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Currently, about one third of the world's population is latently infected with Mycobacterium tuberculosis and about 4 million people die from the disease annually worldwide. Although treatment with antimicrobials can be curative, many people fail to complete the prescribed therapeutic regimen which can increase the risk of disease re-emergence, spread of infection to others and development of drug resistance. An improved approach is urgently needed for patient compliance. Development of safe and effective colloidal drug delivery systems may reduce the amount and frequency of antimicrobial therapy needed. The major goal of this research effort is to explore the safety and efficacy of antimicrobial loaded nanoparticles against M. avium. Various in vitro efficacy studies were done with a) amikacin-loaded nanoparticles, b) clarithromycin-loaded nanoparticles, and c) with aerogel nanoparticles loaded with rifampicin, clarithromycin and ethambutol. Clarithromycin (CLA) and amikacin (AMK) loaded nanoparticles showed a significant reduction in viable M. avium compared to free antibiotics and untreated controls. Cytotoxicity assays revealed that all types of drug-laden nanoparticles were non-toxic to J774A.1 mouse macrophage cells at therapeutic doses. In vivo efficacy studies showed that only amikacin-loaded polymeric nanoparticles improved clearance compared to free amikacin in M. avium infected BALB/c mice. In general, none of the nanoparticle formulations elicited any significant microscopic lesions in the organs of infected mice at tested doses. Each nanoparticle formulation was analyzed physicochemically for size, zeta potential, amount of drug load, minimum inhibitory concentration (MIC) and stability. Both the AMK and CLA polymeric nanoparticles were below 200 nm in size and had a slightly negative overall surface charge, aerogel nanoparticles were somewhat larger in size. The amount of drug load varied between all three nanoparticles and is largely dependent on the chemical structure and interactions between the nanoparticle and drug. The AMK and CLA nanoparticles were relatively stable under varying environmental conditions and time points and had MIC ranges equivalent to the respective free drugs. / Ph. D.

The exploration in the use of nanomaterials for a multitude of different applications has grown within the last few years. This is largely due to the vast number of features exhibited by nanoscale materials when compared to their bulk counterparts. The use of nanomaterials in environmental applications can come in different facets, such as, the production of clean energy in solar cells and the application of nanotechnologies in coatings for building exterior surfaces. The first section of the thesis focuses on the use of nanomaterials for water remediation, since purified groundwater is still not globally accessible. Chapter 2 focuses on the use of Pd nanoparticles supported on TiO₂ (Pd@TiO₂) to photo-generate H₂ while using bacterial cells as sacrificial electron donors (SEDs) rather than chemical reagents. Different conditions were examined to investigate the photo-destruction of gram negative bacteria, E. coli, which is a microbial pollutant often found in a number of different water sources. Samples containing photocatalyst in solution were irradiated using a solar simulator, which is a light source that is similar to the solar spectrum, for applications in a flow system. Chapter 3 is a project in collaboration with Dr. Edith Amuhaya and her research group in Nairobi, Kenya exploring the use of porphyrins, an organic compound, supported on glass wool for water treatment in a flow system. Porphyrins are photosensitizers that generate reactive oxygen species (ROS) when exposed to light and oxygen. However, their high solubility in aqueous media makes it difficult to use them for water remediation and can add an extra step in the process of water purification. Therefore, we suggest attaching the porphyrins to glass wool, which is an inexpensive and inert support that can easily be removed from a flow system. Here, we explore the use of glass wool as a support for a series of different conjugated porphyrins and metalloporphyrins. We have synthesized different porphyrins bearing carboxylic group substituents to enable ease of deposition onto the amino-functionalized glass surface (glass surface modified with (3-Aminopropyl) triethoxysilane, APTES). The characterization of the materials suggests some of the porphyrins retain the ability to absorb solar light and generate reactive oxygen species upon irradiation. Antimicrobial activity and degradation of selected pollutants were also explored. The last section of the thesis discusses a different approach regarding nanoparticles. Typically, nanoparticles are used for their reactivity when they absorb light, often producing a high number of free radicals in the process. However, this high reactivity can become an issue when these free radicals cause unintended damage to biological environments. This is the case for TiO₂ used for photo-protection sunscreens, where there has been some concern regarding the free radical damage to skin. Previously, the group has synthesized TiO₂ particles in a thin shell of lignin, a natural biopolymer. Lignin is an antioxidant that can scavenge the radicals produced by the photo-excited TiO₂ and prevent them from being released into the surrounding media. Here, we further characterize and investigate the properties of the lignin on TiO₂ nanoparticles and attempt to scale up the production of the particles.

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Nanoparticles (NPs) have become a key tool in medicine and biotechnology; as drug delivery systems, biosensors, and diagnostic devices. However, the mechanism of biocorona formation on nanoparticle surfaces and their impact on drug delivery remains speculative. Nevertheless, functionalized nanoparticles have demonstrated major success in medical applications; having been shown to effectively treat disease. The mechanistic details of protein behavior on nanoparticle surfaces remain poorly understood to date; due to difficulty in determining the orientation and structure of protein on NPs. Furthermore, surface crowding, orientation, and degree of disorder have been shown to perturb the efficacy of protein on NPs; dramatically reducing their benefits. NMR and other biophysical tools can be used to characterize the nanoparticle-protein surface interactions; leading to a better understanding of the biocorona structure. This dissertation investigates the structure, orientation, and function of proteins adsorbed on gold nanoparticles (P-AuNPs). Using hydrogen-deuterium exchange and methylation studies on P-AuNPs, we have elucidated the structure and orientation of proteins on AuNP surfaces. We have also designed fusion proteins that can effectively mitigate structural-, orientation-, and activity-perturbations of P-AuNPs. The benefits of our fusion protein approach have been verified via enzymatic assay; which monitored the enzymatic activity of these P-AuNPs. Biofilms are defined as surface-anchored, multi-cellular, three-dimensional, bacterial communities. Biofilms have a serious impact on public health; because of their role in infectious diseases and medical device-related infections. S. epidermidis is the most common biofilmorming bacteria. Therefore, understanding the mechanisms of biofilm formation could lead to novel therapeutics which prevent biofilm formation. One of the most recognized proteins in the biofilm formation mechanism is the S. epidermidis autolysin domain. Therefore, we have studied the structure and behavior of S. epidermidis autolysin repeat domain R2 (R2ab) via solution NMR and other biophysical techniques. This study has provided a deeper understanding of how R2ab interacts with foreign surfaces and blood proteins; which could lead to future methods of biofilm prevention. Over the course of this dissertation, the characterization of protein-surface interactions was achieved via solution NMR and other biophysical tools; providing insightful information to the fields of medicine and therapeutics.

This study describes the use of human serum albumin (HSA)-modified gold nanoparticles (HSA-AuNPs) for the selective extraction and enrichment of high-pI protein, lysozyme (Lyz) prior to analysis by capillary electrophoresis (CE) with UV detection. HSA-AuNPs are capable of extracting Lyz from a complicated matrix because a HSA capping layer not only stabilizes gold nanoparticles in a high-salt environment but also exhibits strong electrostatic attraction with Lyz under neutral pH condition. Efficient separation of Lyz and other high-pI proteins has been successfully achieved by the filling of cationic polyelectrolyte, poly(diallydimethylammonium chloride) (PDDAC), to the background electrolyte. After capturing Lyz with HSA-AuNPs, PDDAC-filled CE can be directly used for the analysis of the extracted Lyz without the addition of the releasing agent into the extractor. The extraction efficiency relied on the pH of the solution and the concentration of HSA-AuNPs. Under optimal extraction conditions, the limits of detection at a signal-to-noise ratio of 3 for Lyz were down to 8 nM. The combination of HSA-AuNP extraction and PDDAC-filled CE has been applied the analyses of lysozyme in chicken egg white, white wine and human tear. Also, we reveal that this NP-based extraction can be coupled to matrix-assisted desorption/ionization time-of-flight mass spectrometry.

Cancer is a major public health problem worldwide due to its poor prognosis. Detection of cancer in the earliest stages is crucial for the success of therapeutic strategies to truly cure the disease. Molecular imaging provides the potential to diagnose and image cancers at an asymptomatic stage. In molecular imaging, the nanoparticles are designed to target the cancer cells. Molecular imaging is capable of assessing the molecular processes within the tumors by detecting the accumulated or targeted nanoparticles. However, for most molecular imaging systems, the background signal is a common problem, obscuring signals from specific probes and limiting sensitive detection. A hybrid imaging technique, entitled magneto-photo-acoustic (MPA) imaging, was developed as a non-invasive imaging tool to detect nanoparticles, which are used to target pathologies, with high sensitivity and specificity. Based on dual-contrast of both optical absorption and magnetic susceptibility, MPA imaging can significantly improve the molecular contrast specificity as well as investigate the interaction of nanoparticles with cells. Studies were performed using tissue-mimicking phantoms, ex vivo tissue sample and in vivo animal models of cancer. The results indicate that, coupled with dual-contrast agent, the molecular MPA imaging will allow not only mapping the pathologies located in the body, but also sensing the molecular and physiological processes. / text

The work herein consists of two projects in which nanoparticle-metallopolymer hybrid bulk-heterojunction (BHJ) systems are modified for improved performance in photovoltaic and electronic applications. The first project describes the process for growing two distinct nanoparticle compositions within the same active layer of a conducting metallopolymer composed of two metal-complexes, which are based on the N,N’-((2,2’-dimethyl)propyl)bis(5-(2,2’-bithiophene-5-yl)salcylidenimine ligand. The second project describes the synthesis of an alternative electropolymerizable ligand N,N’-((2,2’-dimethyl)propyl)bis(5-(thieno[3,2-b]thiophen-5-yl) salicylidenimine. The purpose of exchanging of bithiophene moieties for fused-ring thieno[3,2-b]thiophene units was to produce a stabilizing effect in the resulting polymer, as evidenced by a slight delay in the rate of photo-bleaching. / text

During carbon dioxide (CO₂) sequestration, CO₂ injection suffers from viscous fingering and low sweep efficiency. In addition, the lower density of CO₂ compared to in-situ brine leads to the possibility of sequestered CO₂ rising up through the relatively permeable path in the cap rock and being emitted back out to the atmosphere. This research proposes a mechanism of CO₂-in-brine emulsion stabilization by surface-coated nanoparticles as a potential cure for these problems. This mechanism is studied in detail by conducting a series of core floods to investigate the interactions between nanoparticles and the surroundings such as fluids and rock surfaces during nanoparticle transport in sedimentary rocks. The experiments presented here use n-octane as a low-pressure analog fluid to supercritical CO₂ as they share several key characteristics. Comparisons of pressure drop and CT images from drainage displacement experiments with and without nanoparticles show that nanoparticle-stabilized emulsions were generated in-situ in highly permeable and homogeneous Boise sandstones tested in this study. Roof snap-off is proposed as the key mechanism for generating the emulsions. The imbibition experiment presents a case where Roof snap-off does not occur. The pressure drop for the control experiment and the nanoparticle experiments confirmed that without Roof snap-off nanoparticles do not affect the dynamics of the displacement except for the viscosity increase of the aqueous phase. However, it was inferred from the saturation profiles and effluent concentration history that nanoparticles were traveling faster than the aqueous phase in which they were dispersed and accumulating at the main displacement front. Inaccessible pore volume is proposed as a mechanism responsible for the accelerated transport of nanoparticles. The single-phase flow experiments demonstrate the accelerated transport of nanoparticles in porous media that was invoked to explain observations during imbibition displacement. During these experiments, tracer and nanoparticles were simultaneously injected into a porous medium and their effluent concentrations were monitored using a UV-Vis detector. The results show that nanoparticles traveled faster than the tracer in Boise and Berea sandstones studied in this research. Two-site model developed by Zhang (2012) was used to fit the data. Simulations suggested that the two-site model could replicate the overall shape of the experimental data when a slug of nanoparticle dispersion was injected, but it was not able to accurately predict the leading edge and the trailing edge of the effluent concentration history, where nanoparticles appeared before tracer due to accelerated transport. To account for the enhanced transport of nanoparticles, a modified two-site model with an acceleration factor, E, is proposed. The resulting fit matched the experimental data better than the original two-site model. / text