conclusions:
- The developed theory accurately describes adhesion phenomena in polymer-electrolyte systems.
- The system exhibits homeostatic behavior, showing robustness against charge variations.
- The findings highlight differences between monomeric and polymeric solvents in response to Coulombic interactions.
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