基于功能化介孔二氧化硅泡沫装载蛋白类大分子药物口服纳米给药系统的构建及评价

Peroral delivery of peptide/protein drugs is generally regarded as one of the elusive tasks facing the pharmaceutical technology, and the major barriers to effective oral delivery of these molecules include the following: 1) Poor intrinsic permeability across the intestinal epithelium; 2) Rapid enzymatic degradation in the gastro- intestinal tract and 3) Difficult diffusion trapped by the mucus. In this study, a novel mucus-penetrating nanoparticles based on mesocellular silica foam (MCF) was introduced to be as the carrier of the proteins, to improve their oral bioavailability. Firstly, a model protein recombinant human growth hormone (rGH) and four cell penetrating peptides (CPPs) were conjugated by the crosslinking agent to enhance its ability across the mucosa; Sencondly, MCF nanoparticles were prepared and the conjugates were loaded; Lastly, coating particles with a high density of PEG may reduce particle-mucus adhesion, resulting a shorter time and distance for drug transport. The study mainly focus on the stability of the drugs and the interactions between nanoparticles and drugs, to explain the effect of properties of nanoparticles (pore size, Mw or surface density of PEG) on the mucus-penetrating ability and drug delivery. The absorption enhancement effect of four CPPs are compared, and their mechanism will be discussed. This research can provide the basis for carrier material of biomacromolecules and promoting the development of oral protein delivery system.

当前生物大分子口服给药面临的生物屏障主要有肠道吸收屏障、酶屏障和粘液屏障。本课题主要针对以上三大屏障，首次构建了一种具有粘液穿透特性的新型蛋白-介孔二氧化硅泡沫（MCF）纳米给药系统，以期显著提高药物的口服生物利用度。首先，通过交联剂将重组人生长激素（rGH）与四种经典的细胞穿膜肽（CPPs）轭合，提高药物的跨膜吸收能力；然后，构建不同孔径的MCF纳米粒对上述轭合物进行负载；最后，将纳米粒表面进行PEG化修饰使其具有粘液穿透特性，大大缩短药物的吸收距离和时间，减少降解。本项目拟在对生长激素稳定化研究和载体与药物相互作用研究的基础上，揭示载体因素（不同孔径、PEG分子量和表面密度）与药物跨膜吸收及粘液穿透的关系，评价CPPs对rGH的吸收促进效率，阐明纳米粒的肠吸收机制，为无机材料装载大分子粘膜传递提供实验依据和理论参考。同时，对促进生物大分子传递系统的发展，将有重要的研究价值和实际意义。

本课题针对生长激素等多肽蛋白类药物的渗透性与稳定性差的缺点，设计制备了一种纳米药物载体，可以高效装载生长激素保证其稳定性，同时可以穿透肠道粘液，协助药物在肠粘膜上摄取与跨膜转运，实现生长激素的口服递送。首先制备具有合适粒径与电位，比表面积与孔道结构有所扩大的介孔硅纳米粒载体，完成生长激素的装载。同时，装载细胞穿膜肽作为吸收促进剂，进一步增强药物的细胞摄取、跨膜转运与体内吸收。在载体表面修饰聚乙二醇，使其具备良好的粘液穿透能力，缩短药物吸收距离，减少降解。用海藻酸钠对载体进行包被，实现肠道定点释放。本课题 对纳米药物载体进行了大量的体内外评价，采用i细胞模型研究了载体促进生长激素吸收的机制以及安全性，通过细胞模型和动物模型验证了制剂的有效性，显著提高了生长激素的口服吸收效果。