With hundreds of millions of years of trial and error under its belt, nature has been a great inspiration for many technologies. Now, nature might also be able to provide us with a solution to one of the biggest problems facing medicine: the ability to kill bacteria.
The wings of dragonflies have an incredible antibacterial property, and by harnessing this ability researchers hope they may be able to make antibacterial surfaces. A new study, published in Applied Materials & Interfaces, may have uncovered the secret of how dragonflies achieve this impressive feat, which could be of benefit in a range of situations, from hospitals to space exploration.
Looking at the intricate surface structure on the wings of dragonflies, the researchers noticed something unusual. It had long been thought that the wings were able to kill the bacteria due to the fine nano-textured surface that resembles a bed of spikes, which physically puncture the cell walls of the bacteria and thus kill it. However, a closer look revealed that these spikes were not of uniform length as would be expected, but of varying heights.
The nanostructure of a dragonfly wing. Bandara et al. 2017
Further examination of the bacteria interacting with the surface also found another significant discovery. The cell walls of the bacteria never actually come into physical contact with the surface. Instead, the bacteria release structural molecules that act as a glue, sticking the microorganisms to the wing. So how, then, do the wings manage their impressive antimicrobial feat?
It turns out that the clue is in the varying heights of the spikes on the nano-textured surface. The bacteria don’t die as soon as they land on the wings; in fact, they could actually survive if they stayed in one place. But as soon as they start to move, the spines hold tight to the bacterial “glue” and the shearing forces exerted on the microorganisms simply tear them apart, fatally spewing their cellular contents.
The experiments conducted for this study need further exploration, namely seeing if the same process occurs for all types of bacteria, not just the gram-negative ones tested, as well as seeing if spikes that are all the same length have the same effect.
The finding could help lead to the production of surfaces that kill bacteria on their own, without the need to coat them with antibacterial chemicals. This could be vital in a clinical setting, in which there is concern that the overuse of antibacterial drugs are leading to microorganisms developing resistance that could be fatal to patients. It may also be of use to those searching for life on other planets, as contamination by Earth bacteria is a very real concern.