Doctor of Philosophy, The Ohio State University, 2020, Biophysics

Control, and the degree thereof, is a critical factor to characterize for utilizing any technology. As the field of nanotechnology has progressed, the wonderful potential of technologies on the molecular scale have been held back by the difficulty in controlling the precise arrangement and interactions between molecules to create objects with desired properties and functions. The rise of DNA nanotechnology has provided a path to fully realize the potential of nanotechnology through the programmable self-assembly of DNA strands into complex geometries. Specifically, the more recently developed technology known as DNA origami offers a means to create nanoscale structures or mechanisms with nearly any imaginable geometry and with sub-nanometer precision. This thesis focuses on exploring methods for controlling DNA origami on multiple scales. Initially, this thesis will discuss methods for controlling the self-assembly of DNA origami, which can be used to form multiple nanostructures simultaneously from a complex mixture. The relative strengths of self-assembly reactions help illuminate how such processes can be so efficient in simpler contexts. We show that, not only is it possible to fold multiple nanostructures in a single pot but also that the relative yields of each structure can be tuned. We find that the kinetics of folding for small regions of a structure is a dominant factor in these yields. The intermediate portion of this thesis will discuss methods for control of dynamic DNA origami mechanisms. We develop a highly tunable control scheme combining gold nanoparticles and DNA origami hinge mechanisms which is rapid, robust, and repeatable without the need for material additives. We achieve an advancement over previously demonstrated control schemes by reducing the actuation times to the seconds timescale using temperature jump assays. We can more quickly control the hybridization of tunable latching strands compared to strand displacements methods and more re (open full item for complete abstract)

Committee: Carlos Castro Dr. (Advisor); Jessica Winter Dr. (Committee Member); Michael Poirier Dr. (Committee Member); Ezekiel Johnston-Halperin Dr. (Committee Member) Subjects: Biophysics

Master of Science, The Ohio State University, 2015, Mechanical Engineering

Scaffolded DNA origami has been used to construct objects with complex three-dimensional geometries via molecular self-assembly to create functional nanoscale devices in the 10-100 nm size range. The production of static DNA origami structures is well documented. Only a few designed DNA nanostructures utilize structural dynamics to achieve functionality. In contrast, there has been an emergence of work showing the functionalization of DNA nanostructures through the incorporation of functional molecules or nanoparticles. This work expands the scope of DNA origami applications by incorporating dynamic functional molecules to control dynamic components of DNA origami structures. An in depth investigation into controlling the dynamic motion of a DNA origami hinge through the integration of a transcription repressor protein is the main focus of this thesis. Investigation into the attachment of other nanoscale functional molecules to enable control over nanoscale DNA origami designs is also performed as a proof of concept. This work sets a foundation to create useful dynamic tools to explore complex nanoscale systems.

Committee: Carlos Castro Dr. (Advisor); Michael Poirier Dr. (Committee Member); Jonathan Song Dr. (Committee Member) Subjects: Biomedical Engineering; Engineering; Mechanical Engineering; Mechanics

Master of Science, The Ohio State University, 2006, Graduate School

Committee: Not Provided (Other) Subjects:

Master of Science, The Ohio State University, 2005, Graduate School

Committee: Not Provided (Other) Subjects:

Doctor of Philosophy, The Ohio State University, 2023, Biophysics

Most biomolecular systems are dependent on a complex interplay of forces and modern force spectroscopy techniques provide means of interrogating these forces. These techniques, however, are not optimized for studies in constrained or crowded environments as they typically require micron-scale beads in the case of magnetic or optical tweezers, or direct attachment to a cantilever in the case of atomic force microscopy. I implemented a nanoscale force-sensing device using DNA origami which is highly customizable in geometry, functionalization, and mechanical properties. The device, referred to as the NanoDyn, functions as a binary (open or closed) force sensor that undergoes a structural transition under an external force. The transition force is tuned with minor alterations of 1 to 3 DNA oligonucleotides and spans tens of picoNewtons (pN). This actuation of the NanoDyn is reversible and the design parameters strongly influence the efficiency of resetting the initial state, with higher stability devices (≳10 pN) resetting more reliably during repeated force-loading cycles. Finally, I show that the opening force can be adjusted in real time by the addition of a single DNA oligonucleotide. These results establish the NanoDyn as a versatile force sensor and provide fundamental insights into how design parameters modulate mechanical and dynamic properties. In a secondary study in collaboration with Johnston-Halperin Lab and Winter Lab, we demonstrate an alternate approach to triggering of DNA base pair release by means of an optical trigger. Gold nanoparticles conjugated to short single stranded DNA oligonucleotides were used as a bridging component for two DNA tethers. We showed that the presence of the gold nanoparticle conferred a means of achieving localized surface plasmon resonance resulting in local heating of the environment. This heating resulted in an increased probability that the DNA linkage adjacent to the gold surface was disrupted. These results are a s (open full item for complete abstract)

Committee: Michael Poirier (Advisor); Carlos Castro (Committee Member); Ralf Bundschuh (Committee Member); Ezekiel Johnston-Halperin (Committee Member) Subjects: Biophysics

Doctor of Philosophy, The Ohio State University, 2023, Biomedical Engineering

Micro- and nanoscale technologies can be engineered to modulate the biochemical cues expressed by adipose tissue, thereby influencing their fate and reprogramming cascade. By leveraging these revolutionary platforms, regenerative therapies can be tailored to the unmet specific needs of patients, amplifying controlled tissue repair, wound healing, and immunomodulation. Adipose tissue-related abnormalities are characteristic of a disease state but engineering of in vitro or in vivo models can be an optimistic avenue to study, explore, and mitigate such irregularity. This could potentially be achieved by mimicking the surface energy and topography of the extracellular matrix (ECM). The presented research highlights promising micro/nanotechnology-based contrivances for augmenting adipose tissue-related cellular and reconstructive therapies. Micro/nanotechnology-based platforms hold immense, yet still untapped potential of adipose tissue-derived stem cells to advance personalized treatments. Thus, the technologies described here in the research and their future derivatives could usher in a new era of regenerative medicine by lending intelligent solutions for more effective patient outcomes. The first chapter therefore provides an overview of adipose tissues intricacies and how micro- and nanotechnology can empower our understanding of the same to perform in-situ cell transformation or develop biomaterials which could bolster cellular microenvironment. The second chapter introduces promising direct reprogramming of one cell to another cell type using implantable micro- and nano-channel based gene reprogramming therapy (TNT) device. Such a device offers cellular reprogramming with precision and can transform a fibroblast into brown adipose tissue. The third chapter focusses on a different route using injectable electrospun biopolymer for tissue reconstructive purposes. The last chapter brings a holistic viewpoint highlighting the potential of micro/nanotechnologies fo (open full item for complete abstract)

Committee: Daniel Gallego Perez (Advisor); Derek Hansford (Committee Member); Natalia Higuita Castro (Committee Member); Kristin Stanford (Committee Member) Subjects: Biomedical Engineering; Genetics; Nanoscience; Nanotechnology; Neurosciences

Doctor of Philosophy, The Ohio State University, 2023, Chemical Engineering

DNA is commonly envisioned as the double stranded structure that encodes genetic information, but the specific binding pattern seen between the bases also makes DNA a highly specific building material. DNA nanostructures come in a variety of forms, such as tiles, wireframes, and scaffolded origami. Tile-based structures originated as cross-shaped, synthetic Holliday junctions designed by Seeman that were used for building 2D lattices from repeating units. Over time, DNA nanostructures have evolved into the more complex scaffolded origami pioneered by Rothemund3. These scaffolded structures were originally designed as 2D static objects that have evolved into dynamic materials with rotational, linear, and angular motion. Applications of DNA nanotechnology could include biosensing, multiplexed imaging, drug delivery, and nanorobotics. These applications seek to take advantage of the reconfiguration, biocompatibility, and functionalization potential of DNA nanostructures. Although DNA origami applications are currently limited by scaling issues, many fundamental studies in the fields of plasmonics and nanorobotics have been conducted. Many of these applications rely on the ability to attach nanoparticles (NPs) and biomolecules to DNA nanostructures. DNA origami-NP integration typically uses complementary single-stranded DNA (ssDNA) handles attached to the NP and DNA nanostructure, respectively, for binding. However, conjugation methods for modifying NPs with ssDNA are often lengthy and require precise salt and pH conditions that may destabilize NP colloids. ssDNA handles are easy to design into DNA origami and allow for precise organization of NPs for studying interactions of multiple particles. It is also possible to change the properties of bound NPs and even the DNA itself through metal growth. Metal growth can be performed from NP seeds or on the surface of the DNA origami, thus eliminating the need for NP binding to study emergent properties. In this work, I (open full item for complete abstract)

Committee: Jessica Winter (Advisor) Subjects: Chemical Engineering

Doctor of Philosophy, The Ohio State University, 2023, Chemical Engineering

DNA nanotechnology, specifically DNA origami, provides a platform that leverages complementary base-pairing to design nanoscale devices with a pre-defined geometry capable of precise motion and controlled mechanical properties. This work seeks to enable direct manipulation of complex higher order DNA nanodevice assemblies using DNA strand displacement and optical traps. Increased complexity of current actuation capabilities in the DNA nanotechnology space provides tools and methods spanning across multiple disciplines in engineering. We developed a 6-bar mechanism capable of shape transformations on the single device and multi-device scale using DNA strand displacement. We have also developed a 12-helix bundle, 4-bar linkage, and 7-bar linkage that are capable of higher order assembly with fluorescent readouts to measure force extension using dual optical trapping. Lastly, this work introduces DNA origami education modules that can be translated to middle school, high school, and undergraduate classrooms to enable a more accessible approach to teaching DNA nanotechnology. Creating bio-based tools for controlling more complex devices serves as a foundation for nano-or micro-scale robotic systems and provides platforms for multiplexing the control of nanomachines or molecular interactions. Translating DNA origami principles to classroom modules also allows for implementation of DNA nanotechnology to nontraditional research institutes.

Committee: Carlos Castro (Advisor); Hai-Jun Su (Committee Member); David Tomasko (Committee Member); Jessica Winter (Committee Member) Subjects: Biomedical Engineering; Chemical Engineering; Educational Technology; Engineering; Mechanical Engineering

Doctor of Philosophy, The Ohio State University, 2023, Mechanical Engineering

DNA origami technology allows for the design and fabrication of biocompatible and 3-D functional nanodevices via molecular self-assembly for various biological applications including cell function regulation, disease therapy and biomolecular detection. Biocompatibility and programmability of DNA molecules lead into the development of complex and functional DNA nanodevices that can work in biological media and living systems. Stability and functionality of DNA nanodevices compared to DNA molecules itself, make it an effective approach for cell modulation and payload delivery. The field of nanomedicine, has developed a path to detect and fight infectious disease using nanomaterials and DNA nanostructures are novel additions to the nanomaterial collection, providing great progress in diagnostics and therapy. Nucleic acids, proteins and whole pathogens are among the viral and bacterial targets which can be detected using DNA nanostructures. In this dissertation, we report four studies on biological applications of DNA origami in detection and modulation of biological cues. We establish the successful incorporation of DNA nanodevices on the cell membrane and report a robust method to monitor live cell interactions with biomolecules in their surrounding environment. Our results establish the integration of live cells with membranes engineered with DNA nanodevices into microfluidic chips as a highly capable biosensor approach to investigate subcellular interactions in physiologically relevant 3-D environments under controlled biomolecular transport. Moreover, we propose a novel complex DNA platform for modulating the gap in intercellular junctions and finally establish three DNA nanodevices for the detection of viral and bacterial nucleic acids in human samples. Collectively, the findings of this dissertation establish a foundation on functionality of nanodevices for biological applications.

Committee: Carlos Castro (Advisor); Vishwanath Subramaniam (Committee Member); Comert Kural (Committee Member); Jonathan Song (Committee Member) Subjects: Biomedical Engineering; Biophysics; Mechanical Engineering; Nanotechnology

Master of Science (M.S.), University of Dayton, 2022, Chemistry

Certain molecules (photochromic compounds), when exposed to the light of a specific wavelength, undergo a reversible “isomeric” transformation which leads to reversible changes in some physicochemical properties. Azobenzene derivatives are an example of a photochromic compound that undergoes “cis-trans isomerization” upon irradiation with UV–visible light. Azobenzene derivatives have been previously found to form dynamic photo-responsive supramolecular aggregates. This research aims to further investigate the properties of azobenzene derivatives, and an in-depth understanding of how they form, if at all, dynamic photo-switching aggregates. To evaluate, and study the properties of these molecules, experiments such as solubility, irradiation, and pH experiments were conducted.

Committee: Angela Mammana (Advisor); Vladimir Benin (Committee Member); Justin Biffinger (Committee Member) Subjects: Chemistry

Doctor of Philosophy, The Ohio State University, 2021, Physics

The ability to apply and measure high forces (≥10pN) on the nanometer scale is critical to the ongoing development of nanomedicine, molecular robotics, and the understanding of biological processes such as chromatin condensation, membrane deformation, and molecular motors [1] [2] [3]. Current force spectroscopy techniques rely on micron-sized handles to apply forces, which can limit applications within nanofluidic devices or cellular environments [4]. To overcome these limitations, I used deoxyribonucleic (DNA) origami to self-assemble a nanocaliper, building on previous designs[5] [6]. I characterize the nanocaliper via a short double-stranded (ds)DNA with each strand attached to opposite arms of the device, via device equilibrium state, output force, and dynamics, to understand the effects of sequence, vertex design, and strut length on the device properties. I also produce nucleosomes, hexasomes, and an alternate dsDNA, which were then measured in the device, yielding mechanistic insight into the free energy landscape of each. I measure forces greater than 20 pN applied by the device with a nanometer dynamic range and 1 to 10 pN/nm stiffness. These high performing characteristics which expand the capabilities of existing force spectroscopy techniques as well as those of DNA origami devices.

Committee: Michael Poirier (Advisor); Ralf Bundschuh (Committee Member); Carlos Castro (Committee Member); Ezekiel Johnston-Halperin (Committee Member) Subjects: Biochemistry; Biophysics; Nanoscience; Physics

Doctor of Philosophy, The Ohio State University, 2021, Chemical Engineering

Hemorrhagic shock, the clinical consequence of massive blood loss, is the leading cause of preventable traumatic death. The pursuit of the ideal resuscitation fluid to replace blood in an emergency is ongoing despite over a century of active investigation. While the transfusion of blood sets the clinical bar for other fluids to meet, it suffers from a lack of universal availability especially in prehospital settings. The presently used crystalloid and colloid solutions have never fully met the challenge of reversing hemorrhagic shock and have even slid backwards in their adoption as we learn more about their clinical side effects. The demand for a resuscitation fluid that can provide oxygen to tissue during shock is greater than ever, yet despite numerous attempts with encapsulated and polymerized hemoglobin, no such fluid is available. The purpose of this work is to merge new methods of nanoparticle synthesis with the field of oxygen carriers in order to create a hemoglobin nanoparticle that can carry and deliver oxygen to the body. Protein nanoparticles have been continuing to develop in their complexity and safety as drug delivery vehicles. Many methods of nanoparticle production are not amenable to the large doses which are required of an oxygen carrier due to the designer molecules and filler components used. However, certain nanoparticle manufacturing platforms which rely on self-assembly mechanisms of proteins have an untapped potential for clinical success as oxygen carriers. In this work we investigate the use of two such methods: Desolvation (Chapter 3) and co-precipitation (Chapter 4). Desolvation is implemented with hemoglobin for the first time ever, evolving from its historical use to make albumin drug carriers. Co-precipitation was previously described for making larger microparticles not suitable for intravenous infusion. In this work we illustrate an improved method that creates smaller monodisperse nanoparticles by the incorporation of high- (open full item for complete abstract)

Committee: Andre Palmer PhD (Advisor); Jeffrey Chalmers PhD (Committee Member); Eduardo Reátegui PhD (Committee Member); Nicholas Brunelli PhD (Committee Member) Subjects: Biomedical Engineering; Chemical Engineering; Nanotechnology

Doctor of Philosophy, The Ohio State University, 2021, Chemical Engineering

Advances in the discovery of novel nanomaterials and their properties have resulted in an increase in their demand. Nanomaterials are gaining increasing importance in multiple fields including catalysis, biomedicine, and energy storage with their market expected to double in the next two years. These applications call for innovative technologies that can produce nanomaterial at high throughputs such that quality obtained at the bench scale is retained. The properties of nanomaterials are highly dependent on the mixing dynamics of their synthesis process. Macromixing in conventional batch nanomaterial syntheses increases the overall mixing time, leading to variability within batches and a wide particle size distribution. These problems can be circumvented by using micro- and milli-fluidic reactors that provide a small mixing time because of their associated micromixing and mesomixing. This work investigates a continuous jet-mixing milli-fluidic reactor for the scalable synthesis of metal and metal-oxide nanomaterials and attempts to expand its applicability to a variety of synthesis conditions. Initially, liquid-phase nanomaterial synthesis under ambient conditions is demonstrated as proof-of-concept using the jet-mixing reactor. Silver nanoparticles (Ag NPs) are used as the test system because of their ease of synthesis and characterization. It is observed that Ag NPs synthesized using jet-mixing have a particle size distribution narrower by 4.5% and a 20% increase in stability as compared to their batch-synthesized counterpart. The jet-mixing reactor also demonstrates material economy by requiring a capping agent concentration that is four times lower than that required in batch. Whereas Ag NPs can be synthesized under ambient conditions, the flow synthesis of nanomaterials that are air-sensitive or have air-sensitive precursors remains a challenge. The scope of jet-mixing is expanded to such systems by developing a process to incorporate inert conditions for p (open full item for complete abstract)

Committee: Nicholas Brunelli Dr. (Advisor); Jessica Winter Dr. (Committee Member); Stuart Cooper Dr. (Committee Member); Gonur Kaletunc Dr. (Committee Member) Subjects: Chemical Engineering; Materials Science; Nanoscience; Nanotechnology

Doctor of Philosophy, The Ohio State University, 2021, Physics

Here I develop computationally efficient quantitative models to describe the behavior of DNA-based systems. DNA is of fundamental biological importance, and its physical properties have been harnessed for technological applications. My work involves each of these aspects of DNA function, and thus provides broad insight into this important biomolecule. First, I examine how DNA mismaches are repaired in the cell. Protein complexes involved in DNA mismatch repair appear to diffuse along dsDNA in order to locate a hemimethylated incision site via a dissociative mechanism. I study the probability that these complexes locate a given target site via a semi-analytic, Monte Carlo calculation that tracks the association and dissociation of the complexes. I compare such probabilities to those obtained using a non-dissociative diffusive scan, and determine that for experimentally observed diffusion constants, search distances, and search durations in vitro, both search mechanisms are highly efficient for a majority of hemimethylated site distances. I then examine the space of physically realistic diffusion constants, hemimethylated site distances, and association lifetimes and determine the regions in which dissociative searching is more or less efficient than non-dissociative searching. I conclude that the dissociative search mechanism is advantageous in the majority of the physically realistic parameter space, suggesting that the dissociative search mechanism confers an evolutionary advantage. I then turn to synthetic DNA structures, initially focusing on a composite DNA nano-device. In particular, manipulation of temperature can be used to actuate DNA origami nano-hinges containing gold nanoparticles. I develop a physical model of this system that uses partition function analysis of the interaction between the nano-hinge and nanoparticle to predict the probability that the nano-hinge is open at a given temperature. The model agrees well with experimental data and pre (open full item for complete abstract)

Committee: Ralf Bundschuh PhD (Advisor); Carlos Castro PhD (Committee Member); Michael Poirier PhD (Committee Member); Hirata Christopher PhD (Committee Member) Subjects: Biophysics; Nanotechnology; Physics; Polymers; Theoretical Physics

Master of Science, The Ohio State University, 2021, Mechanical Engineering

Scaffolded DNA origami has emerged as a prevalent technique for the design and construction of nanostructures of specific size, geometry, and function. Specifically, this technology enables programming nanostructure functionality by defining structural, mechanical and dynamic properties. Recent advancements have focused on integrating individual dynamic nanostructures to create reconfigurable supramolecular systems. Subsequently, these functional systems can be triggered by biological or environmental inputs to undergo conformational changes capable of reconfiguring other materials, providing measurable readouts, or influencing biological processes. This work aims to expand on dynamic functions by developing a reconfigurable assembly where local conformational changes can be physically communicated to other parts of the assembly through cascaded motion. We have designed a dynamic DNA nanostructure that can be assembled into arrays that can reach length scales ~10-100 times larger than the individual structure. We have demonstrated proof-of-concept for propagating conformational changes across nanodevices. DNA strands specific to one end of the array initiate motion for the “trigger” structure at that end, which in turn propagates motion to a neighboring structure, and so on in a sequential manner. This propagated motion is designed to transmit a signal across large distances. Creating programmable hierarchical assemblies capable of driving directional motion or signal has become a key goal in DNA nanotechnology. These systems could lead to customizable molecular transport systems, programmable circuits, and the catalysis of biochemical reactions.

Committee: Carlos Castro (Advisor); Jonathan Song (Committee Member) Subjects: Mechanical Engineering

Doctor of Philosophy, The Ohio State University, 2020, Mechanical Engineering

Major advances in DNA nanofabrication by the self-assembly process have occurred over the last decade to construct nano-devices for many applications of science and technology. However, advances in design methodology as well as advanced computational design tools have lagged behind, including computer-aided design (CAD) and coarse-grained models. Currently, for the majority of research in DNA nanotechnology, the design process is carried out using a bottom-up manual approach, which requires expertise and limits complexity. Recently developed top-down automated approaches that are limited to select types of static geometries, sacrificing the design flexibility for various applications. In addition, the integration between CAD and coarse-grained models require extra steps and limits the realization of virtual iterative design for engineering DNA assemblies in a robust manner. Here, we establish a versatile CAD tool that integrates top-down design automation with bottom-up control of component geometry and connectivity to build DNA nanomachines with various geometries (solid, shell, wireframe, or combinations), selected mobility (static, 1D, 2D, or 3D motion), large size via multi-structure assemblies. Based on this custom CAD tool, MagicDNA, we proposed a closed-loop integrated framework with MagicDNA and coarse-grained models, which enables the product design pipeline similar to macroscopic engineering (CAD and CAE) into nanoscale DNA assemblies for evaluating design parameters, rapid prototyping and eventually a robust design for experimental characterization and applications. Several structures were further fabricated to validate not only the target geometry but also the motion pathway, which in all cases generally agreed with simulation results. For these nanomachines, thermal fluctuation plays an important role to affect the component geometry and was quantified with hybrid coarse-grained models and kinematic variance analysis to predict the performance of the (open full item for complete abstract)

Committee: Hai-Jun Su (Advisor); Carlos Castro (Advisor); Shen Herman (Committee Member); Cho Hanna (Committee Member) Subjects: Engineering; Nanoscience; Nanotechnology

Master of Science (MS), Bowling Green State University, 2020, Physics

Iron oxide nanoparticles show immense promise in potential applications in the medical field, namely in MRI imaging, drug delivery, and the thermal destruction of cancerous cells. By combining the magnetic properties of iron oxide with the fluorescent or plasmonic properties of other types of nanoparticles, a material useful in an even wider range of medical applications could be developed. By adding free ligands and heat to a solution of nanoparticles, different materials can be fused together into new geometries. This work examines the methods and challenges present when attempting to coalesce iron oxide nanocubes with other nanomaterials. Additionally, this work explores energy transfer in CsPbBr3 nanocrystals. CsPbBr3 perovskite nanocrystals (NC) are highly fluorescent particles known to exhibit long exciton diffusion distances in artificial solids, making it a potential candidate for energy-concentrating applications. The material's high tolerance for defects as well as its low energy disorder lend to its fantastic properties. In this work, several properties of energy transfer, such as average exciton diffusion distance, rate of energy transfer, and probability of diffusion with every energy transfer event were measured and calculated. By measuring the quenching of CsPbBr3 fluorescence in films with the presence of gold nanoparticles in varying ratios, these properties of exciton diffusion could be determined. Most notably, the average exciton diffusion length was determined to be 52nm in I- treated nanocrystals and 71nm in Cl- treated nanocrystals. Additionally, the efficiency of exciton transfer and charge transfer from CsPbBr3 perovskite nanocrystals to CdSe quantum dots was determined as a way of examining potential applications in light energy concentration.

Committee: Mikhail Zamkov Dr. (Advisor); Alexey Zayak Dr. (Committee Member); Lianfeng Sun Dr. (Committee Member) Subjects: Materials Science; Nanoscience; Physics

PhD, University of Cincinnati, 2019, Medicine: Cancer and Cell Biology

Breast cancer is a leading cause of cancer-related deaths among women worldwide, with an estimated 268,000 new diagnoses and roughly 40,000 deaths occurring in the U.S. alone in the year 2019. Importantly, while breast cancers are categorized into distinct subtypes to dictate which treatment strategy to take, a key indicator of a patient's prognosis is whether or not the cancer has metastasized to distant organs. It is typically not the formation of the primary tumor, but the spread or metastasis of tumor cells that leads to patient mortality, and there is no cure for metastatic breast cancer once it occurs. Nearly two-thirds of all breast cancers express estrogen receptor (ER), and recent research in our laboratory has identified a key role for ER-coactivator Mediator Subunit 1 (MED1) and its two LxxLL motifs in HER2-mediated tumor onset, growth and lung metastasis. Herein, this thesis describes our work to isolate a pool of RNA aptamers that bind to MED1s LxxLL motifs to disrupt the ER/MED1 interaction. One such top RNA aptamer candidate, labeled MED1SP, was capable of selectively disrupting the ER/MED1 interaction while not affecting other ER coactivators like SRC and PGC1-ß. To deliver this MED1SP aptamer to breast cancer cells in vivo, we further incorporated MED1SP into a pRNA nanoparticle delivery system harboring a 3-way junction (3WJ) motif scaffold and a HER2-targeting RNA aptamer. The resultant pRNA-HER2-MED1SP nanoparticles were highly stable, and capable of being successfully delivered to and taken up by HER2-expressing breast cancer cells, where they significantly disrupted cell viability, ER-reporter and –endogenous gene expression, and migration and invasion capabilities. Importantly, when administered into orthotopic xenograft mouse models by I.V. injection, these nanoparticles specifically targeted orthotopically xenografted HER2-expressing tumors, where they dramatically decreased both tumor growth and lung metastasis, with no accumulation or hist (open full item for complete abstract)

Committee: Xiaoting Zhang Ph.D. (Committee Chair); Zalfa Abdelmalek Ph.D. (Committee Member); Jiajie Diao Ph.D. (Committee Member); Jun-Lin Guan Ph.D. (Committee Member); Elyse Lower M.D. (Committee Member) Subjects: Oncology

Doctor of Philosophy, The Ohio State University, 2019, Mechanical Engineering

Nanotechnology has had a profound impact on our daily lives and society over the past few decades. The scale of technological advances and breakthrough solutions provided by nanotechnology is owed to our increasing ability to create and characterize nanostructures and nanosystems with a great degree of control, enabling scientist to exploit nanomaterials for commercial applications that benefit our daily lives and society. Measurement of nano-scale phenomena continues to be a research area of growing interest, and while significant headway has been made, new technologies are needed for continued progress in this emerging field. Atomic force microscopy (AFM) has revolutionized the scientific world by providing researches with a unique method to study surfaces at the sub nanometer level. Since its advent in 1986, the capabilities of AFM have advanced beyond topography imaging, paving the way for multi-modal techniques capable of simultaneously probing surface topography and various material properties. While such advancements have been pivotal toward understanding complex nanoscale material behaviors, many multi-modal AFM techniques still suffer from artifacts that hinder precise analysis of nanoscale properties. These artifacts typically stem from the fundamental design of a conventional AFM cantilever system. In this dissertation, I have introduced a new AFM cantilever design, namely, an inner-paddled cantilever, and studied its performance in multi-modal AFM. The new design consists of an inner-paddle in the form of a silicon nanomembrane integrated to a base-cantilever system. The considerable discrepancy between the structural parameters of the inner-paddle and base-cantilever is an important feature of this two-field design, which allows both structures to vibrate like a system of two-coupled oscillators having in-phase and out-of-phase vibration modes. The inner-paddled cantilever proved to be ideal for functional AFM imaging based on contact resonance, (open full item for complete abstract)

Committee: Hanna Cho Professor (Advisor); Gunjan Agarwal Professor (Committee Member); David Hoelzle Professor (Committee Member); Chia-Hsiang Menq Professor (Committee Member) Subjects: Mechanical Engineering; Nanotechnology

Doctor of Philosophy, The Ohio State University, 2019, Ohio State University Nutrition

Diabetes mellitus (DM) is a global health problem resulting in 2.2 million yearly deaths by DM-related complications. Insulin, for the past century, has been indispensable for the treatment of both type 1 DM and advanced stages of type 2 DM. However, insulin has relatively low efficacy in the central nervous system (CNS). Currently, DM leads to cognitive learning deficits in children as well as an increased risk of Alzheimer's disease in adults. There is a critical need for the development of a new strategy to improve the efficacy of glucose regulation that will prevent CNS-related complications of DM. Nanotechnology could provide a comprehensive platform for the improvement of insulin efficacy and delivery. Dr. Parquette (OSU) has developed a method to produce nanostructures using amino acid compounds (AACs) with and without various side chains; however, these compounds have not been used for treatment of DM. I anticipated that positively-charged AAC nanostructures could potentially bind negatively charged insulin, protect it from cleavage, and extend its interaction with the insulin receptor (InsR). The aim of my dissertation is to investigate AAC interaction with insulin and its effect on systemic glucose uptake and CNS complications. My overall hypothesis was that candidate AAC improves whole-body glucose uptake and prevents neurological complications in mouse models of DM. The structure-function comparison was performed between two AAC compounds with similarly positively charged lysine backbones that either assemble into nanofibers (AAC2) or lack this ability (AAC6). Zeta potential and microbalance techniques showed a stable binding only between AAC2 nanofibers and insulin, suggesting that this nanofiber structure is critical for the interaction with insulin. Next, I tested cytotoxicity in a range of nanostructures (AAC1-3) using a lactate dehydrogenase activity assay and subsequently excluded cytotoxic AAC3. Then, I compared glucose uptake induction bet (open full item for complete abstract)

Committee: Ouliana Ziouzenkova (Advisor); Martha Belury (Committee Member); Lee Kichoon (Committee Member); Parquette Jon (Committee Member) Subjects: Endocrinology; Nanoscience; Nanotechnology; Neurosciences; Nutrition