School of Chemistry, Physics and Mechanical Engineering, Science and Engineering Faculty, Queensland University of Technology, Brisbane, Australia.
Central Analytical Research Facility, Institute for Future Environments, Queensland University of Technology, Brisbane, Australia.
J Mech Behav Biomed Mater. 2019 Mar;91:416-424. doi: 10.1016/j.jmbbm.2018.10.020. Epub 2018 Oct 21.
In the biomedical arena, bacterial fouling is a precursor to complications such as implant infection and nosocomial infection. These complications are further compounded by biochemical mechanisms of resistance that threaten the action of traditional antibacterial strategies. Accordingly, antibacterial property by physical, not biochemical, mechanisms of action is becoming increasingly popular and promising. The present work falls in line with this paradigm shift. Here, microtextured Ti-6Al-4V surfaces were manufactured by destructive tension at three different cross-head speeds, probed with scanning electron microscopy (SEM) and multifocus optical microscopy, and treated with Staphylococcus aureus to study bacterial attachment. The fractographic study revealed the presence of dual-mode fracture, typical of Ti-6Al-4V, comprising regions of both ductile, microvoid coalescence and brittle, cleavage faceting. Based on load-extension curves, quantitative roughness data, and qualitative SEM visualisation, it was evident that cross-head speed modulated fracture behaviour such that increased speed produced more brittle fracture whilst lower speeds produced more ductile fracture. The topography associated with ductile fracture was found to possess notable antibiofouling property due to geometric constrains imposed by the coalesced microvoids. Accordingly, fracture at low cross-head speeds (1 mm/min and 10 mm/min) yielded significant reduction in bacterial attachment, whilst fracture at high cross-head speeds (100 mm/min) did not. The greatest reduction (~72%) was achieved at a cross-head speed of 1 mm/min. These findings suggest that antibiofouling property can be elicited by fracture and further 'tuned' by fracture speed. Discovery of this novel, albeit simple, avenue for topography-mediated antibacterial property calls for further research into alternate techniques for the manufacture of 'physical antibacterial surfaces'.
在生物医学领域，细菌污染是植入物感染和医院获得性感染等并发症的前兆。这些并发症进一步受到生化耐药机制的影响，这些机制威胁到传统抗菌策略的作用。因此，通过物理而不是生化作用机制的抗菌性能越来越受到关注和应用。本工作符合这一范式转变。在这里，通过破坏性拉伸在三种不同的十字头速度下制造了微纹理 Ti-6Al-4V 表面，并用扫描电子显微镜（SEM）和多焦点光学显微镜进行了探测，并与金黄色葡萄球菌一起处理以研究细菌附着。断口形貌研究表明存在双模式断裂，这是 Ti-6Al-4V 的典型特征，包括韧性微空洞聚合和脆性解理面两种断裂模式。基于载荷-延伸曲线、定量粗糙度数据和定性 SEM 可视化，很明显，十字头速度调制了断裂行为，即增加速度会产生更多的脆性断裂，而较低的速度会产生更多的韧性断裂。由于聚合微空洞施加的几何约束，与韧性断裂相关的形貌具有显著的抗生物污染特性。因此，在低十字头速度（1mm/min 和 10mm/min）下发生的断裂导致细菌附着显著减少，而在高十字头速度（100mm/min）下发生的断裂则没有。在十字头速度为 1mm/min 时，减少幅度最大（约 72%）。这些发现表明，抗菌性能可以通过断裂来诱发，并且可以通过断裂速度进一步“调整”。发现这种新颖的、尽管简单的、通过形貌介导的抗菌性能的方法，需要进一步研究替代技术来制造“物理抗菌表面”。
