Believe it or not: Artificial coloring could be used to disinfect the air from COVID-19
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Editor's Note: This research report is a brief overview of interesting academic work.
The big idea
Our Biomedical Engineering laboratory has developed a way to potentially neutralize airborne viruses using food coloring sprays approved by the FDA, the US health agency. Aerosols are small pieces of solid or liquid matter suspended in the air.
Our idea was inspired by photodynamic therapy , which is a medical treatment, even for certain types of cancer. Photodynamic therapy uses a photosensitizer, a chemical that reacts with oxygen in the presence of light to produce free oxygen radicals . These radicals are highly reactive, meaning that they trigger other chemical reactions, including those that kill harmful pathogens.
Instead of using expensive medical photosensitizers, we have identified several FDA-approved food dyes that can be used to generate free radicals in visible light. We use ultrasound to generate tiny sprays that contain the food coloring so the dyes can float and stay in the air. Sprays are barely visible and their small size and short shelf life mean they don't stain surfaces.
We use this technique to produce a device, Photodynamic Airborne Cleaner, that disinfects airborne pathogens. To the best of our knowledge and belief, this is the first photodynamic therapy aerosol generator for airborne disinfection.
Why does it matter?
Viruses and bacteria are often transmitted through the air. A person infected with SARS-CoV-2, the virus that causes COVID-19, who coughs or sneezes produces contaminated droplets and aerosols that float in the air and can trigger the disease .
Due to this risk, all types of indoor meetings are now limited. Being able to disinfect large volumes of indoor air where there are many people is essential to reduce the chances of transmission.
What other research is being done in this field?
Photodynamic therapy was first demonstrated as a means of fighting bacterial infections . Oxygen free radicals, specifically singlet oxygen , can also inactivate viruses by damaging the nucleic acids, proteins, and lipids that make them up. In particular, singlet oxygen is effective in breaking down the lipid envelopes that form protective layers around many viruses. Most viruses that are harmful to humans, including SARS-CoV-2, have these envelopes.
Various other disinfection techniques are available, for example hydrogen peroxide spray, hydrogen peroxide vapor, ozone, steam, and UV-C or 'deep UV' lighting. However, these are more appropriate for disinfecting surfaces than for disabling airborne pathogens. Additionally, they can be dangerous to humans. For example, deep ultraviolet rays are commonly used as a disinfectant, but they are carcinogenic.
We are preparing to collaborate with a federal research team to evaluate the effectiveness of our airborne photodynamic cleaner against airborne transmission of SARS-CoV-2.
FDA approved food coloring sprays and their singlet oxygen generation do not last long. These dye sprays degrade in light and singlet oxygen is not generated without light. However, although the food coloring is approved by the FDA for consumption, it is necessary to test the safety of possible inhalation and oral intake.