Syntheses of Fe-Ni Magnetic Nanoparticles and Their Applications on Biologic Labeling

In this study, we compared FeNi alloy magnetic nanoparticles (MNPs) prepared by either combustion or chemical precipitation methods. We found that the FeNi MNPs generated by combustion method have a rather high saturation magnetization Ms of～180 emu/g and a coercivity field Hc of near zero. However, the alloy nanoparticles are easily aggregated and are not well dispersive such that size distribution of the nanoparticle clusters is wide and clusters are rather big (around 50～700 nm). To prepare a better quality and well dispersed Fe-Ni MNPs, we also developed a thermal reflux chemical precipitation method to synthesize FeNi3 alloy MNPs. The precursor chemicals of Fe(acac)3 and Ni(acac)2 in a molecular ratio 1,2-hexadecandiol and tri-n-octylphosphine oxide (TOPO) were used as reducer and surfactant, respectively. The chemically precipitated FeNi3 MNPs are well dispersed and have well-controlled particle sizes around 10～20 nm with a very narrow size distribution (±1.2 nm). The highly monodispersive FeNi3 MNPs present good uniformity in particle shape and crystallinity on particle surfaces. The MNPs exhibit well soft magnetism with saturation magnetization of ～61 emu/g and Hc～0. The biomedically compatible FeNi MNPs which were coated with biocompatible polyethyleneimine (PEI) polymer were also synthesized. We demonstrated that the PEI coated FeNi MNPs can enter the mammalian cells in vitro and can be used as a magnetic resonance imagine (MRI) contrast agent. The results demonstrated that FeNi MNPs potentially could be applied in the biomedical field. The functionalized magnetic beads with biocompatible polymer coated on MNPs are also completed for biomedical applications.

Syntheses of Fe-Ni Magnetic Nanoparticles and Their Applications on Biologic Labeling

In this study, we compared FeNi alloy magnetic nanoparticles (MNPs) prepared by either combustion or chemical precipitation methods. We found that the FeNi MNPs generated by combustion method have a rather high saturation magnetization Ms of～180 emu/g and a coercivity field Hc of near zero. However, the alloy nanoparticles are easily aggregated and are not well dispersive such that size distribution of the nanoparticle clusters is wide and clusters are rather big (around 50～700 nm). To prepare a better quality and well dispersed Fe-Ni MNPs, we also developed a thermal reflux chemical precipitation method to synthesize FeNi3 alloy MNPs. The precursor chemicals of Fe(acac)3 and Ni(acac)2 in a molecular ratio 1,2-hexadecandiol and tri-n-octylphosphine oxide (TOPO) were used as reducer and surfactant, respectively. The chemically precipitated FeNi3 MNPs are well dispersed and have well-controlled particle sizes around 10～20 nm with a very narrow size distribution (±1.2 nm). The highly monodispersive FeNi3 MNPs present good uniformity in particle shape and crystallinity on particle surfaces. The MNPs exhibit well soft magnetism with saturation magnetization of ～61 emu/g and Hc～0. The biomedically compatible FeNi MNPs which were coated with biocompatible polyethyleneimine (PEI) polymer were also synthesized. We demonstrated that the PEI coated FeNi MNPs can enter the mammalian cells in vitro and can be used as a magnetic resonance imagine (MRI) contrast agent. The results demonstrated that FeNi MNPs potentially could be applied in the biomedical field. The functionalized magnetic beads with biocompatible polymer coated on MNPs are also completed for biomedical applications.