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The Science Behind How Dragonfly Wings Kill Bacteria (And How We Might Use This Information)

Special bacteria-killing surfaces constitute a highly active area of research and development.

Strategies to construct them vary widely. One group has infused a slippery surface with molecules that disrupt bacterial communication. Others have shown that silver nanoparticle coatings can destroy bacteria. Yet another group used black silicon to create a surface that resembled a tiny "bed of nails" (nanopillars), which physically rip bacteria apart.

That latter example, which falls into a broad category known as nano-textured surfaces (NTS), is of particular interest because it also exists in nature. The nanostructure of black silicon is very similar to that of dragonfly wings. And just like their elemental counterpart, dragonfly wings kill bacteria.

It is widely thought that a "bed of nails" surface destroys bacteria through puncturing the cell wall. But in newly published research based on extensive use of various microscopy techniques, a team of Australian and Nigerian researchers demonstrated that an entirely different killing mechanism may be at play.

The first clue that the conventional wisdom was wrong came from the observation that nanopillars on dragonfly wings were not all the same height. (See image on right.)

This stands in contrast to synthetic "bed of nails" surfaces, which tend to produce nanopillars of equal height. A closer examination further demonstrated that the bacterial membrane does not come into direct contact with the nanopillars. Rather, bacteria (in this case, E. coli) attach to the nanopillars via structural molecules secreted by the bacteria, known as "extracellular polymeric substances" (EPSs), as well as by "finger-like" extensions. (See image on the left.)

Once the bacteria land on the surface, they are subjected to adhesive forces. These can deform the bacterial membrane, but by themselves, probably do not cause the bacteria to rupture.  Instead, the bacteria are essentially caught in one of those sinister traps of which movie villains are quite fond. If they don't move, the bacteria might survive. However, when they do move, shear forces pull on the EPSs, ripping the membrane apart. This results in a fatal leakage of cellular contents, which causes the cell to deflate like a balloon.

People in this world look at things mistakenly, and think that what they do not understand must be the void. This is not the true void. It is bewilderment.
- Miyamoto Musashi, The Book of Five Rings


  • Matt_ADMIN_Matt_ADMIN_ Administrator
    Super-duper interesting, and perhaps all the more important now that all our chemicals are supposedly failing
    "...Say, 'GOD is sufficient for me.' In Him the trusters shall trust." (Quran 39:38)
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