携蜂毒肽的控制释放靶向纳米给药系统

Melittin is a natural biotoxin peptide which derived from the venom of the honeybee Apis mellifera. It has been widely reported that melittin can induce apoptosis in various tumor cells. However, the in vivo application of this peptide for cancer therapeutics is hampered by lytic toxicity and degradation. In this project, we will develop a specific strategy to synthesize a nanoscale delivery vehicle for melittin, in which melittin is loading in mesoporous silica nanoparticles (MSN) and protected by redox-responsive molecular caps at the MSN surface. This designed delivery vehicle is expected to preserve the anticancer activity of melittin by the MSN structure before vehicle uptaked into the targeted tumor cells, and stimulate the intracellular release of the cytolytic peptide by the cleave of disulfide resulted from the high concentration of glutathione in the intracellular matrix of tumor cells. Firstly, the effect of MSN pore properties on the melittin conformation, the uptake and release profiles of melittin by the MSN, and the biological activity of melittin after released from MSN will be investigated. In the synthesis process of vehicle, after redox-responsive disulfide be grafted at the MSN surface, PEG and folate functionalized will be employed to enhanced biocompatibility and cancer cell specific, and then cyclodextrins will be assembly with PEG to encapsulate melittin within the porous channels of MSN. To confirm the potential of vehicle for targeted melittin delivery, the in vitro controlled-release behavior of melittin and the intracellular delivery in three different cell lines will be investigated. Furthermore, tumor suppression of the delivery vehicle will be study on HepG2 xenograft tumor model to demonstrate the cancer therapy profiling in vivo. This project develop an innovative nanovehicle which combine the biocompatibility and high payloads of MSN, with wide-spectrum, high efficient, and less side effects anticancer properties of melittin. It represents a general delivery vehicle for natural biotoxins to exploit anticancer applications.

课题围绕天然生物毒素蜂毒肽作为抗癌药物存在的溶血副作用以及在血清中易被降解、抑制等关键难题，以介孔氧化硅纳米颗粒作为给药载体，通过对蜂毒肽在介孔孔道中的负载行为研究，阐明蜂毒肽在孔道中的构像、生物活性等与载体孔道性质的关系，进而优化介孔氧化硅的刚性孔道结构对蜂毒肽的保护作用，以消除蜂毒肽的副作用和不稳定性；并进一步构筑对氧化还原响应的蜂毒肽控制释放靶向纳米药物，对其胞内胞外的控制释放行为，活体动物中控制释放的抗癌药效等进行系统研究，建立蜂毒肽在肿瘤治疗中应用的新方法。本课题综合介孔氧化硅生物相容性好，药物负载量大，易于表面修饰的特点以及蜂毒肽广谱快速的癌细胞杀伤功能，有望解决蜂毒肽应用于肿瘤治疗的传统难题，开发出广谱、高效、低副作用的新型癌症治疗纳米药物，为天然生物毒素的抗癌靶向给药提供新的通用思路，推进抗癌纳米药物的发展。

蜂毒肽是一种典型的抗菌肽，其细胞膜致孔特性使其成为潜在的抗癌药物，但蜂毒肽的溶血副作用，以及在血清中易被降解的不稳定性限制了其在癌症治疗中的应用。本项目以介孔氧化硅作为给药载体，借助介孔孔道对蜂毒肽的保护作用降低其副作用与不稳定性，在此基础上利用控制释放和靶向修饰进一步提高给药效率。项目研究了蜂毒肽在不同孔径，不同孔道内表面修饰条件下的负载作用，结果显示大孔径以及内孔道的羧酸基团修饰可以有效提高蜂毒肽在介孔氧化硅中的负载效率；通过蜂毒肽的溶血活性实验发现传统的共价交联试剂对蜂毒肽的生物活性有显著的抑制作用，为解决此难题，项目组采用聚乙二醇与环糊精自组装包覆，较好的保留了负载之后蜂毒肽的生物活性；借助二硫键的氧化还原控制释放以及叶酸靶向修饰，建立的给药系统降低了蜂毒肽传递过程中的提前释放，细胞毒性实验进一步证实了新的给药系统对癌细胞的杀伤作用。本项目的研究揭示了蜂毒肽在介孔孔道中的负载行为，证实介孔孔道的保护有助于降低蜂毒肽的副作用与不稳定性，而自组装的包覆方法则为多肽类药物给药系统的建立提供了新的思路。