【作者】 李晓丽；

【导师】 李斌；

【作者基本信息】 东北林业大学 ， 林产化工， 2012， 博士

【摘要】 磷腈,由磷、氮单双键交替形成的一种无机大分子骨架,磷原子上易于发生亲核取代反应。由于结构设计的灵活性,性能的多样性、可调性,材料的稳定性、生物可降解性等诸多特性,磷腈在诸多领域具有深入研究开发价值和广阔的应用前景。尤其是磷腈侧臂上引入不同结构和比例的取代基可有效地调节聚合物的水解性能、生物相容性能、生物降解性能,这使得它在控制药物释放、组织工程等生物医学领域成为极具开发潜力的材料。本论文以环三磷腈为研究对象,设计合成了两种类型的环三磷腈,一种是疏水性环三磷腈,即六色氨酸乙酯苯氧基环三磷腈(HEPCP)和六甘氨酸甲酯苯氧基环三磷腈(HGPCP);另一种是两亲环三磷腈：MMPCP,侧链分别为疏水端甘氨酸甲酯和亲水段聚乙二醇单甲醚(Mw=5000); EMPCP,侧链为疏水端色氨酸乙酯和亲水段聚乙二醇单甲醚(Mw=1000)。采用FT-IR、GPC、MS、NMR等手段对结构进行了表征；采用DSC、TGA、UV、LS、CLSM等方法分析了产物的结晶形态、热稳定性、水解性能和荧光特性；采用透析法、乳化法和反相溶剂技术研究了不同结构的环三磷腈在溶液中的自组装行为；并通过自组装制备了两亲环三磷腈负载抗肿瘤药物姜黄素的体系,构建了多功能载药平台。通过UV和TGA分析发现,四种环三磷腈衍生物都是热稳定性良好的可降解的生物友好材料；DSC和XRD实验表明HEPCP和HGPCP是无定形态的,而MMPCP和EMPCP由于MPEG链段的有序排列而具有一定的结晶形态；LS和CLSM观察表明HEPCP和HGPCP都有荧光特性,而且可进行细胞成像；细胞毒性试验显示MMPCP和EMPCP的细胞毒性具有浓度依赖性,在浓度较低时毒性较小,荧光显微镜观察MMPCP和EMPCP都分布在除细胞核外的细胞质和其他细胞器中。疏水性环三磷腈HEPCP和HGPCP通过反相溶剂技术可以获得自组装纳米粒子。所制备纳米粒子的形貌采用SEM和TEM进行观察,并分析了影响组装体形貌的因素；纳米粒子的粒径分布和尺寸稳定性分析用动态光散射仪(DLS)测定；实验结果表明：两种自组装纳米粒子都是表面光滑的规则球形结构,荧光特性较组装前都明显增强,纳米粒子在溶液中储存都可以发生二次组装,因此适合冻干保存。疏水性环三磷腈的自组装过程可通过临界水含量(cwc)实验分析,其自组装机制采用结构模拟和理论计算并结合实验现象加以阐明。HEPCP自组装纳米粒子的热稳定性增强,cwc值在临界溶液浓度以上,与溶液浓度无关。其自组装过程可阐述如下：由于HEPCP在水中不溶,当溶液中的水含量达到临界值时,体系中形成的微小的W/O空间内,在某一临界浓度以上,每个微小空间内HEPCP分子间距离达足够小,分子间通过疏水的分子间作用力驱动实现有序堆积的自组装过程。然而HGPCP自组装纳米粒子的热稳定性下降,cwc值与溶液浓度相关,且在极稀的溶液中可以实现自组装。HGPCP自组装过程的可能机制是在水分子的参与下,HGPCP分子在分子间氢键的诱导下的有序堆积。两亲环三磷腈MMPCP,由于MPEG链段较长,甘氨酸甲酯和环三磷腈短臂的酰胺键与水之间形成氢键作用,在水中溶解性良好,通过乳化技术在油水界面可以成功包载疏水性的抗肿瘤药物姜黄素,实现姜黄素的增溶、EPR靶向、缓释的功能。EMPCP通过透析法自组装形成球形纳米粒子,也可以和姜黄素通过分子间作用组装成纳米载药微球,载药微球的粒径变小,尺寸分布较窄。多元醇法制备的四氧化三铁纳米粒子具有良好的水溶性,胶体稳定性,磁共振成像(MRI)优异性能。TEM和磁性能实验证明两亲环三磷腈成功地将磁性纳米粒子和姜黄素包载,可构建具有磁靶向、磁共振成像、EPR效应、荧光示踪功能的多功能载药平台。更多还原

【Abstract】 Polyphosphazenes, macromolecules with an alternative phosphorus and nitrogen backone, provide an ideal background and open the door to a wide range of useful materials for advanced technology, which are among the most versatile of all polymers. This is a consequence of the unique properties of the phosphorus-nitrogen backbone and the ease with which a wide range of different side groups can be introduced mainly by macromolecular substitution and secondary substitutions. This field has reached a stage where the fundamental chemistry now allows the design and synthesis of a broad range of new materials that are valuable for fine-tune properties through different side groups or combinations of groups that led to the development of numerous biomedical initiatives.In this thesis, two types of cyclotriphosphazenes have been synthesized. One type is the hydrophobic cyclotriphosphazenes, such as hexa-[p-(carbonyl tryptophan ethyl ester) phenoxy)] grafted cyclotriphosphazene (HEPCP) and hexa-[p-(carbonyl glycin methyl ester) phenoxy)] substituted cyclotriphosphazene (HGPCP). Another type is the amphiphilic cyclotriphosphazenes, which is grafted with hydrophobic glycin methyl ester and hydrophilic MPEG5000chain with ratio of4:2(MMPCP) and inarched with hydrophobic tryptophan ethyl ester and hydrophilic MPEG1000chain with ration of3:3(EMPCP). The structures of such four products are confirmed by FT-IR、GPC、MS、NMR, and the thermal stability, hydrolysis and fluorescent properties are further researched by DSC、TGA、UV、LS、 CLSM. The self-assembly of cyclotriphosphazenes with different structure has been achieved by dialysis, emulsification and desolvation methods, respectively. Also, the multi-functional drug-loaded platform is fabricated by self-assembly of amphiphilic cyclotriphosphazenes, curcumin and magetic nanoparticles of Fe3O4.It is shown by UV and TGA analysis that the synthesized cyclotriphosphazenes are thermal stability and biodegradable. It is also illustrated by DSC and XRD results that both the hydrophobic HGPCP and HEPCP are amorphous structure, and the amphiphilic cyclotirphosphazenes of MMPCP and EMPCP are partially crystalline due to the substitution of MPEG chain. The fluorescent property of hydrophobic cyclotriphosphazenes is explored by LS and both HGPCP and HEPCP exhibit strong fluorescent emission which is easily observed by CLSM. The cell toxicity is also examined for amphiphilic cyclotriphosphazenes, and the results show that the cell toxicity are depended on the concentration of MMPCP and EMPCP, which are distributed in cytoplasm and organelle.The nanoparticles have been fabricated through self-assembly of hydrophobic cyclotriphosphazenes such as HGPCP and HEPCP by desolvation method. The morphology of the nanoparticles is observed by SEM and TEM, and the influence of reaction conditions on the self-assembly process is also explored. The particle size distribution and stability are studied by DLS. All the experimental results show that the self-assembly aggregations from hydrophobic cyclotriphosphazenes are uniform and spherical nanoparticles with smooth surface, exhibiting strong fluorescent emission. It has been found that the nanoparticles in solution could lead to secondary assembly to form nanoparticles monolayer which is indicative of lyophilization for the nanoparticles.The self-assembly process of hydrophobic cyclotriphosphazenes is explored by critical water content (cwc) experiments, and the mechanism is clarified based upon the experimental results with connection of the theoretical and structure simulation. The thermal stability of HEPCP nanoparticles is increased, and the cwc value for self-assembly of HEPCP should be above the solution concentration while which is independent with solution concentration. The self-assembly mechanism of HEPCP is proposed as follows:when the water content is reached to cwc, numerous micro-W/O-system are formed due to the HEPCP molecule is not dissolved in water which is shortened the distance between HEPCP molecule. As the water content is increased up to cwc, the molecular distance was shortened enough to lead to the HEPCP aggregation induced by intermolecular noncovalent interactions. While the thermal stability of the HGPCP nanoparticles is decreased, and the the cwc value for self-assembly of HGPCP is also related to the solution concentration. The self-assembly of HGPCP could be processed even though at diluted solution, which is indicated that the self-assembly of HGPCP molecules to nanoparticles was driven by the intermolecular hydrogen bonds with participation of water molecule.The hydrophobic anti-cancer curcumin can be encapsulated by amphiphilic cyclotirphosphazenes of MMPCP through emulsification because the formation of hydrogen bonds between the amide bonds on the glycinmethylester and cyclotirphosphazene arm and water molecule. Such technique could be fabricated the multi-functional drug-carriers such as dissolution improvement, EPR-targeting and drug-release. The nanoparticles have been also self-assemblied from EMPCP through dialysis method, which is further interacted with curcumin to form drug-loaded nanoparticles. The particle size of EMPCP drug-loading nanoparticles is decreased with narrow size distribution.The magnetic nanoparticles of Fe3O4synthesized by polyol process can easily be dispersed in water media with excellent colloid stability and MRI enhancement effect. It is confirmed by TEM and magnetic measurement that the magnetic nanoparticles and curcumin can be simultaneously capped by amphiphilic cyclotirphosphazenes. Thus, a multi-functional drug-loading platform, with guided delivery by outside magnetic field, MRI imaging, EPR effect, fluorescent tracing, is constructed by interaction between MPEG in amphiphilic cyclotriphosphazene and polyol on the surface of Fe3O4.更多还原