Senevirathne S W M A Ishantha, Toh Yi-Chin, Yarlagadda Prasad K D V
Centre for Biomedical Technologies, Queensland University of Technology, Brisbane, QLD 4000, Australia.
School of Mechanical, Medical, and Process Engineering, Faculty of Engineering, Queensland University of Technology, Brisbane 4000 QLD Australia.
ACS Omega. 2022 Jun 28;7(27):23201-23212. doi: 10.1021/acsomega.2c01208. eCollection 2022 Jul 12.
Nanotopographic surfaces are proven to be successful in killing bacterial cells upon contact. This non-chemical bactericidal property has paved an alternative way of fighting bacterial colonization and associated problems, especially the issue of bacteria evolving resistance against antibiotic and antiseptic agents. Recent advancements in nanotopographic bactericidal surfaces have made them suitable for many applications in medical and industrial sectors. The bactericidal effect of nanotopographic surfaces is classically studied under static conditions, but the actual potential applications do have fluid flow in them. In this study, we have studied how fluid flow can affect the adherence of bacterial cells on nanotopographic surfaces. Gram-positive and Gram-negative bacterial species were tested under varying fluid flow rates for their retention and viability after flow exposure. The total number of adherent cells for both species was reduced in the presence of flow, but there was no flowrate dependency. There was a significant reduction in the number of live cells remaining on nanotopographic surfaces with an increasing flowrate for both species. Conversely, we observed a flowrate-independent increase in the number of adherent dead cells. Our results indicated that the presence of flow differentially affected the adherent live and dead bacterial cells on nanotopographic surfaces. This could be because dead bacterial cells were physically pierced by the nano-features, whereas live cells adhered via physiochemical interactions with the surface. Therefore, fluid shear was insufficient to overcome adhesion forces between the surface and dead cells. Furthermore, hydrodynamic forces due to the flow can cause more planktonic and detached live cells to collide with nano-features on the surface, causing more cells to lyse. These results show that nanotopographic surfaces do not have self-cleaning ability as opposed to natural bactericidal nanotopographic surfaces, and nanotopographic surfaces tend to perform better under flow conditions. These findings are highly useful for developing and optimizing nanotopographic surfaces for medical and industrial applications.
纳米拓扑表面已被证明在接触时能够成功杀死细菌细胞。这种非化学杀菌特性为对抗细菌定植及相关问题开辟了一条替代途径，尤其是细菌对抗生素和防腐剂产生耐药性的问题。纳米拓扑杀菌表面的最新进展使其适用于医疗和工业领域的许多应用。纳米拓扑表面的杀菌效果通常是在静态条件下进行研究的，但实际的潜在应用中确实存在流体流动。在本研究中，我们研究了流体流动如何影响细菌细胞在纳米拓扑表面上的黏附。对革兰氏阳性和革兰氏阴性细菌物种在不同流体流速下进行测试，以观察流动暴露后它们的留存情况和活力。在有流动的情况下，两种细菌物种的黏附细胞总数均减少，但不存在流速依赖性。随着流速增加，纳米拓扑表面上存活细胞的数量显著减少，两种细菌物种均如此。相反，我们观察到黏附死细胞的数量呈流速无关的增加。我们的结果表明，流动的存在对纳米拓扑表面上黏附的活细菌细胞和死细菌细胞有不同的影响。这可能是因为死细菌细胞被纳米特征物理刺穿，而活细胞通过与表面的物理化学相互作用黏附。因此，流体剪切力不足以克服表面与死细胞之间的黏附力。此外，流动产生的流体动力可导致更多浮游和脱离的活细胞与表面的纳米特征碰撞，从而使更多细胞裂解。这些结果表明，与天然杀菌纳米拓扑表面不同，纳米拓扑表面不具有自清洁能力，并且纳米拓扑表面在流动条件下往往表现得更好。这些发现对于开发和优化用于医疗和工业应用的纳米拓扑表面非常有用。
