The project aims to gain further insight into the chemical and physical impacts of two different non-thermal atmospheric pressure plasmas (APP) sources on liquids and biological systems, with an emphasis on applications of APPs in wound healing. The effects of APPs on biological systems are largely driven by the production of a range of reactive oxygen and nitrogen species (RONS). In particular, NO is known to be an important trigger species for wound healing and can be produced in high concentrations in APPs when N₂ and O₂ are present.

In addition, NO derivatives (NODs) such as nitrate, nitrite, and s-nitroso proteins are thought to play key roles. Water-vapour derived RONS, such as OH or H₂O₂ are also thought to be important drivers of plasma-related effects.

In this context, the PlasNOW project is focussed on defining the paths of reactive species, with an emphasis on NO, from the gas to the liquid phase, and the influence of these reactive species on biomolecules, under a variety of different plasma operating parameters. To study these processes, two complementary plasma sources are studied: a volume dielectric barrier discharge (VDBD) and a micro atmospheric pressure plasma jet (μAPPJ). These two devices combined cover a range of operating parameters, for example, direct vs. indirect treatment and operation in air vs. in controlled (noble) gas mixture. We limit the parameter range to answer the following research questions:

• How do the concentrations of NO and NODs from the plasma source to the liquid to the final target i.e. the biomolecule change and develop? What is the process chain?
• How does the NO generation in the plasma influence the flux to the target? What is the impact of the humidity on the production or loss of NO and NODs?
• How do environmental parameters, such as humidity or liquid composition, influence these processes?
• By tuning gas mixture and external electric parameters, to which extent can the production of NO(D) and OH be optimized for both plasma devices?

To answer these questions, the outputs of both devices will be measured in cooperation with our project partners within a shared customized vessel that allows the operation of both devices in variable, controlled atmospheres. To overcome the well-known difficulties of measuring at the liquid / gas interface and within the liquid, a combination of approaches is used. This incorporates optical and laser-based diagnostics in the gas and liquid phase, chemical analysis of plasma-treated biomolecules and numerical simulations. These are carried out in cooperation with project partners within the RUB i.e. the Research Group for Plasma Interface Physics (Jun.- Prof Dr. Judith Golda), the Chair of Inorganic Chemistry I (Prof. Dr. Nils Metzler Nolte) and at the Universitätsklinikum Düsseldorf (Prof. Dr. Christoph Suschek).