Plasma Surface Modifications For Biomedical And Electrical Applications




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Chemistry & Biochemistry


The focus of this work centers on molecular structuring of surfaces. The surface modifications were achieved using plasma polymerization technology, specifically variable duty cycle pulsed plasmas. The results obtained demonstrate that both exacting film chemistry and film thickness control were achieved during deposition of thin polymeric films on selected substrates. The following achievements are detailed in this thesis:* Identification of a new class of volatile monomers which can be successfully used to synthesize thermoresponsive hydrogel films. A unique aspect of this work is that the lower critical solution temperatures of these gels can be controllably varied by simple adjustment of the plasma polymerization deposition conditions. * Successful covalent attachment of proteins and anti-bodies to plasma modified surfaces, including ultrafine particles as small as nanoparticles. In particular, the use of spacer molecules was shown to be effective in tethering the biomolecules to particle surfaces, without compromise of the biological function of the attached biomolecules. * Surfaces were successfully constructed for tissue culture applications, as illustrated with fibroblast and endothelial cells. Significant enhancement in both initial cell surface attachment and subsequent growth were obtained for both cell lines, as achieved by control of surface chemistry and film thickness of the plasma deposited polymers. This is the first study to document the efficacy of combining surface tailoring and film thickness to improve tissue culture growth.* A novel plasma polymerization process was developed to produce layered structures of bipolar films, as achieved by depositing alternate layers of -COOH and -NH2 functionalized films. Polar entities were created by spontaneous proton transfer from -COOH groups to -NH2 functionalities, as documented by detailed spectroscopic characterization of these films. The dielectric constants (κ) of these multilayered structures were found to be in excess of 6, an extremely large value for an all-organic film.A number of potential future applications are briefly identified for the technology developed in this work. Among these future applications are drug delivery, tissue culture, and flexible dielectric films for electronic applications.