Browsing by Author "University of Minnesota Duluth. Department of Chemistry and Biochemistry"
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Item 25th Annual Spring Symposium (2023-04-22)(2023) University of Minnesota Duluth. Department of Chemistry and BiochemistryItem 3-D Printing of Anatomically-Accurate and Physiologically-Relevant Heart Models for Bioprosthetic Valve Testing (2020-01-31)(2020) Lai, Victor; University of Minnesota Duluth. Department of Chemistry and BiochemistryTranscatheter aortic valve replacement (TAVR) to treat severe aortic stenosis has exceeded the number of surgical aortic valve replacements done in the United States, because of its higher rates of success and lower risk of mortality, especially in older patients. While TAVR valves can achieve immediate relief of obstruction, complications such as aortic rupture and conduction abnormalities such as complete heart block may still occur, which require additional treatment. While it is believed that such valve complications may be exacerbated by pre-existing conditions, the underlying mechanisms causing such failures has not been well studied. In addition, there is currently no method to test the effectiveness of these valves under conditions that are specific to the patient. By applying a combination of Chemistry, Materials Science, and Engineering concepts, we want to develop a proof-of-concept of a 3-D printed heart model for bioprosthetic valve testing that is anatomically-accurate and physiologically-relevant to a patient and his/her underlying condition. The central hypothesis is that the effectiveness of such implants is influenced by the growth and remodeling of the surrounding native tissue in response to localized changes to the micromechanical and fluid flow environment due to the stented valve; understanding such changes to the cellular microenvironment will guide the design of TAVR implants to reduce the incidence of complications.Item Advances in Ionic Liquid-Based Stationary Phases and Sorbent Materials for Chromatography and Sample Preparation (2020-02-07)(2020) Anderson, Jared; University of Minnesota Duluth. Department of Chemistry and BiochemistryIonic liquids (ILs) can be designed to exhibit unique properties for their use in a number of applications in analytical and bioanalytical chemistry. This talk will focus on the design and synthesis of ILs, magnetic ionic liquids (MILs), and polymeric ionic liquids (PILs) as well as the use of these materials in a number of applications within multidimensional chromatography and sample preparation. A series of monocationic/dicationic ionic liquid-based and silver-containing stationary phases were evaluated as secondary columns in comprehensive two-dimensional gas chromatography (GCxGC) for the separation of aliphatic hydrocarbons from kerosene as well as the separation of olefins from paraffins. Finally, nucleic acids are biopolymers that constitute important diagnostic molecules for a broad range of applications from clinical testing to forensic analysis. A major challenge faced by DNA and RNA analysis techniques is the selective extraction of particular nucleic acid sequences using rapid and sensitve methodologies. It will be shown that ion-tagged oligonucleotides (ITOs) can be used in conjunction with MILs to efficiently capture DNA sequences from complex samples. The ITOs can be created through thio-lene "click" chemistry and the nature of the ion tag can influence the partitioning of the ITO to the hydrophobic MIL. This novel liquid-phase approach towards sequence-selective DNA capture provides superior extraction efficiencies to conventional magnetic bead technology as well as a platform for using external fields to manipulate the liquid droplets.Item Applications of Synthetic Chemistry: From Biomaterials and Environmental Science to Molecular Electronics (2021-10-08)(2021) Banks, Surya; University of Minnesota Duluth. Department of Chemistry and BiochemistryThe extent of synthetic organic chemistry is pervasive in every aspect of our society today. However, this applied science is no longer exclusive to one laboratory and has evolved into an exciting multidisciplinary and collaborative quest of our material environment. This talk touches upon some of the interdisciplinary collaborative research projects ranging from a viable proof of chemically modified alginate microcapsules as controlled drug delivery mediums, to search for structure activity relationships on rectification ratios of self-assembled monolayers of benzalkylsilanes on SiO2 substrate. Projects on use of chemically modified biopolymers for environmental chemistry and organometallic oligomers/polymers with potential optoelectronic applications will also be highlighted.Item Aqueous Photochemistry of Polyolefins (2020-02-28)(2020) Mundhenke, Thomas; University of Minnesota Duluth. Department of Chemistry and BiochemistryPolypropylene (PP) and polyethylene (PE) are commonly used polyolefins in a variety of applications, which have resulted in their accummulation in the environment. Once in the environment, these polymers undergo various chemical and physical transformations as the result of environmental stressors such as sunlight. During photodegradation, PP and PE undergo reactions such as oxidation, crosslinking, and chain scission that are induced from UV light; yet, there are key gaps in knowledge on the phototransformations that occur under aqueous conditions. Therefore, it is the goal of this project to characterize the phototransformations of PP and PE in simulated natural water conditions. This presentation focuses on 25 µm thick PP films. The polymer films were irradiated with 254 nm and 350 nm UV light in air, ultra-pure water, and solutions of dissolve organic matter (DOM) (10 mgC/L Suwanee River natural organic matter) to simulate natural systems. For comparison, the films were subjected to natural weathering over the course of Summer 2019 in Duluth, Minnesota. Irradiated plastics were then evaluated for a variety of chemical transformations. It was observed using Fourier Transform Infrared Spectroscopy (FTIR) that oxidation occurred both in air and aqueous environments, with oxidation in aqueous environments happening at a slower rate. Using gel fraction analysis crosslinking was observed to occur in both air and aqueous environments with a lower crosslinking fraction occurring in aqueous environments. Polymer crystallinity was also monitored using FTIR. An increase in crystallinity was observed for all samples indicating that the polymer matrix was rearranged during photodegradation. Through this work, we have gained a more clear perspective on the chemical weathering of materials found in aquatic plastic debris, which will allow us to predict the behavior of these materials, including the breakdown into microplastics.Item Assessing the Degradation of Munitions Compounds by Compound Specific Isotope Analysis in Natural and Engineered Environments (2021-11-19)(2021) Berens, Matthew; University of Minnesota Duluth. Department of Chemistry and BiochemistryIron-bearing minerals are important reductants in the contaminated subsurface, but their availability for the reduction of anthropogenic pollutants is often limited by competition with other electron acceptors including microorganisms and poor accessibility to Fe(II) in complex hydrogeologic settings. The supply of external electron donors through in situ chemical reduction (ISCR) has been proposed as one remediation approach, but the quantification of pollutant transformation is complicated by the perturbations introduced to the subsurface by ISCR. Here, we evaluate the application of compound specific isotope analysis (CSIA) for monitoring the reduction of 2,4-dinitroanisole (DNAN), a component of insensitive munitions formulations, by mineral-bound Fe(II) generated through ISCR of subsurface material from two field sites. Electron balances from laboratory experiments in batch and column reactors showed that 3.6% to 11% of the total Fe in the sediments was available for the reduction of DNAN and its partially reduced intermediates after dithionite treatment. The extent of DNAN reduction was successfully quantified from its N isotope fractionation measured in the column effluent based on the derivation of a N isotope enrichment factor, ?N, derived from a comprehensive series of isotope fractionation experiments with numerous Fe(II)-bearing minerals as well as dithionite-reduced subsurface materials. Our observations illustrate the utility of CSIA as a robust approach to evaluate the success of in situ remediation through abiotic contaminant reduction.Item Asymmetrical Boron-Based Light-Emitting Compounds Based on Aromatic Diamine Frameworks (2022-04-08)(2022) Ploeger, Ethan; University of Minnesota Duluth. Department of Chemistry and BiochemistryIn recent years OLED technology has become very popular for its vibrant colors. The use of OLED allows users to create fluorescent organic compounds without the use of heavy metals. Our work explores chelating ligand frameworks of the kind HO••N that are based on asymmetrical aromatic diamine frameworks that are attached to boron fragments such as BF2 and PPh2. The ligand synthesis is done through condensation reactions and the further reaction with diphenylborinic acid or with BF3 by reaction with BF3•Et2O leads to the final boron-containing products. The final boron derivatives are characterized by NMR, LC-MS, and UV-Vis. The status of current findings in synthesis and characterization as well as light emission data will be presented as well as future plans outlined.Item Biology and Biochemistry in Craft Beverage Distilling (2023-03-03)(2023) Vikre, Emily; University of Minnesota Duluth. Department of Chemistry and BiochemistryItem Breakdown of Plastics in the Environment: The Impact of Weathering on the Fate and Transformations of Aquatic Plastic Debris (2020-10-09)(2020) Maurer-Jones, Melissa; University of Minnesota Duluth. Department of Chemistry and BiochemistryPlastics are a ubiquitous part of everyday life and a central challenge in the environment. Environmental stresses such as sunlight, temperature fluctuations, wet/dry cycling or microbial forces affect the longevity or degradation of plastics. Assessing the fate of plastics under these stresses allows us to accurately predict the service lifetime of plastics used in infrastructure (e.g., power cabling/solar panels) or evaluate the extent of the plastic pollution problem. This talk details the work of quantifying photochemical and thermal degradation mechanisms of plastics commonly found in aquatic plastic debris: polyethylene, polypropylene and polyethylene terephthalate. In this talk, I will focus on the development of a methodological framework for characterization of the rates and yields of the chemical transformations within polymers, moving beyond traditional materials characterization techniques. Additionally, we quantified the formation of microplastics upon photochemical weathering, applying our understanding of the chemical photo-transformations. Beyond the transformations of the plastics, we also began to unravel the role plastics and plastic weathering play on the ecosystem health by monitoring the sorption of model micropollutants to weathered plastics and the toxicity of nanoplastics to a model bacterium. Ultimately, this work strives to quantify the transformations and fate of plastics so as to design a predictive model of plastic behavior in the environment, which has implications for accurately assessing the burden of plastics on the environment but also allows for new polymer design.Item Building Maps of Plant Surface Chemistry Using Literature and Citizen-Collected Mass Spectrometry Samples (2022-03-18)(2022) Nguyen, Dien; University of Minnesota Duluth. Department of Chemistry and BiochemistryPlant cultivation is a crucial part of society. Understanding plant chemicals can greatly help the important goals of reducing negative environmental impacts of agriculture and achieving high crop yields. One class of chemicals that has a big influence on plant health and growth is triterpenoids. However, there is a limited number of biological systems in which to study triterpenoids in detail. To increase the number of study systems, and thus our potential to build knowledge of triterpenoid function, there is a critical need to understand which triterpenoids can be found on which plant species' surface. The objective of this project is to build three “maps" of plant surface compound presence with an emphasis on triterpenoids using published and newly acquired gas chromatography-mass spectrometry data.Item BURST and SURP Poster Presentations (2021-08-06)(2021) University of Minnesota Duluth. Department of Biology; University of Minnesota Duluth. Department of Chemistry and BiochemistryStudents in the Biology Undergraduate Research in Science and Technology (BURST) and the Chemistry and Biochemistry Summer Undergraduate Research Program (SURP) will present the research they have been working on with faculty mentors throughout the summer. There will be an awards ceremony for both programs to follow.Item Characterization of Porous Polyvinylidene Fluoride for Use as a Biosensor (2021-03-05)(2021) Danley, Matt; University of Minnesota Duluth. Department of Chemistry and BiochemistryThe Transcatheter Aortic Valve Replacement (TAVR) is a minimally invasiveprocedure that has grown in popularity in recent years. However, there has beendocumentation of many complications after this procedure, such as a mortality rate of8.4% for TAVR procedures compared to 4.8% for tissue surgery procedures after 90days for Medicare beneficiaries. The underlying mechanisms of the TAVR procedureand how the replacement valve changes the biomechanical and flow environmentafter implantation has not been well studied. Therefore, it is necessary to design amodel heart and create sensors to understand the underlying mechanisms of theTAVR procedure. The goal of this project is to design a sensor that can detectchanges in blood pressure and blood flow rates in a silicon model heart. Onepromising type of material is piezoelectric sensors. Piezoelectric materials takemechanical stress and create detectable changes in voltage that can be calibrated todetermine changes in pressure. One material that has been used for other sensors isPolyvinylidene fluoride (PVDF). This study will investigate how porosity of PVDFchanges the structural and mechanical properties of the polymer. Pores will beintroduced into the PVDF membrane by adding Zinc Oxide (ZnO) nanoparticlesduring the synthesis process and removing the ZnO particles once the membranehas dried. To study the changes in the structure of the membrane, Scanning ElectronMicroscopy is used to confirm a porous structure. To study how the chainconformation of the polymer changes with porosity, Fourier Infrared Spectroscopy isutilized. A Tensile Tester is used to apply compressive stress onto the PVDFmembranes to study the piezoelectric output. To allow for comparison betweenvarious porous membranes, the d33 coefficient is calculated. This will help determinewhich porosity is optimal for the creation of the biosensor with desired sensitivity.Item Characterizing Proteinase K in the Enzymatic Hydrolysis of Photodegraded Polylactic Acid (2023-03-24)(2023) Brown, Maggie; University of Minnesota Duluth. Department of Chemistry and BiochemistryItem Characterizing the Changes to Protein Sorption to Photodegraded Polyethylene (2021-04-09)(2021) Fawcett, Liam; University of Minnesota Duluth. Department of Chemistry and BiochemistryAft er their entry into the environment, plastics are exposed to a multitude ofabiotic environmental factors that change both their physical and chemicalcharacteristics. While the initiation of biotic degradation on pristine polymershas been reviewed, it is generally accepted that biotic degradation is enhancedon polymers that initially have undergone some sort of abiotic degradation,particularly photodegradation. This work seeks to understand the intricacies ofbacterial interactions with plastics by investigating the interaction of proteins topolymers with increasing extents of photodegradation, which should giveinsight into the potential attachment and biofilm formation on plastic debrismaterials. Using bovine serum albumin (BSA) as a model protein, we haveinitially investigated the changes in structural characteristics and fluorescenceof the model protein as it adsorbs onto the surface of irradiated polyethylene.Changes to the secondary structure characteristics of BSA were monitoredthrough circular dichroism and preliminary data has shown that with anincrease in irradiation time, there is a characteristic shift of the 3.6 ?-helices tomore tightly wound 3.10 ?-helices. This is likely due to the increasedhydrophilicity of photodegraded polymers causing the hydrophobic residues towind more tightly. Fluorescence of the tryptophan’s in BSA shows a decreasewith exposure to the polymers regardless of irradiation time, indicating potentialfluorescence quenching from the surface of the polymer. Overall, these resultsindicate that an increase polyethylene irradiation time causes an increase ininteraction strength between the polymer and protein, which may explain howbiotic degradation is increased with abiotically degraded polymers. Ultimatelythis work will contribute to our understanding of the fate of plastics in theenvironment.Item Computational Analysis on a Set of Novel BET Inhibitors Bound to Human BRD4 (2020-02-14)(2020) Jones, Peter; University of Minnesota Duluth. Department of Chemistry and BiochemistryBromodomain-Containing Protein 4 (BRD4) is a human transcriptional regulator and member of the N-Terminal Bromodomain and Extra Terminal Domain (BET) family of proteins. BRD4 binds to acetylated chromatin, preserving epigenetic modifications in the chromatin structure and activating the positive transcription elongation factor (p-TEFb) complex. This complex phosphorylates RNA polymerase II and promotes transcription of the immediate downstream genomic element. BRD4 shows promise as a target for anticancer therapies, with most research focusing on a class of drugs known as BET inhibitors. These drugs bind to the active site of BET family proteins, preventing BRD4 specifically from associating with chromatin. However, there is a lack of atomistic understanding regarding the binding of these drugs to BET family members. Many factors which influence the binding affinity of a series of 1,2,3-triazole-based dual kinase-bromodomain inhibitors bound to the active site of BRD4 have yet to be characterized. Further, the effects of those inhibitors on the structural waters intrinsic to BRD4 remains unclear. Experimental work has suggested that the IC50 of this series of BET inhibitors could be explained in terms of a few specific interactions in the binding site. In this analysis, Free Energy Perturbations (FEP) are used to probe the relative free energy of binding for this set of differentially substituted BET inhibitors. Our working hypothesis is that the chlorine, bromine, and iodine substitutions participate in a halogen bond with the backbone oxygen of MET105 in BRD4, stabilizing the drug in the active site. Further, we propose that substitutions which cannot form this halogen bond, such as fluorine and other nonhalogen substitutions, would have a higher free energy of binding. FEP analysis revealed that the chlorinated, brominated, and iodinated substitutions displayed a lower free energy of binding than the other substitutions, with evidence of a halogen bond between the drug and the backbone oxygen of Met105. It was also observed that this set of BET inhibitors displaces several highly coordinated solvent molecules in the active site of BRD4. By contrast, a simulation of BRD4 complexed with JQ1, another known BET inhibitor, does not displace these waters. These results support our hypothesis that a halogen bond is formed between the large halogen substitutions and the protein, increasing binding affinity for substitutions that can participate in this type of interaction. This halogen bond can be exploited for improving this set inhibitors and designing novel compounds which bind more favorable to BRD4.Item Department of Chemistry and Biochemistry Seminar Schedule 2006 Fall(2006-10-30) University of Minnesota Duluth. Department of Chemistry and BiochemistryItem Department of Chemistry and Biochemistry Seminar Schedule 2007 Fall(2007) University of Minnesota Duluth. Department of Chemistry and BiochemistryItem Department of Chemistry and Biochemistry Seminar Schedule 2007 Spring(2007-02-07) University of Minnesota Duluth. Department of Chemistry and BiochemistryItem Department of Chemistry and Biochemistry Seminar Schedule 2008 Spring(2008-01-14) University of Minnesota Duluth. Department of Chemistry and BiochemistryItem Department of Chemistry and Biochemistry Seminar Schedule 2009 Fall(2009-09-30) University of Minnesota Duluth. Department of Chemistry and Biochemistry