Fischell Department of Bioengineering Theses and Dissertations
Permanent URI for this collectionhttp://hdl.handle.net/1903/6628
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Item SPRAYABLE, BIODEGRADABLE POLYMER BLENDS FOR TISSUE ADHESION(2019) Daristotle, John L; Kofinas, Peter; Bioengineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Tissue adhesive materials can revolutionize surgical procedures, but they are often difficult to apply safely because of a required curing step where the viscous components of a glue solidify and become sticky. To simplify their deposition and improve their usability, this dissertation introduces tissue adhesive polymer blends that can be sprayed using a fiber production technique called solution blow spinning. The polymer blends studied here are innovative because they are non-curing: the polymer accumulates as a solid material directly on the tissue substrate of interest during spraying, quickly forming a strong bond. To achieve a rapid increase in tissue adhesion, we developed a surgical sealant composed of poly(lactic-co-glycolic acid) and poly(ethylene glycol) (PLGA/PEG) that becomes adhesive in response to warming to body temperature. We then evaluated PLGA/PEG in small and large animal models of intestinal anastomosis and partial thickness skin wounds. Additional improvements to hemostasis, flexibility, and adhesion were made by incorporating micron-sized silica particles, which produced textured fibers with suppressed crack formation. We also developed the first pressure-sensitive tissue adhesive by formulating elastomeric copolymer blends with two components of different molecular weights. An additional objective of this dissertation was to study sprayable polymers that can be used as a controlled release system for various drugs. Towards this goal, we incorporated antimicrobial silver into solution blow spun PLGA/PEG fibers. At the optimal concentration, silver ions released over 14 days at levels that were effectively antimicrobial with minimal cytotoxicity. Coating strategies for controlling the delivery of polyelectrolyte complexes were also investigated.Item Colorimetric Nanoparticles for Biosensing(2014) Rwego, Kankindi; Kofinas, Peter; Bioengineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Title of Thesis: COLORIMETRIC NANOPARTICLES FOR BIOSENSING Kankindi Rwego, Master of Science, 2014 Thesis directed by: Professor Peter Kofinas Department of Bioengineering In order to develop biosensors that change color upon the detection of a pathogen, nearly monodisperse polymer nanoparticles that can arrange into an ordered lattice structure that emits structural color, which is color free of pigment, or dye are synthesized. This work investigates methods for preparing electrostatically stabilized lattice structures by investigating the co-polymerization of polystyrene latex particles with the ionic co-monomer sodium-2-acrylamido-2-methylpropane sulfonate ("AMPS") through varying emulsion polymerization reaction parameters. Additionally, this work is the first to deposit polystyrene-co-poly(N, N-dimethylacrylamide) core-shell nanoparticles onto a glass substrate, entrap in an elastomer matrix, and successfully show color change from green to red in less than 30 seconds upon exposure to a non-polar solvent. As such, the ability to induce a color change that is observable by the unaided human eye has been established. Therefore, this thesis promises to lead to the development of colorimetric biosensors in the near future.