Biocompatible Fe-Si Nanoparticles with Adjustable Self-Regulation of Temperature for Medical Applications.

Because of the noninvasive, locally selective potential of thermal energy, considerable effort has been focused on the use of an external, alternating magnetic field for conversion of magnetic work to heat with iron oxide nanoparticles. However, proper regulation of thermal energy remains a challenge because of the lack of feedback from the local temperature change to the external power supply. Here, we show development of smart magnetic nanoparticles composed of Fe and Si with intrinsically tunable heat generation capability. They were engineered to possess an adjustable magnetic transition temperature through tuning the exchange between Fe atoms by incorporation of silicon atoms. They show relatively high magnetic moment. Moreover, their biocompatibility was established in several cell lines. The nanoparticles were also combined with a thermosensitive polymer, which had the capability to release of molecules with a magnetic stimulus, thereby providing a platform for locally controlled, drug release.

Surface modification and bioconjugation of FeCo magnetic nanoparticles with proteins.

Magnetic Fe70Co30 nanoparticles with a cubic shape and a mean size of 15±1.5 nm were fabricated using a magnetron-sputtering-based gas phase condensation deposition method. The particles had a high saturation magnetization of 220 emu/g, which is much higher than that of commercially available iron oxide nanoparticles. The FeCo nanoparticles were modified by 3-aminopropyltriethoxy silane and subsequently activated by glutaraldehyde, leading to successful attachment of aldehyde groups onto nanoparticle surfaces. Three proteins, namely streptavidin, PAPP-A antibody and Nectin-4 antibody, were immobilized on glutaraldehyde activated FeCo nanoparticles, and their loading levels were quantitatively evaluated. Our results show that loading capabilities are 95 µg of streptavidin, 128 µg of PAPP-A, and 125 µg of Nectin-4 antibody per milligram of FeCo nanoparticles, and that the three immobilized proteins retain their binding bioactivity. The protein-FeCo conjugates may find valuable applications involving magnetic separation and purification of proteins and cells, and the magnetic detection of biomolecules.

High-magnetic-moment nanoparticles for biomedicine.

Magnetic nanoparticles play an important role in biomedical applications, such as MR imaging, drug delivery and hyperthermia. Nanoparticles made of high-moment materials like Fe-Co and Fe have become active in the field due to superior performance. Protected by a biocompatible shell (Au/Ag/Si/C), high-moment nanoparticles can retain their magnetic property over a long time and disperse well. By using a physical gas condensation technique, such high-moment nanoparticles and core-shell structured nanoparticles can be made and used for biomedicine.