【作者】 马平安；

【导师】 张丽萍； 景遐斌；

【作者基本信息】 东北师范大学 ， 生物化学与分子生物学， 2010， 博士

【摘要】 糖作为人体能量的载体和重要的生物信息分子在许多重要的生理过程中发挥着至关重要的作用,并且可以通过与蛋白质的特异性识别控制生物信息的传递。研究发现了乳糖(半乳糖)与只存在于哺乳动物肝细胞表面的乳糖(半乳糖)受体特异性的识别和结合的特性。利用该特性,制备含有乳糖(半乳糖)的聚合物给药载体,实现肝脏的主动靶向给药,越来越受到广泛的关注。脂肪族聚酯(如聚乳酸)以其良好的生物相容性、生物降解性、低免疫原性、可加工性和机械强度成为当今应用最广泛的生物医用材料之一,已经被用于药物控制释放体系的载体、手术缝合线和组织工程支架材料。尽管如此,聚乳酸在应用过程中仍然存在以下问题:1)由于与细胞缺少足够的相容性,植入体内后可能导致发炎及免疫反应;2)由于缺少官能团,很难进行化学修饰;3)亲水性差。针对这些问题,本文用亲水性极好、无毒、无免疫原性的聚乙二醇改善其亲水性和生物相容性;通过与氨基酸NCA单体或者功能化的碳酸脂六元环单体共聚,一方面改善材料的生物相容性、生物降解性和理化性质,另一方面,在聚合物链上引入了活性官能团,并通过这些官能团将乳糖分子以及抗癌药物分子引入到聚合物的体系中,通过纳米自组装技术制备肝靶向的高分子键合药,并深入的研究了该类型药物载体在生物学上的应用。具体研究内容如下:1.合成了带有巯基的乳糖糖苷和聚乳酸-聚半胱氨酸(PLLA-PLC),并利用巯基,将乳糖分子引入到聚合物的亲水段,得到了含糖聚合物PLLA-PLC/Lactose,通过核磁共振(1H NMR)、红外光谱(FT-IR)等手段对聚合物结构进行了表征。接触角实验证明了接枝乳糖后材料的亲水性得到了改善;体外细胞培养证明了聚合物具有良好的生物相容性;激光共聚焦显微镜(CLSM)和表面等离子体共振(SPR)技术证明了合成的含乳糖材料对蓖麻凝集素(RCA)具有特异性识别和结合的作用。纳米自组装技术制备了胶束,通过场发射扫描电子显微镜(ESEM)、动态光散射(DLS)、荧光光谱等方法测定了含糖聚合物胶束的表面形貌、粒径大小及分布、临界胶束浓度等各项性质。2.合成了带有叠氮基的乳糖和带有叁键的双亲性高分子PEG-PMPC-PLA,并通过“Click”反应将乳糖引入到聚合物的疏水段,得到含糖聚合物PEG-PMPC/Lactose-PLA,体外细胞培养技术证明了材料良好的生物相容性;合成含羟基的双嵌段共聚物PEG-P(LA-DHP),通过羟基将抗癌药物引入到聚合物的疏水段,得到键合药物高分子PEG-P(LA-DHP/Dox)。通过纳米自组装技术,将两种聚合物分子按一定比例混合,制备了含糖载药混合纳米胶束,通过ESEM、DLS等方法测定了含糖聚合物胶束的表面形貌、粒径大小及分布等;激光共聚焦显微镜观察了肝癌细胞对含糖胶束的特异性吞噬,证明了乳糖受体介导的内吞作用;MTT法考察了该靶向键合药物胶束的细胞毒性。3.合成了氨基化的双嵌段共聚物NH2-PEG-PLLA,并通过氨基将乳糖引入到聚合物的亲水端,考察了该含糖材料与蓖麻凝集素特异性结合的作用;通过聚合物PEG-P(LA-DHP)的羟基引入了荧光标记物/模式药物罗丹明B;考察了两种材料的生物相容性;将两种聚合物材料按照一定的比例混合,制备了多功能混合纳米胶束,通过ESEM、DLS、荧光光谱等方法测定了含糖聚合物胶束的表面形貌、粒径大小及分布、临界胶束浓度等;通过激光共聚焦显微镜及流式细胞术分别考察了肝癌细胞对含糖胶束的特异性吞噬作用;通过尾静脉注射的方式将胶束溶液分布到小鼠体内,给药不同时间后将小鼠处死,利用CRI活体成像系统和激光共聚焦显微镜等手段考察了含糖胶束在体内的分布情况(包括小鼠的离体器官、冰冻组织切片、组织匀浆液),结果表明该多功能混合胶束体系具有显著的肝靶向效应。4.应用上述2、3中含糖材料与键合药物高分子PEG-P(LA-DHP/Dox)制备了混合胶束,考察了载药胶束小鼠体内抗肿瘤活性,包括给药后瘤径(瘤体积)的变化、体重的变化等。更多还原

【Abstract】 As the energy carrier and important biological information molecules, sugar plays a crucial role in many important physiological processes, and also controls the transmission of biological information through their specific recognition with the protein. It has been found that the lactose (galactose) has specific recognition and binding characteristic with lactose (galactose) receptor that exists on the surface of mammalian liver cells. By virtue of this property, drug delivery carriers containing lactose (galactose) to achieve active targeting have received more and more attention.Aliphatic polyester (such as polylactide), one of the most important biodegradable materials in biomedical application, has been widely used in carriers in drug delivery, sutures and temporary matrixes or scaffolds in tissue engineering due to its biodegradability, good biocompatibility, high mechanical properties and excellent shaping and molding properties. However, the following factors limit its applications: 1) their lack of adequate interactions with cells, leading to unexpected foreign body reactions in vivo; 2) the difficulty in their modification because they do not contain any reactive groups; 3) their low hydrophilicity. In this thesis, we attempt to improve the hydrophilicity and biocompatibility of polylactide by introducing poly(ethylene glycol), a molecule that is hydrophilic, nontoxic, biocompatible and nonimmunogenic. By introducing aliphatic carbonate monomers, the biocompatibility, physicochemical properties and biodegradability can be adjusted. What’s more, with this method many kinds of reactive groups can be introduced into the polymer for futher conjugation with drug and sugar molecules. Targeted nano-micelles were prepared by self-assembling these amphiphilic polymers. Their applications were investigated. Detailed studies are as follows:1. A novel block copolymer PLLA-PLC carrying pendant thiol groups was designed and synthesized. The lactose molecules were introduced into the hydrophilic segment (PLC) of the polymer, obtaining PLLA-PLC/Lactose. The polymers were characterized by 1H NMR and FT-IR. Contact angle results proved the improved hydrophilicity by lactose grafting; in vitro cell culture verified their good biocompatibility; laser scanning confocal microscope (CLSM) and surface plasmon resonance (SPR) technology demonstrated specific recognition and binding effect between lactose-containing polymer and ricin agglutinin (RCA). Environmental Scanning electron microscopy (ESEM), dynamic light scattering (DLS), and fluorescence spectroscopy were used to characterize the morphology, particle size and distribution, critical micelle concentration of the sugar-containing polymer micelles, respectively.2. Lactose was azidized and alkynyl containing amphiphilic block copolymer PEG-PMPC-PLA was prepared. Then lactose was introduced into the hydrophobic segment of PEG-PMPC-PLA via Cu(I) catalyzed alkynyl-azide cycloaddition reaction (click chemistry). In vitro cell culture verified their good biocompatibility. Hydroxyl carrying copolymer PEG-b-P(LA-co-DHP) was synthesized. The anticancer drug doxorubicin was conjugated to the P(LA-co-DHP) segment, obtaining PEG-P(LA-DHP/Dox). Mutifunctional micelles were prepared by co-assembling method. ESEM, DLS characterized the morphology, particle size and distribution of the nano-micelles. Laser confocal microscope confirmed lactose receptor-mediated endocytosis. MTT method indicated the cytotoxicity of Dox-conjugated micelles.3. On the one hand, block copolymers with lactose conjugated at the segment PEG, lactose-PEG-PLLA, was prepared. Its specific binding effect with RCA was demonstrated. On the other hand Rhodamine B labeled block copolymer was synthesized. Mutifunctionalized micelles were prepared by co-assembling the two copolymers. ESEM, DLS and fluorescence spectroscopy characterized the morphology, particle size and distribution of the nano-micelles. Laser confocal microscope confirmed lactose receptor-mediated endocytosis. The micelles were injected into mice via tail vein injection. At specific time intervals, the mice were sacrificed and the in vivo distribution of the micelles solution was investigated by CRI in vivo imaging systems and laser scanning confocal microscope. The results showed obvious liver targeting effect.4. The in vivo anti-tumor activity of lactose targeting, drug conjugated micelles PEG-P(LA-DHP/Dox) was investigated, including tumor diameter, body weight change and life cycle variation after drug administration.更多还原