Quirks & Quarks

Canadian scientists engineer self-cleaning surface that can repel dangerous bacteria

This material could help prevent bacterial contamination from spreading in the food and healthcare industries

This material could help prevent bacterial contamination from spreading in the food and healthcare industries

The self-cleaning material was only added to the left side of the stethoscope chest piece where there is very little bacteria compared to the untreated side on the right. (McMaster University)
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To create a microbe-repelling surface scientists borrowed a handy trick from the lotus leaf — its self-cleaning properties.

"When a droplet of rain comes onto the surface of the leaf, it actually bounces back, it doesn't like the surface," said biomedical engineer Tohid Didar, in conversation with Quirks & Quarks host Bob McDonald.

He and his team were inspired by the lotus to create an innovative solution to curb the spread of bacteria, including potentially deadly antibacterial resistant bacteria. 

Didar and his colleagues at McMaster University in Hamilton, developed a non-stick coating they could apply to plastic that in turn they can shrink-wrap onto surfaces — such as a stethoscope or a doorknob. This could prevent bacteria from colonizing these objects and forming a fortress-like biofilm.

When bacteria attach to a surface, they form communities that create a layer of slimy, slippery biofilm that protects the microbes from scrubbing, disinfectants and even antibacterial compounds. 

"Sometimes a sink in a hospital gets so contaminated, that they need to completely remove a sink and put a new one in," said Didar. 

This technology could be important in the battle against superbugs. According to Health Canada, antibiotic resistant superbugs are currently the fourth leading cause of death in our country — a problem experts expect to get a lot worse as more bacteria evolve resistance to our current roster of antibiotic medications.

Reverse-engineering the surface of a lotus leaf

If you were to zoom right down to the surface of the lotus leaf, you'd see a structure kind of like a series of rolling hills, covered in trees and then flowers on those trees. This surface is slippery because these structures trap air pockets between themselves and water droplets, for example. The water droplets then slide like pucks on an air-hockey table.

Didar and his colleagues created a surface that emulates this.  In includes microstructures 10 times smaller than the width of a human hair, which he said are the equivalent of the rolling hills. 

On top of the microstructure, they added nanostructures 1000 times smaller than a human hair that you can think of as the trees. 

Then on top of that layer, they added Teflon-like fluorinated chemicals to mimic the lotus leaf's waxy layer, equivalent to the flowers on the trees.

In total this structure works much like the lotus leaf, and bacteria find it as slippery and hard to stick to as water droplets.

Video showing self-cleaning material on top of untreated plastic over a dish of meat to demonstrate how water droplets — and bacteria would — bounce right off the treated surface. (McMaster University)

Superbug repelling material can be applied to any surface

Didar and his McMaster University colleagues tested their self-cleaning surface with three different superbugs: Staphylococcus aureus (MRSA), Pseudomonas aeruginosa and E. coli.

Their material prevented approximately 90 per cent of the bacteria from attaching to the surface, but more importantly, they were able to prevent the formation of biofilm, which Didar said is key to prevent contamination that would allow another person to pick up and transfer elsewhere.

Produced and written by Sonya Buyting

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