Browsing by Author "Wendy Krause, Committee Co-Chair"

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    Hyaluronic Acid-based Nanofibers via Electrospinning
    (2006-12-11) Young, Denice Shanette; Wendy Krause, Committee Co-Chair; Maurice Balik, Committee Co-Chair; Richard Spontak, Committee Member
    Electrospinning is a novel technology that uses an electric field to form fibrous materials from a polymer solution. Unlike traditional spinning techniques, electrospinning can produce fibers, on the order of 100 nm, that can be utilized in applications where nanoscale fibers are necessary for specific applications, including tissue engineering and filtration. Outside of a smaller fiber diameter, electrospun nanofibers are also advantageous for biomedical applications because they have a larger surface area and pore size which promotes cell growth. A number of polymers have been electrospun successfully, including polyethylene (PEO) and polyvinyl chloride (PVC), which are two the most investigated electrospun materials. For the purpose of this study, hyaluronic acid (HA), a widely used biopolymer found in the extracellular matrix, was the chosen polymer to investigate the successful production of HA nanofibers for use in tissue engineering. Few studies have been conducted on electrospinning HA. Indeed, when this project was initiated, no investigations on electrospinning HA had been published. The goal of this research was to produce continuous fibrous strands of HA to be used as a mesh or scaffolding material. The high viscosity and surface tension of HA make it challenging to electrospin, as both are important parameters in successful production of nanofibers. To promote HA fiber formation by electrospinning, the effects of salt (NaCl), which is used to reduce the viscosity of aqueous HA solutions; molecular weight of the HA; and an additional biocompatible polymer (e.g., PEO) were investigated.
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    Keratinocyte and Hepatocyte Growth Proliferation and Adhesion to Helium and Helium/Oxygen Atmospheric Pressure Plasma Treated Polyethylene Terephthalate
    (2006-03-06) Christie, Megan Allison; Mohamed Bourham, Committee Co-Chair; Wendy Krause, Committee Co-Chair; Hechmi Hamouda, Committee Member; Jeffrey Macdonald, Committee Member
    To improve the surface properties of biomaterials, the effects of changes in surface chemistry and morphology of polyethylene terephthalate (PET) films treated with atmospheric pressure plasma were investigated as a function of cellular growth, proliferation, and adhesion. PET films were subjected to helium and helium/oxygen gas plasmas. The contact angle of the treated films decreased due to plasma etching and possible scission indicating that the surfaces become more hydrophilic. Atomic force microscopy results had a large standard error, however the surface visually showed changes in surface micro and nanoscale roughness corresponding to treatment duration. Keratinocytes were plated on the day of plasma treatment and two and five days after plasma treatment and tested half a day, one, two, three, and six days after plating. The same methodology of plating and testing was also applied to hepatocytes. Cell growth, proliferation, and adhesion were characterized via a fluorescent probe based assay and were correlated with surface chemical and nanostructural features. Both the helium and helium/oxygen plasma-treated PET had little or no effect on cell behavior for both keratinocytes and hepatocytes. The nanoscale surface changes due to the plasma surface treatment are believed to be masked by the protein adherence in the media on the surface of the PET.