Magnetic Force Microscopy of Superparamagnetic Nanoparticles

Abstract

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.

Imaging and Characterization of Magnetic Micro- and Nanostructures Using Force Microscopy

“…In most cases these measurements are conducted on iron-oxide-based nanoparticles, which have (due to their nontoxicity) the highest pharmacological relevance. Schreiber et al conducted MFM experiments and simulations of such nanoparticles and concluded that in a conventional MFM setup (using commercially available MFM probe, measuring in air), only nanoparticles larger than 10 nm in diameter can be accessed, a conclusion which triggered several new developments in this field [143]. In 2011, several groups succeeded (by enhancing the measurement sensitivity using modified versions of MFM) in stray-field imaging of single, isolated iron-oxide-based nanoparticles being as small as 5 nm in diameter [145,146].…”

“…This is, for example, useful if the sample exhibits a stable magnetization only in the presence of a polarizing magnetic field (e.g., for superparamagnetic materials) [143][144][145][146] or if the dependence of M sample on externally applied fields should be investigated (e.g., for switching experiments/study of magnetization reversal, for visualizing the movement of domain walls, etc.) [121][122][123][124][125][126][127][128][129][130][131][132][133][134][135][136][137][138][139].…”

“…This field might be generated by a sample magnetization M sample (e.g., by magnetized Weiss domains of a ferromagnetic material [86,88] or by (super)paramagnetic materials, which are magnetized inside an external magnetic field) [143][144][145][146] or equivalently by magnetic moments m sample (e.g., generated by an electrical current or by flux lines within superconductors) [148][149][150] incorporated in the sample (Fig. 13.3).…”

Novel Plasmonic Probes and Smart Superhydrophobic Devices, New Tools for Forthcoming Spectroscopies at the Nanoscale

“…Beyond topographical capability, AFM sensitivity to interatomic forces down to pN range [13] provides an easily configurable and extremely powerful test bench for fundamental studies in bionanotechnology [14]. For example, modified probes such as magnetic [15][16][17][18], conductive [19][20][21] and bio-functionalized tips [22][23][24][25] are widely used for local functional detection of an endless number of properties at nanoscale [26,27]. Most of the innovative applications of AFM rely on tip customization.…”

Characterization of Magnetic Nanoparticles Using Magnetic Force Microscopy

“…[2] . Using external magnetic fi elds and magnetic atomic force microscope tips, it is possible to characterize the dipolar nature of magnetic nanoparticles in ambient air.…”