Bactericidal effect derived from nanostructured surface was evaluated in the point of view of the motility of E. coli. The results suggest that the properties strongly depend on bacterial motility.

The adhesion behavior and bactericidal properties of the nanostructured surface of Si nanopillar array, which mimicked a cicada wing surface, were evaluated using Escherichia coli. Wettability of the nanostructured surface was controlled by using self-assembled monolayer (SAM). The adhesion behavior was strongly dependent on the wettability of the surface and whether it was a nanostructured or a flat surface. The number of adhered cells on the nanostructured surface was higher than that on the flat Au surface. In addition, the cell membrane was more strongly damaged at a higher contact angle than at a lower contact angle on the nanostructured surface. Time-lapse imaging was used to analyze the changes in fluorescence intensity caused by the effusion of an intercellular fluid, including fluorescent protein (mCherry), at the single cell level on the cicada wing surface and the artificial nanostructured surface. We found that there were three stages of changes in the fluorescence intensity gradient.

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We focused on a cicada wing which has superhydrophobic surface, antireflection to the light, unique tribology, and antibacterial property. From the SEM view, circular truncated cones in nanoscale were widely spread with regularly. It was just like nanopillar array. After the signature pattern was analyzed, we mimicked its structure composed of Si. Si nanostructure was fabricated mainly by wet process to decrease the cost but its dimension was controllable. We reported antibacterial property of the structure. Fabricated Si nanopillar array showed antibacterial property to E. Coli.

Graphene oxide (GO) was reduced by either a thermal treatment in Ar ambient or a chemical process using hydrazine monohydrate. A Ge surface loaded with reduced GO (RGO) was immersed in water containing dissolved O 2 molecules. We demonstrated that etch pits were formed by the immersion, whose shape depended on the initial form (particles or dispersed sheets) of RGO on Ge. We speculate that a Ge surface in contact with RGO is selectively etched in water by the catalytic activity of RGO, which enhances the oxygen reduction reaction.