Mesoporous Magnetite Research Articles

Ultra-fast method to synthesize mesoporous magnetite nanoclusters as highly sensitive magnetic resonance probe

An ultra-fast method to synthesize mesoporous magnetite (Fe3O4) nanoclusters is reported. These mesoporous magnetite can be used as a highly sensitive magnetic resonance imaging (MRI) probe. The nanoclusters were synthesized by reducing iron (III) acetylacetonate with hydrazine in ethylene glycol under microwave irradiation and only 5min was needed in the synthesis. The diameter of the nanoclusters could be controlled effectively between 75nm and 115nm by increasing the amount of iron (III) acetylacetonate. Brunauer–Emmett–Teller (BET) results reveal a mesoporous structure and a large surface area of 72.3m2g−1. Cytotoxicity test performed in HepG2 cell line indicated that the as-prepared nanoclusters were non-cytotoxic. The nanoclusters exhibited an enhanced T2 relaxivity value of 417.4±29.9s−1mM−1. In vitro and in vivo MRI confirmed the high sensitivity of the magnetite nanoclusters as MRI probe. The biodistribution of the nanoclusters in rat liver and spleen after intravenous injection was also investigated.

Assembly of magnetite nanocrystals into spherical mesoporous aggregates with a 3-D wormhole-like pore structure

Spherical mesoporous magnetite (Fe3O4) aggregates with a wormhole-like pore structure were successfully synthesized for the first time using a single iron precursor (iron(III) ethoxide) and an amphiphilic poly(ethylene oxide)-block-poly(propylene oxide)-block-poly(ethylene oxide) triblock copolymer (PEO100–PPO65–PEO100) as a soft template. In this synthesis, the interaction between the iron precursor and the triblock copolymer self-assemblies in ethanol leads to the assembly of magnetite nanocrystals into spherical mesoporous aggregates. These aggregates were characterized using Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, field-emission scanning electron microscopy, standard and high-resolution transmission electron microscopy, 57Fe Mössbauer spectroscopy, and X-ray diffraction, confirming the formation of pure-phase Fe3O4 particles with monodisperse morphology (about 130 nm in diameter), three-dimensional wormhole-like mesopores, and highly crystalline spinel structure. In addition, a formation mechanism for this material in the present system is proposed, based on the analysis of results. The mesoporous magnetite has a high specific surface area of 165.6 m2 g−1, and relatively large pores with a mean size of 5.2 nm. The magnetic susceptibility data demonstrate that this material exhibits superparamagnetic behavior.

Preparation, structure, and magnetic properties of mesoporous magnetite hollow spheres

Preparation of mesoporous Fe 3O 4 (magnetite) hollow spheres has been reported using hydrothermal synthesis and calcinations. The carboxyl-functionalized PS spheres were used as the templates coated by Fe 3O 4 particles and ethylene glycol (EG) as an organic structure directing agent. PS and EG were removed by calcinations method. The surface area after calcination at 500 °C is found to be 74 m 2 g −1. The hollow spheres exhibited the weak ferromagnetism.