Life Sciences Commons^™

Variability Of The Proximate And Protein Composition Of Camel Milk (Camelus Dromedarius), Huda Musa Elsayed Mohamed

Dissertations

Dromedary camel milk (Camelus dromedarius) has unique physical, nutritional, and technological properties when compared with other milk. Unlike bovine milk, the processing of camel milk into fermented products and its treatment using ultra-high temperatures is technically challenging. Therefore, this research aimed to determine the variability in the proximate composition and the protein composition of camel milk collected from individual animals that are reared under intensive management in the UAE. To determine the proximate composition of samples (n = 217) were analyzed by NIR and MIR spectroscopy methods. The results obtained by the two methods were also compared. The …

Improving Coupled Enzyme Assays With Capillary Electrophoresis, Thu Hoai Nguyen

LSU Doctoral Dissertations

The goal of this project is to address limitations of coupled enzyme assays using capillary electrophoresis (CE). In some enzyme assays, it is ineffective to directly detect products and substrates spectroscopically (absorption or fluorescence). Coupling the enzyme-catalyzed reaction of interest with another enzyme-catalyzed reaction allows for indirect detection of product formation or substrate depletion for the target enzyme. While conventional coupled enzyme assays are facile for kinetic measurements, they can be problematic for inhibition screening due to spectral and inhibitor interferences. To address these limitations of coupled assays, CE has been used to develop enzyme assays for acetyl-coenzyme A carboxylase …

Short-Chained Oligo(Ethylene Oxide)-Functionalized Gold Nanoparticles: Realization Of Significant Protein Resistance, Kathryn R. Riley, C. M. Sims, I. T. Wood, D. J. Vanderah, M. L. Walker

Chemistry & Biochemistry Faculty Works

Protein corona formed on nanomaterial surfaces play an important role in the bioavailability and cellular uptake of nanomaterials. Modification of surfaces with oligoethylene glycols (OEG) are a common way to improve the resistivity of nanomaterials to protein adsorption. Short-chain ethylene oxide (EO) oligomers have been shown to improve the protein resistance of planar Au surfaces. We describe the application of these EO oligomers for improved protein resistance of 30 nm spherical gold nanoparticles (AuNPs). Functionalized AuNPs were characterized using UV-Vis spectroscopy, dynamic light scattering (DLS), and zeta potential measurements. Capillary electrophoresis (CE) was used for separation and quantitation of AuNPs …

Study Of The Genetic Diversity Of The Aflatoxin Biosynthesis Cluster In Aspergillus Section Flavi Using Insertion/Deletion Markers In Peanut Seeds From Georgia, Usa, Paola C. Faustinelli, Edwin R. Palencia, Victor S. Sobolev, Bruce W. Horn, Hank T. Sheppard, Marshall C. Lamb, Xinye M. Wang, Brian E. Scheffler, Jaime Martinez Castillo, Renee S. Arias

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

Aflatoxins are among themost powerful carcinogens in nature. The major aflatoxin-producing fungi are Aspergillus flavus and A. parasiticus. Numerous crops, including peanut, are susceptible to aflatoxin contamination by these fungi. There has been an increased use of RNA interference (RNAi) technology to control phytopathogenic fungi in recent years. In order to develop molecular tools targeting specific genes of these fungi for the control of aflatoxins, it is necessary to obtain their genome sequences. Although high-throughput sequencing is readily available, it is still impractical to sequence the genome of every isolate. Thus, in this work, the authors proposed a workflow …

Analysis Of Plant Analytes Using Capillary Electrophoresis And High Performance Liquid Chromatography, Umme Kalsoom

Theses: Doctorates and Masters

Plants contain an enormous array of organic and inorganic components, the analysis for which may involve a wide range of methods. The focus of this study was to develop high performance liquid chromatography and capillary electrophoresis methods for the analysis of three classes of analytes: osmoregulants, minerals and amino acids.

Firstly, this study explored the potential of capillary electrophoresis for the analysis of three very common osmoregulants (proline, glycine betaine and mannitol). A diverse array of methods has been reported for determining each of these analytes, however, the literature on osmoregulants and their analysis is quite disjointed and traverses both …

Microfluidic Devices With Integrated Sample Preparation For Improved Analysis Of Protein Biomarkers, Pamela Nsang Nge

Theses and Dissertations

Biomarkers present a non-invasive means of detecting cancer because they can be obtained from body fluids. They can also be used for prognosis and assessing response to treatment. To limit interferences it is essential to pretreat biological samples before analysis. Sample preparation methods include extraction of analyte from an unsuitable matrix, purification, concentration or dilution and labeling. The many advantages offered by microfluidics include portability, speed, automation and integration. Because of the difficulties encountered in integrating this step in microfluidic devices most sample preparation methods are often carried out off-chip. In the fabrication of micro-total analysis systems it is important …

Capillary And Microchip Electrophoresis For The Monitoring Of Disease Causing Amyloid Proteins, Elizabeth Nancy Pryor

Graduate Theses and Dissertations

The detection of oligomers and aggregates formed by two amyloid proteins, insulin and amyloid-beta (AB), is of particular importance due to the role which these species play in Diabetes and Alzheimer's disease, respectively. However, existing techniques are limited in the ability to detect insulin and AB; oligomers due to the fact that these early aggregates are transient, present at low concentrations, and difficult to isolate. Improvements must be made to existing techniques or alternative techniques must be explored in order to identify and quantify the size of these oligomeric and aggregate species without disrupting their structure.

Capillary and microchip electrophoresis …

Integrated Affinity Column Capillary Electrophoresis Microdevices For Biomarker Analysis, Weichun Yang

Theses and Dissertations

In this dissertation, microfluidic systems that integrate antibody-based sample preparation methods with electrophoretic separation are developed to analyze multiple biomarkers in a point-of-care setting. To form an affinity column, both monolith materials and wall-coated channels were explored. I successfully demonstrated that monolith columns can be prepared in microfluidic devices via photopolymerization. The selectivity of monolith columns was improved by immobilizing antibodies on the surface. These affinity columns can selectively enrich target analytes and reduce the signal of contaminant proteins up to 25,000 fold after immunoaffinity extraction. These results clearly demonstrate that microchip affinity monoliths can selectively concentrate and purify target …

A Capillary Electrophoresis Method For Evaluation Of Abeta Proteolysis In Vitro, Benjamin J. Alper, Walter K. Schmidt

Chemistry & Physics Faculty Publications

According to the amyloid hypothesis, Aβ peptides are neurotoxic and underlie development and progression of Alzheimer’s disease (AD). Multiple Aβ clearance mechanisms, including destruction of the peptides by proteolytic enzymes, are hypothesized to regulate physiological Aβ peptide levels. The insulin-degrading enzyme (IDE) is considered one of the predominant enzymes having Aβ degrading activity. Despite its putative role in protecting against AD, relatively few methods exist for studying IDE activity in vitro. We report the application of capillary electrophoresis (CE) as a novel method for evaluating IDE-mediated Aβ 1–40 proteolysis. This method employs chemically unmodified substrates that are readily obtained …

Microchip Liquid Chromatography And Capillary Electrophoresis Separations In Multilayer Microdevices, Hernan Vicente Fuentes

Theses and Dissertations

In this dissertation, several microfabricated devices are introduced to develop new applications in the area of chemical analysis. Electrochemical micropumps, chip-based liquid chromatography systems and multilayer capillary electrophoresis microdevices with crossover channels were fabricated using various substrates such as poly(dimethylsiloxane) (PDMS), glass, and poly(methyl methacrylate) (PMMA). I have demonstrated pressure-driven pumping of liquids in microfabricated channels using electrochemical actuation. PDMS-based micropumps were integrated easily with channel-containing PMMA substrates. Flow rates on the order of ~10 µL/min were achieved using low voltages (10 V). The potential of electrolysis-based pumping in microchannels was further evaluated for pressure driven microchip liquid chromatography (LC). …

Capillary Electrophoresis Of Proteins With Selective On-Line Affinity Monoliths, Jenny Marcela Armenta Blanco

Theses and Dissertations

The analysis of proteins in biological fluids by capillary electrophoresis (CE) is of interest in clinical chemistry. However, due to low analyte concentrations and poor concentration limits of detection (CLOD), protein analysis by this technique is frequently challenging. Coupling preconcentration techniques with CE greatly improves the CLOD. An on-line preconcentration-CE method that can selectively preconcentrate any protein for which an antibody is available would be very useful for the analysis of low abundance proteins and would establish CE as a major tool in biomarker discovery. To accomplish this, an on-line protein G monolithic preconcentrator CE system for enrichment and separation …

Membrane-Based Protein Preconcentration Microfluidic Devices, Yi Li

Theses and Dissertations

Interest in microchip capillary electrophoresis (CE) is growing due to the rapid analysis times provided and small sample input requirements. However, higher-concentration samples are typically needed because of the small (~pL) detection volumes in these devices. I have made membrane-based protein preconcentration systems in capillary and microchip designs to increase the detectability of low-concentration biological samples. A photopolymerized ion-permeable membrane interfaced with a microchannel in poly(methyl methacrylate) (PMMA) formed the preconcentrator. When a voltage was applied between the sample reservoir and the ionically conductive membrane in a capillary-based system, R-phycoerythrin was concentrated more than 1,000 fold, as determined by laser-induced …

Analysis Of Clinically Important Compounds Using Electrophoretic Separation Techniques Coupled To Time-Of-Flight Mass Spectrometry, Zlatuse Durda Peterson

Theses and Dissertations

Capillary electrophoretic (CE) separations were successfully coupled to time-of-flight mass spectrometric (TOFMS) detection for the analysis of three families of biological compounds that act as mediators and/or indicators of disease, namely, catecholamines (dopamine, epinephrine, norepinephrine) and their O-methoxylated metabolites (3-methoxytyramine, norepinephrine, and normetanephrine), indolamines (serotonin, tryptophan, and 5-hydroxytryptophan), and angiotensin peptides. While electrophoretic separation techniques provided high separation efficiency, mass spectrometric detection afforded specificity unsurpassed by other types of detectors.

Both catecholamines and indolamines are present in body fluids at concentrations that make it possible for them to be determined by capillary zone electrophoresis coupled to TOFMS without employing any …

Detection Of Moniliformin In Maize Using Capillary Zone Electrophoresis, C. M. Maragos

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

Moniliformin is a mycotoxin produced by certain fungi pathogenic to maize. It is capable of causing disease in domestic animals, possibly through inhibition of pyruvate dehydrogenase. Testing for MON commonly involves extraction of maize, isolation of moniliformin using solid-phase extraction columns and detection with high-performance liquid chromatography (HPLC) or gas chromatography. A capillary zone electrophoresisdiode array detection (CZE-DAD) method for determination of moniliformin in maize is reported. The extraction and isolation procedures are similar to those of a commonly used HPLC method, while the detection step requires only 10 min. Sixty-three samples of maize were tested by an established HPLC …

Micellar Electrokinetic Chromatographie Method For The Determination Of Quercetin In Psidium Guajava Leaves, S. Boonkerd, V. Chantarateptawan, K. Kraisintu

The Thai Journal of Pharmaceutical Sciences

The analysis of quercetin in Psidium guajava leaves by micellar electrokinetic chromatography was described. The results indicated that quercetin in Psidium guajava leaves was mostly in the form of glycosides and the analysis of total quercetin could be ...

Development And Optimisation Of A Micellar Electrokinetic Capillary Chromatography Method For The Separation And Identification Of Phenolics From Eucalypt Species, Andrew J. Tromans

Theses : Honours

Several buffers were examined for their ability to separate a complex mixture of phenolic compounds using micellar electrokinetic capillary chromatography (MEKC). The phenolic mixture included simple phenols, phenolic acids and coumarins. Of the different buffers examined, 6 mM borate, 10 mM phosphate, 100 mM SDS, pH 8.3 gave the best separation. The ability of organic modifiers, complexation agents such as α cyclodextrin, β cyclodextrin and mixed SDS I Brij 35 micelles to improve the separation and peak retention time reproducibility of the buffer system was investigated. Baseline separation of the 18 phenolics was achieved by the 6 mM borate, 10 …