PAMAM-COOH和PAMAM-PO3H2联合构建新型的牙本质基质蛋白-1仿生体系诱导胶原纤维内仿生矿化的机制探索

Human dentin is triggered in the organic collagen fibrils scaffold mediated by the regulation of biological molecular to form a unique shape, complex and orderly mineralized tissue，and the formation and development of dentin is a complex process of biomineralization .To restore normal morphology and function of the etched human hard tissue, it is crucial to focus on the biomineralization therapeutic method. Dentine matrix protein-1(DMP-1) plays important role in the process of modulating dentine biomineralisation with stabilising ACPs. The N terminal fragment of DMP-1 (rich of carboxyl) helps stabilize ACP into nanoparticles , and the phosphoserine-rich fraction of cleaved DMP-1 is thought to be responsible for apatite nucleation. Owing to their limited availability , high cost of production and instability，resort to DMP-1 biomimetic can be promising application. Based on the understanding of classical mineralization theory, in this study, PAMAM-COOH and PAMAM-PO3H2 are employed as biomimetic analogues to mimic the full role of N-terminal and C-terminal fragment of DMP-1, respectively；namely, DMP-1 biomimetic analogues were investigated to determine its potential for DMP-1 for intrafibrillar apatite assembly within a collagen matrix. In this study, the mechanism of intrafibrillar biomimetic mineralization was discussed, the methods and ways of improving intrafibrillar mineralization were explored, and new theoretical strategies could be provided for biomimetic mineralization of dentin.

人牙本质是以有机胶原纤维为支架，通过生物分子调控而形成形状独特、结构复杂有序的矿化组织，其发育形成是一个复杂的生物矿化过程。要使受损的牙本质恢复正常的形态和功能，促进胶原纤维内仿生矿化的方法和手段至关重要。牙本质基质蛋白-1（DMP-1）在牙本质生物矿化中起至关重要的调控作用，其N-端氨基酸片段(富含-COOH)起螯合稳定ACP作用、C-端氨基酸片段(富含-PO3H2)起成核结晶作用。然而，DMP-1获取困难且易变性，因此寻求DMP-1的仿生体具有重要的应用前景。基于对非经典矿化理论的认识, 本项目拟以PAMAM-COOH 和PAMAM-PO3H2联合构建新型的DMP-1仿生体系模拟DMP-1的N-端及C-端氨基酸片段的功能，研究其在胶原纤维内诱导磷灰石晶体成核生长的作用，探讨胶原纤维内仿生矿化的机制，探索提高胶原纤维内矿化的方法和手段，为牙本质的仿生矿化提供新的理论策略。

本研究通过使用牛I型胶原模拟人牙本质胶原纤维，并使用脱矿人牙本质模型，探索了PAMAM-PO3H2和 PAMAM-COOH协同诱导胶原纤维再矿化的作用，再矿化过程中发现发现（PAMAM-PO3H2）+（PAMAM-COOH）仿生体系有一定诱导胶原纤维仿生矿化效果，但所形成的矿化不够均一，尤其是胶原纤维内矿化不良。分析其原因为无定形磷酸钙稳定性不足，从而导致诱导形成的胶原纤维内矿化效果不佳。针对这一问题，我课题组探索合成了一种新的纳米复合生物材料PAMAM/n-HAP，能够有效地封闭牙本质小管，同时有较为理想的封闭深度，并且能够恢复其一定的硬度，有望作为一种新型的脱敏材料应用于临床应用，并可能成为口腔医学领域最具开发价值的新材料。