感染响应型人工关节表面构建及其作用机理研究

Infection is one of the serious complications after total joint arthroplasty (TJA). There still lack of effective prevention and treatment methods at present. This program is to construct an “infection-responding” artificial joint surface. A kind of peptide chain which is sensitive to some bacteria secreted proteases will be synthesized. The peptide chains will be fixed on the surface of the artificial joint with antibiotic moleculer grafted at one end. The selective enzymatic hydrolysis effects of the proteases which are secreted by bacterias around prosthesis on these peptide chains are utilized. The peptide bonds will be enzyme digested and then the drug will be released when infection occurs. Therefore, respondsive anti-infection function will achieve by this methord. The integrin specificity recognition sequence is also designed into this peptide chain to facilitate the integration between the implant and bone tissue. The low temperature plasma modification, solid-phase synthesis, activation and crosslinking methods will be utilized to construct the “infection-responding” surface. The influences of the surface modification process and conditions on the structure, physical and chemical properties and also the biocompatibility will be discussed. The function and mechanism of this infection responding surface on bacterial biofilm (BF) formation, drug release, as well as the osteoblasts beheviour and functions will be investigated in the BF model In Vitro. The interaction regulations among proteinase activities, drug concentration, infection levels and interface combination around the prosthesis will also be researched in joint replacement infection animal model. At last, the biological mechanism of this “infection-responding” surface will be clarified. If the project complete successfully, a highly efficient and site-specific new drug delivery method for preventing and treating the infection after TJA will be established.

感染是人工关节置换后的严重并发症之一，针对目前临床尚缺乏有效防治方法，本申请项目提出构建一种感染响应型人工关节表面。该表面的设计思路是合成一段细菌蛋白酶敏感型肽链，该肽链一端接抗生素，另一端固定在假体表面；利用感染发生时假体周围细菌释放的蛋白酶对该肽链的选择性酶解作用，酶切肽键释放抗生素，从而实现响应性抑制感染的目的；同时该肽链含整合素特异性识别序列，因此该表面兼具抗感染和促假体与骨界面整合的双重作用。采用低温等离子辐射、固相合成、活化交联等方法构建感染响应型表面；探讨修饰工艺对理化结构性能及生物相容性的影响；体外细菌生物膜（BF）模型中研究响应型表面对抑制BF形成、药物释放及成骨系细胞行为功能的作用机理；关节置换感染动物模型中研究假体周围蛋白酶活性、药物浓度、感染程度及界面整合间相互作用规律，最终阐明感染响应型表面的生物学作用机制。本项目如成功实施将为关节置换后感染的防治提供一种新途径。

感染是假体松动是人工关节置换术（TJA）后最为严重的并发症，目前还缺少有效预防及治疗TJA术后感染同时防止假体松动的方法。本课题针对现有方法的局限性，基于感染发生时组织微环境的变化，提出利用对细菌分泌的蛋白酶敏感及含RGD序列的肽链将抗生素固定在钛合金关节表面，利用细菌生物膜（BF）形成过程中金葡菌聚集释放的蛋白酶对该肽链的选择性酶解作用，达到通过感染的发生及程度控制调节抗生素释放及早期抑制假体表面BF生成的目的，同时实现促进假体与骨组织表面整合的目的。本研究按计划完成感染响应型钛合金表面的构建、表面理化结构性能表征及生物相容性评价、体外相关蛋白酶作用下药物释放规律研究、体外BF模型中对BF抑制、药物释放及成骨系细胞行为的作用机理及体内动物模型中验证了感染响应型钛表面对于感染的抑制效果。本研究还根据研究结果增加了自驱动带电抑菌促修复医用钛合金表面的构建及抑菌促成骨性能研究。此外，还研究了层层自组装生物矿化骨科植入物表面的构建及促成骨性能。总之，通过本研究的执行，成功构建出感染响应型抗生素释放钛基植入物表面，证明其具有细菌感染响应性药物释放的效果。体内外实验验证了该表面具有发生感染时响应性抑菌杀菌、响应性控制感染的作用，并证明该表面具有促进成骨的作用。此外，为了找到更简单的改性方案得以应用，我们利用摩擦纳米发电机（TENG）构建出带负电荷的植入物表面，研究表明其同样具有抑制BF形成，破坏成熟的BF以及促进成骨的作用。通过层层自组装及生物矿化不仅能在钛金属表面实现有效促成骨的作用，由于方法的普适性，还能够作用于其它材质植入物表面。本研究在生物响应智能性生物材料、药物载体方面具有一定的科学意义。经过本研究多种表面构建方法的探索，我们已经初步筛查出较为简单实用的抗感染促修复表面构建方式。我们将在之后的研究中，逐渐完善该技术，进而能够用于骨科长期植入物，尤其是人工关节表面改性的实际应用。