【作者】 郭丽霞；

【导师】 冯丽恒；

【作者基本信息】 山西大学 ， 有机化学， 2020， 博士

【摘要】 共轭聚合物是一类具有π共轭结构的有机功能材料,它不仅具有良好的光学性质,如强光捕获能力、高量子产率、良好的光稳定性,还具有能带可调、生物相容性好的优点。由其形成的共轭聚合物纳米颗粒除了上述优点外,还具备纳米颗粒的空间优势和易于修饰的特点。因此共轭聚合物及其纳米颗粒在生物传感、成像以及疾病的诊断和治疗方面被广泛研究,成为具有广阔应用前景的生物材料。细菌感染引起的疾病一直威胁人类的身体健康,尤其是耐药菌株的出现使这一问题变得更加严峻。如何有效地治疗细菌感染相关疾病,仍面临着很多问题,如革兰氏阴性菌由于具有保护性的外膜结构而较革兰氏阳性菌更难杀伤,杀伤细菌过程中因残留的活性抗生素对细菌持续刺激而产生耐药性,以及在杀灭过程中对生物正常细胞产生较大伤害等。进一步,细菌还被证明与恶性肿瘤的出现有关。以化疗为主的肿瘤治疗方法面临着严重的副作用。因此创新地提出新颖策略并发展高效抗菌和抗肿瘤材料是解决目前威胁人类公共健康的关键技术,对降低社会经济成本、提高人们生活质量至关重要。针对目前困境,本学位论文利用共轭聚合物纳米颗粒的特性和生物分子的特异性,设计并构建了一系列基于共轭聚合物的纳米自组装体,系统开展了它们在抗菌和抗肿瘤方面的应用,得到了低毒、高效杀伤细菌和肿瘤细胞的材料。主要研究内容和取得的实验结果如下:1、旨在得到高效抗菌材料,创新性地设计了具有疏水骨架和质子化伯胺盐的亲水侧链的共轭聚合物PDCP,通过自组装形成正电荷密度高和膜结合位点多的新型抗菌共轭聚合物纳米颗粒PDCP-NPs。该纳米颗粒的形貌为尺寸均一的球形,水合粒径约180 nm。基于其易吸附和强破坏细菌细胞膜的能力,该纳米材料对细菌实现高效杀灭,尤其是对革兰氏阴性菌具有高选择性的杀灭能力,且无明显的细胞毒性。此外,PDCP-NPs抗菌材料能够可视化应用于细菌成像及细菌感染的小鼠伤口的治疗,抗菌效果优于常用的抗生素,并对小鼠主要器官组织无明显损伤。本研究工作提供了一种兼容抗菌活性高,细胞毒性小的抗菌材料,为兼顾生物安全性好且高效抗菌材料的开发提供了新思路。2、基于调控策略,开发了一种生物分子调节,杀菌活性可控的共轭聚合物纳米自组装体并应用于活体细菌感染伤口治疗。利用生物相容好的小牛胸腺双链DNA和DNase I酶调节具有抗菌活性的共轭聚合物纳米颗粒CPNs-H与细菌间的相互作用,实现杀菌活性的“关闭”与“开启”。制备的含有芴和二噻吩基苯并噻二唑单元的共轭聚合物纳米颗粒能够发射红光,其表面共价连接具有抗菌活性和蓝光发射的H33258染料,所得复合抗菌材料具有双通道对细菌成像功能,可为用药量和用药次数提供依据。通过抗菌纳米颗粒与DNA自组装以及DNase I酶的解组装过程,该体系实现了对体外细菌调控杀灭,以及小鼠感染伤口的调控治疗。本研究工作提出了新的对抗耐药菌株产生的策略,发展了一种基于生物分子调控的抗菌自组装体,为解决细菌耐药性困境提供了一种简单、生物环保的方法,更为设计原位可控的杀菌体系并用于治疗细菌感染相关疾病提供了理论指导。3、利用纳米自组装技术,提出一种利用共轭聚合物优良抗肿瘤活性,借助生物分子和光来调控杀伤肿瘤的新思路。带正电荷的共轭聚合物PFFBT与显负性的天然蛋白HSA通过疏水和静电作用,形成生物相容性好的纳米自组装体PFFBT@HSA。利用相关的表征和分析手段,研究了自组装体的形貌和性质。由于HSA的介入,自组装体PFFBT@HSA比PFFBT具有更长的磷光寿命,有助于其在光照下能够高效敏化氧气产生更多的活性氧。该组装体充分利用生物分子的优势,降低了共轭聚合物的生物毒性,使聚合物PFFBT的暗毒性处于“关闭”状态,提高其生物相容性。光照后,PFFBT@HSA能够比单独PFFBT产生更多的活性氧,从而开启并增强组装体的抗肿瘤能力,达到“0+1>1”放大抗肿瘤效果。基于此,开展了该组装体在体外和活体内抑制和杀伤肿瘤细胞的相关实验,结果表明,PFFBT@HSA自组装体能够有效抑制并杀伤小鼠肿瘤细胞,且对其它器官组织未产生明显损伤。本研究工作通过生物分子和物理技术(光照)来调控基于化学分子(共轭聚合物)抗肿瘤过程,实现活体内肿瘤细胞的杀伤和肿瘤的治疗,为设计内源性分子和简单的物理技术调控药物活性提供了新的途径和实验参考。更多还原

【Abstract】 Conjugated polymers are a kind of organic functional material with large π conjugated structure.They not only have good optical properties,such as strong light capture ability,high quantum yield,good optical stability,but also possess the advantages of adjustable energy band and good biocompatibility.In addition to the advantages mentioned above,conjugated polymer nanoparticles also own the space advantages and facile modification of nanoparticles.Therefore,conjugated polymers and their nanoparticles have been widely studied in biosensing,imaging,the diagnosis and treatment of diseases.Diseases caused by bacterial infections have always threatened human health,and the emergence of drug-resistant strains has made the problem even worse.How to effectively treat bacterial infection related diseases,there are still many problems.For example,Gram-negative bacteria are difficult to kill compared with Gram-positive bacteria due to the protective outer membrane structure.Residual active antibiotic after treatment makes bacteria antibiotic,antibacterial treatment brings the damages to normal cells,and so on.Besides,bacteria are considered to trigger the formation of tumors.Since chemotherapy has serious side effects,it is urgent to develop more effective treatment.Therefore,innovative strategies and the development of effective antibacterial and anti-tumor materials are the key points to solve the current threat to human public health.It is crucial to reduce social and economic costs and improve people’s quality of life.In view of the current dilemma,in this thesis,we takes advantage of the properties of conjugated polymer nanoparticles and the specificity of biomolecules to design and construct a series of nanometer self-assembly systems based on conjugated polymer.The applications of these assemblies in antibacterial and anti-tumor therapy are systematically investigated.Corresponding materials with low toxicity and high efficiency to kill bacteria and tumor cells are obtained.The main research contents and experimental results are as follows:1.In order to obtain effective antibacterial materials,conjugated polymers with hydrophobic backbones and hydrophilic side chains of protonated primary amine salts are innovatively designed.The novel antibacterial conjugated polymer nanoparticles(PDCP-NPs)formed by self-assembly have high positive charge density and multiple membrane binding sites.The morphology of the nanoparticles is spherical with uniform size,and the size is about 180 nm.By effectively binding and destroying bacterial cell membranes,the nanomaterials can kill bacteria with no obvious cytotoxicity,especially for Gram-negative bacteria.In addition,PDCP-NPs can image bacteria and treat the bacteria infected wounds of mice.The antibacterial effect of PDCP-NPs is better than the commonly used antibiotics,and there is no obvious damage to the main organs and tissues of mice.This study provides a compatible antibacterial material with high antibacterial activity and low cytotoxicity,and proposes a new strategy for the development of high-efficiency antibacterial material with good biological safety.2.Based on the control strategy,the nano-assembly with controlled bactericidal activity mediated by biomolecules is developed and applied to the treatment of infected wounds in mice.By using calf thymus DNA and DNase I enzyme to regulate the interaction between CPNs-H and bacteria,the antibacterial activity of the assembly displays the reversible states of "closed" and "opened".The CPNs composed of fluorene and dithiophenyl benzothiadiazole unit can emit red light.The surface of CPNs is covalently modified with H33258 dye which has antibacterial activity and a blue fluorescence.The obtained composite antibacterial material has double-channel imaging capability for bacteria,which can provide a basis for the amount and frequency of medication.Through the self-assembly between antibacterial nanoparticles and DNA,and the disassembly process mediated by DNase I enzyme,the assembly shows controlled antibacterial activity and can treat infected wounds of mice in a controlled way.In this work,we propose a new strategy against drug-resistant bacteria and develop a kind of antibacterial self-assembly based on biomolecular regulation.These results also provides a simple and friendly way to solve the dilemma of drug resistance and theoretical guidance on designing in situ controlled bactericidal system for treatment of bacterial infection-related diseases.3.Based on the nano self-assembly mode,a good idea of using the anti-tumor properties of conjugated polymer,biological molecules and light to regulate the killing of tumor is proposed.Conjugated polymer PFFBT with positive charges can assembles with human serum albumin(HSA)with negative charges to form biocompatible self-assembly PFFBT@HSA by hydrophobic and electrostatic interactions.The morphology and properties of the self-assembly are studied by using related characterization and analysis methods.By introducing HSA,PFFBT@HSA has longer phosphorescence life than PFFBT,and produces more reactive oxygen species by sensitizing oxygen efficiently under light.The assembly makes full use of the advantages of biomolecules,which can reduce the biotoxicity and make the dark toxicity in the “off” state.After irradiation,PFFBT@HSA can generate more reactive oxygen species than PFFBT,which enhances the anti-tumor ability of assembly and achieves the anti-tumor of "0+1>1" amplification effect.Therefore,relevant experiments are carried out to inhibit and kill tumor cells in vitro and in vivo.The results show that PFFBT@HSA can effectively inhibit and kill tumors in mice without causing obvious damage to other organs and tissues.In this work,biological molecules and physical technique(light)are used to regulate the anti-tumor process of conjugated polymers,the results provide a new approach and experimental reference for the design of controllable drug activity by using endogenous molecules and simple physical techniques.更多还原