Metal particles for bioanalysis: Optical properties and bioassay development

This work has focused on gaining a fundamental understanding of the factors that affect the efficiency of biomolecular recognition events during the presence of a metal particle as well as an investigation of the optical properties of rod-shaped striped metallic particles as a function of particle diameter.; Chapter 2 describes the use of colloidal Au nanoparticles as platforms for the enzymatic extension of particle-bound primers. Hybridization efficiencies were determined for three linker lengths to both a complementary solution template and a long template that was used in extension reactions. In all cases, the hybridization of the long template was less efficient than for the short template. Changes in primer:template ratios were also investigated for efficiency of hybridization. It was determined that for short linkers, hybridization efficiency was strongly dependent on primer coverage, while for the longest linker used it was less dependent. Extension efficiencies for the three primers were also investigated. It was determined that extension efficiencies as high as 100% could be obtained for the longest linker used. Chapter 3 describes the use of striped metallic particles as platforms for the development of both protein and DNA based assays. These striped metal particles represent a fundamentally new way of encoding tags for multiplexed bioanalysis. Striping patterns are generated by the sequential electrochemical deposition of metal salts into the pores of alumina membrane templates. Particle striping pattern is demonstrated based on the differential reflectivity of adjacent metal stripes as viewed in a conventional optical microscope. The potential to generate and readout a large number of unique patterns is discussed. Both immunoassays and oligonucleotide assays are developed using fluorescence microscopy.; Finally, chapter 4 investigates the optical properties of striped particles from chapter 3 in more detail by optical microscopy, FE-SEM, and absorbance spectroscopy. These large diameter rods were found to closely follow bulk reflectance data. While it is demonstrated that as many as four metals in one rod can be differentiated based on their reflectivities, up to three can be read reliably. This suggests the ability to generate a large number tags for bioanalysis. Although the large diameter particles were found to agree well with bulk reflectance data, they were also found to have nanoparticle-like behavior. (Abstract shortened by UMI.)...