Matching Items (3)
Filtering by
- Creators: Chemical Engineering Program
Description
This thesis investigates an interpenetrating network of polyacrylamide and poly acrylic acid for use in a dynamic tactile display, which presents traditionally two-dimensional electronic screens as three-dimensional topographical models that can be experienced through touch. This kind of display would allow for greater access to traditionally visual information for the visually impaired. This hydrogel demonstrates Upper Critical Solution Temperature (UCST) near room temperature which facilitates a swelling transition, characterized by a sharp increase in swelling as this temperature is surpassed. Through the utilization of light responsive additives, light can trigger this shift, as the additives harness visible light, convert it into heat to raise the gel’s temperature, and increase the volume of the gel. Light-responsive additives explored include chlorophyllin, gold nanoparticles, and carbon black. Each of these additives required unique synthesis planning and strategies in order to optimize the performance of the gels. Synthesized gels were characterized using thermal swelling tests, light response tests and compression tests to determine the material strength. The best performing additive was chlorophyllin and allowed for a 20.8%±4.5% percent weight increase upon exposure to light for 10 minutes. In addition to investigating light-responsive additives, modifications were pursued to alter the overall UCST behavior, such as the addition of sodium chloride. By adding sodium chloride into the hydrogel, the gel was found to have a wider transition. Overall, light-responsive behavior was developed, and further work can be done in improving the response time and degree of swelling in order to make this material more viable for use in a dynamic tactile display.
ContributorsSitterle, Philip Kerry (Author) / Dai, Lenore (Thesis director) / Xu, Yifei (Committee member) / School of Music (Contributor) / Chemical Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2018-12
Description
Traumatic brain injury (TBI) is a significant public health concern in the U.S., where approximately 1.7 million Americans sustain a TBI annually, an estimated 52,000 of which lead to death. Almost half (43%) of all TBI patients report experiencing long-term cognitive and/or motor dysfunction. These long-term deficits are largely due to the expansive biochemical injury that underlies the mechanical injury traditionally associated with TBI. Despite this, there are currently no clinically available therapies that directly address these underlying pathologies. Preclinical studies have looked at stem cell transplantation as a means to mitigate the effects of the biochemical injury with moderate success; however, transplants suffer very low retention and engraftment rates (2-4%). Therefore, transplants need better tools to dynamically respond to the injury microenvironment.
One approach to develop new tools for stem cell transplants may be to look towards the endogenous repair response for inspiration. Specifically, activated cell types surrounding the injury secrete the chemokine stromal cell-derived factor-1α (SDF-1α), which has been shown to play a critical role in recruiting endogenous neural progenitor/stem cells (NPSCs) to the site of injury. Therefore, it was hypothesized that improving NPSC response to SDF-1α may be a viable mechanism for improving NPSC transplant retention and migration into the surrounding host tissue. To this end, work presented here has 1. identified critical extracellular signals that mediate the NPSC response to SDF-1α, 2. incorporated these findings into the development of a transplantation platform that increases NPSC responsiveness to SDF-1α and 3. observed increased NPSC responsiveness to local exogenous SDF-1α signaling following transplantation within our novel system. Future work will include studies investigating NSPC response to endogenous, injury-induced SDF-1α and the application of this work to understanding differences between stem cell sources and their implications in cell therapies.
One approach to develop new tools for stem cell transplants may be to look towards the endogenous repair response for inspiration. Specifically, activated cell types surrounding the injury secrete the chemokine stromal cell-derived factor-1α (SDF-1α), which has been shown to play a critical role in recruiting endogenous neural progenitor/stem cells (NPSCs) to the site of injury. Therefore, it was hypothesized that improving NPSC response to SDF-1α may be a viable mechanism for improving NPSC transplant retention and migration into the surrounding host tissue. To this end, work presented here has 1. identified critical extracellular signals that mediate the NPSC response to SDF-1α, 2. incorporated these findings into the development of a transplantation platform that increases NPSC responsiveness to SDF-1α and 3. observed increased NPSC responsiveness to local exogenous SDF-1α signaling following transplantation within our novel system. Future work will include studies investigating NSPC response to endogenous, injury-induced SDF-1α and the application of this work to understanding differences between stem cell sources and their implications in cell therapies.
ContributorsAddington, Caroline (Author) / Stabenfeldt, Sarah E (Thesis advisor) / Kleim, Jeffrey A (Committee member) / Caplan, Michael R (Committee member) / Lifshitz, Jonathan (Committee member) / Massia, Stephen P (Committee member) / Arizona State University (Publisher)
Created2015
Description
Hydrocephalus is a chronic neurological condition affecting an estimated 1 in every 500 infants born. The most common treatment method involves surgical implantation of a shunt system; however these systems have a high failure rate resulting in repeat invasive surgeries. A promising approach being researched to treat hydrocephalus is a miniaturized valve composed of silicon and a hydrogel material. The current chemical cross-linker used in the hydrogel, EGDMA, however is susceptible to hydrolytic cleavage due to the ester groups.
This thesis proposed a novel hydrogel composed of a HEMA backbone and methacrylated Jeffamines as the chemical cross-linker as a possible replacement for the HEMA and EGDMA hydrogel used currently in the hydrocephalus valve. Jeffamine EDR-148 was methacrylated through reaction with methacryloyl chloride and characterized using 1H NMR spectroscopy. Subsequently, hydrogels were synthesized, using both EGDMA and EDR-MA, and the properties were compared through swelling and rotational rheology. Finally, degradation tests were performed to compare the hydrolytic stability of the two cross-linkers.
Results of this work demonstrated that Jeffamine EDR-148 was able to be successfully methacrylated and used to synthesize a hydrogel. The new hydrogel was shown to have comparable mechanical behavior and robustness to the EGDMA hydrogel, with slightly increased swelling capabilities. Degradation tests did not confirm the theory that the EDR-MA gels would exhibit greater hydrolytic stability however. Future work includes perfecting the purification of the EDR-MA, conducting a longer-term degradation study at physiologically relevant conditions, and demonstrating the tunability of the Jeffamine hydrogels.
This thesis proposed a novel hydrogel composed of a HEMA backbone and methacrylated Jeffamines as the chemical cross-linker as a possible replacement for the HEMA and EGDMA hydrogel used currently in the hydrocephalus valve. Jeffamine EDR-148 was methacrylated through reaction with methacryloyl chloride and characterized using 1H NMR spectroscopy. Subsequently, hydrogels were synthesized, using both EGDMA and EDR-MA, and the properties were compared through swelling and rotational rheology. Finally, degradation tests were performed to compare the hydrolytic stability of the two cross-linkers.
Results of this work demonstrated that Jeffamine EDR-148 was able to be successfully methacrylated and used to synthesize a hydrogel. The new hydrogel was shown to have comparable mechanical behavior and robustness to the EGDMA hydrogel, with slightly increased swelling capabilities. Degradation tests did not confirm the theory that the EDR-MA gels would exhibit greater hydrolytic stability however. Future work includes perfecting the purification of the EDR-MA, conducting a longer-term degradation study at physiologically relevant conditions, and demonstrating the tunability of the Jeffamine hydrogels.
ContributorsTrimble, Kari Leigh (Author) / Green, Matthew (Thesis director) / Chae, Junseok (Committee member) / Chemical Engineering Program (Contributor, Contributor) / Barrett, The Honors College (Contributor)
Created2019-05