Ion mediated cross-shield driven mucous swelling kinetics

TL;DR

This study develops a bi-phasic ionic gel model to predict and compare the viscoelastic properties of healthy and cystic fibrosis mucus, highlighting the role of Donnan forces in mucus swelling dynamics.

Contribution

The paper introduces a multi-species ionic gel model calibrated with experimental data to analyze mucus swelling mechanisms, emphasizing the impact of ionic interactions and pH.

Findings

Donnan forces dominate mucus swelling transitions

Swelling can be continuous or discontinuous based on ionic conditions

Model accurately predicts differences between healthy and infected mucus

Abstract

We present an experimentally guided, bi-phasic, multi-species ionic gel model to compare and make quantitative predictions on the viscoelastic properties of healthy mucus versus Cystic-Fibrosis infected mucus. The mixture theory consists of the mucus (polymer phase) and water (solvent phase) as well as several different ions: H$^+$, Na$^+$, Cl$^-$ and Ca$^{2+}$. The model is calibrated with the experimental data of mucus diffusivities. Numerical studies reveal that the Donnan forces are the dominating mechanism driving the mucus swelling/deswelling transition. However, these transitions could be continuous or discontinuous, depending on the complex interplay between ionic bath concentrations, pH, polymer mass in the solvent and the average charge per monomer.