Browsing by Author "Zubarev, Eugene"
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Item High-Yield Synthesis and Applications of Anisotropic Gold Nanoparticles(2013-09-16) Vigderman, Leonid; Zubarev, Eugene; Link, Stephan; Kelly, Kevin F.This work will describe research directed towards the synthesis of anisotropic gold nanoparticles as well as their functionalization and biological applications. The thesis will begin by describing a new technique for the high-yield synthesis of gold nanorods using hydroquinone as a reducing agent. This addresses important limitations of the traditional nanorod synthesis including low yield of gold ions conversion to metallic form and inability to produce rods with longitudinal surface plasmon peak above 850 nm. The use of hydroquinone was also found to improve the synthesis of gold nanowires via the nanorod-seed mediated procedure developed in our lab. The thesis will next present the synthesis of novel starfruit-shaped nanorods, mesorods, and nanowires using a modified nanorod-seed mediated procedure. The starfruit particles displayed increased activity as surface-enhanced Raman spectroscopy (SERS) substrates as compared to smooth structures. Next, a method for the functionalization of gold nanorods using a cationic thiol, 16-mercaptohexadecyltrimethylammonium bromide (MTAB), will be described. By using this thiol, we were able to demonstrate the complete removal of toxic surfactant from the nanorods and were also able to precisely quantify the grafting density of thiol molecules on the nanorod surface through a combination of several analytical techniques. Finally, this thesis will show that MTAB-functionalized nanorods are nontoxic and can be taken up in extremely high numbers into cancer cells. The thesis will conclude by describing the surprising uptake of larger mesorods and nanowires functionalized with MTAB into cells in high quantities.Item Surface Modification and Self-Assembly of Gold Nanostructures(2012) Manna, Pramit; Zubarev, EugeneThis thesis describes self-assembly and surface modification of gold nanoparticles and nanorods. It begins with an efficient surface functionalization of gold nanoparticles with a liquid crystalline ligand that structurally resembles liquid crystal 5CB. Functionalized gold nanoparticles show increased solubility in liquid crystal compared to their alkanethiolated analogues. Surface modification technique was also applied to detoxify gold nanorods for biological applications. The process involves a ligand exchange step where cytotoxic CT AB bilayer of gold nanorods was replaced by thiolated CTAB. Covalent nature of gold-sulfur bond allows for the complete removal of CTAB via centrifugation. Functionalized gold nanorods are virtually non-toxic and they show efficient cellular uptake by cancer cells. This thesis also describes self-assembly of gold nanoparticles and nanorods into well organized colloidal crystals. Slow precipitation technique was implemented to prepare three dimensional colloidal crystals of alkanethiolated gold nanoparticles. Colloidal crystals of gold nanorods were prepared by evaporation induced self -assembly technique. Additionally, orientation of nanorods in a colloidal crystal can be altered from side-on to tip-on by controlling the hydrophobicity of the underlying substrate. Our investigation showed that the presence of excess surfactant (CTAB) strongly influences the crystallization process. The shape and size of self assembled structures were also controlled by creating patterned hydrophobic and hydrophilic areas on a substrate. A variety of self assembled structures can be prepared by controlling the dimensions of the patterns. Finally, an efficient synthesis of hybrid cadmium sulfide-gold nanowires was described.Item The development of gold nanoparticle conjugates for the intracellular delivery of paclitaxel(2010) Gibson, Jacob; Zubarev, EugeneThe following work describes our efforts toward the development of a novel gold nanoparticle (AuNP) system capable of the quantitative intracellular delivery of the known chemotherapeutic, paclitaxel. The synthetic strategy employed here features the covalent grafting of multiple drug molecules to the surface of individual gold nanocrystals measuring 2 nm in diameter. This core-shell approach is advantageous as it allows for structural analysis based on traditional analytical techniques and, therefore, definitive confirmation of chemical structure. Perhaps more importantly, the ability to manufacture such a well-defined delivery system allows one to more accurately quantify the amount of bound drug and ultimately, biological activity. While varying the linker structure results in analogous paclitaxel-AuNP conjugates capable of drug release based on endogenous biological processes, a study of the inherent intracellular behavior of these gold nanoparticles led to the discovery of a specific functionality required for efficient drug dissociation under cellular conditions. In fact, results from cell culture experiments reveal this novel delivery system as having comparable toxicity to that of the parent drug, while demonstrating a marked reduction in systemic toxicity in animal models.Item THERAPEUTIC COMPOSITIONS AND METHODS FOR DELIVERY OF ACTIVE AGENTS CLEAVABLY LINKED TO NANOPARTICLES(2015-09-22) Zubarev, Eugene; Gibson, Jacob; Rice University; United States Patent and Trademark OfficeVarious embodiments of the present invention pertain to therapeutic compositions that comprise: (1) an active agent (e.g., paclitaxel); and (2) a nanoparticle (e.g., gold nanoparticle). In such embodiments, the active agent is covalently linked to the nanoparticle through a cleavable linker (e.g., a linker containing a hydrazone species). Other embodiments of the present invention pertain to methods of treating a condition in a subject by administering the above-described therapeutic compositions to the subject.