Theoretical and computational investigations into mechanobactericidal activity of nanostructures at the bacteria-biomaterial interface: a critical review

Abstract

Mechanobactericidal surfaces kill bacteria upon contact by posing landscapes hostile to them and have rapidly gained popularity amongst researchers over the past decade. But several fundamental aspects of the physical interactions between bacteria and nanostructures and the underlying killing mechanisms are still poorly understood. This is partly attributable to the difficulties associated with the characterization of the bacteria-nanostructure interface in a biological environment during the killing process and to the stochastic and non-linear behaviors generally associated with biological systems. However, several analytical and computational models have presented and analyzed possible killing routes and have proven useful in understanding different aspects of the phenomena. Analytical models formulate equations, often based on energy considerations, and aim to predict optimal nanostructure dimensions. They are more widely used than computational models that try to simulate the killing process and the stress or strain fields in the cell membrane through numerical methods. These models provide insights into the forces responsible for the spontaneous penetration of the cell into the nanostructures, which are still highly debated in the field. They have also helped to correlate the nanostructure dimensions with their bactericidal activity to optimize such values and facilitate the translation of this technology to physiological conditions. This review focuses on the rupture of the bacterial cell wall by nanopillars or similar high aspect ratio structures and applying these principles to the deformation of the cell membrane. Many recent interesting experimental results that either refute our current understanding or have the potential to challenge the current consensus are also discussed. Lastly, the limitations of the current strategies and opportunities to address the unresolved gaps in the field are also presented.