以硫化铋纳米粒子为核，四氧化三铁纳米粒子为壳，二氧化硅介孔夹层为核壳之间的连接平台，形成集MRI和CT对比增强功能于一体的核壳结构纳米粒子。用连有叶酸和聚乙二醇的羧端基聚酰胺胺树枝状高分子对核壳结构纳米粒子进行表面修饰，以提高纳米粒子的分散稳定性、亲水性、靶向性和生物相容性。四氧化三铁纳米粒子在二氧化硅介孔层表面所具有的磁性协同效应和树枝状修饰层创造的亲水环境将赋予核壳结构纳米粒子强的MRI对比增强功能，硫化铋纳米粒子的高X-射线吸收系数将使纳米粒子具有强的CT对比增强功能。重点研究核-壳之间相互作用和CT、MRI两种对比增强信号的匹配性及相互影响规律；二氧化硅介孔层表面四氧化三铁纳米粒子磁性协同效应的影响规律及调控方法；树枝状高分子的修饰对分散稳定性、靶向性和生物相容性的影响等。MRI和CT对比剂在同一载体上的有效集成，将使MRI和CT联合成像分析更加有效。

Mutifunctional core-shell nanoparticles for MRI and CT contrast enhancement are prepared using bismuth sulfide nanoparticles as core, iron oxide nanoparticles as shell and mesoporous silica as the sandwiched layer. In order to improve their dispersion stability,hydrophilic,biocompatibility and targeting functionality, the surface of core-shell nanoparticles is modified by folic acid-poly(ethylene glycol)-functionalized carboxy-terminal polyamidoamine dendrimers.The high magnetic synergy of nanosized iron oxide attached on the silica mesoporous layer and the hydrophilic environment created by the dendrimer layer are anticipated to provide enhanced MRI properties, the strong X-ray absorption of bismuth sulfide nanoparticles is anticipated to provide improved CT properties. This project is mainly focused on core-shell interactions and the matching rules of CT and MRI contrast signal, the magnetic synergy of iron oxide nanoparticles attached on silica mesoporous layer, and the effect of functionalized polyamidoamine dendrimers on the dispersion stability, targeting and biocompatibility of core-shell nanoparticles.The intergratin of the CT and MRI contrast functions in the same vector will make MRT/CT imaging more available and effective.