Cold atmospheric plasma and plasma‑treated saline in the inactivation of <i>Staphylococcus aureus</i> biofilms: structural and physicochemical insights from multimodal analyses

biofilms were exposed to Argon CAP, and morphological and metabolic changes were evaluated using confocal laser scanning microscopy, field emission scanning electron microscopy, Fourier transform infrared spectroscopy, atomic force microscopy, and XTT fluorescence. Planktonic cells were further examined by transmission electron microscopy. The findings revealed significant biofilm disruption with 94% metabolic inactivation after 300 s. To distinguish direct plasma effects, plasma-treated saline was tested and demonstrated to inactivate within 30 min. Optical emission spectroscopy detected intense Na emission (589 nm) during plasma-saline interactions; however, this observation is reported as a spectral feature rather than a mechanistic conclusion, and further experiments are required to clarify its potential relevance.