High-moment magnetic nanoparticles

In recent years, high-moment magnetic nanoparticles (MNPs) such as FeCo are attracting intense interest for biomedical applications. The synthesized FeCo MNPs have the specific saturation magnetization up to 226 emu/g that is more than three times higher than that of iron oxide MNPs (similar to 70-80 emu/g). Core-shell MNPs are also synthesized to enhance the functionality of high-moment MNPs. Shells like SiO2, Au, and Ag are used for these high-moment MNPs to improve biocompatibility. The sputtering-based gas-phase condensation approach to synthesize high-moment MNPs and core-shell nanostructures are reviewed. The applications of these high-moment MNPs such as magnetic hyperthermia, drug delivery, magnetic resonance imaging (MRI), and biosensing are summarized. The heating efficiency of magnetic hyperthermia and drug delivery could be significantly enhanced by using high-moment MNPs. MNPs with different crystallinity and shapes (such as cubic, spherical, triangular, and octahedral shapes) are also summarized due to their potential applications in MRI. High-moment MNPs could also provide more magnetic signals for giant magnetoresistance (GMR)-based biosensors, which are also reviewed. We believe that the high-moment MNPs are promising candidates for many bio-applications.