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How do dragonfly wings keep bacteria away?

A new and surprising mechanism for removing bacteria from the wings of the dragonfly, without physical contact of the bacterial cell membrane with the surface of the wings.

Photo: Alvesgaspar, Edited by Fir0002, Wikimedia.
Photo: Alvesgaspar, Edited by Fir0002, Wikimedia.

By: Yael Halfman Cohen 

The surface in nature, which is often designed in different nanometer topographies, is critical for the adaptation and survival of the organism. Shark skin, for example, excels in keeping bacteria away thanks to the nanometer structure of teeth, which prevent bacterial colonies from spreading on the skin.

The study was recently published in the academic journal Applied Materials & Interfaces Examine the interaction of E. coli bacteria with dragonfly wings. The researchers noticed an unusual feature in the dragonfly's wings. While previous studies estimated that the dragonfly's wings have the ability to eliminate bacteria thanks to a nanometer structure reminiscent of a bed of thorns or columns, the researchers discovered that the thorns are not of uniform length, but of varying lengths. It also became clear in the study that the bacterial cells did not come into physical contact with the surface. The bacteria released structural molecules that functioned as glue, and these stuck the bacteria to the wings. The bacterium could have survived if it had remained in place, but as it moved, the spikes held tightly to the glue, and the shearing forces applied to them simply tore the bacterium apart, spilling their cellular contents.

The researchers intend to perform additional experiments in order to understand if this mechanism works on different types of bacteria, beyond the type tested (e.g. non-sonic), as well as to test if spikes of the same height will have a similar effect of tearing the bacteria.

Removal of bacteria and their elimination has significance for medical and hygienic needs. The findings could lead to the development of antibacterial biomimetic surfaces and eliminate the need for antibacterial chemical coatings. It is known that extensive use of chemical substances may cause the development of resistance among the bacteria, a situation that may be fatal. A smart and elegant structural mechanism based on the structure of dragonfly wings, can bring the required performance more efficiently.

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