Nanopatterned surfaces are believed to kill bacteria through physical deformation, a mechanism which has immense potential against biochemical resistance. Due to its elusive nature, this mechanism is mostly understood through biophysical modelling. Problematically, accurate descriptions of the contact mechanics and various boundary conditions involved in the bacteria-nanopattern interaction remain to be seen. This may underpin conflicting predictions, found throughout the literature, regarding two important aspects of the mechanism - that is, its critical action site and relationship with geometry. Herein, a robust computational analysis of bacteria-nanopattern interaction is performed using three-dimensional finite element modelling which incorporates relevant continuum mechanical properties, multilayered envelope structure and adhesion interaction conditions. The model is applied to more accurately study the elusory mechanism and its enhancement via nanopattern geometry. Additionally, micrographs of bacteria adhered on a nanopatterned cicada wing are examined to further inform and verify the major modelling predictions. Together, the results indicate that nanopatterned surfaces do not kill bacteria predominantly by rupture in between protruding pillars, as previously thought. Instead, non-developable deformation about pillar tips is more likely to create a critical site at the pillar apex, which delivers significant in-plane strains and may locally rupture and penetrate the cell. The computational analysis also demonstrates that envelope deformation is increased by adhesion to nanopatterns with smaller pillar radii and spacing. These results further progress understanding of the mechanism of nanopatterned surfaces and help guide their design for enhanced bactericidal efficiency.

中文翻译：

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纳米图案表面的细菌相互作用和死亡机制

纳米图案表面被认为可以通过物理变形杀死细菌，这种机制具有巨大的生化抗性潜力。由于其难以捉摸的性质，这种机制主要通过生物物理建模来理解。有问题的是，对细菌-纳米图案相互作用中涉及的接触力学和各种边界条件的准确描述仍有待观察。这可能支持在整个文献中发现的关于机制的两个重要方面的相互矛盾的预测 - 即其关键作用部位和与几何形状的关系。在此，使用结合相关连续介质力学特性的三维有限元建模对细菌-纳米模式相互作用进行了稳健的计算分析，多层信封结构和粘附相互作用条件。该模型用于更准确地研究难以捉摸的机制及其通过纳米图案几何形状的增强。此外，还检查了附着在纳米图案蝉翼上的细菌显微照片，以进一步了解和验证主要的建模预测。总之，结果表明纳米图案表面不会像以前认为的那样主要通过突出柱之间的破裂来杀死细菌。相反，支柱尖端的不可展开变形更有可能在支柱顶点处产生一个关键部位，这会产生显着的平面内应变，并可能局部破裂并穿透细胞。计算分析还表明，通过粘附到具有较小柱半径和间距的纳米图案，包络变形会增加。