中文摘要：

Superparamagnetic 氧化铁(SPIO ) nanoparticles 是为在织物的磁性的回声成像的改进的有效对比代理人，细胞或平的分子的层次。高质量的 SPIO nanoparticles 能在器官的阶段被综合，但是需要在任何生物医学的应用前被变成水。在这研究， amphiphilic (ε-caprolactone ) poly， grafted 葡聚糖(Dex-g-PCL ) 在水的阶段为粒子封装和稳定被用作搬运人。多重 SPIO nanoparticles 在从氯仿的阶段转移期间和 Dex-g-PCL 的帮助是自我装配的到水，并且 Dex-g-PCL/SPIO nanocomposites 的直径是 64 ± 22 ) 通过散布测量的动态光的 nm。这些 nanocomposites 是超级的在有 88 emu/g Fe 的浸透的磁化的 300 K 顺磁。在 1.5 T 的磁场， Dex-g-PCL/SPIO nanocomposites 有 363 Fe mL · m ol ⁻¹ · s⁻¹ 的 T2 relaxivity。这唯一的 nanocomposite 在静脉内的管理以后在 5 min 与 −60% 的信号紧张变化带了重要老鼠肝对比。然而，在肝的 Dex-g-PCL/SPIO nanocomposites 的举起网状内皮组织的房间(Kupffer 房间) 是由组织学研究验证了立即没在更短的时间点(〈4 h ) 发生，并且染色的更多的铁将位于 Kupffer 房间，是明显的在对比代理人管理以后的 24 h。在 24 h 和 10 d 以后，信号紧张(SI ) 逐渐地恢复了，并且 SI 变化分别地是 −44% 和 −31% 。从我们的观察，为 enhanced-MRI 的时间窗户至少 12 天能持续并且完全在 16 天以后恢复。这个新奇敏感 MRI 对比代理人可以在发现象早肿瘤诊断那样的小肝损害发现潜在的应用。

英文摘要：

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.