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目的 制备内皮性白细胞粘附分子-1(ELAM-1)靶向性MR分子探针,分析其表征,并对其体内靶向性进行探讨.方法 制备:将羧基修饰过的超小型氧化铁颗粒(USPIO)与ELAM-1的配体唾液酸化酶X(sLeX)进行偶联,再以聚乙二醇(PEG)修饰,制备出靶向ELAM-1的MR分子探针USPIO-sLeX-PEG.表征:分别对USPIO和USPIO-sLeX-PEG进行激光动态光散射、热失重、红外光谱以及弛豫性能测试;靶向效果:分别测量两组荷瘤裸鼠瘤灶注药前后的T2值,比较USPIO及USPIO-sLeX-PEG在荷瘤裸鼠MR-T2 mapping上的成像效果,扫描完成后对其精细解剖,取组织病理切片行HE染色及免疫组织化学.结果 ELAM-1分子探针USPIO-sLeX-PEG主要表征:US-PIO-sLeX-PEG水动力尺寸为(51.82 ±5.2)nm,聚合物分散指数为(0.233±0.032);Zeta电位为(-40.17 ±0.55)mV.USPIO-sLeX-PEG分子探针的纵向率r1及横向弛豫率r2分别为6.1 mM-1·s-1、23.6 mM-1·s-1.靶向效果显示:非靶向性USPIO组与靶向性USPIO-PEG-sLeX组比较,后者的增强扫描T2值低于前者(P＜0.05),且后者强化率高于前者(P＜0.05),即USPIO-PEG-sLeX组荷瘤裸鼠在MR-T2 mapping上具有更好的成像效果.免疫组织化学结果示2组荷瘤裸鼠瘤灶ELAM-1均呈高表达.结论 合成的ELAM-1靶向性MR分子探针USPIO-sLeX-PEG表征良好,且对荷瘤裸鼠ELAM-1具有较好的靶向性.“,”Objective To synthesize ELAM-1 targeted MR molecular probe,and verify its targeting efficiency in vivo.Methods Synthesis:USPIO (ultra small iron oxide particles) modified with carboxyl was coupled to sLeX(Sialylase X),which is the ligand of ELAM-1 (endothelial leukocyte adhesion molecule-1),and then modified with PEG (polyethylene glycol) to prepare MR molecule probe USPIO-sLeX-PEG that targeting ELAM-1.Characterization:The laser dynamic light scattering,thermogravimetric analysis,infrared spectroscopy,and relaxation performance tests were performed on USPIO-sLeX-PEG and USPIO,respectively.Targeting effect:T2 values of the tumor were measured before and after injection.The imaging effect of USPIO and USPIO-sLeX-PEG for tumor-bearing nude mice on MR-T2 mapping were compared,after scanning,the tumor-bearing nude mice were subjected to fine anatomy,then histopathological sections were obtained for HE staining and immunohistochemistry.Results The main characterization of USPIO-sLeX-PEG (molecular probe of ELAM-1):The hydrodynamic size of USPIO-sLeX-PEG was (51.82 ± 5.2) nm,the polymer dispersion index was (0.233 ±0.032),and the zeta potential was (-40.17 ± 0.55) mv.The longitudinal rate r1 and lateral relaxation rate r2 of USPIO-sLeX-PEG molecular probes were 6.1 mM-1 · s-1 and 23.6 mM-1 · s-1,respectively.The targeting efficiency:Compared to non-targeted USPIO group,the target molecular probe USPIO-sLeX-PEG group showed lower T2 value and higher enhancement rate after injection.That is,the USPIO-PEG-LeX group has a better imaging effect on MR-T2 mapping.The results of immunohistochemistry showed that ELAM-1 was highly expressed in two groups of tumor-bearing nude mice.Conclusion The synthesized ELAM-1 Targeted MR Molecular Probes USPIO-sLeX-PEG was well characterized,and had a good targeting efficiency for ELAM-1 in tumor-bearing nude mice.