Browsing by Author "Zubarev, Eugene R"
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Item Fabrication of Organized Anisotropic Materials via Evaporative Self-Assembly(2016-08-31) Derry, Paul J; Zubarev, Eugene RThis thesis describes progress towards the fabrication of macroscopically large, organized structures made from anisotropic nanomaterials using evaporative self-assembly. Chapter 1 is a literature overview of the characteristics and applications of solid gold nanostructures followed by a discussion of several important aspects of nanofabrication and a discussion of self-assembly in the context of extracellular matrix and cell culture. Chapter 2 describes the crystallization of gold nanotriangles (AuNTs) into hexagonal close-packed superlattices by slow evaporation and includes a morphological comparison of the crystallization habits of gold nanorods (AuNRs) and AuNTs. Chapter 3 discusses the use of a passive foaming system constructed from commercially available TEM grids to assemble gold nanowires into regular checkerboard or honeycomb patterns by the collision of two-dimensional foam bubbles formed by the grid. Chapter 4 presents evaporatively self-assembled networks of collagen and chitosan along with a detailed examination of their structure, and spatial scale-up to macroscopically large 150 mm2 networks using custom grids. Finally, Chapter 5 discusses the application of the gold nanowire, collagen, and chitosan networks as cell culture scaffolds for hTERT RPE-1 cells. Laser scanning confocal microscopy and scanning electron microscopy were used to image and characterize the aligned cells and live cell imaging was utilized to show that cellular motility can be controlled by highly ordered collagen networks.Item Polymer- and Bioadditives-Assisted Synthesis and Surface Modification of Anisotropic Gold Nanocrystals(2019-04-15) Requejo Roque, Katherinne I; Zubarev, Eugene RThis thesis presents novel approaches towards the reproducible and scalable syntheses of small anisotropic nanocrystals in high yield utilizing a polymer and small thiolated compounds as shape-directing agents during growth, which enhance the long-term shape stability and colloidal stability after functionalization. Chapter 1 is a literature review of the various methods for producing anisotropic nanoparticles followed by a description of the current growth mechanisms, applications and surface modification strategies to reduce cytotoxicity and improve biocompatibility. Chapter 2 discusses new hydroquinone-assisted seedless and seed-mediated protocols of gold nanorods (AuNRs) by incorporation of nanomolar concentration of distinct molecular weights of poly(vinylpyrrolidone) PVP after growth initiation. Surface chemistry characterization was conducted by attenuated total reflectance (ATR) and X-ray photoelectron spectroscopy (XPS) while nanorods morphological analysis was carried out by high resolution TEM. Chapter 3 describes novel seedless and seeded methods to prepare AuNRs and tune their optical properties to shorter or longer wavelengths by introducing bioadditives or small thiolated molecules such as reduced and oxidized glutathione, L-cysteine, and L-methionine once the growth has been initiated. Chapter 4 presents an improved seed-mediated synthesis of gold nanoprisms (AuNPRs) which enables smaller sizes (edge lengths from 35 to 75 nm) compared to the original protocol, whereas addition of small amounts of PVP during the growth enhances the nanoprisms quality as well as their long-term shape stability. Characterization of AuNPRs thickness ranging from 20 to 35 nm was performed by atomic force microscopy (AFM) and scanning electron microscopy (SEM). The extinction coefficient for different aspect ratio AuNPRs was determined based on inductively coupled plasma-optical emission spectrometry (ICP-OES), TEM and UV-Vis analysis. Finally, Chapter 5 discusses a new hydroquinone-assisted seeded synthesis to achieve small dimensions of monodisperse gold nanoplates (AuNPLs) with edge lengths between 50 and 81 nm by adjusting reagent concentrations and evaluating the use of PVP during the growth stage of the synthesis which increases nanoplate monodispersity and provides their long-term shape stability. The enhanced colloidal stability after functionalization with 11-mercaptoundecyltrimethylammonium bromide (MUTAB) of small anisotropic nanoparticles synthesized with the polymer or bioadditives suggests potential biomedical applications such as radiosensitization and photothermal therapy of cancer.