Molecular mechanisms of the structures, interactions, and mechanical properties of methacrylate-modified gellan gum

Gellan gum is a highly biocompatible and mechanically tunable material for tissue engineering applications. Upon modification with N-succinimidyl methacrylate, gellan gum forms a photocrosslinkable hydrogel. Specifically, increasing concentration and the degree of methacrylate substitution strengthen both the mechanical properties and biological characteristics. In this study, we employed molecular dynamics simulations to investigate how concentrations and degrees of methacrylate substitution affect the molecular structure, interactions, and mechanical properties of methacrylate-modified gellan gum. Both unmodified and methacrylate-modified gellan gum chains adopted relatively extended conformations. However, higher concentrations favored denser, entangled structures. Increasing the methacrylate substitution from 16.7 % to 33.3 % promoted steric effects that reduced chain folding, yielding more extended conformations, and thus enhanced the mechanical property. At 50 % methacrylate substitution, the strong methacrylate interactions and increased crosslink density led to recoiled conformations, reduced load-transfer efficiency, and decreased mechanical performance. Hydrogen bonding analysis revealed that higher substitution increased intramolecular hydrogen bonding but reduced intermolecular interactions, especially at higher concentrations. These findings highlight the balance between molecular conformation, crosslinking density, and hydrogen bonding in determining the mechanical behavior of gellan gum. The results provide a molecular-level design mechanism for tuning methacrylate substitution to achieve desired properties in biomedical hydrogels for bioengineering applications.