Analytical Chemistry Commons^™

Study Of Electron Transfer Through The Reductase Domain Of Neuronal Nitric Oxide Synthase And Development Of Bacterial Nitric Oxide Synthase Inhibitors, Yue Dai

ETD Archive

Crystal structure of neuronal Nitric Oxide Synthase reductase (nNOSr) implies that large-scale domain motion is essential for electron transfer. However, the details are not well understood. To address this, we generated a functioning “Cys-lite” version of nNOSr and then replaced the nNOSr Glu816 and Arg1229 residues with Cys in the FMN and FAD domains (CL5SS) in order to allow cross-domain disulfide bond formation under pH 9 or to cross-linking using bis-maleimides. Cross-linked CL5SS exhibited a =95% decrease in cytochrome c reductase activity and reduction of the disulfide bond restored the activities. The results demonstrate that a conformational equilibrium involving FMN …

Application Of Advanced Analytical Technologies To Drug Development Studies And Cancer Detection, Ramakrishna Reddy Voggu

ETD Archive

In the past decade, bioanalytical method development has become an integral part of the clinical diagnosis, biomarker discovery, and drug discovery and development. The new and emerged bioanalytical techniques allow the quantitative and qualitative analysis of bio molecules with remarkably high sensitivity and specificity. Specifically, these bioanalytical methods based on LC-MS and methylation-specific PCR are well suited for detecting low-abundance metabolites in various biological fluids and DNA in plasma and tissues for biomarker investigation. They offer great clinical promise for early disease diagnosis and therapeutic intervention. This dissertation broadly organized into two parts, part one talks about the application of …

Determination Of Hexavalent Chromium (Cr(Vi)) Concentrations Via Ion Chromatography And Uv-Vis Spectrophotometry In Samples Collected From Nacogdoches Wastewater Treatment Plant, East Texas (Usa), Kefa Karimu Onchoke, Salomey A. Sasu

Faculty Publications

The concentration of hexavalent chromium (Cr(VI)), a toxic environmental pollutant and carcinogen, was determined in samples collected from Nacogdoches Wastewater Treatment Plant (NWWTP) using ion chromatography and UV-visible spectrophotometry (IC, UV-Vis). On reaction with 1,5-diphenylcarbazide (DPC) Cr+6 forms a 1,5-diphenylcarbazide-Cr(VI) complex, which is then analyzed at 530nm and 540nm, respectively. Via ion chromatography Cr(VI) concentrations were in the range of 0.00190 ± 0.0020 and 0.0010 ± 0.0006ppm at the influent and effluent, respectively. With the use of standard addition wastewater samples were spiked with a 0.5ppm Cr(VI) standard of various amounts and subsequently analyzed with UV-Vis spectrophotometry. The spiked concentrations …

Spectrophotometric Analysis Of Urinary Iodine In 18-22 Year-Old Women In Central Minnesota, Haley Chatelaine

All College Thesis Program, 2016-2019

Iodine is an overlooked but incredibly important micronutrient, especially with regard to early fetus development. The United States does not mandate salt iodization, so widely consumed processed foods are not likely to contain iodized salt, which may potentially put the population at risk for developing iodine deficiencies. Therefore, the purpose of this study is to correspond iodine intake to iodine status and establish effective methods for determining a relationship between the two. Subjects (n=23) completed a food survey and supplied 50mL urine samples to compare an estimated average daily iodine intake based on foods over the course of a week …

Hlarp7 C-Terminal Domain Contains An Xrrm That Binds The 3' Hairpin Of 7sk Rna, Catherine D. Eichhorn, Rahul Chug, Juli Feigon

Department of Chemistry: Faculty Publications

The 7SK small nuclear ribonucleoprotein (snRNP) sequesters and inactivates the positive transcription elongation factor b (P-TEFb), an essential eukaryotic mRNA transcription factor. The human La-related protein group 7 (hLARP7) is a constitutive component of the 7SK snRNP and localizes to the 3' terminus of the 7SK long noncoding RNA. hLARP7, and in particular its C-terminal domain (CTD), is essential for 7SK RNA stability and assembly with P-TEFb. The hLARP7 N-terminal Lamodule binds and protects the 3' end from degradation, but the structural and functional role of its CTD is unclear.We report the solution NMR structure of the hLARP7 CTD and …

Analytic Ab Initio-Based Molecular Interaction Potential For The Bro·H2O Complex, Ross D. Hoehn, Sachin D. Yeole, Sabre Kais, Joseph S. Francisco

Department of Chemistry: Faculty Publications

Radical halogen oxide species play important roles within atmospheric processes, specifically those responsible for the removal of O3. To facilitate future investigations on this family of compounds, RCCSD(T)/aug-cc-pVQZ-level electronic structure calculations were employed to generate individual-molecule optimized geometries, as well as to determine the global minimum energy structure for the BrO·H₂O complex. This information facilitated the generation of several one-dimensional potential energy surface (PES) scans for the BrO·H₂O complex. Scans were performed for both the ground state and the first excited state; this inclusion is due to a low-lying first electronic excited-state energy. These rigid-geometry PES …

Ring Closures And The Hammond Postulate, Charles A. Kingsbury

Department of Chemistry: Faculty Publications

This work reports an investigation of ring closure processes in relation to the Hammond postulate. Calculations favor the importance of thermodynamics, not kinetics, as the basis for the Hammond postulate. A kinetically rapid, but thermodynamically unfavorable reaction is shown to resemble product. The ease of ring closure to three-membered rings, compared to four-membered rings, is thought to be associated with conformational mobility and perhaps vibrations coupled to the reaction coordinate motion in the case of four-membered rings.

Profiling Cell Surface Sialylation And Desialylation Dynamics Of Immune Cells, Dan Wang

ETD Archive

Sialic acids (SAs) are a diverse family of naturally occurring 2-keto-3-deoxy-nononic acids that are involved in a wide range of biological processes, including early fetal development, cellular recognition, and utilization by microbes. While it is clear that cell surface SAs are highly involved in the immune system, the sialylation status of individual immune cells and functions are still unknown. In this study, I combined the newly developed LC-MS/MS methods with flow cytometry and confocal microscopy to systematically study the sialylation and desialylation dynamics of macrophages at different conditions.

First, I developed an accurate LC-MS/MS method to quantify free SA in …

The Role Of Rnase L In Type I Diabetes And Development Of Quantitative Lc-Ms/Ms Methods For The Pharmacological Studies Of Anti-Cancer Drug Candidates, Chun Zeng

ETD Archive

PROJECT I: The cause of type I diabetes continues to be a focus of investigation. In this study, we found that 2-5A dependent RNase L (RNase L), an IFN-a-inducible enzyme that functions in IFN action against viruses and cell proliferation, played an important role in dsRNA-induced onset of type I diabetes. By using RNase L deficient RIP-B7.1 mice which are more vulnerable to environmental harmful factors such as viral infection, we demonstrated that deficiency of RNase L in mice resulted in a significant delay of diabetes onset induced by polyinosinic:polycytidylic acid (poly I:C), a type of dsRNA, and streptozotocin (STZ). …

Use Of 17o-Nmr Spectroscopy To Study The Coordination Chemistry Of Trivalent Lanthanide Ions In Solution, Zhijin Lin

Wayne State University Dissertations

Trivalent lanthanide (Ln3+)-containing complexes have a number of important applications in molecular imaging, catalysis, medical diagnosis, information storage, and environmental sensing. The properties of Ln3+-containing complexes that are useful for these applications are influenced by coordination chemistry, including the number of coordinated ligands and ligand-exchange rates. The coordination numbers for water molecules bound to Eu3+ and Tb3+ have been studied by luminescence-decay measurements; however, the coordination numbers of other important oxygen-containing functional groups such as ketones, esters, ethers, sulfonyls, amides, phosphine oxides, and aldehydes have not been as thoroughly studied in solution because of the lack of hydroxyl groups that …

Novel Approaches For Assessment Of Copper Toxicity: Fast Scan Cyclic Voltammetry And Optical Bioassays, Annette R. Tremonti

Wayne State University Dissertations

Anthropogenic activities negatively impact fresh water ecosystems through toxic contaminants that are released into the environment. Copper (Cu) is a water contaminant that is fundamentally persistent once introduced into the environment that has the potential for bioaccumulation. Although Cu toxicity has been studied for decades, there is still a continuing problem with new sources and pathways. New approaches are needed to understand distribution and transport of Cu and its potential for complex biological impacts beyond the simple assessment of lethality. Several novel approaches were used in this research project to advance our understanding of Cu toxicity, including fast scan cyclic …

Live, Attenuated Vaccines And Methods Of Making And Using, Jiantao Guo, Qingsheng Li, Wei Niu, Yue Li, Nanxi Wang

Department of Chemistry: Faculty Publications

A live, attenuated HIV vaccine is provided, and methods of making a atenuated HIV vaccine are provided.

Development Of Single And Array Electro-Chemical Sensors For Real-Time Trace Metal Analysis In Aqueous Environmental Media, Yuanyuan Yang

Wayne State University Dissertations

Detection of trace metals has great importance in environmental and biological applications. While traditional electrochemical techniques have played critical roles in this field, their usefulness is limited by temporal resolution, Hg toxicity and stability concerns. Recently, we developed a method using fast-scan cyclic voltammetry (FSCV) at carbon-fiber microelectrodes (CFMs) to achieve rapid measurement of metal ions with high sensitivity, selectivity, and stability. Through optimizations this method showed strengths in real-time trace metal analysis. ‬‬‬‬‬‬

‪Analytical selectivity was improved via covalent functionalization on CFMs. We employed diazonium electrochemical reduction followed by click chemistry to create robust covalent attachments. We showcased its …

Unraveling A Generic Growth Pattern In Structure Evolution Of Thiolate-Protected Gold Nanoclusters, Wen Wu Xu, Yadong Li, Yi Gao, Xiao Cheng Zeng

Xiao Cheng Zeng Publications

Precise control of the growth of thiolate-protected gold nanoclusters is a prerequisite for their applications in catalysis and bioengineering. Here, we bring to bear a new series of thiolateprotected nanoclusters with a unique growth pattern, i.e., Au₂₀(SR)₁₆, Au₂₈(SR)₂₀, Au₃₆(SR)₂₄, Au₄₄(SR)₂₈, and Au₅₂(SR)₃₂. These nanoclusters can be viewed as resulting from the stepwise addition of a common structural motif [Au₈(SR)₄]. The highly negative values of the nucleus-independent chemical shift (NICS) in the center of the tetrahedral Au4 …

Tuning The Electronic Properties Of Monolayer And Bilayer Ptse2 Via Strain Engineering, Pengfei Li, Lei Li, Xiao Cheng Zeng

Xiao Cheng Zeng Publications

The recently synthesized monolayer PtSe₂ belongs to the class of two-dimensional transition metal dichalcogenide (TMDC) materials (Nano Lett., 2015, 15, 4013). Based on first-principles calculations, we show that the band gaps of monolayer and bilayer PtSe₂ can be tuned over a wide range via strain engineering. Both isotropic and uniaxial strains are investigated. For bilayer PtSe₂, the vertical out-of-plane strain is also considered. In most cases, the strain can reduce the band gap except for the bilayer PtSe₂ under the isotropic strain (Ɛ≤ 4%) for which the band gap can be slightly enlarged. Importantly, the …

Unraveling A Generic Growth Pattern In Structure Evolution Of Thiolate-Protected Gold Nanoclusters, Wen Wu Xu, Yadong Li, Yi Gao, Xiao Cheng Zeng

Xiao Cheng Zeng Publications

Precise control of the growth of thiolate-protected gold nanoclusters is a prerequisite for their applications in catalysis and bioengineering. Here, we bring to bear a new series of thiolateprotected nanoclusters with a unique growth pattern, i.e., Au₂₀(SR)₁₆, Au₂₈(SR)₂₀, Au₃₆(SR)₂₄, Au₄₄(SR)₂₈, and Au₅₂(SR)₃₂. These nanoclusters can be viewed as resulting from the stepwise addition of a common structural motif [Au₈(SR)₄]. The highly negative values of the nucleus-independent chemical shift (NICS) in the center of the tetrahedral Au …

Mechanistic Study Of Pressure And Temperature Dependent Structural Changes In Reactive Formation Of Silicon Carbonate, Bingyan Qu, Dongdong Li, Lei Wang, Jili Wu, Rulong Zhou, Bo Zhang, Xiao Cheng Zeng

Xiao Cheng Zeng Publications

The discovery of the silicon carbonate through chemical reaction between porous SiO₂ and gaseous CO₂ addressed a long-standing question regarding whether the reaction between CO₂ and SiO₂ is possible. However, the detailed atomic structure of silicon carbonate and associated reaction mechanism are still largely unknown. We explore structure changes of silicon carbonate with pressure and temperature based on systematic ab initio molecular dynamics simulations. Our simulations suggest that the reaction proceeds at the surface of the porous SiO₂. Increasing number of CO₂ molecules can take part in the reaction by increasing either the …

Surprising Impact Of Remote Groups On The Folding–Unfolding And Dimer-Chain Equilibria Of Bifunctional H-Bonding Unimers, Rui Liu, Shuang Cheng, Erin S. Baker, Richard D. Smith, Xiao Cheng Zeng, Rui Liu

Xiao Cheng Zeng Publications

Oligoamide 1, consisting of two H-bonding units linked by a trimethylene linker, was previously found to form a very stable, folded dimer. In this work, replacing the side chains and end groups of 1 led to derivatives that show the surprising impact of end groups on the folding and dimer-chain equilibria of the resultant molecules.

Paper/Polymer Hybrid Microfluidic Biochips For Infectious Disease Diagnosis, Maowei Dou

Open Access Theses & Dissertations

Infectious diseases frequently cause public health concerns and they often occur in high-poverty regions. Hence, a simple and low-cost method is in great need for immediate and early diagnosis of infectious diseases. Recently, microfluidic lab-on-a-chip offers a unique opportunity for various biomedical applications. Since different chip substrates have different advantages and limitations, hybrid devices can draw more benefits from different substrates. Therefore, we have developed three paper/polymer hybrid microfluidic biochips integrated with loop-mediated isothermal amplification (LAMP) for high-sensitivity infectious disease diagnosis.

We for the first time developed a low-cost paper/polydimethylsiloxane (PDMS) hybrid microfluidic biochip for rapid, sensitive and instrument-free detection …

Development Of Direct Analysis In Real Time-High Resolution Mass Spectrometry (Dart-Hrms) And Statistical Analysis Tools For The Identification And Classification Of Psychoactive Plant Drugs, Ashton Danielle Lesiak

Legacy Theses & Dissertations (2009 - 2024)

In current forensic testing, a new pattern is emerging where the drugs that are submitted to crime labs for analysis are no longer restricted to well-characterized substances such as cocaine, heroin and tetrahydrocannabinol (THC). The appearance of new psychoactive substances (NPS) in forensic laboratories, including synthetic alternatives to scheduled substances and plant-based psychotropics, has highlighted issues that traditional analytical methods such as gas chromatography- and liquid chromatography-mass spectrometry impose in the characterization of these samples. These can include lengthy extractions, derivatization steps, pH adjustments and/or a host of other procedures. Since the creation of legislation to address the use of …