Inactivation of viruses with cold plasma technologies

Finger under plasma with species

Cold atmospheric pressure plasma jet used in this work impinging on a finger. Important reactive species for biological interactions are schematically depicted.

Infection control in healthcare and the food industry is of increasing importance in today’s society. Major concerns include the growing resistance of bacteria to antibiotics and the large numbers of gastroenteritis and diarrheal disease outbreaks. Food-borne bacteria and viruses particularly in minimally processed or fresh foods have been implicated in many outbreaks of gastroenteritis worldwide and are a real threat to public health.

Ensuring food safety and infection control in hospitals have become an extremely complex task due to the large scale and increasingly global nature of our society. Currently used decontamination methods often lack antimicrobial and antiviral effectiveness or are expensive. Many new technologies are developed and investigated to tackle these important societal challenges. A very promising technology in this area is cold plasmas – the topic of this recently published study in JPhysD, part of our recent special issue on plasma medicine.

Cold plasmas are ionized gases generated by high voltages in an open atmospheric pressure air environment operating at close to ambient temperatures. The produced electric field accelerates electrons whose energetic collisions with gas molecules leads to ionization, dissociation of molecules, and formation of UV radiation and reactive species such as hydrogen peroxide, nitric oxide, hydroxyl radical, ozone, peroxynitrate and singlet oxygen. These species form a complex reactive cocktail with antibacterial and antiviral properties. The bactericidal and virucidal efficacy of cold plasma is known but it is unclear which species are responsible for the inactivation, particularly for viruses.

The authors performed detailed inactivation studies of feline calicivirus, a surrogate for human norovirus, for various plasma conditions producing different reactive species cocktails. The effect of selected scavengers on the inactivation complemented with positive control measurements of relevant reactive species and a proteomics study revealed two distinctive inactivation pathways based on singlet oxygen and peroxynitrous acid. The first mechanism is favored in the presence of oxygen and the second in the presence of air when a significant pH reduction is induced in the solution by the plasma. The cold plasma produced H2O2, O3 and NO2 contributed to the observed inactivation.

The increased understanding of the cold plasma inactivation process will allow us to engineer and optimize more effectively cold plasma technology for disinfection applications.

About the authors

Dr. Urvashi Gangal is a Research Associate in the Department of Mechanical Engineering, University of Minnesota. She earned her doctorate degree in chemistry on the topic of glow discharge electrolysis and has more than seven years of experience in plasma induced liquid phase chemistry. Her research interests are plasma medicine, plasma liquid interactions and plasma as a tool for synthesis of polymers and nanomaterials.

Hamada A. Aboubakr: is a PhD student at the University of Minnesota. His PhD research project focuses on the use of novel non-thermal technologies, particularly cold plasma technology, for decontamination of food and food-contact surfaces from foodborne viruses such as human norovirus and hepatitis virus type A. He is also interested in food safety and food science, industrial and applied microbiology, enzymology, biochemistry and food analysis.

Dr. Mohamed M.M. Youssef is a food technologist with 48 years of experience in food technology, chemistry and analysis. He is currently a Professor in the Department of Food Science and Technology, Faculty of Agriculture, University of Alexandria, Egypt. His area of research includes formulation of novel functional foods with special focus on bioactive compounds such as natural antioxidants and dietary fiber (prebiotics). He is also interested in enzymology, biochemistry and virology.

Dr. Sagar M. Goyal is a virologist with more than 45 years of experience in animal virology. He is a Professor in the Department of Veterinary Population Medicine and is faculty advisor for Diagnostic Virology and Serology laboratories of the Minnesota Veterinary Diagnostic Laboratory. His area of research in animal virology includes disease pathogenesis, rapid diagnosis, and prevention and control of viral infections in animals and poultry. Other areas of interest include environmental microbiology and detection of small amounts of viruses from large quantities of food, water, and air.

Dr. Peter J. Bruggeman is the Richard and Barbara Associate Professor of Mechanical Engineering at the University of Minnesota. His primary research interests are in plasma-liquid interaction, plasma kinetics, plasma diagnostics and non-equilibrium plasma chemistry applied to plasma processes for environmental, biomedical and renewable energy technologies. Professor Bruggeman is also the Section Editor for the low-temperature plasmas and plasma-surface interactions section of JPhysD.

CC-BY logoThis work is licensed under a Creative Commons Attribution 3.0 Unported License. Image © Santosh Kondeti.

Categories: Journal of Physics D: Applied Physics

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