Tunable High Aspect Ratio Iron Oxide Nanorods for Enhanced Hyperthermia

详细信息    查看全文

• 作者：Raja Das ; Javier Alonso ; Zohreh Nemati Porshokouh ; Vijaysankar Kalappattil ; David Torres ; Manh-Huong Phan ; Eneko Garaio ; José Ángel García ; Jose Luis Sanchez Llamazares ; Hariharan Srikanth
• 刊名：Journal of Physical Chemistry C
• 出版年：2016
• 出版时间：May 12, 2016
• 年：2016
• 卷：120
• 期：18
• 页码：10086-10093
• 全文大小：578K
• 年卷期：0
• ISSN：1932-7455

文摘

Despite magnetic hyperthermia being considered one of the most promising techniques for cancer treatment, until now spherical magnetite (Fe₃O₄) or maghemite (γ-Fe₂O₃) nanoparticles, which are the most commonly employed and only FDA approved materials, yield the limited heating capacity. Therefore, there is an increasing need for new strategies to improve the heating efficiency or the specific absorption rate (SAR) of these nanosystems. Recently, a large improvement in SAR has been reported for nanocubes of Fe₃O₄ relative to their spherical counterpart, as a result of their enhanced surface anisotropy and chainlike particle formation. Considering the proven advantages of high aspect ratio one-dimensional (1D) Fe₃O₄ nanostructures over their spherical and cubic counterparts, such as larger surface area, multisegmented capabilities, enhanced blood circulation time, and prolonged retention in tumors, we propose a novel approach that utilizes this 1D nanostructure for enhanced hyperthermia. Here, we demonstrate that the SAR of iron oxide nanostructures can be enhanced and tuned by altering their aspect ratio. Calorimetric and ac magnetometry experiments performed for the first time on highly crystalline Fe₃O₄ nanorods consistently show large SAR values (862 W/g for an ac field of 800 Oe), which are superior to spherical and cubic nanoparticles of similar volume (∼140 and ∼314 W/g, respectively). Increasing the aspect ratio of the nanorods from 6 to 11 improves the SAR by 1.5 times. The nanorods are rapidly aligned by the applied ac field, which appreciably increases the SAR values. A detailed analysis of the effect of the alignment of the nanorods in agar indicates an appreciable SAR increase up to 30% when the nanorods are parallel to the field. These findings pave a new pathway for the design of novel high-aspect ratio magnetic nanostructures for advanced hyperthermia.