Emergence and spread of antibiotic resistance calls for development of non-chemical treatment options for bacterial infections. Plasma medicine applies low-temperature plasma (LTP) physics to address biomedical problems such as wound healing and tumor suppression. LTP has also been used for surface disinfection. However, there is still much to be learned regarding the effectiveness of LTP on bacteria in suspension in liquids, and especially on porous surfaces. We investigated the efficacy of LTP treatments against bacteria using an atmospheric-pressure plasma jet and show that LTP treatments have the ability to inhibit both gram-positive (S. aureus) and gram-negative (E. coli) bacteria on solid and porous surfaces. Additionally, both direct LTP treatment and plasma-activated media were effective against the bacteria suspended in liquid culture. Our data indicate that reactive oxygen species are the key mediators of the bactericidal effects of LTP and hydrogen peroxide is necessary but not sufficient for antibacterial effects. In addition, our data suggests that bacteria exposed to LTP do not develop resistance to further treatment with LTP. These findings suggest that this novel atmospheric-pressure plasma jet could be used as a potential alternative to antibiotic treatments in vivo.

Plasma medicine is an emerging field that applies the science and engineering of physical plasma to biomedical applications. Low-temperature plasma, also known as cold plasma, is generated via the ionization of atoms in a gas, generally via exposure to strong electric fields, and consists of ions, free radicals, and molecules at varying energy states. Plasmas generated at low temperatures (approximately room temperature) have been used for applications in dermatology, oncology, and anti-microbial strategies. Despite current and ongoing clinical use, the exact mechanisms of action and the full range of effects of cold plasma treatment on cells are only just beginning to be understood. Direct and indirect effects of plasma on immune cells have the potential to be utilized for various applications such as immunomodulation, anti-infective therapies, and regulating inflammation. In this review, we combine diverse expertise in the fields of plasma chemistry, device design, and immunobiology to cover the history and current state of plasma medicine, basic plasma chemistry and their implications, the effects of cold atmospheric plasma on host cells with their potential immunological consequences, future directions, and the outlook and recommendations for plasma medicine.

C₂⁺ hydrocarbons are selectively produced in one-step catalytic CO₂ conversion via designing the catalyst-bed configuration under non-thermal DBD plasma operating at low temperature and atmospheric pressure.

The liquid-phase behavior induced by an atmospheric pressure plasma jet impinging onto water-based solutions was experimentally investigated. An increase in cavity size and circulation size resulting from an increase in impact force of the plasma jet with respect to a helium gas jet were observed through particle image velocimetry and cavity measurements. The increase in circulation size due to plasma discharge was larger than the increase solely due to an increase in jet impact force, suggesting additional shear along the liquid free surface evidenced by schlieren images of plasma-induced gas flow adherence after impingement. Liquid evaporation rate increased and mean liquid temperature decreased due to plasma effects on jet behavior. Plasma-induced decreases in liquid pH and temperature were contained within the circulation flow, leading to strong pH and temperature gradients within the liquid volume. Areas treated by the jet became acidic and remained more acidic than other portions of the liquid due to circulation vortices, highlighting the consequences of jet and liquid vessel parameters for plasma jet-liquid applications.