Master of Engineering Science
Musculoskeletal Health Research
Price, Aaron D.
Séguin, Cheryle A.
Areas of large bone loss are typically healed using autologous bone grafts, seen as the gold standard of care. These materials have a complication rate of 10–40% during harvesting and are limited by the quantity available; therefore the use of 3D printed polymer scaffolds as bone graft alternatives are proposed. Polypyrrole (PPy) is a biocompatible electroactive polymer that has metal-like electrical properties that can be harnessed to hold and release charged drug molecules, triggered by a change in pH. pH fluctuations are seen inside the human body in areas of bone regrowth, which would act as the triggering mechanism for drug release from PPy. PPy nanoparticles were incorporated into hydrogel resins, capable of being 3D printed using stereolithography techniques using riboflavin as a natural photoinitiator. Polymers were tested for drug delivery capabilities, cell adhesion, and biocompatibility to ensure proper function. These composite polymers were successful as a potential material for synthetic bone grafts.
Summary for Lay Audience
3D Printing is revolutionizing the manufacturing of medical devices, allowing the production of patient-customized devices with unique shapes. Bioprinting refers to the application of 3D printing alongside the incorporation of cells, growth factors, drug molecules, and biologics to create materials that mimic real tissues. One common bioprinting material is hydrogels, classified as polymers that have a high affinity for water. Hydrogels have been shown they are capable of supporting cell growth but are not perfect and can have improved functionality by pairing them with a second polymer. Polypyrrole was chosen as a copolymer because of its electrical properties as a conjugated polymer, meaning it offers metal-like conductivity in a polymer. These properties give polypyrrole the ability to store and release drug molecules, triggered by surrounding pH changes. Interestingly, there are pH changes seen naturally in areas of bone regrowth or regeneration due to the bone healing cycle. Using polypyrrole in areas on bone regeneration could act as the triggering method for drug release from 3D printed scaffolds. In this study, we used 3D printing to create a hydrogel-polypyrrole scaffold capable of pH-triggered drug delivery while supporting cell growth. The scaffold was tested for drug delivery capabilities, cell adhesion, and biocompatibility to ensure proper function inside the human body. These studies show the success of a 3D printed biocompatible hydrogel-polypyrrole scaffold and could be further investigated as an alternative to bone grafts.
Lawrence, Matthew T., "3D Printed Polypyrrole Scaffolds for pH Dependent Drug Delivery with Applications in Bone Regeneration" (2021). Electronic Thesis and Dissertation Repository. 7837.
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Available for download on Friday, December 31, 2021