The “clanger cicada” can physically kill bacteria by poking and shredding them with tiny pointy structures that seem to look a little like an old fashioned cheese grater. Keep in mind that this happens at a very small spacial scale, so the relationship between objects is different than in normal human experience. Essentially, the membrane of a bacterium spreads itself over the pointy nano-spikes of the insect wing. This is a little like a failed “laying on the bed of nails” attempt, but where the force involved with the bed of nails is gravity, gravity has nothing to do with the bacterium interacting with the nano spikes. Also, the bacterium does not shred because the nano spikes pierce it. Rather, the bacterial membrane is stretched to breaking point and falls apart that way. From the write-up in Nature News:

The clanger cicada (Psaltoda claripennis) is a locust-like insect whose wings are covered by a vast hexagonal array of ‘nanopillars’ — blunted spikes on a similar size scale to bacteria (see video, bottom). When a bacterium settles on the wing surface, its cellular membrane sticks to the surface of the nanopillars and stretches into the crevices between them, where it experiences the most strain. If the membrane is soft enough, it ruptures…

Here’s the model:

Not all bacteria are subject to this effect; it depends on the rigidity of the cell membrane.

Obviously, we want to make all doorknobs and toilet seats out of this stuff.

Pogodin, Et Al. 2013. Biophysical Model of Bacterial Cell Interactions with Nanopatterned Cicada Wing Surfaces. Biophysical Journal 104(4):835-840. The article was published on Feb. 19th in Biophysical Journal. Abstract:

The nanopattern on the surface of Clanger cicada (Psaltoda claripennis) wings represents the first example of a new class of biomaterials that can kill bacteria on contact based solely on their physical surface structure. The wings provide a model for the development of novel functional surfaces that possess an increased resistance to bacterial contamination and infection. We propose a biophysical model of the interactions between bacterial cells and cicada wing surface structures, and show that mechanical properties, in particular cell rigidity, are key factors in determining bacterial resistance/sensitivity to the bactericidal nature of the wing surface. We confirmed this experimentally by decreasing the rigidity of surface-resistant strains through microwave irradiation of the cells, which renders them susceptible to the wing effects. Our findings demonstrate the potential benefits of incorporating cicada wing nanopatterns into the design of antibacterial nanomaterials.

Comments

  1. #1 Eu
    March 11, 2013

    Interesting… if only there were more bacteria that could be killed with pointy objects (Most can’t, right? Otherwise skip the water and just get your needles…?)

  2. #2 Greg Laden
    March 11, 2013

    The way that bacteria attach to things, which is what we are seeing here, essentially, could be used against them. Bacteria involved in UTI survive between bouts by attaching themselves to urinary tissues. Some chemicals are known to interfere with that and may thus reduce chance of infection (the thing in cranberry juice, proanthocyanidin).

    I quickly add: cranberry juice is not known to be good at treating UTIs. The question is, does regular consumption of the juice reduce recurrence of UTI’s in women who tend to get them easily. The available evidence suggests that this may be true, but it is not conclusively proven. The cranberry juice thing is more interesting because of what it reveals about how regular people as well as scientists react to incomplete information. See this: http://scienceblogs.com/gregladen/2010/08/13/does-cranberry-juice-help-repr/