UC Berkeley

Treatment of biological tissue by non-thermal atmospheric pressure plasmas in air can often cause beneficial biological outcomes, commonly by generation and delivery of reactive oxygen and nitrogen species (RONS). Biological plasma treatment is often mediated through plasma-liquid interactions, wherein plasma-generated RONS are dissolved into the liquid phase and subsequently initiate liquid-phase chemistry. In this paper we report observations on plasma-liquid interactions using a biologically inert perfluorocarbon solvent - perfluorodecalin (PFD) - that is known to be useful in other biomedical applications. The present paper concerns thin films of liquid PFD applied to porous and non-porous surfaces and subsequent plasma exposure of these films. With PFD application as a thin film prior to plasma exposure, we observe evidence of delayed, but ultimately enhanced RONS delivery to non-porous surfaces and through porous underlying surfaces. We demonstrate that PFD dissolves and retains relatively high concentrations of plasma-produced RONS, especially NO2. When the thin liquid film of PFD evaporates during plasma exposure, there appears to be a relatively rapid release of dissolved RONS, potentially aiding certain applications.