中文摘要：

目的制备基于胰腺癌生存素（Survivin）基因靶的MR分子探针,研究其对人胰腺癌细胞株BxPC-3的转染以及MRI的可行性。材料与方法将Survivin反义寡核苷酸标志于壳聚糖修饰的氧化铁磁性纳米颗粒（CS@MNPs）表面。培养人胰腺癌细胞株BxPC-3,实验组细胞孵育MR靶向探针Sur-MNPs,对照组细胞孵育未经壳聚糖修饰的纳米颗粒MNPs和经壳聚糖修饰的CS@MNPs,均以25μg/ml与细胞共同孵育24h。采用琼脂糖凝胶电泳检测耦联效果,采用普鲁士蓝染色观察人胰腺癌细胞对不同纳米颗粒的摄取情况,采用MTT法测定纳米颗粒对细胞的毒性作用。将标志的细胞用1%琼脂糖1ml重悬后,使用1.5TMR进行扫描,测定T2值。结果本实验成功制备了胰腺癌的特异性靶向探针。壳聚糖修饰磁性纳米粒后,透射电镜结果显示粒径大小均匀、核心粒径核心在20nm左右;琼脂糖凝胶电泳显示大部分反义核苷酸已连接到纳米颗粒表面,得到磁性靶向核苷酸。细胞普鲁士蓝染色显示未转染纳米颗粒的细胞内未见蓝色铁颗粒,而经CS@MNPs和靶向探针转染的胰腺癌细胞胞质内见大量蓝色铁颗粒分布;细胞凋亡实验显示未转染纳米颗粒、经MNPs转染和转染CS@MNPs组的细胞总凋亡率分别为34.31%、67.73%、42.88%;MTT实验结果显示经MNPs、CS@MNPs转染的细胞活力分别为46.43%、63.68%;T2WI扫描结果显示水、标志MNPs的细胞、标志CS@MNPs的细胞、孵育靶向探针的细胞的T2值分别为（331.5±18.3）ms、（219.5±21.8）ms、（218.0±17.3）ms、（171.7±32.5）ms;MRI显示标记了磁性纳米颗粒的细胞能引起T2信号下降。结论本实验成功制备了靶向人胰腺癌Survivin基因的靶向探针,该探针细胞毒性小,转染率高,体外细胞转染后可被MR检查。

英文摘要：

Purpose To prepare and construct MR molecular probe targeted on pancreatic cancer Survivin, and to investigate the feasibility on BxPC-3 cell line transfection and MR imaging. Materials and Methods The antisense oligonucleotides of Survivin was labeled to the surface of chitosan-modified magnetite nanoparticles （CS@MNPs）. BxPC-3 cell were cultured including experimental group incubated with Sur-MNPs and control group incubated with regular MNPs and CS@MNPs, 25 μg/ml for 24 boors. Agarose gel electrophoresis was used to test coupling, and Prussian blue stain for pancreatic cell uptake of nanoparticles. The toxicology of nanoparticles was explored using MTT method. After restispension in 1 ml 1% agarose gel, the labeled cells were scanned using 1.5T MR to measure T2 value. Results CS@MNPs were even in size with the diameter of the nucleus of 20 nm under transmission electron microscope. Agarose gel electrophoresis showed most antisense oligonucleotides were coupled to nanoparticles. Prussian blue stain did not demonstrate blue ion particles in non-transfected nanoparticles, while large amount of blue particles were seen in CS@MNPs and probe transfected cells. The apoptosis rate was 34.31%, 67.73% and 42.88% for non-transfected, MNPs transfected and CS@ MNPs transfected ceils respectively, with cell viability of 46.43% and 63.68% tbr MNPs and CS@MNPs cells on MTT. The T2 value for water, MNPs cells, CS@MNPs cells and Survivin targeted cells was （331.5± 18.3） ins, （219.5±21.8） ms, （218.0± 17.3） ms and （171.7±32.5） ins, respectively, indicating decreased T2 by magnetite nanoparticles. Conclusion Pancreatic cancer Survivin targeted MR molecular probe can be successfully constructed with low toxicity and high transfection rate, which can be detected by MR imaging.