Synthesis of Highly Magnetic, Air-Stable Iron–Iron Carbide Nanocrystalline Particles by Using Power Ultrasound A. Gedanken is grateful for the support of the German Ministry of Science through the Deutsche-Israeli DIP program. I. Felner and A. Gedanken thank also the Israeli Ministery of Science, Culture and Sport for an infrastructure grant. S. I. Nikitenko thanks the Bar-Ilan Research Authority for his fellowship. The authors also thank Dr. Shifra Hochberg for editorial assistance.

Abstract

A coating of iron carbide and carbon confers air‐stability on the nanocrystalline iron particles that were prepared by sonolysis of [Fe(CO)5] in diphenylmethane followed by annealing of the as‐prepared material. The saturation magnetization of this material (222 emu g−1, see picture) is almost as high as that of bulk bcc iron.

Sonochemistry and Other Novel Methods Developed for the Synthesis of Nanoparticles

“…Nikitenko has succeeded recently in preparing iron nanoparticles that are airstable [70]. Iron is easily oxidized in ambient conditions, but when it comes to iron nanoparticles they are pyrophoric and burn spontaneously in air.…”

“…Another carbide that has already been mentioned is that of Pd [65], which was prepared by Maeda's group. Iron carbide was a byproduct that served as protective layer in Nikitenko's work on air-stable iron nanoparticles [70].…”

Multifunctional biocompatible coatings on magnetic nanoparticles

“…Carbon layers protect the surface of MNPs from the action of chemical factors including oxidation. 18,359 Carbon coatings are formed by various methods, e.g., arc discharge, pyrolysis, chemical vapour phase deposition, etc. Fabrication of carbon coatings on iron, cobalt and nickel MNPs using electric arc between carbon electrodes was reported.…”

Iron-Loaded Magnetic Nanocapsules for pH-Triggered Drug Release and MRI Imaging

“…Recently, iron nanoparticles or iron nanoparticles with iron oxide shells have also gained attention as MRI contrast agents due to their higher magnetization and stronger shortening effect on T 2 relaxation time than IONPs. 16−19 However, the T 1 weighed MRI relaxivity of these iron nanoparticles ( r 1 = 1.2 s –1 mM –1 ) is not as good as FDA-approved T 1 weighted contrast agents such as Gd-DTPA ( r 1 = 6.2 s –1 mM –1 measured at 1.5 T). 17 Hence, a nanosystem combining the advantages of both stable iron nanoparticles with high saturation magnetization and biocompatible polymeric layer for pH triggered drug release is expected to expedite the development of multifunctional delivery systems.…”