Analytical Chemistry Commons^™

An Electrochemical Immunoassay System For Measuring Circulating Protein Biomarkers Of Pediatric Soft Tissue Sarcoma, Ivy Antwi

Electronic Theses and Dissertations

Measurement of circulating protein biomarkers associated with disease can facilitate early detection, help guide treatment strategies and improve patient outcomes beyond current standards of care. The combination of inexpensive 3D-printed flow cells and electrochemical biosensors has recently emerged as a viable platform for low-cost, reliable biomarker measurements. Here, we report an electrochemical immunoassay system based on simple graphite electrode arrays, 3D-printed flow cells, and signal-generating magnetic bead bioconjugates for simultaneous detection of three biomarker proteins (cancer antigen 125 (CA-125), midkine (MK) and osteopontin (OPN)) associated with pediatric soft tissue sarcomas (PSTS). Magnetic bead bioconjugates are functionalized with large amounts of …

Biomaterials With Structural Hierarchy And Controlled 3d Nanotopography Guide Endogenous Bone Regeneration, Shixuan Chen, Hongjun Wang, Valerio Luca Mainardi, Giuseppe Talò, Alec Mccarthy, Johnson V. John, Matthew J. Teusink, Liu Hong, Jingwei Xie

Department of Chemistry: Faculty Publications

Biomaterials without exogenous cells or therapeutic agents often fail to achieve rapid endogenous bone regeneration with high quality. Here, we reported a class of three-dimensional (3D) nanofiber scaffolds with hierarchical structure and controlled alignment for effective endogenous cranial bone regeneration. 3D scaffolds consisting of radially aligned nanofibers guided and promoted the migration of bone marrow stem cells from the surrounding region to the center in vitro. These scaffolds showed the highest new bone volume, surface coverage, and mineral density among the tested groups in vivo. The regenerated bone exhibited a radially aligned fashion, closely recapitulating the scaffold’s architecture. The organic …

Method Development Of Standard Dilution Analysis On Molecules And Dissolution Studies Of Ibuprofen Tablets Along With Common Beverage Constituents, Scott Richardson

Master of Science in Chemical Sciences Theses

The United States Pharmacopeia sets the standards for the manufacturing, storage, and analysis of medicinal formulations. One analysis, dissolution testing evaluates the rate at which the medicinal formulation forms a solution to predict in vivo drug release. Dissolution testing on ibuprofen tablets alone and in the presence of ascorbic acid or caffeine was performed to mimic the administration using orange juice or caffeinated soft drinks to assess their impact on the dissolution rate of ibuprofen. Results using the external calibration method produced a dissolution rate of ibuprofen that decreased 4% in the presence of ascorbic acid and increased 1% in …

Degumming Of Hemp Fibers Using Combined Microwave Energy And Deep Eutectic Solvent, Bulbul Ahmed

LSU Master's Theses

Hemp is considered as one of the sustainable agricultural fiber materials. Degumming or surface modification of hemp bast is needed to produce single fibers for ensuing textile and industrial applications. The traditional degumming process necessitates a high amount of alkali, which causes detrimental environmental pollution. This study offers a new method to degum hemp fibers with reduced use of harmful alkali and precious water resources. In this work, hemp bast fibers were degummed by using combined microwave energy and deep eutectic solvent (DES). The properties of hemp fibers manufactured by this method were investigated and compared with the traditional alkali …

Desorption Of Non-Exchangeable Radiocesium In Soil From Fukushima Prefecture, Japan, Grayson Phillips

Master of Science in Chemical Sciences Theses

The Fukushima Daiichi Nuclear Powerplant was struck by an earthquake and a tsunami resulting in the meltdown of four of the six reactor cores operating at the plant. As a result, nuclear waste was released from the plant, contaminating the soil in the region. Most of the contamination was sequestered within the few inches of the soil but unluckily the contamination, radiocesium formed a non-exchangeable bond. The Japanese government bagged this soil and has stored it in fields surrounding the exclusion zone. Long-term storage facilities have not been determined. This is a study of the available resources to determine if, …

Aromatic Substitution: Another View, Charles A. Kingsbury

Department of Chemistry: Faculty Publications

Electrophilic substitution on substituted benzenes is reviewed in terms of molecular orbitals. The HOMO falls into two classes. For all meta director C-X groups, a node passes through the ring and through the substituent C-X bond. With ortho/para director C-X groups, a node perpendicular to the one described above, passes through the ortho-meta bonds.

Gate-Tunable Optical Extinction Of Graphene Nanoribbon Nanoclusters, Erin Sheridan, Gang Li, Mamun Sarker, Shan Hao, Ki-Tae Eom, Chang-Beom Eom, Alexander Sinitskii, Patrick Irvin, Jeremy Levy

Department of Chemistry: Faculty Publications

We investigate the optical response of graphene nanoribbons (GNRs) using the broadband nonlinear generation and detection capabilities of nanoscale junctions created at the LaAlO₃/SrTiO₃ interface. GNR nanoclusters measured to be as small as 1–2 GNRs in size are deposited on the LaAlO₃ surface with an atomic force microscope tip. Time-resolved nonlinear optical probes of GNR nanoclusters reveal a strong, gate-tunable second and third harmonic response, as well as strong extinction of visible to near-infrared light at distinct wavelengths, similar to previous reports with graphene.

Electrochemical Reduction Of Hexavalent Chromium In Acetonitrile Using Glassy Carbon Electrodes, Temitope Jegede

LSU Master's Theses

Hexavalent chromium Cr(VI), a form of chromium mainly generated through industrial processes, has attracted great research interests due to its severe toxicity to biological systems. A common way to remove hexavalent chromium from industrial wastes is through reduction to the non-toxic trivalent state. To this end, methods such as chemical reduction, chemical precipitation and coagulation have been used. However, these methods are limited by poor removal efficiency, formation of secondary pollutants (sludge), and are mostly applicable to aqueous solutions. Recently, electrochemical methods have been investigated for reducing hexavalent chromium, but there is a lack of data on the reduction of …

Functionalized Ionic Liquids For Improved Co2 Hydrogenation Catalysts, Amol Nanduji Jaybhaye

Masters Theses & Specialist Projects

Climate change is one of the biggest problems we are facing today, and anthropogenic greenhouse gases contribute significantly to it. Among greenhouse gasses, carbon dioxide emission is increased drastically and affecting majorly for increasing global temperature, and anything we can do to mitigate carbon dioxide emission will be helpful. A carbon dioxide hydrogenation reaction is a promising technique that can convert carbon dioxide into value-added chemicals, but the reaction rate is slow, and for that, we can use catalysts that will accelerate the reaction rate. Platinum-based nanoparticles have sparked research related to energy and environmental catalysts. Catalytic properties are depending …

The Development Of Novel Carbohydrate-Based Gelators And Their Applications As Advanced Soft Materials, Joedian Morris

Chemistry & Biochemistry Theses & Dissertations

Low molecular weight gelators (LMWGs) are attractive molecules that have been explored extensively due to their practical applications in many disciplines. These small molecules self-assemble forming solid-like gels via three-dimensional cross-linked networks with the solvent as the key component within the matrix. Carbohydrate-based LMWGs are small molecules that can form solid-like gels in water, organic solvents, and aqueous solutions. They have great potential to be utilized in different applications because carbohydrates are biocompatible and can be made from easily accessible and renewable resources. Designing gelators is still a challenge within the field, even though researchers have developed tools to predict …

Bioethanol Production: Glucose Testing And Quantification Using Dns Analysis And Addition Analytical Methods, Dineen Vogler, Barnabas Gikonyo

McNair Scholars Program

The search for alternative ways to create a more sustainable and environmentally friendly source of energy, other than fossil fuels, has been ongoing for many years. Particularly, the production of biofuels has become of interest. One effort has been through the creation of first-generation biofuels that curb greenhouse gas emissions, unlike fossil fuels. However, first generation biofuels lead to the increase in food prices which negatively impacts developing countries, as they use food sources to produce biofuel. To mitigate this issue, second generation biofuels are considered as a better alternative. Instead of hindering the food supply, second generation biofuels aim …

Electrochemical Deposition In Energy Storage Devices, Witness Atutala Martin

Graduate Theses and Dissertations

Metals, whether in a solid or soluble ion form, are a vital part of any electrochemical storage system. More so, Li metal is widely considered as the ideal anode because of its low density and low electrochemical potential (-3.04 V vs. the standard hydrogen electrode – SHE). However, just like most metals, it does not plate or strip evenly during cycling which can lead to cycling performance issues, short cycling lifespans, and even safety concerns brought about by dendrites that can cause internal short-circuiting within cells. This research focused on investigating the electroplating of metals in both aqueous and non-aqueous …

Microfabrication And Electrochemical Characterization Of A Novel Su-8 Probe With An Array Of Individually Addressable Electrodes Suitable For Redox Cycling Experiments In Ultra-Small Volumes, Mahsa Lotfi Marchoubeh

Graduate Theses and Dissertations

Redox cycling is an electrochemical technique that utilizes closely spaced generator and collector electrodes to cycle reversible redox species between their oxidative states. With advantages in signal amplification, selectivity of species based on their electrochemical reaction mechanism, and limited or no background subtraction, this technique is well suited for selective detection of important electrochemically active molecules such as dopamine at basal or slowly changing levels.

Miniaturized medical devices have become an area of great interest for measurement of chemicals in limited volumes with low concentrations or in sensitive tissues. A probe on a polymeric SU-8 substrate with suitable dimensions and …

Microfluidic Paper-Based Analytical Device (Μpad) For Determining Hydroquinone In Facial Whitening Cream Using Phloroglucinol Reagent, Hermin Sulistyarti, Paradhita Ayu Puspitaloka, Boyfannie Ivan Putra, Rurini Retnowati, Herman Tolle

Makara Journal of Science

A microfluidic paper-based analytical device (µPAD) is developed in this work to analyze hydroquinone in facial whitening creams using phloroglucinol. The µPAD features a hydrophobic barrier for detection and was fabricated using a wax printer with Whatman chromatographic paper. Detection was achieved by colorimetry based on the formation of an orange hydroquinone–phloroglucinol complex. The colored reaction product formed on the detection zone of the µPAD was scanned, and the images obtained were processed with Image-J software to determine their color intensity (RGB value). Optimization of the process conditions was conducted to achieve sensitive measurements. The optimum conditions yielding maximum sensitivity …

Ohmic Drop Compensation In Electrochemical Measurement, Jia-Qi Chen, Xu-Xu Ye, Ling-Wen Liao, Zhen Wei, Mian-Le Xu, Yan-Xia Chen

Journal of Electrochemistry

The solution resistance (R_u) between the working electrode (WE) and the reference electrode (RE) may lead to significant Ohmic drop (iR_u) and deviation of actually applied potential at the WE to the desired ones in electrochemical measurement. In the case of high current or large R_u, iR_u compensation is imperative. Errors associated with insufficient compensation of theiR_u drop may significantly affect the accuracy of data measured by conventional electrochemical methods, which may consequently result in wrong judgment and conclusions. In this article, we discuss important factors which may affect the accuracy of …

Multiple Wetting−Dewetting States Of A Water Droplet On Dual- Scale Hierarchical Structured Surfaces, Yurui Gao, Yuan Liu, Jian Jiang, Chongqin Zhu, Craig Zuhlke, Dennis Alexander, Joseph S. Francisco, Xiao Cheng Zeng

Xiao Cheng Zeng Publications

Surfaces with microscale roughness can entail dualscale hierarchical structures such as the recently reported nano/ microstructured surfaces produced in the laboratory (Wang et al. Nature 2020, 582, 55−57). However, how the dual-scale hierarchical structured surface affects the apparent wetting/ dewetting states of a water droplet, and the transitions between the states are still largely unexplored. Here, we report a systematic large-scale molecular dynamics (MD) simulation study on the wetting/dewetting states of water droplets on various dual-scale nano/near-submicrometer structured surfaces. To this end, we devise slab-water/slab-substrate model systems with a variety of dual-scale surface structures and with different degrees of intrinsic …

Dataset For Characterization Of ‘Cool’ And ‘Warm’ White Leds, Edward Navarre

SIUE Faculty Research, Scholarship, and Creative Activity

The emission properties of “cool” and “warm” white LEDs were studied. The suitability of pulse-width modulation as a method to control LED brightness was examined. Both types of LED demonstrated emission standard deviation minima at a PWM frequency greater than 2000 Hz. The functional wavelength ranges of the LEDs were approximated using the linearity of brightness as a function of pulse-width modulation duty-cycle and the root mean squared deviation from mean for absorbance measurements. Both LED types demonstrated good stability in absorbance measurements over long operation times. The “warm” LED demonstrated a broader range of wavelengths useful for spectrophotometry. This …

Assessing Competitive Reaction Rates In The Nitration Of 2-Methylbiphenyl, Biphenyl, And Toluene To Determine Steric Restriction In Resonance-Stabilized Planarization Of The Carbocation Intermediates, Victor A. Hanson, Tristan Wine, Kevin Bartlett, Joshua Padilla, Alessandro Rizzi

Honors Projects

Electrophilic aromatic substitution (EAS) reactions have long been a fundamental addition to sophomore-level organic chemistry classes, allowing students the opportunity to explore the electron donating and withdrawing effects of electrons contained in the substituents of the aromatic reactant. In this paper we present preliminary findings on the nitration of methylated biphenyls using kinetic and regioselective assessments to analyze steric influences on the planarization of 2-methylbiphenyl after EAS nitration. Our preliminary findings show that nitration favors the methylated phenyl ring of 2-methylbiphenyl, indicating that the steric influence of the methyl group restricts planarization of the carbocation intermediate. Furthermore, a competition nitration …

Photosensitization And Analytical Study On Reactive Oxygen Intermediates: Self-Sorting Surface Radicals And “On-Off” Sensitizer Function Mechanisms, Sarah J. Belh

Dissertations, Theses, and Capstone Projects

This thesis consists of four chapters which are detailed below. Chapter 1 is an introductory chapter, which lays out the background and purpose of the research.

Chapter 2 describes a study of the mobility of alkoxy radicals on a surface by detection of their recombination product. A novel method called symmetrical product recombination (SRP) utilizes an unsymmetrical peroxide that upon sensitized homolysis recombines to a symmetrical product [R'OOR → R'O•↑ + •OR → ROOR]. This allows for self-sorting of the radical to enhance the recombination path to a symmetrical product, which has been used to deduce surface migratory aptitude. SPR …

Isolation And Determination Of The Composition And Structural Components That Comprise Dissolved Organic Matter Using Normal Phase Liquid Chromatography, Jonathan A. Long Jr

LSU New Orleans Theses and Dissertations

A comprehensive understanding of the reactivity associated with organic carbon is critical for recognizing the behavior of newly formed compounds in aquatic environments. In an effort to study the reactivity of complex mixtures, understanding the different processes affiliated with them are key. Understanding the reactivity associated with organic carbon can help to improve chromatographic separation. Using a combination of light and heavy crude oil, a separation procedure was developed to obtain a complete representation of the aromatic subfraction of the crude oil sample. The crude oils were separated into four distinct fractions based on the number of condensed aromatic rings …