Digital Commons Network^™

Ratiometric Copper(Ii) Indicators Based On Poly(N-Isoproprylacrylamide) And Fluorescence Resonance Energy Transfer, Shaojun Yao

Doctoral Dissertations

An approach to ratiometric fluorescence detection of Cu(II) ions was devised by copolymerizing N-isopropylacrylamide with small percentages of bipyridine and amine monomers. The copolymer was divided into two portions. The amine group on one portion was functionalized with AlexaFluor555 (donor fluorophore) and the other with AlexaFluor647 (acceptor fluorophore). The indicator consists of a mixture of these two portions. Aggregation above the lower critical solution temperature (LCST) of this copolymer brings about a large increase in fluorescence resonance energy transfer (FRET). Addition of Cu(II) to the aggregated copolymer introduces charge onto the backbone, causing the copolymer to deaggregate with a resulting …

Calibration, Optimization, And Deployment Of Ptr-Ms Instruments During The Airmap Project, Karl B. Haase

Doctoral Dissertations

Proton Transfer Reaction Mass Spectrometry (PTR-MS) is an increasingly popular technique for monitoring volatile organic compounds with high sensitivity and time resolution. This dissertation encompasses three different projects, sharing the common theme of expanding the knowledge and utility of the technique.

The first project focuses on elucidating the ion chemistry that occurs within the PTR-MS drift tube reaction chamber. The PTR-MS uses a differentially pumped skimmer to prevent excess water from the ion source from entering the drift tube reaction chamber. By placing a metering valve in between the skimmer region and the pump, it was possible to control the …

Chromatographic Studies And Analytical Methods Development For Selected Tetraazamacrocycles And Their Copper(Ii) Complexes, Ilia Terova

Doctoral Dissertations

Cu(II)-azamacrocyclic complexes are of current interest due to their potential application as copper-64 radioisotope-based imaging and therapeutic agents. The development of separation conditions is important in evaluating their purity as well as assessment of their physical properties including conditional formation constants, acid dissociation constants and lipophilicity, which can have a major bearing on the in vivo behavior of these complexes. This study evaluates the chromatographic properties of a series of copper (II) complexes of chelating cross-bridged tetraamine ligands with methanephosphonate arms having different ring sizes (12- and 14-membered) and different pendant arm moetics. Cu-CB-DO2POEt and Cu-CB-TE2POEt are two complexes with …

Volatile Organic Compounds In The New England Troposphere: Atmospheric Chemistry And Measurement Techniques, Jesse L. Ambrose

Doctoral Dissertations

Atmospheric measurements made at Appledore Island, Maine were used to investigate nighttime nitrate radical (NO3) chemistry and its significance for the nitrogen oxides (NOx = NO + NO2) budget in the Gulf of Maine region during the summer of 2004 International Consortium for Atmospheric Research on Transport and Transformation field campaign. Removal of NOx was strongly dependent on reactions of NO3 with biogenic volatile organic compounds and the fate of dinitrogen pentoxide (N 2O5). For three case studies, temporal profiles of NO 3 were calculated from measured parameters. Comparisons between measured and calculated NO3 mixing ratios highlighted significant uncertainties in …

Ratiometric Fluorescent Metal Ion Indicators Based On Functionalized Poly(N -Isopropylacrylamide), Jie Du

Doctoral Dissertations

A novel type of ratiometric fluorescent indicator based on the phase transition of a well-known stimuli-responsive polymer poly(N-isopropylacrylamide) (PNIPAM) is presented. The sensing mechanism involves the polymer conformational change resulting from charge neutralization by the analyte metal ions. The ultimate goal is to develop ratiometric fluorescent indicators for free Cu(II) in environmental water analysis.

The indicators are copolymers of N-isopropylacrylamide (NIPAM) with small percentages of fluorophores and ligand monomers. The charges on the ligands prevent PNIPAM from collapsing unless neutralized upon metal ion chelation. The polymer phase transition is transduced by either fluorescence solvatochromism or fluorescence resonance energy transfer (FRET), …

Modeling Congenital Disorders Of Glycosylation In Caenorhabditis Elegans: Genetic Influences And Structural Consequences Of N-Linked Glycosylation, Weston Booth Struwe

Doctoral Dissertations

The attachment of oligosaccharides to the amide nitrogen of asparagine side chains in proteins is a fundamental process occurring in all metazoans. This process, known as N-glycosylation, is complex and is achieved by the precise interactions of various cellular components. The initial stage of N-glycosylation occurs in the endolasmic reticulum and is preserved among eukaryotes. Glycans are further developed in the Golgi and the structural complexity depends greatly on the animal species, tissue and developmental stage. Oligosaccharides are unique biomolecules because unlike DNA or proteins, no primary sequence exists nor is its' synthesis template driven. A major goal of glycobiologist …

Glycan Characterizations With Application In Metal Ion Binding, The 1918 Influenza Virus Neuraminidase Formation And Human Receptors, Hui Zhou

Doctoral Dissertations

The EP glycoprotein, the major protein component isolated from the EP fluid of the mollusc, Mytilus edulis, is known to bind many metal ions and to contain 14.3% of carbohydrate in weight. To structurally evaluate the sugar function of this glycoprotein, a new mass spectrometry-based strategy was applied with a focus on the comprehensive characterization of its N-glycans. This included: (a) accurate mass measurement and GC/MS to determine the monosaccharide compositions; (b) positive ion CID-MS n to disassemble the deuterated permethylated derivates (CD3 ) to reveal the antenna sequence, and natural methoxyl group location; (c) negative ion CID-MSn on native …

Chemical Sensors Based On Swellable Polymer Microparticles And Molecular Imprinted Polymers, John Ong'any Osambo

Doctoral Dissertations

Swellable thermoresponsive and lightly cross-linked polymer microparticles were prepared for the development of chemical sensors for various target analytes. The swelling and shrinking of the polymer particles as a function of concentration of target analytes has been investigated using turbidity and fluorescence measurements at suitable pH values.

Chemical sensors that respond to transition metal ions such as Cu 2+, Ni2+, Zn2+, and Pb2+ were prepared by copolymerizing N-Isopropylacrylamide (NIPAAm) with ligands such as; 2,2'-acylamidodiacetic acid (AIDA), dibutyl-2,2'-(3 vinylphenylazanediyl) diacetate (DVPAA), N-((4'-methyl-2,2'-bipyridin-4yl)methyl)-N-propylacrylamide (NMPPAAm), and N,N-bis(pyridine-2-ylmethyl)prop-2-en-1-amine (NBPMPA). The microparticles were either labeled with 9-vinylanthracene (9-VA)/2-Naphthylmethacrylate (2-NMA), or fluorescein o-acrylate/methacryloxethyl thiocarbonyl rhodamine B …

Glyspy: A Software Suite For Assigning Glycan Topologies From Sequential Mass Spectral Data, Anthony Lapadula

Doctoral Dissertations

GlySpy is a suite of algorithms used to determine the structure of glycans. Glycans, which are orderly aggregations of monosaccharides such as glucose, mannose, and fucose, are often attached to proteins and lipids, and provide a wide range of biological functions. Previous biomolecule-sequencing algorithms have operated on linear polymers such as proteins or DNA but, because glycans form complicated branching structures, new approaches are required. GlySpy uses data derived from sequential mass spectrometry (MSn), in which a precursor molecule is fragmented to form products, each of which may then be fragmented further, gradually disassembling the glycan. GlySpy resolves the structures …

Development And Application Of Methods For Analysis Of Fungal Glycosphingolipid Structure And Functional Interactions, Emma Adhiambo Arigi

Doctoral Dissertations

Fungal lectins from the mushrooms Polyporus squamosus and Coprinus cinereus have an affinity for beta-galactosides, with extended binding sites for the non-reducing terminal trisaccharide sequence NeuAcalpha2→6Galbeta1→4Glc/GlcNAc, and substituted beta-galactosides resembling mammalian blood group determinants, respectively. In considering the possibility that glycosylinositol phosphorylceramides (GIPCs) could be endogenous ligands of such fungal lectins, structural characterization of glycosphingolipids (GSLs) from the fruiting bodies of these mushrooms was performed. The extraction, isolation and purification of the lipids, and their subsequent characterization by nuclear magnetic resonance (NMR), mass spectrometry (MS) and gas chromatography-mass spectrometry (GC-MS) was performed. One monohexosylceramide (CMH) and three major GIPCs were …

Investigation Of Copper(Ii) Complexes: I Copper(Ii) Complexes Of Tryptophan And Its Analogues As Postcolumn Interaction Components For Indirect Fluorescence Detection Of Amino-Containing Analytes Ii High-Performance Liquid Chromatographic Separation Of Copper(Ii) Azamacrocyclic Complexes, Xiaoxuan Shen

Doctoral Dissertations

The initial phase of this project investigates the use of copper(II) complexes of tryptophan and its analogues for indirect fluorescence detection in high-performance liquid chromatography. First, indirect photometric and fluorometric detection in high performance liquid chromatography (HPLC) is reviewed, giving the functional definition of indirect detection employed for this project, distinguishing different approaches to indirect photometric and fluorometric detection in HPLC, and explaining the basis of indirect fluorescence detection using copper(II) complexes of tryptophan and its analogues as postcolumn interaction components. Subsequent studies were conducted to develop and apply indirect HPLC detection for detecting specific mono-amino sugars, glucosamine, galactosamine, and …

Chemical Sensors Based On Swelling Polymer Microspheres And Uncrosslinked Fluorescently-Labelled Molecularly Imprinted Polymers, George K. Mwangi

Doctoral Dissertations

Polymer swelling can be achieved by derivatizing a functional group onto the polymer that selectively binds a particular analyte. For example, at low pH, the particles in a hydrogel membrane swell in response to the increased hydrogen ion concentration and the membrane reflects less light. When the refractive index of the membrane is less than that of the particles, swelling decreases the refractive index of the particles. This brings it closer to the refractive index of the membrane, and decreases the scattering of light making the membrane more transparent.

On the other hand if the refractive index of the membrane …

Chemical Sensors Based On Swellable Molecularly Imprinted Polymer Microspheres In A Hydrogel, Wenzhe Fan

Doctoral Dissertations

A novel design of chemical sensors based on swellable molecularly imprinted polymer microspheres is presented. These sensors were successfully used to measure norephedrine and theophylline in water and in buffer at neutral pH.

A new method was developed for preparing swellable norephedrine templated poly (N-isopropylacrylamide-acrylic acid) (poly NIPA-AAc) particles by suspension polymerization in a perfluorocarbon solvent using ultrasonic emulsion technique. The particles were crosslinked with 5% of N, N'-methlene-bis-acylamide (MBA) using 20% fluorinated surfactant as a stabilizer. The resulting particles were around 6 mum in diameter. HYPAN and poly (vinyl alcohol) (PVA) hydrogels were used to make hydrogel membranes containing …

Magnetoacoustic Chemical Sensors Based On Swellable Polymer Microspheres, Huqun Liu

Doctoral Dissertations

The goal of this dissertation was to investigate chemical applications of magnetoacoustic sensors based on swellable polymer microspheres. The magnetoacoustic sensor was used to monitor viscosity of starch solution, water loading, and 2-hydroxyethyl methacrylate polymerization.

Poly(vinylbenzyl chloride) (polyVBC) microspheres were prepared by suspension polymerization and then derivatized to introduce dicarboxylate groups onto the polymer backbone. Poly(vinylbenzyl chloride-trichlorophenyl acrylate) (polyVBC-TCPA) microspheres were prepared by dispersion polymerization and then derivatized to introduce amine groups onto the polymer backbone. These derivatized polymer microspheres swell and shrink with changing pH. They were entrapped in a hydrogel membrane and the membrane turbidity was investigated by …

Improved Swellable Polymer Microspheres For Chemical Sensing, Necati Kaval

Doctoral Dissertations

Derivatized lightly crosslinked polymer microspheres that swell and shrink as a function of pH have been investigated to develop polymeric transduction elements for fiber optic sensors and other sensors. The microspheres were immobilized in hydrogels forming a membrane. The membranes look turbid because of the difference between the refractive index of hydrogel and the refractive index of microspheres. As the microspheres swell as a function of pH, their refractive index decreases approaching the refractive index of the hydrogel. As a result, the turbidity of the membrane decreases. The change in the turbidity of the membrane was monitored by a UV-Vis-NIR …

Simultaneous Determination Of Nitrous Oxide And Ammonia For Measurement Of In-Situ Fluxes From Natural Ecosystems By Gas Chromatography With Headspace Autosampler And Electron Capture Detection, Richard Joseph Puk

Doctoral Dissertations

Anthropogenic disturbance of the soil nitrogen cycle by changes in nitrogen and carbon availability influences the production of N2O and NH 3 emissions to the atmosphere affecting the environment and human health. This dissertation presents a new method for automated gas chromatographic analysis of N2O and NH3 and quantifies fluxes from a salt marsh and tropical rain forest.

The automated system used single column gas chromatograhic separation on HayeSep Q and electron capture detection. Air (N2+O 2), N2O and NH3 are separated with retention times of 0.9, 1.7 and 2.15 minutes respectively. Samples were stored in headspace autosampler vials until …

Remote Optical Fiber Sensing Based On Reflectance Due To The Swelling Of Polymer Particles Produced By Dispersion Polymerization, Siobhan P. Milde

Doctoral Dissertations

Poly (4-vinyl pyridine) particles produced by dispersion polymerization were suspended in a hydrogel membrane and used for remote measurements employing fiber optic sensors. The refractive index of poly(4-vinyl pyridine) particles is higher than the refractive index of the hydrogel. At low pH, protonation of the poly(vinyl pyridine) causes the particles to swell reducing their refractive index and lowering membrane turbidity. The membrane response to pH was monitored using instrumentation originally that was constructed by Michael Civiello and was further developed in this work. A new hydrogel, HYPAN, was evaluated as the medium in which the particles are suspended. Methods for …

Swellable Polymer Substrates For Use In Magnetochemical And Optical Chemical Sensing, Stephen Arnold Doherty

Doctoral Dissertations

Lightly cross-linked, animated polymers that swell and shrink with changing pH were prepared and evaluated. At low pHs amine sites protonate causing charge to accumulate along the polymer backbone. The polymer then swells to maximize the charge separation. The swelling of the polymer causes a change in a magnetic or optical property that can be measured and related to pH.

Animated hydrogel membranes were prepared by copolymerizing dimethyl amino ethyl methacrylate(DMAEMA) with various comonomer hydrogels. Experiments were conducted to examine the effect of formulation on the ability of the hydrogel membrane to swell. Factors examined included cross-linker type, cross-linker concentration, …

Nitrated Poly(4 -Hydroxystyrene) Microspheres For Optical Ph And Potassium Ion Sensing Based On Turbidity Changes Accompanying Polymer Sweller, Hongming Wang

Doctoral Dissertations

Porous poly(4-acetoxystyrene) swellable microspheres with diameters approximately 1∼2 mum were prepared by seeded emulsion polymerization. Toluene was used as the porogenic solvent and divinylbenzene was used as the crosslinker. The seed particles with diameters approximately 0.5∼1 mum were prepared by dispersion polymerization without adding porogenic solvent and crosslinker. Functionality was introduced by two derivatization reactions, hydrolysis and nitration, to form nitrated poly(4-hydroxystyrene). These polymer microspheres swell at high pH due to the deprotonation of the hydroxyl group on the polymer backbone. Swelling is accompanied by an increase in water content which causes the polymer refractive index to decrease. These microspheres, …

A Non-Derivatization Approach To Hplc Fluorescence Detection For Some Important Amino Group-Containing Compounds Based On A Ligand Displacement Reaction, Min Yang

Doctoral Dissertations

Detection of some important amino group-containing compounds such as amino acids, aliphatic biogenic amines and aminoglycosides can present difficulties since these compounds do not possess strong fluorophores or chromophores. A novel indirect fluorescence detection method for these compounds has been developed, taking advantage of the fact they form complexes with Cu 2+ ions. The reaction between these compounds and a Cu(II)-L-tryptophan complex (Cu(L-Trp)2) in solution results in the displacement of L-Trp from the complex and an increase in L-Trp fluorescence, since the fluorescence of L-Trp is quenched in the Cu(II) complex. The increase in L-Trp fluorescence is taken as the …

Preparation And Characterization Of Derivatized Microparticles Immobilized In Hydrogel Membranes For Optical Chemical Sensing Based On Polymer Swelling, Eric William Miele

Doctoral Dissertations

Hydrogel membranes containing aminated microparticles have been investigated for reflectance based optical sensing. The membranes were evaluated by UV/Vis spectrophotometry, for potential use in a remote distributive fiber optic chemical sensor. This work describes efforts for improving the signal and decreasing the overall response time of the membranes. The microparticles were prepared by dispersion and seeded emulsion polymerization techniques. The microparticles were derivatized to introduce pH sensitivity. The hydrogel membranes containing swellable microparticles are turbid. Scattering occurs at the microparticle-hydrogel interface and is based on refractive index changes accompanying polymer swelling. The particles swell in response to hydrogen ion concentration, …

Sensors Forph Based On Swelling And Reflectivity Of Derivatized Polystyrene Beads And Membranes, Li Zhang

Doctoral Dissertations

Kraton-modified amine-derivatized poly(vinylbenzyl chloride) beads prepared by suspension polymerization are sensitive to pH. They swell in acid due to protonation of amine groups and shrink in base. Polymer swelling generates a measurable swelling signal that is related to the concentration of hydrogen ions in solution. The sensor responded to pH in the range from 6.0 to 10.0. Bead size, level of porogenic solvents and Kraton G1652 affected the magnitude of sensor response and response time.

Diethanolamine derivatized poly(VBC) membranes formulated with a small amount of Kraton G1652 reflect light. At low pH membranes turn clear. The observed optical change is …

Construction Of An X-Band Electron Nuclear Double Resonance Spectrometer And Partial Characterization Of An Iron Nitrosyl Complex Of Transferrin, Pamela Marie Proulx-Curry

Doctoral Dissertations

An X-band Electron Nuclear Double Resonance (ENDOR) spectrometer was constructed, tested at both room and liquid helium temperatures, and characterized at liquid helium temperature using a vanadyl-imidazole standard.

An iron nitrosyl complex of transferrin was studied. Three methods of generating nitric oxide gas were tested and resulted in no differences in product formation. The g-factors for the rhombic complex--prepared with and without carbonate addition to the buffer--were determined. For the complex prepared with carbonate g$\sb{\rm x}$ = 2.052, g$\sb{\rm y}$ = 2.028, and g$\sb{\rm z}$ = 2.013. For the complex prepared without addition of carbonate g$\sb{\rm x}$ = 2.051, g$\sb{\rm …

The Purification And Characterization Of An Extrapallial Fluid Protein From The Mollusc, Mytilus Edulis, Stephen Joseph Hattan

Doctoral Dissertations

Shell deposition within the bivalve mollusc Mytilus edulis is regulated by the macromolecules of the extrapallial fluid (EP fluid). These mineralization regulating macromolecules are thought to be responsible for the nucleation, growth regulation and growth cessation of the CaCO$\sb3$ mineral crystals that will inevitable constitute $\geq$95% of the mature shell.

This dissertation presents the results of the purification and characterization of the major EP fluid protein of the bivalve Mytilus edulis. The major EP fluid protein was determined to comprise 56% of the total fluid protein and to consist of 7.25% by weight carbohydrate. The protein was purified though a …

Formation And Fate Of Methyltin Compounds In The Great Bay Estuary (New Hampshire), Anne M. Falke

Doctoral Dissertations

Methyltin compounds (MeSn), which are not of anthropogenic origin, are common in estuaries, particularly in the marsh grass Spartina alterniflora. During the 1989 growing season, S. alterniflora leaves collected from three locations in the Great Bay Estuary were analyzed for MeSn and inorganic tin by hydride generation/atomic absorption spectrophotometry (HG-AAS). Total MeSn concentrations showed a sharp increase early in the season, reaching a maximum on May 23, then gradually decreased. Statistical calculations verified that date was a significant contributor to the observed variance, while location was not.

Two years later the seasonal study was expanded to include below ground portions …

Development Of Q-Band Epr/Endor Spectrometer And Epr/Endor Studies Of Dinitrosyl Iron Model Complexes, Wenge Wang

Doctoral Dissertations

A robust yet sensitive Q-band (35 GHz) cavity has been designed for routine variable temperature EPR (electron paramagnetic resonance) and ENDOR (electron nuclear double resonance) measurements down to 2 K. It consists of an aluminum or brass (plain, silver or gold plated) ribbon imbedded in a cylindrical epoxy or epoxy/quartz composite with a tunable piston at the bottom. The cavity has all the advantages of the traditional silver wire-wound cavity often used for Q-band measurements but is much more robust and easier to construct. The cavity suppresses degenerate resonant modes and minimizes wall eddy currents induced by field modulation. With …

Interactions Of Conjugated And Unconjugated Bile Salts With Model Phospholipid Membranes: Vibrational Spectroscopic Studies, Kimberly Ann Parthum

Doctoral Dissertations

Bile salts play important roles in digestion and the treatment of diseases. Few studies have been performed to determine, at the molecular level, the interactions of individual bile salt species with cellular membranes. Vibrational spectroscopy provides a noninvasive approach for characterizing the structural changes occurring within the lipid matrix due to their association with bioactive molecules. The frequency of the methylene stretching modes in the infrared spectra of the lipids comprising the membrane, as a function of temperature, yields information on the intra- and interchain order/disorder of the lipid matrix, the stability of the membrane, and the cooperativity between lipid …

Investigation Of Pd(A)(20)Pd(T)(20) In The Analytical Electrophoresis Apparatus, John Oliver Wooll

Doctoral Dissertations

The analytical electrophoresis apparatus (AEA) is capable of generating and monitoring the electrophoretic migration of macroions. The oligonucleotide pd(A)$\sb{20}\cdot$pd(T)$\sb{20}$ was use as a model to compound to evaluate the range and validity of AEA measurements under a variety of electric fields and solvent conditions. A broad range of electric fields yield consistent, reproducible values. The charge determination from different procedures, steady state electrophoresis (SSE) and electrophoretic mobility, have not been consolidated into a consistent theory but advancements in the scope and understanding of the AEA's potential have been made. The apparent charge from the AEA measured electrophoretic mobility, $\mu$, of …

Polymer Substrates For Optical Chemical Sensing, Michael Thomas Rooney

Doctoral Dissertations

Membranes for chemical sensing based on changes in light reflectance from amine-modified, porous, rubber-toughened poly(vinylbenzyl chloride-co-divinyl benzene) were prepared by bulk free radical polymerization. Xylene and dodecane were used as porogenic solvents and solutions were prepolymerized to viscous solutions prior to forming membranes. The crosslinked membranes are turbid and scatter light when unswollen. They swell in response to increases in hydrogen ion concentration, causing the membrane to reflect less light. Turbidity is ascribed mainly to scattering by water-filled macropores within the amine-functionalized membranes. Swelling decreases the refractive index of porous, hydrated polymers with 2% crosslinking by approximately 0.04 units, bringing …

Evaluation Of Polymer Coated Attenuated Total Reflection (Atr) Elements For The Analysis Of Organic Compounds In Aqueous Solution, Marc C. Ertan-Lamontagne

Doctoral Dissertations

A significant limitation of ATR/FTIR for the analysis of aqueous solutions is the relatively high bulk concentration of analyte required. One approach to improving the detection of an analyte is to incorporate a thin polymeric phase at the surface of the ATR element. The purpose of the polymeric phase is to extract the analyte of interest and concentrate it within the depth of penetration of the evanescent wave. Utilizing a very high molecular weight poly(vinyl chloride) phase the time necessary to reach equilibrium for a 0.05% (v/v) nitrobenzene in a 1.5% (w/v) methanol/water solution was over 60 minutes. A study …