Thesis
Molecular dynamics simulations of chitosan oligomer interactions at surfaces and lipid bilayers
- Creator
- Rights statement
- Awarding institution
- University of Strathclyde
- Date of award
- 2024
- Thesis identifier
- T17177
- Person Identifier (Local)
- 202081886
- Qualification Level
- Qualification Name
- Department, School or Faculty
- Abstract
- Chitin and chitosan (de-acetylated chitin) biopolymers, derived mainly from langoustine shell waste, are excellent candidates for novel antimicrobial applications. Despite the large body of literature concerning chitosan, there is a need for further characterisation of chitosan dynamics at aqueous interfaces to aid the design of novel composite materials. In this thesis, fully atomistic molecular dynamics simulations have been developed to study chitin and chitosan oligomer interactions with α-chitin and silica surfaces using umbrella sampling. The free energy curves yield binding energies of -2.1 and -0.33 kcal mol−1 per monomer for chitin and uncharged chitosan oligomers on chitin, and -0.6 kcal mol−1 per monomer for a charged chitosan oligomer on silica at pH 5. This means that the adsorbed chitosan oligomers are mobile on both surfaces. It is found that chitin and chitosan binding to the chitin surface is driven by hydrogen bonding, where the strength for chitosan is reduced by its lack of the acetyl group. In contrast, charged chitosan binding to silica is dominated by electrostatics, with the loading capacity of 0.094 mg m−2 reflecting charge compensation. This can be controlled by the choice of ionic solution, which has technological implications. Lastly, the interaction of chitosan with a complex model gram negative bacterial membrane was studied to further understanding of chitosan’s antimicrobial activity. It was found that chitosan only weakly interacts with the lipopolysaccharides that form the outermost layer of the E. coli cell envelope, while readily adsorbing to the inner membrane. This is a novel finding, as most of the current research focuses on chitosan interaction with the inner membrane, neglecting to explain chitosan diffusion through the outer membrane. The findings presented in this thesis can be used to guide the experimental design of chitosan-coated silica nanoparticles and chitosan-chitin composite materials for applications such as drug delivery or additives for biopolymer food packaging.
- Advisor / supervisor
- Ferro, Valerie
- Mulheran, Paul
- Johnston, Karen
- Resource Type
- DOI
- Funder
Relations
Items
| Thumbnail | Title | Date Uploaded | Visibility | Actions |
|---|---|---|---|---|
|
|
PDF of thesis T17177 | 2025-01-21 | Public | Download |