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Undergraduate Research Opportunities Program

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Office of Undergraduate Education

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Now showing 1 - 10 of 34

Studies of a novel drug designed to prevent tumor invasion and metastasis

(Georgia Institute of Technology, 2012-12-18) Slutsky, Audrey Louise

Anti-invasive therapeutics provide a means to improve the prognosis of invasive cancer patients. Recently, one such compound have been identified for its ability to halt the invasion of glioblastoma. This compound, known as Imipramine Blue (IB), successfully reduced cancer cell invasion in vitro and in vivo, and displayed the potential to reduce invasion in other invasive cancer models as well.1 Therefore, it was determined that the effects of IB should be studied in depth on other invasive cancer models, and a metastatic prostate cancer cell line, MatLyLu, was chosen for the study. Prostate cancer, like glioblastoma, has a poor prognosis due to its extremely invasive nature. The primary goal of this project was to determine the ability of IB to halt invasion of the MatLyLu cell line at non-cytotoxic levels. To do this, an in vitro invasion assay was performed on MatLyLu. Preliminary results showed that MatLyLu experiences a dose dependent decrease in invasion, but for this experiment, IB was determined to be cytotoxic. Thus, the invasion assay procedure was then optimized to eliminate cytotoxicity, and any possible human error. The invasive glioblastoma cell line, which has been shown to respond to IB treatment, was also incorporated as a positive control. Another test was performed, and results showed that IB was no longer cytotoxic. However, a dose dependent decrease in invasion was no longer seen for either cell line. The invasion assay procedure was optimized further, and the experiments were performed again. Results from these experiments showed that the RT2 cells do experience a dose dependent decrease in invasion at non-cytotoxic levels. However, the MatLyLu cell line still did not show a dose dependent decrease in invasion. The secondary goal of this project was to develop an in vivo tumor model for MatLyLu. A metastatic model was developed in Copenhagen rats, and the model develops metastases in the lungs 18 days after tumor cell implantation. This model must be tested with Luciferase expressing MatLyLu cells in order to evaluate metastasis non-invasively.
An FPGA-based microarchitecture for the implementation of quantum gates with trapped ions

(Georgia Institute of Technology, 2012-12-18) Nichols, Charles Spencer

Quantum computing promises to revolutionize computing by providing exponential speed improvements to classically difficult problems. Over the past 30 years, experimental research has progressed from manipulating quantum systems to creating elementary gates in many quantum mechanical systems. One of the most successful media for implementing quantum gates is trapped ions. Current trapped-ion quantum computing architectures have very high gate fidelities and long coherence times, but creating quantum gates with low error rates with trapped ions is challenging since it requires precise trap and laser control. In order to implement quantum gates with trapped ions, I have created a field-programmable-gate-array- (FPGA) based microarchitecture for constructing laser-pulse sequences and controlling ancillary equipment. The microarchitecture is centralized to minimize experimental timing errors and is programmable to provide the generality necessary for implementing a vast range of experiments.
Synthesis of a triple-decker π-conjugated system to explore charge migration in organic semiconductors

(Georgia Institute of Technology, 2012-12-18) Castaneda, Alma Delia

Closely stacked π-systems exhibit physical properties that are a consequence of π- π interactions. The primary focus of this study is the production of a triple-decker π-conjugated system. Although many studies have investigated the use of para and meta-cyclophanes, research on ortho-cyclophanes in which arene rings are held in a stacked arrangement has been limited. This thesis describes a synthesis of the scaffold to hold conjugated units together. Ultimately, the stacked analog will be obtained by ketalization of a bicyclic ketone with ethylene glycol to lock the bicyclic core into a chair-chair conformation in which oligo(phenylene ethynylene)s are stacked atop one another. The optical properties of the stacked compound will be studied using UV-Vis and fluorescence spectroscopy. The electrochemical properties of the stacked compounds will be characterized using cyclic voltametry (CV) and differential pulse voltammetry (DPV).
The effect of host food quality on host and parasite fitness in an invertebrate-parasite system

(Georgia Institute of Technology, 2012-12-18) Snell, Sara Jeanne

Parasites achieve their fitness by reducing the fitness of the hosts they infect. The relationship between host and parasite fitness is often mediated by environmental conditions, such as the quality of food consumed by the host. We used the crustacean Daphnia dentifera and its virulent yeast parasite Metschnikowia bicuspidata to examine how the quality of the food consumed by the Daphnia affected the probability of the host being infected by the parasite and the fitness consequences of infection for the host (measured as offspring production and survival) and for the parasite (measured as the production of transmission spores within the host following infection). We fed Daphnia either high quality food (Ankistrodesmus falcatus) or low quality food (Oocystis sp.) before exposure to Metschnikowia spores, and then either high quality or low quality food after parasite exposure (according to a fully factorial design). We found that when hosts were fed high quality food as juveniles and adults, they were able to invest more energy in preventing loss of fitness due to parasites without limiting parasite growth; high quality food therefore benefits both parasite and host. High food quality benefited both host and parasite when hosts are infected. We saw that infected hosts that produced more offspring also contained more parasite spores. One possible explanation for this is the individuals that produced more offspring and spores were larger, allowing them to take in more resources.
High-contrast metal-responsive fluorescent probes based on synergistic electronic and conformational switching

(Georgia Institute of Technology, 2012-12-18) Sarwar, Mysha

We have prepared and characterized a Mg(II)-responsive fluorescent probe, constructed using a large tetradentate, 15-membered crown ether ligand and a 1,3,5-triaryl-substituted pyrazoline fluorophore. The photoinduced electron transfer (PET) driving force between the ligand and fluorophore controls the fluorescence contrast ratio when an analyte is bound to the probe. Previous studies have shown that the maximum obtainable fluorescence probes based on macrocyclic ligands was impaired due to ternary complex formation of the metal-ligand complex with the solvent molecules. We redesigned the metal ion receptor by incorporating the aniline ring into the ligand. We selected four fluoro substituents to increase the electron withdrawing ability of the 1-aryl-ring, yielding a very high fluorescence enhancement upon saturation with Mg(II) in acetonitrile. The quantum yield of this pyrazoline probe was found to be 79%.We expect that the described approach should be applicable for rationally designing high-contrast pyrazoline-based PET probes selective towards other metal cations as well.
Expression and purification of internalin a ligand for internalization studies on non-professional phagocytic epithelial cells

(Georgia Institute of Technology, 2012-12-18) Haddad, Natalie

Infection by intracellular pathogens is a growing concern as these microorganisms can cross their host s cellular barrier and use the host s own cellular proteins for replication, making treatment very difficult (Kenneth et al., 2008). A further restriction for treatment is that a proposed drug must be able to cross the same barriers in order to reach these pathogens. Our study investigates the same protein used by a particular intracellular pathogen, Listeria monocytogenes, as a possible internalization method for intracellular delivery of materials or drugs. A pGEX-6p plasmid vector containing a gene for the bacterial surface protein Internalin A (InlA) and a glutathione S-transferase (GST) tag, was restored and transformed into Escherichia coli MAX Efficiency DH5αF`IQ competent cells in order to increase insert stability and DNA quality. The plasmid was then purified and subsequently transformed into One Shot BL21(DE3)pLysS expression competent E. coli cells. Thereafter, the InlA-GST fusion protein was expressed in the BL21 cells using Isopropyl β-D-1-thiogalactopyranoside (IPTG). It has been shown, through selective plating and gel electrophoresis, that the plasmid was successfully transformed and purified. Our next steps will be to purify the InlA-GST fusion protein using glutathione affinity based chromatography, cleave and remove the GST tag from the InlA protein of interest, fluorescently label InlA using Alexa Flour, and bind InlA to microbeads of various sizes in a range of densities. We will then carry out internalization assays of the InlA-coated beads in different epithelial cell lines to demonstrate the versatility of this method as a possible material or drug delivery option.
Fast and robust cloth simulation

(Georgia Institute of Technology, 2012-12-17) Shin, Michael Young

The goal of this project is to develop a realistic, robust, and fast cloth-simulator - realistic and robust, so that the clothes behave as expected; and fast, so that results can be seen instantly and the clothes can be interacted with in real-time. A variety of papers on previous works are referenced, so that the specific advancements of each research may be combined to produce the desired simulator. The long-term intention of this project is to serve as the requisite physical engine in which a protocol for the animation of digital characters putting on clothes may be developed. This has applications in robotics, wherein the protocol used by the digital character can be taught to robots, which may then help people who have difficulty dressing themselves.
Amazon River influence on nitrogen fixation and export production in the western tropical north Atlantic

(Georgia Institute of Technology, 2012-12-17) Weber, Sarah Catherine

As part of the multidisciplinary ANACONDAS program, we characterized the distributions of nutrients, particulate organic matter, phytoplankton, and stable carbon and nitrogen isotopes in the Amazon plume region during the spring high-flow period of May-June 2010. We encountered the lowest salinities (16.6 psu) near the southern end of our study region where the plume showed the greatest spatial coherence, and the highest salinities (36.0 psu) to the east of the plume. The major nutrients showed distinct patterns of variation with salinity, with NO₃- largely absent from the surface plume and SiO₂ and PO₄³⁻ showing different degrees of conservative behavior. SiO₂ distributions were more strongly conservative, but with clear negative deviations that reflected biological consumption. In contrast, PO₄³⁻ concentrations showed clear positive deviations as large as 0.7 µM across a broad range of salinities as particle- and organically-bound P was released. These nutrient distributions resulted in strong nitrogen limitation and delivery of substantial amounts of SiO₂ and PO₄³⁻ to offshore waters, creating conditions that favored diazotrophy rather than simple eutrophication. We found a variety of diazotrophs in our study area, with interesting regional variation in their distributions. Mesohaline waters to the northwest of the plume axis were strongly dominated by Diatom-Diazotroph Associations (DDAs), particularly the Hemiaulus hauckii Richelia intracellularis association. In contrast, Trichodesmium spp. were most abundant to the southeast of the plume. These two diazotrophs appeared to contribute to the nitrogen and carbon budgets of the upper water column in fundamentally different ways, with H. hauckii making a much greater contribution to the particulate nitrogen pool than Trichodesmium spp. (100% versus 50%, respectively), while contributing to a greater reduction in pCO₂ in the upper water column. These contrasts have important implications for the fate of new production, with DDAs supporting higher export flux than Trichodesmium spp. Our findings provide an important constraint on the role of the Amazon plume in creating distinct niches for diazotrophic phytoplankton, and for their role in the nutrient and carbon budgets of the Western Tropical North Atlantic
Ecological implications and identification of a freshwater red alga chemical defense

(Georgia Institute of Technology, 2012-08-01) Nahabedian, John F., III

Aquatic generalist herbivores feed selectively when offered several species of macrophytes, preferring more nutritious macrophytes and those with minimal chemical or physical defense. This selective feeding plays an important role in structuring plant communities, sometimes completely altering communities of aquatic plants. While it is known that higher plants in freshwater systems produce chemical defenses against herbivores, the chemical deterrents themselves have rarely been identified, and none are known for freshwater red algae. Batrachospermum helminthosum, a freshwater red alga, exhibits evidence of chemical deterrents to feeding by crayfish. In this experiment, we evaluated whether crayfish unwillingness to consume B. helminthosum was due to morphological or structural feeding deterrents by drying, powdering, reconstituting the alga into sodium alginate gel pellets and offering these, versus pellets made with a different, palatable alga to crayfish. Crayfish consumed pellets made from the green alga Cladophora glomerata in preference to pellets made from B. helminthosum, suggesting that chemical rather than structural traits were responsible for crayfish selective feeding. Bioassay-guided fractionation and the application of proton NMR, carbon-13 NMR, liquid chromatography mass spectrometry (LCMS), and high resolution mass spectroscopy were used to attempt to isolate and identify the chemical compounds responsible for B. helminthosum herbivore defenses. We found evidence of several chemical deterrents ranging from polar to non-polar. Candidate molecular weights for one or two compounds in the most purified, active fraction were 339.5 and 268.2.
Synthesis of crosslinkable hole transporting polymers for organic light emitting diodes (OLEDs)

(Georgia Institute of Technology, 2012-05-10) Coropceanu, Igor

As a result of intensive research over the course of the past decade and beyond, great strides have been made in developing organic light emitting diodes (OLEDs) for display and solid-state lighting applications. One of the key remaining obstacles to OLED production is the difficulty of fabricating the multi-layer architecture required for high-performance devices. Vacuum deposition, the conventional fabrication approach is expensive and is not readily scalable, while the main alternative approach - solution processing is hindered by inter-layer incompatibilities. A promising answer to the latter issue involves rendering each layer insoluble after deposition by inducing crosslinking, thus making the material compatible with the next layer deposited above it. The goal of this project was the preparation of novel crosslinkable materials for applications as the hole-transport layer (HTL) in OLEDs. A series of copolymers was prepared, integrating a hole transport group on one chain and a crosslinker on the other. The crosslinking groups studied were benzocyclobutene (BCB), oxetane (OXT), and trifluorovinyl ether (TFVE). Thin films of the target materials were prepared, processed to induce crosslinking, and their solvent resistance was evaluated. It was found that materials incorporating BCB and OXT groups exhibited effective solvent resistance, even after relatively short processing times.