Molecular and Topographical Organization: Influence on Cicada Wing Wettability and Bactericidal Properties

Abstract

Numerous natural surfaces have micro/nanostructures that result in extraordinary functionality, such as superhydrophobicity, self‐cleaning, antifogging, and antimicrobial properties. One such example is the cicada wing, where differences in nanopillar geometry and composition among species can impact and influence the degree of exhibited properties. To understand the relationships between surface topography and chemical composition with multifunctionality, the wing properties of Neotibicen pruinosus (superhydrophobic) and Magicicada cassinii (hydrophobic) cicadas are investigated at time points after microwave‐assisted extraction of surface molecules to characterize the chemical contribution to nanopillar functionality. Electron microscopy of the wings throughout the extraction process illustrates nanoscale topographical changes, while concomitant changes in hydrophobicity, bacterial fouling, and bactericidal properties are also measured. Extract analysis reveals the major components of the nanostructures to be fatty acids and saturated hydrocarbons ranging from C17 to C44. Effects on the antimicrobial character of a wing surface with respect to the extracted chemicals suggest that the molecular composition of the nanopillars plays both a direct and an indirect role in concert with nanopillar geometry. The data presented not only correlates the nanopillar molecular organization to macroscale functional properties, but it also presents design guidelines to consider during the replication of natural nanostructures onto engineered substrates to induce desired properties.

Developmental, cellular, and biochemical basis of transparency in the glasswing butterflyGreta oto

“…In contrast to previously described highly ordered nipple arrays on insect eyes (41). Another study exploring the molecular organization of dragonfly wing epicuticle found that the major components identified were fatty acids and n-alkanes with even numbered carbon chains ranging from C 14 to C 30 (42).…”

Biomimetic Polymer Surfaces by High Resolution Molding of the Wings of Different Cicadas

“…The reduction in WCA, in comparison to their corresponding wing structures, demonstrates the change in topography as well as the change in surface chemistry. The outer epicuticle of cicada wings is mainly made up of fatty acids and long chain hydrocarbons that would contribute to the inherent hydrophobic nature of the wing nanostructures [ 20 ]. However, when the WCA of primary mold PEG surfaces was investigated, they were shown to be hydrophilic (WCA < 90°).…”

“…The effect of surface chemistry, in addition to topographic effects, cannot be overlooked when discussing bacterial adhesion on structured materials. Roman-Kustas et al have completed some important work on looking at both the chemical composition of cicada wings, as well as how changes in surface chemistry affects bacterial cell adhesion [ 20 , 21 ]. Their work concluded that the surface chemical constituents on the wing play a role in the antimicrobial activity of the wings, in addition to the surface structures.…”

Wing wettability gradient in a damselflyLestes sponsa(Odonata: Lestidae) reflects the submergence behaviour during underwater oviposition

“…All hydrophobic surfaces (CA > 90°) can be enhanced to superhydrophobicity by the addition of a certain type of topography [ 20 , 24 , 25 ]. This may be the reason why superhydrophobicity of insect wing cuticle has been studied extensively from a morphological point of view [ 1 , 3 , 11 , 12 , 26 – 28 ]. However, often, superhydrophobicity is a result of a combination of surface topography, comprising features both on the micro- (greater than 1 µm) and nanoscale (less than 200 nm), and chemical heterogeneity at the micrometre scale [ 7 , 13 , 16 , 29 – 31 ].…”