Magnetic Force Microscopy of Superparamagnetic Nanoparticles

The use of magnetic force microscopy (MFM) to detect probe–sample interactions from superparamagnetic nanoparticles in vitro in ambient atmospheric conditions is reported here. By using both magnetic and nonmagnetic probes in dynamic lift‐mode imaging and by controlling the direction and magnitude of the external magnetic field applied to the samples, it is possible to detect and identify the presence of superparamagnetic nanoparticles. The experimental results shown here are in agreement with the estimated sensitivity of the MFM technique. The potential and challenges for localizing nanoscale magnetic domains in biological samples is discussed. Detecting nanomagnets: By using external magnetic fields and magnetic atomic force microscopy (MFM) tips, it is possible to identify the dipolar nature of superparamagnetic nanoparticles in ambient air (see figure). These approaches could help localize magnetic deposits in diseased tissues.