双驱动促矿化智能纳米粒子的构建及其在粘接中的机制研究

Postoperative dentine hypersensitivity caused by insufficient occlusion of dentinal tubule and poor durability are the two main clinical problems in dentin bonding. In previous studies, to solve the first problem, sealing materials were simply applied to seal dentinal tubules before bonding. However, the negative effect of pressure from dental pulp cavity was rarely considered, which is the main cause resulting in sealing material difficult to penetrate dentinal tubule. Moreover, in order to improve durability of adhesive, MMPs inhibitors were simply mixed to bonding agent. Its release was difficult to control and the effect was temporary. Additionally, bioactivity of materials has received little attention. It has been reported that dentinal tubule is rich in amino glycan and negative charge. Based on this, intelligent silica nanoparticles (SiNs) will be designed in our study. As the core, SiNs are combinded with a receptor targeting amino glycan and PEI targeting negative charge, which will drive SiNs into dentin tubule. Then, bioactive peptide-like LLP2A and MMPs inhibitor will be conjugated to SiNs by using a peptide substrate, CPLGLAGG, as linker, which can be specifically cleaved by MMP-2. When SiNs were attacked by MMP2 from tubular fluid and dentine, the peptide substrate is cut off, the inhibitor is released to inhibit MMPs activity, and LLP2A is released to recruit DPSCs and promote them to differentiate into odontoblasts to produce reparative dentin. In all, this study will provide a package of new strategies that address the two major clinical problems.

牙本质粘接主要存在着术后敏感和粘接耐久性不足的临床难题。在以往的研究中，为解决术后敏感，一般只是在粘接之前单纯的涂抹堵管材料，很少考虑到牙髓腔由内向外压力的负性作用，而此种压力是导致堵管物质难以渗入小管的重要原因之一；为提高粘接耐久性，一般只是简单地将MMPs抑制剂混合到粘接剂内，抑制剂的释放难以控制，效果较短暂; 同时粘接材料诱导修复性牙本质形成的能力很少受到关注。本课题将依据牙本质小管富含氨基聚糖和负电荷的性质，以硅纳米粒子为核心，利用氨基聚糖的受体结构和带有正电荷的PEI实现双驱动，使硅纳米粒子能够较易渗入牙本质小管；同时通过化学修饰，让纳米粒子可智能地释放具有生物活性的LLP2A多肽类似物和MMPs抑制剂。这种智能粒子既能更好地封闭牙本质小管，又能在MMPs激活时智能释放，促进修复性牙本质形成，同时减少胶原降解，为一揽子解决牙本质粘接中的两大临床难题提供新的策略和理论基础。

项目背景：牙本质粘接主要存在着术后敏感和粘接耐久性不足的临床难题。在以往的研究中，为解决术后敏感，只是在粘接之前单纯的涂抹堵管材料，很少考虑到牙髓腔由内向外压力的负性作用，而此种压力是导致堵管物质难以渗入小管的重要原因之一；为提高粘接耐久性，只是简单地将MMPs抑制剂混合到粘接剂内，抑制剂的释放难以控制，效果较短暂; 同时很少关注粘接材料的生物活性。.主要研究内容:第一部分：（1）带负电荷的MSN的合成；（2）智能纳米粒子的体外牙本质小管封闭效果、对牙本质渗透率的影响；（3）智能纳米粒子对粘接修复剪切强度的影响。第二部分：（1）基于介孔硅构建洗必泰缓释体系，进而改性牙科粘接系统；（2）智能材料控释药物能力、预防继发龋形成、提高粘接耐久性检测及机制研究。第三部分：（1）YAP调控成牙骨质细胞矿化能力的机制研究；（2）SIRT6调控成牙骨质细胞矿化能力的机制研究。.重要结果和关键数据：本课题组合成了带电荷的介孔硅纳米粒子，利用电泳沉积技术封闭敏感牙本质模型，用牙本质渗透性检测和扫描电镜证实了可靠的封闭效果，并发现该处理不影响牙本质粘接剪切强度。此外，还基于扩孔介孔硅纳米粒子建立了洗必泰缓释体系，利用其改进牙科粘接剂；经其改性的粘接剂具有药物缓释性能，能够有效抑制变异链球菌生物膜的生长，提高老化后的粘接强度。并且，我们还深入研究了牙骨质再生的分子机制，发现YAP部分通过抑制NF-κB通路促进炎症条件下的成牙骨质细胞系矿化，SIRT6通过抑制GLUT1的表达抑制成牙骨质细胞系的矿化。.科学意义：本研究成功合成了带电荷的介孔硅纳米粒子，首次使用电泳沉积技术封闭牙本质小管，在牙本质敏感的研究中具有广阔应用价值；本研究构建了基于介孔硅洗必泰缓释体系，改性牙科粘接系统；本研究揭示的成牙骨质细胞矿化机制对于控制牙周炎症、促进牙骨质再生丰富了理论基础，并为用生物手段治疗根部牙本质敏感及促进牙体粘接作用了提供了理论依据。

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