Synergistic anti-fouling coating and minimal systemic antibiotic injections for combating periprosthetic infections

项目摘要/摘要 假体周围感染(PPI)发生在1-4%的初次全关节置换和高达30%的翻修手术中 由于细菌，特别是葡萄球菌的倾向，关节置换术很难预防或治疗 金黄色葡萄球菌(S.aureus)，在种植体表面定植并形成生物膜，侵袭周围骨骼 矩阵。传统的抗生素预防和治疗不足以应对这一挑战。我们 最近显示，从Ti6Al4V髓内植入物(IM)接枝的防污损两性聚合物，当 联合单次全身注射万古霉素，有效抑制金黄色葡萄球菌在种植体上的定植 在小鼠股骨管的表面和PPI，显著优于单独治疗。在这里，我们的目标是 通过设计一种强大的抗PPI策略，促进这一前景看好的协同抗PPI策略的临床翻译 污垢嵌段共聚浸渍涂层作为一种现成的金属植入物产品，是一种有效和安全的 协同抗生素预防方案在一期种植体植入和种植期间的持续保护 分别对甲氧西林敏感和耐甲氧西林(MRSA)金黄色葡萄球菌PPI进行修订。在目标1中， 含防污两性离子侧链和金属的高相对分子质量聚甲基丙烯酸酯嵌段共聚物 通过顺序反加成碎裂链转移(RAFT)制备了表面结合侧链 聚合和铜催化的叠氮烯基环加成反应(CuAAC)。利用优秀的 RAFT聚合度的控制和侧链的高保真CuAAC改性 金属合金表面结合残留物的嵌段长度、化学性质和空间密度分别为 模数改变，以确定最佳的共聚物组成和浸涂方案，以实现一致 以及Ti6Al4V上稳定的防污涂层，可持续流动清洗、杀菌和货架储存。 涂层表面用水接触角、x射线光电子能谱和电阻来表征。 对非特异性蛋白质的吸附和细菌的体外定植。在AIMS 2和AIMS 3中，最高的防污浸泡- 将AIM 1中选择的涂层应用于Ti6Al4V IM销并与协同抗生素一起进行检测 预防，用于实现长期抑制PPI和由以下原因引起的复发PPI的有效性和安全性 甲氧西林敏感的金黄色葡萄球菌或耐甲氧西林金黄色葡萄球菌在大鼠体内植入初次和翻修植入物后， 分别进行了分析。PPI或复发PPI的程度作为针涂覆和时间/频率的函数 通过全血细胞计数和微CT定量纵向监测协同抗生素预防 皮质骨增厚，并通过终点定量取回的钉上的细菌，扭转试验和 6个月过程中移植股骨的组织学/电子显微镜特征。长期的 涂层的安全性通过股骨组织学和全身器官病理学在未感染的患者中进行检查 控制力。这项研究的成功将确定一种最佳的浸渍涂层成分和协同抗生素 预防方案，以有效地分别对抗PPI和复发PPI，从而建立其 临床相关性作为一种新的抗PPI策略，并将其推进到其临床翻译的下一阶段。

PROJECT SUMMARY/ABSTRACT Periprosthetic infections (PPIs) occur in 1-4% of primary total joint replacement and up to 30% of revision arthroplasty and are difficult to prevent or treat due to the tendency of bacteria, especially Staphylococcus aureus (S. aureus), to colonize and form biofilms on implant surfaces and to invade the surrounding bone matrices. Conventional antibiotic prophylaxis and treatments do not adequately address this challenge. We recently showed that anti-fouling zwitterionic polymers grafted from Ti6Al4V intramedullary (IM) implants, when combined with a single systemic injection of vancomycin, effectively inhibited S. aureus colonization on implant surfaces and PPI in murine femoral canals, significantly outperforming either treatment alone. Here, we aim to facilitate the clinical translation of this promising synergistic anti-PPI strategy by engineering a robust anti- fouling block copolymer dip-coating as an off-the-shelf product for metallic implants, and an effective and safe synergistic antibiotic prophylaxis regimen for sustained protection during primary implant insertion and implant revision, respectively, against methicillin-sensitive and methicillin-resistant (MRSA) S. aureus PPIs. In Aim 1, high-molecular weight polymethacrylate block copolymers with anti-fouling zwitterionic sidechains and metal surface-binding sidechains are prepared by sequential Reverse Addition Fragmentation Chain Transfer (RAFT) polymerization and copper-catalyzed azide-alkyne cycloaddition (CuAAC). Taking advantage of the excellent control over the degree of polymerization by RAFT and the high-fidelity CuAAC modification of sidechains, the respective block lengths and chemical nature and spatial density of metal alloy surface-binding residues are modularly altered to identify an optimal copolymer composition and dip-coating protocol to achieve consistent and stable anti-fouling coating on Ti6Al4V that can sustain flow wash, sterilization and over-the-shelf storage. Coated surfaces are characterized by water contact angels, x-ray photoelectron spectroscopy, and resistance to non-specific protein adsorption and bacterial colonizations in vitro. In Aims 2 and 3, the top anti-fouling dip- coating chosen in Aim 1 is applied to Ti6Al4V IM pins and examined, along with synergistic antibiotic prophylaxis, for the efficacy and safety in achieving long-term inhibition of PPI and recurrent PPI caused by methicillin-sensitive S. aureus or MRSA following the insertion of primary and revision implants in rats, respectively. The degree of PPI or recurrent PPI as a function of pin coating and the timing/frequency of synergistic antibiotic prophylaxis are longitudinally monitored by complete blood counts and µCT quantification of cortical bone thickening, and by endpoint quantification of bacteria on the retrieved pin, torsion test and histology/electron microscopy characterizations of explanted femurs over the course of 6 months. Long-term safety of the coating is examined by both femoral histology and systemic organ pathology in the uninfected control. Success of this study will identify an optimal dip-coating composition and synergistic antibiotic prophylaxis regimens to effectively combat PPI and recurring PPI, respectively, thereby establishing their clinical relevance as a new anti-PPI strategy and advancing them to the next stage of their clinical translations.