Plasma is the fourth state of matter, after solids, liquids, and gases, and has been used for disinfection and sterilization for wound care and skin diseases, such as MRSA (methicillin-resistant Straphylococcus Aureus). A new study, “Effects of Cold Atmospheric Plasmas on Adenoviruses in Solution” published November 30, 2011 in the Journal of Physics D: Applied Physics, focuses on the effects of cold atmospheric plasma (CAP) to kill the adenovirus.
What is the Adenovirus?
Adenoviruses are a group of viruses that cause respiratory and intestinal illnesses. These illnesses are generally mild, but are highly contagious. Adenovirus illnesses include the common cold, croup, bronchitis, pneumonia, conjunctivitis, and intestinal tract illnesses. You can become infected with the adenovirus when a sick person coughs or sneezes and the germs land you, or on a surface that you touch.
One of the challenges that hospitals face is the inactivation of viruses. Theadenovirus is one of the most difficult viruses to kill because they are physically stable, can tolerate moderate increases in temperature, and their pH levels are relatively resistant. To disinfect, hospitals use either autoclaving or chlorine bleach. Scientists at the Max-Planck Institut für extraterrestrische Physik and Technische Universität München in Germany chose the adenovirus to find out if cold atmospheric plasmas could inactive this difficult virus. When the adenovirus was exposed to the CAP for 240 seconds, only one in a million viruses survived.
Decoded Science asked Dr. Julia Zimmerman, one of the authors of the study, how CAP worked to inactivate the adenovirus.
“Unfortunately the exact mechanisms are not known yet and still researched. Looking at a few single components produced by the plasma (Ozone, UV, etc.), it is clear that the produced amounts of these components alone would not be sufficient to achieve the inactivation rates we achieved. The production of an air plasma leads to approximately 600 chemical reactions. It seems to be the mix – “the plasma cocktail” – which inactivates the viruses so efficiently.”
Further research is needed on the specific mechanics of how the adenovirus is inactivated. However, it seems to be similar to the mechanics of the human immune system’s reaction to a virus attack.
How Does the CAP Device Work?
The plasma cocktail is apparently very effective at disinfecting against adenoviruses, but how easy is it to implement? Dr. Zimmerman explained how the CAP generating device works:
“The plasmas we create are cold plasmas (at approximately a few degrees above room temperature) under atmospheric pressure. For the plasma device used in the study with adenoviruses we used the surrounding air as the gas which we partly ionize. The plasma is created by many microdischarges. For this we use a flat sheet (made out of copper for example), an insulating sheet (Teflon for example) and a mesh grid. These three parts are sandwiched together. By applying high voltage to the flat copper sheet, microdischarges are produced between the mesh grid, which partly ionize the surrounding air. Our plasmas therefore consist of electrons, ions, atoms, radicals, reactive species (mainly reactive oxygen and nitrogen species as we use air), a little bit of UV light (far below the ICNIRP limits) and a little bit of heat.
All in all, our aim is to generate “safe plasmas” with regards to current through skin, UV production, toxic gas emission , etc.”
Adenovirus Prevention With Plasma
The CAP generating device could be used in hospitals to disinfect hands and equipment. In the future, patients may even be able to inhale the plasma to treat lung infections. Plasma may also be applied to blood before a transfusion to kill any infections in the blood.
To make this new technology available in hospitals, a few more steps will be needed, explains Dr. Zimmerman.
“In research: The next steps are to further analyze the effect of CAPs on microorganisms and to analyze the killing mechanisms in detail. Furthermore we will improve the plasma diagnosis and modeling.
Concerning applications: Prof. Morfill (Director of the Mack-Planck Institute for extraterrestrial physics) and his co-workers founded the company terraplasma GmbH. At the moment we are in negotiations with different industry companies and already signed two contracts for proof of principle phases. The aim is that terraplasma GmbH develops CAPs devices for specific purposes together with the interested company.”
Dr. Zimmerman also explained how CAP-based treatment will further the advancement in hygiene practices and treatment options for patients.
“As the produced plasma is cold and works against bacteria, viruses, fungi and spores, it could be used for several applications in hygiene (professional and personal) and medicine.
- Sterilization of heat sensitive materials (medical equipment and even for decontamination of satellites, space vehicles, etc)
- Sterilization of surfaces: we developed a device which could serve as a self sterilizing surface and therefore sterilize itself.
- Hand disinfection
- Disinfection of food
- Reduction of bacteria in chronic wounds: we are running a phase II study in two clinics at the moment where cold plasma is applied to chronic wounds in patients to improve wound healing.
- For disinfection of operational wounds
- Treatment of all kinds of skin diseases with bacteria, viruses or fungi as an origin.”
Benefits of Cold-Atmospheric Plasma for Disinfection
This new research has found a way to kill one of the most difficult viruses out there. This advance provides hope for treating other diseases, reducing infection, and possibly even preventing epidemics. CAP opens a new world for scientists, doctors, medical staff, and patient treatment protocols.
Centers for Disease Control and Prevention. Adenoviruses. Accessed on December 7, 2011.
The Institute of Physics. Plasma-based treatment goes viral. (2011). Accessed on December 7, 2011.
Zimmermann, J., et al. Effects of cold atmospheric plasmas on adenovirus in solution. (2011). Journal of Physics D: Applied Physics. 44 505201. Accessed December 7, 2011.
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