Multiscale Mechanics of Calcium-Mediated Reinforcement within a Pectin-Cellulose Composite via Integrated MD and...

Area of Science:

• Biomaterials Science
• Plant Biology
• Materials Science

Background:

• Plant primary cell walls (PCWs) comprise cellulose and pectin, crucial for dynamic growth and structural transitions.
• A complete understanding of the pectin-cellulose interface and calcium ion interactions is vital for developing bioinspired composites.

Purpose of the Study:

• To investigate the cellulose-nanocrystal (CNC)-pectin interface and calcium ion-mediated cross-linking mechanisms.
• To integrate molecular dynamics (MD) simulations with spectroscopic and viscosity measurements for a comprehensive analysis.

Main Methods:

• Multiscale investigation using MD simulations.
• Experimental validation through spectroscopic studies (Raman, FTIR) for molecular interactions.
• Viscosity measurements for bulk property analysis.

Main Results:

• MD simulations identified both "zipper" and "egg-box" cross-linking mechanisms, with "zipper" being dominant (nearly 10x).
• The "zipper" model, driven by Ca2+ coordinating with carboxyl groups, showed less sensitivity to Ca2+ concentration.
• Spectroscopic data confirmed MD findings, showing shifts in carboxylate peaks and hydroxyl group trends.
• MD-predicted viscosity aligned with experimental bulk properties.

Conclusions:

• The study elucidates Ca2+-mediated CNC-pectin interactions, resolving experimental discrepancies.
• Identified dominant "zipper" cross-linking mechanism provides fundamental knowledge on pectin-calcium interactions.
• Offers design guidelines for advanced pectin-based biocomposites for applications in regenerative medicine and flexible robotics.