Targeted delivery of drugs directly to the lung epithelium is a promising, though challenging, strategy for the treatment of diseases that affect the lung tissues, such as infections caused by cell-penetrating pathogens, cystic fibrosis, and cancer. With appropriate surface functionality, such as through the attachment of ligands that recognize receptors on cellular surfaces, particulate carriers show improved efficiency in penetrating cells in vitro. A useful class of ligands is produced by many natural human pathogens that infect the respiratory tract. A variety of phylogenetically distinct respiratory bacterial pathogens, such as Haemophilus influenzae, invade host cells in the upper airways by binding of the platelet-activating factor (PAF) receptor via lipooligosaccharide (LOS) glycoforms. By expressing host carbohydrate structures, including phosphorylcholine (ChoP), as a terminal structure on the LOS, the bacteria exhibit molecular mimicry of the host and are able to evade the host immune system. The effectiveness of LOS to induce cellular uptake of the bacteria is dependent on the specific glycoform, with higher ChoP content inducing more bacterial adherance into the lung epithelial. These ligands naturally expressed on bacterial cell surfaces can be isolated and utilized as targeting ligands for delivery vehicles. The studies described in this thesis focus on the development of particulate drug carriers coated with LOS bacterial ligands to enhance the targeting and binding of the carriers to the lung epithelium. Three NTHi clinical isolates were screened to select the strain with the highest ChoP level, and NTHi 3198, an isolate from a patient with chronic obstructive pulmonary disease (COPD), was selected due to its high ChoP activity. LOS from NTHi 3198 was isolated from the bacterial cell membrane, and its activity verified using dot immunoblot and ELISA techniques. Particles (0.2 and 1 µm) composed of polystyrene or poly(lactic-co-glycolic acid) were passively coated with 0.005-50 µg/mL of the isolated LOS 3198 with or without gelatin, coated with gelatin alone, or left uncoated. The LOS coating on the particles was verified using either XPS or ELISA. The association of particles with human bronchial epithelial cells was investigated using two cell culture models, 16HBE14o- and Calu-3, as a function of particle concentration and incubation time. The expression of PAFR on both cells types was confirmed, though the expression of PAFR on 16HBE14o- cells was significantly greater than on Calu-3 cells. Enhancement of 0.2 µm particle-cell association was achieved through coating of the particles with LOS. However, no significant difference in particle-cell association was observed for the 1 µm particles based on particle coating. Control particles of 0.2 µm size, those coated with gelatin (with or without LOS) or uncoated, exhibited low cell binding with a maximum of about 10-18% of cells associated with particles. The ability of the LOS ligand to enhance particle-cell association was coating concentration dependent, with a low coating concentration of LOS having little effect on association, but a concentration 1000-fold higher causing a doubling of the percentage of cells associated with particles at 24 hours. This enhancement was attributed to increased cellular binding of the 0.2 µm particles to the cell surface by confocal microscopy, and was further increased by activating the PAFR prior to incubation with particles. These results suggest the potential application of LOS as a targeting ligand for lung epithelial cells, especially under conditions where PAFR has been activated, such as occurs in lungs infected with Haemophilus influenzae. A significant reduction in particle-cell association was observed when particles were incubated with Calu-3 cells due to the presence of mucus on the cellular surface. This suggests that further optimization of the drug carrier system is needed to efficiently overcome the mucosal fluids.

Nanoparticles have gained growing attention of the scientific community over the past few decades due to their high potential to be used in diverse industrial applications. Nanoparticles often possess superior characteristics, such as catalytic activity, photochemical activity, and mechanical strength, compared to their bulk counterparts, making them more desirable in different industrial applications. During the past few decades, the use of the nanoparticles in various industries has been increased. With increasing usage release of nanoparticles into the environment has also increased. There is a growing concern about the nanoparticle toxicity and numerous studies have shown the toxic effects of different nanoparticles on various plants, animals, and microorganisms in the environment. Toxicity of nanoparticles is often attributed to their morphology and their ability to undergo different transformations in the environment. These transformations include aggregation, dissolution, and surface adsorption. Natural organic matter (NOM) are the most abundant natural ligands in the environment which include Humic acid and Fulvic acid. These high molecular weight organic molecules have complex structures and contain many different functional groups such as carboxylic acid groups, hydroxyl, amino and phenolic groups that can interact with the nanoparticle surface. The nature and the intensity of the interaction are dependent on several factors including the size and the surface functionality of nanoparticles and pH of the medium. The smaller the nanoparticle, the higher the adsorption of NOM due to the high surface to volume ratio of smaller particles. Functional groups on the surface dictate the surface charge of the nanoparticles in water depending on the acidity. The higher the acidity, higher the adsorption of NOM due to increased electrostatic attractions between positively charged nanoparticles and the negatively charged NOM molecules. Adsorbed NOM on nanoparticles affect the other transformations such as aggregation and dissolution and can in turn alter the reactivity and toxicity of the nanoparticles. Therefore, effect of NOM is an important factor that should be considered in environmental toxicity related studies of nanoparticles.

Gene therapy has the potential to treat a wide variety of diseases. Delivering nucleic acids, such as DNA and mRNA, allows for the production of an aberrant or absent protein that is causing the disease. Delivery of genes via viruses is very efficient but falls short because of other issues. Nonviral delivery, on the other hand, struggles with efficiency but has advantages in terms of lack of immunogenicity, ease in production, and carrying capacity. DNA is much more stable than mRNA, and the protein production from DNA persists for a longer time. However, DNA delivered to cells must pass through the nuclear envelope to produce protein. Nuclear penetration with nonviral DNA delivery in vivo has not yet been accomplished. mRNA only needs to be delivered to the cytoplasm. Recent interest in nonviral delivery of mRNA has surged upward because delivery of mRNA to various cells in vivo has proven successful. Yet mRNA still struggles with nuclease stability, which is a major impediment toward efficient expression. A polyacridine PEG-peptide (PEG-peptide) has been previously used to stabilize DNA against nuclease hydrolysis by binding through ionic and intercalative interactions. Binding of PEG-peptide to DNA results in a PEGylated nanoparticle, or polyplex, and which protects the DNA. The same PEG-peptide was applied to mRNA. To increase the ability of PEG-peptide to bind through intercalation, a reverse complementary strand was hybridized to the mRNA, forming double stranded mRNA (dsmRNA). In a similar manner to DNA, complexing dsmRNA or single stranded mRNA (ssmRNA) with PEG-peptide resulted in formation of PEG-peptide polyplexes. A dsmRNA polyplex was much more resistant to ribonuclease challenge in vitro than a ssmRNA polyplex. The mRNA constructs were tested in vivo by hydrodynamic dosing. dsmRNA was found to be translationally competent by producing a high level of luciferase reporter enzyme in the liver of mice. When the reverse strand length was modified such that it hybridized with only the coding region, leaving the untranslated regions (UTRs) and poly(A) tail single stranded, the in vivo translatability (level of expression) and persistence (duration of expression) of dsmRNA was equivalent to that of ssmRNA. Full hybridization of the reverse strand with the coding region, the UTRs, and poly(A) tail resulted in a decrease of in vivo translatability. However, the circulatory stability (an in vivo measure of resistance to degradation in blood) was greatly increased when the reverse strand was fully hybridized. The persistence of expression of exogenously delivered mRNA is poor in comparison to DNA. The first step in mRNA decay in the cytoplasm is predominantly poly(A) tail shortening, or deadenylation. To address the persistence issue, mRNA with nonadenosine extensions at the 3’ end of the poly(A) tail was synthesized to inhibit deadenylation-dependent mRNA decay. However, increase of the length of tail extension resulted in a concomitant overall decrease in translatability and no increase in persistence. Hybridization of a DNA oligo to the origin of the tail extension activated endogenous RNase H, cleaving the tail extension, exposing the poly(A) tail, and reactivating the mRNA for high level translation, although no increase in persistence was seen with this strategy. A structured tail extension consisting of two human β-globin 3’UTR sequences increased persistence but also decreased overall translatability. Enzymatic poly(A) tailing of this structured tail extension brought back the translatability but simultaneously lost the persistence gain. While this study on poly(A) tail extension mRNA did not produce a highly active mRNA that had increased persistence, its results may be applicable toward other gene therapy applications. Other efforts to increase the metabolic stability or persistence of mRNA were pursued. Scavenger receptors on resident liver macrophages remove polyplexes from the blood by phagocytosis. Saturation of the scavenger receptors by coadministration of a scavenger receptor inhibitor resulted in increased circulatory stability of dsmRNA. However the scavenger receptor inhibitor was toxic in mice. Another effort to increase the persistence of gene expression in vivo was utilizing an autogene. Autogenes are able to drive the expression of a DNA-based gene outside of the nucleus. In its final form, the autogene did not produce expression. It is an exciting time to be in the field of mRNA gene therapy. Hopefully the research presented in this thesis will factor in to the knowledge base that can treat and cure human diseases.

The rapid increase in thermoelectric (TE) materials R&D is a consequence of the growing need to increase energy efficiency and independence through waste heat recovery. TE materials enable the direct solid-state conversion of heat into electricity, with little maintenance, noise, or cost. In addition, these compact devices can be incorporated into existing technologies to increase the overall operating efficiency. High efficiency TE materials would enable the practical solid-state conversion of thermal to electrical energy. Optimizing the interdependent physical parameters to achieve acceptable efficiencies requires materials exhibiting a unique combination of properties. This research reports two methods of thermoelectric enhancement: lattice strain effects in silicon-germanium alloy type I clathrates and the nanostructured enhancement of lead chalcogenides. The synthesis and chemical, structural, and transport properties characterization of Ba8Ga16SixGe30-x type I clathrates with similar Ga-to-group IV element ratios but with increasing Si substitution (4 < x < 14) is reported. Substitution of Si within the Ga-Ge lattice framework of the type I clathrate Ba8Ga16Ge30 results in thermoelectric performance enhancement. The unique dependences of carrier concentration, electrical resistivity, Seebeck coefficient, and carrier effective mass on Si substitution level, may imply a modified band structure with Si substitution. These materials were then further optimized by adjusting the Ga-to-group IV element ratios. Recent progress in a number of higher efficiency TE materials can be attributed to nanoscale enhancement. Many of these materials demonstrate increased Seebeck coefficient and decreased thermal conductivity due to the phenomenological properties of nanometer length scales. To satisfy the demands of bulk industrial applications requires additional synthesis techniques to incorporate nanostructure directly within a bulk matrix. This research investigates, for the first time, dense dimensional nanocomposites prepared by densifying nanocrystals synthesized employing a solution-phase reaction. Furthermore, the carrier concentration of the PbTe nanocomposites can be adjusted by directly doping the nanocrystals, necessary for power factor optimization. These materials were fully characterized using a low temperature TE transport measurement system, and exhibit enhanced power factors when compared to bulk polycrystalline PbTe with similar carrier concentrations.

Colloidal, metallic nanoparticles have myriad applications, but they are most ideal when they are monodisperse, and demonstrate maximum catalytic utility when they are small (< 5 nm) and uncoated; because their surface area is accessible and maximized. Laser- assisted metal nanoparticle synthesis is a ‘green’ method that has become a topic of active research because it is able to produce uncoated or ‘naked’ products. The nanoparticles synthesized in this work were formed through the reduction of metal salts in aqueous solutions; but the reducing agent is an electron-dense microplasma generated by the laser pulse interacting with the media. Because no chemical reducing agents or stabilizers are needed, the products have no surfactants. The underlying reaction mechanisms that drive this type of synthesis are generally understood, however, there is insufficient detail that would allow control over the formation of ultimate product morphologies and size distributions. The metals examined in this thesis are: gold, whose formation follows an autocatalytic rate law; and silver, whose formation follows a first-order rate law. Through my research, I was able to explore the effects that physical parameters (such as laser pulse settings) and chemical parameters (such as radical scavenger addition) have on laser-assisted gold or silver nanoparticle synthesis. My research, outlined in this thesis, is therefore focused on elucidating such details and distilling them into methods of control in order to better predict and tune nanoparticle products.

The emergence of nanotechnology has increased the concern of exposure to nanoparticles through inhalation. Studies have examined the performance of filtering facepiece respirators against engineered nanoparticles. This has been done by the generation and dispersal of certain particles in a given size distribution, which have then been run through experimental set-ups involving Condensation Particle Counters, Scanning Mobility Particle Sizers, and high efficiency performance filters for a set flow. Published studies have shown that the respirators used do provide expected levels of filtration protection against nanometer-sized particles. However, studies have not examined or applied different types of nanoparticle samples - different particle types have differing morphologies and physical characteristics that could affect filter performance. This study has exposed NIOSH-approved N95 facepiece respirators to six different types of engineered nanoparticles: aluminum oxide, iron oxide, single-walled carbon nanotubes, synthesized diamond, silicon dioxide, and titanium dioxide. In addition, N95 respirators have not been commonly exposed to differing concentrations of an aerosol in order to observe a shift in the primary penetrating particle size and a shift in the overall size distribution. This study challenged N95 respirators to four different concentrations of sodium chloride: 0.1, 1, 10, and 50 mg/ml. Another concern is whether or not a prolonged exposure of a single respirator affects the overall performance and protection from an aerosol, especially engineered nanoparticles, since very few studies have been done regarding this matter. N95 respirators were exposed to several types of engineered nanoparticles in a respirator testing apparatus at a set flow rate, examined for penetration with an SMPS, CPC, and DMA given these conditions: differing concentrations of sodium chloride, different engineered particles, and an extended duration of exposure to both sodium chloride and 15-nm titanium dioxide. This study showed that the primary penetrating particle size through an N95 facepiece respirator does increase and shift with increasing concentrations of an aerosol; however, the overall size distribution did not seem to shift much. Penetration decreased as sodium chloride concentration increased. Different nanoparticles had differing primary penetrating particle sizes through the respirator; however, penetration of these particles was similar to one another with the exception of iron oxide which had quite a high penetration percentage. A decrease in N95 respirator performance was observed when exposed to a 1 mg/ml solution of sodium chloride, as penetration increased with prolonged exposure. However, this did not seem to be the case when the respirator was exposed to a 6.67 mg/ml suspension of 15-nm titanium dioxide, as the penetration over the extended period of time was similar to one another.

Particulate matter in the atmosphere emitted from various natural and anthropogenic sources is important due to their effects on the chemical balance of the atmosphere, the Earth's climate, human health and biogeochemical cycles. Although there have been many studies performed to understand the above effects, there still remains substantial uncertainty associated with processes involved and thus it is difficult for current atmospheric chemistry and climate models to reconcile model results with field measurements. Therefore, it is important to have better agreement between models and observations as the accuracy of future atmospheric chemistry and climate predictions depends on it. In this research, a greater understanding of the role of mineral dust chemistry was pursued through focused laboratory studies in order to better understand fundamental processes involved. In particular, studies to further understand the photochemistry of adsorbed nitrate, an important inorganic ion associated with particulate matter exposed to gas-phase nitrogen oxides, were conducted using Al2O3, TiO2 and NaY zeolite to represent non-photoactive components, photoactive components and aluminosilicate respectively, present in mineral dust. These studies reveal that photochemistry of nitrate adsorbed on mineral dust is governed by wavelength of light, physicochemical properties of dust particles and adsorption mode of nitrate. Gas phase NO2, NO and N2O are the photolysis products of nitrate on oxide particles under dry conditions. In contrast, nitrate adsorbed on zeolite is converted mainly to adsorbed nitrite upon irradiation. This nitrite yield is decreased with increasing relative humidity. Gas phase N2O is the main photolysis product of nitrate adsorbed in zeolite in the presence of co-adsorbed ammonia. Water adsorbed on semiconducting TiO2 can be photochemically converted to hydroxyl radicals. These hydroxyl radicals can be involved in surface mediated as well as gas phase oxidation reactions in the presence of cyclohexane. Another focus of this dissertation was to investigate the oxidation of sulfur dioxide oxidation in the presence of mineral aerosol, particularly, coal fly ash (FA), γ-Fe2O3 and Arizona test dust (AZTD), a model for mineral dust aerosol. Depending on the temporal evolution of Fe(II), we proposed that S(IV) oxidation in the presence of FA and γ-Fe2O3 initially occurs through a heterogeneous pathway and a homogeneous pathway is also possible over later time scales. S(IV) oxidation in the presence of AZTD appears to be mostly heterogeneous and does not lead to iron dissolution. Overall, these studies suggest that the rate, extent and products of atmospheric S(IV) oxidation can be highly variable and heavily dependent upon the nature of aerosol sources, thereby precluding simple generalizations about this reaction when modeling atmospheric processes involving diverse mineral dust aerosols. With the recent development in nanotechnology, nanoparticles are becoming a major fraction of atmospheric particulate matter. These particles can undergo aging under ambient conditions at any stage of their life cycle. This impacts the fundamental properties of these materials and therefore the behavior in the environment and interactions with biomolecules and biological systems. ZnO and CuO nanoparticles form adsorbed carbonate phases upon exposure to CO2 and water vapor. These carbonates become more solvated as the relative humidity is increased. Presence of carbonate phases on ZnO particles increases their water solubility. Thus, overall the work reported in this dissertation provides insights into heterogeneous and multiphase atmospheric chemical reactions in the presence of mineral aerosol and atmospheric aging of nanoparticles.

Cette thèse concerne l’élaboration par réaction “click” CuAAC denouveaux nanomatériaux présentant diverses applications, en particulier en catalyse.Ces macromolécules (dendrimères, dendrimères supportés sur oxide et polymères)comprenant des cycles 1,2,3-triazoles ont été utilisés pour stabiliser desnanoparticules essentiellement de palladium actives en catalyse de couplage C-C,réduction du 4-nitrophenol et oxydation des alcools dans des solvants aqueux.L’utilisation de ces nanoparticules à l’échelle du ppm traduit leur efficacité et l’aspectécologique visé avec ce projet. L’intégration d’unités triazolylbiferrocéniques au seinde ces polymères a permis d’étendre la gamme d’applications de ces matériaux auxsondes électrochimiques, réduction d’ions métalliques en nanoparticules, composéspoly-électrolytes, poly-électrochromes, à valence mixte. L’imprégnation denanoparticules de palladium stabilisées par des dendrimères sur support magnétiquea permis d’augmenter la robustesse des catalyseurs ainsi que leur recyclablité paraimantation. / This thesis concerns the synthesis by “click” CuAAC reactions of newnanomaterials that have various applications, in particular in catalysis. Thesemacromolecules are dendrimers, supported dendrimers and polymers that contain1,2,3-triazole rings and were used in the stabilization of essentially palladiumnanoparticles (PdNPs). These PdNPs are extremely active in the catalysis in greensolvents of C-C coupling, reduction of 4-nitrophenol and selective oxidation ofalcohols. The use of these nanoparticle catalysts at the ppm level shows theirefficiency and their ecological aspect. The integration of biferrocene units in thepolymers allowed expanding their applications to electrochemical sensors, reductantsof metallic ions to nanoparticles, polyelectrolytes, polyelectrochromic, and mixedvalentcomplexes. The impregnation of PdNPs stabilized by dendrimers on magneticsupport led to the increase of the catalyst robustness and recyclability using amagnet.

The purpose of this study was to investigate whether or not differing base metals and filler wires used during welding processes contributed to differing amounts of ultrafine particles (UFP) and nanoparticles being emitted during the welding procedure. The study was also conducted to determine UFP and nanoparticle exposure in the breathing zones of the welders as well as the breathing zones of pipefitters and fire watchers, who commonly sit 6ft behind the welding arc. In order to determine if UFP and NP exposures differed with base metal and filler wire, all welding processes utilized the same welding machine for metal inert gas (MIG), the same wire speed, and the same voltages during each welding process. The only variation in welding procedures were cover gases used, base metals, and filler wires. Measurements gathered during welding procedures were conducted in the breathing zone of the welder and pipefitters consisted of UFP measurements taken by two different condensation particle counters (CPC), which operated in synchrony at the start and cessation of the welding process. NP measurements were taken by a NanoScan Scanning Mobility Particle Sizer (SMPS) and were also placed in the breathing zone of the welder. Lastly, particle characterization measurements for transmission electron microscopy (TEM) and energy dispersive spectroscopy (EDS) were gathered using a filter attached to a high flow pump, which was placed in the breathing zone of the welder. According to the results, base metal and filler wire do emit differing amounts of NP and UFP during the welding processes. Carbon steel emits the highest amount of nanoparticles, while stainless steel emits the second highest amount, and inconel emits the least. The results also concluded that welders are exposed to a greater concentration of nanoparticles and UFPs than those experienced by pipefitters who stand 6ft from the welding arc.

The purpose of this research is to demonstrate the ability to generate and characterize a nanometer sized aerosol using solutions, suspensions, and a bulk nanopowder, and to research the viability of using an acoustic dry aerosol generator/elutriator (ADAGE) to aerosolize a bulk nanopowder into a nanometer sized aerosol. The research compares the results from a portable scanning mobility particle sizer (SMPS) to the more traditional method of counting and sizing particles on a filter sample using scanning electron microscopy (SEM). Sodium chloride aerosol was used for the comparisons. The sputter coating thickness, a conductive coating necessary for SEM, was measured on different sizes of polystyrene latex spheres (PSLS). Aluminum oxide powder was aerosolized using an ADAGE and several different support membranes and sound frequency combinations were explored. A portable SMPS was used to determine the size distributions of the generated aerosols. Polycarbonate membrane (PCM) filter samples were collected for subsequent SEM analysis. The particle size distributions were determined from photographs of the membrane filters. SMPS data and membrane samples were collected simultaneously. The sputter coating thicknesses on four different sizes of PSLS, range 57 nanometers (nm) to 220 nm, were measured using transmission electron microscopy and the results from the SEM and SMPS were compared after accounting for the sputter coating thickness. Aluminum oxide nanopowder (20 nm) was aerosolized using a modified ADAGE technique. Four different support membranes and four different sound frequencies were tested with the ADAGE. The aerosol was collected onto PCM filters and the samples were examined using SEM. The results indicate that the SMPS and SEM distributions were log-normally distributed with a median diameter of approximately 42 nm and 55 nm, respectively, and geometric standard deviations (GSD) of approximately 1.6 and 1.7, respectively. The two methods yielded similar distributional trends with a difference in median diameters of approximately 11 - 15 nm. The sputter coating thickness on the different sizes of PSLSs ranged from 15.4 - 17.4 nm. The aerosols generated, using the modified ADAGE, were low in concentration. The particles remained as agglomerates and varied widely in size. An aluminum foil support membrane coupled with a high sound frequency generated the smallest agglomerates. A well characterized sodium chloride aerosol was generated and was reproducible. The distributions determined using SEM were slightly larger than those obtained from SMPS, however, the distributions had relatively the same shape as reflected in their GSDs. This suggests that a portable SMPS is a suitable method for characterizing a nanoaerosol. The sizing techniques could be compared after correcting for the effects of the sputter coating necessary for SEM examination. It was determined that the sputter coating thickness on nano-sized particles and particles up to approximately 220 nm can be expected to be the same and that the sputter coating can add considerably to the size of a nanoparticle. This has important implications for worker health where nanoaerosol exposure is a concern. The sputter coating must be considered when SEM is used to describe a nanoaerosol exposure. The performance of the modified ADAGE was less than expected. The low aerosol output from the ADAGE prevented a more detailed analysis and was limited to only a qualitative comparison. Some combinations of support membranes and sound frequencies performed better than others, particularly conductive support membranes and high sound frequencies. In conclusion, a portable SMPS yielded results similar to those obtained by SEM. The sputter coating was the same thickness on the PSLSs studied. The sputter coating thickness must be considered when characterizing nanoparticles using SEM. Finally, a conductive support membrane and higher frequencies appeared to generate the smallest agglomerates using the ADAGE technique.