构建具有抗菌、促矿化和釉质靶向的纳米复合材料并评价其在龋齿防治中的效果

Dental caries is one of the most common chronic diseases worldwide. Enamel, the outermost layer of the tooth, could be destroyed due to bacterial activities. A variety of chemotherapeutic agents have been tested that could kill bacteria with a high rate of success arresting existing caries and preventing new caries, but side effects have been reported, such as the surge of antimicrobial drug-resistant bacterial strains and staining of carious tissue black due to the oxidation of Ag+. Once the destruction of enamel occurs, it could scarcely be self-repaired. Unstructured non-enamel substitutes, such as amalgam, resin and ceramics, are widely used in the management of the enamel lesions. These artificial strategies have high failure rates for mismatch mechanical, physical and chemical property, meanwhile they are also invasive and high-cost..We will therefore develop a multi-functional nanopartical which could bind onto the enamel for anti-bacterial purpose and inducing self-repair of the enamel defect. First, a multi-functional nanopartical will be prepared by modifing polydopamine nanospheres (efficiently induce re-mineralization of the enamel under physiological conditions) with silver nanoparticles (efficiently inhibit bacterial adhesion onto the enamel and kill bacteria) and Alendronate (efficiently target enamel for raising bioavailability and reducing distribution in other organs). Then, the effect of the nanopartical to target-enamel, anti-bacterial function, and induce-remineralization would be evaluated, and then would be optimized bychanging the reaction conditions. The colour and the stability of such material would also be optimized. Because such material could target enamel to kill bacteria and induce remineralization, it could efficiently achieve to prevent and to cure dental caries simultaneously with high success rate, low toxicity, and low cost.

项目针对龋齿预防中抗菌药物导致的细菌耐药性、含银防龋涂料中Ag+氧化变黑和龋齿治疗中牙体组织磨除导致的结构损伤、异质填充材料力学机械性能不匹配导致的高的远期失败率，提出龋齿预防和无损治疗的新策略。本策略首先制备聚多巴胺球（诱导矿化、重建类釉质结构），在球表面原位还原Ag+获得纳米银颗粒（广谱抗菌且无变黑问题）、共价结合阿仑膦酸（靶向结合釉质、避免损伤其他器官），获得具有靶向釉质、良好抗菌性、诱导矿化的纳米复合材料，然后通过该材料在釉质表面形成具有抗菌、诱导矿化的多功能层，防止龋齿发生、且可以摄取唾液中的钙磷离子在釉质表面再生出类釉质结构（保护和修复釉质）。拟通过体外试验评价该材料的抗菌、诱导矿化、靶向釉质能力及其修饰后釉质表面的抑菌、类釉质结构再生能力和与牙体颜色的适配性；通过模拟体内环境，评价该策略在龋齿防治中的效果。本课题为龋齿预防和无损治疗、尤其对釉质再生研究提供了新的思路和技术体系

项目针对龋齿预防中抗菌药物导致的细菌耐药性、含银防龋涂料中Ag+氧化变黑和龋齿治疗中牙体组织磨除导致的结构损伤、异质填充材料力学机械性能不匹配导致的高的远期失败率，提出龋齿预防和无损治疗的新策略。本项目通过合成多巴胺纳米球并在球表面原位还原纳米银且共价连接阿仑膦酸，获得具有靶向釉质、良好抗菌性、诱导矿化的纳米复合材料，再利用该材料靶向牙体表面形成具有抗菌、诱导矿化的多功能层，防止龋齿发生、且可以摄取唾液中的钙磷离子在牙体表面形成矿化层（保护和修复釉质）。通过SEM、TEM和粒径测量优化制备工艺为采用1）2mg/mL的多巴胺聚合2h、2）浸泡pH10的1mg/mL的硝酸银溶液、3）戊二醛连接阿仑膦酸，最终制备出粒径300nm的球形复合材料，该材料具有广谱抑菌能力且能促进矿化，其可以靶向牙体并赋予牙体表面抗菌能力，浸泡模拟体液2周，表面完全矿化，有效抑制细菌导致的龋齿且可以修复牙体，纳米复合材料虽然导致牙体颜色变深但未导致牙体变黑。本课题为龋齿预防和无损治疗、尤其对牙体硬组织再生研究提供了新的思路和技术体系.为了更好了解多巴胺原位还原纳米银的工艺参数与其生物学性能的关系，我们在纯钛表面沉积多巴胺后浸泡硝酸银溶液，研究显示随着pH增加和硝酸银浓度增加，多巴胺表面结合的纳米银数量增加，且pH影响更大，尤其碱性环境更容易还原纳米银，纳米银表面表现出良好的抗菌能力，但也表现出细胞毒性，我们调整硝酸银的浓度（从10mg/mL-0.01mg/mL），随着浓度降低，细胞毒性下降，但并未消失，但在模拟体液或矿化液中浸泡会导致表面矿化层形成，以此改善材料表面细胞相容性。该结果间接说明纳米银随着矿化进行而毒性下降，但最好寻找低细胞毒性的抗菌试剂以替代银.氯己定作为常用伤口消毒成分，具有高效、广谱的抗菌性能，本课题利用硅烷偶联剂将氯己定接枝在纯钛表面，结果表明氯己定修饰表面具有良好的抑菌、杀菌能力，且不引起细胞毒性，其可以作为龋齿防治用纳米复合材料中的抗菌成分，避免银的副作用。