多模态显影栓塞微球制备及体外显影实验

The preparation of multimodal imaging embolization microspheres and its visualization experiment in vitro

目的开发一种具备X线/CT/MR下多模态显影能力的明胶栓塞微球。方法采用乳化交联法制备单一携载固态纳米Fe_3O_4颗粒的明胶栓塞微球,光学显微镜观察微球形态、粒径、分散度;热重分析法检测微球内Fe_3O_4纳米颗粒载药量;X线、CT、MR检测评估多模态显影能力;利用兔心血及人血管内皮细胞行微球溶血试验及体外细胞毒性试验;观察微球弹性、溶胀特点及消毒方法。结果最优化微球合成条件为Fe_3O_4与明胶质量比为2∶1。该微球外观圆整、分散性好、成球率高(最高77.0%)、载药率高(最高73.27%)、粒径适中为(199.78±142.90)μm,具备X线/CT/MR下多模态显影能力,最优化微球CT值最高可达(1 028.0±69.5)Hu(浓度25 mg/ml),MR T_2值下降约50%(浓度4 mg/ml)。溶血试验及细胞毒性试验溶血率及吸光值与对照组相比,差异无统计学意义(P>0.05)。微球在酸性溶液中表现出溶胀特性,在无水乙醇中无溶胀现象。结论以固态Fe_3O_4纳米颗粒为显影材料,明胶为聚合物材料,采用乳化交联法可成功制备载药量高、形态规则、表面光滑、不易聚集、X线/CT/MR下多模态显影能力更强、生物安全性高、消毒方便的栓塞微球。

Objective To develop a kind of gelatin microspheres which is capable of being visualized on radiography, CT and MR examinations. Methods Emulsion chemical cross-linking method was used to prepare gelatin microspheres that carried only solid Fe304 nanoparticles. Optical microscope was adopted to observe the morphology, particle diameter and the dispersity of the gelatin microspheres. Using thermogravimetric analysis method, the loading rate of Fe3O4 nanoparticles encapsulated in the gelatin microspheres was calculated. The multimodal visualization ability of the gelatin microspheres was evaluated by radiography, CT and MR examinations. The blood in rabbit heart and human vascular endothelial cells were used to make microsphere hemolysis test and in vitro cytotoxicity test. The elastic characteristics and the swelling characteristics of the gelatin microspheres were determined, and the sterile technique was tested. Results The optimal synthesis condition of microspheres was to use 2 ： 1 of Fe3O4-to-gelatin quality ratio, under this situation, the microspheres showed a roundness appearance with satisfactory dispersion, the sphemlization rate was high （up to 77%）, the drug loading rate was very high （up to 73.27%）, the particle diameter was moderate （199.78±142.90μm）, and the microspheres had muhimodal visualization ability for radiography, CT and MR examinations. The optimization CT value of microspheres could be up to （1 028.0±69.5） Hu （when concentration=25 mg/ml）. Hemolysis test and in vitro cytotoxicity test showed that no statistically significant differences in the hemolysis rate and absorption value existed between the study group and the control group （P〉0.05）. In acid solution, the microspheres exhibited swelling characteristics, while in ethanol the microspheres showed no swelling phenomenon. Conclusion Using solid Fe3O4 nanoparticles as visualization material as well as gelatin as polymer materials, a special gelatin microspheres can be prepared with emulsion chemical cross-linking method. This kind of microspheres carries the following features： high drug loading, regular in shape, smooth surface, not easy to agglomerate, stronger multimodal visualization ability （radiography, CT and MR）, high biological safety and convenient disinfection.