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Multifunctional Self-Healing Hydrogels Based on Natural Polymers for Biomedical Applications
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- Author / Creator
- Huang, Weijuan
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Hydrogel is a chemically or physically cross-linked hydrophilic three-dimensional (3D) polymer network. Classic hydrogels with irreversibly cross-linked polymer networks cannot heal after rupture, leading to degradation and deterioration in their functions over time. In contrast, self-healing hydrogels could be spontaneously restored after damage, which could extend the longevity. Because self-healing hydrogels from synthetic chemicals generate environmental issues, self-healing hydrogels from natural polymers would be more desirable. Chitosan is a cationic polysaccharide derived from the partial deacetylation of chitin, which is the main constituent of exoskeleton of crustaceans (e.g. shrimp, lobster, crayfish, and crab) and is the second abundant natural polysaccharide after cellulose on the earth. Besides its abundance, chitosan also possesses many superior physicochemical and biological properties, which is the ideal precursor to fabricate hydrogels. One major challenge is that self-healing hydrogels based on reversible interactions usually exhibit poor mechanical properties and slow self-healing process. In addition, most self-healing hydrogels could only heal under harsh conditions such as high temperature and low pH. Consequently, there is a demand for the development of new natural polymers-based self-healing hydrogels, which could quickly self-heal under physiological conditions and possess good mechanical strength.
This research developed carboxymethyl chitosan (CMC) based self-healing hydrogels by crosslinking with benzaldehyde-terminated four-arm polyethylene glycol (PEG-BA) and dialdehyde cellulose nanocrystals (DACNC). Both the CMC/PEG-BA and CMC/DACNC hydrogels exhibited good mechanical strength and rapidly healed within 5 min at room temperature without external stimuli. Afterwards, a second network crosslinked through covalent bonds were introduced to the chitosan based self-healing network to increase their stretchability and toughness. Furthermore, chitosan were grafted with catechol moieties and crosslinked with DACNC to construct self-healing hydrogels with bioadhesive capacity. The three-dimensional (3D) cell encapsulation demonstrated that the hydrogel possessed excellent cytocompatibility and could be used for 3D cell culture. In vivo tests indicated that the hydrogels could be employed as non-compressive hemostatic material and be injected to internal tissues (e.g. liver) to rapidly and effectively stop massive hemorrhage. In addition, the self-healing hydrogels could be precisely injected to irregular and deep injuries to fully cover the wound beds, and then be painlessly removed by on-demand dissolving using amino acid solution, which prevented complex surgical procedures. The self-healing hydrogels have been used as deep partial thickness burn wound dressing to facilitate burn healing with reduced scar formation.
This research opens up novel pathways to fabricate self-healing hydrogels with desired properties including facile to prepare and use, rapid self-healing, high mechanical strength and strong tissue adhesive capacity. These benefits support their potential applications in biomedical field, such as 3D cell encapsulation, hemostasis and wound healing. -
- Graduation date
- Fall 2019
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- Type of Item
- Thesis
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- Degree
- Doctor of Philosophy
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- License
- Permission is hereby granted to the University of Alberta Libraries to reproduce single copies of this thesis and to lend or sell such copies for private, scholarly or scientific research purposes only. Where the thesis is converted to, or otherwise made available in digital form, the University of Alberta will advise potential users of the thesis of these terms. The author reserves all other publication and other rights in association with the copyright in the thesis and, except as herein before provided, neither the thesis nor any substantial portion thereof may be printed or otherwise reproduced in any material form whatsoever without the author's prior written permission.