The nature of inherent bactericidal activity: insights from the nanotopology of three species of dragonfly.

While insect wings are widely recognised as multi-functional, recent work showed that this extends to extensive bactericidal activity brought about by cell deformation and lysis on the wing nanotopology. We now quantitatively show that subtle changes to this topography result in substantial changes in bactericidal activity that are able to span an order of magnitude. Notably, the chemical composition of the lipid nanopillars was seen by XPS and synchrotron FTIR microspectroscopy to be similar across these activity differences.

Marine antifouling from thin air.

The dynamic relationship between the settlement behaviour of marine biota (cells, spores, larvae) and the longevity of an entrapped air layer (plastron) on submersed superhydrophobic surfaces was systematically investigated. Plastron lifetime decreased with increasing hydrophobic polymer loadings, and was correlated with the settlement rate of a range of fouling species of varying length scale, motility and hydrophobic/hydrophilic surface preference. The results show that the level of fouling on immersed superhydrophobic surfaces was greater when plastron lifetimes were minimal, regardless of the length scale, motility and the surface preference of the organisms.

Diatom attachment inhibition: limiting surface accessibility through air entrapment.

Surfaces consisting of sub micron holes (0.420-0.765 μm) engineered into nanoparticle (12 nm) coatings were examined for marine antifouling behaviour that defines early stage settlement.

Bactericidal activity of black silicon.

Black silicon is a synthetic nanomaterial that contains high aspect ratio nanoprotrusions on its surface, produced through a simple reactive-ion etching technique for use in photovoltaic applications. Surfaces with high aspect-ratio nanofeatures are also common in the natural world, for example, the wings of the dragonfly Diplacodes bipunctata. Here we show that the nanoprotrusions on the surfaces of both black silicon and D.

Hierarchical surfaces: an in situ investigation into nano and micro scale wettability.

Two scales of roughness are imparted onto silicon surfaces by isotropically patterning micron sized pillars using photolithography followed by an additional nanoparticle coating. Contact angles of the patterned surfaces were observed to increase with the addition of the nanoparticle coating, several of which, exhibited superhydrophobic characteristics. Freeze fracture atomic force microscopy and in situ synchrotron SAXS were used to investigate the micro- and nano-wettability of these surfaces using aqueous liquids of varying surface tension.