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Item Study of New Functionalized Nanomaterials for Non-Invasive Point-of-Care Biosensor Devices(North Dakota State University, 2021) Johnson, MichaelEarly disease detection and in-time health monitoring via novel sensing systems is highly demanded for modern medicine and health management. Recent development in nanotechnology and nanomaterials such as functionalized nanostructured metal-oxide semiconductors and newly discovered two-dimensional Ti3C2 MXenes have offered exciting areas of research as nanomaterial-based biomedical sensing devices. In this thesis, two major nanomaterials, KWO for application in diabetes and MXene for cancer management and further improvement of the KWO diabetes sensor, are intensively researched. KWO shows great potential as a breath acetone sensor, which can be utilized to monitor and diagnose diabetes. It also shows the unique ferroelectric property, which allows for a room-temperature sensing operation. Synthesis methods and characterization are done to further the understanding of KWO as an acetone sensor and further improve its capability towards becoming the cornerstone of a handheld biomedical sensor that is non-invasive, portable, and easy-to-use. Continuing, Ti3C2 MXenes are studied and characterized under various synthesis conditions to create both accordion-like structures with varying gap widths, and single-to-few layered nanosheets created by the intercalation of Li+ ions. Additionally, a new sensor based on 2D nanosheets, Ti3C2 MXene, has been designed and used for the sensing response to 8-HOA and PGE2 in lung cancer cells. The preliminary results indicate an important conclusion: this new Ti3C2-based sensor can provide a convenient and simple method for anti-cancer treatment guidance. Finally, a nanocomposite is synthesized using both KWO and Ti3C2 MXenes to improve the acetone sensor’s sensitivity and selectivity by majorly reducing humidity cross-interference.Item Biomimetic Nanoclay Scaffolds for Bone Tissue Engineering(North Dakota State University, 2014) Ambre, Avinash HarishchandraTissue engineering offers a significant potential alternative to conventional methods for rectifying tissue defects by evoking natural regeneration process via interactions between cells and 3D porous scaffolds. Imparting adequate mechanical properties to biodegradable scaffolds for bone tissue engineering is an important challenge and extends from molecular to macroscale. This work focuses on the use of sodium montmorillonite (Na-MMT) to design polymer composite scaffolds having enhanced mechanical properties along with multiple interdependent properties. Materials design beginning at the molecular level was used in which Na-MMT clay was modified with three different unnatural amino acids and further characterized using Fourier Transform Infrared (FTIR) spectroscopy, X-ray diffraction (XRD). Based on improved bicompatibility with human osteoblasts (bone cells) and intermediate increase in d-spacing of MMT clay (shown by XRD), 5-aminovaleric acid modified clay was further used to prepare biopolymer (chitosan-polygalacturonic acid complex) scaffolds. Osteoblast proliferation in biopolymer scaffolds containing 5-aminovaleric acid modified clay was similar to biopolymer scaffolds containing hydroxyapatite (HAP). A novel process based on biomineralization in bone was designed to prepare 5-aminovaleric acid modified clay capable of imparting multiple properties to the scaffolds. Bone-like apatite was mineralized in modified clay and a novel nanoclay-HAP hybrid (in situ HAPclay) was obtained. FTIR spectroscopy indicated a molecular level organic-inorganic association between the intercalated 5-aminovaleric acid and mineralized HAP. Osteoblasts formed clusters on biopolymer composite films prepared with different weight percent compositions of in situ HAPclay. Human MSCs formed mineralized nodules on composite films and mineralized extracellular matrix (ECM) in composite scaffolds without the use of osteogenic supplements. Polycaprolactone (PCL), a synthetic polymer, was used for preparing composites (films and scaffolds) containing in situ HAPclay. Composite films showed significantly improved nanomechanical properties. Human MSCs formed mineralized ECM on films in absence of osteogenic supplements and were able to infiltrate the scaffolds. Atomic force microscopy imaging of mineralized ECM formed on composite films showed similarities in dimensions, arrangement of collagen and apatite with their natural bone counterparts. This work indicates the potential of in situ HAPclay to impart polymeric scaffolds with osteoinductive, osteoconductive abilities and improve their mechanical properties besides emphasizing nanoclays as cell-instructive materials.Item Flexible Nanocomposite Thin Films for Electronic Devices(North Dakota State University, 2019) Alzaid, Meshal MuflehElectronic technology is moving towards flexible, durable, and smaller devices with multifunctional capability. To accelerate this movement, creating materials with outstanding properties is critical. Nanocomposites based on single wall carbon nanotubes (SWCNTs) have received considerable attention because of their unique mechanical and electrical properties. When SWCNTs are formed as a sheet, they provide large contact area and ease of control, especially when incorporated into a flexible format. However, when SWCNT films are adhered to an elastic substrate, there are challenges with their use in flexible electronics, such as a reduction Young’s modulus under deformation. SWCNT films can undergo plastic behavior at even a small strain because individual SWCNTs slide past each other in response to deformation. To address these challenges, a strain-induced elastic buckling instability for mechanical measurements (SIEBIMM) method was used to query SWCNT film mechanics. The buckling wavelength and the film thickness are two main factors that influence the mechanics of nanocomposite thin films adhered to elastomeric substrates. SWCNT films coated with a second nanomaterial, such as a polymer thin film or nanocrystals (NCs), have shown a significant enhancement in elasticity. The studies described in this dissertation demonstrate that polymer thin film can reduce the strain softening of SWCNT films, where both yield strain and Young’s modulus increase with the introduction of SWCNT-polymer layers. Specifically, the films started to exhibit a strong synergy between SWCNT and polymer at a film thickness of around 20 nm, which is attributed to the thickness approaching the characteristic interfacial width between the two materials. Both a ‘passive’ polymer thin film (for example, polystyrene-PS) and an ‘active’ polymer thin film, the conducting polymer poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate)(PEDOT:PSS), were investigated, spanning a bilayer to the bulk limit of SWCNT-polymer multilayers. In addition, ultrathin SWCNT films coated with colloidal NCs have also been investigated. We have utilized two approaches to coat SWCNT films with NCs: Langmuir-Blodgett (LB) and spray coating. Both Si and CdSe nanocrystals showed a roughly two-fold enhancement in film elasticity, which was attributed to an excluded volume effect that prevents the SWCNT rearrangement under an applied strain.Item Silicon Nanocrystals: Optical Properties and Self Assembly(North Dakota State University, 2018) Brown, SamuelSilicon nanocrystal’s (SiNCs) size dependent optical properties and nontoxic nature portend potential applications across a broad range of industries. With any of these applications, a thorough understanding of SiNC photophysics is desirable to tune their optical properties while optimizing quantum yield. However, a detailed understanding of the photoluminescence (PL) from SiNCs is convoluted by the complexity of the decay mechanisms, including a stretched-exponential relaxation and the presence of both nanosecond and microsecond decays. In this dissertation, a brief history of semiconductor nanocrystals is given, leading up to the first discovery of room temperature PL in SiNCs. This is then followed by an introduction to the various nanocrystal synthetic schemes and a discussion of quantum dot photophysics in general. Three different studies on the PL from SiNCs are then presented. In the first study, the stretched nature of the time dependent PL is analyzed via chromatically-resolved and full-spectrum PL decay measurements. The second study analyzes the size dependence of the bimodal PL decay, where the amplitude of the nanosecond and microsecond decay are related to nanocrystal size, while the third project analyzes the temperature and microstructure dependencies of the PL from SiNC solids. After an indepth look at the PL from SiNCs, this report examines preliminary results of SiNC and silver nanocrystal self-assembly. When compared to metal and metal chalcogenide nanoparticles, there is a dearth of literature on the self-assembly of SiNCs. To understand these phenomena, we analyze the size dependent ability of SiNCs to form a ‘superlattice’ and compare this with silver nanocrystals. Although the results on self-assembly are still somewhat preliminary, it appears that factors such as SiNC concentration and size dispersity play a key role in SiNC self-assembly, while suggesting intrinsic differences between the self-assembly of SiNCs and silver nanocrystals. Finally, at the end of this dissertation, a corollary project is presented on the computational analysis of fluorescent silver nanoclusters (AgNCs). Due to their small size and non-toxic nature, AgNCs are an ideal fluorophore for biological systems, yet there is a limited understanding of their photophysics, which is the focus of this part of the dissertation.Item Dynamic 3D In Vitro Bone Metastatic Testbeds for Prostate and Breast Cancer(North Dakota State University, 2022) Jasuja, HaneeshMetastatic prostate cancer spreads preferentially to the bone, causing skeletal complications associated with significant morbidity and a poor prognosis, despite current therapeutic approaches. Increasing evidence suggests the synergistic role of biochemical and biophysical cues in cancer progression at metastases. However, the mechanism underlying the crosstalk between interstitial flow-induced mechanical stimuli and prostate cancer progression in the bone microenvironment remains poorly understood. To this end, we have developed 3D in vitro dynamic models of prostate cancer bone metastasis using perfusion bioreactor and horizontal flow bioreactor to delineate the role of flow-induced shear stress on prostate cancer progression and migration, respectively at metastases. Using a perfusion bioreactor, we observed changes in the expressions of MET biomarkers and the tumoroid morphologies of prostate cancer cells under dynamic culture. Evaluation of cell adhesion proteins indicated that the altered cancer cell morphologies resulted from the constant force pulling due to increased E-cadherin and FAK proteins under shear stress. Using a horizontal flow bioreactor, we demonstrated that the percent cell migration rate of prostate cancer cells was increased in the presence of bone under dynamic conditions. The results showed that interstitial fluid flow did not alter the CXCR4 level, but bone upregulated CXCR4 levels, leading to increased MMP-9 levels. In addition, both αvβ3 integrins and MMP-9 levels were upregulated by fluid flow conditions, contributing to an increased migration rate under dynamic conditions. Breast cancer cells also tend to preferentially disseminate to bone and colonize within the remodeling bone site to cause bone metastases. We have previously developed a 3D in vitro breast cancer bone metastasis model using hMSCs and commercial breast cancer cells (MCF-7 and MDAMB231), recapitulating late-stage breast cancer metastasis to bone. In the present study, we have validated our model using patient-derived breast cancer cell lines- NT013 and NT023, exhibiting hormone-positive and triple-negative characteristics, respectively that showed MET and formed tumors in the presence of bone. In addition, the results showed ET-1 (NT013) and DKK-1 (NT023) mediated stimulation and abrogation of the osteogenesis via Wnt/β catenin pathway, in line with our previous results with MCF-7 and MDAMB231 cell lines.Item The Development, Characterization and Testing of Mg-rich Primers(North Dakota State University, 2012) Battocchi, DanteAluminum alloys are widely used in aircraft industry for their strength and light weight. Those alloys that are hardened by precipitation, especially the Copper-rich of the 2000 series, are prone to corrosion and are protected against it using chromate containing coatings. The primary component of these coating systems is Chromium 6+ (CrVI) that has been found to be very toxic in the environment and carcinogenic, toxic and mutagenic in humans. The Mg-rich primer development is the result of a successful multi-year project funded by the US Air-force with its objective the replacement of coatings based on CrVI with a class of coatings less toxic and with comparable protective performances. The Mg rich primer fulfilled the USAF requirements and it is currently undergoing commercial and military qualifications testing. The use of Mg as one of the active pigments in coatings allows the primer to protect the underlying Al sacrificially, not considered possible for this substrate until now. Mg is anodic to most of the other structural metals and when particulate Mg became available commercially, the concept of the primer was first developed by analogy to Zn-rich coatings for steel. When Mg and Al are in contact and immersed in a corrosive environment, magnesium corrodes preferentially and protects the aluminum.Item Lattice Gases with Molecular Dynamics Collision Operator(North Dakota State University, 2018) Parsa, Mohammad RezaThe purpose of this dissertation is to provide a direct microscopic underpinning for lattice Boltzmann (and lattice gas) methods. Lattice gases are idealized discrete models that conserve mass and momentum. These conservation laws imply, through the formalism of kinetic theory, that on a macroscopic scale these methods recover the continuity and Navier-Stokes equations. As part of the kinetic theory approach, an ensemble average of the lattice gas is taken leading to a lattice Boltzmann equation. These lattice Boltzmann equations can be implemented directly leading to the new how ubiquitous lattice Boltzmann methods. In this dissertation we step away from justifying lattice Boltzmann methods and the ability of recovering suitable macroscopic equations. Rather, their correspondence to coarse-grained Molecular Dynamics simulations is examine and can be cast in the form of a lattice gas evolution equation. We call this lattice gas the Molecular Dynamic Lattice Gas (MDLG). We use this MDLG to derive the exact formulation for lattice Boltzmann equilibrium distributions, relaxation parameters, and fluctuating properties.Item Laser-Assisted Advanced Assembly for MEMS Fabrication(North Dakota State University, 2014) Atanasov, Yuriy AndreevMicro Electro-Mechanical Systems (MEMS) are currently fabricated using methods originally designed for manufacturing semiconductor devices, using minimum if any assembly at all. The inherited limitations of this approach narrow the materials that can be employed and reduce the design complexity, imposing limitations on MEMS functionality. The proposed Laser-Assisted Advanced Assembly (LA3) method solves these problems by first fabricating components followed by assembly of a MEMS device. Components are micro-machined using a laser or by photolithography followed by wet/dry etching out of any material available in a thin sheet form. A wide range of materials can be utilized, including biocompatible metals, ceramics, polymers, composites, semiconductors, and materials with special properties such as memory shape alloys, thermoelectric, ferromagnetic, piezoelectric, and more. The approach proposed allows enhancing the structural and mechanical properties of the starting materials through heat treatment, tribological coatings, surface modifications, bio-functionalization, and more, a limited, even unavailable possibility with existing methods. Components are transferred to the substrate for assembly using the thermo-mechanical Selective Laser Assisted Die Transfer (tmSLADT) mechanism for microchips assembly, already demonstrated by our team. Therefore, the mechanical and electronic part of the MEMS can be fabricated using the same equipment/method. The viability of the Laser-Assisted Advanced Assembly technique for MEMS is demonstrated by fabricating magnetic switches for embedding in a conductive carbon-fiber metamaterial for use in an Electromagnetic-Responsive Mobile Cyber-Physical System (E-RMCPS), which is expected to improve the wireless communication system efficiency within a battery-powered device.Item Manipulation and Isolation of Biomolecules Using Dielectrophoretic and Hydrodynamic Methods(North Dakota State University, 2021) Oh, MyungkeunNovel particle manipulation techniques are developed to separate, isolate, and control a wide range biomolecules from DNA to cells in complex solution such as whole blood. First, we show that integrating an insulating tip with dielectrophoresis allows us to trap, carry, reposition, and relocate nanoscale objects, which can be used as molecular tweezers without fouling, electrolysis, and joule heating issues associated with conventional dielectrophoretic methods. In addition, we find that two theoretical force calculations (Clausius-Mossotti model and counter ion fluctuation model) result in a factor of 2-40 difference, but the magnitude of both is 4 orders stronger than the thermal force, which is strong enough to manipulate objects in the medium. Second, we perform sedimentation and size-based particle separation methods in a microfluidic device configuration. Using polydimethylsiloxane and its high gas solubility, we demonstrate a sedimentation-based, blood cell separation method. To further isolate small biomarkers such as exosomes utilizing a deterministic lateral displacement principle, we fabricate nanoscale pillar structures on a silicon wafer using multiple nanolithography processes and explore possibilities for size-dependent particle separation on the device.Item Synthesis and Characterization of Novel Hierarchically Functionalized Carbon Nanofibers for Energy Conversion and Storage Applications(North Dakota State University, 2014) Zhou, ZhengpingAmong various energy conversion and storage devices available in the market, supercapacitors are deemed as an effective, competitive solution to the increasing demand for high-power density energy-storage devices. Yet, supercapacitors usually carry relatively low energy density compared to batteries. Nanostructured electrode materials are expected being able to greatly enhance the electrochemical performance of supercapacitors. This research aims at rational synthesis and electrochemical characterization of novel hierarchically functionalized carbon nanofibers (CNFs) for use as advanced electrode materials of supercapacitors. These novel CNFs [(i.e., graphene-beaded CNFs (G/CNFs) and carbon nanotube (CNT)-grown CNFs (CNT/CNFs)] were successfully synthesized. The unique synthesis routes consist of electrospinning the precursor polymer nanofibers, followed by controlled carbonization, chemical vapor deposition (CVD) for CNT growth, and in situ polymerization for coating nanostructured conducting polymer. These new electrode materials carry the advantages of G/CNFs and CNT/CNFs (e.g., unique nanostructural continuity, large specific surface area, low intrinsic contact electric resistance, etc.) and conducting polymers (e.g., high pseudocapacitance), and therefore show excellent electrochemical performance including high specific capacitance, superior energy and power densities, and excellent cyclability. In addition, this work also provides the experimental study on parameter dependency of conic angle in electrospinning and scalable fabrication of core-shell nanofibers via needleless emulsion electrospinning.
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