Directing neuronal behavior via polypyrrole-based conductive biomaterials

The objective of my thesis is to explore the use of the conducting polymer, polypyrrole, in neural applications. In addition a supplementary aspect of dissertation will involves understanding the effects of external stimuli on nervous system cells, with the ultimate goal of designing therapeutic systems for nerve regeneration. In normal development and peripheral nervous system repair, nerves encounter naturally occurring chemical, physical, and electrical stimuli. Polypyrrole (PPy) has attracted much attention for use in numerous biomedical applications as it presents chemical, physical and electrical stimuli. In addition, PPy is particularly exciting because the extent by which chemical, physical, and electrical cues are presented to the injured nerve can be easily tailored. Thus, conducting polymers are excellent scaffolds for the exploration of how the cellular components of the nervous system (i.e., Schwann cells and neurons) interact with chemical, topographical, and electrical stimuli. This dissertation covers three main objectives and is supplemented by two additional topics. The two additional topics explore the effect stimuli present on the conducting polymer PPy have on neural interfaces. These fundamental studies use computational modeling to gain a better understanding of cellular motility on substrates containing different stimuli. Both topics are covered in the appendices of this dissertation. With regards to the three main objectives, I first characterized and optimized the electrochemical synthesis of the conducting polymer, PPy, for Schwann cell biocompatibility. Next, I investigated the effect the application of electrical cues through PPy has on Schwann cell migration. In addition to investigating the effect of the direct electrical current on Schwann cells I also considered the effect that electrical stimulation provided by PPy has on protein adsorption. Finally, I developed a hybrid PPy material that will provide advantageous properties for neural interfaces. Specifically, I describe the development of a polypyrrole:poly-(lactic-co-glycolic) acid blend for neural applications. In summary the three specific objectives covered in my thesis are: Specific Aim 1: Characterize and optimize the electrochemical synthesis of the conducting polymer, polypyrrole, for Schwann cell biocompatibility Specific Aim 2: Determine the effect of electrical stimulation on Schwann cell migration Specific Aim 3: Develop polypyrrole:poly-(lactic-co-glyolic) acid blends for neural engineering applications.