Amphiphilic dextran/magnetite nanocomposites as magnetic resonance imaging probes  

作　　者：WANG QiaoYing SU HongYing XIA ChunChao SUN JiaYu LIU Chen WANG ZhiYong GONG QiYong SONG Bin GAO FaBao AI Hua GU ZhongWei 

机构地区：[1]National Engineering Research Center for Biomaterials, Sichuan University, Chengdu 610064, China [2]Department of Radiology, West China Hospital, Sichuan University, Chengdu 610041, China

出　　处：《Chinese Science Bulletin》2009年第17期2925-2933,共9页

基　　金：Supported by the Program for New Century Excellent Talents in University (Grant No. NCET-06-0781);Distinguished Young Scholars Project of Sichuan Province (Grant No. 06ZQ026-007);National Natural Science Foundation of China (Grant Nos. 30570514, 50603015 & 50830107);National Basic Research Program of China (Grant No. 2005CB623903)

摘　　要：Superparamagnetic iron oxide (SPIO) nanoparticles are effective contrast agents for enhancement of magnetic resonance imaging at the tissue, cellular or even molecular levels. High quality SPIO nanoparticles can be synthesized in the organic phase but need to be transferred into water before any biomedical applications. In this study, amphiphilic poly(ε-caprolactone) grafted dextran (Dex-g-PCL) was used as carriers for particle encapsulation and stabilization in the aqueous phase. Multiple SPIO nanoparticles were self-assembled together with the help of Dex-g-PCL during phase transfer from chloroform to water, and diameters of Dex-g-PCL/SPIO nanocomposites were (64 ± 22) nm through dynamic light scattering measurement. These nanocomposites were superparamagnetic at 300 K with saturated magnetization of 88 emu/g Fe. In the magnetic field of 1.5 T, Dex-g-PCL/SPIO nanocomposites had a T2 relaxivity of 363 Fe mL·mol-1·s-1. This unique nanocomposite brought significant mouse liver contrast with signal intensity changes of -60% at 5 min after intravenous administration. However, uptake of Dex-g-PCL/SPIO nanocomposites in liver reticuloendothelial cells (Kupffer cells) did not immediately happen at shorter time points (<4 h) as verified by histology studies, and it was evident that more iron staining would be located in Kupffer cells 24 h after contrast agent administration. After 24 h and 10 d, the signal intensities (SI) gradually recovered, and SI changes were -44% and -31%, respectively. From our observation, the time window for enhanced-MRI could last at least 12 days and totally recovered after 16 days. This novel sensitive MRI contrast agent may find potential applications in discovering small liver lesions such as early tumor diagnosis.Superparamagnetic iron oxide （SPIO） nanoparticles are effective contrast agents for enhancement of magnetic resonance imaging at the tissue, cellular or even molecular levels. High quality SPIO nanoparticles can be synthesized in the organic phase but need to be transferred into water before any biomedical applications. In this study, amphiphilic poly（ε-caprolactone） grafted dextran （Dex-g-PCL） was used as carriers for particle encapsulation and stabilization in the aqueous phase. Multiple SPIO nanoparticles were self-assembled together with the help of Dex-g-PCL during phase transfer from chloroform to water, and diameters of Dex-g-PCL/SPIO nanocomposites were （64 ± 22） nm through dynamic light scattering measurement. These nanocomposites were superparamagnetic at 300 K with saturated magnetization of 88 emu/g Fe. In the magnetic field of 1.5 T, Dex-g-PCL/SPIO nanocomposites had a T2 relaxivity of 363 Fe mL·mol-1·s-1. This unique nanocomposite brought significant mouse liver contrast with signal intensity changes of -60% at 5 min after intravenous administration. However, uptake of Dex-g-PCL/SPIO nanocomposites in liver reticuloendothelial cells （Kupffer cells） did not immediately happen at shorter time points （〈4 h） as verified by histology studies, and it was evident that more iron staining would be located in Kupffer cells 24 h after contrast agent administration. After 24 h and 10 d, the signal intensities （SI） gradually recovered, and SI changes were -44% and -31%, respectively. From our observation, the time window for enhanced-MRI could last at least 12 days and totally recovered after 16 days. This novel sensitive MRI contrast agent may find potential applications in discovering small liver lesions such as early tumor diagnosis.

关 键 词：纳米复合材料 磁共振成像 磁铁矿 葡聚糖 探针 

分 类 号：TB332[一般工业技术—材料科学与工程] O482.531[理学—固体物理]