The use of magnetic particles for the labeling of biological molecules is an important technique for studying biological interactions.  Magnetite (Fe3O4) microspheres exhibiting a narrow size distribution were synthesized in batches ranging in size from 100 to 700 nm.  These particles were coated with silica and then functionalized with an organic ligand such as an amino group and/or biotin.  These ligands were used to attach the modified microspheres to a functionalized surface.  Thus, the microspheres were used to measure the non-covalent binding forces of ligand-receptor bonds as detected by force-induced remnant magnetization spectroscopy (FIRMS), which measures the magnetic signal vs. an external mechanical force.  When the mechanical force matches the binding force, the antibody-antigen bonds dissociate, resulting in a reduced magnetic signal because the Brownian motion of the dissociated magnetic microspheres randomizes their magnetic dipoles.  Our synthesized microspheres provide stronger magnetic properties, and thus have the potential of producing better sensitivity in detecting the labeled ligand, as compared to several widely used commercially available magnetic particles.  The morphology of these microparticles were characterized by several techniques.  The magnetic properties were characterized using a vibrating sample magnetometer (VSM) and an atomic magnetometer.  The biological properties were confirmed by fluorescence spectroscopy.  We will discuss the potential applications of the synthesized magnetic microspheres in biomolecular imaging.

Magnetic microspheres designed for molecular sensing using force-induced remnant magnetization spectroscopy

247th National Meeting (2014)

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