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http://hdl.handle.net/11375/27547
Title: | Fabrication of Advanced Organic-Inorganic Coatings Using Biomimetic Colloidal Techniques |
Authors: | Baker, Kayla |
Advisor: | Zhitomirsky, Igor |
Department: | Materials Science and Engineering |
Keywords: | Biomedical;Coatings;Polymer;Bile Acid |
Publication Date: | 2022 |
Abstract: | Surface modifications of bone-interfacing biomedical devices can increase their longevity by promoting bond formation and new bone growth, while reducing the toxic effects of corrosion and wear particles. Coatings which contain biocompatible polymers, bioceramics, drugs, and functional molecules are one route to achieve this. Here, a biomimetic approach is developed for the fabrication of poly(ethyl methacrylate) (PEMA) coatings. For the first time it is shown that PEMA can be solubilized in non-toxic solvents by naturally occurring bile acids. Their unique chemical structure and amphiphilicity allows for efficient solubilization of polymer macromolecules. Advancements in colloidal sciences enable a facile deposition method termed “dip coating” to be utilized. The feasibility of highly concentrated solutions of high molecular mass PEMA was a key factor for film deposition by dip coating. Singular layers or multilayered PEMA films could be deposited. Heat-treated PEMA films provided corrosion protection to stainless steels. This inexpensive and simple technique can be up scaled to larger manufacturing levels, leading to mass production and clinical development of novel coatings for biomedical applications. Additional challenges in the fabrication of composite coatings by dip coating were successfully addressed using bile acids. To produce high quality composite coatings by dip coating, a stable suspension is required. Particle aggregation leads to uneven coatings, poor adhesion, and weakened mechanical properties. It was shown that bile acids could act as dispersing agents to mediate this. PEMA coatings containing inorganic materials hydroxyapatite, silica, titania, and diamond were fabricated. The inorganic component of the films could be increased to 50 wt.%. Model drugs tetracycline and ibuprofen were used for the creation of drug-loaded PEMA coatings. Lastly, composite coatings containing functional molecules including heparin and nanocellulose were created. Overall, these coatings provide corrosion resistance to metallic orthopedic implants, while enhancing potential biocompatibility of the device. The biomimetic approach developed in this investigation was motivated by the role of bile acids and bile salts as solubilizers of cholesterol and other molecules within the digestive system of mammals. A solubilization mechanism has been proposed. This work paves the way for the fabrication of future composite coatings containing other high molecular mass polymers, inorganic nanomaterials, and functional materials or drugs. |
URI: | http://hdl.handle.net/11375/27547 |
Appears in Collections: | Open Access Dissertations and Theses |
Files in This Item:
File | Description | Size | Format | |
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M.A.Sc. Thesis - K. Baker.pdf | 4.26 MB | Adobe PDF | View/Open |
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