Atmospheric pressure plasmas: generation and delivery of reactive oxygen species for biomedical applications

Reactive oxygen species (ROS) that can trigger biological responses are readily attainable in atmospheric pressure plasma sources. Admixtures of oxygen and water can act as precursors for the generation of these ROS and lead to the production of O, OH, O3, 1 O2, OOH and H2O2. The dynamics and chemistry in these discharges is complex and result in intricate spatiotemporal profiles of the species that cannot be accurately captured by zero dimensional analysis. Besides fluxes of neutral ROS, ionic fluxes including anions are also observed. The high reactivity of most of the ROS, however, limits their penetration into the treated sample and therefore encapsulation of the ROS and/or triggering of a secondary chemistry is required for the plasma treatment to reach beyond the first layers of biomolecules.