Diffusion in Intact Secondary Cell Wall Models of Plants at Different Equilibrium Moisture Content

Daipayan Sarkar, Lintao Bu, Joseph Jakes, Jacob Zieba, Isaiah Kaufman, Michael Crowley, Peter Ciesielski, Josh Vermaas

Research output: Contribution to journalArticlepeer-review

2 Scopus Citations

Abstract

Secondary plant cell walls are composed of carbohydrate and lignin polymers, and collectively represent a significant renewable resource. Leveraging these resources depends in part on a mechanistic understanding for diffusive processes within plant cell walls. Common wood protection treatments and biomass conversion processes to create biorefinery feedstocks feature ion or solvent diffusion within the cell wall. X-ray fluorescence microscopy experiments have determined that ionic diffusion rates are dependent on cell wall hydration as well as the ionic species through non-linear relationships. In this work, we use classical molecular dynamics simulations to map the diffusion behavior of different plant cell wall components (cellulose, hemicellulose, lignin), ions (Na+, K+, Cu2+, Cl) and water within a model for an intact plant cell wall at various hydration states (3–30 wt% water). From these simulations, we analyze the contacts between different plant cell wall components with each other and their interaction with the ions. Generally, diffusion increases with increasing hydration, with lignin and hemicellulose components increasing diffusion by an order of magnitude over the tested hydration range. Ion diffusion depends on charge. Positively charged cations preferentially interact with hemicellulose components, which include negatively charged carboxylates. As a result, positive ions diffuse more slowly than negatively charged ions. Measured diffusion coefficients are largely observed to best fit piecewise linear trends, with an inflection point between 10 and 15% hydration. These observations shed light onto the molecular mechanisms for diffusive processes within secondary plant cell walls at atomic resolution.

Original languageAmerican English
Article number100105
Number of pages10
JournalThe Cell Surface
Volume9
DOIs
StatePublished - Dec 2023

Bibliographical note

Publisher Copyright:
© 2023

NREL Publication Number

  • NREL/JA-2800-85779

Keywords

  • compound middle lamella
  • degree of polymerization
  • molecular dyamics
  • plant cell wall
  • relative humidity
  • X-ray fluorescence microscopy

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