【作者】 郭艳霜；

【导师】 常津；

【作者基本信息】 天津大学 ， 材料学， 2004， 硕士

【摘要】 采用自乳化/溶剂挥发法制备了包载卡氮芥的聚乳酸纳米微粒(BCNU-PLANPs),扫描电子显微镜、透射电子显微镜、激光粒度仪等表征显示,纳米微粒呈表面光滑的球形,粒径较小且分布均匀,分散性好。制备工艺条件,如滴加方式、油相配比、聚乳酸浓度及乳化剂浓度等,对纳米微粒粒径及产率均有影响,在实验范围内最佳制备方法为:油相配比丙酮/乙醇:6:4、聚乳酸浓度为2%、乳化剂浓度为0.5%。采用显色法测定纳米微粒的载药率及包封率,考察了初始投药量、聚乳酸相对分子质量和挥发时间对微粒载药率和包封率的影响,纳米微粒的最高载药率和包封率分别为5.63%和33.45%。结合考虑纳米微粒的粒径、形态、产率、载药量及包封率,选择最佳制备方案为:初始投药比(BCNU/PLA)为1:5;聚乳酸相对分子质量为10 000,30 000和50 000;微球制备时间为5小时。载药纳米微粒的体外释药实验表明,聚乳酸纳米微粒具有药物缓释特性,且随聚乳酸相对分子质量减小,药物释放速度加快,突释现象明显。体外胶质瘤细胞抑制实验显示:空载微粒对肿瘤细胞没有抑制作用,显示出载体材料良好的生物相容性,载药纳米微粒对C6鼠胶质瘤细胞的抑制率等于或大于游离药物,且具有缓释抑制特性。以荷瘤鼠为模型的动物实验表明:无论是早期治疗还是晚期治疗,与对照组及原药治疗组相比,载药纳米微粒能有效的抑制胶质瘤细胞的增值,显示了较强的细胞毒性,显著提高了实验动物的生存期。尤其是在大剂量早期治疗中,一只荷瘤鼠肿瘤消失并长期存活,其余大鼠平均存活期为24.3天,存活期平均延长88.37%。另外,实验还证明空白微球有较好的体内生物相容性。在以上实验基础上,采用同种方法制备了表面修饰转铁蛋白的聚乳酸纳米微粒(Tf-PLA NPs),以X-光电子能谱对其表面结构进行了表征。荧光相差倒置显微镜观察显示纳米微粒表面的转铁蛋白具有活性,纳米微粒可进入细胞胞浆,具有瘤细胞靶向性。以99mTc放射性标记纳米微粒,SPECT观察不同途径给药后纳米微粒体内分布,结果显示:鼠尾静脉注射后纳米微粒主要浓集于腹腔的肝和脾;颈动脉注射后在腹腔脏器存在分布,颅内分布显著提高;立体定位注射后纳米微粒滞留于颅内,在外周器官未观察到放射活性。更多还原

【Abstract】 BCNU-loaded poly(D,L-lactic acid) nanoparticles ( BCNU-PLA NPs) wereprepared with spontaneous emulsification /solvent extraction method. SEM and TEMshowed that NPs with small particle size and narrow size distribution, which hadspherical geometry had been acquired. In order to find the optimum prepare condition,some factors that influence the formation of NPs such as preparation method, oilphase, concentration of PLA, emulsification concentration were studied.Bratton-Marshall colorimetric method was used to determine the drug content andthe influence of initial BCNU content, molecular weight of PLA and stirring time ondrug encapsulation efficiency were evaluated. The highest drug loaded ratio and drugencapsulation efficiency of NPs were 5.63% and 33.45%, respectively. Take intoaccount of the geometry, yield, size, and drug encapsulation efficiency of NPs, wedetermine the ratio of BCNU to PLA 1:5, MW of PLA 10 000, 30 000, 50 000,stirring time 5 hours as the optimum prepare condition. The study of in vitro drug release behavior demonstrated that BCNU-loaded PLANPs had shown certain sustained release characteristics. The NPs with low molecularweight of PLA showed higher burst effect and significantly faster release of drugfrom PLA samples. The results of cytotoxicity test demonstrated that drug-loadedNPs had higher antitumor activity, compared with free BCNU, and sustained drugrelease character was achieved as well. In addition, it appeared that the empty NPsbarely exerted effect on the growth of cells. This demonstrated that the matrix hadlow cytotoxicity and good biocompatibility.Inhibition of tumor growth in vivo of the nanoparticles was investigated bytumor-bearing animal model. The results showed that BCNU-loaded PLA NPs hadstronger cytotoxicity and prolonged the average survival time of rats. Especially whentreated at the early time with higher dosage of NPs, the average survival time of ratswere prolonged 88.37%, furthermore 1 rat kept normal behavior continuously up to 60days of observation period.PLA nanoparticles coated with transferrin were prepared with the same methodmentioned above. The activity of transferrin was remained and the NPs showedglioma cell-targeting ability. The biodistribution of Tf-coated nanoparticles wasfurther investigated by 99Tc-labeled SPECT. The results showed thatsurface-containing transferrin PLA nanoparticles were concentrated mainly at liverand spleen after intravenous injection. When administered with carotid injection, thebrain uptake of surface-containing transferrin PLA nanoparticles was remarkableincreased. After injected the nanoparticles stereotacticaly, the radioactivity could bedetected only in rat brain and no radioactive foci outside the brain could be found.更多还原