Chemistry Commons^™

Electronic Transport Properties Of Spin-Crossover Polymer Plus Polyaniline Composites With Fe3O4 Nanoparticles, Esha Mishra, Waikiat Chin, Kayleigh A. Mcelveen, Thilini K. Ekanayaka, M. Zaid Zaz, Gauthami Viswan, Ruthi Zielinski, Alpha T. N'Diaye, David Shapiro, Rebecca Lai, Robert Streubel, Peter A. Dowben

Department of Chemistry: Faculty Publications

Adding Fe₃O₄ nanoparticles to composites of [Fe(Htrz)₂(trz)](BF₄) spin-crossover polymer and polyaniline (PANI) drives a phase separation of both and restores the molecular structure and cooperative effects of the spin-crossover polymer without compromising the increased conductivity gained through the addition of PANI. We observe an increased on-off ratio for the DC conductivity owing to an enlarged off state resistivity and a 20 times larger AC conductivity of the on state compared with DC values. The Fe₃O₄ nanoparticles, primarily confined to the [Fe(Htrz)₂(trz)](BF₄) phase, are ferromagnetically coupled to …

Rotation-Inversion Isomerization Of Tertiary Carbamates: Potential Energy Surface Analysis Of Multi-Paths Isomerization Using Boltzmann Statistics, Brian Jameson, Rainer Glaser

Chemistry Faculty Research & Creative Works

Potential energy surface (PES) analyses at the SMD[MP2/6–311++G(d,p)] level and higher-level energies up to MP4(fc,SDTQ) are reported for the fluorinated tertiary carbamate N-ethyl-N-(2,2,2-trifluoroethyl) methyl carbamate (VII) and its parent system N,N-dimethyl methyl carbamate (VI). Emphasis is placed on the analysis of the rotational barrier about the CN carbamate bond and its interplay with the hybridization of the N-lone pair (NLP). All rotational transition state (TS) structures were found by computation of 1D relaxed rotational profiles but only 2D PES scans revealed the rotation-inversion paths in a compelling fashion. We found four unique chiral minima of VII, one pair each of …

Rotation-Inversion Isomerization Of Tertiary Carbamates: Potential Energy Surface Analysis Of Multi-Paths Isomerization Using Boltzmann Statistics, Brian Jameson, Rainer Glaser

Chemistry Faculty Research & Creative Works

The front cover artwork is provided by Prof. Rainer Glaser's group at the Missouri University of Science and Technology. The image shows one of four potential energy surfaces generated from our rotation-inversion study of tertiary carbamates and highlights two of the eight possible transition state pathways between two ensembles of E- and Z-minima. In the context of synthetic studies of fluorinated carbamates R₁ O-CO-N(R₂ )CH₂ CF3, we unexpectedly observed two sets of ¹³C NMR quartets for the CF₃ group and we needed to understand their origin. Read the full text of the Research Article at …

Identification And Biosynthetic Study Of The Siderophore Lysochelin In The Biocontrol Agent Lysobacter Enzymogenes, Amanda Lynn Miller, Shanren Li, Catherine D. Eichhorn, Yongbiao Zheng, Liangcheng Du

Liangcheng Du Publications

Lysobacter is a genus of bacteria emerging as new biocontrol agents in agriculture. Although iron acquisition is essential for the bacteria, no siderophore has been identified from any Lysobacter. Here, we report the identification of the first siderophore, N1,N8-bis(2,3-dihydroxybenzoyl)spermidine (lysochelin), and its biosynthetic gene cluster from Lysobacter enzymogenes. Intriguingly, the deletion of the spermidine biosynthetic gene encoding arginine decarboxylase or SAM decarboxylase eliminated lysochelin and the antifungals, HSAF and its analogues, which are key to the disease control activity and to the survival of Lysobacter under oxidative stresses caused by excess iron. The production of …

Electromechanical Coupling In Collagen Measured Under Increasing Relative Humidity, Arwa Bazaid, Fengyuan Zhang, Qiancheng Zhang, Sabine Neumayer, Denise Denning, Stefan Habelitz, Ana Marina Ferreira, Brian J. Rodriguez

Articles

The functional role of collagen piezoelectricity has been under debate since the discovery of piezoelectricity in bone in 1957. The possibility that piezoelectricity plays a role in bone remodelling has generated interest in the investigation of this effect in relevant physiological conditions; however, there are conflicting reports as to whether collagen is piezoelectric in a humid environment. In macroscale measurements, the piezoelectricity in hydrated tendon has been shown to be insignificant compared to dehydrated tendon, whereas, at the nanoscale, the piezoelectric effect has been observed in both dry and wet bone using piezo response force microscopy (PFM). In this work, …

Architecture Of Heptagonal Metallo-Macrocycles Via Embedding Metal Nodes Into Its Rigid Backbone, A.M.Shashika D. Wijerathna, He Zhao, Qiangqiang Dong, Qixia Bai, Zhiyuan Jiang, Jie Yuan, Jun Wang, Mingzhao Chen, Markus Zirnheld, Rockwell T. Li, Yuan Zhang, Yiming Li, Pingshan Wang

College of Sciences Posters

Metal-organic macrocycles have received increasing attention not only due to their versatile applications such as molecular recognition, compounds encapsulation, anti-bacteria and others, but also for their important role in the study of structure-property relationship at nano scale. However, most of the constructions utilize benzene ring as the backbone, which restricts the ligand arm angle in the range of 60, 120 and 180 degrees. Thus, the topologies of most metallo-macrocycles are limited as triangles and hexagons, and explorations of using other backbones with large angles and the construction of metallo-macrocycles with more than six edges are very rare.

In this study, …

Phytochemical Screening, Chemical Composition And Antimicrobial Activities Of Ethanol, Methanol And Chloroform Extracts From The Leaves Of Digitaria Sanguinalis, Digitaria Ischaemum And The Bark Of Carapa Guianensis Found In Guyana, South America., Rajendra Kumar Khelawan

Theses and Dissertations

Chloroform, Ethanol and Methanol extracts of the leaves from DIGITARIA SANGUINALIS, DIGITARIA ISCHAEMUM and the bark from CARAPA GUIANENSIS found in Guyana were obtained via maceration and reflux extraction processes. Ethanol extracts obtained from the 25-minute reflux process produced the best percentage yield and the most thin layer chromatographic spots. All further analyses were conducted on the ethanol extracts of all plant materials. The ethanolic extracts showed positive phytochemical testing results for Terpenes, Flavonoids, Steroids, Tannins, Phenolic, Proteins, Cardiac Glycoside, Reducing Sugars, and Carbohydrates. Conversely, Saponins were absent in Smooth Crabgrass and Crabwood’s bark but present in Long Hairy Crabgrass. …

Synthesis And Characterization Of Mixed Ligand Complexes Of Ruthenium(Ii) Containing 2,2’-Bipyridine And 3,3’-Dimethyl-1,1’- Methylenebisimidazolium Ligands; A New Synthetic Approach, Matthew Schneider

Theses and Dissertations

Research into solar cells has been prioritized given the global demand for better renewable energy technologies. This demand is a result of the long-term use of fossil fuels, which generates significant pollution in highly populated urban areas. One potential solar cell technology is the dye-sensitized solar cell (DSSC). This kind of solar technology utilizes organometallic dyes to expand the types of wavelengths solar cells can use to generate electricity.12 Ruthenium(II) metal complexes of this type have been investigated heavily for this purpose.13,14,36 The main reasoning behind this is the metal-to-ligand charge-transfer (MLCT) phenomenon that such complexes exhibit. MLCT has often …

Design, Synthesis And Biological Evaluation Of A Novel Bioactive Indane Scaffold 2-(Diphenylmethylene)C-2,3-Dihydro-1h-Inden-1-One With Potential Anticancer Activity, Tao Zhang, Vilmar Bandero, Claire Corcoran, Ismael Obaidi, Manuel Ruether, John O'Brien, Lorraine O'Driscoll, Neil Frankish, Helen Sheridan

Articles

Over the past decades, designing of privileged structures has emerged as a useful approach to the discovery and optimisation of novel biologically active molecules, and many have been successfully exploited across and within different target families. Examples include indole, quinolone, isoquinoline, benzofuran and chromone, etc. In the current study, we focus on synthesising a novel hybrid scaffold constituting naturally occurring benzophenone (14) and indanone (22) ring systems, leading to a general structure of 2-(diphenylmethylene)-2,3-dihydro-1H-inden-1-one (23). It was hypothesised this new hybrid system would provide enhanced anti-cancer activity owing to the presence of the common features associated with the tubulin binding …

Development Of A Screening Methodology For The Analysis Of Rhodamine B In Foodstuffs, George T. Knecht

Honors Undergraduate Theses

Synthetic dyes that are used as color additives in foodstuffs are regulated by the Food and Drug Administration (FDA) under the Food, Drug, and Cosmetic Act (FD&C). The use of synthetic dyes not approved by the FDA, or the addition of dyes approved by the FDA above their maximum concentration limits in foodstuffs necessarily constitutes illegal food adulteration. Recently, rhodamine B (RhB), a bright-pink synthetic dye not approved for use in foodstuffs, has become an adulterant of interest due to its discovery in a large variety of food samples, and its identity as a potential carcinogen. Numerous chromatographic and spectroscopic …

Green Synthesis Of Nanoparticles And Their Utilization In Electrochemical Detection Of Catechol- Or Phenol-Based Substances, Daniel Laurence Myers Iii

Browse all Theses and Dissertations

PART A: GREEN SYNTHESIS OF COPPER NANOPARTICLES AND THEIR UTILIZATION IN THE DETECTION OF NEUROTRANSMITTERS Neurotransmitters, such as dopamine and epinephrine, are chemicals frequently found in the brain and are responsible for a number of human moods, needs, and emotions.1, 2 Detection of such neurotransmitters allows for a better judgement of a person’s physical and mental state, a utility that is vital in determining the presence of disease and mental illnesses.2 Electrochemical detectors used for such detections are often modified by materials such as metal nanoparticles.3 However, synthesizing nanoparticles can involve or produce chemicals, ammonium hydroxide among them, that are …

Molecular Organic Photovoltaic Cells And Applications, Julie Liu

Theses and Dissertations

The absorption, light scattering, and anti-Stoke’s fluorescence of chlorophyll and closely related sodium copper chlorophyllin were examined in various solutions with a wide range of refractive index and permittivity. It was evident that radiative photo electron decay corresponded to low permittivity solvents, but not to solvent refractive index. Additionally, non-radiative decay was dominant in high permittivity solvents. The properties suggest evolution has provided plants with an ability to redirect light to the chlorophyll in the high permittivity (water) photosynthesis center. Exploratory solar cells exploiting lifetime switching were developed and tested, wherein strong photovoltaic response was exhibited, along with the unique …

Mechanistic Insights Into Mftr-Dependent Regulation Of The Redox Cofactor Mycofactocin, Aigera Mendauletova

Electronic Theses and Dissertations

Organic redox cofactors are essential for life. While classic flavins and nicotinamides are widely distributed across all domains of life, nature has also evolved niche cofactors in subsets of life domains. For example, in Actinobacteria, coenzyme F420 is commonly used in place of flavin mononucleotide in enzymes associated with carbon fixation and oxidation of secondary alcohols. The importance of niche cofactors has long been recognized however, detailed understanding about their biosynthesis and physiological uses has been lagging. One class of niche cofactors is derived from ribosomally synthesized and posttranslationally modified peptides (RiPPs). To achieve their mature form, the genetically …

Temperature Dependency Of Ion Channel Opennings, Loren Haarsma, Sebastian Grabill, Dylan Mount

Summer Research

Alamethicin is a 20 amino-acid peptide produced by fungus. When added to a lipid bilayer they self-assemble into voltage-dependent ion channels which open for brief periods called dwell times, usually on order of a few milliseconds. See poster by Dylan Mount regarding electrical properties of lipid bilayers without Ion channels. Our goal is to measure the electrical current through a single Alamethicin ion channel as it opens and closes and see how its gating behavior is affected by lipid temperature and lipid composition. Since lipid bilayers and ion channels are critical for almost all living cells, studying them can prove …

The Photophysical Properties Of Fluorescent Coumarins, Mark Muyskens, Mariana Dykstra

Summer Research

Coumarins are organic molecules that can be found in nature and act like bioactives. Their fluorescent properties were found to change significantly with alterations in substituents in their structure.

Enhancement Of Metal Nanostructure Deposition On Silicon Laser-Induced Periodic Surface Structures By Galvanic Replacement, Nicholas Simpson, Eric J. Broadhead, Addison Casto, Katharine M. Tibbetts

Chemistry Publications

We report a chemically motivated, single-step method to enhance metal deposition onto silicon laser-induced periodic surface structures (LIPSSs) using reactive laser ablation in liquid (RLAL). Galvanic replacement (GR) reactions were used in conjunction with RLAL (GR-RLAL) to promote the deposition of Au and Cu nanostructures onto a Si LIPSS. To increase the deposition of Au, sacrificial metals Cu, Fe, and Zn were used; Fe and Zn also enhanced the deposition of Cu. We show that the deposited metal content, surface morphology, and metal crystallite size can be tuned based on the difference in electrochemical potentials of the deposited and sacrificial …

The Effect Of S-Glutahionylation Of Keap-1/Nrf-2 And Caspase 3, Claire Greenless

Celebration of Scholarship 2023

S-glutathionylation is a form of post-translational modification where glutathione forms disulfide bonds with protein cysteine residues under oxidative conditions. The process of Sglutathionylation is important because it is a reversible process, regulates enzyme activity, and may link to disease development. In this work, under physiological conditions, KEAP-1 and NRF-2 bind together as a complex. Upon oxidative stress, NRF-2 dissociates from KEAP-1 and triggers an antioxidant response. However, the dissociation mechanism was not well studied. S-glutathionylation of KEAP-1 causes dissociation of NRF-2. This result demonstrates a possible dissociation mechanism of NRF-2. Caspase 3 is a cysteine containing protein and a key …

Modification Of Hyaluronic Acid To Enable Click Chemistry Photo-Crosslinking Of Hydrogels With Tailorable Degradation Profiles, Ciara Buckley

Articles

Hyaluronic acid (HA) is a naturally occurring mucopolysaccharide that, due to its inherent bioactivity and extracellular matrix-like structure, has the potential to be utilised extensively in tissue engineering. However, this glycosaminoglycan lacks the properties required for cellular adhesion and photo-crosslinking by UV light, which significantly hinders this polymers applicability. This research presents a method for modifying hyaluronic acid via thiolation and methacrylation to generate a novel photo-crosslinkable polymer with improved physicochemical properties, biocompatibility and the potential to customize biodegradability according to the ratio of monomers used. A decrease in stiffness proportional to increasing thiol concentration was observed when testing the …

How Pulse Width Affects Laser Ablation Of Organic Liquids, Laysa M. Frias Batista, Ella Kaplan, Chamari Weththasingha, Benjamin Cook, Samuel Harris, Ashish B. Nag, Katharine M. Tibbetts

Chemistry Publications

Laser synthesis in liquids is often carried out in organic solvents to prevent oxidation of metals during nanoparticle generation and to produce tailored carbon-based nanomaterials. This work investigates laser ablation of neat organic liquids acetone, ethanol, n-hexane, and toluene with pulse widths ranging from 30 fs to 4 ps through measurements of reaction kinetics and characterization of the ablation products with optical spectroscopy and mass spectrometry. Increasing the pulse width from 30 fs to 4 ps impacts both the reaction kinetics and product distributions, suppressing the formation of solvent molecule dimers and oxidized molecules while enhancing the yields of …

Post-Translational Modification Of Proteins Via Ambient Air Pollutants And Endogenous Reactive Species, Rachel Lauren Davey

Electronic Theses and Dissertations

Proteins can react with reactive oxygen species (ROS) and reactive nitrogen species (RNS) to form post-translational modifications (PTMs), which can affect protein structure and function. The formation of 3-nitrotyrosine (NTyr) and dityrosine (DiTyr) upon reaction of proteins with ROS/RNS are two common PTMs studied due to their stability and irreversibility, as well as their ability to enhance the allergenicity of pollen allergens upon formation. Many common techniques used to study the formation of these PTMs can reliably detect the PTMs but can only provide semi-quantitative information due to many assumptions and limitations. In Chapter 2 we present an analysis of …

Glutathione And Glutaredoxin—Key Players In Cellular Redox Homeostasis And Signaling, Yuh-Cherng Chai, John J. Mieyal

2023 Faculty Bibliography

This Special Issue of Antioxidants on Glutathione (GSH) and Glutaredoxin (Grx) was designed to collect review articles and original research studies focused on advancing the current understanding of the roles of the GSH/Grx system in cellular homeostasis and disease processes. The tripeptide glutathione (GSH) is the most abundant non-enzymatic antioxidant/nucleophilic molecule in cells. In addition to various metabolic reactions involving GSH and its oxidized counterpart GSSG, oxidative post-translational modification (PTM) of proteins has been a focal point of keen interest in the redox field over the last few decades. In particular, the S-glutathionylation of proteins (protein-SSG formation), i.e., mixed disulfides …

Trichloroethylene (Tce) Metabolite S-(1,2-Dichlorovinyl)-L-Cysteine (Dcvc) Inhibits Lps-Stimulated Cxcl-2 Production In Thp-1 Cells, Karena Moleakunnel, Audrey Luce, Lyric Johnson, Erica Boldenow, Sean Harris

Summer Research

• TCE is a volatile industrial solvent commonly found in the environment is known to be a "human carcinogen". However, its effects on gestational tissues and inflammatory pathways remain unknown. 1
• TCE inhibits various cytokines like IL-1b, IL-6, IL-8, and TNF-a.
• CXCL2 is a cytokine involved in the recruitment of neutrophils which serve as a key immune defense against infection. 3
• In past research, mice with the reduction of CXCL-2 showed reduced survival rates.
• Goal:• Analyze CXCL-2 production in THP-1 cells treated with DCVC • Understand how DCVC affects the cytokine pathway

Measuring Monoglyceride Densities Via Pycnometry, Lucas Postuma, Paul Harper

Summer Research

Glycerides are a type of lipid, and are comprised of a hydrophilic head group and one or more hydrophobic tail groups. Monoglycerides have glycerol head group, and one fatty acid chain as a tail group (Fig 1). They form interesting and complex structures/phases at different temperatures (Fig 2). Monoglycerides have many applications in drug delivery, protein crystallization scaffolds, and nanoscale templates (Seper et al). However, even though they are so ubiquitous, the measurements we have of monoglycerides such as monoolein are sparse in the literature, and the data that exist are contradictory; there is a need for systematic density measurements. …

Computational Modelling Of Cys-Tyr Containing Proteins, Alina Sainju, David Benson

Summer Research

Mammalian cysteine dioxygenase (CDO) is a non-heme iron enzyme that is known for catalyzing the conversion of cysteine (Cys) to Cysteine sulfinic acid (CSA) in the body. Cysteine is an essential amino acid needed in the body but if cysteine levels are not regulated and it gets too high then it can become toxic for the body. For this reason, CDO starts cysteine degradation and, therefore, CDO is important for cysteine level regulation. While it is known that CDO aids in cysteine regulation, the exact pathway mechanism of how it does so is still unclear. It is hypothesized that loss-of-function …

Use Of Inner/Outer Sphere Terminology In Electrochemistry—A Hexacyanoferrate Ii/Iii Case Study, John Cassidy, Rafaela Cristina De Carvalho, Tony Betts

Articles

Salts of hexacyanoferrate II/III anions have been widely used as redox couple probe molecules to determine the characteristics of electrode surfaces. Examples include the assessment of electrocatalysts for energy applications and electrocatalysts for the detection of biological or chemical species, as well as the determination of electrochemically active surface areas. An examination of the electrochemical literature, based largely on cyclic voltammetric investigations, reveals a wide range of peak separation and/or heterogeneous electron transfer rate constants, classified sometimes as inner or outer sphere electron transfer processes. Originally developed for the mechanistic interpretation of inorganic transition metal compounds in solution, this terminology …

Avidin Cooperative Allosterism Upon Binding Biotin Observed By Differential Changes In Intrinsic Fluorescence, Mark J. Waner, Gianna Ellis, Meghan Graeca, Nicholas Ieraci, Cole Morell, Alycia Murphy, David P. Mascotti

2023 Faculty Bibliography

Similar to streptavidin, the binding of biotin by avidin does not appear to be cooperative in the traditional sense of altered binding strength, though it appears to be cooperative in terms of ligand induced structural communication across subunits in the protein as previously shown for streptavidin. In this work we provide data from intrinsic tryptophan fluorescence as evidence of a cooperative structural change. The technique involves examination of the changes in fluorescence emission corresponding to the various tryptophan populations accompanying avidin-biotin binding. We note that the 335 nm emission population (i.e. more hydrophobic local environment) saturates prior to full ligation …

Determined Mechanism For The Formation Of 2-Bromo-3-Methylbutane, Gabriele Cross

Senior Honors Projects

Carbocation rearrangements are particularly interesting mechanistic steps in organic reactions. Carbocations form when a carbon atom within a molecule is electron deficient, giving it a positive charge. A rearrangement occurs when either a hydrogen atom or methyl group from an adjacent carbon atom in the molecule moves to the carbocation, thus moving the carbocation to the adjacent carbon. This rearrangement only occurs if the newly formed carbocation is more stable than the previous carbocation. These concepts are typically taught in organic chemistry courses. Researchers from Villanova University, the University of Wisconsin-River Falls, and Bethel University designed an experiment to help …

Novel Application Of Graphene Oxide In Conjunction With Dna Binding Dcas9 For Detecting Antibiotic Resistance Genes, Langley Williams

Mahurin Honors College Capstone Experience/Thesis Projects

The frequent emergence of antibiotic resistance genes poses a stumbling block to prompt treatment of pathogen-originating diseases and therefore spurs the demand for a simple, rapid diagnostic device that can outcompete the time and cost of traditional methods such as PCR and cell culturing. The proposed method for detecting pathogenic DNA utilizes the binding properties of deactivated CRISPR-associated protein9 (dCas9) complexed with fluorescein-labeled single-guide RNA (sgRNA) and the fluorescence quenching properties previously demonstrated in graphene oxide (GO). For our assay, we designed sgRNAs to target specific 20 nucleotide sequences extracted from the tetracycline resistance (tetM) gene sequence and covalently modified …

Synthesis Of Cysteine-Tyrosine Crosslinks In Β-Hairpin Peptide Models, C.D. Tatko, David Benson, Sophie A. Hruska

Summer Research

The Cysteine-Tyrosine crosslink (Cys-Tyr) is - A unique Post-Translational Modification - Redox-active - Found in a handful of proteins, including Cysteine Deoxygenase (CDO), whose malfunction has been linked to Alzheimer’s Disease

In Vitro Corrosion And Biocompatibility Behavior Of Cocrmo Alloy Manufactured By Laser Powder Bed Fusion Parallel And Perpendicular To The Build Direction, Masoud Atapour, Saber Sanaei, Zheng Wei, Mohammadali Sheikholeslam, Jeffrey D. Henderson, Ubong Eduok, Yara K. Hosein, David W. Holdsworth, Yolanda S. Hedberg, Hamid Reza Ghorbani

Chemistry Publications

Biomedical cobalt-chromium-molybdenum alloys (CoCrMo) are frequently used for orthopedic implant and dental materials exposed to mechanical stressors, such as wear and cyclic load. Due to the high demand for customizable implant shapes, these alloys are increasingly manufactured by additive manufacturing methods such as laser powder bed fusion (LPBF). LPBF results in different microstructures and surface roughness as a function of the building direction. This study investigated the corrosion resistance, bioactivity, biocompatibility, and microstructure of LPBF CoCrMo (low carbon content, heat-treated) in the XY (perpendicular) and XZ (parallel) plane of the building direction for as-printed (as-received) and abraded surfaces. A distinct …