Matching Items (311)
Description
p-Coumaric acid is used in the food, pharmaceutical, and cosmetic industries due to its versatile properties. While prevalent in nature, harvesting the compound from natural sources is inefficient, requiring large quantities of producing crops and numerous extraction and purification steps. Thus, the large-scale production of the compound is both difficult and costly. This research aims to produce p-coumarate directly from renewable and sustainable glucose using a co-culture of Yeast and E. Coli. Methods used in this study include: designing optimal media for mixed-species microbial growth, genetically engineering both strains to build the production pathway with maximum yield, and analyzing the presence of p-Coumarate and its pathway intermediates using High Performance Liquid Chromatography (HPLC). To date, the results of this project include successful integration of C4H activity into the yeast strain BY4741 ∆FDC1, yielding a strain that completely consumed trans-cinnamate (initial concentration of 50 mg/L) and produced ~56 mg/L p-coumarate, a resting cell assay of the co-culture that produced 0.23 mM p-coumarate from an initial L-Phenylalanine concentration of 1.14 mM, and toxicity tests that confirmed the toxicity of trans-cinnamate to yeast for concentrations above ~50 mg/L. The hope for this project is to create a feasible method for producing p-Coumarate sustainably.
ContributorsJohnson, Kaleigh Lynnae (Author) / Nielsen, David (Thesis director) / Thompson, Brian (Committee member) / Chemical Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2016-12
Description
Research concerning increased sensitivity and accurate glucose sensors have been on the forefront of diabetes mellitus. In this study, Electroactive Poly-Amidoamine Polymer (EPOP) was studied to determine if it can be used as a biocompatible electrode, with known redox mediators to determine if it can transfer its own electrons or amplify signal, and if signal is amplified when using an Ag/AgCl working electrode. From the results, it was determined that EPOP is neither a redox mediator, since it cannot transfer its own electrons, nor an electron mediator, since it does not amplify measured current at a specific voltage. Rather, it behaves as an electron sink capacitor with inconsistent behavior when Ag/AgCl is used as the working electrode with the redox mediator alone or with the redox mediator using in combination with glucose oxidase (GOx) and glucose. This was validated using AC-Impedance which gave a -3.3999 slope for isolated 0.05 g/mL EPOP in solution and R2 value of 0.992 displaying it had more capacitor-like behavior compared to resistor-like behavior. For this reason, EPOP was infused into a carbon screen-printed electrode by adding it dissolved and undissolved at two levels into carbon ink. The effectiveness of this electrode was tested using a potentiostatic CV. For the 0.1 g/mL EPOP dissolved in carbon ink, the reduction voltage peak (0.18 V) was found to be slightly higher than a GDE (0.14 V); however, the measured current was found to be 1.57 times the amplitude of a GDE. When 0.05 g/mL EPOP in PBS dissolved in graphite ink was used to detect glucose as the working electrode, there was increased signal amplification, and therefore, increased sensitivity to glucose when using EPOP infused electrodes. This offers promising results for disposable glucose sensors.
ContributorsKapadia, Meera Vipul (Author) / LaBelle, Jeffrey (Thesis director) / Islam, Rafiqul (Committee member) / Honikel, Mackenzie (Committee member) / Chemical Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2017-05
Description
The C6T single-chain variable fragment (scFv) is an antibody fragment designed as a potential Alzheimer’s therapeutic protein. However, this protein has been shown to be unstable and difficult to express in E. coli. In this project, the C6T scFv is converted into an antigen-binding fragment (Fab), a larger and more stable antibody fragment. A C6T Fab sequence was derived from the scFv sequence, and a plasmid containing genes to express the Fab was constructed. Due to the disulfide-bonded structure of Fabs, the protein needs to be exported to the periplasm to properly fold. Therefore, the stII post-translational periplasmic secretion signal sequence was built into the expression vector, preceding both the heavy and light chain of the C6T Fab. The plasmid was transformed and expressed in BW25113 E. coli cells. A polyhistidine-tag was added to the Fab and it was purified on a nickel bead column. Protein characterization demonstrated that the correct Fab was produced.
Efforts were then made to optimize the expression of the C6T Fab in E. coli. Both the periplasmic secretion pathway and the effect of trigger factor were tested. Four expression systems were tested, consisting of one of two signal sequences (either DsbA directing through the SRP-dependent co-translational pathway or stII directing through the sec-dependent post-translational pathway) and one of two expression strains (BW25113 (tig+) containing trigger factor and KTD101 (Δtig) lacking trigger factor). Plasmids were constructed allowing the C6T Fab to be expressed and secreted using both pathways, and transformed into both strains. It was predicted that the protein expression could be optimized by employing the co-translational pathway in cells lacking trigger factor (i.e. the Δtig-DsbA expression system). However, this system severely decreased cell growth post-induction. It was found that both the lack of trigger factor and the employment of the co-translational pathway both significantly decrease cell growth post-induction. It is theorized that the increase in protein expression and secretion rate stresses the cell to a point where it is unable to maintain normal cell function and growth.
Efforts were then made to optimize the expression of the C6T Fab in E. coli. Both the periplasmic secretion pathway and the effect of trigger factor were tested. Four expression systems were tested, consisting of one of two signal sequences (either DsbA directing through the SRP-dependent co-translational pathway or stII directing through the sec-dependent post-translational pathway) and one of two expression strains (BW25113 (tig+) containing trigger factor and KTD101 (Δtig) lacking trigger factor). Plasmids were constructed allowing the C6T Fab to be expressed and secreted using both pathways, and transformed into both strains. It was predicted that the protein expression could be optimized by employing the co-translational pathway in cells lacking trigger factor (i.e. the Δtig-DsbA expression system). However, this system severely decreased cell growth post-induction. It was found that both the lack of trigger factor and the employment of the co-translational pathway both significantly decrease cell growth post-induction. It is theorized that the increase in protein expression and secretion rate stresses the cell to a point where it is unable to maintain normal cell function and growth.
ContributorsAdams, Jeremy David (Author) / Nannenga, Brent (Thesis director) / Chemical Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2016-12
Description
The objective of this research is to create biodegradable mats with tunable characteristics such as fiber diameter and surface area. The drug delivery mats enable spatially controlled delivery of disease-specific therapeutics. Using a large electric potential to draw fibers from a solution flowing at a specific rate, the polymer fibers reach a grounded target several inches away. The biodegradable polymer used in this study was poly(lactic acid-co-glycolic acid) (PLGA). PLGA solutions ranging from 0.5 to 27 wt.% were prepared by dissolving the block copolymer in a solvent mixture containing tetrahydrofuran (THF) and dimethylformamide (DMF) at a 3:1 weight ratio. They were then electrospun at needle-to-target distances of 7, 14, and 18 cm and rates ranging from 0.8 to 4 mL/h. The range of voltage used was between 8 – 15 kV, which was based on the observation of the formation of a Taylor cone, largely affected by on the environment and weather (e.g., temperature and humidity in the lab). A 27 wt.% PLGA solution, electrospun at 1 mL/h at a voltage of 11.25 kV and needle-to-target distance of 14 cm produced uniform fibers with an average fiber diameter of 0.985 m. All other parameters outside the range given created beaded fibers. In addition, solution rheology was performed on some of the PLGA solution to measure viscosity, which is directly correlated to the fiber diameter of the electrospun mats. Observing the impact of solvent on fiber spinning and fiber diameter brings about many positive results in developing fully characterized and well-understood fibrous mats for drug delivery. The nanoscale fibers will be used as drug delivery mats and, therefore, the biodegradation kinetics of the polymers will be studied. Next, parameters of the polymers as well as the polymeric mats will be correlated to the degradation-mediated release of small molecule therapeutics (e.g., peptides, drugs, etc.) such that time-resolved dosing profiles can be created.
ContributorsLent, Madeline (Author) / Green, Matthew (Thesis director) / Holloway, Julianne (Committee member) / Chemical Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2016-12
Description
Enhancing the expression levels of Fabs (antigen-binding antibody fragments) in Escherichia coli is a difficult field that has a variety of potential exciting implications. The field has grown substantially in the past twenty years. The main area of difficulty is facilitating the entry of the antibody fragments into the periplasm of E. Coli, where the antibody fragments can be successfully expressed. Entry into the periplasm is difficult for antibody fragments due to their inability to fold in any other section besides the periplasm. Therefore it is necessary for the antibody to enter the periplasm in an unfolded state. Background research was done into inspecting the three primary methods of periplasmic entry: the Sec-dependent pathway, the SRP-dependent pathway (signal recognition particle) and the TAT-dependent pathway (twin arginine translocase). The Sec-dependent and SRP-dependent pathways were deemed more viable for expressing antibodies due to their ability to transfer an unfolded protein into the periplasm, which the TAT-dependent pathway cannot do. Academic research showed that the Sec-dependent and SRP-dependent pathways were equally viable methods, with more research being done into the Sec-dependent pathway, particularly of the OmpA signal sequence. Physical experiments were done using typical cloning procedures with slight modifications to the ligation step (Gibson Assembly was performed instead of normal ligation). These physical experiments showed that the Sec-dependent and SRP-dependent pathways were equally viable methods of periplasmic entry. The A4 and C6 antibodies were successfully expressed using these pathways. These antibodies were expressed on an SDS gel using 10% SDS. It was hypothesized that with further experimental modifications, using different signal sequences, Fabs can be expressed at higher and more consistent level.
ContributorsParker, Matthew David (Author) / Nannenga, Brent (Thesis director) / Nielsen, David (Committee member) / Chemical Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2016-12
Description
Rotary equipment has been used widely in the processing of particulates for the last century, but low thermal efficiency and poor effluent uniformity continue to plague its performance. Consequently, these technologies contribute largely to modern energy waste, environmental pollution, and price inflation of products dependent on particulates in their manufacture. Large industries like pharmaceuticals and oil are impacted, yet minimal research has been conducted into optimizing the equipment because of costs associated with process shut-downs necessary to enable study. Recent works bypassed this constraint with simulations and scaled-down replicates to observe impact of common design parameters, fill level and rotation speed, on heating. This thesis supplanted these studies by investigating particle diameter as a control parameter to optimize heating. The thesis investigated methodologies to study a stainless-steel rotary drum model facilitating the conductive heating of a silica bed by external heat guns. Diameter was varied 2-4 mm at controlled fill levels and rotation speeds, and radial temperature profiles were measured with thermocouples. Heating performance was evaluated for efficiency and uniformity; the former by analyzing thermal time constants and average temperature progression across 70 minutes of operation, and the latter with corresponding radial temperature variances. It was theorized that the direct influence of size on transport properties would implicate an inverse correlation between diameter and performance, but results demonstrated no significance. The apparatus and methodology were still under development, so results were preliminary. From results, the study proposed setup modifications to refine results and future directions to guide follow-up research.
ContributorsDeBruin, Dylan (Author) / Emady, Heather (Thesis director) / Adepu, Manogna (Committee member) / Chemical Engineering Program (Contributor, Contributor) / Barrett, The Honors College (Contributor)
Created2017-05
Description
Genetic manipulation of human cell lines has widespread applications in biomedical research ranging from disease modeling to therapeutic development. Human cells are generally difficult to genetically engineer, but exogenous nucleic acids can be expressed by viral, chemical, or nonchemical means. Chemical transfections are simpler in practice than both viral and nonchemical delivery of genetic material, but often suffer from cytotoxicity and low efficiency. Novel aminoglycoside antibiotic-derived lipopolymers have been synthesized to mediate transgene delivery to human cells. These polymers are comprised of either paromomycin or apramycin crosslinked with glycerol diglycidylether and derivatized with stearoyl chloride in varying molar ratios. In this work, three previously identified target lipopolymers were screened against a library of human embryonic and induced pluripotent stem cell lines. Cells were transfected with a plasmid encoding green fluorescent protein (GFP) and expression was quantified with flow cytometry 48 hours after transfection. Transfection efficiency was evaluated between three distinct lipopolymers and four lipopolymer:DNA mass ratios. GFP expression was compared to that of cells transfected with commercially available chemical gene delivery reagent controls\u2014JetPEI, Lipofectamine, and Fugene\u2014at their recommended reagent:DNA ratios. Improved transgene expression in stem cell lines allows for improved research methods. Human stem cell-derived neurons that have been genetically manipulated to express phenotypic characteristics of aging can be utilized to model neurodegenerative diseases, elucidating information about these diseases that would be inaccessible in unmanipulated tissue.
ContributorsMehta, Frea (Author) / Brafman, David (Thesis director) / Rege, Kaushal (Committee member) / Chemical Engineering Program (Contributor) / School of Life Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2017-05
Description
The objective of this research study is to assess the effectiveness of a poster-based messaging campaign and engineering-based activities for middle school and high school students to encourage students to explore and to pursue chemical engineering. Additionally, presentations are incorporated into both methods to provide context and improve understanding of the presented poster material or activity. Pre-assessments and post-assessments are the quantitative method of measuring effectiveness. For the poster campaign, ASU juniors and seniors participated in the poster campaign by producing socially relevant messages about their research or aspirations to address relevant chemical engineering problems. For the engineering-based activity, high school students participated in an Ira A. Fulton Schools of Engineering program "Young Engineers Shape the World" in which the students participated in six-hour event learning about four engineering disciplines, and the chemical engineering presentation and activity was conducted in one of the sessions. Pre-assessments were given at the beginning of the event, and the post-assessments were provided towards the end of the event. This honors thesis project will analyze the collected data.
ContributorsBueno, Daniel Tolentino (Author) / Ganesh, Tirupalavanam (Thesis director) / Parker, Hope (Committee member) / Chemical Engineering Program (Contributor) / School of Historical, Philosophical and Religious Studies (Contributor) / W. P. Carey School of Business (Contributor) / Barrett, The Honors College (Contributor)
Created2017-05
Description
Polymer modified tuning fork-based sensors were fabricated to assure reproducibility. The effect of system valve switching on the modified tuning fork-based sensors was studied at the different temperature. The response to Xylene gas sample on stabilized modified tuning fork-based sensors with temperature was defined while learning about the key analytical performance for chemical sensors to be used in the real-world application.
ContributorsRohit, Riddhi S (Author) / Forzani, Erica (Thesis director) / Tsow, Francis (Committee member) / Dean, W.P. Carey School of Business (Contributor) / Chemical Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2017-05
Description
The overall goal of this project is to use metallic nanoparticles to develop a thin, ductile amorphous film at room temperature. Currently bulk metallic glasses are mainly formed via quenching, which requires very high cooling rates to achieve an amorphous molecular structure. These formations often fail in a brittle manner. The advantages of using a bottom-up approach with amorphous nanoparticles at ambient conditions is that the ductility of the metal can be improved, and the process will be less energy intensive. The nanoparticles used are iron precursors with ATMP and DTPMP ligand stabilizers and dispersed in methanol. Three forms of experimentation were applied over the course of this project. The first was a simple, preliminary data collection approach where the particles were dispersed onto a glass slide and left to dry under various conditions. The second method was hypersonic particle deposition, which accelerated the particles to high speeds and bombarded onto a glass or silicon substrate. The third method used Langmuir-Blodgett concepts and equipment to make a film. Qualitative analyses were used to determine the efficacy of each approach, including SEM imaging. In the end, none of the approaches proved successful. The first approach showed inconsistencies in the film formation and aggregation of the particles. The results from the hypersonic particle deposition technique showed that not enough particles were deposited to make a consistent film, and many of the particles that were able to be deposited were aggregated. The Langmuir-Blodgett method showed potential, but aggregation of the particles and uneven film formation were challenges here as well. Although there are ways the three discussed experimental approaches could be optimized, the next best step is to try completely new approaches, such as convective assembly and 3D printing to form the ideal nanoparticle film.
ContributorsKline, Katelyn Ann (Author) / Lind, Mary Laura (Thesis director) / Cay, Pinar (Committee member) / Chemical Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2016-12