Matching Items (5)
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- All Subjects: Regenerative Medicine
- Creators: Chemical Engineering Program
Description
This thesis aims to incorporate exosomes into an electrospun scaffold for tissue engineering applications. The motivation for this work is to develop an implant to regenerate tissue for patients with laryngeal defects. It was determined that it is feasible to incorporate exosomes into an electrospun scaffold. This addition of exosomes does alter the scaffold properties, by decreasing the average fiber diameter by roughly a factor of three and increasing the average modulus by roughly a factor of two. Cells were cultured on a scaffold with exosomes incorporated and were found to proliferate more than on a scaffold alone. This research lays the groundwork for further developing and optimizing an electrospun scaffold with exosomes incorporated to elicit a tissue regenerative response.
ContributorsKennedy, Maeve (Author) / Pizziconi, Vincent (Thesis director) / McPhail, Michael (Committee member) / School of International Letters and Cultures (Contributor) / Chemical Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2020-05
Description
Musculoskeletal heterogenous tissues are crucial for dissipating mechanical load during physical activity. Modern procedures to repair these tissues have proven inadequate to restore full functionality, thus there is a need for alternative reconstructive methods. Consequently, tissue engineered scaffolds can mimic the native structure of tissues and trigger a healing response. Heterogenous tissues like the tendon-bone junction consist of an interdigitated fiber alignment gradient from the tendon to the bone. It has been shown that electrospun fiber alignment gradients can be fabricated from the incorporation of magnetic fields. In this study, manipulating electrostatic and magnetic interactions from various electrospinning collector arrangements were investigated for creating an interdigitated fiber alignment gradient. The collector arrangement consisting of a magnet overlaid with razor cut aluminum foil proved to provide increased control over the interfacial shape. The rapid transition at the interfacial region was verified with brightfield microscopy revealing an interdigitated gradient from highly aligned fibers to unaligned fibers.
ContributorsBusselle, Lincoln Pierce (Author) / Holloway, Julianne (Thesis director) / Tindell, Raymond (Committee member) / Chemical Engineering Program (Contributor, Contributor) / Barrett, The Honors College (Contributor)
Created2020-05
Description
Protein crystallization is a technique for the formation of three-dimensional protein crystals, which is widely utilized by scientists, engineers, and researchers. Protein crystallography allows for protein structures and functions to be studied. As proteins play a central role in biological systems and life itself, a deeper understanding of their structure-function properties is crucial to elucidating fundamental behaviors, such as protein folding in addition to the role that they play in emerging fields, such as, tissue engineering with application to the emerging field of regenerative medicine. However, a significant limitation toward achieving further advancements in this field is that in order to determine detailed structure of proteins from protein crystals, high-quality and larger size protein crystals are needed. Because it is difficult to produce adequate size, high-quality crystals, it remains difficult to determine the structure of many proteins. However, a new method using a microgravity environment to crystallize proteins has proven effective through various studies conducted on the International Space Station (ISS). In the presence of microgravity, free convection is essentially absent in the bulk solution where crystallization occurs, thus allowing for purely random Brownian motion to exist which favors the nucleation and growth of high-quality protein crystals. Many studies from the ISS to date have demonstrated that growing protein crystals in a microgravity environment produces larger and higher-quality crystals. This method provides new opportunities for better structure identification and analysis of proteins. Although there remains many more limitations and challenges in the field, microgravity protein crystallization holds many opportunities for the future of biotechnology and scientific development. The objective of this thesis was to study the crystallization of hen egg white lysozyme (HEWL) and determine the effects of both unit and microgravity on growth/size and quality of HEWL. Through preliminary trials using a universal ground-based reduced-gravity system, the crystallization of HEWL in a simulated microgravity environment was successfully conducted and the results reported are promising. The utility of continuous, scalable ground-based, microgravity platforms for studies on a wide range of material systems and behavior, such as, protein crystallization, has significant implications regarding its impact on many industries, including drug development as well as regenerative medicine.
ContributorsTran, Amanda Marie (Author) / Pizziconi, Vincent (Thesis director) / Alford, Terry (Committee member) / Chemical Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2020-12
Description
Shear-thinning hydrogels can be combined with other components to enable multi-functionality, including short fibers or particles [1]. For the inclusion of fibers, electrospinning has gained momentum as a simple technique to create tissue engineered scaffolds that mimic the fibrous nature of the extracellular matrix [2]. Combining electrospun fibers with a shear-thinning hydrogel has the potential to provide cells with essential physical cues while retaining injectability [3]. Cells do not adhere well to hyaluronic acid alone, thus, peptides or fibers can be incorporated into the hydrogel mixture to improve cell adherence and facilitate better cell-material interactions [1,4]. In the future, hydrogel composite systems including fibers and/or peptides can be manufactured using shear-thinning hydrogels as an ideal multi-functional, injectable hydrogel for tissue repair applications. To establish the effect of these components on composite injectability, injection force experiments were conducted to quantify break and glide force. There was no statistically significant difference in break force of Ad-MeHA + CD-HA guest-host hydrogels of 5 wt%, 6 wt%, 6 wt% with peptides, and 7 wt% HA. A significant difference (p < 0.001) in glide force of Ad-MeHA + CD-HA guest-host hydrogels between 5wt% and 7wt% was observed. There was no statistically significant difference in break force or glide force of Ad-MeHA + CD-HA 7 wt% guest-host hydrogels of 0, 0.5, or 1 wt% fibers (40 µm, 15% SPIONs).
ContributorsKhandelwal, Juhi (Author) / Holloway, Julianne (Thesis director) / Stabenfeldt, Sarah (Committee member) / Barrett, The Honors College (Contributor) / Chemical Engineering Program (Contributor)
Created2025-05
Description
The gold standard of treatment for large bone defects remains autograft bone, which suffers from limited availability and donor-site morbidity. As an alternative, bone tissue engineering seeks to use a combination of cells, biomolecules, and biomaterials to regenerate functional bone tissue. Hydroxyapatite is a key component of bone tissue and is particularly important for its function. Here, we developed an approach to mineralize electrospun fibers to mimic native bone mineralization and serve as a scaffold for bone repair. Two types of electrospun fiber systems were investigated: polycaprolactone (PCL) and norbornene-functionalized cellulose acetate (nor-CA). PCL fiber surfaces were activated with sodium hydroxide and calcium phosphate. Next, the fibrous scaffolds were incubated in simulated body fluid (SBF) for seven days. Three types of SBF were chosen for incubation: conventional (C-SBF), revised (R-SBF), and 4x revised (4x R-SBF). Mineralization was assessed using energy-dispersive X-ray spectroscopy, Alizarin Red S staining, and scanning electron microscopy. Calcium phosphate and sodium chloride-based mineralization were observed for all SBF formulations for PCL. 4x R-SBF resulted in a calcium-to-phosphorus molar ratio most like native hydroxyapatite. R-SBF also had a calcium-to-phosphorus ratio similar to that of hydroxyapatite. R-SBF and 4x R-SBF resulted in lower values of sodium deposition on PCL when compared to C-SBF and had distinct regions of calcium-phosphate and sodium-chloride mineralization. Nor-CA was synthesized using a Boc2O esterification reaction between 5-norbornene-2-carboxylic acid and cellulose acetate, and analysis revealed the norbornene functionalization to be 60.02%. A fluorescent dye, 7-mercapto-4-methylcoumarin, was also successfully bound to the surface of nor-CA fibers using a UV-mediated thiol-ene reaction. The selectivity of the reaction between samples exposed to UV and kept in the dark requires improvement in future work.
ContributorsKupfer, Joshua (Author) / Holloway, Julianne (Thesis director) / Schwarz, Grace (Committee member) / Barrett, The Honors College (Contributor) / Chemical Engineering Program (Contributor)
Created2025-05