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Glycopolymers and Glyconanomaterials for Biomedical and Environmental Applications
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- Author / Creator
- Wang, Yinan
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Protein–carbohydrate interactions are involved in a wide variety of cellular recognition processes including cell growth regulation, differentiation and adhesion, immune response, and viral or bacterial infections. Recently, utilization of carbohydrate based polymers and nanomaterials for various biomedical or environmental applications has emerged as an important topic as a result of the better understanding of the critical role of carbohydrates play in those applications. In this thesis, a review on glycopolymer synthesis as well as the applications of the glycopolymers in biomedical and environmental applications is first presented followed by the studies on using glycopolymers modified quartz crystals microbalance with dissipation (QCM-D) to probe bacterial adhesion mediated by the carbohydrate-protein interactions. The results showed Pseudomonas aeruginosa (P. aeruginosa) PAO1 bearing galactose-specific binding lectin (PA-IL) can bind to the galactose containing glycopolymer surface stronger as compared to Escherichia coli (E. coli) K-12 (a Gram-negative bacterium with mannose-specific binding lectin) adhesion on the same surface. The presence of divalent ions, such as calcium, was also found to play an important role on bacterial adhesion events, as the ions can coordinate specific amino acid residues at the carbohydrate recognition domain and allow lectins to specifically bind the hydroxyl groups of sugars. Temperature responsive poly(N-isopropylacrylamide) [P(NIPAAm)] homopolymers and copolymers (consisting of a few sugar residues) were synthesized by a one-pot reversible addition–fragmentation chain transfer (RAFT) polymerization and subsequently immobilized on QCM-D to generate biomimetic surfaces to study the two major bacterial infection mechanisms: hydrophobic and lectin–carbohydrate interactions. Although, a greater number of P. aeruginosa adhered to the NIPAAm homopolymer modified surfaces at temperatures higher than the lower critical solution temperature (LCST), the bacterium–substratum bond stiffness was stronger between P. aeruginosa and a galactose based P(NIPAAm) surface. These observations might suggest that both hydrophobic and lectin–carbohydrate interactions contribute to bacterial adhesion on cell surfaces, while the latter plays a significant role in bacterial infections. By exploiting the carbohydrate-protein interactions, a dual pH and glucose responsive glycopolymers modified boronic acid containing nanofiber was designed for the reversible capture and release of lectins. By immobilizing glycopolymers carrying different types of sugar residues such as glucose and galactose on the nanofiber surface, the resulting nanofibers can selectively capture lectins under alkaline conditions. On the other hand, treatment of the modified nanofibers with an acidic or glucose solution resulted in the detachment of both lectins and glycopolymers from the nanofiber surface. These functional nanofibers can therefore be easily modified and hence can be used for quick removal of selective proteins or toxins from the solution. In conclusion, glycopolymers are ideal candidates for understanding of various biological events or materials design for various applications. Some interesting future directions for the glycopolymers based materials are also proposed at the end of this thesis.
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- Graduation date
- Spring 2016
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- Type of Item
- Thesis
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- Degree
- Doctor of Philosophy
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- License
- This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.