超顺磁性石墨烯-Fe3O4复合纳米粒子对极低场磁共振弛豫时间的影响研究

项目名称： 超顺磁性石墨烯-Fe3O4复合纳米粒子对极低场磁共振弛豫时间的影响研究

项目编号： No.11204339

项目类型： 青年科学基金项目

立项/批准年度： 2013

项目学科： 物理学I

项目作者： 董慧

作者单位： 中国科学院上海微系统与信息技术研究所

项目金额： 30万元

中文摘要： 磁共振成像（MRI）技术已成为临床医学诊断不可或缺的手段之一。利用以超顺磁性Fe3O4纳米粒子（SPIO）为代表的MRI造影剂可显著提高图像对比度，但其对水分子弛豫行为的影响效果由磁场强度决定。石墨烯-Fe3O4复合纳米粒子作为新型MRI造影剂，具有优良的化学、磁稳定性和生物相容性。目前对该种纳米粒子的研究仅限于特斯拉（T）量级的强场下。基于超导量子干涉器件（SQUID）检测的极低场MRI工作于μT量级场强下，具有装置简单、价格低廉、可与脑磁图仪融合成像等优点，已成为国际SQUID应用研究热点。本项目拟利用极低场MRI系统研究石墨烯-Fe3O4复合纳米粒子在μT量级场强下对水分子弛豫行为的影响：拟通过控制工艺参数制备粒径可控的复合纳米粒子；拟研究极低场系统预极化场关断特性以提高测量信噪比；拟根据不同粒径、不同浓度复合纳米粒子分散液的弛豫时间，借助理论模型理解其与水分子在极低场下的相互作用。

中文关键词： 磁共振成像；极低场；石墨烯；Fe3O4纳米粒子；弛豫

英文摘要： Magnetic Resonance Imaging (MRI) is an essential technology in clinic diagnosis. MRI contrast agents, such as superparamagnetic iron oxide (SPIO) nanoparticles, may significantly increase the MRI image contrast. The influence of contrast agents on the relaxation behavior of proton in water is determined by the magnetic field strength. Graphene?Fe3O4 composite nanoparticles regarded as a new kind of contrast agent own the advantages of magnetic and chemical stability as well as biocompatibility. The current studies on graphene?Fe3O4 nanoparticles are all carried out at high fields on the order of tesla. The superconducting quantum interference device (SQUID)-based ultra-low field (ULF) MRI system works at the range of μT. The ULF MRI study becomes one of the hot topics in SQUID applications, due to its simple setup, cheap price and the possibility of hybrid imaging with magnetoencephalography (MEG). This project will focus on the influence of graphene?Fe3O4 nanoparticles on the relaxation of neighboring protons utilizing homemade ULF MRI system at microtesla range. The size-controlled composite nanoparticles will be prepared by adjusting the parameters. Then the pre-polarization field coil will be optimized in order to enhance the signal to noise ratio. Finally, in the light of theoretical model, the interactions

英文关键词： MRI；ultra-low field；graphene；Fe3O4 nanoparticles；relaxation