• The Financial District


A team of researchers from Purdue University in the US believes aerosols of foodcoloring dyes could potentially kill COVID-19 viruses lingering in the air and argues that photodynamic therapy has been effective in battling cancer.

Mihai Andrei wrote for ZME Science on August 22, 2020 that the team of Young Kim, Hee-Jae Jeon, Jung Woo Leem and Yuhyun Ji, said “Our biomedical engineering lab has developed a way to potentially neutralize viruses lingering in the air using aerosols of FDA-approved food coloring dyes. Aerosols are tiny bits of solid or liquid matter suspended in air. Our idea was inspired by photodynamic therapy, which is a medical treatment, including for certain types of cancer. Photodynamic therapy uses a photosensitizer, a chemical that reacts with oxygen in the presence of light, to produce oxygen free radicals. These radicals are highly reactive, meaning they trigger other chemical reactions, including ones that kill harmful pathogens.”

They said that instead of using expensive medical photosensitizers, they have identified several FDA-approved food coloring dyes that can be used to generate free radicals in visible light. “We use ultrasound to generate small aerosols containing thefood coloring so that the dyes can float and linger in the air. The aerosols are barely visible, and their small size and short lifespan in light means they don’t stain surfaces. We used this technique to produce a device, Photodynamic Airborne Cleaner, that disinfects pathogens floating in the air. To the best of our knowledge, this is the first-of-its-kind photodynamic therapy aerosol generator for airborne disinfection,” the team said.

“Photodynamic therapy was first demonstrated as a means of fighting bacterial infection. Oxygen free radicals, specifically singlet oxygen, can also inactivate viruses by damaging the nucleic acids, proteins and lipids that they are composed of. In particular, singlet oxygen is effective at breaking down the lipid envelopes that form protective shells around many viruses. Most of the viruses that are harmful to humans, including SARS-CoV-2, have these envelopes. Several other disinfection techniques are available, for example aerosolized hydrogen peroxide, hydrogen peroxide vapor, ozone, steam and UV-C or ‘deep UV’ illumination. However, these are more appropriate for disinfecting surfaces than disabling pathogens floating in the air. Also, they can be hazardous to humans. For example, deep UV is commonly used as a disinfectant, but is carcinogenic,” the team said.

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