Interplay between Longitudinal and Transverse Contrasts in Fe3O4 Nanoplates with (111) Exposed Surfaces

详细信息    查看全文

• 作者：Zijian Zhou ; Zhenghuan Zhao ; Hui Zhang ; Zhenyu Wang ; Xiaoyuan Chen ; Ruifang Wang ; Zhong Chen ; Jinhao Gao
• 刊名：ACS Nano
• 出版年：2014
• 出版时间：August 26, 2014
• 年：2014
• 卷：8
• 期：8
• 页码：7976-7985
• 全文大小：644K
• ISSN：1936-086X

文摘

Iron oxide has been developed as either T₁ or T₂ magnetic resonance imaging (MRI) contrast agents by controlling the size and composition; however, the underlying mechanism of T₁ and T₂ contrasts in one iron oxide entity is still not well understood. Herein, we report that freestanding superparamagnetic magnetite nanoplates with (111) exposed facets have significant but interactional T₁ and T₂ contrast effects. We demonstrate that the main contribution of the T₁ contrast of magnetic nanoplates is the chemical exchange on the iron-rich Fe₃O₄(111) surfaces, whereas the T₂ relaxation is dominated by the intrinsic superparamagnetism of the nanoplates with an enhanced perturbation effect. We are able to regulate the balance of T₁ and T₂ contrasts by controlling structure and surface features, including morphology, exposed facets, and surface coating. This study provides an insightful understanding on the T₁ and T₂ contrast mechanisms, which is urgently needed to allow more sophisticated design of high-performance MRI contrast agents.

Keywords:

T₁ and T₂ contrasts; magnetite nanoplates; Fe₃O₄(111); morphology