Imagine if you took a water balloon and placed it on a bed of widely-spaced blunt nails. While the nails wouldn’t be pointy enough to pierce the balloon’s rubber skin, eventually the weight of the water would cause the rubber suspended between the nails to rupture. Well, it turns out that the clanger cicada uses the same principle to kill bacteria that settle on its wings. That finding could result in a new generation of antibacterial materials.
A team of Spanish and Australian scientists examined the cicada’s wings using a microscope, and discovered that they were studded with a matrix of nanoscale blunted spikes. When a bacterium lands on those spikes, it initially stays intact. Over time, however, its elastic outer membrane starts to sag down between the spikes. When those saggy bits can’t take the strain any more, they tear open, and the bacterium dies.
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The process is illustrated in the video below.
In order to confirm that this was the case, the scientists cooked some bacteria in a microwave oven, altering the elasticity of their skin. As expected, the stretchier the skin, the more likely the bacteria were to die when placed on a cicada wing – the nano-spikes weren't as effective at killing bacteria with more rigid skin, however.
According to the scientists, this is the first known instance of a living organism being able to eradicate microbes using only the shape of its biomaterial. It is now hoped that manmade materials based on the structure of the cicada wings could be used to kill bacteria on the surfaces of doorknobs, hand rails, and other often-germy items.
The research team was made up of scientists from Spain’s Universitat Rovira i Virgili and Institució Catalana de Recerca i Estudis Avançats, along with Australia’s Swinburne University of Technology and James Cook University. A paper on the research was recently published in Biophysical Journal.