Electrospun nanofibers represent a class of versatile scaffolds for tissue engineering applications owing to their ability to mimic the nanoscale features of the native extracellular matrix (ECM). In addition, nanofibers produced by electrospinning can be readily collected as uniaxially aligned assemblies to recapitulate the architecture of the ECM in tissues with anisotropic characteristics, such as tendon-to-bone insertions, tendons, and nerves. This dissertation focuses on the design, fabrication, functionalization, and assessment of various types of scaffolds consisting of aligned nanofibers, which can be used to augment regeneration in tissues with anisotropic structures. Briefly, for tendon-to-bone insertion repair, I assessed the capability of aligned nanofibers with a gradient in mineral content to induce spatially graded osteogenesis of adipose-derived mesenchymal stem cells (ASCs). I also developed an alternative approach to the production of a gradient in the density of osteoblasts. The graded pattern of osteoblasts generated using both approaches could mimic their distribution in the native tendon-to-bone insertion. To further enhance the stiffness of the scaffolds, a new solution was developed to coat the scaffold with a thicker mineral layer. In a third project, a novel method of generating crimp in aligned nanofibers was developed. A solvent plasticizer was employed to release the residual stress retained in the nanofibers during electrospinning, which led to the generation of crimp. Finally, the outgrowth of neurites derived from embryoid bodies (EBs) was studied using aligned nanofibers as the substrates. Depending on the strength of adhesion between nanofibers and neurites, two patterns of outgrowth--parallel and perpendicular (to the alignment)--were observed. Maturation of neurons derived from dissociated EBs was also investigated, as characterized by their extracellular action potential and the ability to form neuromuscular junctions with co-cultured muscle cells.

Thesis (Ph. D. in Chemistry)--Vanderbilt University, Aug. 2006. / Title from title screen. Includes bibliographical references.

Thesis (Ph.D.)--Ohio University, November, 2007. / Title from PDF t.p. Includes bibliographical references.

Thesis (Ph.D.)--University of Nebraska-Lincoln, 2007. / Title from title screen (site viewed Sept. 18, 2008). PDF text: 215 p. : ill. (some col.) ; 14 Mb. UMI publication number: AAT 3305412. Includes bibliographical references. Also available in microfilm and microfiche formats.

No description available.

Schwann cell-seeded guidance channels have been exploited to bridge and guide axonal re-growth across gaps in lesioned nerves. Mis-orientation of Schwann cells in the channels can however distort axonal growth within the lesion. We therefore propose to orient the growth of Schwann cells on aligned nanofibers such that axonal growth can be guided along the designated direction towards the target. Chitosan was the choice scaffold material given its biocompatibility and the tunable susceptibility to biodegradation. To be suitable for electrospinning, chitosan was dissolved in trifluoroacetic acid/methylene chloride solution. By replacing the grounded plate collector of the conventional electrospinning setup with parallel collector plates placed 1.6 cm apart, the positively charged chitosan fibersbecame alternately attracted to the parallel plates and ended up uniaxially aligned as fiber suspension across the plates. Stability of the chitosan fibers in aqueous, physiological environment was achieved with the use of sodium carbonate to neutralize residual acidity in the chitosan fiber preparation. Schwann cells seeded onto these stabilized aligned chitosan nanofibers aligned uniaxially with the chitosan nanofibers. In addition, by seeding dissociated cells of dorsal root ganglia (DRG, E14/15 rats) onto the uniaxially aligned nanofibers, both neurons and Schwann cells were aligned with uniaxial arrangement of nanofibers, and the Schwann cells showed myelination ofthe axons. A model of the chitosan nerve conduit was constructed with a core nanofiberbundle, and seeding of Schwann cells. Thesein vitro results provide proof-of-principle for pursuing improvement in post-traumatic recovery from nerve injury with use of uniaxially aligned chitosan nanofibers in Schwann cell-seeded nerve guidance channels. / published_or_final_version / Biochemistry / Master / Master of Philosophy

Thesis (MSc)--University of Stellenbosch, 2007. / Bibliography. Also available via the Internet.

Thesis (M.S.) in Chemical Engineering--University of Maine, 2008. / Includes vita. Includes bibliographical references (leaves 92-98).

Thesis (Ph.D.)--University of Delaware, 2006. / Principal faculty advisor: John F. Rabolt, Dept. of Materials Science. Includes bibliographical references.

Thesis (M.S.M.S.E.)--University of Delaware, 2007. / Principal faculty advisors: D. Bruce Chase and John F. Rabolt, Dept. of Materials Science & Engineering. Includes bibliographical references.