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Chemistry Department Well Represented at NKU's Annual Celebration of Research and Creativity
On April 10-12, NKU hosted its annual celebration of student research and creativity (Link: celebration home). This year a total of 26 students presentated their sholarly activities in chemistry. Three students gave oral presentations (Link: oral abstracts) while 23 were involved in the presention of 17 posters (Link: poster abstracts) . Oral abstracts
O-1: Matthew Lauer, Areej Saqr Coupling Surface Groups to Dendrimers to Enable Passage Through the Blood Brain Barrier April 10, 2007, 2:10-2:30PM, SC 308 Faculty Sponsor(s): KC Russell, Chemistry & Kristi Martines, Biological Sciences Abstract: The protective lining of the brain known as the blood-brain barrier (BBB), prevents many medications from easily entering the brain. Our research focuses on developing a transport system for various medications by utilizing molecules known to pass though the BBB. These molecules will then be coupled to the surface of generation 4 and 5 polyamidoamine (PAMAM) dendrimers labeled with an Alexa Fluor® 555 dye using a peptide coupling strategy. After the synthesis of such dendrimer conjugates, studies with artificial bilayer membranes and animal models will be used to determine the ability of the conjugates to pass through the BBB.
O-2: Joel Deye Synthesis of a Novel Fullerene-Bipyridine Ligand for Photoelectric Applications April 10, 2007, 2:35-2:55PM, SC 308 Faculty Sponsor(s): Keith Walters, Chemistry Abstract: The objective of this research project is to synthesize a supra-molecular system consisting of a fullerene-bipyridine ligand and a transition metal that will transfer charge when exposed to light. The ligand was successfully coordinated with rhenium, yielding encouraging photochemical results. These results prompt coordination to additional transition metals, such as ruthenium. Once synthesized, a thorough investigation into the photochemical properties of these resulting complexes will be conducted. The target ligand, when coordinated with a metal, could have great potential for uses in solar cells, molecular devices, or other applications where molecules need to “react” with light.
O-3: Celeste Morris New Developments in the Molecular Wire Concept: Structure, Design and Synthesis April 10, 2007, 1:45-2:05PM, SC 308 Faculty Sponsor(s): Keith Walters, Chemistry Abstract: The goal of this molecular wire research is to create a supramolecule which will transfer electrons over a highly conjugated organic polymer. Originally, organic polymers did not successfully incorporate metals due to their linear qualities. This unit will wrap around a metal center thus bringing the metal directly in line with the conjugated polymer backbone, creating a macromolecule, a polymer incorporating metals for the purpose of transferring energy. The advantage of our structure is that interaction of the metal with the surrounding ligands is forced through coordination. This project first requires the synthesis of a series of ligands followed by the synthesis of the final molecular wire subunit. Once achieved, the electron flow from excitation will be optimized and have applications in solar cells, medical devices, computer chips and LEDs. Poster abstractsP-21: Bridget Hemmerle Characterization of Self Assembled Monolayers as Potential Nonbiofouling Surfaces Faculty Sponsor(s): Heather Bullen, Chemistry Abstract: Biofilms form when bacteria adhere to surfaces, such as metal, plastic, medical implants, and tissue. Biofilms on such surfaces can cause equipment damage, product contamination, and medical infections. Conventional methods of killing bacteria or prohibiting the anchoring of the bacteria have proven ineffective. The research presented here investigates the effectiveness of self assembled monolayers (SAMs) to form a non-adhesive coating on gold and stainless steel surfaces. These SAMs may reduce or prevent the adhesion of the microbial bacteria on the surface of these metals.
P-22: Dan Hogan ATR-FTIR and HPLC Analysis of the Interaction of Biotinylated Dendrimers with Blood Brain-Barrier Models Faculty Sponsor(s): Heather Bullen, Chemistry & Kristi Martines, Biological Sciences Abstract: Dendrimers have significant pharmaceutical appeal because their structures provide a possible mechanism for carrying drugs across the blood-brain barrier (BBB). The focus of this research project is the characterization of the interaction of biotinylated G4 and G5 PAMAM dendrimers with model BBBs using attenuated total reflectance infrared spectroscopy (ATR-FTIR) and high performance liquid chromatography (HPLC). Due to the reasonable cost and high binding affinity, avidin and biotin are ideal to use as markers for PAMAM dendrimers. Results on the HPLC and variable angle ATR-FTIR analysis of their interaction with a model BBB, DMPC (Dimyristoyl-sn-Glycero-3-Phosphocholine) liposomes, are presented here.
P-23: Meagan Leist Probing Bacterial Adhesion: Analysis of the Interaction of Hydroxamate Siderophores with Aqueous-Metal Oxide Interfaces Faculty Sponsor(s): Heather Bullen, Chemistry Abstract: Biofilms have a profound impact on industrial, food processing, and medical settings. The role of hydroxamate siderophores in the initial adhesion of bacteria to TiO2, MnO2, and Fe2O3 surfaces has been investigated. Attenuated total-reflectance infrared spectroscopy (ATR-FTIR) of hydroxamate models and atomic spectroscopy have been utilized to understand the binding and dissolution properties of hydroxamate siderophores. Preliminary results indicate that acetohydroxamate binds covalently to the TiO2, MnO2, and Fe2O3 surfaces in a bidentate dianion form.
P-24: Shannon O'Connell Use of a Continuous-flow Chamber to Evaluate Pseudomonas aeruginosa Biofilm Formation on Metal Oxide Surfaces Faculty Sponsor(s): Heather Bullen, Chemistry & Hazel Barton, Biological Sciences Abstract: Bacteria produce metal sequestering proteins known as siderophores which are believed to aid in bacteria adhering to metal oxide surfaces. Because many metals are subject to metal oxide layer formation, bacterial growth is widely problematic. In industry, bacterial growth is a common source of fouling; and, in medicine, bacterial contaminants are potentially fatal. In this research, the process by which Pseudomonas aeruginosa attach to and proliferate on Fe2O3 and TiO2 surfaces will be characterized using a continuous flow biofilm chamber.
P-25: Stephanie Proctor Impact of Pyoverdin Siderophores Extracted from Pseudomonas aeruginosa on Bacterial Adhesion to Metal Oxide Surfaces Faculty Sponsor(s): Heather Bullen, Chemistry & Hazel Barton, Biological Sciences Abstract: Biofilms form when a collection of microorganisms, such as bacteria, immobilize on a surface. Early stages of biofilm adhesion do not account for chemical reactions occurring at the surface of a substrate. This research evaluates the role of siderophores, iron sequestering ligands produced by most bacteria, in the initial biofilm formation. The isolation of pyoverdin (a catecholate siderohpore produced by Pseudomonas aeruginosa) and its interaction with various metal oxide substrates are presented here. Comparison studies between wild type P. aeruginosa and a pvdS mutant, not expressing pyoverdin, provide further insight into ascertaining the role of siderophores in the adhesion process.
P-26: Whitney Schmidt Surface Complexation of Catecholate Siderophore Models on Metal Oxide Surfaces Faculty Sponsor(s): Heather Bullen, Chemistry Abstract: We present here work characterizing the complexation of model siderophores to metal oxide surfaces. The interaction of catecholate derivatives: catechol, 4-nitrocatechol, and 2,3-dihydroxynaphthalene with metal oxide sol-gels: TiO2, MnO2, Fe2O3, and Cr2O3 were monitored as a function of ionic strength and pH. Macroscopic adsorption using high performance liquid chromatography (HPLC) and dissolution measurements utilizing atomic absorbance spectroscopy, graphite furnace (GTA), were conducted, and provide an indication of inner sphere vs. outer sphere complexation. A modified synthesis of Cr2O3 sol-gels, one of the model metal oxides, is also presented.
P-27: Robert Wilson Characterization of Self Assembled Monolayers as Potential Nonbiofouling Surfaces Faculty Sponsor(s): Heather Bullen, Chemistry Abstract: Biofilms are a collection of microorganisms that immobilize on a surface, surrounded by a microbe-induced polymer matrix. Biofilm related problems are prevalent in various industrial and medical settings. The research presented here evaluates the formation of Self Assembled Monolayers (SAMs) on stainless steel (SS) and gold (Au) substrates as potential nonbiofouling surfaces. Electrochemical and scanning probe microscopy (SPM) methods were utilized to characterize model SAMs: 16-mercaptohexadecanoic acid (C16 COOH), 1-hexadecanethiol (C16 CH3), and 1-octadecanethiol (C18 CH3). SAMs formed on 316L SS (a model surface for medical implants) are compared to SAMS on Au.
P-28: Chevelle Cason, J. Daniel Hogan Quantification of PAMAM Functionalized Dendrimer Passage Across in vitro Blood Brain Barrier Models Faculty Sponsor(s): Heather Bullen, Chemistry & Kristi Martines, Biological Sciences Abstract: Customizable nanopolymers have potential as pharmaceutical delivery systems across the blood-brain barrier (BBB). This project is aimed at developing methods to quantify G4/G5 PAMAM dendrimer passage through in vitro models of BBB’s using high performance liquid chromatography (HPLC). Specific methodological factors evaluated include sample matrix, biotinylation, wavelength detection, and mobile phase gradient. Progress with Atomic Force Microscope capture surface will also be addressed.
P-29: Chris Elam Development of an Enzyme Assay Using a Multi-well Plate Reader for the Rapid Screening for Novel ATPase Inhibitors Faculty Sponsor(s): Stefan Paula, Chemistry Abstract: The inhibition of the transmembrane enzyme Sarco/Endoplasmic Reticulum Calcium ATPase (SERCA) has been suggested as a strategy for anticancer chemotherapy. The inhibitory potencies of potential inhibitors can be determined in coupled ATPase inhibition assays that rely on the spectroscopic detection of NADH oxidation. To facilitate the rapid screening of compound databases for novel inhibitors, a miniaturized ATPase inhibition assay on a multi-well plate was developed. This assay permits the simultaneous monitoring of 96 samples, thereby allowing the determination of the IC50 values (a numerical measure for inhibitory potency) of up to eight compounds within only a few minutes.
P-30: Kayla Evans Preparation of Proteoliposomes for the Study of Ion Transport by P-type ATPase Faculty Sponsor(s): Stefan Paula, Chemistry Abstract: Ion transport by the transmembrane protein calcium ATPase can be studied in proteoliposomes that can be obtained by reconstituting the protein into the liposome bilayer. In order to study ion transport of a novel P5-type ATPase, we are using a well-established protocol for the proteoliposome preparation for calcium ATPase, which is closely related to our ATPase. To this end, we have prepared liposomes by extrusion and by detergent solubilization using BioBeads for detergent removal. The proton permeability of these liposomes was measured using the encapsulated pH-indicator pyranine and was found to be low, ruling out the formation of leaky liposomes that would be unsuitable for ion transport studies. Future experiments will characterize the ion transport activity of the reconstituted ATPase using ion-sensitive fluorescent dyes encapsulated inside the proteoliposomes.
P-31: Mike Lape Computational Analysis of Interactions Between Cocaine and an Anti-cocaine Antibody for Immunotherapy of Cocaine Addiction Faculty Sponsor(s): Stefan Paula, Chemistry Abstract: The amino acid sequence for the variable regions of the heavy and light chains of the cocaine binding monoclonal antibody (mAb2E2) were utilized to build a three-dimensional computational model of mAb2E2. The model was then employed in computational docking, to determine the binding pose for each physiologically relevant metabolite. Comparison between the docking results and experimentally derived binding data showed a good correlation thereby validating the accuracy of the computational model. Future work will focus on the prediction of effects of single amino acid mutations in mAb2E2 in order to optimize its binding properties for immunotherapy of cocaine addiction.
P-32: Jason Ferayorni, Matthew Lauer, Jackie Bowman The Synthesis and Spectroscopy of Pyridoannulenes Faculty Sponsor(s): KC Russell, Chemistry Abstract: Pyridoannulenes are molecules that posses triple bonds on either side of a cis-double bond. Pyridoannulene compounds are of interest because of their interesting and unique physical and chemical properties. These compounds are expected to prove invaluable in the design and manufacturing of nanoelectronics, such as molecule size wires, logic gates, LEDs, LCDs, solar cells, and memory storage devices. This poster will discuss the convergent synthesis and spectroscopy of three pyridoannulenes isomers. The spectroscopy studies, UV-Visible and emission, have shown a wide range of interesting and promising results when protonated with trifluoroacetic acid.
P-33: Mark Seger Synthesis and Characterization of Soluble Flavobenzocyclynes Faculty Sponsor(s): KC Russell, Chemistry Abstract: Benzocyclynes are molecules of great interest because they possess unusual chemical and physical properties. These properties are expected to be important in the design and manufacture of nanoelectronic and photonic devices. We have previously synthesized a strongly fluorescent flavobenzocyclyne. Unfortunately, this compound has extremely limited solubility in all types of solvents. The preliminary focus of this project is to prepare soluble derivatives of the fluorescent flavobenzocyclyne. To achieve this, an isobutyl group has been subsituted with the naturally occurring ribityl side chain. This poster will present the progess made in the synthesis of soluble benzocyclyne derivatives.
P-34: Mark Yagodzinski, Ian Barnes, Chelsea Bond, Chris Miller The Role of Connectivity and Conjugation on the Solid-State and Spectroscopic Characteristics of Novel Push-Pull Benzoannulenes. Faculty Sponsor(s): KC Russell, Chemistry Abstract: Two isomeric differentially protected bis-alkynylpyridines will be used along with a dialkoxy benzene to prepare a series of four new diasteriomeric annulenes. Each isomer will have a different orientation of electron donating oxygens with respect to the electron accepting nitrogens. The effect of these differing orientations will result in complexes and spectroscopic properties for each compound. After synthesis, the spectroscopic effects as a function of pH with various metal cations and complexes will be determined,. Results of the experiment can then be compared to the previously synthesized isomers to give a complete picture of how donor-acceptor orientation affect solid-state spectroscopic characteristics.
P-35: Craig Girten, Jody Helton Surface Modification of G4 and G5 PAMAM Dendrimers Faculty Sponsor(s): Keith Walters, Chemistry & Heather Bullen, Chemistry Abstract: The goal of the collaborative dendrimer project at Northern Kentucky University is to synthesize dendrimers capable of crossing the blood-brain barrier for drug delivery. This aspect of the research has focused on dual-functionalizing fourth- and fifth-generation poly(amino)amide (PAMAM) dendrimers with the dansyl chloride fluorophore. The dual-functionalization will ultimately allow for dendrimers to have both fluorescent tags and moieties of interest (e.g., drugs) for future in vitro and in vivo studies.
P-36: Sean Goins, James Kareth, Celeste Morris, Joel Deye, Keith Walters Synthesis of New Symmetric and Asymmetric Systems for Electron Transfer in Supramolecular Systems Faculty Sponsor(s): Keith Walters, Chemistry Abstract: The goal of this research is to successfully synthesize symmetric and asymmetric structures for use in supramolecular modular systems. Stille-Cross Coupling and Sonagashira Coupling will be used to facilitate the syntheses of these products. These modules allow for electrons to be transferred to fullerenes (Carbon-60 structures) and other molecular wire structures.
P-37: Rebecca Seger Synthesis of a New Isocyanide Ligand for Efficient Photo-Induced Charge Transfer Processes Within an Octahedral W(0) Compound. Faculty Sponsor(s): Keith Walters, Chemistry Abstract: Certain tungsten compounds, when excited with a photon of light energy, have been found to be extremely efficient electron donors in redox reactions. To date, however, such tungsten complexes have been inefficient, decomposing quickly at room temperature. The purpose of this research is to synthesize a more robust tungsten complex, which could be used in the treatment of waste water or other chemical reactions that would be driven by sunlight alone. |
