【作者】 祁秀秀；

【导师】 路建美；

【作者基本信息】 苏州大学 ， 应用化学， 2013， 博士

【摘要】 随着现代人类生活环境及生活方式等诸多因素的影响，癌症发病率正逐年增高，而癌症的诊断及治疗却一直是医学界亟待解决的难题。虽然人们已经陆续开发出一些具有良好药效的药物，但大多存在着同样的问题：缺乏对肿瘤的特异性，导致在临床应用中产生严重的毒副作用。因此，实现抗癌药物专一性选择性地作用于肿瘤细胞成为当今生物医学相关领域的研究热点及焦点。本论文主要针对目前抗肿瘤药物载体药物输送效率、智能化以及材料安全性等问题设计并合成了一系列基于两亲性聚合物的智能型药物控释体系。此类载体的优势在于，药物载体本身具有良好的稳定性并能在到达肿瘤部位后在其内部弱酸环境刺激下控制释放所负载的药物。同时，这些体系能选择性地对肿瘤细胞或组织产生抑制作用而对正常细胞或组织具有良好的安全性。（1）设计合成了一种含肉桂醛缩醛结构的pH-敏感亲油性单体SDMA，将其与亲水性单体OEGMA通过自由基共聚的方法合成了pH-敏感两亲性聚合物PSO，在中性的水溶液中能自组装成平均粒径为130nm左右的聚合物胶束。对其进行体外细胞实验，发现在肿瘤细胞的微酸环境中聚合物侧链上对酸不稳定的环状缩醛结构会发生水解，释放出的肉桂醛小分子对人黑素瘤A375细胞株具有抑制存活的作用。此外，在体外细胞实验中我们还发现，pH敏感的PSO聚合物胶束可以作为药物载体包裹模拟药物尼罗红进入小鼠黑素瘤细胞B16，并在肿瘤细胞的酸性环境中迅速释放。（2）为了有效提高载药量并增加胶束纳米粒子的稳定性，我们将两亲性聚合物与中空介孔二氧化硅纳米粒子复合，构建了多功能核-壳型纳米复合物。首先将含肉桂醛缩醛结构的pH敏感的亲油性单体SDMA、亲水性单体OEGMA及含有红色荧光发色团的罗丹明单体通过简单的自由基共聚得到多功能的两亲性共聚物PSOR，接着通过简单的自组装将其包裹在经C18修饰的中空介孔二氧化硅（HMS@C18）表面，得到核-壳型多功能纳米复合物（HMS@C18@PSOR）。利用该结构的空腔可以负载抗癌药物阿霉素。本体系不仅有较高的载药能力，而且能通过HMS表面覆盖其孔道的PSOR在肿瘤细胞中的弱酸环境下的pH-响应水解达到药物控制释放的目的。同时水解释放出来的小分子肉桂醛能够选择性地抑制人黑素瘤细胞A375。相对而言，该纳米复合物对人正常成纤细胞GM几乎没有毒性。此外该纳米复合物由于含有罗丹明结构还可用于荧光细胞成像。（3）在上述核-壳型纳米复合物的结构基础上，我们进一步优化壳层聚合物的结构，设计了具有荧光发色团的引发剂DIA，并依次引发亲油性单体SDMA和亲水性单体OEGMA，通过ATRP方法合成了结构更可控的多功能两亲性嵌段共聚物（PSDMA-b-POEGMA），然后与带有长烷基链的中空介孔二氧化硅（HMS@C18）自组装形成了pH-敏感的核-壳型纳米粒子（HMS@C18@PSDMA-b-POEGMA），用于药物的负载和控制释放。该纳米粒子对抗癌药物阿霉素（DOX）具有较高的负载能力，并能在肿瘤细胞弱酸性环境中实现药物的控制释放；与此同时释放出来的肉桂醛能抑制人黑素瘤细胞A375生长，相对于人正常成纤细胞GM而言，该纳米复合物载体几乎没有毒性。此外，纳米粒子表面所包裹的聚合物中含有引发剂的荧光链段，可用作细胞的荧光造影。（4）为了得到粒径更适合于临床使用的的超小纳米粒子，设计合成了含有双羧基螯合基团的两亲性低聚物，通过自组装得到粒径在10nm左右的聚合物胶束，其亲油性内核为低聚苯乙烯，亲水性外壳为EDTA结构的一半（—N(CH2COOH)2）。利用该结构与顺铂的螯合作用，可以方便地得到表面负载铂的聚合物胶束。因为双羧基结构是通过RAFT试剂引入到聚合物链端的，因此顺铂与聚合物胶束的作用几乎是化学计量的。基于胶束的药物载体对于顺铂具有较高的载药效率。因为该负载铂体系（PS(COOH)2-Pt）在弱酸性条件下可释放出铂，所以能够选择性地在肿瘤细胞中释放出铂。在体外细胞实验和体内实验中，该体系比游离态的顺铂具有更强的对肿瘤细胞Sk-Br3的抑制作用；并且无论药物载体，还是载体-铂的纳米复合物体系，都没有明显的系统毒性。（5）上述基于两亲性聚合物的功能材料除了在生物应用领域有良好的应用前景以外，由于其结构方面的优势，经与磁性纳米粒子组装后还可用于水处理：将端基功能化的两亲性低聚物通过简单的自组装方法修饰在亲油性的单分散四氧化三铁超顺磁纳米粒子表面，得到的超顺磁纳米复合物在水中能很好地分散，因其表面官能团双羧基能与汞离子迅速发生作用，能在非常低的磁场梯度下快速有效地除去水中低浓度的汞离子。更多还原

【Abstract】 The incidence of cancer is growing increasingly because of the living environment and lifestyle of modern people. However, the treatment of cancer was still difficult to overcome.Some drugs with good therapy efficacy have been developed and applied in clinic, butmost of them lack of specific pharmacological effects and show serious side effects. As aresult, how to achieve selective efficacy of drugs on tumor cells and tissues has attractedthe attention in the biomedical research field. In this thesis, we fabricated a series ofintelligent drug delivery systems based on amphiphilic polymers to resolve problemsincluding low drug loading capacity, functionality limitations, safety issue, and so on. Ournamomaterials could accumuate in tumor sites and realize controlled release. Besides,theses systems would selectively inhibit the proliferation of cultured tumor cells or tissues,in comparison, show negligible toxicity in normal cells or tissues.(1) The pH-responsive amphiphilic copolymer poly(SDMA-co-OEGMA)(PSO) wasprepared from the pH-sensitive hydrophobic monomer2-styryl-1,3-dioxan-5-ylmethacrylate (SDMA) and the hydrophilic monomer oligo(ethylene glycol) methyl ethermethacrylate (OEGMA) by radical polymerization. Polymeric aggregates with about130nm diameter were obtained by the self-assembly of PSO in neutral aqueous solution.Cinnamic aldehyde (CA) small molecules are broken away from PSO side chains after thehydrolysis of acid-labile cyclic acetal in cultured A375human melanoma cells and furthersuppress the proliferation of this kind of tumor cells. Furthermore, the PSO aggregate wasdemonstrated to be a drug carrier for encapsulating Nile Red as model drug in in vitrotesting. Based on the pH-responsive characteristic, the Nile Red molecules loaded inself-assembly process could be released from the aggregate inside cultured B16mousemelanoma cells.(2) In order to improve the drug loading content and stability of carriers, amultifunctional nanocomposite (HMS@C18@PSOR) was synthesized by assembling hollow mesoporous silica nanoparticles (HMS) and as-sythesized pH-sensitive amphiphiliccopolymer from rhodamine chromophore, hydrophobic monomer SDMA, hydrophilicmonomer OEGMA. The obtained nanocomposites have high drug loading content due tothe HMS core, selectively release the encapsulated drug in mild acidicendosomal/lysosomal compartments as a result of the degradation of the pH-resposivepolymer PSOR, and also selectively inhibit the proliferation of cultured A375humanmelanoma cells by cinnamic aldehyde from pH-degradation of PSOR. In addition, thenanocomposites have potential of optical imaging in live cells.(3) Based on the core-shell nanocomposite mentioned above, we fabricated a novelmultifunctional nanocomposites (HMS@C18@PSDMA-b-POEGMA) consisting of HMSand well defined amphiphilic capping agent. The first step was the synthesis of amphiphilicblock polymer (PSDMA-b-POEGMA), by atom transfer radical polymerization frominitiator with a chromophore, hydrophobic monomer SDMA, hydrophilic monomerOEGMA. The second step was the self-assembly of amphiphilic polymer and hydrophobicHMS modified with C18, and the obtained multifuctional nanocomposites could be welldispersed in aqueous solution, have high drug loading content. After uptake by A375human melanoma cells, the pH-responsive shell would hydrolized due to cleavage of acetalmoieties in the weakly acidic endosomal/lysosomal compartments, resulting in loaded drugrelease. Furthermore, the simultaneously released cinnamic aldehyde (CA) would inhibitthe proliferation of cultured A375human melanoma cells. In comparison, thenanocomposites show negligible toxicity in GM human normal fibroblast. In addition, thenanocomposites have potential of optical imaging in live cells due to chromophores fromamphiphilic block polymer.(4) In order to obtain ultra small nanocomposite more suiltable for clinic application,polymeric micelles (~10nm) have been prepared from the amphiphilic oligomercomprising of oligomeric polystyrene as the hydrophobic inner core and half of EDTA(-N(CH2COOH)2) as the hydrophilic outermost shell. After chelating cisplatin with-N(CH2COOH)2in water, polymeric micelles containing Pt on the spherical surface havebeen easily obtained. Since the chelate group is introduced into amphiphilic oligomer asthe terminal group by RAFT agent, the chelation of cisplatin with PS(COOH)2is almoststoichiometric. The drug carrier based on PS(COOH)2showed a high loading efficiencytowards cisplatin. The release of the therapeutic Pt from the cisplatin-loaded composites (PS(COOH)2-Pt) triggered under weak acidic conditions resulted in good Pt-releasing andaccumulation in tumor cells. Both in vitro and in vivo, the chelated cisplatin inhibitedSk-Br3cancer more effectively than the intact cisplatin do. Furthermore, neitherPS(COOH)2nor PS(COOH)2-Pt showed obvious systematic toxicity.Based on the above works, we further studied the potential applications of amphiphilicpolymer and iron oxide in water treatment materials.(5) Bifunctional oligomers were synthesized and could be easily used to coatmonodisperse hydrophobic magnetite (Fe3O4) superparamagnetic nanoparticles (MSPNPs).And the resulting hydrophilic modified MSPNPs (M-MSPNPs) with abundant groups onthe surface, which could bond with Hg ions, could be used in the fast, efficient removal ofHg ions from water samples by low-field magnetic separation.更多还原