Novel methods for in situ characterization of individual micro- and nanoscale magnetic particles
John M. Moreland, Yoshihiro Nakashima, Jacob W. Alldredge, Gary Zabow
New instrumentation is being developed to better understand the in vivo properties of magnetic particles suspended in solution or lodged in tissue. We describe three novel methods with the necessary sensitivity to measure the microscopic magnetic properties of individual magnetic particles and complexes quantitatively. The first method is based on proton NMR of a magnetic particle suspended in water in a microcapillary probe, the second method uses high resolution MRI of water surrounding a magnetic particle, and the third method is based on a susceptometry with a magnetic cantilever that combines magnetic particle imaging (MPI) concepts with probe microscopy. We present models that describe the physical basis for the measurements, estimate sensitivity limitations, and discuss future impacts on the development of magnetic particles for bio imaging and bio assays.