Functional Electrospun Nanofibers for Biocatalysis and Tissue Engineering

CANBOLAT, MEHMET FATIH. Functional Electrospun Nanofibers for Biocatalysis and Tissue Engineering. (Under the direction of Dr. Behnam Pourdeyhimi and Dr. Saad A. Khan). Significant scientific and technological developments in today’s world require a broad knowledge base and utilization of an interdisciplinary approach. Integrating multiple disciplines has opened up new possibilities such as tissue engineering and biocatalysis, which stemmed from the collaboration of physical and life sciences. Nanotechnology is another topic of interest that uses an interdisciplinary approach to solve problems that are encountered in various fields. Electrospinning, electrostatic spinning of polymeric solutions or polymer melts, is a promising technology used for the production of nanofibers. Due to the unique characteristics of nanofibers, electrospinning has gained popularity in many fields such as tissue engineering, biocatalysis, filtration, energy, and sensing. The overall objective of this work is to produce electrospun nanofiber biocomposites containing immobilized live cells and to improve the functionality and performance of these structures. These novel fibers may be used for applications in tissue engineering and biocatalysis. We studied two polymer systems, poly(vinyl alcohol) (PVA) and poly-(caprolactone) (PCL), two cell lines (3T3-L1 and yeast cells), and four electrospinning techniques (cell electrospinning, cell layering, single needle electrospinning, and coaxial electrospinning). In the first part of this study, we investigated the feasibility of using cell electrospinning, cell layering, and coaxial electrospinning with 3T3-L1 mouse fibroblast cells for the production of nanofiber biocomposite structures. While cell electrospinning deemed too stressful of a technique for the cells to survive, cell layering served as a promising technique for producing nanofibrous structures containing active cells. Upon further investigation, we determined the reason behind cell death in the cell electrospinning process was dehydration and fiber stretching. In the second part of this study, we tried to immobilize live yeast cells into electrospun nanofiber structures using cell electrospinning, cell layering, and coaxial electrospinning techniques. Additionally, an assessment of electrospinning process parameters, cell viability, and cell functionality after electrospinning was carried out. Nanofiber structures containing viable cells were obtained from all three electrospinning methods. Functionality of the biocomposite structures was tested using the eGFP expression test which provided promising results in whole-cell biocatalyst immobilization. In the last part of this study, we examined the effects of the nanofiber composition, solvent type, and layering method of nanofibrous materials on the propagation of 3T3-L1 mouse fibroblasts over 3 days. Statistical analysis was performed with SAS software program using P-values less than 0.05 considered as statistically significant. The best scaffold structure was produced using a high concentration of three ECM materials (matrigel, fibronectin, and collagen, (MFC)) with a PCL – HFIP polymer system and double layering approach. Functional Electrospun Nanofibers for Biocatalysis and Tissue Engineering by Mehmet Fatih Canbolat A dissertation submitted to the Graduate Faculty of North Carolina State University in partial fulfillment of the requirements for the degree of Doctor of Philosophy Fiber and Polymer Science Raleigh, North Carolina 2011