Particle transport through hydrogels is charge asymmetric

Xiaolu Zhang, Johann Hansing, Roland R. Netz, Jason E. Derouchey

Research output: Contribution to journalArticlepeer-review

42 Scopus citations

Abstract

Transport processes within biological polymer networks, including mucus and the extracellular matrix, play an important role in the human body, where they serve as a filter for the exchange of molecules and nanoparticles. Such polymer networks are complex and heterogeneous hydrogel environments that regulate diffusive processes through finely tuned particle-network interactions. In this work, we present experimental and theoretical studies to examine the role of electrostatics on the basic mechanisms governing the diffusion of charged probe molecules inside model polymer networks. Translational diffusion coefficients are determined by fluorescence correlation spectroscopy measurements for probe molecules in uncharged as well as cationic and anionic polymer solutions. We show that particle transport in the charged hydrogels is highly asymmetric, with diffusion slowed down much more by electrostatic attraction than by repulsion, and that the filtering capability of the gel is sensitive to the solution ionic strength. Brownian dynamics simulations of a simple model are used to examine key parameters, including interaction strength and interaction range within the model networks. Simulations, which are in quantitative agreement with our experiments, reveal the charge asymmetry to be due to the sticking of particles at the vertices of the oppositely charged polymer networks.

Original languageEnglish
Pages (from-to)530-539
Number of pages10
JournalBiophysical Journal
Volume108
Issue number3
DOIs
StatePublished - Feb 3 2015

Bibliographical note

Funding Information:
This work was supported by start-up funds from the University of Kentucky, the University of Kentucky Research Challenge Trust Fund (RCTF) Fellowship for Biochemistry and by the Deutsche Forschungsgemeinschaft via grants SFB 1112 and GRK1558.

Publisher Copyright:
© 2015 Biophysical Society.

ASJC Scopus subject areas

  • Biophysics

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