Biologically Inspired Surface Design using Chemical Vapor Deposition Polymerization.

Abstract

Chemical vapor deposition (CVD) of reactive polymer coatings is an ideal technique for surface functionalization, modification and encapsulation. In this dissertation, surface designs for four different biomedical application areas based on the CVD polymerization platform are presented. Precision immobilization strategies for surface tethering multiple biomolecules are discussed in Chapter 2. Orthogonal immobilization strategies are developed based on orthogonally functionalized multipotent polymer coatings. Three specific studies are included in this chapter. Highly efficient and orthogonal bioconjugation reactions are employed, including the alkyne-azide “click” reaction, the hydrazide-aldehyde reaction and the active ester-amine reaction. For potential biosensor development, metal enhanced fluorescence on reactive CVD polymer coated gold films is studied and presented in Chapter 3. Functional CVD polymer coatings with nanoscale thicknesses are used as spacer layers and the surface enhanced fluorescence effect is demonstrated. The fluorescence intensity oscillates with the polymer spacer layer thickness, ranging from highly enhanced (up to 18 fold compared to the polymer coated glass) to completely turn-off. Chapter 4 reports for the first time a method for synthesizing biodegradable CVD polymer films. Degradability is an essential requirement for tissue engineering and other biomedical applications. Degradable CVD polymer films with ester groups in the polymer backbone have not been reported before. They combine the benefits of the CVD coatings with complete degradability. Functional groups can also be introduced into the degradable polymer structure. Two different studies are presented in Chapter 5 to exemplify the applications of reactive CVD polymer coatings on complex structures and integrated devices. The first study describes a two-step CVD method for fabrication of hierarchical polymer-coated carbon nanotube microstructures with tunable mechanical properties and accessible chemical functionality. Ultrasmall implantable composite microelectrodes with functional CVD coatings for chronic neural recordings are presented as the second example. These studies demonstrate easy integration of the CVD polymer coating into micro- or nano- device fabrications. The CVD coatings not only provide desired chemical composition changes to the surface, but also improve mechanical and electrical properties of the integrated structures and devices. In summary, the vapor-based reactive/functional polymer coatings provide a powerful platform for biointerface design and research.