Reactive oxygen species (ROS) and the closely related reactive nitrogen species (RNS) are often generated in applications of atmospheric pressure plasmas intended for biomedical purposes. These species are also central players in what is sometimes referred to as ‘redox’ or oxidation‐reduction biology. Oxidation‐reduction biochemistry is fundamental to all of aerobic biology. ROS and RNS are perhaps best known as disease-associated agents, implicated in diabetes, cancer, heart and lung disease, autoimmune disease and a host of other maladies including ageing and various infectious diseases. These species are also known to play active roles in the immune systems of both animals and plants and are key signalling molecules, among many other important roles. Indeed, the latest research has shown that ROS/RNS play a much more complex and nuanced role in health and ageing than previously thought. Some of the most potentially profound therapeutic roles played by ROS and RNS in various medical interventions have emerged only in the last several years. Recent research suggests that ROS/RNS are significant and perhaps even central actors in the actions of antimicrobial and anti-parasite drugs, cancer therapies, wound healing therapies and therapies involving the cardiovascular system. Understanding the ways ROS/RNS act in established therapies may help guide future efforts in exploiting novel plasma medical therapies. The importance of ROS and RNS to plant biology has been relatively little appreciated in the plasma biomedicine community, but these species are just as important in plants. It appears that there are opportunities for useful applications of plasmas in this area as well. (Some figures may appear in colour only in the online journal)

https://iopscience.iop.org/article/10.1088/0022-3727/45/26/263001/pdf

The emerging role of reactive oxygen and nitrogen species in redox biology and some implications for plasma applications to medicine and biology

Reactive species in non-equilibrium atmospheric-pressure plasmas: Generation, transport, and biological effects

Cold atmospheric plasma (CAP) treatment of living tissues becomes a popular topic in modern plasma physics and in medical sciences. The plasma is capable of bacterial inactivation and noninflammatory tissue modification, which makes it an attractive tool for wound healing and the treatment of skin diseases and dental caries. There are still many open issues with regard to the mechanisms of action of the plasma on bacteria and mammalian cells and tissues, both from the biological and the physical perspective. For example, the chemistry of CAP and the exact roles of various plasma constituents in tissue treatment are not yet fully resolved. In this paper, we shall concentrate on the charged species (electrons and ions) in the plasma. The selected physical properties of typical atmospheric plasma sources will be discussed; experiments will be confronted with theoretical considerations, and several biomedical aspects of CAP treatment will be surveyed.

Cold Atmospheric Plasma: Charged Species and Their Interactions With Cells and Tissues

Background Cold plasma is an emerging non-thermal disinfection and surface modification technology which is chemical free, and eco-friendly. Plasma treatment of water, termed as plasma activated water (PAW), creates an acidic environment which results in changes of the redox potential, conductivity and in the formation of reactive oxygen (ROS) and nitrogen species (RNS). As a result, PAW has different chemical composition than water and can serve as an alternative method for microbial disinfection. Scope and approach This paper reviews the different plasma sources employed for PAW generation, its physico-chemical properties and potential areas of PAW applications. More specifically, the physical and chemical properties of PAW are outlined in relation to the acidity, conductivity, redox potential, and concentration of ROS, RNS in the treated water. All these effects are in microbial nature, so the applications of PAW for microbial disinfection are also summarized in this review. Finally, the role of PAW in improving the agricultural practices, for example, promoting seed germination and plant growth, is also presented. Key findings and conclusions PAW appears to have a synergistic effect on the disinfection of food while it can also promote seedling growth of seeds. The increase in the nitrate and nitrite ions in the PAW could be the main reason for the increase in plant growth. Soaking seeds in PAW not only serves as an anti-bacterial but also enhances the seed germination and plant growth. PAW could potentially be used to increase crop yield and to fight against the drought stress environmental conditions.

Plasma activated water (PAW): Chemistry, physico-chemical properties, applications in food and agriculture

The details of all steps involved in the quantification of
biofilm formation in microtiter plates are described. The
presented protocol incorporates information on assessment of
biofilm production by staphylococci, gained both by direct
experience as well as by analysis of methods for assaying
biofilm production. The obtained results should simplify
quantification of biofilm formation in microtiter plates, and
make it more reliable and comparable among different
laboratories.

Quantification of biofilm in microtiter plates: overview oftesting conditions and practical recommendations for assessmentof biofilm production by staphylococci.

Plasma agriculture: A rapidly emerging field

Reactive nitrogen species in plasma-activated water: generation, chemistry and application in agriculture

Summary Light-induced germination of Paulownia tomentosa seeds was used as an experimental system to investigate the effect of pretreatments by non-equilibrium (low temperature) air plasma on the germination process. Dry P. tomentosa seeds exposed to the plasma changed their germination characteristics. Non-equilibrium plasma treatments significantly increased the light sensitivity of P. tomentosa seeds. These treatments could not substitute for the light-requirements of the seeds. After a short exposure to plasma (4 to 6 minutes) treated seeds had a germination of 75%, i.e. significantly higher than the 5-30% for seeds which did not undergo pretreatment. The results suggest that the stimulatory effect of the non-equilibrium air plasma pretreatment is not a direct photoreceptor-mediated phenomenon. Possible mechanisms of this effect are discussed.

The stimulatory effect of non-equilibrium (low temperature) air plasma pretreatment on light-induced germination of Paulownia tomentosa seeds

The 2022 Roadmap is the next update in the series of Plasma Roadmaps published by Journal of Physics D with the intent to identify important outstanding challenges in the field of low-temperature plasma (LTP) physics and technology. The format of the Roadmap is the same as the previous Roadmaps representing the visions of 41 leading experts representing 21 countries and five continents in the various sub-fields of LTP science and technology. In recognition of the evolution in the field, several new topics have been introduced or given more prominence. These new topics and emphasis highlight increased interests in plasma-enabled additive manufacturing, soft materials, electrification of chemical conversions, plasma propulsion, extreme plasma regimes, plasmas in hypersonics, data-driven plasma science and technology and the contribution of LTP to combat COVID-19. In the last few decades, LTP science and technology has made a tremendously positive impact on our society. It is our hope that this roadmap will help continue this excellent track record over the next 5–10 years.

The 2022 Plasma Roadmap: low temperature plasma science and technology

We study development of plasma packages in atmospheric pressure plasma jet from their formation as a discharge close to the instantaneous cathode, following their motion between and inside the electrodes up to their emergence at the edge of the glass tube and formation of a plasma bullet. Inside both electrodes, plasma is concentrated close to the walls and is bright, while outside it is located at the axis. This paper opens issues of the geometry of electrodes, fields, and atomic processes, allowing some predictions to be made about pertinent mechanisms.

Nevena Puač

Papers

Plasma agriculture: A rapidly emerging field

Reactive nitrogen species in plasma-activated water: generation, chemistry and application in agriculture

The stimulatory effect of non-equilibrium (low temperature) air plasma pretreatment on light-induced germination of Paulownia tomentosa seeds

The 2022 Plasma Roadmap: low temperature plasma science and technology

Time resolved optical emission images of an atmospheric pressure plasma jet with transparent electrodes