Browsing by Author "Nikles, David E."
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Item The application of arylamines as redox auxiliaries, polar crystals, and organic semiconductors(University of Alabama Libraries, 2012) Gray, Lester Trummer; Blackstock, Silas C.; University of Alabama TuscaloosaArylamines and derivatives thereof have been developed for use in several applications. Among these include: the development of an arylamine moiety to act as a trigger and redox catalyst for an organic reaction, the use of a specific arylamine moiety as a synthon in the preparation of a series of polar organic crystalline materials, and a preliminary investigation of an arylamine salt as a potential organic semiconductor. The synthesis of novel norbornadiene (N) derivatives with appended redox-auxiliary (RA) units for use as switchable photoelectrochromic materials is reported. The photochemical and electrochemical properties are investigated by UV-vis spectroscopy, chemical actinometry, and cyclic voltammetry. The pendant RA functions as a stable redox unit capable of catalyzing the conversion of the N form to the quadricyclane (Q) form, releasing stored ring-strain energy as heat. Aside from demonstrating the principle of RA catalysis, the new N derivatives demonstrate possible utility as recyclable solar fuels or as photo-electrical switchable systems for informational or mechanical applications at the molecular level. A second project involving the preparation of a series of m-phenylenediamine derivatives which assemble (crystallize) preferentially with polar order is described. The crystal structures of these analogs have been elucidated by X-ray crystallography, and their crystalline properties explored by differential scanning calorimetry. Insight gained through this study has led to a greater understanding of the requirements for polar ordering of these molecules, allowing for the rational design of certain polar organic crystals derived from such structures. Finally, a preliminary study of the structure and properties of radical cation and dication salts of tetra(p-anisyl)-p-phenylenediamine (TAPD), which show promise for use as organic one-electron oxidants and as organic semiconductors, is presented. The preparation and characterization of TAPD salts is described. Their electrochemical properties have been explored by powder pellet I-V electrochemical measurements.Item Compositional Evolution During the Synthesis of FePt Nanoparticles(2008-09-25) Thompson, G. B.; Srivastava, Chandan; Nikles, David E.; University of Alabama TuscaloosaA series of FePt nanoparticles was synthesized by the thermal decomposition of iron pentacarbonyl and reduction in platinum acetylacetonate in phenyl ether solvent. A range of precursor molar ratios of 2, 1.5, and 1 between iron pentacarbonyl and platinum acetylacetonate was studied. After 30 min of reflux, the synthesis method produced a wide distribution in composition and size for the nanoparticles. Given 200 min of reflux, it was observed that the particle-to-particle composition and size narrowed, and the atomic ratio of Fe to Pt, for the majority of nanoparticles, approached the initial precursor molar ratios except for the molar ratio of 1. It is speculated that the compositional variability may be a result of the slow kinetics of iron pentacarbonyl’s decomposition in the reaction.Item Computational studies of atmospheric chemical processes, flexible catalysts, and of new materials for chemical hydrogen storage(University of Alabama Libraries, 2014) Garner, Edward B.; Dixon, David A.; University of Alabama TuscaloosaAdvanced electronic structure methods on high performance computers have been used to study new materials for technology applications and for atmospheric chemical processes of the halogens. Chapter 2 is focused on the thermodynamics of halogen oxides relevant to stratospheric ozone depletion chemistry. We calculated the thermodynamic properties of various key species to better understand what is happening in the atmosphere to help minimize our impact on the environment. This research is particularly important because of the lack of experimental data on these species. Chapter 3 is focused on the design of flexible catalysts for single electron transfer reactions using neutral Group 6B (Cr, Mo, W) pentacarbonyl complexes M(CO)5-L. It was found that various P-ligands such as phosphines, phosphalkenes, and phospha-quinomethanes can form radical cations and anions under redox conditions and that the radical site can be localized either on the metal or on the "non-innocent" ligand. More polar solutions will drive single electron transfer reactions to form the cationic and anionic metal based complexes with the appropriate oxidizing and reducing agents. Chapter 4 is the study of chemical hydrogen storage systems with a focus on borane amines. The goal was to develop economically viable and energy efficient processes to regenerate spent fuel formed by the release of hydrogen from ammonia borane. The thermodynamics for fuel regeneration processes of spent ammonia borane fuel, modeled as polyborazylene, were accurately predicted. A method using a modified Pictet-Trouton rule and calculated boiling points was used to estimate heats of formation of liquids for the prediction of the thermodynamics of reactions in the liquid phase. An effective tin catalyst with the potential to lower the cost for ammonia borane regeneration at an industrial scale was designed in collaboration with Los Alamos National Laboratory. However, it was found that at an industrial scale the process was limited due to the cost of transporting the tin catalyst around the spent fuel regeneration plant. Therefore, it was necessary to find a new method for regenerating spent ammonia borane fuel, and hydrazine was found to work very effectively in a one pot approach.Item Determining iron oxide nanoparticle heating efficiency and elucidating local nanoparticle temperature for application in agarose gel-based tumor model(Elsevier, 2016) Shah, Rhythm R.; Dombrowsky, Alexander R.; Paulson, Abigail L.; Johnson, Margaret P.; Nikles, David E.; Brazel, Christopher S.; University of Alabama TuscaloosaMagnetic iron oxide nanoparticles (MNPs) have been developed for magnetic fluid hyperthermia (MFH) cancer therapy, where cancer cells are treated through the heat generated by application of a high frequency magnetic field. This heat has also been proposed as a mechanism to trigger release of chemotherapy agents. In each of these cases, MNPs with optimal heating performance can be used to maximize therapeutic effect while minimizing the required dosage of MNPs. In this study, the heating efficiencies (or specific absorption rate, SAR) of two types of MNPs were evaluated experimentally and then predicted from their magnetic properties. MNPs were also incorporated in the core of poly(ethylene glycol-b-caprolactone) micelles, co-localized with rhodamine B fluorescent dye attached to polycaprolactone to monitor local, nanoscale temperatures during magnetic heating. Despite a relatively high SAR produced by these MNPs, no significant temperature rise beyond that observed in the bulk solution was measured by fluorescence in the core of the magnetic micelles. MNPs were also incorporated into a macro-scale agarose gel system that mimicked a tumor targeted by MNPs and surrounded by healthy tissues. The agarose-based tumor models showed that targeted MNPs can reach hyperthermia temperatures inside a tumor with a sufficient MNP concentration, while causing minimal temperature rise in the healthy tissue surrounding the tumor. (C) 2016 Elsevier B.V. All rights reserved.Item Development and characterization of high-performance functionalized membranes for antibody adsorption(University of Alabama Libraries, 2012) Shethji, Jayraj Kiritbhai; Ritchie, Stephen M. C.; University of Alabama TuscaloosaCapacity and selectivity are the major bottlenecks for the development of affinity membrane adsorbers for protein and antibody purification. The focus of this doctoral research is to develop polyethersulfone (PES) microfiltration (MF) membranes containing multiple highly selective poly(styrene-co-hydroxystyrene) grafts mimicking the key dipeptide Phe-132/Tyr-133 motif of ligand protein A to selectively adsorb immunoglobulin G (IgG) under convective flow conditions. This research work consists of two phases. In phase 1, homopolymer and block copolymer grafts were synthesized and characterized in the membrane pores using monomers styrene, ethoxystyrene, and chloromethylstyrene. 1H NMR characterization showed successful incorporation of the sequential stages of graft chemistry, including: polystyrene, poly(chloromethylstyrene), poly(ethoxystyrene), poly(styrene-b-ethoxystyrene), and poly(styrene-b-chloromethylstyrene). A study of monomer reactivity showed that chloromethylstyrene reacted approximately 1.3 times slower than styrene and ethoxystyrene during formation of homopolymers and block copolymers. The ion-exchange capacity of sulfonated functionalized membranes was 4.9 meq/g with as many as 125 repeat units per chain. In phase 2, PES MF membranes tailored with two different graft chemistries including poly(styrene-co-hydroxystyrene) and glycine functionalized poly((styrene-co-hydroxystyrene)-b-chloromethylstyrene) grafts were developed and tested for selective IgG adsorption. 1H NMR characterization confirmed membrane pore functionalization by poly(styrene-co-hydroxystyrene), chloromethylstyrene block addition, and subsequent glycine functionalization of the chloromethyl block. The dynamic binding capacity (DBC) for IgG was as high as 95 mg/ml, more than 9 times as compared to Sartobind® and Ultrabind® membranes and twice as compared to affinity resin. The DBC was independent of flow rate and there was no significant loss (<5%) in capacity at higher linear velocities (230 cm/h) indicating that the transport of IgG to the adsorptive sites is predominantly by convection. Bind and elute experiments showed that there was no significant loss of DBC over a period of five cycles and the average recovery of antibody was >94%. Competitive sorption using membranes containing negatively charged spacer arms showed that the membrane was ~11 times more selective for IgG than BSA. Additionally, the DBC was 22% higher (115 mg/ml) than without spacer arms indicating that the negatively charged spacer arms moved the grafted chains apart and improved the accessibility of IgG to the binding sites.Item Development of hydroxypropyl cellulose-filled poly(2-hydroxyethyl methacrylate) semi-interpenetrating networks for drug delivery(University of Alabama Libraries, 2010) Melnyczuk, John Michael; Brazel, Christopher S.; University of Alabama TuscaloosaCancer is the second leading cause of death in the United States of America and the National Cancer Institute has released a paper stating that the ideal cancer therapy should have an imaging, targeting, reporting, and therapeutic part. The overall project goal is to be able to create a delivery system that can be triggered externally to the body and can release an anticancer agent in a controlled manner. The current project deals specifically with using hydroxypropyl cellulose (HPC) filled poly(2-hydroxyethyl methacrylate) (PHEMA) (HFPG) hydrogel to cause a release of theophylline when the hydrogel is placed at a temperature above the lower critical solution temperature (LCST) of HPC (57 ºC) and to have no release at normal body temperature, 37 ºC. In a series of polymerization reactions, various compositions of hydroxypropyl cellulose (HPC) filled crosslinked PHEMA gels were synthesized by free radical polymerization. The LCST for different average molecular weights, M̅_n, of HPC were found to be 44.8 ºC ± 0.8, 48.7 ºC ± 0.3, and 46.2 ºC ± 0.7 for 80,000, 100,000, and 370,000 M̅_n HPC respectively. A change in concentration of HPC with a M̅_n 80,000 from 0.01 to 0.05 g/mL showed an increase in the LCST from 44.8 ºC ± 0.8 to 46.6 ºC ± 1.0. Changing the media from water to 0.65M sodium chloride change LCST from 46.6 ºC ± 1.0 to 35.4 ºC ± 2.3. The swelling study showed the mesh size was unaffected by synthesis temperature, analytical temperature, and HEMA to HPC ratio, indicating that HPC was pore-filling. Mechanical testing confirmed the results of the swelling study, in that there was no net change in the calculated mesh size with a change in analytical or synthesis temperature by either method. This study showed that HPC did change the mesh size with a change in the HEMA:HPC ratio. Dissolution testing for the release of theophylline from the HFPG hydrogel showed an increased release rate with an increase in analytical temperature was possible. The increase in synthesis temperature increased the release rate. It is shown that an increase in the HEMA:HPC ratio with a decrease in the diffusion coefficient. The HPC collapsed and evolved out of the HFPG and this effect could produce a higher diffusion. Further investigations should be conducted to test the effects of different initiators and crosslinking ratio's on the release of HFPG hydrogels.Item Drug binding characterization of CYPs utilizing CW and pulsed EPR(University of Alabama Libraries, 2015) Cuce, Alex Andrew; Bowman, Michael K.; University of Alabama TuscaloosaElectron paramagnetic resonance (EPR) methods have been used to study drug and ligand interactions with a super family of monooxygenase enzymes known as Cytochrome P450 (CYP). We examined the active-site of four different isoforms of CYPs before and after the addition of drug using EPR. Two of the CYPs studied, CYP3A4 and CYP2C9, play a major role in drug metabolism and the other two, CYP51B1 and CYP125A1, are attractive as therapeutic targets for the pathogen Mycobacterium tuberculosis. EPR has shown to be a quick and highly resolved method, in comparison to current methods such as crystal structure analysis and UV/Vis optical difference spectroscopy, to study CYPs ferric heme active-site before and after drugs bind, which could be very valuable in drug design. Chapter 2 examines pulsed EPR methods for studying the active-site in CYPs. The explanation of practical aspects of experimentation along with data processing provides the EPR background for studying ferric heme-containing enzymes enabling a researcher to extract highly resolved active-site information. The experimental EPR methods described in Chapter 2 are the methods used in Chapter 3 and 4. Chapter 3 examines the resting state active-site of all four isoforms which is structurally described as a single water molecule bound to the distal position of the ferric heme. CW EPR spectroscopy of the isoforms all gave different g-values and MCD showed that water ligands bind at different strengths depending on the CYP isoform which sheds light on substrate specificity in each isoform. An attempt was made at predicting nIR MCD transitions with the EPR parameters but results were unclear. Chapter 4 studied CYP2C9 and CYP125A1 in complex with drugs that had the same binding mode but different optical difference spectra. We showed that the low-spin complex between a drug-metabolizing CYP2C9 variant in complex with a drug PPT retains the water ligand seen in the resting state. Hydrogens from the axial water ligand are observed by pulsed EPR spectroscopy for both drug-free and drug-bound species showing that the drug does not displace the water ligand seen in the resting state. An 15N-label incorporated into PPT is .444 nm from the heme iron indicating that PPT is in the active-site. CYP125A1 gave the same EPR signatures seen for CYP2C9 and PPT along with an X-ray crystal structure of CYP125A1 in complex with LP10 showing a water-bridged complex. The same binding mode was seen in both complexes but optical difference spectra of CYP2C9 and PPT resemble ‘classic’ type II behavior while those of CYP125A1 and LP10 have reverse type I behavior, again providing direct evidence that optical difference spectra are not reliable for characterization of drug binding mode.Item Functional ionic liquids for use in pharmaceutical applications(University of Alabama Libraries, 2010) Hough, Whitney Lauren; Rogers, Robin D.; University of Alabama TuscaloosaFor years, the pharmaceutical industry has relied heavily on crystalline active pharmaceutical ingredients (APIs) that can be approved by the Federal Drug Administration (FDA) as neutral compounds, salts, or solvates of said neutral compounds and salts. Yet, the solid crystalline form can have unexpected and unfavorable effects on properties such as solubility, bioavailability, efficacy, etc., due to different polymorphic forms of the API. A drug can be present in multiple forms and interconvert between forms during isolation, manufacturing, storage, and transport of the end product. These unwelcome problems could be alleviated or even eliminated by the formation of a liquid drug, which possesses no crystal structure. Unfortunately, research in this area has been limited to solubilization of solid drugs into various drug delivery vehicles such as emulsions, suspensions, and liposomes. However, it is possible for a drug to crystallize from these vehicles during the manufacturing, storage, and transportation. Thus, a new method to liquefy pharmaceuticals, thereby reducing problems associated with the solid-state, is needed. A potential solution is the use of ionic liquids (IL), defined as salts that melt below 100 °C. Since ILs are salts it is possible to combine a pharmaceutical ion with any desired counter ion, thereby, providing a level of tunablity that is not possible with current techniques. This IL modular strategy was the basis for the research discussed here, in which APIs with known problems were combined with GRAS (generally regarded as safe) compounds or FDA-approved APIs, which resulted in ILs displaying dual biological functionality. This strategy was successful in producing a wide range of ILs, all containing at least one pharmaceutically active ion. The physical property set for these synthesized ILs was varied, as it is difficult to predict how two ionic organic compounds will interact. However, common trends regarding melting point depression, thermal stability, and solubility were determined. The most exciting results were exhibited during the biological testing, as several of the synthesized ILs demonstrated improved biological activity over the precursor ions. Additionally, the drug mechanism, at a cellular level, was found to be modified when contained within an IL. This indicates that ILs behavior differently in the body than simple halide containing salts. Overall, the obtained results signify that ILs can serve as pharmaceuticals, in which these liquid salts eliminate problems associated with the solid-state and displayed to synergistic physical and biological properties.Item Functionalized membranes for membrane chromatography(University of Alabama Libraries, 2011) Shethji, Jayraj Kiritbhai; Ritchie, Stephen M. C.; University of Alabama TuscaloosaThe focus of this thesis is synthesis and quantification of homopolymer and block copolymer grafts and understanding controlled polymer growth. The homopolymer and block copolymer grafts were synthesized through sequential cationic polymerization of styrene and substituted styrene monomers chloromethylstyrene (CMS) and 4-ethoxystyrene (ES) in the pores of microfiltration polyethersulfone (PES) membrane. Polymer growth aspects like kinetics of reaction, amount of monomer reacted, ion-exchange capacity (IEC), and graft length were studied with respect to initiator contact time and monomer feed concentration. Functionalization of the microfiltration membrane was achieved by a two step procedure. The first step was to introduce sulfonic acid initiator sites by mild sulfonation with 0.5N H2SO4. This was followed by cycling through each type of monomer solution (styrene and substituted styrenes). Successful introduction of homopolymer and block copolymer grafts was confirmed by material balances on the monomer/toluene permeate solutions. Analytical techniques used for quantification of polymer grafting include UV-Visible spectroscopy, gas chromatography and atomic absorption. The functionalized membrane showed a steep decrease in membrane permeability compared to the raw membrane indicating the presence of polymeric chains in the membrane flow path. Functionalized membranes prepared by this method have as many as 125 repeat units per chain. Given the initiator concentration, this equates to an IEC of 4.9 meq/g, indicating high dynamic and equilibrium binding capacity. Pseudo-first-order kinetic expression correlated well with the experimental data for each monomer reacted. At lower initiator surface density, graft length and IEC were impacted by both monomer feed concentration and initiator contact time. However, for higher initiator surface density, monomer feed concentration parameter dominates. Block copolymer formation is the first step to synthesizing an analog of the phenylalanine/tyrosine dipeptide structure in protein A, which is shown in literature for selective adsorption of immunoglobulin G (IgG). This work will lead to further development of functionalized membranes as membrane adsorbers for high throughput production of monoclonal antibodies for new cancer therapies. In addition, it will lead to discoveries in sequential polymerization to generate customized structures and design of synthetic affinity ligands.Item Impact of magnetic field parameters and iron oxide nanoparticle properties on heat generation for use in magnetic hyperthermia(Elsevier, 2015) Shah, Rhythm R.; Davis, Todd P.; Gover, Amanda L.; Nikles, David E.; Brazel, Christopher S.; University of Alabama TuscaloosaHeating of nanoparticles (NPs) using an AC magnetic field depends on several factors, and optimization of these parameters can improve the efficiency of heat generation for effective cancer therapy while administering a low NP treatment dose. This study investigated magnetic field strength and frequency, NP size, NP concentration, and solution viscosity as important parameters that impact the heating efficiency of iron oxide NPs with magnetite (Fe3O4) and maghemite (gamma-Fe2O3) crystal structures. Heating efficiencies were determined for each experimental setting, with specific absorption rates (SARs) ranging from 3.7 to 325.9 W/g Fe. Magnetic heating was conducted on iron oxide NPs synthesized in our laboratories (with average core sizes of 8, 11, 13, and 18 nm), as well as commercially-available iron oxides (with average core sizes of 8, 9, and 16 nm). The experimental magnetic coil system made it possible to isolate the effect of magnetic field parameters and independently study the effect on heat generation. The highest SAR values were found for the 18 am synthesized particles and the maghemite nanopowder. Magnetic field strengths were applied in the range of 15.1-47.7 kA/m, with field frequencies ranging from 123 to 430 kHz. The best heating was observed for the highest field strengths and frequencies tested, with results following trends predicted by the Rosensweig equation. An increase in solution viscosity led to lower heating rates in nanoparticle solutions, which can have significant implications for the application of magnetic fluid hyperthermia in vivo. (C) 2015 Elsevier B.V. All rights reserved.Item In-situ investigation and mitigation of carbon support corrosion of cathode catalyst in PEM fuel cells(University of Alabama Libraries, 2010) Li, Wei; Lane, Alan M.; University of Alabama TuscaloosaCarbon support corrosion (CSC) is one of the key factors causing cathode electrocatalyst (Pt/C) degradation in proton exchange membrane fuel cells (PEMFC). It is electrochemical oxidation and thus needs to be investigated in-situ with potential imposed. CSC was characterized in-situ and correlated to the Pt redox reactions and Pt-catalyzed oxygen reduction reaction (ORR) by the differential electrochemical mass spectrometry (DEMS) spectra of cathode exhaust gases, CO₂, H₂ and O₂, from a PEMFC fed with humidified H₂ and He to the anode and cathode respectively. Furthermore, the catalytic effects on CSC from different oxidation states of Pt were indicated. To determine the oxygen sources and pathways of CSC, oxygen was isotopically labeled by replacing regular water with oxygen-18 (¹⁸O) enriched water (H₂¹⁸O, 98%) in DEMS, denoted as ¹⁸O-DEMS. 18O-DEMS spectra of the cathode exhaust gases O₂, O¹⁸O, ¹⁸O₂, CO₂, CO¹⁸O and C¹⁸O₂ during cyclic voltammetry and chronoamperometry were analyzed to verify that water is the main direct oxygen source for CSC. Moreover, water reacts with carbon to produce at least three types of carbon surface oxides, which are further electrochemically oxidized with water to produce CO₂ in different potential ranges. After accelerated testing of cathode catalyst degradation in PEMFC using potential cycling between 100-1400 mV at the rate of 400 mV/s, the changes of mass spectra of CO₂, H₂ and O₂ over time showed that the CSC decreases as Pt electrochemically active surface area (ECSA) decreases, i.e. catalyst activity decreases, but the membrane does not degrade significantly in gas permeability. A hypothesis is proposed here that Au nanoparticles (NPs) added to a carbon-supported Pt (Pt/C) catalyst can mitigate the Pt catalytic effects on CSC by suppressing the Pt oxidation. Several methods were tried to synthesize Pt/C (20 wt% Pt) and bimetallic AuPt/C (20 wt% Pt, 5 wt% Au) catalysts including deposition-precipitation, two phase liquid-liquid colloidal, polyol, microwave-assisted polyol, and surface redox methods. TEM pictures showed that the EG method (polyol method using ethylene glycol), microwave-assisted EG method, and colloidal method produced Pt/C catalysts with high dispersion and narrow particle size distribution of Pt NPs uniformly loaded on the carbon support. Au NPs with high dispersion and narrow particle size distribution can be made only by the colloidal method. AuPt/C catalysts were synthesized by two methods: physically by mixing Au NPs prepared by the colloidal method on Pt/C prepared by the EG method, and chemically by surface redox reactions of a Au precursor on Pt NPs prepared by the EG method and then loaded on the carbon support (denoted as AuPtC-EG-SR). The existence of Au on Pt/C was confirmed by EDX and by a larger ring current from ORR experiment using a rotating ring-disk electrode. Three membrane electrode assemblies (MEA) with commercial Etek Pt/C and those two types of AuPt/C catalysts as cathode catalyst respectively were fabricated for CSC comparison. Larger ECSA but less CO₂ intensity of the MEA with a AuPtC-EG-SR cathode than those of the MEA with Etek Pt/C gives preliminary confirmation of the hypothesis.Item Isolation of soft donor complexes of d- and f-block metals using ionic liquids(University of Alabama Libraries, 2015) Kelley, Steven Paul; Rogers, Robin D.; University of Alabama TuscaloosaIonic liquids (ILs) are alternatives to conventional molecular liquids or high-melting salts which can be used to gain new insight into long-standing scientific questions. The ability to access a compositionally variable, purely ionic liquid environment in an IL is particularly significant in coordination chemistry, which often involves the manipulation of an ionic metal-ligand bond. This study aims to demonstrate the potential utility of ILs in coordination chemistry by using them to access unusual metal complexes with soft Lewis bases, especially those of f-elements. Such complexes are particularly important use in studying the nature of f-element chemical bonding and the interactions involved in their isolation, propagation through the environment, or distribution in living organisms. A number of strategies using ILs and systems derived from ILs are explored. In reactions of dicyanamide-containing ILs with uranyl salts, the use of an IL as a source of nitrogen-containing soft donor ligands led to the isolation of uranyl dicyanamide complexes through substitution of oxygen-donor ligands by IL anions. By reacting actinide nitrate hydrates with a nitrate-containing IL, anhydrous complexes were obtained which could be used as precursors for the formation of nitrogen-donor adducts. The permanent elimination of oxygen-containing anions from a metal salt was explored through reactions of an acidic azole with metal acetate salts, although this approach was found to be limited by side reactions. The use of a partially anionic sulfur ligand derived from an IL led to the formation of uranyl and neodymium sulfur-donor complexes. The scope of nitrogen-containing ligands which could be incorporated into an IL was expanded by demonstrating the use of combinations of acidic and basic azoles as liquids for nitrogen donor coordination chemistry. These platforms have considerable room for expansion beyond the metal complexes already isolated. Future studies will expand the range of soft donors incorporated in the IL beyond nitrogen. Combinations of these strategies will also be explored with the aim of producing entirely soft-donor ligated complexes from readily available starting materials.Item The localization and behavior of fluorescently tagged magnetic nanoparticles in biological systems(University of Alabama Libraries, 2009) Sewell, Mary Kathryn; Brazel, Christopher S.; University of Alabama TuscaloosaA novel combination cancer therapy platform incorporating chemotherapy and hyperthermia is proposed. Magnetic nanoparticles are included as a way to achieve the hyperthermia treatment, as well as for use as a platform for targeting, imaging, or other therapeutic moieties. Cobalt ferrite (CoFe₂O₄) magnetic nanoparticles (MNPs) were synthesized and tagged with the fluorescent dye rhodamine for tracking in biological systems. The MNP solutions were characterized to determine average diameters of the nanoparticles. Results indicate that sample age, solvent, and concentration can affect the diameters of MNP agglomerates as measured by dynamic light scattering. Older and more concentrated samples, which also tend to be less stable, showed larger MNP sizes than newer and less concentrated samples. Rhodamine-tagged MNPs showed smaller diameters than untagged MNPs at the same concentrations. For MNP in HeLa cell localization studies, the rhodamine-tagged MNPs showed uptake and localization in the cytoplasm of the cells. Partition coefficients, or the ratios of MNP concentrations inside the cells to the extracellular concentration, were shown to increase during the first 6 h of incubation time, with values reaching as high as 3.805, indicating favorable uptake of the MNPs. After 24 h, a smaller ratio of internalized MNPs was seen due to cytotoxic properties of the high concentration of MNPs used in those experiments. Toxicity studies showed that at concentrations below approximately 0.025 mg/mL, both rhodamine-tagged and untagged CoFe₂O₄ MNPs have little effect on cell viability. MNP localization and toxicity studies were also carried out on a model organism, C. elegans worms, with an indication that rhodamine-tagged CoFe₂O₄ MNPs were non-toxic to worms over a period of 12 days. Localization of the MNPs within the worms was inconclusive due to indistinguishable autofluorescence of the C. elegans and the rhodamine fluorescence of tagged MNPs. Further work is needed to characterize the CoFe₂O₄ MNPs for use in the cancer treatment platform.Item Magnetic heating of Fe3O4 nanoparticles and magnetic micelles for a magnetothermally-triggered drug delivery system for cancer therapy(University of Alabama Libraries, 2012) Bennett, James Brandon; Brazel, Christopher S.; University of Alabama TuscaloosaMagnetic nanoparticles, MNPs, combined with stimuli-responsive polymers show potential to enhance the efficacy of cancer therapy in multifunctional nanoscale drug delivery systems. This project investigates the use of iron oxide nanoparticles (magnetite) to generate heat, via an applied magnetic field, to stimulate drug release of doxorubicin from an RGD-peptide targeted thermo-sensitive poly (ethylene glycol)-b-poly (caprolactone) micelle. Fe_3 O_4; nanoparticles custom synthesized at UA show the ability to heat to temperatures adequate for melting a semi-crystalline poly (caprolactone) micelle core. Investigations into parameters effecting magnetic heating of Fe_3 O_4 included studying the effects of magnetic field strength, H, and frequency, f. The results showed magnetic heating of the MNPs could induce hyperthermic temperatures. Specific absorption rates (SAR) for the MNPs were in the range of previously reported magnetite SARs, and followed the relationship with magnetic field strength predicted by the Rosensweig equation. The internal energy change in magnetic micelles was larger than that observed for MNPs in hexane when heated by an AC magnetic field. Drug release studies using triamterene- and doxorubicin- loaded micelles show a temperature-dependent acceleration of drug release at temperatures above 42 °C, the melting point of poly (caprolactone), as well as the possibility of magnetic induction hyperthermia-activated release.Item Magnetic Heating of Iron Oxide Nanoparticles and Magnetic Micelles for Cancer Therapy(IEEE, 2013) Glover, Amanda L.; Bennett, James B.; Pritchett, Jeremy S.; Nikles, Sarah M.; Nikles, David E.; Nikles, Jacqueline A.; Brazel, Christopher S.; University of Alabama Tuscaloosa; University of Alabama BirminghamThe inclusion of magnetic nanoparticles into block copolymer micelles was studied towards the development of a targeted, magnetically triggered drug delivery system for cancer therapy. Herein, we report the synthesis of magnetic nanoparticles and poly( ethylene glycol-b-caprolactone) block copolymers, and experimental verification of magnetic heating of the nanoparticles, self-assembly of the block copolymers to form magnetic micelles, and thermally-enhanced drug release. The semicrystalline core of the micelles melted at temperatures just above physiological conditions, indicating that they could be used to release a chemotherapy agent from a thermoresponsive polymer system. The magnetic nanoparticles were shown to heat effectively in high frequency magnetic fields ranging from 30-70 kA/m. Magnetic micelles also showed heating properties, that when combined with a chemotherapeutic agent and a targeting ligand could be developed for localized, triggered drug delivery. During the magnetic heating experiments, a time lag was observed in the temperature profile for magnetic micelles, likely due to the heat of fusion of melting of polycaprolactone micelle cores before bulk solution temperatures increased. Doxorubicin, incorporated into the micelles, released faster when the micelles were heated above the core melting point.Item Magnetic properties of nano-composite particles(University of Alabama Libraries, 2015) Xu, Xia; Lane, Alan M.; University of Alabama TuscaloosaChemical synthesis routes for hollow spherical BaFe12O19, hollow mesoporous spherical BaFe12O19, worm-shape BaFe12O19 and FeCo particles were developed. These structured particles have great potentials for the applications including magnetic recording medium, catalyst support, and energy storage. Magnetically exchange coupled hard/soft SrFe12O19/FeCo and MnBi/FeCo composites were synthesized through a newly proposed process of magnetic self-assembly. These exchange coupled composites can be potentially used as rare-earth free permanent magnets. Hollow spherical BaFe12O19 particles (shell thickness ~5 nm) were synthesized from eth-ylene glycol assisted spray pyrolysis. Hollow mesoporous spherical BaFe12O19 particles (shell thickness ~100 nm) were synthesized from ethanol assisted spray pyrolysis, followed by alkaline ethylene glycol etching at 185 oC. An α-Fe2O3 and BaCO3 nanoparticle mixture was synthesized with reverse microemulsion, followed by annealing at 900 oC for 2 hours to get worm-shape BaFe12O19 particles, which consisted of 3-7 stacked hexagonal plates. FeCo nanoparticles were synthesized by reducing FeCl2 and CoCl2 in diphenyl ether with n-butyllithium at 200 oC in an inert gas environment. The surfactant of oleic acid was used in the synthesis to make particles well dispersed in nonpolar solvents (such as hexane). SrFe12O19/FeCo core/shell particles were prepared through a magnetic self-assembly process. The as-synthesized soft FeCo nanoparticles were magnetically attracted by hard SrFe12O19 parti-cles, forming a SrFe12O19/FeCo core/shell structure. The magnetic self-assembly mechanism was confirmed by applying alternating-current demagnetization to the core/shell particles, which re-sulted in a separation of SrFe12O19 and FeCo particles. MnBi/FeCo composites were synthesized, and the exchange coupling between MnBi and FeCo phases was demonstrated by smooth magnetic hysteresis loop of MnBi/FeCo composites. The thermal stability of MnBi/FeCo composites was investigated by annealing at 250 oC for 2 hours in N2 environment. The results showed that FeCo nanoparticles were sintered and agglom-erated during the annealing, and exchange coupling between MnBi and FeCo was destroyed. Future work was proposed in three aspects: chemical synthesis of MnBi particles; decreas-ing the particle size of MnBi particles and maintaining their stability; improving the thermal sta-bility of MnBi/FeCo composites.Item A magnetically triggered, targeted therapeutic drug delivery system from polymer micelles(University of Alabama Libraries, 2014) Glover, Amanda Louise; Nikles, David E.; University of Alabama TuscaloosaCurrent chemotherapeutic treatment options rely on delivering high doses of toxic chemicals to a patient in the hopes that some of the drug will kill the cancer. This method of treatment leads to side effects ranging from hair loss to healthy cell mutation. To combat the potential for these side effects a method of delivery for therapeutics has been developed from polymer micelles housing the drug that specifically targets and binds to cancer cells. Not only can the cancer cells be targeted directly, thus reducing the detrimental side effects, but temporal control of therapeutic delivery can be achieved by a magnetically triggered mechanism. In the semi-crystalline core of the micelles, magnetic nanoparticles are housed with the therapeutic drug. Once an alternating current (ac) magnetic field is applied to the micelles, the magnetic particles heat, allowing the cores to melt, which allows the drug to diffuse from the cores of the micelles.Item Medusa particles: a magnetically triggered drug delivery system consisting of peg-pcl diblock polymer brushes bound to the surface of single crystal magnetite nanoparticles(University of Alabama Libraries, 2016) McCormick, Benjamin Joseph; Nikles, David E.; University of Alabama TuscaloosaCurrent cancer chemotherapy treatment involves intravenous administration of highly toxic drugs relying on the strategy that some of the chemotherapy agent will reach the site of cancer and effectively kill those cells. This method leads to mutation and damage of healthy cells, which can manifest into side effects including fatigue, alopecia, and death. To combat these side effects and to target cancer cells preferentially, we aimed to develop a drug delivery system in which chemotherapy agents, such as doxorubicin, are entrapped within a semi-crystalline polymer shell covalently attached to the surface of magnetic nanoparticles. Not only could these “medusa particles” be directed to specific sites of cancerous tissue using targeting ligands attached to an external polymer corona, but their release of drug could also be temporally controlled by a magnetically triggered thermal induction mechanism. Once the particles reach the sites of cancer, an external radio frequency alternating current magnetic field would be applied to heat the nanoparticles causing the polymer shell to melt and allowing the drug to diffuse out of the core. This mechanism could have extensive biomedical applications due to the wide variety of targeting ligands and drugs one could utilize in the drug delivery system. In this thesis, we have demonstrated synthesis of magnetite nanoparticles verified by the x-ray photoelectron spectroscopy in the Fe 2p binding energy region, and were determined to be 11 nm in diameter as seen by transmission electron microscopy. Doxorubicin was successfully loaded into medusa particles at about 2-3% by total weight on average. Magnetically triggered release of doxorubicin from medusa particles was demonstrated and monitored using UV-Vis spectroscopy, electrochemical methods including linear sweep and differential pulse voltammetry, and cell studies involving CHO-K1 cells.Item Nanocrystals and thin films of oxide and chalcogenide spinels for spintronic applications(University of Alabama Libraries, 2010) Wang, Yu-Hsiang; Gupta, Arunava; University of Alabama TuscaloosaSpin-based transport in semiconductor systems has been proposed as the foundation of a new class of spintronic devices. For the practical realization of such devices it is important to identify magnetic materials with diverse electronic transport properties (metallic, semiconducting, insulating) and sufficiently high Curie temperature (T_C ) that can be readily integrated with standard semiconductors. Promising classes of materials for this purpose are the magnetic spinel oxides and chalcogenides. Some of these spinel-based materials are also attractive for biomedical applications. The facile solution-based synthesis of monodisperse nanocrystals of a wide variety of magnetic ferrites and nanocrystals of the chalcospinel CuCr_2 Se_4 , along with their structural and magnetic properties, is presented in the first section of the dissertation. The following section presents a theoretical investigation of the electronic band structure of two quaternary chalcospinel systems, Cd_x Cu_1-x Cr_2 Se_4 and Cd_x Cu_1-x Cr_2 S_4 , and also a number of anion-substituted Cr-based chalcospinels. A wide range of half-metal compositions are predicted both for the cation and anion substituted chalcospinels. The synthesis of spinels has been expanded to the growth of ferrites films using the direct liquid injection chemical vapor deposition (DLI-CVD) technique, which is detailed in the last section of the dissertation. High quality epitaxial NiFe_2 O_4 films have been grown using this technique with the magnetic properties of the films being comparable to those observed in the bulk, even for films grown at a high deposition rate. The growth of other thin film ferrites, such as lithium ferrite and barium hexaferrite, which are useful for higher frequency microwave applications are being investigated. The eventual goal is to use extend the DLI-CVD technique for the synthesis of chalcospinels films - in particular those predicted to be half-metallic - which have the potential for a variety of applications in spintronic devices.Item New materials for optical sensing of explosives copolymers containing 2-vinyl-4,6-diamino-1,3,5-triazine and co-crystals of electron rich aromatic molecules and 1,3-dinitrobenzene(University of Alabama Libraries, 2013) McNeil, Steven Keith; Nikles, David E.; University of Alabama TuscaloosaThis dissertation focuses on the development of electron rich polymers with an affinity for nitroaromatics. Thin polymer films of the electron rich polymers could be applied in an optical waveguide sensor to detect nitroaromatics by changes in the optical properties of the polymer thin films. Charge transfer complexes between electron rich aromatic reagents and electron deficient nitroaromatics were produced providing an understanding of the intermolecular interactions between the electron donor and electron acceptor. Electron rich copolymers were synthesized with 2-vinyl-4,6-diamino-1,3,5-triazine (VDAT) using a published literature procedure. The polymerization procedure was extended to a variety of electron rich monomers, resulting in the production of a number of electron rich copolymers. Thin films of the copolymers were spin coated and their optical properties were characterized by spectroscopic ellipsometry before and after exposure to a nitroaromatic vapor. The exposure to the nitroaromatic vapor allowed the formation of complexes with the electron rich copolymers and the nitroaromatic molecules, creating a change in the optical properties of the polymer films. This refractive index change after exposure to a nitroaromatic demonstrated the possibility of these films to be applied in an optical waveguide sensor for explosive detection. Co-crystals were grown between electron rich donors and the electron deficient 1,3-dinitrobenzene by the slow evaporation method. When the electron donor solution and electron acceptor solution were combined in a crystallization dish, significant color changes were observed. The interaction between the electron donor and electron acceptor were characterized using analytical techniques.