It looks like you're new here. If you want to get involved, click one of these buttons!
If you can read this message, please contact us immediately at the following email address:
We'd like to communicate.
Special bacteria-killing surfaces constitute a highly active area of research and development.
Strategies to construct them vary widely. One group has infused a slippery surface with molecules that disrupt bacterial communication. Others have shown that silver nanoparticle coatings can destroy bacteria. Yet another group used black silicon to create a surface that resembled a tiny "bed of nails" (nanopillars), which physically rip bacteria apart.
That latter example, which falls into a broad category known as nano-textured surfaces (NTS), is of particular interest because it also exists in nature. The nanostructure of black silicon is very similar to that of dragonfly wings. And just like their elemental counterpart, dragonfly wings kill bacteria.
It is widely thought that a "bed of nails" surface destroys bacteria through puncturing the cell wall. But in newly published research based on extensive use of various microscopy techniques, a team of Australian and Nigerian researchers demonstrated that an entirely different killing mechanism may be at play.
The first clue that the conventional wisdom was wrong came from the observation that nanopillars on dragonfly wings were not all the same height. (See image on right.)
This stands in contrast to synthetic "bed of nails" surfaces, which tend to produce nanopillars of equal height. A closer examination further demonstrated that the bacterial membrane does not come into direct contact with the nanopillars. Rather, bacteria (in this case, E. coli) attach to the nanopillars via structural molecules secreted by the bacteria, known as "extracellular polymeric substances" (EPSs), as well as by "finger-like" extensions. (See image on the left.)
Once the bacteria land on the surface, they are subjected to adhesive
forces. These can deform the bacterial membrane, but by themselves,
probably do not cause the bacteria to rupture.
Instead, the bacteria are essentially caught in one of those sinister
traps of which movie villains are quite fond. If they don't move, the
bacteria might survive. However, when they do move, shear forces pull
on the EPSs, ripping the membrane apart. This results in a
fatal leakage of cellular contents, which causes the cell to deflate
like a balloon.