Magnetic force microscopy

Abstract

Magnetic force microscopy (MFM) is an atomic force microscopy (AFM) based technique in which an AFM tip with a magnetic coating is used to probe local magnetic fields with the typical AFM spatial resolution, thus allowing one to acquire images reflecting the local magnetic properties of the samples at the nanoscale. Being a well established tool for the characterization of magnetic recording media, superconductors and magnetic nanomaterials, MFM is finding constantly increasing application in the study of magnetic properties of materials and systems of biological and biomedical interest. After reviewing these latter applications, three case studies are presented in which MFM is used to characterize: (i) magnetoferritin synthesized using apoferritin as molecular reactor; (ii) magnetic nanoparticles loaded niosomes to be used as nanocarriers for drug delivery; (iii) leukemic cells labeled using folic acid-coated core-shell superparamagnetic nanoparticles in order to exploit the presence of folate receptors on the cell membrane surface. In these examples, MFM data are quantitatively analyzed evidencing the limits of the simple analytical models currently used. Provided that suitable models are used to simulate the MFM response, MFM can be used to evaluate the magnetic momentum of the core of magnetoferritin, the iron entrapment efficiency in single vesicles, or the uptake of magnetic nanoparticles into cells.

Understanding electrostatic and magnetic forces in magnetic force microscopy: towards single superparamagnetic nanoparticle resolution

“…Magnetic force microscopy (MFM) proved to be a promising technique to successfully image clusters of small superparamagnetic nanoparticles without labelling and provides all the information described above in a single pass [7][8][9][10][11]. Recent investigations demonstrate the capability of MFM for biological systems e. g. to evaluate the iron distribution in biological tissues [12] and to study the cellular uptake of magnetic nanoparticles [13]. Nevertheless the interaction of the probe with nanoparticles is not yet fully understood.…”

Microscopic Techniques for the Analysis of Micro and Nanostructures of Biopolymers and Their Derivatives

“…In general, for successful MFM imaging, the sample is first scanned in the close range where the Van der Waals forces are dominant to acquire a topographical image and then the tip is lifted to a region where the magnetic forces are dominant and scanned for MFM image. This technique is advantageous as it minimizes the effects caused by non-magnetic forces and ensures only the record of magnetic forces [226,227]. The use of MFM in biopolymer systems is marginally explored and is limited to the analysis of magnetic biocomposites [83,[228][229][230][231].…”

Magnetic Force Microscopy of in a Polymer Matrix Embedded Single Magnetic Nanoparticles

“…MFM study of the surface of SPION nanocomposites showed that the distribution of SPIONs in a matrix can create domains in the nanocomposite . The high potential of MFM for biological and medical applications has been shown, for example, by visualization the iron core of ferritin as well as by studying the cellular uptake of SPIONs . Wang et al mapped the uptake of SPIONs into tumor cells and determined the intracellular iron content and spatial distribution of the intracellular iron .…”

“…Wang et al mapped the uptake of SPIONs into tumor cells and determined the intracellular iron content and spatial distribution of the intracellular iron . Passeri et al investigated the use of superparamagnetic core shell nanoparticles for cell labeling in vitro . Both Zhang et al and Passeri et al emphasize that the quantification from MFM images of depth information under the cell membrane is still challenging and further investigations and simulations are necessary.…”

“…Passeri et al investigated the use of superparamagnetic core shell nanoparticles for cell labeling in vitro . Both Zhang et al and Passeri et al emphasize that the quantification from MFM images of depth information under the cell membrane is still challenging and further investigations and simulations are necessary. In our study, we aim at a quantification of the MFM signal in order to determine the size of the nanoparticles embedded in a polymer matrix.…”