海藻酸钠-石墨烯基结肠靶向给药系统构建及门脉联控化疗机制研究

The cancer cell is easily spread to liver after the operation treatment of colon cancer. The colon-specific sustained-release drug delivery system is expected to solve many technical problems of conventional "hepatic portal venous catheter chemotherapy". However, many problems are currently existed, such as the poorly effective control of release rate, inaccuracy of positioning, easy influence by microenvironment and poor stability. In this project, we construct a new type of colon-specific drug delivery system based on sodium alginate-graphene by loading the chemotherapy drug on the carrier of sodium alginate-modified graphene, which has characteristics like positioning adhesion of colon, high safety, joint control of drug release rate of hepatic portal vein, high capacity of drug loading, etc. Moreover, the compositional structure among graphene oxide, butanediamine-grafted sodium alginate and chemotherapy drug and the influence rule of cross-linking, reduction and drug-loading process on the compositions, structures and morphologies of carrier and drug delivery system are studied systematically to obtain the carrier and drug delivery system with controllable structures; Furthermore, the inner relationship between composition and structure of drug delivery system and its physical and chemical property, colon targeting, adhesion, biological toxicity, portal vein-joint controlled release and inhibition effect on colon cancer spread to liver is also studied to clarify the mechanism of portal vein-joint controlled chemotherapy of drug delivery system; then, based on the research of the constructed of animal models, a jointly controlled drug delivery system which owns obvious inhibition effect on colon cancer spread to liver was established. The result of this study is helpful to improve the basic research level of our colon-specific sustained-release drug delivery system, and offers a new approach and idea for the treatment of colon cancer spread to liver.

结肠癌术后癌细胞易肝转移，结肠靶向缓释给药系统有望解决常规"肝门静脉置管化疗"的诸多技术难题，但目前存在释药速率无法有效控制、定位不精确、易受微环境影响和稳定性差等问题。本项目通过在海藻酸钠修饰石墨烯载体上负载化疗药物，构建新型海藻酸钠-石墨烯基结肠靶向给药系统，具有结肠定位粘附、安全性高、肝门静脉释药速率可联控和载药量大等特点。系统研究氧化石墨烯、丁二胺接枝海藻酸钠和化疗药物的组成结构，交联、还原及载药工艺对载体及其给药系统的组成、结构和形态的影响规律，获得结构可控的载体及其给药系统；进一步研究给药系统的组成结构与其理化性能、靶向性、粘附性、生物毒性、门脉联控性及对结肠癌肝转移抑制作用的内在关系，揭示给药系统的门脉联控化疗机制，构建动物模型，建立对结肠癌肝转移有明显抑制作用的结肠靶向给药系统。该研究成果有利于提高我国结肠靶向给药系统的基础研究水平，为结肠癌肝转移的治疗提供新途径和思路。

结肠癌肝转移是治疗结肠癌过程中存在的关键问题之一。结肠靶向给药系统是解决问题的一种有效手段。然而，传统的结肠靶向给药系统存在载药量不足、靶向性较差、无法控制药物释放速率、易受环境影响、稳定性较差等缺点，故开发新型长效靶向给药系统成为该领域的研究热点。因此，本论文以新一代纳米材料氧化石墨烯为基体，分别采用海藻酸钠和羧甲基纤维素接枝得到海藻酸钠接枝氧化石墨烯、羧甲基纤维素接枝氧化石墨烯两种载体，然后分别负载了抗肿瘤药物5-氟尿嘧啶(5-FU)、甲胺蝶呤 (MTX)构建了基于天然聚合物接枝氧化石墨烯结肠控释给药系统，表征其组成结构，研究其释药性能、毒性和抗肿瘤活性。.1、采用改进的Hummers氧化法合成了晶面距约0.866 nm的少层氧化石墨烯，然后接枝海藻酸钠得到了海藻酸钠接枝氧化石墨烯载体(ALG-GO)，最后通过负载5-FU构建了负载5-FU的海藻酸钠接枝氧化石墨烯载体结肠控释给药系统5 FU/ALG GO。.2、以ALG-GO为载体，构建了负载MTX的海藻酸钠接枝氧化石墨烯载体结肠控释给药系统MTX/ALG GO。MTX在ALG-GO上的载药效果良好，特别是产率较高，适合大批量制备；其体外和体内释放实验表现出良好的缓释性和pH敏感性，可以通过灌胃给药有效地运送药物到结肠，实现了长效控释效果。.3、以羧甲基纤维素接枝氧化石墨烯(CMC-GO)为载体，将MTX负载上去构建了负载MTX的羧甲基纤维素接枝氧化石墨烯结肠控释给药系统MTX/CMC GO。MTX在CMC-GO上的载药效果良好，由于产率较高而适合大批量制备；其体外和体内释放实验均表现出良好的缓释性和pH敏感性，实现了长效控释效果。.4、对两种载体和三种结肠控释给药系统5-FU/ALG-GO、MTX/ALG-GO和MTX/CMC GO的毒性进行了评价，并研究了三种给药系统的抗肿瘤活性。研究结果表明：两种载体的细胞毒性都很小；三种给药系统的细胞毒性比原药更小或相近，且对小鼠主要器官的毒性均很小。三种结肠控释给药系统都具有显著的抗肿瘤活性，均可有效地抑制结肠癌肝转移。研究结果为三种结肠控释给药系统的临床应用提供科学依据，显示较广阔的应用前景。