Since the onset of the COVID-19 pandemic, eliminating the coronavirus from surfaces that are commonly interacted with has received significant attention from researchers. While it has been found that methods such as spraying of alcohol and exposure to UV light can effectively destroy the SARS-CoV-2 virus, more methods can add to the arsenal against it. Now, a new study has found that exposing surfaces laden with the pathogen to cold atmospheric plasma (CAP) can wipe them out completely.

According to the UCLA scientists, when coronavirus-laced surfaces such as plastic, metal and leather, were subjected to just 30 seconds of treatment using argon-fed CAP, the virus was destroyed completely. "These results demonstrate the great potential of CAP as a safe and effective means to prevent virus transmission and infections for a wide range of surfaces that experience frequent human contact," the authors wrote.

Novel Approach Towards Microbial Neutralization

Cold atmospheric plasma
Cold atmospheric plasma (Representational Picture) Facebook Screengrab/@Plasmatreat GmbH Steinhagen

What makes the novel coronavirus particularly potent is its high virulence. Research has shown that fomites—objects and surfaces that are contaminated with infectious agents—can play a crucial role in the transmission of the disease. Also, studies have demonstrated that the tricky pathogen can linger on certain surfaces for up to 28 days.

Therefore, the researchers sought to test whether plasma fed by argon—the third-most abundant gas in the Earth's atmosphere—could kill the SARS-CoV-2 virus effectively. Plasma is one of the four fundamental states of matter. It can be generated by heating a neutral gas (inert gas) or exposing it to a powerful strong electromagnetic field.

Though a comparatively novel technology, CAP has shown promise in dentistry, cancer treatments, wound healing, and other medical uses. CAPs are gases that have been partially ionized. They generate a reactive mixture of ions, electrons, heat, UV radiation, and reactive species (such as O3, NO, and NO2, among others). This mixture disables viruses, bacteria, spores, and fungi, along with odorous molecules efficiently.

Using Plasma to Destroy Coronavirus

Cold atmospheric plasma device
A schematic of UCLA’s cold atmospheric plasma device with an image of it in operation Wirz Research Group, UCLA

For the study, the author built an atmospheric pressure plasma jet using a 3D printer. This jet was used to spray plasma on surfaces that had been treated with cultures of the novel coronavirus. The surfaces that were tested included plastic, cardboard, metal, and the leather surfaces of basketball, baseball and football.

When the spray was fed by argon gas, it was found to completely destroy SARS-CoV-2 present on the six surfaces in less than three minutes. More significantly, it was observed that a majority of the virus was killed after 30 seconds. Upon further testing, the authors noted that the virulent pathogen was eliminated from cotton on face masks at similar times.

"This is only the beginning. We are very confident and have very high expectations for plasma in future work. In the future, a lot of answers for the scientific community will come from plasma," said Richard E. Wirz, corresponding author of the study, in a statement.

Safe And Healthy Alternative

Cold atmospheric plasma
Temperature distribution of Ar and He plasma-treated 6-well plates. Wirz Research Group, UCLA

The authors conducted a similar test against the coronavirus using plasma that was fed by helium. However, its effectiveness was found to be nowhere close to that of the argon-fed plasma. This was despite treating the surfaces for up to five minutes. The authors posited that this ineffectiveness could be attributed to low rates of reactive nitrogen and reactive oxygen in comparison to when argon was used.

Zhitong Chen, co-author of the study, announced that the team was in process of constructing a compact device that can be widely employed for the treatment of surfaces that are contaminated with SARS-CoV-2 using plasma.

He also stressed that CPA was a healthier and safer option when compared to other sterilizing methods, including those involving chemicals. "Everything we use comes from the air. Air and electricity: It's a very healthy treatment with no side effects," concluded Chen.