Analytical Chemistry Commons^™

Isolation, Structure Elucidation, And Synthesis Of Natural Products From Marine Cyanobacteria, Keren Solomon

Electronic Theses and Dissertations

This thesis describes the isolation, structure elucidation, and synthesis of natural products from marine cyanobacteria. A crude extract from a cyanobacterium collected in Curacao showed selective affinity for the dopamine D₅ receptor in a screen against a panel of CNS receptors. Due to the high similarity of the D₅ and D₁ receptor, to date there are no known ligands that differentiate them. Attempts to purify the compound responsible for this affinity led to the isolation of the known compound caylobolide A. A second extract from a cyanobacterium collected in Panama underwent bioassay-guided fractionation and yielded the novel …

Electrostatic Denaturation Of Dna-Cisplatin Adducts, Eddie Madrigal

Master's Theses

In this thesis, electrochemical approaches are used to determine the properties of deoxyribonucleic acid (DNA) by electrostatic denaturation. The electrochemical routine involves an application of a destabilization potential, an equilibration potential, and a square wave voltammogram (SWV) to monitor the extent of melting. Our method uses a monolayer consisting of thiol modified DNA and mercaptohexanol on a gold electrode. These electrodes are then incubated in a complementary sequence tagged with methylene blue. By using our electrostatic denaturation technique, different parameters are explored, such as surface densities, surface coverages, and ionic strengths. As proof of concept, these techniques were applied toward …

Structural Characterization Of Organic Matter In Oil Shales Using Multiple Nuclear Magnetic Resonance Spectroscopic Techniques, Wenying Chu

Chemistry & Biochemistry Theses & Dissertations

Oil shale is a promising source of hydrocarbon fuel that is distributed throughout the world. The petroleum generating potential of oil shale is related to the molecular structure of the organic matter in source rock. The major fraction of organic matter of oil shale is termed kerogen, and due to its insolubility in organic solvents, ¹³C solid-state nuclear magnetic resonance (NMR) spectroscopy is one of the best ways to directly measure the insoluble organic matter without changing its chemical structures. This dissertation investigated oil shale samples using advanced solid-state ¹³C NMR spectroscopy techniques and high resolution magic angle …

Application Of Carbon Nanoparticles As Dna Detection Probe And Fluorescent Ink, Luckio Frank Owuocha

Graduate Theses/Dissertations

There is a significant interest in developing a sensitive, selective, efficient, and inexpensive method for rapid molecular diagnostic tests. This research aims to develop an inexpensive nucleic acid detection method by using DNA-conjugated carbon nanoparticles that exhibit fluorescence in the visible region. Carbon nanoparticles of this class can be detected without specialized equipment and have great promise toward the development of analytical methods that can be used in resource-limited environments with a lack of access to proper diagnostic and healthcare. We employed EDC-NHS (two-step) and EDC (one-step) coupling techniques to prepare DNA-conjugated carbon nanoparticles. The dot blotting method was adapted …

A Simple Predictive Model For Estimating Relative E-Cigarette Toxic Carbonyl Levels, Shawna Vreeke, Xijing Zhu, Robert Strongin

Chemistry Faculty Publications and Presentations

E-cigarette devices are wide ranging, leading to significant differences in levels of toxic carbonyls in their respective aerosols. Power can be a useful method in predicting relative toxin concentrations within the same device, but does not correlate well to inter-device levels. Herein, we have developed a simple mathematical model utilizing parameters of an e-cigarette’s coil and wick in order to predict relative levels of e-liquid solvent degradation. Model 1, which is coil length/(wick surface area*wraps), performed in the moderate-to-substantial range as a predictive tool (R² = 0.69). Twelve devices, spanning a range of coil and wick styles, were analyzed. …

Toward Development Of A Paper-Based Microanalytical Device For Heavy Metal Ion Detection By Enzyme Inhibition, Adjoa Otubea Adams

Graduate Theses/Dissertations

In recent years, paper-based microanalytical devices have attracted great attention in broad application areas including the colorimetric detection of heavy metal ions. The simplicity, portability, and low cost of the devices offer unique advantages over conventional instrumental analysis. This project utilizes the inhibition of an enzyme-catalyzed reaction by metal ions to develop a paper-based analytical device for the detection of heavy metal contaminants such as mercury. I selected alkaline phosphatase for this study. This enzyme possesses Mg and Zn ions in its active site. Therefore, the competitive displacement of these metal ions and/or denaturation of the enzyme by heavy metal …

Visualization Without Vision – How Blind And Visually Impaired Students And Researchers Engage With Molecular Structures, Croix J. Laconsay, Henry B. Wedler, Dean J. Tantillo

Journal of Science Education for Students with Disabilities

This article examines the tools and techniques currently available that enable blind and visually impaired (BVI) individuals to visualize three-dimensional objects used in learning chemistry concepts. How BVI individuals engage with and visualize molecular structure is discussed and recent tactile (or haptic) and auditory methods for visualization of various chemistry concepts are summarized. Remaining challenges for chemistry education researchers are described with the aim of highlighting the potential value of educational research in further enabling BVI students to pursue careers in science, technology, engineering, and mathematics (STEM) fields.

The Recreation Of Wound Patterns Using Various Tissue Simulants For Crime Scene Reconstruction, Breanne Steimle

Forensic Science Master's Projects

Within the field of forensic science, there are limited reliable methods for the simulation of pattern injuries on human skin and tissue that may aid in aspects of crime scene reconstruction. The tissue simulant must be of sufficient integrity for recording blunt force trauma and bite mark impressions, electrocution, cutting, and gunshot wound related injuries for the purpose of re-enactment, court exhibition, and distance determination. For wound reenactments (such as blunt force trauma, bite mark impressions and electrocution), dead skin and tissue from human cadavers do not show wounding patterns that would occur on live tissue. This study examines different …

Nitrogen-Doped Graphene-Based Metal Composites For The Non-Enzymatic Detection Of Hydrogen Peroxide, Tajabadi Poor Mohammad Taghi

Student Works (2020-2029)

Recently, much attention has been devoted to detecting hydrogen peroxide (H2O2) because of its extensive range of applications in chemical synthesis, the textile industry, food production, fuel cell devices, and even in many oxidative biological reactions. Among the various methods of detection of H2O2, electrochemical sensors has many advantages, such as simplicity, high efficiency and sensitivity, as well as good selectivity., To improve the sensitivity of non-enzymatic sensors, noble metal nanoparticles with particular electrocatalytic activities can be utilized. The present research is aimed to design a hybrid approach for the development of novel nanostructures for non-enzymatic detection of H2O2. Herein, …

Graphene Oxide Gold Nanostructure Based Surface Enhanced Raman Scattering Dna Biosensor For The Detection Of Meat Species, Khalil Md. Ibrahim

Student Works (2020-2029)

Authentication, detection and quantification of the ingredients, and adulterant in the food, meat and meat products are of high importance in current days. However, the conventional meat species detection techniques based on lipid, protein and DNA biomarkers have been confronting challenges due to the poor selectivity, sensitivity, and unsuitability for processed food products or complex food matrices. Hence, nanoparticle based DNA biosensing strategies have attracted the most interests and considered as one of the best alternatives to conventional strategies. Among these, surface enhanced Raman scattering (SERS) has gained the substantial acceptance as an excellent, fast and ultrasensitive sensing technique due …

Three-Event Energy Detection With Adaptive Threshold For Spectrum Sensing In Cognitive Radio Systems, Alexandru Martian, Mahmood Jalal Ahmad Al Sammarraie, Calin Vladeanu, Dimitrie Popescu

Electrical & Computer Engineering Faculty Publications

Implementation of dynamic spectrum access (DSA) in cognitive radio (CR) systems requires the unlicensed secondary users (SU) to implement spectrum sensing to monitor the activity of the licensed primary users (PU). Energy detection (ED) is one of the most widely used methods for spectrum sensing in CR systems, and in this paper we present a novel ED algorithm with an adaptive sensing threshold. The three-event ED (3EED) algorithm for spectrum sensing is considered for which an accurate approximation of the optimal decision threshold that minimizes the decision error probability (DEP) is found using Newton’s method with forced convergence in one …

Thiophene Derivative Monomers Co-Electropolymerized On Microelectrodes Within Arrays For Tailored Surface Chemistry And Electrochemical Properties, Benjamin J. Jones

Graduate Theses and Dissertations

Potentiodynamic co-electropolymerization of two thiophene derivatives, (2,3-dihydrothieno[3,4-b]dioxin-2-yl)methanol (1) and 4-((2,3-dihydrothieno[3,4-b][1,4]dioxin-2-yl)-methoxy)-4-oxobutanoic acid (2), in aqueous solutions (0.02 M total monomer, 0.05 M sodium dodecyl sulfate (SDS) and 0.1 M LiClO4) on gold microband electrodes in an array was investigated. A modified Steglich esterification reaction between monomer 1 and succinic anhydride produced monomer 2 at 93.6% yield. Seven deposition solutions of the two monomers, defined by mol% of monomer 2 (0, 25, 34, 50, 66, 75, 100) generated seven sets of polymer films by cyclic voltammetry in a specially designed cell to conserve monomer. The onset potential for monomer oxidation and total …

Synthesis And Raman Study Of Hollow Core-Shell Ni1.2Co0.8P@N-C As An Anode Material For Sodium-Ion Batteries, Jia-Hui Chen, Xiao-Bin Zhong, Chao He, Xiao-Xiao Wang, Qing-Chi Xu, Jian-Feng Li

Journal of Electrochemistry

With the increasing demand for large-scale energy storage, great progress has been made in discovering new advanced energy storage materials. Sodium-ion batteries (SIBs) have attracted much attention in recent years due to their use of abundant sodium resources and their comparable electrochemical capacity to lithium-ion batteries (LIBs). In this paper, we developed novel hollow core-shell Ni-Co bimetallic phosphide nanocubes with N-doped carbon coatings (Ni_1.2Co_0.8P@N-C) as the anode material for SIBs. The material was synthesized through a low-temperature phosphorization method using resorcinol formaldehyde (RF) resin coating with a Ni-Co Prussian blue analogue (PBA) as a template and …

Antimicrobial Strategies For Topical Applications, Kelsey Marie Lopez

LSU Doctoral Dissertations

Bacteria can thrive in diverse environments and are often harmless or beneficial. Bacteria in digestive tracts is one example of beneficial bacteria; however, bacteria can be harmful and when this type proliferates, it can cause infections within hosts. Bacterial infections are easily treated with antibiotics in most cases. However, bacteria are also capable of developing mutations which could cause them to become multi-drug resistant and eventually, “superbugs.” Therefore, the development of novel antimicrobial agents and materials capable of combating drug-resistant bacteria is necessary. Research presented in this dissertation focuses on different strategies for minimizing and preventing topical bacterial infections using …

Adsorption Behavior Of Chemically / Charged Modified Antibodies On Gold Nanoparticles, Samuel Okyem

Theses and Dissertations

Gold nanoparticles (AuNPs) have been exploited in the various domains of science such as drug delivery, bio-sensing, immunoassays and environmental sensors, due to their optical properties and intriguing surface chemistry. Different scientific procedures have been used to effectively immobilize antibodies onto AuNPs. Although acceptable outcomes have been achieved in the immobilization of antibodies onto AuNPs, the sensitivity of these immobilized antibodies to target antigen or binding sites is limited due to improper orientation of the antibodies. Also, the possibility of nanoparticle aggregation when exposed to proteins limits its biomedical applicability.

There is some evidence that the surface charge of antibodies …

Ordered Mesoporous Carbon/Graphene/Nickel Foam For Flexible Dopamine Detection With Ultrahigh Sensitivity And Selectivity, Lai-Yu Wang, Xin Xi, Dong-Qing Wu, Xiong-Yu Liu, Wei Ji, Rui-Li Liu

Journal of Electrochemistry

Electro-catalytic reduction is an efficient way to achieve resourcable transformation of CO₂, which is one of the important techniques to solve the global environmental problems originated from excessive CO₂ emission. In this study, a membrane electrode assembly(MEA) type CO₂ electro-reduction electrolytic cell was constucted, which enables CO₂ feeding and real-time KHCO₃ aqueous updating on both sides of the cathode gas diffusion electrode (GDE). By means of the electrolytic cell, effects of KHCO₃ concentration and updating inside the liquid electrolytic chamber on CO₂ electro-reduction activity, production distribution and stability were investigated. The experimental …

A Simple And Sensitive Aptamer-Based Electrochmical Sensor For Determination Of Aflatoxin B1, Bing Liu, Yao-Shuai Zhao, Yue Qin, Yi Wang, Yan-Jie Zhu, Shuo Wang

Journal of Electrochemistry

Aflatoxin B1 has attracted much attention because of its high toxicity and carcinogenicity, which has become a great concern in food safety. Based on the principle of specific binding between Aflatoxin B1 and its aptamer, an aptamer-based electrochemical sensor had been designed and developed for the determination of minor Aflatoxin B1 contained in grain. The mesoporous carbons were first modified on the surface of the working electrode, and then the gold nanoparticles were on-site electrodeposited at a constant potential. Each modified electrode was characteritised by scanning electron microscopy (SEM) and electrochemical impedance spectroscopy (EIS). As a result, the surface area …

Pyrene Pyrimidine Derivatives: Synthesis, Characterization And Applications, John Kihara Mathaga

LSU Master's Theses

In this thesis, development of new materials to the field of optoelectronics were studied. Optoelectronic devices based on organic semiconductors in order to replace their inorganic counterparts have been an increasing focus of research in recent decades. Organic light-emitting diodes (OLEDs) have gained commercial acceptance for their potential use in high-resolution displays and solid-state lighting. This general acceptance is despite the fact that organic electronic concepts (solar cells, transistors and detectors) are still in an early stage of development. OLEDs materials intrinsic advantages, like low power consumption as compared to LED counterparts, a tunable color range, ease of manufacturing, and …

Synthesis, Characterization, And Investigation Of Metal Ion Quenching In Fluorescent Carbon Dot Surrogates For Particulate Matter Black Carbon And Evaluation Of Cellular Health Effects Due To The Surrogate Materials, Christopher Lee Sumner Jr

LSU Doctoral Dissertations

Black carbon (BC) is an environmental pollutant of particular concern to many international organizations for both its health effects and environmental effects. Probing health effects of BC as produced in the environment is difficult due to the complex nature of environmental pollutants found in their naturally occurring state. Fluorescent carbon dots (FCDs) were chosen to be used as a surrogate for BC. In the process of examining FCDs and their behavior as surrogates, information was gained on the health effects and behavior of FCDs as a class of nanomaterials for cell and tissue studies, which is outlined in this dissertation. …

Effect Of Post-Consumer Content And Bioplastic Incorporation On Polymeric Resin In Consumer Applications, Shelby Bicknell

Electronic Theses & Dissertations

Controversy surrounds the use of plastic products, primarily due to their potentially negative impact on the environment at the end of their lifecycle. The most widely used plastics are manufactured from petrochemicals such as petroleum, coal or natural gas. Petrochemical plastics are not able to readily breakdown in the environment, which aggravates the existing pollution problems. Fortunately, there are eco-friendly alternatives to petrochemical-based plastics. Bioplastics may be derived from renewable sources, biodegradable, or both. Bio-based plastics are plastics that may be derived from renewable biomass sources including, but not limited to, vegetable oils, cornstarch, straw, woodchips, and food waste. They …

Fabrication Of Polymer Monoliths Within The Confines Of Non-Transparent 3d-Printed Polymer Housings, Noor Abdulhussain, Suhas H. Nawada, Sinéad Currivan, Marta Passamonti, Peter J. Schoenmakers

Articles

In the last decade, 3D-printing has emerged as a promising enabling technology in the field of analytical chemistry. Fused-deposition modelling (FDM) is a popular, low-cost and widely accessible technique. In this study, RPLC separations are achieved by in-situ fabrication of porous polymer monoliths, directly within the 3D-printed channels. Thermal polymerization was employed for the fabrication of monolithic columns in optically non-transparent column housings, 3D-printed using two different polypropylene materials. Both acrylate-based and polystyrene-based monoliths were created. Two approaches were used for monolith fabrication, viz. (i) in standard polypropylene (PP) a two-step process was developed, with a radical initiated wall-modification step …

The Synthesis Of A Mepeg-Based Hydroxide Conducting Electrolyte And The Optimization Of The Mepeg-Tosylation Reaction, Andrew Ladner

Honors Theses

As society is becoming increasingly aware of the effects of climate change and the ever-looming threat of a fuel shortage, exploring green and renewable alternative energy production, such as fuel cells, is paramount. This project investigates the synthesis of a polyethylene glycol monomethyl ether (MePEG_n) based polymer as well as the optimization of the MePEG Tosylation reaction. The MePEG explored contains seven polymerized ethoxy groups (MePEG₇). The MePEG₇ polymer was modified by substituting a positively-charged trimethylamine group in the place of the alcohol functional group at the end of the PEG chain. The reason for …

Intrinsic Buffer Hydroxyl Radical Dosimetry For Hydroxyl Radical Protein Footprinting, Addison Roush

Honors Theses

Hydroxyl radical protein footprinting (HRPF) coupled to mass spectrometry is a powerful technique for the analysis of protein topography as it generates covalent mass labels that can survive downstream sample handling, and it is sensitive to the solvent accessibility of amino acid sidechains. Of the multiple platforms for HRPF, fast photochemical oxidation of proteins (FPOP) utilizes a pulsed 248 nm KrF excimer laser to label proteins by photolyzing hydrogen peroxide. FPOP is the most widely used HRPF platform because it labels proteins faster than unfolding can occur. Variations in FPOP sample conditions make it difficult to compare results between experiments …

Investigation Of The History Of Fingerprinting, Advancements In The Field, And Development Of Potential Methods That Could Improve The Detection Of Endogenous And Exogenous Drugs In Latent Prints, Kristen Malloy

Honors Theses

When someone thinks of fingerprinting, they are most likely going to picture how a latent print is matched to the fingerprint of a suspect based on ridge pattern analysis. However, there is much more information that can be obtained from a latent print. The work performed in this thesis focuses the detection of exogenous and endogenous drugs in latent prints. The experiments performed analyzed fingerprints from volunteers that were contaminated with one of three common painkillers: acetaminophen, acetylsalicylic acid (ASA), and ibuprofen. Three different instruments were tested for this purpose: MALDI-MS, ATR-FTIR, and LC-MS. Based on the results gathered, it …

Comparison Of The Vibrational Modes Of Thiolated Gold Nanoparticles Undergoing Core-Conversions Via Raman Spectroscopy, William Gregory Cannella Jr.

Honors Theses

In this project, the vibrational characteristics/vibrational modes are explored via Raman Spectroscopy for thiolated-gold nanoparticles. This class of compounds is also known as gold nanoparticles (AuNPs). They remain of great interest in research areas such as catalysis, gold dependent nanoelectronics, drug delivery, and sensing, due to their unique size-dependent optical, chiroptical, and electronic properties. Vibrational spectroscopy of thiolated gold nanoparticles are oftentimes considered nontrivial as the compounds strongly absorb light in the visible region of the electromagnetic spectrum, are generally considered weak scatterers, and give off large amounts of fluorescence. This combined with their black appearance, susceptibility to localized heating, …

Glucose Oxidase And Prussian Blue Nanoparticles Encapsulated Within A Xerogel For Electrochemical Detection Of Glucose, Daniel Baker

Honors Theses

Recent literature reports examples of electrochemical biosensor systems based on the encapsulation of enzymes and metal nanoparticles into a xerogel for the detection of biologically important compounds, such as glucose. While these systems are very successful with acceptable detection limits and linear ranges. However, Prussian Blue modified electrodes have been shown to be better than metal electrodes for the detection of hydrogen peroxide. Here, a biosensor system where a xerogel in formed with both glucose oxidase and Prussian Blue nanoparticles.

Using Tandem Mass Spectrometry And Irmpd Spectroscopy To Determine The Intrinsic Reactions Of Uranyl-Containing Ions, Irena Tatosian

Electronic Theses and Dissertations

Developing a comprehensive understanding of the intrinsic reactivity of uranium-containing species remains an important goal, as it may influence future developments in areas ranging from new approaches to nuclear fuel processing to studies of the migration and fate of the element in the environment. At a more fundamental level, such studies contribute to the understanding of the role that 5-f electrons may play in chemical bonding, the so called “f-electron challenge”. Electrospray ionization (ESI) is an effective way to generate gas-phase complexes containing uranium and uranyl ions for subsequent studies of intrinsic structure and reactivity. Studies in the gas-phase are …

N-Terminal Imine Derivatization For Enhanced De Novo Peptide Sequencing: A Study Of The Fragmentation Pattern Generated From Cid Of Peptide-Imines, Khiry L. Patterson

Electronic Theses and Dissertations

In this work, the fragmentation pattern derived from model peptides derivatized to create N-terminal imines (Schiff bases) were evaluated. Collision-induced dissociation of the protonated peptide-imines ([M+H]⁺) generally produced complete series of the sequence informative a_n and b_n ions, now undoubtedly characteristic of the peptide ion species. A novel product ion was also observed, denoted the y^ǂ ion, determined by IRMPD spectroscopy and density functional theory to be generated from the elimination of the N-terminal amino acid residue despite the N-terminal modification. It was concluded the pathway involved a nucleophilic attack by an amide nitrogen and …

Heteroatom-Doped Chemical Vapor Deposition Carbon Ultramicroelectrodes, Alexis Sanwick

Undergraduate Honors Theses

Metal nanoparticles have been a primary focus in areas of catalysis and electrocatalysis applications as a result of their large surface area-to-volume ratios. While there is an increased interest in understanding the properties and behaviors of metal nanoparticles, they can become expensive over time. Recent research has incorporated the idea of using heteroatom-doped materials as a cheaper catalytic alternative to metal nanoparticles. In this study nitrogen-doping and phosphorous-doping techniques were applied to chemical vapor-deposited carbon ultramicroelectrodes in order to study the electrocatalytic properties toward the oxygen reduction reaction and the enhanced affinity for the deposition of gold nanoparticles onto the …

Gold Nanoparticles: Core Conversion Of Au144(Sch2ch2ph)60 To Au99(Sph-Ch3)42 Using Aromatic Thiolate Ligands And Crystallization Of Au99(Sph-Ch3)42, Elizabeth Turnage

Honors Theses

The purpose of this thesis is to synthesize Au₁₄₄(SCH₂CH₂Ph)₆₀ using a two-step synthesis reaction, and then using this product to conduct a core conversion from Au₁₄₄(SCH₂CH₂Ph)₆₀ to Au₉₉(SPh-CH₃)₄₂. The Au₉₉(SPh-CH₃)₄₂ product will then be used to attempt to form crystals using five different crystal set-up methods. Au₁₄₄(SCH₂CH₂Ph)₆₀ is made with aliphatic thiolate ligands, and when it is placed in a mixture containing excess para-methyl benzenethiol, it undergoes a …