The design and development of nanoparticles is of great interest in the current energy and electronic industry. However, based on the current materials available the production cost can be high with insignificant magnetic and mechanical properties. Specifically, rare-earth magnetic materials composed of neodymium and samarium are known for their high magnetic performance, however, due to the cost of development there is a need to develop a versatile and cost effective material. Alternatively, cobalt carbide nanomaterials have shown to be a promising alternative for rare-earth free magnets as they exhibit comparable properties as hexaferrite magnetic materials. The primary goal of this dissertation focuses on the development of nanoparticles for permeant magnetic, and magnetic refrigeration applications. The first part of this work focuses on the synthesis of cobalt carbide (CoxC, x=2,3) nanoparticles using a novel polyol synthesis method by introducing a small amount of Ru, Cu, or Au as nucleating agent. It was found that the morphology and magnetic properties of the as-synthesized CoxC nanoparticles change as a result of directional growth of nanoparticles using nucleating agents. Needle-like particle morphology ranges from 20-50 nm in width and as long as 1 µm in length were synthesized using Ru as nucleating agent. These particles exhibit magnetization saturation of 33.5 emu/g with a coercivity of 2870 Oe and a maximum energy product 1.92 MGOe (BHmax) observed. Particle morphology is a critical aspect in the development of magnetic nanoparticles as anisotropic particles have shown increased coercivity and magnetic properties. These CoxC nanomaterials have a higher maximum energy product compared to previous work providing further insight into the development of non-rare earth magnetic material. The second part of this dissertation work focuses on the sol-gel synthesis of perovskite LaCaMnO3 (LCMO) nanomaterials. In this process, various chain lengths of polyethylene glycol (PEG) was added into a solution consisting of La, Ca, and Mn salts. The solution was left for the gelation process, and high temperature sintering to obtain the final product. By varying the polymer chain of the PEG, the size of the as synthesized LaCaMnO3 nanomaterials were altered. The as-synthesized LCMO nanomaterials have shown a maximum change in magnetic entropy (-ΔSM) was found to be 19.3 Jkg-1K-1 at 278 K for a field change of 0-3 T and 8.7 Jkg-1K-1 for a field change of 0-1 T. This is a significant improvement in comparison to current literature of the material suggesting that this is a promising alternative to Gd materials that is prone to oxidation. With additional development, LCMO or related maganites could lead to application in commercial technologies.

Lubricants play an integral role in the operation of several technologies and in biology also, ranging from moving parts in machinery to the biolubrication of artificial joints. We have found that a colloidal dispersion consisting of easily synthesized highly spherical and uniform graphitic carbon particles results in a very efficient water based "green" and environmentally sustainable lubricant with very low friction coefficients and excellent surface wear protection. These particles use a rolling mechanism similar to nano --or microscale ball bearing under confinement. The effect of particle size on lubrication will be introduced and discussed. Additionally, carbon from sugars and carbohydrates, considered as "green precursors" because of their abundance in nature, have been favored for their low environmental impact and cost when compared to traditional oil based lubricants. The second part of my dissertation presents the fabrication and design of a novel bidirectional membrane device to assist child delivery in resource-limited settings. Approximately one third of pregnancies are delivered by one out of three possible operative methods: vacuum extraction, forceps operation, or caesarean section. Using these traditional devices or alternative methods, the risk of injuring to the mother and the fetus is elevated tremendously in the wake of poor training. Here, I present a polymer-based membrane, which will provide ultra-low friction thus facilitating child delivery but also have the ability to provide high friction when needed for child extraction. Specifically, the friction properties between polydimethylsiloxane (PDMS) and a borosilicate surface were studied using different lubricating media. The dynamics of the anisotropic surface morphology will be discussed and applied to this novel membranous device.

Dans le cadre du projet MultiFun par lequel cette thèse a été financée, nous avons travaillé en collaboration avec des équipes européennes de synthèse chimique pour proposer des nanoparticules d'oxydes de fer dédiées à la détection et au traitement du cancer par hyperthermie magnétique. Habituellement, l'efficacité des nanoparticules est déterminée par la valeur du SAR (Specific Absoption Rate, en W/g), mesuré par élévation de température. Nous avons développé un banc permettant la mesure de cycles d'hystérésis dans les mêmes gammes d'amplitude et de fréquence de champs magnétiques que celles utilisées habituellement en hyperthermie magnétique. Le cycle d'hystérésis fourni plus d'informations sur l'échantillon et permet par exemple d'évaluer l'importance des interactions inter-particulaires. Le projet MultiFun prévoyait également l'étude du traitement in vivo. Le LPCNO a donc développé un inducteur adapté aux expériences sur le petit animal (souris, rats). Cet électroaimant refroidit à l'air a un entrefer de 3 cm et fonctionne à un champ de 23 mT pour des temps de traitements d'une heure. Nous avons également collaboré avec le Laboratoire de Réceptologie et Ciblage Thérapeutique en Cancérologie pour effectuer des expériences d'hyperthermie magnétique in vitro au moyen de nanoparticules fonctionnalisées puis internalisées de manière spécifique dans les lysosomes. L'application d'un champ magnétique haute fréquence aux cellules contenant ces nanoparticules induit de forts pourcentages de mort cellulaire (principalement par voies apoptotique). Dans ces travaux, les nanoparticules ont de faibles SAR et sont présentes en faibles quantités dans les cellules, ce qui n'engendre pas d'élévations de températures mesurables. L'efficacité du traitement dans ces conditions pose nombre de questions quant aux mécanismes réels entrainant la mort de la cellule. Pour tenter de répondre à ces questions, nous avons conçu un système permettant d'appliquer des champs magnétiques hautes fréquences in vitro sous un microscope confocal à fluorescence couramment utilisé pour suivre des mécanismes intracellulaire à l'aide de fluorochromes. On introduit un électroaimant miniaturisé (largeur d'entrefer ≈ 400 μm) directement dans une boite de culture cellulaire. On génère ainsi un champ d'environ 60 mT à 300 kHz. Cette méthode nous permet d'observer les cellules et leurs organites durant le temps de traitement. Les niveaux de mort cellulaire atteints ici sont équivalents aux expériences précédentes, et valident ainsi l'utilisation de cet inducteur à entrefer réduit. Pour l'heure, nous avons quantifié l'apparition en temps réel des ROS (Reactive Oxygen Species) dans la cellule lors de l'application du champ. Nous avons également mis en lumière la perméabilisation lysosomale, qui peut engendrer la libération d'agents de mort cellulaires. Enfin cet outil permettra de continuer les recherches de mécanismes intracellulaires pour des échantillons soumis à un champ magnétique extérieur. Les nanoparticules soumises à un champ magnétique alternatif peuvent également être utilisées comme catalyseurs de réactions chimiques. Nous avons utilisé les nanoparticules synthétisées au LPCNO comme catalyseurs de la réaction Fischer-Tropsch. Ce procédé permet de produire industriellement des hydrocarbures à partir de monoxyde de carbone et de dihydrogène. Des caractérisations poussées des propriétés structurales, magnétiques, d'échauffement et de catalyse ont été menées sur des nanoparticules possédant un cœur de fer recouvert d'un métal catalytique (ruthénium ou cobalt). La preuve que ces nanoparticules peuvent catalyser la réaction de Fischer-Tropsch lorsqu'elles sont soumises à un champ magnétique haute-fréquence a été établie, et une bonne corrélation entre leur puissance de chauffe et leur activité catalytique a été montrée. / As partners of Multifun by which this thesis was funded, we have worked with European groups of chemists to provide iron oxide nanoparticles dedicated to the detection and treatment of cancer by magnetic hyperthermia. Usually, the nanoparticles efficiency is determined by the SAR value (Specific Absoption Rate, in W / g), measured by a calorimetric method. We have developed a device for measuring hysteresis loops at the same amplitude and frequency range of magnetic fields than those usually used in magnetic hyperthermia. Hysteresis loops provide more information about the samples and allows for example to assess the importance of inter-particle interactions. Multifun project also included the study of in vivo treatments. LPCNO has developed an inductor suitable for experiments on small animals (mice, rats). The electromagnet is air-cooled, displays a gap of 3 cm and operates at a field of 23 mT during one hour. We also worked with the Laboratoire de Réceptologie et Ciblage Thérapeutique en Cancérologie, Toulouse, to perform in vitro magnetic hyperthermia experiments using functionalized nanoparticles specifically internalized into lysosomes. The application of a high frequency magnetic field to the cells containing these nanoparticles induces a significant cell death (mainly apoptotic pathways). In these studies, the nanoparticles have low SAR, and are present in small quantities in the cells. Thus no temperature rise is measured during the experiments. The efficacy of treatment in these conditions poses many questions about the actual mechanisms at the origin of cell death. To try to answer these questions, we have designed a setup permitting to apply high frequency magnetic fields under a confocal fluorescence microscope; the latter is commonly used to monitor intracellular mechanisms with fluorochromes. We introduce a miniaturized solenoid (gap width ≈ 400 µm) directly into a cell culture box. This generates a field of approximately 60 mT at 300 kHz. This method allows us to observe the cells and their organelles during the time of treatment. Infected cell death levels here are equivalent to the previous experiments, which thus validates the use of this reduced gap inductor. For now, we quantified the appearance of ROS (Reactive Oxygen Species) in real time in the cell during the application of the field. We also evidenced the lysosomal permeabilization, which can cause the release of cellular death agents. Finally this tool will serve to continue research on intracellular mechanisms in cells inside an external high-frequency magnetic field. Nanoparticles subjected to an alternating magnetic field can also be used as catalysts of chemical reactions. We used the nanoparticles synthesized LPCNO as catalysts for the Fischer-Tropsch reaction. This process allows the industrial production of hydrocarbons from carbon monoxide and hydrogen gas. Extensive characterizations of structural, magnetic, heating and catalysis properties were carried out on nanoparticles with an iron core coated with a catalytic metal (ruthenium or cobalt). Evidence that these nanoparticles catalyze the Fischer-Tropsch synthesis when subjected to a high-frequency magnetic field has been established, and a good correlation between their heating power and their catalytic activity has been shown.

This work strived to increase knowledge of assessing airborne nanoparticles in the workplace by characterizing nanoparticle concentrations in a workplace using direct-reading instruments, evaluating a DC2000CE diffusion charger, and the creation of a personal diffusion battery (pDB). Direct-reading instruments were used with aerosol mapping and task monitoring to evaluate airborne nanoparticle concentrations in an apparel company that produces waterproof jackets composed of polytetrafluoroethylene membrane laminated fabric. Jacket production required that sewn seams be sealed with waterproof tape applied with hot air (600°C). Particle number concentrations were greater in the sewing and sealing areas than the office area while respirable mass was negligible throughout the facility. The breathing zone particle number concentrations of the workers who sealed the sewn seams were highly variable and significantly greater when sealing seams than when conducting other tasks (p<0.0001). The effectiveness of the canopy hoods used to ventilate sealing operations was poor. These measurements support the idea that work places were hot processes are conducted may have substantially greater concentrations of airborne nanoparticles than background measurements even with control measures in place. Laboratory tests were conducted to evaluate a commercially available diffusion charger, the DC2000CE, that measures nanoparticle surface area concentration. The surface area concentrations of unimodal and multimodal polydispersed aerosols measured by the DC2000CE were less than the surface area concentrations measured by the reference instruments. The differences in results were attributed to a difference of measuring active versus geometric surface area concentration and the design of the DC2000CE. The maximum measurable active surface area concentration (2,500 mm2 m-3) was found to be greater than the manufacturer stated maximum (1000 mm2 m-3). Moving or vibrating a DC2000CE while taking measurements can cause the appearance of increased surface area concentration results. The DC2000CE has limitations that must be acknowledged when using the DC2000CE to measure airborne nanoparticle surface area concentrations in a workplace. A four stage pDB (3.2 kg) composed of a screen-type diffusion battery, solenoid valve system, and an electronic controller was developed. The pDB was combined with a CPC and a data inversion was created that could be used to solve for the number median diameter, geometric standard deviation, and particle number concentration of a unimodal distribution. The pDB+CPC with inversion was evaluated using unimodal propylene torch exhaust and incense exhaust. For particle number concentration of particles with diameters less than 100 nm, the pDB+CPC with inversion results were between 86% to 109% of reference instrument results when the inversion did not solve to an inversion constraint and between 6% to 198% for results that solved to an inversion constraint. When coupled with a direct-reading instrument, the pDB with an inversion was able to measure the size distribution of particles with a NMD smaller than 290 nm.

Noble metal nanomaterials have numerous uses in plasmonic and surface enhanced Raman scattering (SERS) detection applications; however, upon the addition of analytes, nanomaterials often undergo uncontrolled aggregation which leads to inconsistent signal intensities. To overcome this limitation, the effect of gold nanosphere concentration, column purification, and surface chemistry functionalization using internally etched silica stabilization methods was investigated on SERS assays for small molecule detection. Nanostructure composition, size, shape, stability, surface chemistry, optical properties, and SERS-activity were monitored using localized surface plasmon resonance (LSPR or extinction) spectroscopy, transmission electron microscopy (TEM), and Raman spectroscopy. First, the behavior of citrate-stabilized gold nanospheres was monitored as a function of molecular surface coverage. Both extinction and SERS spectral intensities increased linearly below monolayer functionalization. Above this value, however, uncontrolled nanoparticle aggregation occurred and large but irreproducible SERS signal intensities were monitored. Next, gold nanoparticles were encapsulated with varying silica shell thicknesses and purified using traditional centrifugation steps and/or column chromatography. Relative to the traditionally purified (i.e. centrifuged) samples, the SERS responses from small molecules using the column purified nanoparticle samples followed a well-known SERS distance-dependence model. Thus, surface chemistry cannot form more than a 2 nm thick layer on gold nanospheres if SERS applications were targeted. To overcome these challenges, gold nanospheres encapsulated with a thick silica shell were made SERS-active by etching the internal silica layer near the metal surface. During the synthesis of these internally etched silica-coated gold nanospheres, the LSPR wavelength shift, a parameter related to the effective local refractive index near the gold core, was monitored instead of etching time, in order to produce nanostructures with more uniform internal silica etching from sample to sample. The SERS-activity of a target molecule using these nanostructures was measured as a function of LSPR wavelength shift. SERS signal intensity increased, which suggested that more analyte molecules were able to bind to the gold surface because of the larger pore size in the silica layer near the metal core. Further exploration of these findings should increase the integration of solution-phase nanoparticles in more predictable functions in future applications, resulting in more quantitative and reproducible molecular detection in complex sample matrices, including biological and environmental samples.

Cancer is the second leading cause of death in the USA, following cardiovascular disease. Treating cancer using conventional therapies is associated with low response rates and high toxicity, because these therapies usually lack specific tumor accumulation. Loading anticancer drugs into intelligently designed polymeric nanoparticles (NPs) can serve in delivering these drugs specifically to the tumor site, thus boosting their efficacy and reducing any associated off target toxicity. Targeting NPs to the tumor site can occur through either passive or active means. In passive targeting, NPs of specific size and surface characteristics can exploit the tumor’s erratic vasculature and occluded lymphatic drainage to extravasate the systemic circulation and accumulate preferentially at the tumor site. Active targeting mandates grafting the surface of NPs with a ligand that specifically interacts with a protein expressed at higher levels at the tumor site, in comparison to elsewhere in the body. In the current research, we independently investigated the utilization of passive and active targeting strategies to treat aggressive forms of cancer. Initially, passively targeted poly(lactic-co-glycolic acid) (PLGA) NPs to treat aggressive forms of endometrial cancer (EC) were investigated. A novel combination of soluble paclitaxel (PTX), a first line chemotherapy for EC, and soluble BIBF1120 (BIBF, nintedanib), an antiangiogenic molecular inhibitor, was first tested against three EC cell lines bearing different p53 mutations. The results showed that only EC cells with loss of function (LOF) p53 were sensitive to the combination therapy, indicating the potential of this combination to engender synthetic lethality to PTX. Next, NPs loaded with PTX were investigated with respect to the impact of varying the polymer lactic acid to glycolic acid ratio and the surfactant type on the major physicochemical properties of the prepared nanoparticles, drug loading, cellular uptake, cytotoxicity, and drug release. The optimum formulation was then loaded with BIBF and the combination of independently loaded passively targeted NPs were further evaluated for in vivo activity against a xenograft model of LOF p53 EC. The combination of independently loaded NPs exhibited the highest reduction in tumor volume and prolonged survival when compared to soluble PTX, PTX NPs or untreated control. These data highlight this specific combination of NPs as a novel promising therapy for LOF p53 EC. In a second study, the use of actively targeted NPs to treat liver cancer was explored. In this study, a combination of small interfering RNA (siRNA) against astrocyte elevated gene-1 (AEG-1), and all-trans retinoic acid (ATRA) was investigated as a new therapy for hepatocellular carcinoma (HCC). AEG-1 is a highly expressed oncogene that is directly involved in HCC progression and aggressiveness, in addition to reducing the ability of retinoic acid to induce apoptosis in HCC cells. First, a new conjugate was synthesized that was capable of delivering siRNA selectively to HCC cells, using galactose as a targeting moiety. The conjugate was prepared by linking poly(amidoamine) (PAMAM) dendrimers, polyethylene glycol (PEG) and lactobionic acid (Gal, disaccharide containing galactose) (PAMAM-PEG-Gal). We confirmed the synthesis of the conjugate using 1H-NMR, Mass spectrometry and Matrix-Assisted Laser Desorption/Ionization (MALDI) Mass Spectrometry. Next, nanoplexes of the synthesized conjugate, PAMAM-PEG-Gal, and AEG-1 siRNA were prepared. Nanoplexes were further characterized for their size, surface charge, morphology, and electrophoretic mobility to identify the optimum complexation ratio between PAMAM-PEG-Gal and the siRNA. Then, mice bearing orthotopic luciferase expressing HCC cells were treated with the optimum nanoplex formulation. Results showed that a combination of AEG-1 nanoplexes and ATRA results in a significant reduction in luciferase expression, reduced liver weight, lower AEG-1 mRNA levels and increased apoptosis, when compared to utilizing nanoplexes with silencing control (siCon), siCon+ATRA, or AEG-1 nanoplexes alone. The results indicate that the combination of liver-targeted AEG-1 nanoplexes and ATRA may be a potential treatment for aggressive HCC. These data place targeted NPs as a promising efficient delivery system for cancer treatment.

Composite magneto-dielectric materials have been investigated over the years because of their potential applications in RF and microwave devices as the dielectric constant and permeability can be individually changed in these materials. In the recent past, there is a renewed interest in systems classified as ferroelectromagnets or multiferroics, which possess simultaneous ferroelectric and magnetic ordering as well as interesting magnetoelastic phenomena. In all these ferrite-ferroelectric materials, the coupling between the permeability (μ) of the magnetically ordered phase and permittivity (e) of the ferroelectric phase make them attractive candidates for multifunctional applications. Ba0.5Sr0.5TiO3 (BSTO) is a ferroelectric with potential applications in tunable filters, antennas, and thin film capacitors. BaFe12O19 (BaF) is a hard ferromagnet with large in-plane anisotropy which makes it promising for use in microwave and RF devices that need permanent magnets for biasing requirements. We have used magnetron sputtering to deposit multilayer films of BSTO and BaF on Al2O3 and heated Si/SiO2. To our knowledge this is the first attempt at combining these technologically important materials in multilayer form. The as-deposited films were amorphous and post-annealing was optimized until distinct BSTO and BaF x-ray peaks could be identified. Surface and images were obtained by atomic force microscopy (AFM) and scanning electron microscopy (SEM). The multilayer structure and BSTO/BaF interfaces were identified using cross-sectional SEM. Magnetic properties of the multilayer films were measured using a Physical Properties Measurement System (PPMS) by Quantum Design at 10K and 300K over a range of magnetic field (0 < H < 7T). We have attempted to correlate some of the magnetic characteristics with the film microstructure. In addition, we have deposited layers of Fe3O4 nanoparticles onto both bare Si/SiO2 substrates and the surfaces of the multilayers using Langmuir-Blodgett technique. Preliminary images of monolayer Fe3O4 particles reveal some ordering present. We have also used the PPMS to look at the magnetic properties of the particles, both by themselves and deposited onto the multilayers to see what magnetic effects the particles have on ferrite-ferroelectric systems.

Present state-of-the-art hydrogen sensors are limited by a number of defects such as poisoning effects, slow response, and/or the range of concentrations that can be detected. Thus, hydrogen sensors are currently under investigation. In the search for the ultimate sensor, a variety of materials have been employed as the sensing layer. One of these materials is palladium. Palladium is widely used for hydrogen sensing due to its high selectivity and property of spontaneously absorbing hydrogen. Thin and thick film palladium hydrogen sensors have been reported, as well as palladium nanostructures. Specifically, palladium nanowires for hydrogen sensing have had improved results relative to other types of sensors; these have been reported with a response time down to 75ms and do not suffer from poisoning effects. Additionally, the fabrication of these nanostructures via electrodeposition is simple and cost efficient. For this reason, palladium nanostructures were chosen as the front-end for a novel hydrogen sensor. The nanostructures were to be employed as the sensing front-end of a Surface Acoustic Wave (SAW) sensor. It was theorized that the response time would be vastly improved if these were used as opposed to a thin or thick palladium film due to the decreased hydrogen diffusion distance, which is a result of the structures being one-dimensional. Because it was theorized that the dimensions of the nanostructures play an integral role in the response time to hydrogen, control of the morphology was required. This control was achieved by varying the plating variables in the electrodeposition experiments. The plating variables investigated were deposition potential, time, and counter-electrode area. The dimensions of the resulting nanostructures were measured via Scanning Electron Microscopy (SEM) and correlated to the conditions of the electrodeposition experiments. Nanowires under 40nm were successfully fabricated.

Magnetic nanoparticles embedded in polymer matrices have excellent potential for electromagnetic device applications like electromagnetic interference (EMI) suppression. Using chemical precipitation methods and Nanogen , a microwave plasma method, we have synthesized various nanoparticles including iron, polystyrene-coated iron, iron oxide (both hematite and magnetite), nickel ferrite, and manganese zinc ferrite. We have synthesized polymer nanocomposites of polymethylmethacrylate (PMMA), polystyrene (PS), and polypyrrole (PPy) doped with varying concentrations of these nanoparticles. These nanocomposites were processed using melt blending and sonication techniques. The concentration of nanoparticles was varied in a controlled way. Although polymer processing conditions were optimized to achieve good uniform dispersion of the nanoparticles in the polymer matrix, surface characterization with SEM indicates areas of clustering of the nanoparticles. This agglomeration is attributed to the particle interactions mediated by steric forces in the polymer matrix. Static magnetic properties such as susceptibility and M-H loops were studied using a Physical Property Measurement System (PPMS). The variation of the magnetic responses were consistent with the varying volume concentration of the nanoparticles, the polymers themselves contributing diamagnetic responses. Overall, the reasonable dispersion and control over magnetic properties achieved in our experiments is promising for electromagnetic applications of these materials.

Respiratory Syncytial Virus (RSV) is a potentially life-threatening respiratory pathogen that infects approximately 64 million children and immunocompromised adults globally per year. Currently, there is a need for prophylactic and therapeutic approaches effective against primary and secondary RSV infections. This project focuses on the development of a simple, smart, and scalable anti-RSV nanotherapeutic that combines novel cellular antiviral defense mechanisms targeting the inhibition of viral fusion and replication. An ICAM-1 targeted liposomal nanocarrier will be synthesized and coated with a layer of chitosan containing the anti-fusion HR2-D peptide as an extracellular defense mechanism. Additionally, chitosan complexed to dual expressing short hairpin RNA (shRNA) recombinant plasmids will be encapsulated within the nanocarrier, and provide an intracellular defense mechanism that will interfere with the expression of the NS1 and P proteins. In combination, both defense mechanisms are expected to induce a synergistic anti-RSV effect that will surpass those of conventional therapeutics. Through this research, the NS1 and P containing plasmid (pSH-NS1-P) was cloned, and the nanotherapeutic was successfully synthesized. Based on the acquired results, pSH-NS1-P was shown to express anti-RSV effects, and it was also concluded that both inserts were producing active shRNA. Additionally, the anti-RSV efficiency of HR2-D was confirmed. Overall, this research will lead to development of a dual-mechanistic anti-viral nanotherapeutic.