Coarse-grain model for natural cellulose fibrils in explicit water

Area of Science:

• Biophysics
• Materials Science
• Computational Chemistry

Background:

• Understanding cellulose structure is crucial for cellulosic biofuel development.
• Previous models often used implicit solvents, potentially oversimplifying cellulose behavior.
• Accurate modeling requires accounting for solvent interactions.

Purpose of the Study:

• Develop a constraint-free coarse-grain (CG) model for cellulose fibrils in explicit water.
• Investigate the impact of explicit solvent on cellulose fibril structure and dynamics.
• Compare results with implicit solvent models.

Main Methods:

• Developed a CG model for molecular dynamics (MD) simulations of cellulose fibrils.
• Used a coupling parameter (λ) to generate structures ranging from crystalline to amorphous.
• Analyzed structural parameters like root-mean-square deviation and persistence length.

Main Results:

• The crystalline-to-amorphous transition occurs at λ ≈ 0.386.
• Explicit water shifts the transition to higher λ values compared to implicit models.
• Cellulose-water interactions significantly influence the crystalline-amorphous transition.

Conclusions:

• Explicit solvent presence is vital for accurately modeling cellulose fibril structure.
• The new CG model provides a versatile approach for generating diverse cellulose structures.
• This method enhances large-scale lignocellulosic biomass modeling for biofuel applications.