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Title: Chitosan Molecular Structure as a Function of N-Acetylation

Molecular dynamics simulations have been carried out to characterize the structure and solubility of chitosan nanoparticle-like structures as a function of the deacetylation level (0, 40, 60, and 100%) and the spatial distribution of the N-acetyl groups in the particles. The polysaccharide chains of highly N-deacetylated particles where the N-acetyl groups are uniformly distributed present a high flexibility and preference for the relaxed two-fold helix and five-fold helix motifs. When these groups are confined to a given region of the particle, the chains adopt preferentially a two-fold helix with f and w values close to crystalline chitin. Nanoparticles with up to 40% acetylation are moderately soluble, forming stable aggregates when the N-acetyl groups are unevenly distributed. Systems with 60% or higher N-acetylation levels are insoluble and present similar degrees of swelling regardless the distribution of their N-acetyl groups. Overall particle solvation is highly affected by electrostatic forces resulting from the degree of acetylation. The water mobility and orientation around the polysaccharide chains affects the stability of the intramolecular O3- HO3(n) ... O5(n+ 1) hydrogen bond, which in turn controls particle aggregation.
Authors:
; ;
Publication Date:
OSTI Identifier:
1026589
DOE Contract Number:
AC05-76RL01830
Resource Type:
Journal Article
Resource Relation:
Journal Name: Biopolymers, 95(7):448 - 460; Journal Volume: 95; Journal Issue: 7
Research Org:
Pacific Northwest National Laboratory (PNNL), Richland, WA (US), Environmental Molecular Sciences Laboratory (EMSL)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
08 HYDROGEN; ACETYLATION; CHAINS; CHITIN; DISTRIBUTION; ELECTROSTATICS; FLEXIBILITY; HYDROGEN; MOLECULAR STRUCTURE; ORIENTATION; POLYSACCHARIDES; SOLUBILITY; SOLVATION; SPATIAL DISTRIBUTION; STABILITY; SWELLING; WATER Environmental Molecular Sciences Laboratory