Peptide-PAMAM-galardin系统的构建及其诱导I型胶原仿生再矿化的分子机制研究

Type I collagen matrix is the fundamental scaffold for the growth of dentin minerals, hence, how to protect collagen fibrils from invading of MMPs in the oral microenvironment and maintain the integrity of collagen structure become the urgent key problem for the clinical application of biomimetic remineralization. Our previous studies have demonstrated the excellent capability of PAMAM to induce biomimetic remineralization, based on this, endowing PAMAM with the function of protecting collagen structure has a great clinical significance. This project aims to develop a novel multifunctional Peptide-PAMAM-galardin system via symmetrically combining several peptides, which is from the non-collagen proteins and can specifically bind to collagen fibrils, to the external functional groups of PAMAM, and loading galardin that functions as MMPs inhibitor with the internal cavity of PAMAM. In the microenvironment with MMPs, this system will strongly bind to several collagen molecules through the peptides to promote the cross-linking of collagen fibrils, and release galardin to constantly inhibit MMPs at the same time. The system will also achieve biomimetic remineralization of type I collagen fibrils through absorbing Ca and P ions via the external carboxyl groups on PAMAM. At last, the project will explore the action mechanism between the system, collagen molecules and Ca and P ions through molecular simulation. This project is very promising to provide novel strategy and technology for the development of the biomimetic remineralization anti-caries biomaterials.

I型胶原基质是牙本质矿物生长的基础支架，因此，如何在口腔微环境中保护胶原免受MMPs侵袭、维持胶原结构完整是仿生再矿化临床应用亟待解决的关键问题。课题组前期研究证明了PAMAM优异的仿生再矿化作用，在此基础上，赋予PAMAM胶原保护功能具有重要的临床意义。本课题拟通过在PAMAM表面对称性接枝多条非胶原蛋白中特异性结合胶原的peptide片段，并利用PAMAM内部空腔装载MMPs抑制剂galardin,构建Peptide-PAMAM-galardin系统。在MMPs环境中，该系统可通过peptide特异性结合多个胶原分子，促进胶原交联，同时缓释galardin，持续抑制MMPs活性，并利用PAMAM表面羧基基团吸附钙磷沉积于胶原支架，诱导胶原仿生再矿化。最后，借助分子模拟模型，从分子水平诠释该系统与胶原分子和钙磷离子的相互作用机制。本课题将为矿化防龋材料的研发和临床应用提供新思路和新技术。

龋病是人类口腔的常见病和多发病，导致牙体形态缺损和功能障碍，严重危害人类口腔及全身健康。近年来，利用仿生再矿化技术促进脱矿牙本质胶原再矿化，逆转龋坏进程，恢复牙本质结构、形态和功能，成为龋病防治的新方向。I型胶原基质是牙本质矿物生长的基础支架，因此，如何在口腔微环境中保护胶原免受胶原酶侵袭、维持胶原结构完整是仿生再矿化临床应用亟待解决的关键问题。课题组前期研究证明了树枝状大分子（PAMAM）优异的仿生再矿化作用，在此基础上，赋予PAMAM胶原保护功能具有重要的临床意义。.本课题通过文献回顾和胶原降解实验筛选出了一种非胶原蛋白来源的能够稳定胶原纤维的多肽序列（NGV），进而将其接枝到PAMAM外部基团，同时利用PAMAM内部空腔装载胶原酶抑制剂galardin，成功制备了装载有galardin的PAMAM-多肽复合体（PAMAM-NGV@Galardin）。在含有胶原酶的人工唾液中，PAMAM-NGV@Galardin展现出极佳的促胶原交联和抵御胶原酶酶解的能力，并有效诱导了脱矿牙本质的仿生再矿化。在大鼠龋病模型中，PAMAM-NGV@Galardin表现出良好的生物相容性，并有效抑制了牙本质龋的发生和发展。最后，通过分子模拟，我们初步阐明了PAMAM-NGV@Galardin促进胶原交联和释放药物的分子机制：一方面，PAMAM-NGV@Galardin通过NGV多肽在PAMAM表面的空间区域形成协同运动的小团簇和畴区，限制胶原链运动，促进胶原交联；另一方面，酸性环境中加拉定分子向溶液中的释放需要翻越的能垒较中性环境更高，反应速率更慢，因此酸性环境中药物的释放更持久。.本课题的研究成果将为矿化防龋材料的研发和临床应用提供新思路和新技术。