The need for tissue and organ replacements cannot be satisfied by autograft and allografts alone. The purpose of this study was to investigate the feasibility of electrospinning a blend of polydioxanone and fibrinogen to produce an engineered tissue scaffold. Fiber diameter and pore size of blends were characterized, as well as mechanical strength. Cell proliferation assays for 1 and 7 day cultures were preformed, and a histological evaluation was performed to determine how favorable the various blends were to cell infiltration and proliferation. Some ratios of blends were identified that contained both acceptable mechanical properties and properties that facilitated cell infiltration. These findings pave the way for future refinement and use of these scaffolds for a variety of tissue engineered targets.

For fuel cells to become commercially viable in a wider range of applications, the amount of catalyst must be reduced. One crucial area of the fuel cell assembly is the anode and cathode; these layers allow fuel and exhaust gases to diffuse, provide conduction paths for both protons and electrons, and house sites for electrocataytic reactions. Despite their multi-functionality and importance, these layers have received little attention in the way of engineering design. While Nafion and catalyst loading has been studied, the electrode layer is still considered a two-dimensional structure. By understanding the current electrode limitations, available materials, and interactions at the sites reaction sites, an intelligent, deliberate design of the anode and cathode layer can be undertaken. A three-dimensional, fibrous mat of continuous, networked proton-conducting fibers can decrease mass diffusion limitations while maintaining proton conductivity. Nafion can be formed into these types of fibers via the fabrication technique of electrospinning. By forcing a solution of Nafion, solvent, and carrier polymer through a small nozzle under high electric voltage, the polymer can be extruded into fibers with nanometer-scale diameters. The ability to control the fiber morphology lies with solution, environmental and equipment properties. In order to successfully fabricate Nafion nanofibers, we looked to both existing methodologies as well as mathematical models to try to predict behavior and fabricate our own nanofibers. Once fabricated, these mats are assembled in a membrane-electrode assembly and tested with both methanol and hydrogen as fuel, with performance compared against known data for conventional MEAs. We have been able to successfully electrospin Nafion® nanofibers continuously, creating fiber mats with fiber diameters near 400nm as verified by SEM. These mats were tested in a direct methanol fuel cell (DMFC) application as cathodes, and showed improved performance with a dilute methanol feed compared to conventional MEAs with equivalent Nafion and catalyst loading. An MEA fabricated with twin electrospun electrodes was compared against an equivalent conventional MEA, showing the same performance enhancement using a dilute methanol fuel.

The objective of this work is to electrospin poly(acrylonitrile) (PAN) based nanofibers with controlled diameter and to stabilize and carbonize them for developing meso-porous carbon for application as electrochemical capacitor electrodes. A sacrificial polymer, poly(styrene-co-acrylonitrile) (SAN) has been used to control porosity. Carbon nanotubes (CNT) have been used to increase electrode conductivity and hence power density. The study has been divided into two parts. In part I, electrospinning behavior of PAN and PAN/CNT has been studied. The diameter of electrospun PAN fibers was monitored as a function of polymer molecular weight, solution concentration, solution flow rate, distance between the spinneret and the target, and the applied voltage. Bead free PAN fibers of 60 nm diameter have been electrospun. Various electrospun fibers have been characterized by wide angle X-ray diffraction and by Raman spectroscopy. Electrospinning process has been observed by high speed photography. In part II, the electrospun PAN, PAN/SAN, and PAN/SAN/CNT fiber mats were stabilized, carbonized, and processed into electrochemical capacitor electrodes. The performance of the electrochemical capacitors was tested by the constant current charge/discharge and cyclic voltammetry in 6 molar potassium hydroxide aqueous solution. The surface area and pore size distribution of the electrodes were measured using N2 adsorption and desorption. The effect of surface area and pore size distribution on the capacitance performance has been studied. The capacitance performance of various carbonized electrospun fibers mats have been compared to those of the PAN/SAN/CNT film, carbon nanotube bucky paper, and activated carbon pellet. The capacitance of PAN/SAN/CNT fiber mat over 200 F/g (at a current density of 1 A/g) and the power density approaching 1 kW/kg have been observed. Addition of 1 wt% carbon nanotubes in PAN/SAN, improves the power density by a factor of four. For comparison, the capacitance of single wall carbon nanotube bucky paper at a current density of 1 A/g is about 50 F/g.

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HNSCC accounts for 7 percent of all new cancer occurrences. Despite currently available treatments, there continues to be a high mortality and recurrence rate in HNSCC. Well over 50 percent of all cancer patients receive chemotherapy as a standard treatment. However, only 5 percent of these cases have been shown to help with treatment of the disease. Formerly, two options were available for drug testing: in vivo animal models, and in vitro two-dimensional models. While in vivo models remain the most representative, their use is burdened by high costs, time constraints, and ethical concerns. 2D models are simple to use and cost effective, although they have been shown to produce inaccurate data regarding chemotherapeutic drug resistance due to their 2D arrangement and altered gene expression. Researchers for the past decade have been working to create 3D models that more accurately represent in vivo systems in order to evaluate chemotherapeutic efficacy and improve clinical outcomes. In line with this agenda, novel 3D head and neck cancer models were created out of electrospun synthetic polymers seeded with either HN6 or HN12 cancer cells. The models were then treated with chemotherapeutic drugs (either paclitaxel or cisplatin), and, after 72 hours, subjected to a live-dead assay in order to determine the cytotoxic effects of the drugs. 2D cultures of HN6 and HN12 were also and subject to a WST-1 assay after 72 hours. The results of the treated-scaffold assays were then compared to the results of the 2D culture assays, and, as predicted, the cancer cells in a 3D culture system proved to be more resistant to chemotherapeutic drugs. The underlying assumption for this study being that a 3D culture system based on precisely defined structural parameters would provide a practical environment to screen therapeutics for anti-cancer efficacy. To prove this, 3D scaffolds of three different fiber sizes were developed by electrospinning different concentrations of Poly(L-lactic acid) (“PLLA”) (55mg/ml, 115mg/ml, and 180mg/ml) onto a mandrel that was perforated to allow for increased porosity. The resultant small, medium, and large scaffolds were then subjected to concentrated hydrochloric acid (HCl) pretreatment in order to make them less hydrophobic. Different fiber diameters represented different ECM environments for both HN6 and HN12. It was proven that both cell types thrived best in small fibers (55mg/ml-115mg/ml) than in large fibers. It was also reaffirmed through live-dead anlaysis of cells seeded on 3D scaffolds and treated with IC90 values of cisplatin that the head and neck cancer cells were more resistant which is more representative to the 3D environment of cancer cells in vivo.

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This work seeks to fabricate, optimize, and characterize nanofibers of cactus Opuntia ficus-indica mucilage and Poly (vinyl alcohol) (PVA) by electrospinning. Mucilage is a neutral mixture of sugars produced by cactus and PVA is a non-toxic, water-soluble, synthetic polymer, which is widely used as a co-spinning agent for polymers. Mucilage was extracted from the cactus pad and prepared for electrospinning by mixing with acetic acid. Two types of PVA were used differentiating in high and low molecular weights. Concentrations of PVA were varied to find an adequate threshold for fiber formation. Changing the ratio of PVA to cactus mucilage produced fibers of different diameter and quality. The optimizations of the parameters used in the electrospinning setup were also a factor in creating quality fibers without deformity. An acceptable PVA to mucilage ratio mixture was reached for the use of the electrospinning process and consistent nanofibers were accomplished with the use of both the low and high molecular weight PVA. The fibers were observed using a Scanning Electron Microscope, Atomic Force Microscopy, and Differential Scanning Calorimetry. In this project we were able to obtain nanofiber meshes made with environmentally friendly materials with fiber diameters raging from 50nm to 7um sized. The produced nanofibers were made in the hope that it can be utilized in the future as an inexpensive, biocompatible, and biodegradable water filtration system.