Abstract
Volume phase transitions in polyeletrolyte gels play important roles in many biophysical processes such as DNA packaging, nerve excitation, and cellular secretion. The swelling and deswelling of these charged polymer gels depend strongly on their ionic environment. In this paper, we present an extension to our previous two-fluid model for ion-binding-mediated gel swelling. The extended model eliminates the assumptions about the size similarity between the network and solvent particles, which makes it suitable for investigating of a large family of biologically relevant problems. The model treats the polyeletrolyte gel as a mixture of two materials, the network and the solvent. The dynamics of gel swelling is governed by the balance between the mechanical and chemical forces on each of these two materials. Simulations based on the model illustrate that the chemical forces are significantly influenced by the binding/unbinding reactions between the ions and the network, as well as the resulting distribution of charges within the gel. The dependence of the swelling rate on ionic bath concentrations is analyzed and this analysis highlights the importance of the electromigration of ions and the induced electric field in regulating gel swelling.
Highlights
Mucus is an entangled network of long-chain glycoproteins that is present in many biological systems including the respiratory and gastrointestinal tracts [1]
The goal of this work is threefold: (1) to re-derive the equations of motion for a model of a mucus-like polyelectrolyte gel based on the work of Sircar et al without the assumption that network and solvent particles are of similar size, (2) to formulate the model in terms of a balance of force densities acting on the network and solvent phases, for clarity, and (3) to simulate and analyze a set of numerical experiments in which a dense sample of mucus, with a high concentration of calcium, is placed into a bath, in which monovalent sodium ions far outnumbered divalent calcium ones, and is allowed to swell dynamically
Our model accounts for the differing chemical affinities of the network polymers for various mono- and divalent ions, and the way in which this chemistry impacts the various forces that govern the dynamics of swelling of the gel
Summary
Mucus is an entangled network of long-chain glycoproteins that is present in many biological systems including the respiratory and gastrointestinal tracts [1]. The goal of this work is threefold: (1) to re-derive (from first principles) the equations of motion for a model of a mucus-like polyelectrolyte gel based on the work of Sircar et al without the assumption that network and solvent particles are of similar size, (2) to formulate the model in terms of a balance of force densities acting on the network and solvent phases, for clarity, and (3) to simulate and analyze a set of numerical experiments in which a dense sample of mucus, with a high concentration of calcium, is placed into a bath, in which monovalent sodium ions far outnumbered divalent calcium ones, and is allowed to swell dynamically. We can understand the dynamic movement of the network/solvent phases as being driven by the three electrochemical force densities, while the mechanical forces arise in response to the motion of the two phases
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
