Large-Scale Synthesis of Colloidal Fe3O4 Nanoparticles Exhibiting High Heating Efficiency in Magnetic Hyperthermia

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• 作者：Yury V. Kolen鈥檏o ; Manuel Ba帽obre-L贸pez ; Carlos Rodr铆guez-Abreu ; Enrique Carb贸-Argibay ; Alexandra Sailsman ; Yolanda Pi帽eiro-Redondo ; M. F谩tima Cerqueira ; Dmitri Y. Petrovykh ; Kirill Kovnir ; Oleg I. Lebedev ; Jos茅 Rivas
• 刊名：Journal of Physical Chemistry C
• 出版年：2014
• 出版时间：April 24, 2014
• 年：2014
• 卷：118
• 期：16
• 页码：8691-8701
• 全文大小：606K
• 年卷期：v.118,no.16(April 24, 2014)
• ISSN：1932-7455

文摘

Exceptional magnetic properties of magnetite, Fe₃O₄, nanoparticles make them one of the most intensively studied inorganic nanomaterials for biomedical applications. We report successful gram-scale syntheses, via hydrothermal route or controlled coprecipitation in an automated reactor, of colloidal Fe₃O₄ nanoparticles with sizes of 12.9 卤 5.9, 17.9 卤 4.4, and 19.8 卤 3.2 nm. To investigate structure鈥損roperty relationships as a function of the synthetic procedure, we used multiple techniques to characterize the structure, phase composition, and magnetic behavior of these nanoparticles. For the iron oxide cores of these nanoparticles, powder X-ray diffraction and electron microscopy both confirm single-phase Fe₃O₄ composition. In addition to the core composition, the magnetic performance of nanoparticles in the 13鈥?0 nm size range can be strongly influenced by the surface properties, which we analyzed by three complementary techniques. Raman scattering and X-ray photoelectron spectroscopy (XPS) measurements indicate overoxidation of nanoparticle surfaces, while transmission electron microscopy (TEM) shows no distinct core鈥搒hell structure. Considered together, Raman, XPS, and TEM observations suggest that our nanoparticles have a gradually varying nonstoichiometric Fe₃O_4+未 composition, which could be attributed to the formation of Fe₃O₄鈥撐?Fe₂O₃ solid solutions at their outermost surface. Detailed analyses by TEM reveal that the hydrothermally produced samples include single-domain nanocrystals coexisting with defective twinned and dimer nanoparticles, which form as a result of oriented-attachment crystal growth. All our nanoparticles exhibit superparamagnetic-like behavior with a characteristic blocking temperature above room temperature. We attribute the estimated saturation magnetization values up to 84.01 卤 0.25 emu/g at 300 K to the relatively large size of the nanoparticles (13鈥?0 nm) coupled with the syntheses under elevated temperature; alternative explanations, such as surface-mediated effects, are not supported by our spectroscopy or microscopy measurements. For these colloids, the heating efficiency in magnetic hyperthermia correlates with their saturation magnetization, making them appealing for therapeutic and other biomedical applications that rely on high-performance nanoparticle-mediated hyperthermia.