混合层裸露的牙本质胶原降解是粘接耐久性不佳和引起继发龋的重要原因。我们在已结题课题（NFSC 81500883）中发现EGCG生物改性可提高胶原强度和耐降解能力，但其保护作用的时效尚不明确；胶原纤维内矿化可发挥长期保护作用。体外研究多使用聚合物诱导的液态矿化前体（PILP）实现胶原纤维内矿化，口腔内缺乏不断补充的外源性聚合物，限制了临床实践应用。我们在前期工作中发现不需要形成PILP，聚乙烯亚胺（PEI）修饰胶原能利用溶液中的预晶核簇实现胶原原位仿生矿化且具有抗菌性，然而其具体作用和机制不明。由此，我们首次提出通过优化PEI修饰方案使牙本质胶原具备诱导原位矿化能力和抗菌性。本研究在建立PEI修饰胶原不同模型的基础上，探讨其对牙本质粘接性能、抗菌性及生物相容性的影响，阐明其实现原位仿生矿化和抗菌的作用和机制。研究成果将改善牙本质粘接耐久性和减少继发龋，减少粘接修复的失败率和医疗卫生支出。

The degradation of exposed dentin collagen in the hybrid layer is an important cause of poor bonding durability and secondary caries. In our previous project (NFSC 81500883), we found that the bio-modification of EGCG can improve the strength and anti-degradation ability of collagen. The protective effect of EGCG is still unclear, while the mineralization of collagen fibers can play a long-term protective role. Polymer-induced liquid precursors (PILP) are often used to achieve collagen intra-fibrillar mineralization in vitro. However, a lack of continuously supplemented exogenous polymers intra-orally limits its application in clinical scenarios. In our pilot study, we found that PILP is not necessary to achieve intra-fibrillar mineralization. Polyethyleneimine (PEI) modified collagen can biomimetically mineralize collagen in situ using prenucleation clusters (PNC) in solution and shows antimicrobial properties. However, its specific roles and mechanisms are not clear. Therefore, we proposed for the first time to optimize the PEI modification scheme to make dentin collagen possess the ability to induce in situ mineralization and antimicrobial activity. Based on different models of PEI-modified collagen, the effects of PEI-modified collagen on dentin bonding, antimicrobial activity and biocompatibility are investigated, and the mechanisms of biomimetic mineralization and antimicrobial activity are also elucidated. The results will improve dentin bonding durability, reduce the occurrence of secondary caries, contributing to lower the failure rate of bonding restorations and reduce medical expenditures.