程序化多功能结肠癌口服药物投递载体的构建及性能研究

Theranostic agents developed based on 'all-in-one approach' will show great promise in the treatment of colon cancer, because they allow detection as well as monitoring of colon cancer at an early stage, and delivering anticancer agents over an extended period for enhanced therapeutic efficacy with low toxicity. With the help of nanoplatform technology, we will develop a series of novel smart hybrid nanomaterials that not only carry and deliver chemotherapeutics but also provide real-time imaging of drug delivery and distribution in vivo. We will systhsize poly(L-glutamic acid) dendrimers and conjugate the denerimers onto hyaluromic acid. Right before the loading of MR imaging probes-MnO nanoparticles, the poly(L-glutamic acid) dendrimers will be conjugated with doxorubicin via pH-sensitive hydrazine bonds. Once taken up by both cancer cells and cancer stem cells through CD44 receptor, the conjugated membrane fusion peptide on the nanofomula should breach membranes for fast cytosolic and nuclear delivery of doxorubicin. Subsequent layer-by-layer(LBL) self-assembly is then utilized to fabricate the enteric resin/chitosan nanospheres with time delay, pH sensing and enzyme response function for oral colon delivery. We seek to determine and delineate the sophisticated multifunctional theranostic agents with optimized properties for a range of related applications: oral colonic drug delivery, MRI visualization, cancer stem cell targeted and triggered delivery of chemotherapeutics for therapy. If successful, the proof-of-concept will allow for preclinical and clinical applications of theranostics in colon cancer therapies.

设计和构建具有肿瘤诊断和治疗功能的靶向智能型药物传输系统是实现结肠癌早期诊断及低毒高效化疗的重要措施。本项目拟通过对高分子载体的材料设计，实现对药物载体功能和性质的调控：1）基于层层自组装技术构建肠溶树脂/壳聚糖纳米微球外壳，赋予时滞型、PH敏感兼具结肠微生物酶响应功能，通过壳层的精确调控实现结肠高效定位投递功能；2）透明质酸接支谷氨酸树状大分子，阿霉素作为疏水部分通过与树状大分子的亲水基团以腙键共价结合，制备高载药量的集成载药系统并负载疏水高灵敏MnO形成纳米微球内核，实现CD44+结肠癌干细胞的靶向给药及MRI分子显像诊断功能；3）纳米复合物进入胞内体中，膜融合肽使复合物突破胞内体的包膜，阿霉素快速移送至细胞核发挥抗结肠癌效应。本项目实施可望获得一类具有我国自主知识产权、潜在临床价值的MR可视化、口服结肠定位、结肠癌干细胞靶向、癌细胞内环境响应及细胞核高效递送的多功能集成载药系统。

本课题设计并制备了一系列新型的肿瘤靶向可视化药物递送载体，优化了纳米载药系统的理化性能并进行了体内外生物学功能评价。在研究工作中，成功实现了无创影像可视化、靶器官/细胞定位、癌细胞内环境响应及细胞核高效递送的多功能载药系统的可控制备。拓展并设计构建了基于磁纳米颗粒，上转换纳米材料，铁蛋白纳米笼的肿瘤微环境响应的药物载体将活性药物靶向运送到特定的细胞或组织里并实现多模态影像系统可视化监控,如在肿瘤组织高表达组织蛋白酶的作用下，纳米结构表面的功能性多肽被选择性切断，暴露出的氨基酸残基和相邻粒子表面特异的识别分子发生共价交联反应，从而促进了该纳米结构在肿瘤部位有效的选择性富集。运用仿生合成方法制备了硫化铜-铁蛋白纳米笼，其具有高灵敏的肿瘤特异性靶向效应，在放射性核素64Cu标记后可利用PET及光声两种成像模式进行肿瘤靶向分布成像；同时利用较低的激光照射便可达到高效的肿瘤光热治疗效果。实验中发现超顺磁氧化铁纳米颗粒能够选择性作用于多种癌细胞，通过靶向癌细胞线粒体电子传递链导致线粒体活性氧升高从而诱导癌细胞凋亡，对基于氧化铁纳米颗粒构建载药系统的生物医学应用和安全性评价方面具有重要意义。本课题负责人多次参加本领域专业学术会议并做邀请报告。通过本项目的实施，发表 SCI 收录论文19篇，参编Elsevier等出版社发行的英文专著4部，申请中国发明专利4项。上述研究为我们在后续课题开展更加深入系统的肿瘤靶向诊疗一体化探针研究奠定了坚实的基础。