Plasma medicine has successfully made the transition to therapeutic applications of cold atmospheric plasma (CAP) in the field of wound healing, and plasma-assisted cancer treatment has become the next promising area of application to be researched. Consequently, further areas of application are to be developed in the future. Due to CAP's well-known antimicrobial and antiviral effectiveness, its anti-infective potential can also be exploited for therapeutic purposes. Driven by the SARS-CoV-2 pandemic, the upper respiratory tract became the focus of interest as a possible site for local CAP application. The paper gives an overview of the interdisciplinary approach to developing this new field of application and presents preliminary results on the local antiviral CAP application in the oropharyngeal region.
Acute wounds require a rapid and effective healing process to prevent complications and prolonged tissue damage. Recently, medical plasma technology has been increasingly investigated as a non-invasive approach to accelerate wound healing through modulation of the wound microenvironment. This study aimed to evaluate the effects of contact and non-contact medical plasma (NCPA) therapy on acute wound healing using macroscopic and histopathological assessments. Argon gas with a purity of 99.995% was used as the carrier gas to generate the plasma jet at a flow rate of 1 standard liter per minute (slm). A total of 32 male Balb/c mice weighing 30-35 g were used in this study. A 4-mm diameter wound was created on the dorsal area of each mouse. The experiment was divided into four treatment groups: K (acute wounds without plasma therapy), CPA (contact plasma at a 5 mm distance), NCPA (at a 20 mm distance), and CP-NCPA (a combination of contact and NCPA). Wound healing progression was evaluated macroscopically by analyzing changes in the wound area ratio during the healing period relative to the initial wound area, while microscopic evaluation focused on re-epithelialization through histopathological examination. The results demonstrated that NCPA therapy administered from day 0 after wound induction (D0) to D7 resulted in a more rapid reduction in wound area ratio compared with the control group. Furthermore, during the period from D8 to D14, the NCPA group consistently exhibited the lowest wound area curve accompanied by a significant increase in re-epithelialization. These findings indicate that NCPA irradiation effectively accelerates wound contraction and enhances epithelial regeneration during the proliferative to remodeling phases. In conclusion, NCPA therapy effectively reduces wound area and consistently enhances re-epithelialization, and therefore is recommended as a promising non-invasive approach for accelerating acute wound management.
Tooth bleaching is a common aesthetic dental procedure, traditionally performed using hydrogen peroxide (H2O2). With the growing use of dental prosthetic materials, their discoloration and aesthetic maintenance have become increasingly important. However, conventional bleaching methods may be ineffective or may compromise their surface properties. This study evaluates the bleaching efficacy of cold atmospheric plasma (CAP) on stained computer-aided design/computer-aided manufacturing (CAD/CAM) prosthetic materials: CEREC (a feldspathic glass ceramic) and Cerasmart (a nanohybrid ceramic in a resin matrix). Samples were stained with coffee to simulate clinical discoloration. Optimization studies identified 10 min as the optimal CAP exposure time. Three bleaching protocols were tested: 35% H2O2 alone, CAP alone, and CAP co-activated with 35% H2O2. Results showed that CAP alone achieved comparable bleaching to the combined method for Cerasmart, while CEREC showed slightly better results with the combined treatment. CAP treatment also reduced restaining compared with H2O2 alone. CAP pretreatment had a preventive effect against discoloration, particularly Cerasmart. Surface analyses revealed minimal roughness changes in Cerasmart, whereas CEREC showed increased roughness. Bacterial adhesion was not adversely affected by CAP. Overall, CAP presents a promising alternative to conventional bleaching methods, offering effective whitening with minimal impact on surface properties and microbial behavior.
Materials with dual functionality arising from spatial asymmetry have emerged as a powerful platform for multifunctional surface design. Known as Janus structures, these materials have distinct properties on opposite sides due to their asymmetric configuration, enabling them to perform multiple functions simultaneously. Janus structures formed by plasma-reduced silver (Ag) on oxide matrices are particularly compelling because of their tunable chemical, optical, and biomedical properties. This review explores the synthesis of Ag/oxide structures, fabrication strategies, and biomedical applications, with a focus on plasma-based reduction techniques as a green, fast, dry, and precise approach for fabricating asymmetric Ag domains. Discussions on different applications such as antimicrobial surfaces, wound healing materials, biosensing and diagnostics, drug delivery platforms, and tissue engineering and implants are presented. Ongoing research has focused on enhancing the scalability, stability, and multifunctionality of Ag/oxide materials, further broadening their scope for future biomedical technologies. Through this review, the aim is to position plasma-reduced Ag/oxide structures as a versatile and sustainable platform for the next generation of responsive and multifunctional biomedical interfaces.
In this paper, we present a detailed study of the experimental measurements of the electrical and optical characteristics in dielectrics barriers discharge (DBD) operating with of a 50% neon-xenon gas mixture for excimer lamp applications. The DBD discharge is excited by a sinusoidal applied voltage for two types of DBD lamps: lamp A (30 × 30 cm) and lamp B (60 × 60 cm), under different values of gas pressures and at a fixed frequency of 20 kHz. The objective of this study is to achieve a uniform light source by optimizing the operating conditions and discharge parameters for maximum luminous efficiency. The temporal evolution of electrical properties of plasma was measured with an oscilloscope, combined with a voltage probe and a current probe. In addition, an optical investigation focusing on luminance and luminous efficacy was carried out to characterize the flat DBD lamp filled with a neon-xenon gas mixture. The results clearly show that DBD lamp B (60 × 60 cm), operated at a gas pressure of 500 mbar, has a better and improved luminous uniformity than DBD lamp A (30 × 30 cm) excited with a sinusoidal voltage waveform.
Microbiological contamination of surfaces is a significant issue across various sectors, posing a serious risk of pathogen transmission between individuals and impacting public health. Among the available decontamination methods, ultraviolet-C (UVC) radiation has seen a surge in popularity in recent years, particularly following the COVID-19 pandemic. However, concerns have been raised regarding the environmental impact and the risk for users of mercury-containing UVC devices. Despite their well-documented biocidal efficacy against a broad spectrum of microorganisms, UVC radiation can be significantly hindered by the presence of organic matter, biofilms, or surface irregularities that create shadowed areas. In this study, we present an innovative approach that combines a krypton-chlorine (KrCl) excimer lamp with a UVC phosphor. Optical characterization techniques - including optical emission spectroscopy, camera imaging, and irradiance measurements - were used to analyze the KrCl lamp and two lamp-phosphor combinations, revealing the complementary nature of these two UVC sources. This synergy was further investigated and validated against two bacterial species (Escherichia coli and Staphylococcus aureus) and the HAdV5 adenovirus. The promising results highlight new opportunities for enhancing UVC-based surface decontamination strategies by combining UVC radiation sources.
This study compares the effects of 10% ascorbic acid (AA), Er:YAG laser (LA), and non-thermal atmospheric nitrogen plasma (NANP) on the micro-shear bond strength (μSBS) of post-bleaching composite restorations. Fifty third molars (wisdom teeth) were allocated into five groups (n = 10): negative control (NC) (bonding/restoration without bleaching), positive control (PC) (bleaching followed by bonding/restoration), AA (bleaching followed by 10% AA for 10 min), LA (bleaching followed by Er:YAG laser irradiation at 20 Hz, 2 W, for 1 min), and NANP (bleaching followed by NANP at 70 W and 3000 cc/min for 1 min). Bleaching was done using 35% hydrogen peroxide gel. μSBS was evaluated using a universal testing machine, with one-way ANOVA and Tukey's post-hoc serving for analysis (α = 0.05). The NANP group achieved the highest μSBS (37.5 ± 8.0 MPa), surpassing all other groups. The PC group had the lowest bond strength (7.5 ± 4.4 MPa). NC group values (18.7 ± 3.7 MPa) were higher than those of LA and AA (MD = 1.2 MPa, P < 0.001, and MD = 6.3 MPa, P < 0.001, respectively), with no differences between LA and AA (MD = 5.1 MPa, P = 0.20). NANP significantly enhanced immediate bond strength after bleaching, surpassing even pre-bleaching levels. While LA and AA treatments also mitigated bleaching effects, they performed weaker in comparison, with no difference in their efficacy. NANP's superior performance suggests its potential to improve same-day restorative outcomes post-bleaching. Further studies and clinical validation are needed to refine this method's protocols and ensure long-term bond stability.
Cold atmospheric pressure plasma's applications are gaining interest in the biomedical and industrial fields. In particular, atmospheric pressure surface dielectric barrier discharge (SDBD) plasma constitutes a promising approach for the decontamination of large and sensitive substrates that require non-contact plasma treatment, as their process mostly relies on the transfer of plasma-generated reactive species, such as ozone, to the treatment samples. In this context, numerical modeling of plasmas can represent a valuable tool to enhance the understanding of the fundamental mechanisms promoting the process. As some detailed models, such as self-consistent fluid models, would accurately simulate the ozone transport to the substrate, these often require significant computing power and high execution times. Multizone global modeling of plasmas might represent a valid alternative to consider detailed chemical mechanisms while including approximated mechanisms for the transport of species from the plasma to the gas phase. In this work, the ozone concentration predicted by a multizone global model is compared with experimental measurements in order to characterise and understand the influence of species transport on the simulation results.
Among emerging biomedical approaches, dielectric barrier discharge (DBD) plasma has shown promise in accelerating wound healing and enhancing sterilization through the production of reactive oxygen and nitrogen species (RONS), which drive tissue regeneration. Recent studies underscore oxygen as a critical factor in radical generation at wound sites, influencing various stages of tissue repair. Consequently, monitoring oxygen concentration and plasma temperature is essential, as both hypoxic and hyperoxic conditions can impede healing. Building on oxygen's critical role in tissue repair, a helium-based plasma sheet was developed to treat large wound areas more efficiently than conventional plasma jets. Two-photon absorption laser-induced fluorescence (TALIF) was employed to evaluate how varying plasma input parameters affect the relative concentration of atomic oxygen in helium plasma. Results show that 0.1 slpm oxygen added to helium plasma increased atomic oxygen fourfold as voltage doubled compared to helium-only plasma. Optical emission spectroscopy with SPECAIR modeling was used to estimate plasma temperature components as oxygen was added to the helium plasma to confirm that plasma still retained its nonequilibrium (Te ∼ Tv > Tr ∼ Tt). The antimicrobial efficacy of plasma was evaluated by exposing Escherichia coli K-12 colonies to helium-oxygen plasma, achieving an ∼ 82% reduction in bacterial levels with 0.1 slpm added oxygen. Overall, this work demonstrates a promising pathway to optimize wound healing using nonthermal plasma technologies.
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.
When atmospheric-pressure plasmas (APPs) are applied to living mammalian cells, which typically coexist with saline, the cells may be exposed to various bactericidal agents, including hydrogen peroxide (H2O2), generated by the plasmas, and possibly protected from bacterial infections. However, an earlier study demonstrated that H2O2 was decomposed in a phosphate-buffered saline (PBS) solution exposed to APPs. In other words, the bactericidal effect of H2O2 may be mitigated under such conditions. The decomposition was attributed to the liquid-phase reaction between H2O2 and hypochlorite anion (ClO-). A more recent study has also shown, using global simulations of a liquid-phase chemical reaction model, that chlorine monoxide ClO, rather than ClO- , decomposes H2O2 more efficiently in a PBS solution exposed to APPs, although the generation of ClO is required for the presence of ClO- . A question, however, remained as to whether the H2O2 decomposition by ClO occurs only near the solution surface or in the solution bulk because a global simulation cannot distinguish the location of chemical reactions inside a solution. The present study is motivated to provide a better understanding of the H2O2 decomposition mechanism. The present study has demonstrated, using one-dimensional numerical simulations, that the reaction between H2O2 and ClO is indeed the dominant decomposition pathway for H2O2 even in the presence of diffusion of chemical species into the solution bulk, and the location of the dominant H2O2 decomposition reaction is not limited to the solution surface region; it can also occur in the bulk of the PBS solution.
The cold atmospheric pressure plasma jet (CAPPJ) has emerged as a promising tool for biomedical applications, particularly in wound healing and infection control. This study investigates an argon-based CAPPJ generated at an applied voltage of 3.5 kV and a frequency of 20 kHz, assessing its physical and chemical properties and its therapeutic effects on diabetic wound healing. The plasma jet was characterized using optical emission spectroscopy (OES) to determine electron excitation temperature (Texc) while current-voltage waveform analysis provided insights into discharge dynamics. The plume temperature, measured using a laser infrared thermometer, ranged between 18.5°C and 30°C, ensuring suitability for biological applications. Diabetic wounds were induced in rat models through alloxan monohydrate administration, and CAPPJ treatment was applied at varying exposure times. Results demonstrated enhanced cellular proliferation, with multiple 2-min treatments showing optimal wound healing outcomes. The antibacterial effect of plasma, attributed to reactive oxygen and nitrogen species (RONS), played a key role in preventing wound progression to chronic stages. These findings highlight the potential of CAPPJ as an effective non-invasive therapeutic approach for managing diabetic wounds. Further investigations into optimized treatment parameters and long-term biological responses are warranted to enhance its clinical applicability.
