【作者】 杜玉卿；

【导师】 刘祖黎；

【作者基本信息】 华中科技大学 ， 凝聚态物理， 2004， 硕士

【摘要】 近年来,由于其特殊性能,纳米磁性材料越来越多地应用到生物技术和生物医学工程方面,如磁分离、靶向药物和磁共振对比剂等等。目前对于磁共振检测来说,30%都需要磁共振对比剂来提高信号的对比度,因此制备研究新型的磁共振对比剂具有很重要的科学意义和医疗诊断价值。我们在共沉淀法的基础上制备出了一种超小型超顺磁性氧化铁磁共振对比剂—纳米氧化铁粒子为核心,外面包裹高聚物。作为超小型超顺磁性磁共振对比剂,样品必须稳定性及分散性好,粒子粒径在10纳米以下。如何使纳米粒子有良好的分散性一直是纳米材料领域的热点问题之一,我们最终选用具有生物相容性、可降解、亲水性长链高聚物葡聚糖作为稳定剂包覆氧化铁纳米粒子,得到了分散性良好的可作为磁共振对比剂的稳定的磁流体。在实验过程中发现,葡聚糖加入量的多少决定样品是否形成稳定的胶体。超顺磁性是超小型超顺磁性磁共振对比剂的另一个必要条件。我们对同一样品的磁性能进行了两次测量,中间时间间隔为6个月。两次测量结果显示,两次测量均显示了超顺磁性,且饱和磁化强度相差不大,原因是葡聚糖包覆材料对氧化铁的磁稳定性起了很大作用。此外,我们还通过粘度仪、热分析和红外光谱对样品粘度、热稳定性和表面包覆情况进行了研究。最后,为了验证我们所作样品作为磁共振对比剂的效果,我们进行了动物肝脏的磁共振成像实验,结果表明,我们所制备的样品对成像信号有明显的增强效果,是一种很有前途的磁共振对比剂-超小型超顺磁性氧化铁磁共振对比剂。更多还原

【Abstract】 In recent years,because of its special properties, nano-material has been wildly applied to various aspects in biotechnology and biomedical engineering, such as magnetic separation, target drug and magnetic resonance imaging (MRI) contrast agent, et al. Currently, about one-third of MRI scans are in need of administration of a contrast agent to improve the contrast of signals. Therefore, it is of great scientific significance and diagnostic value to synthesize and study new types of MRI contrast agent.Based on the method of co-precipitation, we synthesized a kind of ultrasmall superparamagnetic iron oxide (USPIO) MRI contrast agent—nanosized iron-oxide particles surrounded by polymer. To be as USPIO MRI contrast agent, the sample must be stable, well dispersed and the diameter of the particles must be no more than 10 nm. How to get well-dispersed nanopartilces has always been one of the intense researches in the area of nanomaterial. We at last chose the polymer dextran which is biocompatible, biodegradable and hydrophilic as the coating material and get magnetic fluid in well dispersed state which can be used as MRI contrast agent. It is found that the quantity of the dextran is a major factor for the formation of stable colloid.Superparamagnetism is another indispensable property to USPIO contrast agent. We conducted magnetic measurements in two different times to the same sample. The period between the two measurements is about six months. The two results manifested both measurements have superparamagnetism and there is not much difference in the saturation magnetization. It is the coating material dextran that improved the magnetic stability. Moreover, we also studied the properties of viscidity,thermostability and surface.At last, to test the effect of our sample to be as MRI contrast agent, we conducted MRI experiments in animal liver. The results indicate that the sample we synthesized can greatly improve the signal contrast and can be a good candidate for MRI contrast agent-USPIO MRI contrast agent.更多还原