This thesis describes the study of a variety of nanoscale materials and the development of novel synthetic strategies for their production. While the focus and bulk of this study have been directed specifically at subwavelength lithography, a significant portion of this thesis research involves nanoparticle synthesis, characterization, and functionalization. Put in very simple terms, optical lithography is a process where a beam of light, focused in a specific pattern, is used to generate a physical pattern on a solid substrate. This technology forms the basis for almost all microchip production in the world at the present time. As demand for faster and more powerful chips increases, the need to further miniaturize the patterns while minimizing cost has become very important. Multiple photochemical systems were developed in the search for non-reciprocal photochemistry at 193 nm to increase the resolution of lithographic processes at that wavelength. One approach, based on anthracene sensitization of sulfonium salts for acid generation, used photochemically reversible 4+4 aromatic cycloaddition reactions to introduce the non-linear photochemistry. A second approach took advantage of the photochemistry of N-methylphenothiazine and provided the first true example of a lithographically-relevant multi-photon acid generating process. Since all of the systems we studied used sulfonium salts as the acid generating species, we also looked at the photochemistry of the salts themselves. We evaluated the structural effects of the salts on their direct photochemistry and the implications for sensitized multi-photon photochemistry. We found that the identity of the anion plays a significant role in both processes and propose a new photochemical mechanism for acid generation that involves a charge transfer excitation process. We also describe the synthesis and characterization of novel fluorescent silver nanoparticles, both in solution and polymer films. We show that the fluorescent images can be patterned easily and preliminary results show that photolithography based on nanoparticle formation may be possible. This latter approach could provide a facile route to nanoparticle-embedded functional materials. This work with nanoparticles was inspired partly by earlier work, also presented herein, on semiconductor nanoparticles and their interactions with disulfide ligands.

Nanomaterials have become a popular topic of research over the years because of their many important applications. It can be a challenge to stabilize the particles at a nanometer size, while having control over their surface features. Copper nanoparticles were synthesized photochemically using a photogenerated radical allowing spatial and temporal control over their formation. The synthesis was affected by the stabilizers used, which changed the size, dispersity, rate of formation, and oxidation rate. Copper nanoparticles suffer from their fast oxidation in air, so copper-silver bimetallic nanoparticles were synthesized in attempts to overcome the oxidation of copper nanoparticles. Bimetallic nanoparticles were synthesized, but preventing the oxidation of the copper nanoparticles proved difficult. One important application of nanoparticles that was explored here is in catalyzing organic reactions. Because of the fast oxidation of copper nanoparticles, silver nanoparticles were synthesized photochemically on different supports including TiO2 and hydrotalcite (HTC). Their catalytic efficiency was tested using alcohol oxidations. Different silver nanoparticle shapes (decahedra and plates) were compared with the spheres to see the different catalytic efficiencies.

This thesis describes the photochemical synthesis of silver nano particles, several ways to make these particles as well as control the size and shape of the colloidal particles. Understanding the primary reactions in photochemical nanoparticle formation has lead to important contributions to the overall mechanism of metal nanoparticle synthesis. The size and shape control of the particles is shown to have important implications for the Raman spectrum of surface bound molecules. The particles have also been used in antibacterial properties where it was shown that silver nanoparticles are more antibacterial than the corresponding silver cation, while remaining non-toxic to several common cell lines. The particles were also shown to have some interesting properties that can be exploited in lithography and optoelectronics.

Nanoparticles as novel materials have unique properties due to their incredibly small sizes. Ensembles of nanoparticles not only collect their intrinsic properties but also generate new ones when nanoparticles are sufficiently close. One important way of forming nanostructures entails the assembly of nanoparticle monolayers at liquid interfaces. It is important to understand how the iron oxide nanoparticles transport in a liquid phase and on a liquid/liquid interface and self-assemble into nanostructures over time. As a preliminary research topic before the comprehensive small angle X-ray scattering (SAXS) study, real-time optical reflection of incident p-polarized light near Brewster’s angle shows that after drop-casting iron oxide nanoparticle heptane dispersion on top of a diethylene glycol (DEG) liquid substrate, an iron oxide nanoparticle layer forms at the DEG/heptane interface, and it self-limits to one monolayer even when there are excess nanoparticles dispersed in the upper heptane phase. As is needed for the high time resolution and X-ray exposure minimization requirements of kinetics studies, a new cell with walls at angles is designed to significantly reduce the size of the meniscus, which enables the collection of much larger signals in the SAXS images of ordered arrays of nanoparticles at liquid/air interfaces, along with the observation of extremely high degrees of order. Spatial and temporal SAXS scans show that 8.6 and 11.8 nm iron oxide nanoparticles in heptane drop-cast on top of a heptane layer atop a DEG layer are trapped at the DEG/heptane interface to generally form a single ordered, hexagonally close-packed monolayer, and this occurs long before the heptane evaporates. The morphology of the monolayer is independent of the number of nanoparticles used in the formation process. Many nanoparticles remain dispersed in the heptane after this nanoparticle assembly. Assembly occurs faster than expected from considering only the diffusion of nanoparticles from the drop-cast site to this liquid/liquid interface. And, on the same time scale there is a concomitant decrease in the SAXS form factor from disordered nanoparticles. X-ray beam transmission at different vertical heights characterizes the heptane and DEG bulk and interfacial regions, while monitoring the time dependence of SAXS at and near the DEG/heptane interface gives a clear picture of the evolution of nanoparticle assembly at this liquid/liquid interface. These SAXS observations of self-limited nanoparticle monolayer formation at the DEG/heptane interface are consistent with those using the less direct method of real-time optical reflection monitoring of that interface.

Magister Scientiae (Medical Bioscience) - MSc(MBS) / Recently nanoparticles (NPs) have been introduced and used in combination with therapeutic approaches to develop nanotechnology-enabled medicine. These nanostructures allow for the exploitation of the physiochemical properties which may be beneficial in cancer treatment. The use of NPs in nanomedicine has proven successful in modern chemotherapeutics and has demonstrated promising potential in in vivo and in vitro radiosensitization studies. This is a baseline study aimed to determine the cytotoxic effects of AuNPs for potential radiosensitization analysis. The study analysed the effects of different AuNP sizes (30, 50 and 80nm), concentrations (5, 10 and 15 μg/ml) over various time periods in CHOK1 and A549 cells. AuNPs were characterised by DLS and ZP analysis and showed that particles were moderately polydispersed and moderately to highly stable in charge. The effects on viability and metabolic activity of cells were determined using crystal violet and the WST-1 assay.

Abstract Samson Dada and Dr. Hua Mei, Department of Chemistry, College of Arts and Sciences, East Tennessee State University, Johnson City, TN Our overall research goal is to synthesize a water-soluble, bio-absorbable theranostic nanoparticle (NP) that will improve diagnostic and therapeutic efficacy for cancer. Such theranostic nanoparticles are composed of carbon dots (CDs), conjugated with a targeting agent through a non-cleavable peptide bond; and an anticancer drug Doxorubicin (DOX) using an acid-labile hydrazine linkage for targeted delivery and bio-imaging functions. Recent studies have shown that Carbon dots (CDs) are of interest in biological applications due to their unique properties such as inherent fluorescence, extremely high biocompatibility, and facile synthetic route. The large surface area and multiple surface functionalities make CDs versatile platforms to conjugate with other moieties, including therapeutic agents or targeting agents. The target agents, such as folic acid (FA), are proposed to be permanently linked with CDs to improve the target specificity of the tumor cells. Folic acid is used as a targeting agent as it is a water-soluble, low molecular weight vitamin as it plays an essential role in cell survival and binds with high affinity to the folate receptor (FR) – a membrane-anchored protein that is a cancer biomarker. The multimodal nano-platforms of CDs can also facilitate the delivery the anticancer drugs. The anticancer drug is attached by a cleavable linker that can release the drug inside the tumor cell. We will use the cytotoxic chemotherapeutic agent doxorubicin (DOX) as an example. One series of CDs, FA-CD and FA-CD-DOX, are successfully prepared in the lab. The UV-vis and Fluorescence spectra of the sample was investigated and compared. The concentration of each part in nanoparticles are calculated. The final Drug Load Content (DLC) and Drug Load Efficiency (DLE) are also calculated and compared with the literature. Another series of FA-CD-DOX will be prepared and compared. The characterization of the diagnostic and therapeutic potential of the NP particles will be carried out in the pharmaceutical department.

Hormones play a crucial role in promoting and maintaining many important processes. Progesterone, in particular, is involved in reproductive health, pregnancy maintenance, and hormone-dependent cancers. Many hormonal-based therapeutics are delivered systemically, resulting in side effects for the user or the development of resistance to the delivered agent. This project sought to develop a progesterone-specific nanoparticle-based system for localized modulation of progesterone. The aims included development of the particle, with the use of anti-progesterone antibodies, development of a measurement system to determine relevant, physiological levels of progesterone to validate the proof-of-concept studies, and testing of the particle against the developed progesterone measurement system. The development of the particle progressed in stages, beginning with the generation of oleic acid-coated superparamagnetic iron oxide nanoparticles (SPIONs). Much of the particle development efforts focused on the initial thermal decomposition reaction utilized to develop these SPIONs. Optimization focused on improvement of synthesis parameters to improve yield and reduce particle polydispersity, with reaction modifications resulting in improvement of yield more than threefold, a reduction in particle polydispersity, and an increase in the uniformity of particle morphology. The next phase of particle design was the generation of citric acid-coated SPIONs, followed by addition of polyethylene glycol with active sites for the conjugation of anti-progesterone antibodies. Finally, antibodies were successfully conjugated to the surface of the particles, validated with protein absorbance at 280 nm. Additionally, several standard curves for progesterone, ranging in concentration from 0 to 50 g/mL, with values of the coefficient of determination for the linear curves greater than 0.9 for all the tested methods, were generated. Specifically, standard curves were generated in ethanol, as well as ethanol diluted in both water and phosphate buffered saline to better replicate physiological conditions. All three solutions resulted in linear standard curves for confident determination of the concentration of solutions of progesterone. Finally, the ability of the particles to bind to progesterone was successfully validated using UV absorbance at 241 nm by comparing the progesterone remaining after wash steps for antibody-particles, blank-particles, and the progesterone standard solution. This project resulted in the successful development of anti-progesterone antibody conjugated nanoparticles, validation of the specificity of the particles for progesterone, linear standard curves for progesterone in a variety of solutions, and optimization of the oleic acid SPION synthesis reaction. Future efforts should focus on the detection of progesterone at concentrations below 200 ng/mL, as this was a primary challenge in both the development of the progesterone concentration assay and the testing of the affinity of the particles for progesterone. Future research should focus on the optimization of the antibody-conjugation process to maximize coating density while minimizing loss of unconjugated antibody and further development of the testing conditions to determine the duration of treatment and the strength of the affinity of the particles for progesterone. / 2025-05-24T00:00:00Z

Energy harvesting using ferrofluid in OHP. Characterization of as-synthesized (bare) and surface-modified ferrofluid samples was performed using Fourier transform infrared spectroscopy, dynamic light scattering, X-ray powder diffraction, transmission electron microscopy, and atomic force microscopy. These ferrofluids were tested in a novel oscillating heat pipe set-up was utilized to harvest electricity, demonstrating the concept of ferrofluidic induction. Cobalterrite nanoparticles surface-modified with citric acid demonstrated good magnetic strengths and generated voltages close to those of the as-synthesized ferrofluids while maintaining dispersion. Surface modification of ferrous nanoparticles with SRP. Thermo responsive polymer poly(N-isopropylacrylamide) was successfully grown from the surface of cobalt-zinc ferrite nanoparticles. A dual responsive block copolymer, pH and thermo responsive comprised of poly(itaconic) acid and poly(N-isopropylacrylamide) was successfully polymerized from the surface of ferrous oxide nanoparticles. These composite having magnetic properties along with stimulus can be used in applications such as controlled drug delivery and similar biomedical applications.

Electrolyte interactions with colloidal nanoparticles (NPs) in aqueous solutions have been implicated in a wide range of research and applications. Existing studies on electrolyte interactions with NPs are primarily based on the electrical double layer (EDL) theory. However, the EDL model provides very limited information on how electrolytes directly bind to NPs, electrolyte impact on charge distribution on NPs, and NP morphological modification upon electrolyte binding. Furthermore, the previous reports have mainly focused on either cations or anions binding onto NPs, while the potential cation and anion coadsorption onto NPs and NPacilitated cation-anion interactions remain largely uncharted. Filling these knowledge gaps are critical to enhance the fundamental understanding of interfacial interactions of electrolytes with NPs. Experimental characterization of cations and anions at the solid/liquid interface is a challenging analytical task. In the first study, we demonstrated the first direct experimental evidence of ion pairing on gold nanoparticles (AuNPs) in water by using surface enhanced Raman spectroscopy (SERS) in combination with electrolyte washing. Unlike ion pairing in aqueous solutions where the oppositely charged ions are either in direct contact or separated by a solvation shell, the ion pairing on AuNPs refers to cation and anion coadsorption onto the same NP surface regardless of separation distance. Ion pairing reduces the electrolyte threshold concentration in inducing AuNP aggregation and enhances the competitiveness of electrolyte over neutral molecules in binding to AuNPs. In the second study, we demonstrated that binding, structure, and properties of an ionic species on AuNPs are significantly dependent on the counterion adsorbed on AuNPs. These counterion effects include electrolyte-induced AuNP aggregation and fusion, quantitative cation and anion coadsorption on AuNPs, and SERS spectral distortion induced by the ionic species on AuNP surfaces. In the final study, we proposed that ion pairing as the main mechanism for reducing electrostatic repulsion among organothiolates self-assembled on AuNPs in water by using a series of experimental and computational studies. The work described in this dissertation provides a series of new insights into electrolyte interfacial interactions with AuNPs.

The objective of this research was to study the catalytic graphitization of cellulose fibers coated with iron oxide nanoparticles. Bleached cellulose fibers and iron oxide nanoparticles coated cellulose fibers were pyrolyzed at five elevated temperatures. The crystallographic structures of carbon-encapsulated iron oxide nanoparticles were then investigated by the following techniques: Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD), Raman Spectroscopy, Transmission Electron Microscopy (TEM), and Selected-Area Electron Diffraction (SAED). The graphitization of cellulosic fibers was enhanced by the presence of iron oxide nanoparticles. Moreover, iron oxide nanoparticles deposited on cellulosic fiber samples pyrolyzed above 800°C produced graphitic structures. TEM and XRD were performed to identify and characterize the phase transitions of carbon-encapsulated iron oxide nanoparticles after pyrolysis treatment at four temperatures: 500°C, 800°C, 1000°C, and 1600°C. TEM of samples pyrolyzed at or above 800°C showed resulting units were core-shell structures consisting of dark grains and a light matrix with graphitic structure.