ETDs

This collection includes most of the ASU Theses and Dissertations from 2011 to present. ASU Theses and Dissertations are available in downloadable PDF format; however, a small percentage of items are under embargo. Information about the dissertations/theses includes degree information, committee members, an abstract, supporting data or media.

In addition to the electronic theses found in the ASU Digital Repository, ASU Theses and Dissertations can be found in the ASU Library Catalog.

Dissertations and Theses granted by Arizona State University are archived and made available through a joint effort of the ASU Graduate College and the ASU Libraries. For more information or questions about this collection contact or visit the Digital Repository ETD Library Guide or contact the ASU Graduate College at gradformat@asu.edu.

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Single cell force spectroscopy for quantification of cellular adhesion on surfaces

Description
Cell adhesion is an important aspect of many biological processes. The atomic force microscope (AFM) has made it possible to quantify the forces involved in cellular adhesion using a technique called single cell force spectroscopy (SCFS). AFM based SCFS offers versatile control over experimental conditions for probing directly the interaction…

Cell adhesion is an important aspect of many biological processes. The atomic force microscope (AFM) has made it possible to quantify the forces involved in cellular adhesion using a technique called single cell force spectroscopy (SCFS). AFM based SCFS offers versatile control over experimental conditions for probing directly the interaction between specific cell types and specific proteins, surfaces, or other cells. Transmembrane integrins are the primary proteins involved in cellular adhesion to the extra cellular matix (ECM). One of the chief integrins involved in the adhesion of leukocyte cells is αMβ2 (Mac-1). The experiments in this dissertation quantify the adhesion of Mac-1 expressing human embryonic kidney (HEK Mac-1), platelets, and neutrophils cells on substrates with different concentrations of fibrinogen and on fibrin gels and multi-layered fibrinogen coated fibrin gels. It was shown that multi-layered fibrinogen reduces the adhesion force of these cells considerably. A novel method was developed as part of this research combining total internal reflection microscopy (TIRFM) with SCFS allowing for optical microscopy of HEK Mac-1 cells interacting with bovine serum albumin (BSA) coated glass after interacting with multi-layered fibrinogen. HEK Mac-1 cells are able to remove fibrinogen molecules from the multi-layered fibrinogen matrix. An analysis methodology for quantifying the kinetic parameters of integrin-ligand interactions from SCFS experiments is proposed, and the kinetic parameters of the Mac-1 fibrinogen bond are quantified. Additional SCFS experiments quantify the adhesion of macrophages and HEK Mac-1 cells on functionalized glass surfaces and normal glass surfaces. Both cell types show highest adhesion on a novel functionalized glass surface that was prepared to induce macrophage fusion. These experiments demonstrate the versatility of AFM based SCFS, and how it can be applied to address many questions in cellular biology offering quantitative insights.
ContributorsChristenson, Wayne B (Author) / Ros, Robert (Thesis advisor) / Beckstein, Oliver (Committee member) / Lindsay, Stuart (Committee member) / Ugarova, Tatiana (Committee member) / Arizona State University (Publisher)
Created2016
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Electric Field Modulation of Cells: From Signaling Pathway to Physiological Behaviors

Description
The response of living cells to electric field (EF) has been observed for more than a hundred years, but the mechanism of how cells interact with EF is not entirely ascertained. Although many efforts have been devoted to the application of EF stimulation in tissue engineering and regeneration, the fundamental…

The response of living cells to electric field (EF) has been observed for more than a hundred years, but the mechanism of how cells interact with EF is not entirely ascertained. Although many efforts have been devoted to the application of EF stimulation in tissue engineering and regeneration, the fundamental scientific principle of such practice remains unveiled and keeps drawing attention during the pursuit of consistent outcomes. In this regard, my research focuses on the underlying mechanism by which EF stimulation evokes cellular responses and the EF modulation of cell signaling pathways to physiological behaviors. The first part of my research focuses on developing the platform for controlled EF stimulation and real-time imaging/analysis. High-k dielectric passivated microelectrodes are fabricated to send capacitively coupled alternating current electric field (AC EF) stimulation to cells. I have developed two generations of EF stimulation devices with environmental control chambers: the first one is used to study cell signaling pathway dynamics; the second one is upgraded with long-term culture capability to study cell physiological behaviors. The second part of my research focuses on the quantification and mechanistic study of AC EF perturbation of the extracellular signal-related kinase (ERK) signaling pathway. I demonstrate that AC EF stimulation can induce both inhibition and activation of the ERK pathway, with different AC EF amplitude thresholds and time and magnitude scales. The mechanistic study shows that the ERK activation is initiated by AC EF-induced epidermal growth factor receptor (EGFR) phosphorylation, and the ERK inhibition is related to AC EF-induced change of Ras activities. In addition, these ERK responses show high sensitivity to AC EF waveform and timing, indicating electrostatic coupling mechanism and providing new parameter spaces for further investigation on the modulation of the ERK signaling pathway via AC EF stimulation. The last part of my research steers to cell physiological behaviors under prolonged AC EF stimulation. I report that AC EF stimulation can clearly inhibit cell proliferation and migration, and the inhibition in cell proliferation is sensitive to AC EF amplitude, stimulation pattern, and pulse rising time. These findings can benefit the AC EF application in medical treatment.
ContributorsHu, Minxi (Author) / Qing, Quan (Thesis advisor) / Lindsay, Stuart (Committee member) / Guo, Jia (Committee member) / Arizona State University (Publisher)
Created2023
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Start to Signal: A Novel Approach to Isothermal Assay Design for Point-of-care Detection of Emerging Pathogens

Description
Emerging pathogens present several challenges to medical diagnostics. Primarily, the exponential spread of a novel pathogen through naïve populations require a rapid and overwhelming diagnostic response at the site of outbreak. While point-of-care (PoC) platforms have been developed for detection of antigens, serologic responses, and pathogenic genomes, only nucleic acid…

Emerging pathogens present several challenges to medical diagnostics. Primarily, the exponential spread of a novel pathogen through naïve populations require a rapid and overwhelming diagnostic response at the site of outbreak. While point-of-care (PoC) platforms have been developed for detection of antigens, serologic responses, and pathogenic genomes, only nucleic acid diagnostics currently have the potential to be developed and manufactured within weeks of an outbreak owing to the speed of next-generation sequencing and custom DNA synthesis. Among nucleic acid diagnostics, isothermal amplification strategies are uniquely suited for PoC implementation due to their simple instrumentation and lack of thermocycling requirement. Unfortunately, isothermal strategies are currently prone to spurious nonspecific amplification, hindering their specificity and necessitating extensive empirical design pipelines that are both time and resource intensive. In this work, isothermal amplification strategies are extensively compared for their feasibility of implementation in outbreak response scenarios. One such technology, Loop-mediated Amplification (LAMP), is identified as having high-potential for rapid development and PoC deployment. Various approaches to abrogating nonspecific amplification are described including a novel in silico design tool based on coarse-grained simulation of interactions between thermophilic DNA polymerase and DNA strands in isothermal reaction conditions. Nonspecific amplification is shown to be due to stabilization of primer secondary structures by high concentrations of Bst DNA polymerase and a mechanism of micro-complement-mediated cross-priming is demonstrated as causal via nanopore sequencing of nonspecific reaction products. The resulting computational model predicts primer set background in 64% of 67 test assays and its usefulness is illustrated further by determining problematic primers in a West Nile Virus-specific LAMP primer set and optimizing primer 3’ nucleotides to eliminate micro-complements within the reaction, resulting in inhibition of background accumulation. Finally, the emergence of Orthopox monkeypox (MPXV) as a recurring threat is discussed and SimCycle is utilized to develop a novel technique for clade-specific discrimination of MPXV based on bridging viral genomic rearrangements (Bridging LAMP). Bridging LAMP is implemented in a 4-plex microfluidic format and demonstrates 100% sensitivity in detection of 100 copies of viral lysates and 45 crude MPXV-positive patient samples collected during the 2022 Clade IIb outbreak.
ContributorsKnappenberger, Mark Daniel (Author) / Anderson, Karen S (Thesis advisor) / LaBaer, Joshua (Committee member) / Roberson, Robert (Committee member) / Lindsay, Stuart (Committee member) / Arizona State University (Publisher)
Created2023