Applications of Cold Atmospheric Pressure Plasma in Dentistry

Possibilities of Application of Cold Atmospheric Pressure Plasmas in Dentistry—A Narrative Review

According to the World Human Organization (WHO), dental and periodontal diseases are common among the human population. Traditional dentistry offers a wide range of methods for treating oral diseases and performing esthetic procedures. In contrast, cold atmospheric pressure plasma (CAPP) has been found to be a promising technology in multiple fields, particularly in medical sciences such as dentistry. In this study, CAPP might be a promising adjunct to conventional dental treatments. A substantial number of studies have confirmed the effectiveness of both direct and indirect CAPP applications in dentistry. Because CAPP technology is fast, inexpensive, and noninvasive, we aim to review recent literature focused on the application of this methodology in dentistry.

Combining Cold Atmospheric Plasma and Environmental Nanoparticle Removal Device Reduces Neurodegenerative Markers

Ageing leads to a gradual deterioration of the organs, with the brain being particularly susceptible, often leading to neurodegeneration. This process includes well-known changes such as tau hyperphosphorylation and beta-amyloid deposition, which are commonly associated with neurodegenerative diseases but are also present in ageing. These structures are triggered by earlier cellular changes such as energy depletion and impaired protein synthesis, both of which are essential for cell function. These changes may in part be induced by environmental pollution, which has been shown to accelerate these processes. Cold Atmospheric Plasma (CAP) or atmospheric pressure gas discharge plasmas have shown promise in activating the immune system and improving cellular function in vitro, although their effects at the organ level remain poorly understood. Our aim in this work is to investigate the effect of a device that combines CAP treatment with the effective removal of environmental nanoparticles, typical products of pollution, on the activity of aged mouse brains. The results showed an increase in energy capacity, a reduction in reticulum stress and an activation of cellular autophagic clearance, minimising aggresomes in the brain. This leads to a reduction in key markers of neurodegeneration such as tau hyperphosphorylation and beta-amyloid deposition, demonstrating the efficacy of the tested product at the brain level.

Realtime RONS monitoring of cold plasma-activated aqueous media based on time-resolved phosphorescence spectroscopy

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.

Effects of Different No-Ozone Cold Plasma Treatment Methods on Mouse Osteoblast Proliferation and Differentiation

Background and Objectives: Enhanced osteoblast differentiation may be leveraged to prevent and treat bone-related diseases such as osteoporosis. No-ozone cold plasma (NCP) treatment is a promising and safe strategy to enhance osteoblast differentiation. Therefore, this study aimed to determine the effectiveness of direct and indirect NCP treatment methods on osteoblast differentiation. Mouse osteoblastic cells (MC3T3-E1) were treated with NCP using different methods, i.e., no NCP treatment (NT group; control), direct NCP treatment (DT group), direct NCP treatment followed by media replacement (MC group), and indirect treatment with NCP-treated media only (PAM group). Materials and Methods: The MC3T3-E1 cells were subsequently assessed for cell proliferation, alkaline phosphatase (ALP) activity, calcium deposition, and ALP and osteocalcin mRNA expression using real-time polymerase chain reaction. Results: Cell proliferation significantly increased in the NCP-treated groups (DT and PAM; MC and PAM) compared to the NT group after 24 h (p < 0.038) and 48 h (p < 0.000). ALP activity was increased in the DT and PAM groups at 1 week (p < 0.115) and in the DT, MC, and PAM groups at 2 weeks (p < 0.000) compared to the NT group. Calcium deposition was higher in the NCP-treated groups than in NT group at 2 and 3 weeks (p < 0.000). ALP mRNA expression peaked in the MC group at 2 weeks compared to the NP group (p < 0.014). Osteocalcin mRNA expression increased in the MC group at 2 weeks (p < 0.000) and was the highest in the PAM group at 3 weeks (p < 0.000). Thus, the effects of direct (DT and MC) and indirect (PAM) treatment varied, with MC direct treatment showing the most significant impact on osteoblast activity. Conclusions: The MC group exhibited enhanced osteoblast differentiation, indicating that direct NCP treatment followed by media replacement is the most effective method for promoting bone formation.

Effects of different plasma treatments on bonding properties of zirconia

This in vitro study was to evaluate the effect of different non-thermal atmospheric pressure plasma (NTP) on shear bond strength (SBS) between yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) and self-adhesive resin cement. In this study, The Y-TZP specimens were divided into 4 groups according to the surface treatment methods as follows: Control (no surface treatment), Sb (Sandblasting), AP(argon NTP), and CP(20 % oxygen and 80 % argon combination NTP). Y-TZP specimens were randomly selected from each group to observe and test the following indexes: scanning electron microscope to observe the surface morphology; atomic force microscope to detect the surface roughness; contact angle detector to detect the surface contact angle; energy spectrometer to analyze the surface elements. Then, resin cement (Rely X-U200) was bonded to human isolated teeth with Y-TZP specimens to measure SBS. The results showed that for the SE test, the NTP group was significantly higher than the control group (p < 0.05). The results of the SBS test showed that the SBS values of the NTP group were significantly higher than those of the other groups, regardless of the plasma treatment (p < 0.05). However, there was no significant difference between groups AP and CP in a test of SBS (p > 0.05). This study shows that non-thermal atmospheric pressure plasma can improve the shear bond strength of Y-TZP by increasing the surface energy. The addition of oxygen ratio to argon is more favorable to increase the shear bond strength and is worth further investigation.

Anti-Inflammatory Activity of No-Ozone Cold Plasma in Porphyromonas gingivalis Lipopolysaccharide-Induced Periodontitis Rats

Periodontitis is an inflammatory disease caused by Porphyromonas gingivalis (P. gingivalis) in the oral cavity. This periodontal disease causes damage to the periodontal ligament and alveolar bone and can cause tooth loss, but there is no definite treatment yet. In this study, we investigated the possibility of using no-ozone cold plasma to safely treat periodontitis in the oral cavity. First, human gingival fibroblasts (HGFs) were treated with P. gingivalis-derived lipopolysaccharide (PG-LPS) to induce an inflammatory response, and then the anti-inflammatory effect of NCP was examined, and a study was conducted to identify the mechanism of action. Additionally, the anti-inflammatory effect of NCP was verified in rats that developed an inflammatory response similar to periodontitis. When NCP was applied to PG-LPS-treated HGFs, the activities of inflammatory proteins and cytokines were effectively inhibited. It was confirmed that the process of denaturing the medium by charged particles of NCP is essential for the anti-inflammatory effect of NCP. Also, it was confirmed that repeated treatment of periodontitis rats with NCP effectively reduced the inflammatory cells and osteoclast activity. As a result, this study suggests that NCP can be directly helpful in the treatment of periodontitis in the future.

In vitro evaluation of the tooth bleaching efficacy and safety of high-concentration hydrogen peroxide with cold atmospheric plasma

BACKGROUND

Using hydrogen peroxide (HP) for tooth bleaching may induce various side effects. Cold atmospheric plasma (CAP) is a promising solution. We aimed to evaluate and compare the efficacy and safety of tooth bleaching using high-concentration HP with CAP with conventional in-office bleaching.

METHODS

Fifty-one discolored extracted human teeth were assigned to three groups: Group 1 (light-emitting diode with 35 % HP), Group 2 (CAP with 35 % HP), and Group 3 (only CAP). Bleaching was conducted over three sessions for a total of 20 min. The bleaching effect was evaluated based on the changes in color (ΔE00 and WID) and lightness (ΔL⁎ and ΔG). Safety was assessed by examining the dark areas on the enamel and monitoring the pulp chamber temperature. The study analyzed how different bleaching methods and durations affected ΔE00 and ΔWID using repeated-measures analysis of variance (ANOVA). The Kruskal-Wallis and Mann-Whitney tests were used for ΔL⁎ and dark areas, and one-way ANOVA for ΔG after 20 min of bleaching.

RESULTS

The ΔE00 and WID demonstrated an interaction based on the bleaching method and time, with Group 1 exhibiting the highest ΔE00 and WID at all treatment times (p < 0.001). ΔL⁎ and ΔG did not differ significantly between Groups 1 and 2 (p = 0.056 and 0.062, respectively) and were lowest in Group 3 (p < 0.001). Group 1 exhibited the darkest areas and highest pulp chamber temperatures (p < 0.001). Group 1 exhibited statistically significant color changes. Group 2 demonstrated similar effects, but with enhanced safety profiles.

CONCLUSIONS

Group 2, although displaying a slightly less pronounced color change compared with Group 1, achieved a color alteration readily discernible to the naked eye. This suggests that CAP with 35 % HP could be an interesting area for further investigation as an alternative to traditional in-office bleaching methods.

Comparing Redox and Intracellular Signalling Responses to Cold Plasma in Wound Healing and Cancer

Cold plasma (CP) is an ionised gas containing excited molecules and ions, radicals, and free electrons, and which emits electric fields and UV radiation. CP is potently antimicrobial, and can be applied safely to biological tissue, birthing the field of plasma medicine. Reactive oxygen and nitrogen species (RONS) produced by CP affect biological processes directly or indirectly via the modification of cellular lipids, proteins, DNA, and intracellular signalling pathways. CP can be applied at lower levels for oxidative eustress to activate cell proliferation, motility, migration, and antioxidant production in normal cells, mainly potentiated by the unfolded protein response, the nuclear factor-erythroid factor 2-related factor 2 (Nrf2)-activated antioxidant response element, and the phosphoinositide 3-kinase/protein kinase B (PI3K/Akt) pathway, which also activates nuclear factor-kappa B (NFκB). At higher CP exposures, inactivation, apoptosis, and autophagy of malignant cells can occur via the degradation of the PI3K/Akt and mitogen-activated protein kinase (MAPK)-dependent and -independent activation of the master tumour suppressor p53, leading to caspase-mediated cell death. These opposing responses validate a hormesis approach to plasma medicine. Clinical applications of CP are becoming increasingly realised in wound healing, while clinical effectiveness in tumours is currently coming to light. This review will outline advances in plasma medicine and compare the main redox and intracellular signalling responses to CP in wound healing and cancer.

Influence of Biofilm Maturity on the Antibacterial Efficacy of Cold Atmospheric Plasma in Oral Microcosm Biofilms

As biofilms mature, biomass and extracellular polysaccharide (EPS) content increases, enhancing pathogenicity. Therefore, this study aimed to evaluate the antibacterial efficacy of cold atmospheric plasma (CAP) against oral microcosm biofilms and the influence of biofilm maturity on treatment. Oral microcosm biofilms were cultured on hydroxyapatite disks for 2 and 6 days. Based on the treatment and biofilm maturity, these were subsequently allocated into six groups (N = 19 each): Groups 1 and 2 were incubated with distilled water for 1 min; Groups 3 and 4 were treated with CAP for 2 min, and Groups 5 and 6 were treated with 0.12% chlorhexidine gluconate for 1 min. Groups 1, 3, and 5 represent 2-day biofilms, and Groups 2, 4, and 6 represent 6-day biofilms. Treatments were repeated daily for 5 days. Antibacterial efficacy was analyzed by measuring oral biofilms' red fluorescence intensity (RatioR/G) and quantifying EPS content and bacterial viability. The RatioR/G was 1.089-fold and 1.104-fold higher in Groups 4 and 6 than in Groups 3 and 5 following antibacterial treatment, respectively (p < 0.001). EPS content increased by 1.71-fold in Group 6 than in Group 5 (p < 0.001). Bacterial survival rate was the lowest in Group 3 (p = 0.005). These findings underscore the relevance of CAP treatment in maintaining antibacterial efficacy regardless of the biofilm development stage, highlighting its potential utility in oral care.

An overview of the bacterial microbiome of public transportation systems-risks, detection, and countermeasures

When we humans travel, our microorganisms come along. These can be harmless but also pathogenic, and are spread by touching surfaces or breathing aerosols in the passenger cabins. As the pandemic with SARS-CoV-2 has shown, those environments display a risk for infection transmission. For a risk reduction, countermeasures such as wearing face masks and distancing were applied in many places, yet had a significant social impact. Nevertheless, the next pandemic will come and additional countermeasures that contribute to the risk reduction are needed to keep commuters safe and reduce the spread of microorganisms and pathogens, but also have as little impact as possible on the daily lives of commuters. This review describes the bacterial microbiome of subways around the world, which is mainly characterized by human-associated genera. We emphasize on healthcare-associated ESKAPE pathogens within public transport, introduce state-of-the art methods to detect common microbes and potential pathogens such as LAMP and next-generation sequencing. Further, we describe and discuss possible countermeasures that could be deployed in public transportation systems, as antimicrobial surfaces or air sterilization using plasma. Commuting in public transport can harbor risks of infection. Improving the safety of travelers can be achieved by effective detection methods, microbial reduction systems, but importantly by hand hygiene and common-sense hygiene guidelines.

Cold Atmospheric Pressure Plasma: A Growing Paradigm in Diabetic Wound Healing-Mechanism and Clinical Significance

Diabetes is one of the most significant causes of death all over the world. This illness, due to abnormal blood glucose levels, leads to impaired wound healing and, as a result, foot ulcers. These ulcers cannot heal quickly in diabetic patients and may finally result in amputation. In recent years, different research has been conducted to heal diabetic foot ulcers: one of them is using cold atmospheric pressure plasma. Nowadays, cold atmospheric pressure plasma is highly regarded in medicine because of its positive effects and lack of side effects. These conditions have caused plasma to be considered a promising technology in medicine and especially diabetic wound healing because studies show that it can heal chronic wounds that are resistant to standard treatments. The positive effects of plasma are due to different reactive species, UV radiation, and electromagnetic fields. This work reviews ongoing cold atmospheric pressure plasma improvements in diabetic wound healing. It shows that plasma can be a promising tool in treating chronic wounds, including ones resulting from diabetes.

Innovative Curved-Tip Reactor for Non-Thermal Plasma and Plasma-Treated Water Generation: Synergistic Impact Comparison with Sodium Hypochlorite in Dental Root Canal Disinfection

Non-thermal plasmas (NTPs), known as cold atmospheric plasmas (CAPs), hold great potential for diverse medical applications, including dentistry. However, traditional linear and rigid dielectric barrier discharge reactors used for NTP generation encounter limitations in accessing oral cavities and root canals. To address this issue, we have developed an innovative NTP reactor featuring an angled end for improved accessibility. The central copper electrode, with a 0.59 mm diameter and adjustable length for desired angulation, is coated with zircon powder (ZrSiO4) to ensure stable NTP generation. This central electrode is housed within a stainless steel tube (3 mm internal diameter, 8 mm external diameter, and 100 mm length) with a 27° angle at one end, making it ergonomically suitable for oral applications. NTP generation involves polarizing the reactor electrodes with 13.56 MHz radio frequency signals, using helium gas as a working medium. We introduce plasma-treated water (PTW) as an adjunctive therapy to enhance biofilm eradication within root canals. A synergistic approach combining NTP and PTW is employed and compared to the gold standard (sodium hypochlorite, NaOCl), effectively neutralizing Enterococcus faecalis bacteria, even in scenarios involving biofilms. Moreover, applying NTP in both gaseous and liquid environments successfully achieves bacterial inactivation at varying treatment durations, demonstrating the device's suitability for medical use in treating root canal biofilms. The proposed NTP reactor, characterized by its innovative design, offers a practical and specific approach to plasma treatment in dental applications. It holds promise in combatting bacterial infections in root canals and oral cavities.

Enhanced Antimicrobial Activity through Synergistic Effects of Cold Atmospheric Plasma and Plant Secondary Metabolites: Opportunities and Challenges

The emergence of antibiotic resistant microorganisms possesses a great threat to human health and the environment. Considering the exponential increase in the spread of antibiotic resistant microorganisms, it would be prudent to consider the use of alternative antimicrobial agents or therapies. Only a sustainable, sustained, determined, and coordinated international effort will provide the solutions needed for the future. Plant secondary metabolites show bactericidal and bacteriostatic activity similar to that of conventional antibiotics. However, to effectively eliminate infection, secondary metabolites may need to be activated by heat treatment or combined with other therapies. Cold atmospheric plasma therapy is yet another novel approach that has proven antimicrobial effects. In this review, we explore the physiochemical mechanisms that may give rise to the improved antimicrobial activity of secondary metabolites when combined with cold atmospheric plasma therapy.

Decreased inflammatory profile in oral leukoplakia tissue exposed to cold physical plasma ex vivo

BACKGROUND

Oral leukoplakia (OL) is an unfavorable oral disease often resistant to therapy. To this end, cold physical plasma technology was explored as a novel therapeutic agent in an experimental setup.

METHODS

Biopsies with a diameter of 3 mm were obtained from non-diseased and OL tissues. Subsequently, cold atmospheric pressure plasma (CAP) exposure was performed ex vivo in the laboratory. After 20 h of incubation, biopsies were cryo-conserved, and tissue sections were quantified for lymphocyte infiltrates, discriminating between naïve and memory cytotoxic and T-helper cells. In addition, the secretion pattern related to inflammation was investigated in the tissue culture supernatants by quantifying 10 chemokines and cytokines.

RESULTS

In CAP-treated OL tissue, significantly decreased overall lymphocyte numbers were observed. In addition, reduced levels were observed when discriminating for the T-cell subpopulations but did not reach statistical significance. Moreover, CAP treatment significantly reduced levels of C-X-C motif chemokine 10 (CXCL10) and granulocyte-macrophage colony-stimulating factor in the OL biopsies' supernatants. In idiopathically inflamed tissues, ex vivo CAP exposure reduced T-cells and CXCL10 as well but also led to markedly increased interleukin-1β secretion.

CONCLUSION

Our findings suggest CAP to have immuno-modulatory properties, which could be of therapeutic significance in the therapy of OL. Future studies should investigate the efficacy of CAP therapy in vivo in a larger cohort.

The Effectiveness of Cold Atmospheric Plasma (CAP) on Bacterial Reduction in Dental Implants: A Systematic Review

BACKGROUND

The emergence of dental implants has revolutionized the management of tooth loss. However, the placement of clinical implants exposes them to complex oral environment and numerous microscopic entities, such as bacteria. Cold atmospheric plasma (CAP) is often used to treat the surfaces of dental implants, which alters morphological features and effectively reduces bacterial load.

PURPOSE

This systematic review aims to assess the existing literature on the bactericidal properties of CAP when used on various kinds of dental implant surfaces.

REVIEW METHOD

An in-depth examination of MEDLINE/PubMed and EMBASE was performed to identify relevant studies, with the most recent search conducted in May 2023. Studies were selected based on their exploration of CAP's effects on dental implants compared to control groups, focusing on CAP's bactericidal efficacy. However, studies that lacked a control group or that failed to measure bactericidal effects were excluded.

RESULTS

After applying the selection criteria, 15 studies were ultimately included in the systematic review. The collected data suggest that CAP can effectively reduce bacterial loads on dental implant surfaces, including pathogens like Streptococcus mitis and Staphylococcus aureus. Furthermore, CAP appears to combat biofilms and plaques that are key contributors to periimplantitis.

CONCLUSION

CAP emerges as a promising treatment option, exhibiting significant bactericidal activity on dental implant surfaces. CAP can decrease the rates of bacterial biofilm and plaque formation, leading to improved outcomes for dental implant patients.

Antimicrobial Effects of Non-Thermal Atmospheric Pressure Plasma on Oral Microcosm Biofilms

We comparatively evaluated the antibacterial effects of non-thermal atmospheric pressure plasma (NTAPP) on oral microcosm biofilms. Oral microcosm biofilms, which are derived from inoculation with human saliva, were cultured on 48 hydroxyapatite disks for 6 days. The prepared biofilms were divided into three different daily treatment groups: distilled water for 1 min, 0.12% chlorhexidine (CHX) for 1 min, and NTAPP for 5 min. Using a quantitative light-induced fluorescence-digital camera, the red fluorescence intensity of the biofilms was measured as red/green ratios (Ratio_R/G) before and after treatment. Total and aciduric bacteria were counted as colony-forming units. Using live/dead bacterial staining, bacterial viability was calculated as the Ratio_G/G+R. Ratio_R/G was approximately 0.91-fold lower in the NTAPP group than in the CHX group on day 1 of treatment (p = 0.001), and approximately 0.94-fold lower on both days 2 and 3 (p < 0.001). The number of total bacteria was higher in the NTAPP group than in the CHX group, but not significantly different. The number of aciduric bacteria was lowest in the CHX group (p < 0.001). However, bacterial viability was lowest in the NTAPP group. Restricted bacterial aggregation was observed in the NTAPP group. These findings suggest that NTAPP may more effectively reduce the pathogenicity of oral microcosm biofilms than 0.12% CHX.

The effect of argon cold atmospheric plasma on the metabolism and demineralization of oral plaque biofilms

Objective

The aim of this study was to design and optimize a cold atmospheric plasma (CAP) device that could be applied in an oral environment and to study its effects on plaque biofilm metabolism and regrowth, as well as microbial flora composition and enamel demineralization.

Method

CAP was obtained through a dielectric barrier discharge device; the optical properties were analyzed using emission spectroscopy. The electrochemical analysis of plasma devices includes voltametric characteristic curves and Lissajous. The Streptococcus mutans (UA159) and saliva biofilms were treated in vitro, and the effects of CAP on biofilm metabolism were investigated using MTT and lactate dehydrogenase assays. The duration of antibacterial activity on biofilms was examined, scanning electron microscopy was used to observe the morphology of biofilms, and 16S rRNA sequencing was used to explore the influence of CAP on the microbial flora composition of saliva biofilms. An in vitro model of biofilm-enamel demineralization was designed, and the effect of CAP on enamel demineralization was evaluated by micro surface hardness and micro-CT analysis.

Results

CAP had antibacterial proliferative ability toward Streptococcus mutans biofilms and saliva biofilms and was stronger than ultraviolet under the same tested conditions. After 24 h, the antibacterial effect disappeared, which proved the short-term timeliness of its bactericidal ability. CAP can inhibit the acid production of biofilms, and its inhibitory effect on saliva biofilms can be extended to 24 h. CAP had a strong ability to regulate the composition of plaque biofilms, especially for Lactococcus proliferation, a major acid-producing bacterium in microcosm biofilms. The CAP-treated enamels were more acid-tolerant than non-treated controls.

Conclusion

CAP had an explicit bactericidal effect on caries-related biofilms, which is a short-term antibacterial effect. It can inhibit the acid production of biofilms and has a downregulation effect on Lactococcus in saliva biofilms. CAP can help reduce demineralization of enamel.

Effect of the pH on the Antibacterial Potential and Cytotoxicity of Different Plasma-Activated Liquids

In this study, different plasma-activated liquids were evaluated for their antimicrobial effects against Escherichia coli, as well as for their cytotoxicity on mammalian cells. The PALs were prepared from distilled (DIS), deionized (DI), filtered (FIL), and tap (TAP) water. Additionally, 0.9% NaCl saline solution (SAL) was plasma-activated. These PALs were prepared using 5 L/min air gliding arc plasma jet for up to 60.0 min of exposure. Subsequently, the physicochemical properties, such as, the oxidation-reduction potential (ORP), the pH, the conductivity, and the total dissolved solids (TDS) were characterized by a water multiparameter. The PALs obtained showed a drastic decrease in the pH with increasing plasma exposure time, in contrast, the conductivity and TDS increased. In a general trend, the UV-vis analyses identified a higher production of the following reactive species of nitrogen and oxygen (RONS), HNO₂, H₂O₂, NO₃^-, and NO₂^-. Except for the plasma-activated filtered water (PAW-FIL), where there was a change in the position of NO₂^- and NO₃^- at some pHs, The higher production of HNO₂ and H₂O₂-reactive species was observed at a low pH. Finally, the standardized suspensions of Escherichia coli were exposed to PAL for up to 60.0 min. The plasma-activated deionized water (PAW-DI pH 2.5), plasma-activated distilled water (PAW-DIS pH 2.5 and 3), and plasma-activated tap water (PAW-TAP 3.5) showed the best antimicrobial effects at exposure times of 3.0, 10.0, and 30.0 min, respectively. The MTT analysis demonstrated low toxicity of all of the PAL samples. Our results indicate that the plasma activation of different liquids using the gliding arc system can generate specific physicochemical conditions that produce excellent antibacterial effects for E. coli with a safe application, thus bringing future contributions to creating new antimicrobial protocols.

Possible Synergies of Nanomaterial-Assisted Tissue Regeneration in Plasma Medicine: Mechanisms and Safety Concerns

Cold atmospheric plasma and nanomedicine originally emerged as individual domains, but are increasingly applied in combination with each other. Most research is performed in the context of cancer treatment, with only little focus yet on the possible synergies. Many questions remain on the potential of this promising hybrid technology, particularly regarding regenerative medicine and tissue engineering. In this perspective article, we therefore start from the fundamental mechanisms in the individual technologies, in order to envision possible synergies for wound healing and tissue recovery, as well as research strategies to discover and optimize them. Among these strategies, we demonstrate how cold plasmas and nanomaterials can enhance each other's strengths and overcome each other's limitations. The parallels with cancer research, biotechnology and plasma surface modification further serve as inspiration for the envisioned synergies in tissue regeneration. The discovery and optimization of synergies may also be realized based on a profound understanding of the underlying redox- and field-related biological processes. Finally, we emphasize the toxicity concerns in plasma and nanomedicine, which may be partly remediated by their combination, but also partly amplified. A widespread use of standardized protocols and materials is therefore strongly recommended, to ensure both a fast and safe clinical implementation.

Frontiers in Atmospheric Pressure Plasma Technology

Atmospheric pressure plasmas represent a feasible and eco-friendly alternative to conventional physicochemical methods used in technology today for facing materials [...]

Applications of Plasma Produced with Electrical Discharges in Gases for Agriculture and Biomedicine

The use of thermal and non-thermal atmospheric pressure plasma to solve problems related to agriculture and biomedicine is the focus of this paper. Plasma in thermal equilibrium is used where heat is required. In agriculture, it is used to treat soil and land contaminated by the products of biomass, plastics, post-hospital and pharmaceutical waste combustion, and also by ecological phenomena that have recently been observed, such as droughts, floods and storms, leading to environmental pollution. In biomedical applications, thermal plasma is used in so-called indirect living tissue treatment. The sources of thermal plasma are arcs, plasma torches and microwave plasma reactors. In turn, atmospheric pressure cold (non-thermal) plasma is applied in agriculture and biomedicine where heat adversely affects technological processes. The thermodynamic imbalance of cold plasma makes it suitable for organic syntheses due its low power requirements and the possibility of conducting chemical reactions in gas at relatively low and close to ambient temperatures. It is also suitable in the treatment of living tissues and sterilisation of medical instruments made of materials that are non-resistant to high temperatures. Non-thermal and non-equilibrium discharges at atmospheric pressure that include dielectric barrier discharges (DBDs) and atmospheric pressure plasma jets (APPJs), as well as gliding arc (GAD), can be the source of cold plasma. This paper presents an overview of agriculture and soil protection problems and biomedical and health protection problems that can be solved with the aid of plasma produced with electrical discharges. In particular, agricultural processes related to water, sewage purification with ozone and with advanced oxidation processes, as well as those related to contaminated soil treatment and pest control, are presented. Among the biomedical applications of cold plasma, its antibacterial activity, wound healing, cancer treatment and dental problems are briefly discussed.

Applications of Plasma-Activated Water in Dentistry: A Review

The activation of water by non-thermal plasma creates a liquid with active constituents referred to as plasma-activated water (PAW). Due to its active constituents, PAW may play an important role in different fields, such as agriculture, the food industry and healthcare. Plasma liquid technology has received attention in recent years due to its versatility and good potential, mainly focused on different health care purposes. This interest has extended to dentistry, since the use of a plasma–liquid technology could bring clinical advantages, compared to direct application of non-thermal atmospheric pressure plasmas (NTAPPs). The aim of this paper is to discuss the applicability of PAW in different areas of dentistry, according to the published literature about NTAPPs and plasma–liquid technology. The direct and indirect application of NTAPPs are presented in the introduction. Posteriorly, the main reactors for generating PAW and its active constituents with a role in biomedical applications are specified, followed by a section that discusses, in detail, the use of PAW as a tool for different oral diseases.

Application of Non-Thermal Plasma to Fungal Resources

In addition to being key pathogens in plants, animals, and humans, fungi are also valuable resources in agriculture, food, medicine, industry, and the environment. The elimination of pathogenic fungi and the functional enhancement of beneficial fungi have been the major topics investigated by researchers. Non-thermal plasma (NTP) is a potential tool to inactivate pathogenic and food-spoiling fungi and functionally enhance beneficial fungi. In this review, we summarize and discuss research performed over the last decade on the use of NTP to treat both harmful and beneficial yeast- and filamentous-type fungi. NTP can efficiently inactivate fungal spores and eliminate fungal contaminants from seeds, fresh agricultural produce, food, and human skin. Studies have also demonstrated that NTP can improve the production of valuable enzymes and metabolites in fungi. Further studies are still needed to establish NTP as a method that can be used as an alternative to the conventional methods of fungal inactivation and activation.

Plasma-based strategy for inhibiting Candida albicans growth and CaMCA1 gene expression in vitro and reducing fungal pathogenicity in a murine model of vulvovaginal candidiasis

Vulvovaginal candidiasis (VVC) is a common mucosal infection, mainly caused by Candida albicans. The use of common antifungal drugs in treatment of VVC is limited due to emergence of resistant fungal strains and severe side effects. Cold atmospheric plasma (CAP) as a novel therapeutic approach is proven to display strong antifungal activity against C. albicans. In the present study, the effects of CAP treatment on virulence and pathogenicity of C. albicans in a murine model was investigated. Candida albicans was treated with CAP at different time exposures. Fungal cell morphology and the expression profile of CaMCA1 gene in CAP-treated fungus was evaluated using electron microscopy and quantitative RT-PCR. Moreover, the mice model of VVC was developed using CAP-treated and non-treated C. albicans and characterized in terms of vaginal fungal burden, the rate of hyphae formation in the vaginal tissue and fluid and the inflammation degree of mice vaginal tissue. Significant reduction in CaMCA1 expression and remarkable mitochondrial degradation were observed in CAP-treated C. albicans cells. The lowest fungal burden, reduced hyphae formation, poor adherence of yeast cells to vaginal epithelium, and the low degree of inflammation were observed in mice infected with CAP-treated C. albicans. Suppression of CaMCA1 gene and mitochondrial degradation in CAP-treated C. albicans yeast cells may diminish yeast to hyphae transition and reduce fungal pathogenicity in murine model of VVC. CAP treatment can be considered as a novel and efficient therapeutic strategy against C. albicans and related Candida infections in practice.

LAY SUMMARY

CAP was successfully used to inhibit fungal growth and CaMCA1 gene expression in C. albicans. It caused morphological alterations in membranous structures of the yeast cells and finally led to the cell death. CAP meaningfully reduced C. albicans virulence and pathogenicity in a murine model of VVC.

Toxicity Assessment of Long-Term Exposure to Non-Thermal Plasma Activated Water in Mice

Non-thermal plasma activated water (PAW) has recently emerged as a powerful antimicrobial agent. Despite numerous potential bio-medical applications, studies concerning toxicity in live animals, especially after long-term exposure, are scarce. Our study aimed to assess the effects of long-term watering with PAW on the health of CD1 mice. PAW was prepared from distilled water with a GlidArc reactor according to a previously published protocol. The pH was 2.78. The mice received PAW (experimental group) or tap water (control group) daily for 90 days as the sole water source. After 90 days, the following investigations were performed on the euthanatized animals: gross necropsy, teeth mineral composition, histopathology, immunohistochemistry, hematology, blood biochemistry, methemoglobin level and cytokine profile. Mice tolerated PAW very well and no adverse effects were observed during the entire period of the experiment. Histopathological examination of the organs and tissues did not reveal any structural changes. Moreover, the expression of proliferation markers PCNA and Ki67 has not been identified in the epithelium of the upper digestive tract, indicating the absence of any pre- or neoplastic transformations. The results of our study demonstrated that long-term exposure to PAW caused no toxic effects and could be used as oral antiseptic solution in dental medicine.

Strategies toward development of antimicrobial biomaterials for dental healthcare applications

Several approaches for elimination of oral pathogens are being explored at the present time since oral diseases remain prevalent affecting approximately 3.5 billion people worldwide. Need for antimicrobial biomaterials in dental healthcare include but is not restricted to designing resin composites and adhesives for prevention of dental caries. Constant efforts are also being made to develop antimicrobial strategies for clearance of endodontic space prior root canal treatment and for treatment of periimplantitis and periodontitis. This article discusses various conventional and nanotechnology-based strategies to achieve antimicrobial efficacy in dental biomaterials. Recent developments in the design and synthesis of antimicrobial peptides and antifouling zwitterionic polymers to effectively lessen the risks of antimicrobial drug resistance are also outlined in this review. Further, the role of contemporary strategies such as use of smart biomaterials, ionic solvent-based biomaterials and quorum quenchers incorporated biomaterials in the elimination of dental pathogens are described in detail. Lastly, we mentioned the approach of using polymers to print custom-made three-dimensional antibacterial dental products via additive manufacturing technologies. This review provides a critical perspective on the chemical, biomimetic, and engineering strategies intended for developing antimicrobial biomaterials that have the potential to substantially improve the dental health.

Transferred Cold Atmospheric Plasma Treatment on Melanoma Skin Cancer Cells with/without Catalase Enzyme In Vitro

Cold atmospheric plasma (CAP) is a promising tool to overcome certain cancerous and precancerous conditions in dermatology. A scheme of transferred CAP was first developed to treat melanoma (B16F10) skin cancer cells as well as non-malignant (L929) cells in vitro. CAP was transferred using a silicone tube with a jet system that was developed and was assessed as to whether it could generate reactive oxygen and nitrogen species (RONS) at near-room temperature. The transferred CAP was characterized electrically and spectroscopically. Biological data showed that the transferred CAP killed cancer cells but not non-malignant (L929) cells. Plasma treatment was effective with a time duration of 30 s, whereas non-malignant (L929) cells were less damaged during plasma treatment. In addition, catalase (CAT) enzyme was applied to neutralize and detoxify the RONS generated by the transferred CAP. These findings suggest that transferred CAP can be considered a melanoma cancer therapy.

Applications of Cold Atmospheric Pressure Plasma Technology in Medicine, Agriculture and Food Industry

In recent years, cold atmospheric pressure plasma (CAPP) technology has received substantial attention due to its valuable properties including operational simplicity, low running cost, and environmental friendliness. Several different gases (air, nitrogen, helium, argon) and techniques (corona discharge, dielectric barrier discharge, plasma jet) can be used to generate plasma at atmospheric pressure and low temperature. Plasma treatment is routinely used in materials science to modify the surface properties (e.g., wettability, chemical composition, adhesion) of a wide range of materials (e.g., polymers, textiles, metals, glasses). Moreover, CAPP seems to be a powerful tool for the inactivation of various pathogens (e.g., bacteria, fungi, viruses) in the food industry (e.g., food and packing material decontamination, shelf life extension), agriculture (e.g., disinfection of seeds, fertilizer, water, soil) and medicine (e.g., sterilization of medical equipment, implants). Plasma medicine also holds great promise for direct therapeutic treatments in dentistry (tooth bleaching), dermatology (atopic eczema, wound healing) and oncology (melanoma, glioblastoma). Overall, CAPP technology is an innovative, powerful and effective tool offering a broad application potential. However, its limitations and negative impacts need to be determined in order to receive regulatory approval and consumer acceptance.

Utilizing Radio Frequency Plasma Treatment to Modify Polymeric Materials for Biomedical Applications

Studies that utilize radio frequency plasma modification as a strategy to tune the surface properties of polymeric constructs with the goal of enhancing their use as biomedical devices have grown considerably in number over the past decade. In this Review, we present the importance of plasma surface treatment to biomedical applications, including tissue engineering and wound healing. First, we introduce several key polymeric materials of interest for use as biomaterials, including those that are naturally derived and synthetic. We, then, provide an overview of possible outcomes of plasma modification, such as surface activation, etching, and deposition of a thin film, all of which can be used to alter the surface properties of a given polymer. Following this discussion, we review the methods used to characterize plasma-treated polymer surface properties, as well as the techniques used to evaluate their interactions with biological species of interest such as mammalian cells, bacteria, and blood components. To close, we provide a perspective on future outlooks of this exciting and rapidly evolving field.