目的 制备载超顺磁氧化铁(SPIO)纳米粒和DiI荧光高分子微球(DiI-SPIO-PLGA),探讨其作为MRI对比剂体外巨噬细胞成像的效果和作为荧光示踪剂体外示踪巨噬细胞的可行性.方法 采用双乳化法制备DiI-SPIO-PLGA微球,并检测其理化性质.培养小鼠RAW264.7巨噬细胞,与DiI-SPIO-PLGA微球共孵育12 h后行普鲁士蓝染色和荧光显微镜观察,将吞噬了微球的细胞和空白细胞分别重悬于0.5 ml 1％琼脂糖Eppendof管中,行MR扫描.结果 所得样品为外壳装载SPIO颗粒和DiI荧光的微球,粒径(868.00士68.73)nm.普鲁士蓝染色结果显示,几乎所有细胞内都有蓝染颗粒分布,部分区域聚集成堆；倒置荧光显微镜F可见细胞内有大量红色微球.MRI显示吞噬了DiI-SPIO-PLGA微球的实验组管内信号显著降低,管内信号值/背景信号值明显低于对照组(P＜0.05).结论 DiI-SPIO-PLGA微球能有效加强MR成像效果,荧光信号强烈,可同时作为MRI阴性对比剂和荧光示踪剂.%Objective To prepare superparamagnetic iron oxide (SPIO) and l,l'-dioctadecyl-3,3,3',3'-tetramethylindocar-bocyanine perchlorate loaded polymer microspheres (Dil-SPIO-PLGA), and to explore its potential application as a MRI contrast agent. Methods Dil-SPIO-PLGA microspheres were prepared using double emulsion method. Then the physical and chemical properties were observed. Dil-SPIO-PLGA microspheres were cultured with macrophages (RAW264. 7 cell line) in vitro for 12 h to observe the uptake by macrophages after Prussian blue staining and fluorescence microscopy. The uptake microspheres cells and the blank cells were resuspended in 0. 5 ml 1% agarose Eppendof tubes for MR scanning, respectively. Results The samples with the diameter of (868. 00±68. 73)nm consisted of SPIO particles and fluorescence Dil in the shell and water in the core. Prussian blue staining showed that almost all cells had stained blue particle distribution, part of the region gathered piles, and a large number of red microspheres were seen inside the cells by inverted fluorescence microscope. MRI showed that the signal in the tube of engulfed Dil-SPIO-PLGA microspheres cell group significantly reduced, the signal ratio of the tube to background was significantly lower than the control group (P<0. 05). Conclusion Dil-SPIO-PLGA microspheres can effectively enhance MRI with a strong fluorescence signal, therefore can be used as MRI contrast agents and fluorescent tracers at the same time.
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