Magnetic nanoparticles: preparation, physical properties, and applications in biomedicine

Abstract

Finally, we have addressed some relevant findings on the importance of having well-defined synthetic strategies developed for the generation of MNPs, with a focus on particle formation mechanism and recent modifications made on the preparation of monodisperse samples of relatively large quantities not only with similar physical features, but also with similar crystallochemical characteristics. Then, different methodologies for the functionalization of the prepared MNPs together with the characterization techniques are explained. Theorical views on the magnetism of nanoparticles are considered.

Figure 1

Schematic illustration of the coercivity-size relations of small particles.

Figure 2

Magnetization behavior of ferromagnetic and superparamagnetic NPs under an external magnetic field. (a) Under an external magnetic field, domains of a ferromagnetic NP align with the applied field. The magnetic moment of single domain superparamagnetic NPs aligns with the applied field. In the absence of an external field, ferromagnetic NPs will maintain a net magnetization, whereas superparamagnetic NPs will exhibit no net magnetization due to rapid reversal of the magnetic moment. (b) Relationship between NP size and the magnetic domain structures. Ds and Dc are the 'superparamagnetism' and 'critical' size thresholds.

Figure 3

Schematic representation of the magnetically driven transport of drugs to a specific region. A catheter is inserted into an arterial feed to the tumor, and a magnetic stand is positioned over the targeted site.