Giant Magnetoresistive Sensors and Magnetic Labels for Chip-Scale Detection of Immunosorbent Assays

Abstract

The combination of giant magnetoresistive sensors, magnetic labeling strategies, and biomolecule detection is just beginning to be explored. New readout methods and assay formats are necessary for biomolecules detection to flourish. The work presented in this dissertation describes steps toward the creation of a novel detection method for bioassays utilizing giant magnetoresistive sensors as the readout method. The introduction section contains a brief review of some of the current methods of bioassay readout. The theoretical underpinnings of the giant magnetoresistive effect are also discussed. Finally, the more prominent types of giant magnetoresistive sensors are described, as well as their complicated fabrication. Four data chapters follow the introduction; each chapter is presented as a separate manuscript, either already published or soon to be submitted. Chapter 1 presents research efforts toward the production of a bioassay on the surface of a gold-modified GMR sensor. The testing of this methodology involved the capture of goat a-mouse-coated magnetic nanoparticles on the mouse IgG-modified gold surface. The second, third and fourth chapters describe the utilization of a self-referenced sample stick for scanning across the GMR sensor. The sample stick consisted of alternating magnetic reference and bioactive gold addresses. Chapter 2 is concerned with the characterization of both the scanning readout method and the binding and detection of streptavidin-coated magnetic particles to a biotinylated surface. Chapter 3 advances the sample stick readout with the use of the system for detection of a sandwich immunoassay with rabbit IgG proteins. Finally, simultaneous detection of three IgG proteins is demonstrated in Chapter 4. The dissertation is concluded with a brief summary of the research presented and a discussion of the possible future applications and direction of this work.