A plasma-treated spray (PTS) system is developed to combine gas-phase plasma and plasma-treated droplets for seed treatment. The modular design enables scalable generation of plasma-treated sprays suitable for large-area applications. The effects on germination are evaluated for five crop species: wheat, barley, pea, onion, and beetroot. Plasma treatment improves germination vigor in wheat, barley, and pea. Onion and beetroot show limited or species-specific responses. Electrical characterization demonstrates linear scalability of discharge energy and power consumption over the number of plasma reactor units. The PTS approach achieves competitive energy efficiency and treatment cost, representing a promising step toward sustainable, field-scale plasma applications in agriculture.

Despite promising in vitro outcomes, the clinical translation of plasma jet technologies remains constrained by the absence of reproducible and standardized evaluation parameters. A major challenge lies in quantifying plasma-induced biochemical changes in a manner that is both biologically relevant and independent of specific devices. In this study, we present a dissolved oxygen (DO)-based photonic parameter obtained through time-resolved phosphorescence spectroscopy as a real-time, reagent-free method for characterizing plasma-activated media. By correlating the maximum change in phosphorescence lifetime—an indirect indicator of minimum DO concentration of the liquid—with metabolic activity across various stem cell types treated by the different plasma jet configurations, we introduce a novel prediction metric for the metabolic activity of stem cells that is both cell-specific and jet-independent. This parameter shows promise as a non-invasive, cell-specific redox response signature, potentially aiding future stem cell classification efforts. Moreover, jet-independent characteristic of the parameter supports more consistent cross-study comparisons, simplifies jet calibration, and advances efforts to standardize plasma jet applications in biomedical research.

This study examined two distinct pulse generators operating with the same reactor, utilizing helium and helium/oxygen mixtures as the working gases. The research focused on the distribution of RONS on the agar surface, their concentration, and the bacterial inhibition halo. The findings demonstrate that modifying the gas mixture influences the concentration of RONS, thereby altering the dominant reactive species and affecting the levels of others during plasma exposure. The incorporation of O 2 into the gas mixture leads to less homogeneous treatment, thereby complicating the eradication of microbes. Nevertheless, it also broadens the spectrum of RONS delivery, which may be beneficial for demanding clinical applications, including tracheal T-tube biofilm control, as preliminary investigated in this work.

Cold atmospheric plasma (CAP) has emerged as a promising anticancer approach because of its ability to selectively eliminate malignant cells. Among the proposed mechanisms of this selectivity, the Bauer theory emphasizes the synergistic action of plasma-derived hydrogen peroxide (H2O2) and nitrite (NO2-), leading to the transient generation of primary singlet oxygen (1O2). This early event inactivates membrane-bound catalase, allowing tumor cell-derived H2O2 and peroxynitrite to initiate a self-amplifying cycle that produces secondary 1O2, as a hallmark of CAP selectivity. To test this hypothesis, in this work, we monitored extracellular dissolved oxygen (DO) dynamics in HT-29 colorectal cancer cells treated with an argon plasma jet using time-resolved phosphorescence lifetime spectroscopy. Temporal variations in DO likely reflect the cumulative effect of rapid 1O2 production and its reactions with cells. A delayed surge in extracellular 1O2 was observed specifically in dying cancer cells within the 10-20 min window predicted by the model. Intracellular ROS imaging confirmed a strong correlation between intracellular ROS, extracellular 1O2 dynamics, and viability loss. Together, these results provide mechanistic validation of Bauer's redox model and suggest that early oxygen dynamics after CAP exposure can serve as predictive markers for treatment efficacy in plasma or photodynamic therapies.

The interaction between nanosecond pulsed discharges and acoustically levitated droplets is investigated using time-resolved ICCD imaging, optical emission spectroscopy (OES), electrical diagnostics, and numerical simulations. Experiments are carried out in a pin-to-pin electrode configuration in air at atmospheric pressure with ultra pure water droplets (1 & micro;S.cm-1) and saline droplets (16 mS.cm-1). The results show that the droplet acts as an obstacle contoured by the plasma channel while enhancing the local electric field through polarization, thereby facilitating plasma ignition. For ultra pure water, two streamers develop between the electrodes and the droplet and subsequently merge into a single plasma channel enveloping the droplet surface after approximately 2 ns. In contrast, for saline droplets, electron neutralization at the liquid interface slows streamer propagation along the surface, delaying the merging process. After about 10 ns, however, the discharge evolution becomes similar for both droplet types, regardless of conductivity. The droplet behaves as a capacitor, with its capacitance governing the charging time and influencing early streamer dynamics. Finite element numerical simulations confirm the electric field enhancement near the droplet poles, while evaporation measurements indicate negligible plasma-induced heating, excluding significant Joule effect. Overall, these findings advance the understanding of plasma-droplet interactions and highlight the decisive role of liquid conductivity and dielectric properties in discharge dynamics. The insights gained provide a foundation for optimizing plasma-liquid processes involving droplets in environmental, biomedical, and material science applications.

Cold atmospheric plasma (CAP) has shown promising potential across biomedical applications. However, translating these effects into predictable and reproducible outcomes remains challenging due to device variability and the complex and unknown interplay of reactive species. This study evaluates the potential of machine learning (ML) to reliably predict CAP biological results including 24 h MTT and 48 h MTT from optical emission spectroscopy (OES) data. Data-driven models correlate plasma characteristics with cell viability and metabolic activity outcomes in human dermal fibroblasts. Diverse ML models were employed for their differing capabilities in feature extraction from OES data, essential for assessing the predictive capability of ML models for the biological effects of CAP from OES data. To evaluate cross plasma-device transferability without information leakage, models were tested on two distinct CAP jet systems. While the models achieved high accuracy for the primary jet used in training, their performance degraded considerably when applied to data from the secondary jet. To assess whether the loss of cross-device predictability could in principle be restored through minimal domain calibration, we conducted a controlled fine-tuning ablation on the pre-trained models. Results show that while spectra cannot serve as a device-independent predictor for the acute (24 h MTT) outcome, they retain partial transferability for the delayed (48 h MTT) response when minimal calibration is performed and sufficiently expressive models are employed to extract the underlying transferable structure. Moreover, the analysis identified the plasma source frequency as the most influential operational predictor, followed by voltage and treatment time. In identifying the gas-phase free radicals with the highest impact on biological outcomes, spectral fingerprints show the most influential species contributed in cell viability.

Chemotherapy-induced testicular damage is a major cause of male infertility, primarily due to oxidative stress, apoptosis, and disruption of the spermatogonial niche. Spermatogonial stem cells (SSCs) as well as Sertoli cells are central regulators of spermatogenesis, and preserving their function is essential for maintaining male fertility. This study investigated the protective and regenerative potential of helium plasma-activated conditioned medium (PACM) against bleomycin-induced cytotoxicity in a neonatal rat SSCs-Sertoli cell co-culture model. Testicular cells were isolated and characterized using alkaline phosphatase assay and qRT-PCR for evaluating CD49f and Sox9 expression. Cells were treated with conditioned medium (CM), plasma-activated medium (PAM), and plasma-activated conditioned medium (PACM), either alone or in combination with bleomycin (Ble). Among all treatments, PACM exerted the strongest protective effects, significantly through enhancing cell viability and colony formation as well as reducing intracellular reactive oxygen species (ROS) and apoptosis. Based on findings, Ble markedly disrupted redox balance, apoptosis increment verified through Annexin-FITC externalization, suppressed Nrf2, c-KIT and CAT expression, attenuated catalase enzyme activity; however, co-treatment with PACM most effectively overwhelmed Ble insult, indicating activation of antioxidant defenses and spermatogenic signaling pathways. The superior efficacy of PACM appears to result from the synergistic interaction between plasma-generated reactive oxygen and nitrogen species (RONS) and the bioactive components of conditioned medium, including growth factors, cytokines, and exosomes. Collectively, these findings indicated that PACM restores the spermatogonial microenvironment, reinforces endogenous regenerative capacity, and offers a promising cell-free strategy to mitigate bleomycin-induced reproductive toxicity in vitro. It proposes that future studies are critical to identify the specific PACM components, the principal mediators and signaling pathways responsible for PACM effects. A graphical overview of the experimental workflow and outcomes is presented in Fig. 1.

Actinic keratosis (AK) and squamous cell carcinoma (SCC) represent progressive keratinocyte disorders in which oxidative stress and dysregulated signaling contribute to disease pathology. Medical gas plasma is an emerging therapeutic tool that generates reactive oxygen and nitrogen species capable of modulating cellular function. Here, we evaluated a newly developed helium multijet plasma device for its potential to treat precancerous and cancerous keratinocyte diseases. To cover the entire keratinocyte carcinogenesis process, in vitro models of normal keratinocytes (HaCaT), AK (HT-297.T), and SCC (A431) were used. A 2-minute plasma treatment produced moderate levels of reactive species in the liquid phase, inducing intracellular oxidation and decreasing viability in a cell type-dependent manner, being most effective in SCC. Plasma exposure modulated stress- and survival-associated signaling pathways and reshaped the secretion of growth factors and pro-inflammatory chemokines, with AK cells showing the most pronounced responses. These findings demonstrate that plasma-generated oxidants act as signaling mediators that can fine-tune keratinocyte behavior without overt cytotoxicity in vitro, supporting the potential of controlled plasma exposure as a therapeutic strategy for actinic keratosis and other skin cancers.

Cold atmospheric plasmas (CAPs) have emerged as the central component to plasma medicine, a relatively new research field in which CAPs have shown promise for a variety of biomedical uses and medical therapies. CAPs comprise of a partially-ionized gas that exists at near room temperature and atmospheric pressure. CAPs affect biological materials via chemical, thermal, and electrical interactions that are observable using common plasma characterization measurements. For cases in which the to-be-characterized interface is already exposed (e.g., early skin cancer detection), we propose CAPs can be used for real-time tissue identification in a non-invasive manner. We leverage the sensitivity of CAP interactions with biological interfaces to identify and differentiate biological tissues by using real-time chemical (via optical emission spectra) and electrical (via voltage probes along the circuit) measurements. These information-rich measurements have embedded physics knowledge about the plasma chemistry and its interactions with biological tissues. Thus, we incorporate common physics knowledge to extract and analyze such measurements using machine learning. Our proof-of-concept studies demonstrate that biological tissues can be differentiated with up to 99% test accuracy when differentiating four tissue types (i.e., skin, muscle, bone, and fat) of an ex vivo chicken model. The proposed CAP tissue identification and differentiation approach can effectively augment the medical diagnostic toolkit, including in cancer detection, vascular studies, and real-time surgical analysis.

As plasma-treated liquids have many applications in plasma medicine, their cutaneous effects for cosmetic purposes are also considered as an alternative way to treat skin without the electric hazards and limitations correlated with the use of a direct plasma. Our previous work on human skin explants showed increased transdermal diffusion of cosmetic ingredients (caffeine, hyaluronic acid) after direct plasma treatment. Despite this proven efficacy, these protocols still face limitations dealing with toxicity, small treatment areas and uneven surface coverage. To overcome these limitations and broaden the scope of non-thermal-plasma-based technology for skin care, this study presents for the first time the development and assessment of a plasma aerosol device to nebulize plasma-treated liquids on skin models. This work demonstrates how plasma jet and plasma treated aerosol can temporarily enhance permeation in reconstructed human epidermis (RHE), using fluorescein as a probe, under safe plasma delivery conditions. Transepithelial electrical resistance measurements confirm the transient nature of the plasma-induced modulation, suggesting the possibility to control the duration of the enhanced permeation. Overall, the achieved results demonstrate the potential of plasma jet and plasma treated aerosol to safely control diffusion through skin for cosmetic and medical purposes.

This paper provides an overview of past and new experimental studies with kHz helium plasma jets and floating-electrode dielectric barrier discharge (DBD) in the context of biomedical applications with the aim to discuss the interaction of plasma jet with skin tissue models. The key motivation is to summarize and address perspectives on the understanding of the mode of action of nonthermal plasma from surface delivery to the biological response of deeper and deeper tissues. First, the significant impact of the target exposed to the plasma jet on the plasma characteristics is documented, highlighting the importance of considering this interaction for in vivo studies. Next, cell permeabilization was first reported and translated to the study of plasma jet permeation of reconstructed epidermis, human explants, and human tissues. Strong analogies are observed in all three substrates, demonstrating a potent but transient modulation of surface features and skin barrier function for a few minutes following a brief plasma exposure time of a few tens of seconds. Interestingly, the modulation of reactive oxygen and nitrogen species generation, so-called RONS, with the variation of the pulse repetition rate of the plasma jet shows no direct correlation with the permeation efficiency. This questions the role of RONS alone in the mode of action of nonthermal plasma for biological response in the few hundreds of microns to the few millimeter tissue layers as was previously also questioned for subcutaneous action of plasma in wound and tumor in vivo treatments. Finally, the combinative role of RONS with electrical factors (charging, current, electric field) is hypothesized and supported with the investigation of deeper living skin tissue oxygenation and vasodilation.

This paper evaluates the effect of a microsecond pulsed plasma (MPP) on the stabilization and emission characteristics of non-premixed biogas/air flames with various CO2 contents. The MPP is generated by a unique DC-pulsed power generator providing high voltage (HV) pulses over a wide range of pulse repetition frequencies (PRFs). The burner configuration is made up of two concentric tubes in which a swirler is placed inside the annular part, ensuring the oxidizer's rotation. The central tube delivers the fuel through an injector placed close to the burner exit. Electrical diagnostics, including voltage, were performed. OH* chemiluminescence measurements were done to describe the structure and stability of the flame. Results showed that plasma generated by microsecond HV pulses can improve flame stability. In this regard, the distribution of key active species in the burner was studied via optical emission spectroscopy (OES). The results revealed that the pulsed plasma generates chemically active species such as excited N2*, CH*, OH* molecules, and H* and O* atoms, thereby improving flame stability. The dependence of the emitted species intensities on plasma parameters was investigated in detail. It is demonstrated that MPP can drastically enhance the dynamic flame stability of swirling non-premixed biogas flames, especially at lean operating conditions. In addition, NOx and CO emissions were studied over a wide range of pulse repetition frequencies. It is seen that the pulsed plasma increases NOx emission slightly and significantly reduces CO concentration in the flue gases.

Cold atmospheric pressure plasma (ionized gas) is an innovative medical tool for the treatment of infected wounds thanks to its potential to inactivate drug-resistant microorganisms and promote tissue regeneration and vascularization. The low power consumption, compactness, and versatility of Cold Atmospheric Pressure Plasma (CAPP) devices make them an ideal tool for risk mitigation associated with human spaceflights. This work presents results in microgravity on the operability of CAPP and its antimicrobial effect. The experiments carried out in parabolic flights make it possible to optimize the treatment conditions (i.e., the distance, the gas mixture) and to obtain the rapid inactivation (<15 s) of Escherichia coli samples. Interestingly, the inactivation efficiency of CAPP was higher during parabolic flights than under terrestrial conditions. Overall, these results encourage the further development of CAPP medical devices for its implementation during human spaceflights.

Besides many efforts on the detection and quantification of reactive oxygen and nitrogen species (RONSs) in the aqueous media activated by the cold atmospheric plasma, to get a better insight into the dominant mechanism and reactive species in medical applications, a challenge still remains in monitoring the real-time evaluation of them. To this end, in the present work, relying on the photonic technology based on the time-resolved phosphorescence spectroscopy, real-time tracking of RONSs concentration in treated aqueous media is achieved by following the dissolved oxygen (DO) production/consumption. Using a photonic-based dissolved oxygen sensor, the dependence of real-time RONS concentration evaluation of plasma activated medium on plasma nozzle distance, non-thermal plasma jet exposure time, various culture media, and presence of cells is investigated. Analyzing the results, the activation parameters including the time of reaching maximum RONS concentration after treatment and defined activation parameter [Formula: see text] of the treated media for each case is measured and compared together. Moreover, employing the scavengers related to two involved ROSs, the dominant chemical reactions as well as ROS contributed in the DMEM medium is determined. As a promising result, the obtained correlation between the real-time DO level and viability and toxicity of the cancer cells, MCF-7 breast cancer cells, could enable us to exploit the present photonic setup as an alternative technique for the biological assessment.

There is a huge gap between the output and demand of soybean in China. How to improve the seed vigor of soybean has always been a research focus. Low temperature plasma (LTP) is a new green technology, which is widely used in crop seed treatment. Corona plasma is a typical discharge mode of plasma, which can affect the vigor of seeds. The effect of different discharge power on the soybean seed vigor by plasma treatment was experimentally investigated. Plasma discharge characteristic wavelength and spatial distribution were analysed. It shows that the corona discharge spectrum mainly exhibits the strong ultraviolet radiation and 90% of the spectral intensity focused in the center of discharge region. Water absorption and germination index of seeds and the fresh weight of seedlings were used to characterize the specific effects caused by different plasma powers. The results show that plasma treatment has a significant effect on the early stage of germination and can significantly affect the soybean seed vigor and growth. Overdose treatment will cause inhibiting effect. This study provides an experimental basis for the practical agriculture application of corona plasma seed treatment.

Plasma sources suitable to generate low temperature plasmas has been fundamental for the advances in plasma medicine. In this research field, plasma sources must comply with stringent conditions for clinical applications. The main requirement to be met is the patient and operator's safety and the ethical requirement of effectivity, which encompasses the electrical regulations, potential device toxicity and effectiveness in relation to the desired treatment. All these issues are addressed by the German pre-standard DIN SPEC 91315:2014-06 (DINSpec), which deals with the safety limits, risk assessment and biological efficacy of plasma sources aimed for medical applications. In this work, a low cost, user-friendly and flexible atmospheric pressure plasma jet (APPJ) device was characterized following the DINSpec guidelines. The device, which is still under development, proved to be safe for medical applications. It is capable of producing an APPJ with low patient leakage current and UV emission, gas temperature lower than 40 {\deg}C, production of harmful gases within the safety limits and low cytotoxicity. The most differentiating feature is that the device presented good antimicrobial efficacy even operating at frequency of the order of just a few hundred Hz, a value below that of most devices reported in the literature.

This work focuses on the antimycotic effects of the plasma gun as a potential tool for the treatment of superficial infections. Candida glabrata was chosen as a model microorganism. The preliminary tests have been done on the agar plates to establish the basic plasma parameters. To render this research more appropriate to the real application, more complex inoculation substrates, pork skin and 3D-printed models of the dog ear canal have been used. The results of this work confirm the high efficiency of cold plasma in the inhibition of yeasts on different surfaces and will lead to further experiments.