Multifunctional Polymer Coatings via Chemical Vapor Deposition Copolymerization.

Abstract

The dissertation investigates how reactive polymer coatings can facilitate controlled immobilization of multiple biomolecules and can control multiple surface properties independently for biomedical applications. Chemical vapor deposition (CVD) copolymerization technology was chosen for the surface modification of substrates and biological devices, due to its high degree of conformal deposition. This feature was evidenced by the conformal deposition of reactive coatings within pre-assembled microfluidic channels, with aspect ratios as high as 37. A superhydrophobic reactive CVD-coated surface was designed. The coating can immobilize proteins, despite its extremely high contact angle (> 155º). Also, multipotent copolymer coatings presenting two different biological ligands in controllable ratios were prepared via CVD copolymerization of two functionalized PCPs. These polymer coatings are designed so that different reactive groups can be orthogonally introduced, making them attractive for a wide range of biomedical devices. Preliminary biocompatibility of these coatings was assessed in short-term experiments (24-48 hr), using human umbilical vein endothelial cells and 3T3 murine fibroblasts. Both cell types adhered and spread on PPX polymers, with limited growth occurring on fluorinated PPX coatings. G6PD assays indicated significantly low cytotoxicity of CVD surfaces, when cultured with fibroblasts. We also demonstrate the immobilization of two different antithrombotic biomolecules onto a CVD-based copolymer via orthogonal immobilization strategies. The antithrombotic biomolecules retained their bioactivity after immobilization. Furthermore, a modified CVD process was used to produce coatings which possess reactive surface composition gradients. The as-deposited gradient compositions range from 85% to 20%. Also, the CVD system can deposit various gradient slopes, such that the same composition range is deposited over distances of 1’’, 3’’, or 6’’. These surface gradients can immobilize two biomolecules as gradients, allowing for further adaptation to specific biological environments. Applications from this dissertation include the development of novel analytical biodevices, tissue engineering protocols, and combinatorial screening platforms. For instance, growth and differentiation of neurons occur along a chemical gradient. CVD copolymer gradients could mimic biological environments to guide their growth. Also, gradient deposition allows for the mass production of many copolymer compositions in one deposition. These samples could then be simultaneously screened for their interactions with cells.