Researchers put anti-microbial mask coatings to the test. Triiodide, salt, and graphene-nano silver take their turn on the lab bench.

Face masks with COVID-fighting coatings may be the next frontier in PPE. At least one such mask is available commercially in Canada – using a triiodide coating – and researchers are investigating the virus-busting powers of a host of other substances, including salt and nano-silver.

In July, University of Toronto researchers announced a triiodide coating developed by Quebec company I3 BioMedical Inc. can deactivate, within minutes, more than 99 per cent of the virus that causes COVID-19 on the outer surface of medical masks.

“(The company) had done this before with other bacterial and viral pathogens including influenza, and we extended these studies for them to show that SARS-CoV-2 was also susceptible,” molecular geneticist Scott Gray-Owen said in a news release.

The company’s executive chairman, Pierre Jean Messier, says the triiodide coating kills by oxidizing microbes’ cell walls. He says there is no danger to breathing in triiodide because the exposure falls far below accepted levels.

One of the benefits of a quick-acting coating is that masks are less likely to be a source of contamination as people unused to wearing them adjust them. Even without masks, studies show we tend to touch our faces every four minutes or so.

While the bulk of I3 BioMedical’s sales have been to Japan, says Messier, it has been selling its masks to medical suppliers in Canada since 2011 and began selling them online to the general public this summer.

Vaccine research leads to ‘Aha’ moment

Meanwhile, at the University of Alberta, chemical and materials engineer Hyo-Jick Choi, MCIC published research three years before the COVID-19 pandemic showing salt-coated masks can inactivate more than 99 per cent of the influenza virus within five minutes. In a 2020 paper, he and his team followed up with similar results against five different bacteria (K. pneumoniae, MRSA, P. aeruginosa, S. pyogenes and E. coli).

“If salt recrystallization can break down the walls of these bacteria, it can break down everything,” says Choi.

While he does not have access to a lab approved for working with the COVID virus, he is currently testing the salt-coating’s performance against two coronaviruses similar in structure to SARS-CoV-2 and hopes to eventually test it against the virus itself.

Choi’s ‘Aha’ moment about salt’s virus-killing potential happened several years ago while trying to come up with a reliable way to ensure the long-term storage of oral vaccines.

Vaccine solutions are often mixed with sugar before the water is removed and it is dried out. This process helps keep the vaccine stable, but sometimes sugar can recrystallize as it dries, destroying the vaccine.

“It got me thinking,” Choi recalls. “The vaccine is made from an inactivated virus and the shape is the same as the active virus.” If recrystallization destroys the vaccine, he reasoned, it should also destroy the virus.

Choi says he decided to work with salt, rather than sugar, because it recrystallizes more reliably. The salt is non-toxic and tests showed the coating doesn’t make it any harder to breathe through the mask. Choi says he hopes to get his mask to market by the end of 2021.

Silver linings

In Guelph, Ontario, ZEN Graphene Solutions has developed a graphene and nano-silver coating that testing at Western University shows is 99 per cent effective against the COVID-19 virus.

The company, which calls it a virucidal ink, provided researchers with samples at different concentrations, which were applied to N95 mask fabric and then exposed to the SARS-CoV-2 virus. Researchers found the ink was still able to kill 99 per cent of the viruses 35 days after application to the mask material.

The coating is a combination of oxidized graphene and nano-silver cations. The silver cations hold on through an ionic bond instead of a covalent one, says CEO Francis Dube.

“So when the virus comes in on a droplet, the graphene oxide is hydrophilic and the water will disperse on it easily. Then the ionic bonded silver comes off the graphene oxide and into the water droplet and attacks the virus,” he says.

Dube says the company is running tests now to ensure the nano-silver is not harmful to breathe in.

“The amounts we’re using are really low,” he says, adding the company has filed a provisional patent on the coating and is developing plans to commercialize it once it gets regulatory approval.