COVID shield: spray coating to protect the surface

image: The spray will soon be marketed.
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Credit: Image: Cesar Nicolas, University of Melbourne

A first-of-its-kind sprayable coating that can prevent the surface spread of infection by bacteria and viruses – including COVID-19 – over an extended period of time – has been developed by a team of Australian researchers.

Described in the newspaper Advanced sciences, the spray works in two ways: repelling viruses and bacteria through an air-filled barrier and killing pathogens through microscopic materials if the diaper is damaged or submerged for long periods of time. The spray uses a combination of plastics strong enough to be considered an alternative to bulletproof glass.

The coating provides a reliable alternative to standard disinfectants, which become less effective and require regular reapplication, and is the only permanent surface layer proven to protect surfaces from virus contamination. It’s safer than existing disinfectant alternatives, with no harmful side effects, and more stable potency – unlike the second most promising non-disinfectant that kills bacteria, silver nanoparticles.

The authors said the coating could be applied to surfaces in public places such as elevator buttons, stair railings, surfaces in hospitals, nursing homes, schools and restaurants, for prevent the spread of common viruses and bacteria.

Co-lead author from the University of Sydney School of Biomedical Engineering, Professor Antonio Tricoli and Director of the University of Melbourne’s Graeme Clark Institute, Professor David Nisbet, said the spread of Viral and bacterial pathogens through contact with surfaces is one of the leading causes of infection worldwide. Surface contamination also plays a major role in the evolution of antibiotic resistant bacterial strains.

“Without a barrier, viruses such as coronaviruses can remain on surfaces and remain infectious for up to a week. Other viruses such as reoviruses, which can cause colds or diarrhoea, for example, can remain on surfaces for several weeks, causing large outbreaks in healthcare and elderly care settings, said the Professor Tricoli.

“Like a lotus leaf, the surface spray creates a coating that repels water. Because pathogens like to be in water, they stay trapped in the droplets and the surface is protected from contamination. If this mechanism fails, a secondary burst of ions is triggered by carefully engineered nanomaterials dispersed throughout the coating,” said Prof. Tricoli.

The spray was developed over a five-year collaboration by the multi-university research team and was partly funded by Australian Research Council and NHMRC grants.

The team tested the mechanical stability and surface energy of the coating. They also tested its ability to resist contamination from bacteria and viruses by subjecting it to high concentrations of both. The samples were immersed for long periods and the sprayed surfaces were deliberately damaged to test the resilience of the spray against their contamination.

“We have identified the mechanical processes underlying how the spray works and quantified its effectiveness in different environments,” said Professor Nisbet.

“For this study, we tested metal surfaces. However, in the past we have shown that the spray can be applied to any surface, for example blotting paper, plastic, bricks, tiles, glass and metal. Our coating successfully inhibited up to 99.85% and 99.94% of the growth of bacterial strains. We also saw an 11-fold reduction in viral contamination. »

The spray is applied the same way as spray paint, although smaller amounts are needed.

“The coating was designed using a simple and scalable technique with a careful choice of materials to provide ultra-durability. We also believe that our explanation of the mechanism behind the antimicrobial and antiviral effects could significantly advance research into technologies anti-pathogens which could see the affordable manufacture of an effective surface spray to protect people against viruses and bacteria,” said Professor Nisbet.

The researchers created a startup to advance the technology and make the spray commercially available, potentially within three years.

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