Study of Finite Element Simulation on the Mechano-Bactericidal Mechanism of Hierarchical Nanostructure Arrays

Biomimetic nanostructures with bactericidal performancehave becomethe research focus in constructing sterilization surfaces, but themechano-bactericidal mechanism is still not fully understood, especiallyfor the hierarchical nanostructure arrays with different heights.Herein, the interaction between Escherichia coli cells and nanostructure arrays was simulated by finite element,and the initial rupture points, i.e., critical action sites, of bacterialcells and the effects of nanostructure geometries on the cell rupturespeed were analyzed based on the mechano-response of Escherichia coli cells on flat (identical heights)and hierarchical nanostructure arrays. The critical action sites ofbacterial cells on nanostructure arrays are all at the three-phasejunction zone of cell-liquid-nanostructure, but theyare slightly shifted by the height difference & UDelta;H of nanostructures on hierarchical nanopillar (NP)/nanosheet (NS)arrays, where the NP is higher than the NS. When & UDelta;H < 20 nm, the site nears the NS corners, and when & UDelta;H & GE; 20 nm, the site is consistent with that of theNP/NP array, i.e., the site locates at the three-phase junction zoneof cell-liquid-high NP. In addition, except for decreasingthe NP diameter, the NS thickness/width, or properly increasing thenanostructure spacing, the cell rupture can be accelerated via increasingthe & UDelta;H of nanostructures. & UDelta;H = 40 nm is distinguished as the boundary for the effect of nanostructure & UDelta;H on the cell rupture speed. When & UDelta;H < 40 nm, the cell rupture speed rapidly increases asthe & UDelta;H increases; when & UDelta;H & GE; 40 nm, the cell rupture speed reaches the maximum valueand remains stable. This study provides a new strategy on how to designhigh-efficiency bactericidal surfaces.