Development of a Coarse-Grained Model of Chitosan for Predicting Solution Behavior

Abstract

A new coarse-grained (CG) model of chitosan has been developed for predicting solution behavior as a function of degree of acetylation (DA). A multiscale modeling approach was used to derive the energetic and geometric parameters of this implicit-solvent, CG model from all-atom simulations of chitosan and chitin molecules in explicit water. The model includes representations of both protonated d-glucosamine (GlcN(+)) and N-acetyl-d-glucosamine (GlcNAc) monomers, where each monomer consists of three CG sites. Chitosan molecules of any molecular weight, DA, and monomer sequence can be built using this new CG model. Discontinuous molecular dynamics simulations of chitosan solutions show increased self-assembly in solution with increasing DA and chitosan concentration. The chitosan solutions form larger percolated networks earlier in time as DA and concentration increase, indicating "gel-like" behavior, which qualitatively matches experimental studies of chitosan gel formation. Increasing DA also results in a greater number of monomer-monomer associations, which has been predicted experimentally based on an increase in the storage modulus of chitosan gels with increasing DA. Our model also gives insight into how the monomer sequence affects self-assembly and the frequency of interaction between different pairs of monomers.

Scrolling of Supramolecular Lamellae in the Hierarchical Self-Assembly of Fibrous Gels

“…Provided the system is well-parameterized and the force field carefully chosen, MD simulations can replicate the key results of more realistic but computationally expensive calculation techniques. MD studies have been used to map the self-assembly pathways of peptides, [37][38][39] lipids, 40,41 and polysaccharides, 42 as well as generalized polymers, [43][44][45] rod-shaped molecules, 46,47 and colloidal particles. 48,49 Simulations have captured the formation of experimentally observable structures such as b sheets, cylindrical micelles, and phospholipid bilayers and provided realistic illustrations of their interactions with solvents, ions, and biologically relevant additives.…”

An accurate coarse-grained model for chitosan polysaccharides in aqueous solution

“…Different strategies for the parametrization of bottom-up CG models for different polysaccharides, which preserve as much chemical detail of the atomistic system as possible have been pursued in the past [24–27]. In addition, the popular top-down MARTINI CG model [28–30] has recently been extended to include parameters specifically for modeling the α -Chitin [31] crystal and for GlcNac and [32] monomers, which have been used to model chitosan self assembly with discontinuous molecular dynamics simulations.…”

Specific Features of Structure, Electrical Conductivity and Interlayer Adhesion of the Natural Polymer Matrix from the Layers of Branched Carbon Nanotube Networks Filled with Albumin, Collagen and Chitosan

“…The total structure weight in this system is~10313.984 g/mol. The coarse-grained structure of chitosan was obtained using the model by Benner and Hall [37]. The number of beads in the coarse-grained representation of chitosan is 704.…”

“…If these parameters stabilized in time and did not change, then the complex reached an equilibrium and energetically favorable configuration. Next, we investigated three types of natural polymer matrix, representing a carbon framework with filler as a human albumin protein [36], with collagen [33] and with chitosan [37]. In all cases, the trigonal coarse-grained model of the carbon framework constructed by us and coarse-grained natural polymer models constructed using data from a protein database (PDB) and MARTINI model were used.…”