Martini 3 Coarse-Grained Model for Chitosan with Tunable Acetylation.

Area of Science:

• Biomaterials Science
• Computational Chemistry
• Polymer Science

Background:

• Chitosan, a versatile polysaccharide, finds applications in biomedicine, food packaging, and environmental remediation.
• Variability in chitosan's composition due to incomplete deacetylation complicates structure-property relationship studies.
• Atomistic molecular simulations are crucial for understanding chitosan but are computationally intensive.

Purpose of the Study:

• To develop a coarse-grained model for simulating chitosan, chitin, and their intermediate forms.
• To accurately capture variations in the degree of acetylation and protonation states.
• To enable efficient simulations of chitosan in complex biological and chemical environments.

Main Methods:

• Developed a coarse-grained model compatible with the Martini 3 force field.
• The model accounts for varying degrees of acetylation and protonation states.
• Validated the model by reproducing key structural properties and interactions.

Main Results:

• The model accurately simulates fully deacetylated chitosan, chitin, and intermediate forms.
• Reproduces chitosan's structural properties in solution and its pH-dependent self-assembly.
• Distinguishes chitosan's affinities for zwitterionic and anionic lipids and its interactions with proteins.

Conclusions:

• The developed coarse-grained model is a robust tool for simulating chitosan.
• Facilitates understanding of chitosan's behavior in diverse environments.
• Aids in the rational design of chitosan-based drug and vaccine delivery systems.