| Description |
For the last two decades, our research group has focused on developing nanotechnology-based diagnostic platforms for disease detection. One of our main diagnostic platforms is magnetic immunoassay based on giant magnetoresistance (GMR) readout. Due to high sensitivity and rapid data retrieval of the GMR readout, GMR-based immunoassays enable a low level of rapid detection of disease markers and have the potential for multiplexing (i.e., detecting multiple analytes simultaneously). As part of an effort to develop a GMR-based multiplexing test, this dissertation focuses on the development of magnetic labels for use in magnetic immunoassays. Thus, the body of this dissertation includes: (1) synthesis of magnetic nanoparticles (MNPs) with high magnetic moments; (2) emulsion-based bottom-up assembly approach to design new magnetic materials; (3) surface functionalization of MNPs and biomolecule conjugation for use as magnetic labels; and (4) development of magnetic immunoassays for the detection of potential pancreatic cancer markers using our GMR sensor. Firstly, silica encapsulation of ferrimagnetic nanocubes with high magnetic moments (m) is described. These results not only demonstrate the synthesis of high-m MNPs uniform in size and shape, but also stabilization of the MNPs with high m via silica coating. Secondly, the fabrication of colloidal assembly of MNPs is discussed with the investigation of their magnetic properties. This chapter shows that assembly of MNPs into a larger magnetic bead can not only change their magnetic properties, but also be an efficient way to design new materials for specific applications. Next, surface coating and biomolecule conjugation of the colloidally assembled magnetic beads are investigated to prepare magnetic labels. These results indicate that magnetic labels based on colloidally assembled magnetic beads are superior to commercially available magnetic labels. The last chapter is focused on the development of magnetic immunoassays for the simultaneous detection of pancreatic cancer markers based on our magnetic label and GMR sensor. The results show the potential of a GMR-based diagnostic platform in rapid and sensitive detection of disease marker, as well as multiplexing. With these results, this dissertation aims to the development of magnetic labels for GMR-based magnetic immunoassays towards simultaneous detection of multiple disease markers. |
