Strange antibacterial effect of dragonfly wings

Understanding the structures and mechanisms on dragonfly surfaces will open a lot of applications for people in many fields, from health to food technology.

The material with a surface that is capable of killing itself is a well-researched topic with a very wide range of applications.

A research team used a special type of molecule to smooth the surface and disrupt the bacterial link to destroy them. Another group used silver in the form of nanoparticles to coat the surface to kill bacteria. Another group has a more daring idea, which is to use black silicon to create a surface with many nanopillar structures that can kill bacteria.

Winged dragonfly surface under a microscope.

In the black silicon surface method, we have a concept called nano-surface textured (Nano - Textured Surfaces) that already exists in the natural environment. The nanostructures of black silicon are similar to the structures on dragonfly wings. And the surface of the dragonfly wings is very good at killing bacteria.

According to the study, nanopillar " surface " surfaces will kill bacteria by straightening and penetrating the bacterial cell membrane. A group of Australian and Nigerian scientists used the technology of integrating many microscopes to give the most accurate explanation of the bactericidal ability of dragonfly wings in particular and the nanopillar surface in general. The result is a rather complex mechanism that has taken place to kill bacteria on the surface.

The first research clue is about the uneven height of the spines distributed on the surface of the dragonfly's wings, which is different from the previous conventional thinking. At the same time, more careful observation shows that bacteria do not come into direct contact with the thorns of the nanopillar surface.

Shape of extracellular polymer polymer layer.

Instead, the bacteria approach and connect to the nanopillar surface with the molecular structures they secrete called "extracellular polymers" (EPSs) , and these molecules are like a finger. Grow more to touch exposed surfaces.

The bacteria will be destroyed when moving.

When the bacteria come into contact with the surface, they will produce binding force with the spikes on the surface. These adhesives may cause deformation of their outer membrane. Without moving, the bacteria will still not be affected much. However, because of the thorny structure of the nanopillar surface, if the bacteria move, they will be subjected to adhesion forces causing surface injuries and nutrient leakage as well as destroying their outer shell.

According to the old model, the nanopillar surface spikes will directly pierce bacteria and this model is accepted by many researchers and considered as the standard. However, the research team proposed a new model based on the results achieved during the observation of experiments.

The new model shows the unevenness of the surface spikes as well as the rationality compared to the experimental results.

According to the model proposed by the group, the bacteria do not come into direct contact with the spines but through the molecular surface they secrete. When the bacteria move, they will be forced to cause surface wounds to protect and cause molecular leaks inside the cells, leading to the destruction of bacteria. At this point, new spikes stabbed deep inside the bacterial cell.

Old and new models for the mechanism of killing bacteria of nanopillar surfaces.

One of the limitations of the study was that the team only observed the experiment on E.Coli bacterial cells, Gram-negative and two-layer bacteria. Therefore more research is needed on Gram-positive bacteria and 1 coating to compare results.

Another drawback is that more experiments should be done on a group of bacteria that are unable to create an " exogenous polymer" to have a comparison of the most accurate bactericidal mechanism. In the end, the team also needed to study more about the nano-texture surfaces of uniform spikes to verify the bactericidal mechanism found by the team could be applied to this type of surface.

Again, mother nature surprised scientists because of the diversity and complexity of creation. Understanding the structures and mechanisms on dragonfly surfaces will open a lot of applications for people in many areas from health to food technology.