This research investigates an extension of the glancing angle deposition (GLAD) technique and a biosensing application of films produced by GLAD. The extension to GLAD, called phi-sweep (PS), improves column isolation compared to films grown by traditional GLAD (TG) as well as modifies the column tilt angle, , of the slanted columns according to tan(_{PS}) = tan(_{TG}) cos(), where is the sweep angle. The biosensing application makes use of localized surface plasmon resonance in noble metal GLAD films functionalized with rabbit immunoglobulin G (rIgG) to detect binding of anti-rabbit immunoglobulin G (anti-rIgG) to the films' surface. The extinction peak red-shifts a distance dependent on the concentration of anti-rIgG solution in a manner described by the Langmuir isotherm with a saturation value, _{max}, of 29.4 0.7 nm and a surface confined thermodynamic binding constant, K, of (2.7 0.3)10 M. / Microsystems and Nanodevices

Surface immobilization of probe molecules in surface based assays is a key area of research in the continued development of immunoassay microarrays. Interest continues to grow in microarray based immunoassays given their potential as a high throughput technique for immunodiagnostics. Therefore, it is important to thoroughly study and understand the implications of interfacial chemistry and immobilization conditions on the performance of the assay. This thesis presents a body of work that examines the impact of probe density, interfacial chemistry, and enhancement factors for arrays read with surface plasmon resonance (SPR) imaging. An array of structurally similar Salmonella disaccharides was immobilized at varying densities and the interface formed was thoroughly investigated to determine the properties of the interface. The arrays were then used with SPR imaging to evaluate the binding of an antibody specific for one disaccharide of the three stereoisomers on the array. A dilute disaccharide surface was found to provide optimal antibody binding. Higher densities result in steric hindrance of antibody binding by not allowing the disaccharide to insert into the antibody binding pocket. The role of interfacial chemistry in antibody attachment was studied to determine optimum conditions. The study examined physical adsorption, covalent attachment, and affinity capture. It was found that covalent attachment provided the most stable attachment and resulted in the lowest levels of antigen detection. Both the physical adsorption and affinity capture provided larger antigen binding capacity and therefore more sensitive antigen detection. The covalent attachment was chosen to evaluate an enhanced assay with the incorporation of gold nanoparticles. These particles provided detection limits that were an order of magnitude improved over those excluding the nanoparticles. A novel surface chemistry for antibody immobilization in SPR imaging studies was evaluated. This involved the electrochemical driven formation of mono- to multilayers of diazonium benzoic acid films. The studies showed the ability to control the thickness of the films formed and also the ability of the antibody chips to capture antigen from solution.

Two types of core/shell nanoparticles (CS-NPs) generation based on laser ablation are developed in this study, namely, double pulse laser ablation and laser ablation in colloidal solutions. In addition to the study of the generation mechanism of CS-NPs in each scheme, the optical properties of designed CS-NPs are determined with UV-VIS-NIR spectroscopy and EM field simulation. In the first scheme, which is double pulse laser ablation, two laser beams are fired in a sequence on two adjacent targets with different material. We have successfully demonstrated the generation of Sn/Glass, Zn/Glass, Zn/Si, Ge/Si, and Cu/Zn CS-NPs. Key factors affecting the generation of CS-NPs are (1) surface tensions of the constructing materials affecting the associated Gibbs free energy of CS-NPs, (2) physical properties of selected background gases (i.e., He and Ar), (3) delay time between two laser pulses, and (4) the amount of laser energy. The second scheme examined for the generation of CS-NPs is through laser ablation of solid targets in colloidal solutions. Compared to the double pulse laser ablation, this second approach provides better control of the size and shape of the resulting CS-NPs. Two colloidal solutions, namely, Au and SiO2 colloidal solution are applied in the second scheme. Key factors affecting the formation of CS-NPs with the second scheme and are (a) the adhesion energy between the shell and the core material, (b) the diameter of the core and (c) the laser ablation time and the laser energy. Red shift of absorption peaks are measured in both SiO2/Au and SiO2/Ag colloids compared with pure nanoparticles (NPs). The amount of red-shift is very sensitive to the shell thickness of the CS-NPs. The same red shift is reproduced with the corresponding full wave analysis. The observed red shift can be attributed to the additional surface plasmon resonance at the interface of metal/dielectric of the CS-NPs compared with pure nanoparticles. Through adjusting the material and size combination, the absorption peak of the CS-NPs can be tuned in a limit range around the intrinsic absorption peak of the metal of the CS-NPs. The freedom of adjusting the absorption peak makes CS-NPs is favorable in bio and optical applications.

Diss. (sammanfattning) Linköping : Univ., 2001. / Härtill 6 uppsatser.

Dissertation (Ph.D.)--Auburn University, 2008. / Abstract. Vita. Includes bibliographic references.

Thesis (Ph. D.)--University of Washington, 2006. / Vita. Includes bibliographical references (leaves 114-127).

Thesis (Ph. D.)--University of Washington, 2007. / Vita. Includes bibliographical references (leaves 228-245).

Thesis (Ph. D.)--University of Washington, 2007. / Vita. Includes bibliographical references (leaves 246-276).

Orientador: Valber de Albuquerque Pedrosa / Resumo: O desenvolvimento de novos dispositivos para monitorar o metabolismo celular e o diagnóstico de doenças expandiu as pesquisas com biossensores, que aliados à nanotecnologia possibilitaram a criação de novos elementos com alta sensibilidade de detecção, especificidade e capacidade de multiplexação, mostrando grande potencial para sua aplicabilidade no diagnóstico clínico. O trabalho foi desenvolvido em duas etapas. A primeira, referiu-se no desenvolvimento de uma metodologia para acoplar o aptâmero conjugado com as nanopartículas de ouro sobre o sensor da Ressonância Plasmônica de Superfície (SPR). Foi utilizado MUA para formação das monocamadas auto-organizadas; ativação dos grupos carboxílicos utilizando solução de EDC/NHS e a imobilização do aptâmero conjugado. Após este processo, foram realizadas as injeções de Mucina Epitelial Polimórfica tipo 1 (MUC1). A segunda etapa, consistiu na mesma metodologia de acoplamento do aptâmero, porém substituindo a MUC1 por sobrenadante da linhagem celular LNCaP (células prostáticas tumorais). Desse modo, foi desenvolvida uma metodologia analítica utilizando aptâmeros e biomarcadores para diagnosticar o Câncer de Próstata (PCa) através da SPR. / Mestre

Surface plasmon is the quantized collective oscillation of the free electron gas in a metallic material. By coupling surface plasmons with photons in different nanostructures, researchers have found surface plasmon polaritons (SPP) and localized surface plasmon resonance (LSPR), which are widely adopted in biosensing, single molecule sensing and detection via surface enhanced raman scattering (SERS), photothermal ablation treatments for cancer, optical tagging and detection, strain sensing, metamaterials, and other applications. The overall objective of this dissertation is to investigate both how mechanics impacts the optical properties, and also how optics impacts the mechanical properties of metal nanostructures reversely. Mechanically engineering individual nanostructures(forward coupling) offers the freedom to alter the optical properties with more flexibility and tunability. It is shown that elastic strain can be applied to gold nanowires to reduce the intrinsic losses for subwavelength optical signal processing, leading to an increase of up to 70% in the surface plasmon polariton propagation lengths at resonance frequencies. Apart from strain engineering, defects are another important aspect of mechanically engineering nanoscale materials, whose impacts on the optical properties of metal nanostructures remain unresolved. An atomic electrodynamic model has been derived to demonstrate that those effects are crucial for ultrasmall nanoparticles with characteristic sizes around 2 nm, and can be safely ignored for those larger than about 5 nm due to the important contribution of nanoscale surface effects. Another key focus of this research project (reverse coupling) is to investigate the currently unknown effects that an external optical field has on the mechanical properties of metal nanostructures. Since each atom in the nanostructure acts as a dipole due to induced electron motions, this optical excitation introduces additional dipolar forces that add to the standard mechanical atomic interactions, which could alter the mechanical properties of the nanostructures. Furthermore, it is shown that when linking mechanics with LSPR, because the metal is dispersive, the mechanical behavior or the strength of the nanostructure should be dependent on the frequency of the electromagnetic excitation. To study this phenomenon, a simpler case with an electrostatic field excitation is considered first, and conclusions are reached on how static fields can be used to tune the elasticity of metallic nanostructures with different sizes and axial orientations and surfaces. Then building upon those understandings, studies were carried out in determining the effects of an optical field, specifically at LSPR frequency, on the mechanical properties of metallic nanostructures. It is found that the initial relaxation strain induced by the static field or optical field is the key factor leading to the variations in the stiffness of the metallic nanostructures that are excited by optical fields at the LSPR frequencies.