Tracking the Penetration of Plasma Reactive Species in Tissue Models

Electrically generated cold atmospheric plasma is being intensively researched for novel applications in biology and medicine. Significant attention is being given to reactive oxygen and nitrogen species (RONS), initially generated upon plasma-air interactions, and subsequently delivered to biological systems. Effects of plasma exposure are observed to millimeter depths within tissue. However, the exact nature of the initial plasma-tissue interactions remains unknown, including RONS speciation and delivery depth, or how plasma-derived RONS intervene in biological processes. Herein, we focus on current research using tissue and cell models to learn more about the plasma delivery of RONS into biological environments. We argue that this research is vital in underpinning the knowledge required to realize the full potential of plasma in biology and medicine. Physical effects of plasma can be seen to depths of several hundred micrometers within tissue.Plasma-derived RONS are likely to be delivered millimeters into tissues.Speciation reveals that RONS delivered by plasma into tissue fluid and tissue are predominately stable secondary RONS - for example, H 2 O 2 , NO 2 - , and NO 3 - .The plasma generation of RONS within a hydrated target is influenced by the target matrix that can enhance or reduce the RONS concentrations and act as a reservoir of RONS.It is likely that the concentration of these plasma-derived RONS exceeds hundreds of micromoles, even at depths of several millimeters within tissue.Oxygen concentration at the time of plasma treatment significantly influences RONS generation within a hydrated proteinaceous target. Refereed/Peer-reviewed