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

An ultra-fast method to synthesize mesoporous magnetite (Fe(3)O(4)) 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 5 min was needed in the synthesis. The diameter of the nanoclusters could be controlled effectively between 75 nm and 115 nm by increasing the amount of iron (III) acetylacetonate. Brunauer-Emmett-Teller (BET) results reveal a mesoporous structure and a large surface area of 72.3 m(2) g(-1). Cytotoxicity test performed in HepG2 cell line indicated that the as-prepared nanoclusters were non-cytotoxic. The nanoclusters exhibited an enhanced T(2) relaxivity value of 417.4±29.9 s(-1) mM(-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.