【作者】 吴秋华；

【导师】 宋溪明；

【作者基本信息】 辽宁大学 ， 物理化学， 2016， 博士

【摘要】 智能型纳米药物载体可以提高药物的生物利用度,降低毒副作用,实现药物的定时、定点可控释放。本文设计合成了三种具有聚乙二醇单甲醚(MPEG)和温敏聚合物混合壳层的智能型纳米药物载体,研究了其对阿霉素(DOX)的包封、释放和细胞毒性等性质。MPEG可以提高粒子的分散性,避免纳米粒子在血液循环过程中被非特异性蛋白吞噬,提高药物到达病灶的机会。温度响应性链段在伸展状态时可以实现药物的包载,塌缩时形成核壳冠结构,提高载体的稳定性,减少药物在正常组织中的释放,核与壳之间的pH敏感连接可以实现药物的智能释放。实验结果表明,本文制备的纳米药物载体,具有刺激响应性,且释放速率可以通过混合壳中MPEG和温敏聚合物的比例来调节,具有很好的生物相容性,容易进入细胞内部,是一种具有应用前景的纳米药物载体。具体研究内容如下：1.以巯基乙醇为链转移剂,偶氮二异丁腈(AIBN)引发N-乙烯基己内酰胺(NVCL)聚合制备了端羟基聚N-乙烯基己内酰胺(PNVCL-OH),进而以PNVCL-OH和MPEG为大分子引发剂,引发丙交酯(LA)开环聚合制备了聚N-乙烯基己内酰胺-b-聚乳酸(PNVCL-b-PLA)和聚乙二醇单甲醚-b-聚乳酸(MPEG-b-PLA)嵌段共聚物,并以此为构筑单元制备了以PLA为疏水核、MPEG和PNVCL为混合壳的共聚物复合胶束(MSM),研究了胶束的温度响应性以及对阿霉素的包封和释放行为。结果表明,共聚物复合胶束在pH 7.4中性环境下,25℃时的释放速率高于37℃时的释放速率,改变混合壳中MPEG和PNVCL的比例可以改变药物的释放速率。MTT实验表明,共聚物复合胶束对HCT-116细胞毒性较小,体外细胞内吞实验表明共聚物复合胶束容易进入细胞内部。2.利用开环聚合等方法,合成了超分子共聚物复合胶束的构筑单元端尿嘧啶聚乙二醇单甲醚(MPEG-U)、端尿嘧啶聚N-乙烯基己内酰胺(PNVCL-U)和端二氨基三嗪聚己内酯(DAT-PCL)聚合物,对其结构进行了表征。利用上述聚合物,制备了以DAT-PCL为内核,MPEG-U和PNVCL-U为混合壳,基于三重氢键的超分子共聚物复合胶束(SMSM),研究了SMSM的响应行为以及对阿霉素的包封和释放性质。’H NMR和红外光谱结果证明了胶束中存在分子间氢键；动态光散射(DLS)表明胶束的粒径呈单一分布且随着疏水链段长度的增加而增大；透射电子显微镜(TEM)显示胶束形貌基本呈球形。实验结果表明,SMSM具有温度/pH双重响应性,对阿霉素包封和释放结果表明,胶束在酸性环境下(pH 5.0)的释放速率远高于中性环境下(pH 7.4)的释放速率；在pH 7.4的中性环境下,25℃时的释放速率高于37℃时的释放速率。改变混合壳中MPEG和PNVCL的比例可以改变药物的释放速率。MTT实验表明,该复合胶束体系对BGC-823细胞的毒性较小；体外细胞内吞实验表明胶束容易进入细胞内部。3.制备了介孔二氧化硅纳米粒子(MSNs),利用希夫碱反应通过亚胺键将聚乙二醇单甲醚(MPEG)和聚N-异丙基丙烯酰胺(PNIPAM)链段接枝到粒子表面,得到了具有温度/pH双重响应性的聚合物杂化MSNs粒子,对其结构进行了表征,并研究了杂化MSNs对阿霉素的包封和释放性质。结果表明,杂化纳米粒子在酸性环境(pH 5.0)下的释放速率远高于在中性环境(pH 7.4)下的释放速率；在pH=7.4中性环境下,25℃时的释放速率高于37℃时的释放速率,改变混合壳中MPEG和PNIPAM的比例可以改变药物的释放速率。MTT实验表明杂化纳米粒子对HCT-116细胞毒性较小；体外细胞内吞实验表明杂化纳米粒子容易进入细胞内部。更多还原

【Abstract】 ’Smart’drug delivery systems, which can transport and deliver drug cargo at a selected location and a specific time, can enhance bioavailability of drugs and reduce their undesirable side-effect. Three’smart’drug delivery systems with methoxy polyethylene glycol (MPEG) and a thermal-responsible polymer as a mixed shell were prepared in this paper and their properties such as drug-loaded and release, cell toxicity were studied. MPEG shell could enhance the dispersity and imparted longevity to the drug delivery systems by preventing nonspecific protein adsorptions during their circulation in vivo and enhence the opportunity to arriving at diseased site. When the thermal-responsible chain was stretching, drug loading could be complete, while it collapsing, core-shell-corona structre which could be applied to suppress burst drug release was formed. The pH-responsible link of the core and the shell could achieve smart release. The results showed that the prepared drug delivery systems were stimulis-responsive and the drug relaese amout could be adjust by the ratio of MPEG to thermal-responsible polymer. They were nontoxic and the DOX-loaded nanoparticles could be successfully internalized into cancer cells. Therefore, this kind of drug delivery systems are very promising candidates for improvements in drug delivery systems. The details are as follows:1. Poly(N-vinylcaprolactam)-b-poly lactic acid (PNVCL-b-PLA) and methoxy poly (ethylene glycol)-b-poly lactic acid (MPEG-b-PLA) block polymers were synthesized by ring openning polymerization of lactide (LA) using macroinitiators MPEG and hydroxyl-terminated poly(N-vinylcaprolactam) (PNVCL-OH), which was prepared by polymerization of N-vinylcaprolactam (NVCL) using azobisisobutyronitrile (AIBN) as a initiator and mercaptoethanol as a chain transfer agent. A mixed-shell polymeric micelles (MSMs) were prepared by self-assembly of PNVCL-b-PLA and MPEG-b-PLA in water at room temperature with PLA as the core and MPEG/PNVCL as the mixed shell. The structures of the micelles were confirmed and the drug loading and release behavor using DOX as a model drug were studied. The release rate of DOX at 25 ℃ was faster than that at 37 ℃ at pH 7.4. The drug release rate could be adjusted by the ratio of MPEG to PNVCL in the mixed shell. The low cytotoxicity of the mixed micelles was confirmed by MTT assay against HCT-116 cells and the DOX-loaded nanoparticles could be successfully internalized into cancer cells.2. Diaminotriazine-terminated poly(s-caprolactone) (DAT-PCL), uracil-terminated methoxy poly(ethylene glycol) (MPEG-U) and uracil-terminated poly(N-vinylcaprolactam) (PNVCL-U) were prepared and their structures were confirmed. The supermolecular mixed-shell polymeric micelles (SMSMs) were prepared by self-assembly of DAT-PCL, MPEG-U and PNVCL-U in water at room temperature with PCL as the core and MPEG/PNVCL as the mixed shell.’H NMR and FT IR showed that the micelles (MPEG-U or PNVCL-U…DAT-PCL) were formed based on multiple hydrogen bonding interactions. Dynamic light scattering (DLS) indicated that all of the micelles exhibit unimodal size distribution and the sizes of micelle increased with the increase of the proportion of hydrophobic segment. The morphologies of micelles visualized by transmitance electric micrography (TEM) are spherical. The SMSMs were therm/pH dual responsive. Studies on the in vitro drug release showed that the release rate of DOX at pH 5.0 was faster than that at pH 7.4 and that at 25 ℃ was faster than that at 37 ℃. The drug release rate could be adjusted by the ratio of MPEG-U…DAT-PCL2 to PNVCL-U…DAT-PCL2. The low cytotoxicity of the mixed micelles was confirmed by MTT assay against BGC-823 cells and the DOX-loaded nanoparticles could be successfully internalized into cancer cells.3. Mesoporous silica nanoparticles (MSNs) were prepared. To abtained thermo/pH dual responsive drug delivery system, two kinds of polymers, including methoxy poly(ethylene glycol) (MPEG) and thermo-responsive poly(N-isopropyl acrylamide) (PNIPAM), were covalently attached to the outlets of the mesopores, through a highly acid-sensitive benzoic-imine linker. Their structures were confirmed and the drug loading and release behavor from the hybrid-MSNs using DOX as a model drug were studied. The results showed that the release rate of DOX at pH 5.0 was faster than that at pH 7.4 and that at 25℃ was faster than that at 37℃. The drug release rate could be adjusted by the ratio of MPEG to PNIPAM in the shell. The low cytotoxicity of the MSNs was confirmed by MTT assay against HCT-116 cells and the DOX-loaded nanoparticles could be successfully internalized into cancer cells.更多还原