Biomedical Engineering ETDs

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In this work the development, synthesis, and characterization of biodegradable synthetic polymers, poly (butylene fumarate) (PBF) and the copolymer poly (butylene fumarate)-co-(butylene maleate) (PBFcBM) is described. The unsaturated linear polyesters were synthesized via two synthetic routes, including an acid catalyzed transesterification reaction of (Z)-4-((4-hydroxybutan-2-yl)oxy)-4-oxobut-2-enoic acid which was formed via a ring opening reaction of maleic anhydride with 1,3-butylene glycol (BG) and reacting the acid chlorides, maleoyl chloride (MCl) and fumaryl chloride (FCl) with BG. Both methods introduce the cis (maleate) functionality into the polymer backbone, however a controlled fumarate to maleate ratio was only obtained via the acid chloride starting monomers. The PBF polymer differs from the previously examined PPF polymer through an additional methylene (CH2) unit in the polymer backbone. This methylene unit increases the chain length between the crosslinkable fumarate (C=C) double bond. Because of this, It was hypothesized that PBF allow for a greater water ingress and therefore an increased rate of degradation relative to PPF. Results from In vitro accelerated degradation studies confirmed our hypothesis. An in vitro cytocompatibility study with the murine cell line MC3T3-E1 demonstrated that there were no cytotoxic components that leached from crosslinked PBF networks. In addition, the PBF crosslinked networks were assessed for the ability to support mesenchymal stem cell (MSC) differentiation down the osteogenic lineage. Cellular adhesion and proliferation as well as the presence of alkaline phosphatase and extracellular calcium of MSCs cultured under osteogenic medium conditions on crosslinked PBF networks were evaluated. Methodology to fabricate highly interconnected porous mats comprised of nano to micro sized fibers was developed using the photo initiator bis(2,4,6-trimethybenzoyl) phenoylphosphine oxide (BAPO) to crosslink the fumarate-based fibers in situ while electrospinning. Characterization showed that the alterations to the general electrospinning technique could be used to spin polymers with glass transition (Tg) temperatures below room temperature without the use of a sacrificial polymer.




biomaterials, tissue engineering, polymer chemistry

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Degree Name

Biomedical Engineering

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Department Name

Biomedical Engineering