FeCo/graphitic-shell nanocrystals as advanced magnetic-resonance-imaging and near-infrared agents
FeCo/graphitic-shell nanocrystals as advanced magnetic-resonance-imaging and near-infrared agents
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DOI：
10.1038/nmat1775
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发表时间：
2006-12-01
期刊：
影响因子：
41.2
通讯作者：
Dai, Hongjie
中科院分区：
文献类型：
--
作者：
Seo, Won Seok;Lee, Jin Hyung;Dai, Hongjie
具有先进磁性或光学性质的纳米晶体已被积极地用于潜在的生物应用，包括集成成像，诊断和治疗，。在众多的磁性纳米晶中，FeCo具有上级磁性能，但由于易氧化和潜在的毒性等问题，目前还有待于进一步研究。以前，已经获得了具有多层石墨碳、热解碳或惰性金属的FeCo纳米晶体，但不是生物应用所需的单壳、离散、化学官能化和水溶性形式。在这里，我们提出了一种可扩展的化学气相沉积方法来合成FeCo/单石墨壳纳米晶体，这些纳米晶体在水溶液中可溶且稳定。我们探索这些核-壳材料的多功能性，通过表征FeCo核的磁性和单层石墨壳的近红外光吸收。该纳米晶在近红外区具有超高的饱和磁化强度、弛豫系数r1和r2以及高的光吸收率。间充质干细胞能够内化这些纳米颗粒，在磁共振成像（MRI）中显示出高的负对比度增强。在体实验实现了兔血管MRI的长期正对比增强。这些结果指出了使用这些纳米晶体用于集成诊断和治疗（光热消融）应用的潜力。
Nanocrystals with advanced magnetic or optical properties have been actively pursued for potential biological applications, including integrated imaging, diagnosis and therapy,,,,,,,,. Among various magnetic nanocrystals,,,,,, FeCo has superior magnetic properties, but it has yet to be explored owing to the problems of easy oxidation and potential toxicity,,. Previously, FeCo nanocrystals with multilayered graphitic carbon, pyrolytic carbon or inert metals have been obtained,,, but not in the single-shelled, discrete, chemically functionalized and water-soluble forms desired for biological applications. Here, we present a scalable chemical vapour deposition method to synthesize FeCo/single-graphitic-shell nanocrystals that are soluble and stable in water solutions. We explore the multiple functionalities of these core–shell materials by characterizing the magnetic properties of the FeCo core and near-infrared optical absorbance of the single-layered graphitic shell. The nanocrystals exhibit ultra-high saturation magnetization,r1andr2relaxivities and high optical absorbance in the near-infrared region. Mesenchymal stem cells are able to internalize these nanoparticles, showing high negative-contrast enhancement in magnetic-resonance imaging (MRI). Preliminaryin vivoexperiments achieve long-lasting positive-contrast enhancement for vascular MRI in rabbits. These results point to the potential of using these nanocrystals for integrated diagnosis and therapeutic (photothermal-ablation) applications.