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Thesis (Ph. D.)--University of Chicago, Dept. of Physics, June 2002. / Includes bibliographical references. Also available on the Internet.

Thesis (M.S.) in Biological Engineering--University of Maine, 2008. / Includes vita. Includes bibliographical references (leaves 39-42).

Thesis (Ph.D.)--Murdoch University, 2008. / Thesis submitted to the Faculty of Minerals and Energy. Includes bibliographical references (leaves 271-286)

Polyelectrolytes coated on high surface curvature nanoparticles (NPs) have been prepared and characterized by a variety of solid-state nuclear magnetic resonance (NMR) experiments in order to examine surface interactions, polymer-water association and polymer dynamic properties of layer components. Gold nanoparticles of four nanometers in diameter pre-stabilized by 4-dimethylaminopyridine (DMAP), and silica and neodymium NPs were chosen as substrates for these studies. The high surface to volume ratio provided by such nanoparticles is advantageous for NMR analysis, which requires a high material content for adequate sensitivity. Firstly, poly(styrene sulfonate) was deposited on gold NPs by electrostatic self-assembly where charged polyelectrolytes adsorb onto an oppositely charged substrate. Surface charges on gold NPs were provided by the ligand DMAP that induces a positive charge at the NP surface that is otherwise neutral. Nanoparticle encapsulation by PSS was monitored by the gold surface plasmon absorption band (SPB) which revealed a good stability under assembly conditions where the pH was maintained above the DMAPsoln pKa and for a polymer radius of gyration comparable to the particle radius. An electrostatic association between DMAPbound and PSS, rather than a ligand substitution, was detected by solid state 13C NMR. When a subsequent layer composed of a weak or a strong polycation was added, the stability of the bilayer was found to be dictated by the nature of the multiple, weak interactions of the polymer functional groups (SO3, NH2, N(CH 3)2+Cl-, NH3 +) with the gold surface relative to that of DMAPbound which in turn is influenced by the assembly pH. / A detailed study of the interactions between the polyelectrolytes, stabilizers and substrates was also extended to polyelectrolyte multilayers coated on gold NPs of different dimensions. Limitations in the application of the layer-by-layer self-assembly technique to very small NPs were investigated and strategies to optimize the method were proposed. 1H NMR analysis in the solid state and 2H NMR analysis in solution revealed that water association and film dynamics were closely related to the identity of the capping layer and independent of even/odd layer effects. These results were compared to those obtained for larger NP substrates which revealed many similarities between the two systems. / A study of the parameters that affect the fabrication of Poly(L-lysine) and DNA polyelectrolyte multilayer films was also conducted for both flat and highly curved surfaces. Such polyelectrolyte films coated on nanopartic1es can be considered as potential vectors for gene therapy. Control over DNA loading into films was performed by varying the ionic strength and pH of polyelectrolyte assembly solutions. DNA density, film degradability and transfection efficiency were examined to determine optimal conditions for vector preparation in gene therapy. Finally, the acid-base properties of lanthanide-based nanoparticles of 10 nm of diameter were explored under a wide range of pH conditions. The interactions of the neodymium oxide nanoparticles with the cationic poly(allylamine hydrochloride) and the anionic poly(styrene sulfonate) polymers were investigated by following spectroscopically optical changes in suspension absorbance and visual changes in NP dimensions. Transparancy and efficiency of stabilization were the evaluated criteria for polymers to be considered as potential stabilizing agents for neodymium oxide NPs used in neutrino detection experiments.

The kinetics and mechanism of the place exchange reaction(PER) of alkylthiols with alkylthiol-protected gold nanoparticles(AuNP) are investigated. Using chemically similar alkylthiols it was possible to study the reaction in the absence of perturbing factors, enabling detailed mechanistic and kinetic studies to be explored. It is found that the reactions are zero order in incoming ligand and overall follow a second order diffusion limited Langmuir rate law. In the case where there is little chemical distinction between the incoming and capping ligands, the reactions proceed to an endpoint consistent with a Keq=1. The rate of the reaction is dependent on the chain length of the capping ligand and the AuNP core size. The related dialkyldisulphide for-alkylthiol AuNP exchange reaction is consistent with the same rate law and also proceeds to a well-defined endpoint. However, the rate constant is 20-fold less than the alkylthiol case. These results lead to a convergent model of PERs where the rate limiting process involves both incoming and outgoing ligands, with diffusion of the incoming ligand to the AuNP surface as the major controlling factor of the reaction rate.

Thesis (M.S.)--West Virginia University, 2000. / Title from document title page. Document formatted into pages; contains xi, 81 p. : ill. (some col.). Vita. Includes abstract. Includes bibliographical references.

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