Diffusive plasma jet vs. conventional linear plasma jets: physical properties, chemical production, in vitro effects on cell proliferation and collagen production

Cold atmospheric plasma jets show promising results in chronic wound healing. In this study, three AC kHz helium plasma jet configurations are characterized: two standard linear plasma jets and an innovative large area diffusive jet. The latter consists of a linear tube with an expansion bell closed at its end by sintered glass material generating a 50 mm² uniform plasma. First, three configurations are compared with respect to their physicochemical aspects: the ionization front propagation and interaction with dielectric and liquid target is monitored using an electric field (E-field) probe, and the production of H₂O₂ and NO₂⁻ in liquid target as a function of the energy dose is measured. Second, a preliminary study is conducted on simple biological models in vitro: collagen secretion from primary fibroblasts and proliferation from keratinocytes (HaCaT) are assessed. It results that collagen secretion and cell proliferation are enhanced when treated with the diffusive jet, contrary to linear jets. The diffusive jet produces higher E-field and lower concentration of H₂O₂ and NO₂⁻ compared to standard linear jets. This suggests that the balance between E-field and reactive oxygen and nitrogen species is critical to stimulate cell responses.