426514 Controlled Synthesis of Fe3O4 Single Crystal Spheres for Biomedical Application

Monday, November 9, 2015
Exhibit Hall 1 (Salt Palace Convention Center)
Yan Hao, school of materials science and engineering, tsinghua university, beijing, China

Spherical Fe3O4 particles with tunable diameters and structures have been successfully synthesized using a modified one-pot solvothermal method in an ethylene glycol/diethylene glycol (EG/DEG) binary system, with the assistance of dodecylamine (DDA). The obtained Fe3O4 particles varied from solid nanospheres about 15nm to hollow microspheres about 500nm via careful adjustment of the VEG/VDEG ratio. All the individual particles demonstrated a remarkable feature of single crystal no matter what the size and structure they were. The as-prepared Fe3O4 spheres exhibited superparamagnetic properties with relatively high saturation magnetization (~93emu/g) at room temperature, strong magnetocaloric effect (up to 68.5℃ in 3 min) and large BET surface area (~30m2/g). Based on serials of experiments, a reasonable formation mechanism of the Fe3O4 spheres were proposed, attributing to the cooperation of oriented aggregation, gas-bubble-assisted Ostwald ripening process and regulation of viscosity. Fe3O4 nanospheres around 50nm in diameter were tested to be nontoxic. The application of these nanospheres in MRI in vitro showed a high T2 relaxivity, their application in vivo demonstrated significant enhancement on the image contrast and concentrated aggregation of Fe3O4 nanospheres in tumor rather than other organs, which inferred that these nanospheres could be served as ideal candidates for MRI contrast agents.

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