This simple mix of dye and light could decontaminate masks for reuse

It's a novel application of a simple solution — and should it be effective, it could have an impact on mask shortages on a global scale.

Belinda Heyne, professor of chemistry at the University of Calgary, is part of a team who worked to develop a new method that uses a cheap blue dye and light in order to decontaminate medical masks.

"The dye, which is called methylene blue, [is] activated by indoor light. The methylene blue, through its activation, is enabling to take out the energy of the light and giving it to the ambient oxygen that we have around us," Heyne said.

"That's energizing oxygen, and then the oxygen is becoming reactive, and this is what is killing the virus."

Global research study

Heyne is part of a global research consortium that includes the World Health Organization, tasked with investigating alternative decontamination methods for medical masks.

At present, medical masks are designed to be used once. But with some infectious disease experts calling for double masking as variants spread, high numbers of masks will soon be required.

"The amount of masks which are used on a daily basis, it's not sustainable. And some countries are going to have a shortage again," Heyne said. "So how can we prevent the shortage and ensure the safety of our front-line workers?

"This is really what the study has proven — we have created a very cheap methodology, which is enabling [us] to disinfect the masks."

Simple and inexpensive

Utilizing the solution containing the methylene blue dye, Heyne said the next step involves spraying the solution on the surface of the mask — six sprays on the outside, two on the inside.

"We place the mask with the methylene blue sprayed on under a very bright light," she said, adding that such a lamp could be purchased at any home improvement retailer.

To irradiate the mask at the top and the bottom, researchers use a lamp on each side. If only one light is available, masks can be flipped around.

"The entire study has proven we can kill the virus. But in addition to killing the virus, the masks are keeping their integrity, so we are not damaging the mask," Heyne said.

Results surrounding fabric and cloth masks are less conclusive, Heyne said.

"Our results are variable there. It doesn't mean that the methodology doesn't work, it's simply that the fabric, the protocol was harder for us to quantify, appropriately, the virus," she said. "It was much easier to do it on the other mask."

Though the process might be relatively inexpensive in Canada, Heyne said next steps for the researchers involve learning how to potentially use sunlight to activate the dye in order to benefit low- and middle-income countries.

Next steps and safety

Heyne said researchers are still taking steps to ensure the process is 100 per cent safe, but noted that methylene blue is FDA-approved.

"I wouldn't want people to be going and buying out of Amazon. Obviously, we're conducting studies right now to make sure that we are using concentrations that are safe for humans to be using," she said.

"The amount of dye we have, which is very negligible, is like taking a teaspoon and putting it into a swimming pool."

The group is currently trying to publish its paper, which includes the names of 49 authors, into a scientific journal. The WHO listed the process as a potential method for disinfection of masks as part of a document dated Dec. 23, 2020.

"How is it important and who is it going to impact? It can impact everyone," Heyne said.