Matching Items (14)
Filtering by
- All Subjects: E. coli
- All Subjects: Hydrogels
- Creators: Chemical Engineering Program
- Creators: Holloway, Julianne
Description
In a dormant state, cancer cells survive chemotherapy leaving the opportunity for cancer cell relapse and metastasis ultimately leading to patient death. A novel aminoglycoside-based hydrogel ‘Amikagel’ developed in Dr. Rege’s lab serves as a platform for a 3D tumor microenvironment (3DTM) mimicking cancer cell dormancy and relapse. Six Amikagels of varying mechanical stiffness and adhesivities were synthesized and evaluated as platforms for 3DTM formation through cell viability and cell cycle arrest analyses. The impact of fetal bovine serum concentration and bovine serum albumin concentration in the media were studied for their impact on 3DTM formation. These experiments allow us to identify the best possible Amikagel formulation for 3DTM.
ContributorsGjertsen, Haley Nicole (Author) / Rege, Kaushal (Thesis director) / Grandhi, Taraka Sai Pavan (Committee member) / Chemical Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2016-05
Description
Depletion of fossil fuel resources has led to the investigation of alternate feedstocks for and methods of chemical synthesis, in particular the use of E. coli biocatalysts to produce fine commodity chemicals from renewable glucose sources. Production of phenol, 2-phenylethanol, and styrene was investigated, in particular the limitation in yield and accumulation that results from high product toxicity. This paper examines two methods of product toxicity mitigation: the use of efflux pumps and the separation of pathways which produce less toxic intermediates. A library of 43 efflux pumps from various organisms were screened for their potential to confer resistance to phenol, 2-phenylethanol, and styrene on an E. coli host. A pump sourced from P. putida was found to allow for increased host growth in the presence of styrene as compared to a cell with no efflux pump. The separation of styrene producing pathway was also investigated. Cells capable of performing the first and latter halves of the synthesis were allowed to grow separately and later combined in order to capitalize on the relatively lower toxicity of the intermediate, trans-cinnamate. The styrene production and yield from this separated set of cultures was compared to that resulting from the growth of cells containing the full set of styrene synthesis genes. Results from this experiment were inconclusive.
ContributorsLallmamode, Noor Atiya Jabeen (Author) / Nielsen, David (Thesis director) / Cadillo-Quiroz, Hinsby (Committee member) / Barrett, The Honors College (Contributor) / Chemical Engineering Program (Contributor) / School of Life Sciences (Contributor)
Created2015-05
Description
The goals of the styrene oxide adsorption experiments were to develop reliable isotherms of styrene oxide onto Dowex Optipore L-493 resin and onto mesoporous carbon adsorbents, in addition to determining the ideal conditions for styrene oxide production from E. coli. Adsorption is an effective means of separation used in industry to separate compounds, often organics from air and water. Styrene oxide adsorption runs without E. coli were conducted at concentrations ranging from 0.15 to 3.00 g/L with resin masses ranging from 0.1 to 0.5 g of Dowex Optipore L-493 and 0.5 to 0.75 g of mesoporous carbon adsorbent. Runs were conducted on a shake plate operating at 80 rpm for 24 hours at ambient temperature. Isotherms were developed from the results and then adsorption experiments with E. coli and L-493 were performed. Runs were conducted at glucose concentrations ranging from 20-40 g/L and resin masses of 0.100 g to 0.800 g. Samples were incubated for 72 hours and styrene oxide production was measured using an HPLC device. Specific loading values reached up to 0.356 g/g for runs without E. coli and nearly 0.003 g of styrene oxide was adsorbed by L-493 during runs with E. coli. Styrene oxide production was most effective at low resin masses and medium glucose concentrations when produced by E. coli.
ContributorsHsu, Joshua (Co-author) / Oremland, Zachary (Co-author) / Nielsen, David (Thesis director) / Staggs, Kyle (Committee member) / Barrett, The Honors College (Contributor) / Chemical Engineering Program (Contributor) / School of Sustainability (Contributor)
Created2014-05
Description
The purpose of this project is to investigate the swelling ratio exhibited due to photothermal effects of double network polyacrylamide poly(acrylic acid) hydrogels synthesized with carbon black as a light-sensitive chromophore. Optimal carbon black dispersion was achieved in solutions through sonication, using V9A32 carbon black, where dynamic light scattering recorded particle diameters in the range of 195.0-375.8 nanometers for water/carbon black mixtures, 242.4-262.6 nanometers for monomer/carbon black mixtures without initiator, and 1109.3-1783.9 nanometers for monomer/carbon black mixtures including initiator. The double network polyacrylamide poly(acrylic acid) hydrogels with carbon black yielded weight increases of 0.126% and 6.043%, respectively, after 2 minutes and 10 minutes of being exposed to a light stimulus; compared to previous work which showed a double network polyacrylamide poly(acrylic acid) hydrogel with chlorophyllin yielded weight increases of 18.3% and 20.8%, respectively, after 2 minutes and 10 minutes of being exposed to a light stimulus, the carbon black resulted in a less robust response. Future work for application of the light-responsive hydrogels includes the development of a screen covering that will be made of the hydrogels. This covering is intended for use on LED screen displays, where a light change will result in a protrusion from the screen. The purpose behind this application is that technology users who are visually impaired can still determine what their LED device is trying to communicate with them.
ContributorsReimann, Morgan Elizabeth (Co-author) / Yifei, Xu (Co-author) / Dai, Lenore (Co-author, Thesis director) / Xu, Yifei (Committee member) / Chemical Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2017-05
Description
The inability of a single strain of bacteria to simultaneously and completely consume multiple sugars, such as glucose and xylose, hinder industrial microbial processes for ethanol and lactate production. To overcome this limitation, I am engineering an E. coli co-culture system consisting of two ‘specialists'. One has the ability to only consume xylose and the other only glucose. This allows for co-utilization of lignocellulose-derived sugars so both sugars are completely consumed, residence time is reduced and lactate and ethanol titers are maximized.
ContributorsAyla, Zeynep Ece (Author) / Nielsen, David (Thesis director) / Flores, Andrew (Committee member) / Chemical Engineering Program (Contributor) / School of Sustainability (Contributor) / Barrett, The Honors College (Contributor)
Created2017-05
Description
A growing number of stylists \u2014 cosmetologists \u2014 are finding it harder to afford the basic necessities such as rent. However, the ever-increasing presence of smartphones and the increasing need for on-demand services like Uber and Uber Eats creates a unique opportunity for stylists \u2014 Clippr. Clippr is an application that aims to connect individual stylists directly to their customers. The application gives stylists a platform to create and display their own prices, services, and portfolio. Customers get the benefit of finding a stylist that suits them and booking instantly. This project outlines the backend for the Clippr application. It goes over the framework, REST API, and various functionalities of the application. Additionally, the project also covers the work that is still needed to successfully launch the application.
ContributorsKamath, Sanketh (Author) / Olsen, Christopher (Thesis director) / Sebold, Brent (Committee member) / Chemical Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2017-05
Description
Escherichia coli is a bacterium that is used widely in metabolic engineering due to its ability to grow at a fast rate and to be cultured easily. E. coli can be engineered to produce many valuable chemicals, including biofuels and L-Phenylalanine—a precursor to many pharmaceuticals. Significant cell growth occurs in parallel to the biosynthesis of the desired biofuel or biochemical product, and limits product concentrations and yields. Stopping cell growth can improve chemical production since more resources will go toward chemical production than toward biomass. The goal of the project is to test different methods of controlling microbial uptake of nutrients, specifically phosphate, to dynamically limit cell growth and improve biochemical production of E. coli, and the research has the potential to promote public health, sustainability, and environment. This can be achieved by targeting phosphate transporter genes using CRISPRi and CRISPR, and they will limit the uptake of phosphate by targeting the phosphate transporter genes in DNA, which will stop transcriptions of the genes. In the experiment, NST74∆crr∆pykAF, a L-Phe overproducer, was used as the base strain, and the pitA phosphate transporter gene was targeted in the CRISPRi and CRISPR systems with the strain with other phosphate transporters knocked out. The tested CRISPRi and CRISPR mechanisms did not stop cell growth or improved L-Phe production. Further research will be conducted to determine the problem of the system. In addition, the CRISPRi and CRISPR systems that target multiple phosphate transporter genes will be tested in the future as well as the other method of stopping transcriptions of the phosphate transporter genes, which is called a tunable toggle switch mechanism.
ContributorsPark, Min Su (Author) / Nielsen, David (Thesis director) / Machas, Michael (Committee member) / Chemical Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2018-05
Description
Membrane proteins are essential for cell survival and show potential as pharmacological and therapeutic targets in the field of nanobiotechnology.[1,2] In spite of their promise in these fields, research surrounding membrane proteins lags since their over-expression often leads to cell toxicity and death.[3,4] It was hypothesized that membrane protein expression could be regulated and optimized by modifying the heat shock response of Escherichia coli (E. coli). To test this hypothesis, the membrane protein expression pathway was reprogrammed using gene-blocks that were antisense to vital membrane protein DNA and RNA binding-site sequences and included an IbpA-σ32 heat shock promoter. Anti-PBAD and anti-HtdR gene-blocks were designed to have antisense sequences to the DNA of the arabinose PBAD promotor and Haloterrigena turkmenica deltarhodopsin (HtdR) transmembrane protein respectively. These sequences were then employed to be cloned into a pMM102 vector and grown in NEB-5α E. coli cells.
Stable glycerol stocks of the pIbpA-antiPBAD and pIbpA-antiHtdR in BW25113 cells with either a pBLN200 or pHtdR200 plasmid were created. Then after inducing the cells with L-arabinose and 10mM all-trans retinal to allow for membrane protein expression, spectrophotometry was used to test the optical density of the cells at an absorbance of 600nm. Although general trends showed that the pHtdR200-pMM102 and pHtdR200-pIbpA cells had lower optical densities than the pBLN200 cells of all types, the results were determined to be statistically insignificant. Continuing, the pHtdR200 cells of all types showed a purple phenotype when spun down, as expected, while the cells with the pBLN200 plasmid had a colorless phenotype in pellet form. Further work will include cloning a GFP gene-block to test the ability of the anti-PBAD sequence in tuning the transcription of the GFP protein.
Stable glycerol stocks of the pIbpA-antiPBAD and pIbpA-antiHtdR in BW25113 cells with either a pBLN200 or pHtdR200 plasmid were created. Then after inducing the cells with L-arabinose and 10mM all-trans retinal to allow for membrane protein expression, spectrophotometry was used to test the optical density of the cells at an absorbance of 600nm. Although general trends showed that the pHtdR200-pMM102 and pHtdR200-pIbpA cells had lower optical densities than the pBLN200 cells of all types, the results were determined to be statistically insignificant. Continuing, the pHtdR200 cells of all types showed a purple phenotype when spun down, as expected, while the cells with the pBLN200 plasmid had a colorless phenotype in pellet form. Further work will include cloning a GFP gene-block to test the ability of the anti-PBAD sequence in tuning the transcription of the GFP protein.
ContributorsBoese, Julia Nicole (Author) / Nannenga, Brent (Thesis director) / Holloway, Julianne (Committee member) / Chemical Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2018-05
Description
Four enzymes, ATF1, ATF2, ATF, and CAT, were screened to determine which would be most effective at catalyzing the formation of aromatic esters. The CAT enzyme successfully catalyzed the reaction to produce 2-phenethyl acetate using 20x more lysate to improve the probability of enzyme presence in the lysate. The CAT enzyme was able to catalyze the reaction producing concentrations that increased by 62% every 12 hours. Enzymatic activity resulted in the production of 2.15 mg/L of 2-phenethyl acetate at 12 hours, 5.62 mg/L of 2-phenethyl acetate at 24 hours, and 15.12 mg/L of 2-phenethyl acetate at 48 hours.
ContributorsBrown, Kristen Ashley (Author) / Nielsen, David (Thesis director) / Thompson, Brian (Committee member) / Chemical Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2016-05
Description
Plasmid DNA (pDNA) purification has been extensively investigated for various biological and biochemical applications such as transfection, polymerase chain reaction and DNA therapeutics. In the previous paper, we have described the synthesis, characterization and evaluation of microbeads (“Amikabeads”) derived from aminoglycoside amikacin for pDNA binding via anion-exchange chromatography. Here, we investigated the pDNA binding performance of conjugating Amikabeads with two highly specific DNA binding ligands via minor groove hydrophobic interaction. The pDNA maximum binding capacity of doxorubicin drug-conjugated Amikabeads (“doxo-beads”) was found out to be 429 μg pDNA/ mg of doxo-beads with a Langmuir constant of 8.21*10-4 L/mg, whereas the binding performance of berenil drug-conjugated "mikabeads (“berenil-beads”) was 142 μg pDNA/mg of berenil-beads with a adsorption constant of 4.71*10-5 L/mg. In addition, the desorption percentage of doxo-beads and berenil-beads was obtained as 52% and 41%, respectively. Our results indicate that by conjugating with highly specific DNA binding ligands, Amikabeads-drug complex enhances the pDNA binding performance and contains a promising potential for future applications in biotechnology field.
ContributorsLin, Nan (Author) / Rege, Kaushal (Thesis director) / Grandhi, Taraka Sai Pavan (Committee member) / Chemical Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2016-05