In this project a method based on surface plasmon resonance has been developed for determining the concentration of several His-tagged proteins in complex solutions. It showed large dynamic range, no measureable non-specific binding and high sensitivity (with linear range around 0.1–10 μg/ml depending on the proteins). The method showed a low variation when checked on MBP-His during an extended time period. The concentrations of the His-tagged protein in the lysate has also been determined and compared with other alternative methods. This method will later be used to analyse protein concentrations during development and optimization of chromatographic purification process.

Electron-excited surface plasmon resonance (eSPR) is investigated for potential use in biosensors. Optical SPR sensors are commercially available at present and these sensors are extremely sensitive, but have the tendency to be relatively large, expensive, and ignore the potentials of microelectronic technology. By employing the use of various microelectronic and nanotechnology principles, the goal is to eventually design a device that exploits the eSPR phenomenon in order to make a sensor which is siginificantly smaller in size, more robust, and cheaper in cost.

<p>Antithrombin (AT) is one of the most important anticoagulant factors in the blood, and its effects are increased by the interaction with glycosaminoglycans, especially heparin. AT appears in two additional variants, other than the native form, and those variants have antiangiogenic properties and also bind to heparin. AT is found in two distinct isoforms (alfa, beta) where the difference lie in the degree of glycosylation. This project has shown interesting results regarding the dependence of calcium ions on the binding between heparin and antithrombin. The results show that the beta-isoform increases its affinity for heparin in the presence of calcium in contrast to the alfa-isoform, which shows a decrease in the heparin affinity under the same conditions. This project has also given results that after further investigation and development could be used for an improved set-up of the immobilisation of AT variants in a surface plasmon resonance system. The results show that immobilisation of a protein in the reference channel gives a better shielding effect between the negatively charged heparin molecules and the negatively charged dextran matrix. Furthermore a more significant difference was seen between the two heparin moieties used during binding affinity studies, especially for native AT.</p>

Thesis (Ph. D.)--University of Washington, 2003. / Vita. Includes bibliographical references (leaves 198-210).

Thesis (Ph. D.)--University of Washington, 2003. / Vita. Includes bibliographical references (leaves 164-178).

Thesis (Ph. D.)--University of Washington, 2002. / Vita. Includes bibliographical references (leaves 243-262).

Optical molecular imaging has burgeoned into a major field within biomedicine, and technologies that incorporate surface plasmon resonance effects have become a major focus within this field. Plasmon resonance has been defined as the collective oscillation of the conduction band electrons in certain metals (such as gold) in response to an electric field, such as an impinging wave of light. We show that elastic light scattering due to the plasmon resonance of nanometer-sized gold particles makes them powerful tools for optical imaging of epidermal growth factor receptor (EGFR) expression -- a major biomarker for carcinogenesis. Optical technologies in general are poised as cheap, flexible ways to aid in diagnosis and treatment of disease. In addition to supplying a bright, stable optical scattering signal and a convenient conjugation platform for targeting molecules, these materials display a unique behavior termed "plasmon coupling". This term refers to the dramatic optical property changes brought about by the presence of other nearby nanoparticles. These changes include a dramatic red-shifting in their peak plasmon resonance wavelength, as well as a non-linear, per-particle increase in the overall scattered power. We show that such conditions exist in cells and are primarily due to intricate protein trafficking mechanisms as part of the EGFR life-cycle. The observed variations in plasmon coupling can give clues as to the nanoscale organization of these important proteins. In addition, the resulting optical property changes result in a large, molecular-specific contrast enhancement due to the shifting of the resonance closer to the near infrared region, where biological tissues tend to be most transparent. Despite this enhancement, however, many tissues contain large endogenous signals, as well as barriers to delivery of both light and the nanoparticles. As such, we also show an example of a multifaceted approach for further increasing the apparent molecular-specific optical signals in imaging of EGFR expression by using an oscillating magnetic field. This serves to encode the signal from magnetically susceptible plasmonic nanoparticles, making their extraction from the background possible. Overall, the studies presented in this dissertation should serve to stimulate further investigations into a wide variety of technologies, techniques, and applications.

Patterned arrays of metallic nanostructures are commonly used in photonics, electronics, as well as functional materials and biotechnology because of their unique electronic and optical properties. Although great effort has been devoted to the development of nano-patterning techniques in the past decades, there are still existing challenges for nano-fabrication to achieve fine resolution and complex features over macroscopic areas in a reasonable time period. Herein, we devise two versatile patterning strategies, namely indentation colloidal lithography (ICL) and oblique colloidal lithography (OCL), for the stepwise patterning of planar substrates with numerous complex and unique designs. Those strategies combine colloidal self-assembly, imprint molding in conjunction with capillary force lithography and reactive ion etching, all of which are simple and straightforward. Hexagonal arrays of symmetric and nonconcentric gold features are fabricated on glass substrates with highly controllable geometric parameters. The width, size and asymmetry of each surface structure could be tuned down to the ~10 nm level while the scale of the patterned area could exceed 1 cm^(2). Moreover, our technique also leads to the ability to develop an enormous variety of patterns through stepwise amplification of feature types. In particular, some of the features are fabricated for the first time, including target-triangle, hexagram, hexagram-dot and triangle-dot. Distinctive surface plasmon resonance (SPR) properties, such as higher order surface plasmon modes and Fano resonances are both observed from our patterns, which would be highly desired forthe study of plasmonic coupling. In addition, we have demonstrated a surface orientation dependent Raman selectivity on two nano-structures for the first time. Molecular vibrations with opposite symmetries can be selectively enhanced on different substrates. As a demonstration, this property is applied to the odd-even effect of n-alkanethiol self-assembly monolayers (SAMs) on the gold surface. The alternative alternation of the intensity ratios of two vibration pairs have been shown by surface enhanced Raman spectroscopy (SERS) as a function of the number of carbon atoms. The results obtained exhibit high sensitivity and excellent agreement with previous publications.

Thesis (M.S.)--Auburn University, 2006. / Abstract. Vita. Includes bibliographical references.

Thesis (M.Eng.). / Written for the Dept. of Electrical and Computer Engineering. Title from title page of PDF (viewed 2008/04/12). Includes bibliographical references.