骨科植入体抗细菌生物被膜——抗炎双功能表面的构建及微电流环境下的功能研究

The construction of functional surfaces with antibacterial and osseointegration enhancement functions on an orthopedic implant is promising to effectively prevent the failure of the implant. However，the current design of the functional surfaces focuses on the planktonic bacteria and bone-forming cells, and the characteristics of biofilm and the influence of the microenvironment (especially the inflammation and microcurrent generated due to human daily activities) on osseointegration are not fully considered. Thus, the constructed functional surfaces usually exhibit weak resistance to biofilm formation, and their ability to promote osseointegration needs further improvement. In this project, we intend to co-immobilize deoxyribonuclease I (DNase I) and polycations on an implant surface through covalent bonding to construct a dual-functional surface that can prevent biofilm formation and regulate inflammation. The immobilized DNase I can prevent biofilm formation by breaking down extracellular polymeric substances secreted by the bacteria. At the same time, the polycation can not only avoid excessive activation of toll-like receptor signaling pathways of macrophages and regulate the degree of inflammatory responses, but also produce a synergistic antibacterial effect with the DNase I through its unique bactericidal property. In addition, an appropriate power supply scheme will be designed to simulate the real microcurrent environment of the human body for investigating the effect of the microcurrent environment on the interaction between the dual-functional surface and bacteria or cells. Therefore, this project will provide a theoretical and experimental basis for designing the next generation of functional surfaces on orthopedic implants.

在骨科植入体上构建具有抗菌、促骨整合功能的表面可以有效防止植入体的失效。但目前关于此类功能表面的设计，主要针对浮游态细菌与成骨细胞，没有充分考虑生物被膜的特点，以及植入体微环境特别是炎症反应与人体日常活动产生的微电流环境对功能表面骨整合的影响，因而大多数表面对生物被膜的抵抗能力较弱，促进骨整合的能力需进一步提高。在本项目中，我们拟将脱氧核糖核酸酶（DNase I）与聚阳离子共价固定在植入体表面，构建抗生物被膜——抗炎双功能表面。预期表面的DNase I可以通过分解细菌分泌的胞外聚合物来防止生物被膜的形成；同时聚阳离子不仅可以避免巨噬细胞过度激活Toll样受体通路，调控炎症反应程度，其特有的杀菌功能还能与DNase I产生协同抗菌作用。此外，还将设计合适的供电方案以模拟人体实际微电流环境，研究在微电流环境下功能表面与细菌、细胞的相互作用及规律，为骨植入体设计新型功能表面提供理论和实验基础。

在骨科植入体上构建具有抗菌、促骨整合功能的表面可以有效防止植入体的失效。但目前关于此类功能表面的设计，主要针对浮游态细菌与成骨细胞，没有充分考虑生物被膜的特点，以及植入体微环境特别是炎症反应与人体日常活动产生的微电流环境对功能表面骨整合的影响，因而大多数表面对生物被膜的抵抗能力较弱，促进骨整合的能力需进一步提高。在本项目中，我们将脱氧核糖核酸酶（DNase I）与聚阳离子共价固定在植入体表面，构建抗生物被膜——抗炎双功能表面。表面的DNase I可以通过分解细菌分泌的胞外聚合物来防止生物被膜的形成；同时聚阳离子不仅可以避免巨噬细胞过度激活Toll样受体通路，调控炎症反应程度，其特有的杀菌功能还能与DNase I产生协同抗菌作用。此外，我们还设计了合适的供电方案以模拟人体实际微电流环境，研究在微电流环境下功能表面与细菌、细胞的相互作用及规律，发现微电流能与表面固定的聚阳离子和DNase I联合作用，可以增强其抗菌抗炎性能，为骨植入体设计新型功能表面提供理论和实验基础。此外，本项目还针对非金属基的骨科材料，开发了表面处理技术，构建了抗菌——促骨整合双功能表面，有望提升颅骨修复材料的临床表现。为了进一步验证电流与功能表面对骨修复的作用，还将改性后的金属植入大鼠体内，发现电刺激与功能表面联用能够显著提升大鼠的骨再生。