Science

Black silicon slices and dices bacteria

Black silicon slices and dices...
The spiky surface of black silicon shred certain types of bacteria, offering the potential of new antibacterial surfaces
The spiky surface of black silicon shred certain types of bacteria, offering the potential of new antibacterial surfaces
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The surface structure of black silicon is similar to the surface of the wings of the Wandering Dragonfly
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The surface structure of black silicon is similar to the surface of the wings of the Wandering Dragonfly
The spiky surface of black silicon shred certain types of bacteria, offering the potential of new antibacterial surfaces
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The spiky surface of black silicon shred certain types of bacteria, offering the potential of new antibacterial surfaces

Originally discovered by accident in the 1980s, black silicon is silicon with a surface that has been modified to feature nanoscale spike structures which give the material very low reflectivity. Researchers have now found that these spikes can also destroy a wide range of bacteria, potentially paving the way for a new generation of antibacterial surfaces.

Surface structures similar to black silicon can be found in nature. Earlier this year, researchers at the Swinburne Institute of Technology in Australia led by Professor Elena Ivanova and Professor Russell Crawford found that the wings of the cicada Psaltoda claripennis could shred certain types of rod-shaped bacteria.

This prompted them to seek out other insects with similar spike-like surface architectures. They found that the wings of the Diplacodes bipunctata or Wandering Percher dragonfly were even more deadly, killing both rod-shaped and spherical bacteria.

The surface structure of black silicon is similar to the surface of the wings of the Wandering Dragonfly
The surface structure of black silicon is similar to the surface of the wings of the Wandering Dragonfly

"This structure generates a mechanical bacteria killing effect which is unrelated to the chemical composition of the surface," says Professor Crawford, who is Dean of the Faculty of Life and Social Sciences at Swinburne.

The team then set out to mimic the surface structure of the Wandering Percher dragonfly wing in an effort to create a surface with similar bacteria-killing properties. They then compared the bacteria-killing capacity of their black silicon creation to the dragonfly wing.

"Both surfaces were found to be highly effective against a range of bacteria, as well as endospores," says Professor Crawford. "They exhibited estimated average bacteria killing rates of up to 450,000 cells per minute of exposure, for every square centimeter of available surface."

Among the variety of bacteria the surfaces were able to kill were the deadly strains of the Staphylococcus aureus or golden staph bacterium.

"This represents an exciting prospect for the development of a new generation of antibacterial nanomaterials that could be applied to the surfaces of medical implants, making them far safer," he adds.

The team has published its findings in the journal Nature Communications.

Source: Swinburne Institute of Technology

5 comments
Siegfried Gust
And what happens after the surface is covered in shredded bacteria? I imagine that it would be difficult if not impossible to clean afterwards. The tiny spikes would make wetting it very difficult due to surface tension. My guess is that that is why the insects have similar surface structure, to repel water rather than bacteria.
kpkpkp
@Siegfried Gust: Insects don't usually encounter detergents, but your stuff will.
kuryus
If the spikes will shred bacterial cells, won't they shred human cells too? It looks like an implant with this type of surface would rasp its way thru a person.
Rafael Kireyev
I propose to impose a black silicon on the blades of all our ventilators in order they could shoot down Staphylococcus aureus on the fly.
Tom Billings
"If the spikes will shred bacterial cells, won't they shred human cells too? It looks like an implant with this type of surface would rasp its way thru a person. " Different scales. Most bacteria are far smaller than human cells. For the same reason, I would bet that many intestinal worm parasites would not be affected by this surface, nor paramecium species. Both to human touch and to our cells this surface should be a dull black, and no more.