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School of Biomedical Engineering

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These digital collections include theses, dissertations, and faculty publications from the School of Biomedical Engineering.

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Browsing School of Biomedical Engineering by Author "Bui, Hieu T., author"

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    The development of hyaluronan enhanced expanded polytetrafluoroethylene and linear low density polyethylene for blood contacting applications
    (Colorado State University. Libraries, 2019) Bui, Hieu T., author; James, Susan, advisor; Reynolds, Melissa, committee member; Popat, Ketul, committee member; Olver, Christine, committee member
    Cardiovascular disease is the number one cause of death in high income, industrialized countries. Designing cardiovascular implants from synthetic polymers is a cost-effective solution to the growing demand for medical treatments such as heart valve replacements and cardiovascular bypass procedures. Synthetic polymers are often known for their tunability, durability, and low production cost. Unfortunately, these materials are also prone to induce thrombosis. Therefore, improving the blood compatibility of these polymers is still a major challenge in the biomedical field. This dissertation discusses the alteration of two synthetic polymers, linear low density polyethylene (LLDPE) and expanded polytetrafluoroethylene (ePTFE), using hyaluronan (HA) to improve their blood compatibility. HA, a naturally occurring polysaccharide in the human body, is known for its wound healing and anticoagulant properties. In this work, two unique methods were developed for HA enhancement of ePTFE (HA-ePTFE) and LLDPE (HA-LLDPE). This was a process driven research that aimed at designing HA-ePTFE and HA-LLDPE by analyzing the effect of different treatment parameters on the properties of the resultant materials. In the case of ePTFE, it was demonstrated that HA can be incorporated into vascular ePTFE grafts by exploiting the micro pores of the polymer and adjusting the spraying treatment. In the HA-LLDPE fabrication process, its parameters were varied to assess their effects on the interpenetrating polymer network (IPN) formation. Surface characterization such as water contact angle goniometry, infrared spectroscopy, and toluidine blue O (TBO) staining prove that HA treatment successfully changed the surface chemistry and increased the hydrophilicity of ePTFE and LLDPE. Thermal analysis and gas chromatography-mass spectrometry were used to quantify the effects of different treatment conditions on material properties. Tensile properties such as elastic modulus, tensile strength, yield stress and ultimate strain are unchanged by HA enhancement for both polymers. The biological results reveal that HA-ePTFE and HA-LLDPE are not cytotoxic and result in less blood clotting and platelet activation than ePTFE and LLDPE.