Magnetite microspheres and nanospheres are widely used for labeling biomolecules to study ligand-receptor interactions and to achieve molecule-specific detections. However, commonly used commercial magnetic particles have relatively weak magnetic properties, which limit the signal amplitude for detection. This presentation describes the synthesis of magnetite nanospheres (sub-micron sizes) having stronger magnetic properties than the commercial ones and their subsequent applications in probing protein-protein interactions. Three different sizes of the magnetic nanospheres (i.e., diameter 100, 400, and 700 nm) were synthesized and functionalized. Their magnetic properties were at least one order of magnitude stronger than the widely used M280 magnetic particles in overall sample. We demonstrate the application of the magnetite spheres for specific protein detection using the exchange-induced remnant magnetization (EXIRM) technique. This technique relies on the exchange reaction of the targeted protein with the protein-functionalized magnetic spheres because of the higher affinity of the former to the surface-immobilized receptors. The exchange is indicated by a reduced magnetic signal because of the removal of the magnetic nanospheres after their dissociation. The application is shown with protein A binding with different subclasses of immunoglobulin IgG. Further refinement of the synthesis and applications will be discussed.<br/><br/><b>Keywords:</b> Magnetic Particles, Molecule-Specific Detection, Magnetite, Exchange-Induced Remnant Magnetization, Protein Interactions

Synthesis of unusually large magnetic nanospheres and their novel applications in protein detection

251st National Meeting (2016)

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