ROS from Physical Plasmas: Redox Chemistry for Biomedical Therapy

Antitumor effects of plasma‑activated solution on a murine melanoma model in vivo and in vitro

Melanoma is a common malignant skin tumor with highly invasive features and a high metastasis rate that can be difficult to treat clinically. Large-scale resection of primary cutaneous melanoma is often used to avoid postoperative recurrence. For advanced patients, radiotherapy, targeted therapy and immunotherapy are often needed. Low-temperature plasma has been proved to have significant antitumor effects on a variety of cancer cell lines cultured in vitro. The main limitation of direct low-temperature plasma treatment is that it has weak penetration ability and can only treat superficial lesions. In recent years, research on low-temperature plasma-activated solution has revealed that it also have good antitumor effects and low-temperature plasma penetration depth problems can be solved by local injection. The present study revealed that low-temperature plasma-activated phosphate buffer solution exhibited good antitumor effects and biosafety against melanoma in vitro and in vivo. It demonstrated that low-temperature plasma-activated solution has antitumor effects due to its regulation of intracellular redox, destruction of mitochondrial function and DNA damage. In vivo experiments demonstrated that treatment with low-temperature plasma-activated solution not only exhibited antitumor effects but also caused no significant damage to hematopoietic function or liver and kidney functions in mice. All these results demonstrated that low-temperature plasma-activated solution represent a promising antitumor treatment strategy.

Radical formation in skin and preclinical characterization of a novel medical plasma device for dermatology after single application

Cold atmospheric plasma (CAP) enables painless tissue treatment by producing reactive species including excited molecules and charged particles and is of great interest for medical applications. Medical CAP sources work in contact with air at ambient pressure, resulting in the generation of substantial amounts of reactive oxygen and nitrogen radicals. These radicals have a significant influence on cellular biochemistry, are crucial components of the immune system, and play a central role in wound therapy. CAP has a variety of applications, with a particular emphasis on tissue treatment in dermatology. It eradicates microorganisms by preventing biofilm formation so that wounds can be effectively disinfected and treated antiseptically. Using both in vitro and ex vivo methods, a comprehensive preclinical assessment of a novel battery-operated cold plasma handheld device with a reusable, and autoclavable glass cylinder was performed. The objectives were to evaluate the potential impact of single CAP application on radical formation with and without wound dressing, by directly measuring radicals in skin, to investigate the influence of CAP application on antimicrobial activity and cytotoxicity in vitro, and to assess skin tolerance ex vivo. The direct effect of CAP on the formation of radicals in the skin after plasma application at different levels with and without wound dressing was demonstrated quantitatively for the first time using electron paramagnetic resonance spectroscopy. Free radicals were measured in the skin as a function of the duration of CAP treatment. Furthermore, it was found that an alginate or wound plaster dressing does not significantly inhibit radical formation in skin compared to application without a dressing. In vitro and ex vivo data showed no cytotoxic potential with simultaneous efficacy against bacteria strains and no risk of temperature rise, pH change, skin barrier or DNA damage. These results show a high potential for wound healing applications in vivo.

Plasma-activated medium suppresses proliferation and migration of human lung cancer cells by regulating PI3K/AKT-Wnt signaling pathway

The main causes of high mortality in lung cancer patients are the malignant growth and migration of cancer cells. This study aims to investigate the underlying mechanisms of low-temperature plasma-activated medium (PAM) treating human lung cancer (HLC). Changes in the levels of reactive oxygen and nitrogen species both inside and outside the cells were evaluated. Our results showed that prolonged PAM exposure decreased cell viability, raised intracellular reactive oxygen species levels, and hindered cell migration while reducing mitochondrial membrane potential. Protein analysis revealed PAM increased GSK-3β and p-β-catenin expression but decreased PI3K, AKT, p-AKT, p-GSK-3β, Wnt, and β-catenin levels, thereby inhibiting the epithelial-mesenchymal transition. These findings suggest PAM suppresses HLC cells proliferation and migration by blocking the PI3K/AKT-Wnt pathway. The study will provide a valuable theoretical basis for future low-temperature plasma treatment, thereby improving the survival rates and prognosis of lung cancer.

Targeting cholangiocarcinoma cells by cold piezoelectric plasmas: in vitro efficacy and cellular mechanisms

Cold piezoelectric plasma (CPP) is a novel approach in cancer therapy, enabling the development of portable treatment devices capable of triggering cancer cell death. While its effectiveness remains underexplored, this research focuses on its application against cholangiocarcinoma (CCA), an aggressive cancer of the biliary tract. A CPP device is utilized to generate either a corona discharge (Pz-CD) or a dielectric barrier discharge (Pz-DBD) for in vitro experiments. Notably, Pz-CD can deliver more power than Pz-DBD, although both sources produce significant levels of reactive species in plasma and liquid phases. This work shows that CPP causes a gradient increase in medium temperature from the center towards the edges of the culture well, especially for longer treatment times. Although Pz-CD heats more significantly, it cools quickly after plasma extinction. When applied to human CCA cells, CPP shows immediate and long-term effects, more localized for Pz-CD, while more uniform for Pz-DBD. Immediate effects result also in actin cytoskeleton remodeling without alteration of the cell membrane permeability. Long-term effects of CPP, although the antioxidant system is engaged, include activation of the DNA damage response pathway leading to cell death. In conclusion, CPP should be recognized as a promising antitumor therapy.

Disinfection of dental root canals by cold atmospheric plasma: a systematic review and meta-analysis of dental biofilm

Aim

The intricate structure of the tooth root canals has a role in the colonization and biofilm formation in hidden areas that are hardly reached by standard endodontic treatments. This review aims at summarizing data from in vitro and ex vivo studies for a better understanding of the application of cold atmospheric plasma (CAP) for the disinfection of dental root canals.

Methods

PubMed, Scopus, and Web of Science databases were screened. Characteristics of the included studies were extracted, and a meta-analysis on ex vivo studies was carried out to evaluate the effect of CAP on colony forming unit assay of Enterococcus faecalis (E. faecalis). The study was performed following the PRISMA 2020 guidelines.

Results

A total of 31 studies fulfilled the selection criteria. Only 2 investigations reported an indirect plasma treatment, 28 trials used direct CAP administration, while 1 study applied both methods. Most of the studies were conducted on E. faecalis using as carrier gas Helium or Argon alone or in combination with Oxygen as well air. A considerable heterogeneity among studies was found regarding treatments which varied for source type, settings, and protocols of application. Despite this, CAP showed effectiveness in reducing E. faecalis colony forming unit with a standardized mean difference of 4.51, 95% C.I. = 2.55-6.48, p-value < 0.001.

Conclusion

The data demonstrated the antimicrobial effect of direct CAP application against microorganisms. In-vitro studies showed an effect that depended on the time and distance of treatment, while the meta-analysis performed on ex vivo studies showed that the effect of CAP was independent of time and distance.

Systematic Review Registration

https://doi.org/10.17605/OSF.IO/BJ59V, identifier OSF registries.

Enhancing antitumor immunity in Lewis lung cancer through plasma-treated medium-induced activation of dendritic cells

BACKGROUND

Recently, atmospheric non-thermal plasma jet-treated medium (PTM) has been recognized as a novel strategy in cancer therapy and lymphocyte activation. However, PTM has limitations in inducing a robust antitumor-immune response. This study demonstrated that PTM treatment inhibited tumor progression by activating dendritic cells (DCs).

METHOD

In this study, we investigated the effects of PTM on selective cytotoxicity and intracellular reactive oxygen species (ROS) generation and oxidative stress-mediated signaling (e.g., glutathione peroxidase, catalase) using respective fluorescence probes in Lewis lung cancer (LLC) cells. Then, the PTM affects the expression of interferon-gamma (IFN)-γ-induced programmed death-ligand 1 (PD-L1) and inhibition of signal transducer and activator of transcription 1 (STAT1) in LLC cells using immunoblotting. Additionally, PTM effects on the tumor cell's death and activation of DCs were done by co-culturing DCs with or without tumor cells. Further, a mouse model was used to evaluate the synergistic antitumor effects of PTM and DCs where tumors are grown under the skin.

RESULTS

PTM-exposed tumor cells increase intracellular superoxide production, enhancing ROS generation and leading to cancer immunogenic cell death. In addition, PTM suppresses IFN-γ-induced PD-L1 expression and STAT1 activation in tumor cells. The activation of DCs induced by PTM is downregulated when these cells are co-cultured with tumor cells. In vivo, intraperitoneal injection of PTM-activated DCs, as a synergistic agent to intertumoral PTM treatment, led to increased CD4+ and CD8+ T cell infiltration into the tumor and spleen and eventually decreased tumor growth.

CONCLUSION

Overall, this research introduces a promising avenue for improving lung cancer treatment using PTM to stimulate an immune response and induce cell death in tumor cells. Further studies will be essential to validate these findings and explore clinical applications.

Reactive oxygen species from non-thermal gas plasma (CAP): implication for targeting cancer stem cells

Cancer remains a major global health challenge, with the persistence of cancer stem cells (CSCs) contributing to treatment resistance and relapse. Despite advancements in cancer therapy, targeting CSCs presents a significant hurdle. Non-thermal gas plasma, also known as CAP, represents an innovative cancer treatment. It has recently gained attention for its often found to be selective, immunogenic, and potent anti-cancer properties. CAP is composed of a collection of transient, high-energy, and physically and chemically active entities, such as reactive oxygen species (ROS). It is acknowledged that the latter are responsible for a major portion of biomedical CAP effects. The dynamic interplay of CAP-derived ROS and other components contributes to the unique and versatile properties of CAP, enabling it to interact with biological systems and elicit various therapeutic effects, including its potential in cancer treatment. While CAP has shown promise in various cancer types, its application against CSCs is relatively unexplored. This review assesses the potential of CAP as a therapeutic strategy for targeting CSCs, focusing on its ability to regulate cellular states and achieve redox homeostasis. This is done by providing an overview of CSC characteristics and demonstrating recent findings on CAP's efficacy in targeting these cells. By contributing insights into the unique attributes of CSCs and the potential of CAP, this work contributes to an advanced understanding of innovative oncology strategies.

Cold atmospheric plasma (CAP): a revolutionary approach in dermatology and skincare

Cold atmospheric plasma (CAP) technology has emerged as a revolutionary therapeutic technology in dermatology, recognized for its safety, effectiveness, and minimal side effects. CAP demonstrates substantial antimicrobial properties against bacteria, viruses, and fungi, promotes tissue proliferation and wound healing, and inhibits the growth and migration of tumor cells. This paper explores the versatile applications of CAP in dermatology, skin health, and skincare. It provides an in-depth analysis of plasma technology, medical plasma applications, and CAP. The review covers the classification of CAP, its direct and indirect applications, and the penetration and mechanisms of action of its active components in the skin. Briefly introduce CAP's suppressive effects on microbial infections, detailing its impact on infectious skin diseases and its specific effects on bacteria, fungi, viruses, and parasites. It also highlights CAP's role in promoting tissue proliferation and wound healing and its effectiveness in treating inflammatory skin diseases such as psoriasis, atopic dermatitis, and vitiligo. Additionally, the review examines CAP's potential in suppressing tumor cell proliferation and migration and its applications in cosmetic and skincare treatments. The therapeutic potential of CAP in treating immune-mediated skin diseases is also discussed. CAP presents significant promise as a dermatological treatment, offering a safe and effective approach for various skin conditions. Its ability to operate at room temperature and its broad spectrum of applications make it a valuable tool in dermatology. Finally, introduce further research is required to fully elucidate its mechanisms, optimize its use, and expand its clinical applications.

A combined treatment for self-traumatic chronic skin lesions associated with post-surgical neuropathic pain in a domestic cat: a pharmacological and cold atmospheric plasma approach

Cold atmospheric plasma (CAP) has been employed as a therapy against both acute and chronic skin lesions, contaminated or not, and has effects on angiogenesis and reepithelialization promoting healing. In this context, the present study aimed to evaluate the effects of a CAP jet associated with pharmacological treatment described by the 2015 AAHA/AAFP pain management guidelines and the 2022 WSAVA guidelines for the recognition, assessment, and treatment of pain, on the healing of chronic skin lesions caused by a pruritic reaction resulting from post-surgical neuropathic pain. To this end, a single CAP application was performed on a feline patient with a 6 months old recurrent contaminated cervical skin lesions along with administration of ketamine (10 µg/kg/min) following the prescription of prednisone (1 mg/kg, SID, 6 days), gabapentin (8 mg/kg, BID, 60 days) and amitriptyline (0.5 mg /kg, SID, 60 days). A single application of plasma associated with an NMDA antagonist, anti-inflammatory steroid, tricyclic antidepressant and gabapentinoid thus provided a significant improvement in the macroscopic appearance of the lesion within 10 days, and the owner reported the cessation of intense itching within the first four hours after treatment and a consequent improvement in the animal's quality of life. The medical treatment was finished almost a year since the writing of this paper, without clinical or reported recurrent signs of the condition. Therefore, we observed that single dose CAP application associated with ketamine, gabapentin, amitriptyline and prednisone leads to significant healing of chronically infected skin lesions resulting from post-surgical neuropathic pain.

A Bioinspired Photosensitizer Performs Tumor Thermoresistance Reversion to Optimize the Atraumatic Mild-Hyperthermia Photothermal Therapy for Breast Cancer

Mild-hyperthermia photothermal therapy (mPTT) has therapeutic potential with minimized damage to normal tissues. However, the poorly vascularized tumor area severely hampers the penetration of photothermal agents (PTAs), resulting in their heterogeneous distribution and the subsequent heterogeneous local temperature during mPTT. The presence of regions below the therapeutic 42 °C threshold can lead to incomplete tumor ablation and potential recurrence. Additionally, tumor anti-apoptosis and cytoprotection pathways, particularly activated thermoresistance, can nullify mild hyperthermia-induced tumor damage. Therefore, a bioinspired photosensitizer decorated with leucine to form biomimetic nanoclusters (CP-PLeu nanoparticles (NPs)) aimed at achieving rapid and homogeneous accumulation in tumors, is introduced. Moreover, CP-PLeu exhibits photodynamic effects that reverse tumor thermoresistance and physiological repair mechanisms, thereby inhibiting tumor resistance to hyperthermia. With the addition of NIR-II laser irradiation, CP-PLeu optimizes the therapeutic efficacy of mPTT and contributes to a minimally invasive therapeutic process for breast cancer. This therapeutic strategy, utilizing a biomimetic photosensitizer for homogeneous distribution of therapeutic temperature and photoactivated reversal of tumor thermoresistance, successfully achieves efficient breast tumor inhibition through an atraumatic mPTT process.

Cold atmospheric plasma-activated medium for potential ovarian cancer therapy

Cold atmospheric plasma (CAP) has emerged as an innovative tool with broad medical applications, including ovarian cancer (OC) treatment. By bringing CAP in close proximity to liquids such as water or cell culture media, solutions containing reactive oxygen species (ROS) and reactive nitrogen species (RNS) are generated, called plasma-activated media (PAM). In this systematic review, we conduct an in-depth analysis of studies focusing on PAM interactions with biological substrates. We elucidate the diverse mechanisms involved in the activation of different media and the complex network of chemical reactions underlying the generation and consumption of the prominent reactive species. Furthermore, we highlight the promises of PAM in advancing biomedical applications, such as its stability for extended periods under appropriate storage conditions. We also examine the application of PAM as an anti-cancer and anti-metastatic treatment for OC, with a particular emphasis on its ability to induce apoptosis via distinct signaling pathways, inhibit cell growth, suppress cell motility, and enhance the therapeutic effects of chemotherapy. Finally, the future outlook of PAM therapy in biomedical applications is speculated, with emphasis on the safety issues relevant to clinical translation.

YAP/TAZ, beta-catenin, and TGFb pathway activation in medical plasma-induced wound healing in diabetic mice

INTRODUCTION

Hippo is a signaling pathway that is evolutionarily conserved and plays critical roles in wound healing and tissue regeneration. Disruption of the transcriptional activity of both Hippo-associated factors, the yes-associated protein (YAP), and the transcriptional co-activator with PDZ binding motif (TAZ) has been associated with cardiovascular diseases, fibrosis, and cancer. This makes the Hippo pathway an appealing target for therapeutic interventions.

OBJECTIVES

Prior research has indicated that medical gas plasma promotes wound healing by delivering a combination of reactive species directly to the affected areas. However, the involvement of YAP/TAZ and other signaling pathways in diabetic wound healing remains unexplored.

METHODS

To this extent, ear wounds were generated and treated with gas plasma in streptozotocin (STZ)-induced diabetic mice. Transcriptome profiling at two wound healing stages (days 9 and 20 post-wounding) was performed in female and male mice. Additionally, we employed gene and protein expression analyses, utilizing immunohistological and -chemical staining of various targets as well as quantitative PCR and Western blot analysis.

RESULTS

Gas plasma treatment accelerated healing by increasing re-epithelialization and modifying extracellular matrix components. Transcriptomic profiling charting the major alterations in gene expression following plasma treatment was followed by a validation of several targets using transcriptional and translational quantification as well as localization analyses.

CONCLUSION

Our study evaluated the cellular regulation of essential targets of the Hippo and related pathways such as YAP/TAZ, β-catenin, tumor growth factor β, and oxidative stress signaling after plasma treatment. The activation of genes, pathways, and their regulators is an attractive therapeutic aim for a therapeutic intervention in dermal skin repair in diabetic diseases using medical gas plasmas.

Low-temperature plasma jet suppresses bacterial colonisation and affects wound healing through reactive species

An argon-based low-temperature plasma jet (LTPJ) was used to treat chronically infected wounds in Staphylococcus aureus-laden mice. Based on physicochemical property analysis and in vitro antibacterial experiments, the effects of plasma parameters on the reactive nitrogen and oxygen species (RNOS) content and antibacterial capacity were determined, and the optimal treatment parameters were determined to be 4 standard litre per minute and 35 W. Additionally, the plasma-treated activation solution had a bactericidal effect. Although RNOS are related to the antimicrobial effect of plasma, excess RNOS may be detrimental to wound remodelling. In vivo studies demonstrated that medium-dose LTPJ promoted MMP-9 expression and inhibited bacterial growth during the early stages of healing. Moreover, LTPJ increased collagen deposition, reduced inflammation, and restored blood vessel density and TGF-β levels to normal in the later stages of wound healing. Therefore, when treating chronically infected wounds with LTPJ, selecting the medium dose of plasma is more advantageous for wound recovery. Overall, our study demonstrated that low-temperature plasma jets may be a potential tool for the treatment of chronically infected wounds.

Antimicrobial efficacy of direct air gas soft jet plasma for the in vitro reduction of oral bacterial biofilms

The aim of this study was to evaluate the antimicrobial efficacy of an air gas soft jet CAP for its potential use in removing oral biofilms, given that plasma-based technologies have emerged as promising methods in periodontology. Two types of biofilms were developed, one by Streptococcus mutans UA 159 bacterial strain and the other by a complex mixture of saliva microorganisms isolated from a patient with periodontitis. This latter biofilm was characterized via Next Generation Sequencing to determine the main bacterial phyla. The CAP source was applied at a distance of 6 mm for different time points. A statistically significant reduction of both CFU count and XTT was already detected after 60 s of CAP treatment. CLSM analysis supported CAP effectiveness in killing the microorganisms inside the biofilm and in reducing the thickness of the biofilm matrix. Cytotoxicity tests demonstrated the possible use of CAP without important side effects towards human gingival fibroblasts cell line. The current study showed that CAP treatment was able to significantly reduce preformed biofilms developed by both S. mutans and microorganisms isolated by a saliva sample. Further studies should be conducted on biofilms developed by additional saliva donors to support the potential of this innovative strategy to counteract oral pathogens responsible for periodontal diseases.

Engineering alginate-based injectable hydrogels combined with bioactive polymers for targeted plasma-derived oxidative stress delivery in osteosarcoma therapy

Reactive Oxygen and Nitrogen Species (RONS) in biological systems display hormetic effects, capable of either promoting cell regenerative effects or inducing cell death. Recently, hydrogels have emerged as a promising delivery platform for RONS generated from Cold Atmospheric Plasmas (CAP), known as Plasma-Treated Hydrogels (PTH). PTH have been proposed as an alternative therapy to conventional cancer treatments, offering reduced side effects through the controlled and localized delivery of plasma-derived RONS. In this work, we have developed alginate-based PTH with dual therapeutic action provided by plasma-derived RONS acting as selective anticancer agents for osteosarcoma treatment, and biomolecules (hyaluronic acid and gelatin) to promote stem cell-mediated bone regeneration. For this purpose, we designed a novel manufacturing process to maximize the load of plasma-derived RONS within the PTH. Then, we assessed the PTH bioactivity on osteosarcoma MG-63 cells, and human mesenchymal stem cells (hMSCs). The results showed that the PTH composed of 0.25 % alginate +1 % hyaluronic acid is the most promising formulation in osteosarcoma treatment, showing a dual-action bioactivity as a selective cytotoxic anticancer agent, and as promoter of the proliferation and osteogenic differentiation of hMSCs. These findings provide strong evidence of the significant potential of PTH in the oncological field.

Delivery Systems for Plasma-reactive Species and their Applications in the Field of Biomedicine

Cold atmospheric plasma (CAP) is an ionized matter with potential applications in various medical fields, ranging from wound healing and disinfection to cancer treatment. CAP's clinical usefulness stems from its ability to act as an adjustable source of reactive oxygen and nitrogen species (RONS), which are known to function as pleiotropic signaling agents within cells. Plasma-activated species, such as RONS, have the potential to be consistently and precisely released by carriers, enabling their utilization in a wide array of biomedical applications. Furthermore, understanding the behavior of CAP in different environments, including water, salt solutions, culture medium, hydrogels, and nanoparticles, may lead to new opportunities for maximizing its therapeutic potential. This review article sought to provide a comprehensive and critical analysis of current biomaterial approaches for the targeted delivery of plasma-activated species in the hope to boost therapeutic response and clinical applicability.

Gas plasmas technology: from biomolecule redox research to medical therapy

Physical plasma is one consequence of gas ionization, i.e. its dissociation of electrons and ions. If operated in ambient air containing oxygen and nitrogen, its high reactivity produces various reactive oxygen and nitrogen species (RONS) simultaneously. Technology leap innovations in the early 2010s facilitated the generation of gas plasmas aimed at clinics and operated at body temperature, enabling their potential use in medicine. In parallel, their high potency as antimicrobial agents was systematically discovered. In combination with first successful clinical trials, this led in 2013 to the clinical approval of first medical gas plasma devices in Europe for promoting the healing of chronic and infected wounds and ulcers in dermatology. While since then, thousands of patients have benefited from medical gas plasma therapy, only the appreciation of the critical role of gas plasma-derived RONS led to unraveling first fragments of the mechanistic basics of gas plasma-mediated biomedical effects. However, drawing the complete picture of effectors and effects is still challenging. This is because gas plasma-produced RONS not only show a great variety of dozens of types but also each of them having distinct spatio-temporal concentration profiles due to their specific half-lives and reactivity with other types of RONS as well as different types of (bio) molecules they can react with. However, this makes gas plasmas fascinating and highly versatile tools for biomolecular redox research, especially considering that the technical capacity of increasing and decreasing individual RONS types holds excellent potential for tailoring gas plasmas toward specific applications and disease therapies.

Easy cleaning plus stable activation of glassy carbon electrode surface by oxygen plasma

Glassy carbon (GC) electrodes are widely used in electroanalytical applications especially in bioelectrochemistry. Their use starts with an efficient surface cleaning and activation protocol, mostly based on surface polishing steps. We studied the use of an oxygen plasma exposure of GC electrodes to replace common polishing procedures. The cyclic voltammetry (CV) responses of ferrocyanide and ferrocene-dimethanol were used to compare brand new, surface-polished and plasma-treated GC electrodes. Plasma treatment induces CV responses with improved features, close to theoretical values, as compared to other methods. The plasma effects were quasi-stable over a week when electrodes were stored in water, this being explained by increased surface energy and hydrophilicity. Furthermore, when electroreduction of diazonium was performed on GC electrodes, the surface blockade could be removed by the plasma. Thus, a short oxygen plasma treatment is prone to replace polishing protocols, that display person-dependent efficiency, in most of the experiments with GC electrodes.

Toxicity study of rats treated by plasma-activated solution

Background

Cold atmospheric plasma (CAP) is an effective treatment for various skin diseases. Plasma-activated solution (PAS) is an indirect method of CAP treatment that produces biological effects similar to those of direct treatment with plasma devices. The anticancer and bacteriostatic effects of PAS have been demonstrated in vitro experiments; however, on the basis of the lack of toxicological studies on PAS, its effects on living mammals when administered by subcutaneous injection is poorly known.

Purpose

The purpose of this study was to evaluate the effects of PAS on local skin tissue cells, blood system, heart, liver, lungs, kidneys and other vital organs of the rat when injected subcutaneously.

Methods

PAS was prepared by CAP irradiation of phosphate-buffered saline (PBS). PBS and different PBS groups (CAP irradiation for 1, 3, or 5 min) were injected subcutaneously once every 48 h. The rats were euthanized immediately after 10 cycles of therapy.

Results

No adverse effects were observed during the entire period of the experiment. Histopathological examination of organs and tissues revealed no structural changes. Moreover, no obvious structural changes were observed in skin tissue. DNA damage and cancerous proliferative changes were not detected in skin tissue treated with PAS. Subsequently, RNA sequencing and western blotting were performed. The results showed that PAS increased the expression of growth factors like transforming growth factor beta (TGF-β) and vascular endothelial growth factor A (VEGFA). These results might be directly linked to the role of PAS in stimulating TGF-β receptor signaling pathway and angiogenesis.

Conclusion

The results showed that multiple subcutaneous injections of PAS did not show significant toxic side effects on local skin tissues and some vital organs in rats, providing a scientific basis to support the future treatment of skin diseases with PAS.

Charge decay in the spatial afterglow of plasmas and its impact on diffusion regimes

The spatial afterglow is a region at the boundary of a non-equilibrium plasma where charged species relax into ambient equilibrium. In many applications, the spatial afterglow is the part of the plasma that interacts with surfaces, such as suspended particles or a material substrate. However, compared to the bulk plasma, there has been little effort devoted to studying the properties of the spatial afterglow, and a fundamental analysis has not yet been developed. Here, we apply double Langmuir probe measurements and develop an advection-diffusion-recombination model to provide a detailed description of charged species in the spatial afterglow over a wide range of pressures, temperatures, plasma dimensions, and flow rates. We find that the density of charged species in the spatial afterglow decays by orders of magnitude, which leads to a transition from ambipolar to free diffusion. These insights can be used to explain or predict experimental observations of phenomena, such as the charging of dust grains and the dose of charged species to a biomaterial.

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 effect of low-intensity cold atmospheric plasma jet on photoaging-induced hyperpigmentation in mouse model

BACKGROUND

Cold atmospheric plasma (CAP) produces reactive oxygen/nitrogen species (RONS) in the target and can induce cytoprotective effects by activating hormesis-related pathways when its intensity is in the low range.

OBJECTIVES

The aim of this study is to evaluate the effect of low-intensified CAP (LICAP) on skin with photoaging-induced hyperpigmentation in an animal model.

METHODS

Changes in cell viability and RONS production following LICAP treatment were measured. For the in vivo study, 30 hairless mice underwent antecedent photoaging induction followed by the allocated therapy (i.e., LICAP, topical ascorbic acid (AA), or both). During the first 4 weeks of the treatment period (8 weeks), ultraviolet (UV)-B irradiation was concurrently administered. Visual inspection and measurement of the melanin index (MI) were performed to assess the change in skin pigmentation at Weeks 0, 2, 4, 6, and 8.

RESULTS

RONS production increased linearly until the saturation point. Cell viability was not significantly affected by LICAP treatment. At Week 8, MI was significantly decreased in every treatment group compared with the values at Week 0 and Week 4. The treatment effect of the concurrent therapy group was superior to that of the LICAP and AA groups.

CONCLUSION

LICAP appears to be a novel modality for photoprotection and pigment reduction in photodamaged skin. LICAP treatment and topical AA application seem to exert a synergistic effect.

Medical gas plasma technology: Roadmap on cancer treatment and immunotherapy

Despite continuous therapeutic progress, cancer remains an often fatal disease. In the early 2010s, first evidence in rodent models suggested promising antitumor action of gas plasma technology. Medical gas plasma is a partially ionized gas depositing multiple physico-chemical effectors onto tissues, especially reactive oxygen and nitrogen species (ROS/RNS). Today, an evergrowing body of experimental evidence suggests multifaceted roles of medical gas plasma-derived therapeutic ROS/RNS in targeting cancer alone or in combination with oncological treatment schemes such as ionizing radiation, chemotherapy, and immunotherapy. Intriguingly, gas plasma technology was recently unraveled to have an immunological dimension by inducing immunogenic cell death, which could ultimately promote existing cancer immunotherapies via in situ or autologous tumor vaccine schemes. Together with first clinical evidence reporting beneficial effects in cancer patients following gas plasma therapy, it is time to summarize the main concepts along with the chances and limitations of medical gas plasma onco-therapy from a biological, immunological, clinical, and technological point of view.

Potentials of a Plasma-Aerosol System for Wound Healing Advanced by Drug Introduction: An In Vitro Study

Cold plasmas have found their application in a wide range of biomedical fields by virtue of their high chemical reactivity. In the past decades, many attempts have been made to use cold plasmas in wound healing, and within this field, many studies have focused on plasma-induced cell proliferation mechanisms. In this work, one step further has been taken to demonstrate the advanced role of plasma in wound healing. To this end, the simultaneous ability of plasma to induce cell proliferation and permeabilize treated cells has been examined in the current study. The driving force was to advance the wound healing effect of plasma with drug delivery. On this subject, we demonstrate in vitro the healing effect of Ar, Ar+N₂ plasma, and their aerosol counterparts. A systematic study has been carried out to study the role of reactive oxygen species (ROS) and reactive nitrogen species (RNS) in cell adhesion, signaling, differentiation, and proliferation. An additional investigation was also performed to study the permeabilization of cells and the delivery of the modeled drug carrier fluorescein isothiocyanate (FITC) labeled dextran into cells upon plasma treatment. Short 35 s plasma treatments were found to promote fibroblast adhesion, migration, signaling, proliferation, and differentiation by means of reactive oxygen and nitrogen species (RONS) created by plasma and deposited into the cell environment. The impact of the plasma downstream products NO₂^- and NO₃^- on the expressions of the focal adhesion's genes, syndecans, and collagens was observed to be prominent. On the other hand, the differentiation of fibroblasts to myofibroblasts was mainly initiated by ROS produced by the plasma. In addition, the ability of plasma to locally permeabilize fibroblast cells was demonstrated. During proliferative cell treatment, plasma can simultaneously induce cell membrane permeabilization (d ∼ 7.3 nm) by the species OH and H₂O₂. The choice for a plasma or a plasma-aerosol configuration thus allows the possibility to change the spatial chemistry of drug delivery molecules and thus to locally deliver drugs. Accordingly, this study offers a pivotal step toward plasma-assisted wound healing advanced by drug delivery.

Cold atmospheric plasma treatment enhances recombinant model protein production in yeast Pichia pastoris

Cold atmospheric pressure plasma (CAP) has been described as a novel technology with expanding applications in biomedicine and biotechnology. In the present study, we provide a mildly stressful condition using non-lethal doses of CAP (120, 180, and 240 s) and evaluate its potential benefits on the recombinant production of a model protein (enhanced green fluorescent protein (eGFP)) in yeast Pichia pastoris. The measured eGFP fluorescence augmented proportional to CAP exposure time. After 240 s treatment with CAP, the measured fluorescent intensity of culture supernatant (after 72 h) and results of real-time PCR (after 24 h) indicated an 84% and 76% increase in activity and related RNA concentration, respectively. Real-time analysis of a list of genes involved in oxidative stress response revealed a significant and durable improvement in their expression at five h and 24 h following CAP exposure. The improvement of the recombinant model protein production may be partly explained by the impact of the RONS on cellular constituents and altering the expression of specific stress genes. In conclusion, using CAP strategy may be considered a valuable strategy to improve recombinant protein production, and deciphering the molecular background mechanism could be inspiring in the reverse metabolic engineering of host cells.

Inactivation of SARS-CoV-2 and Other Enveloped and Non-Enveloped Viruses with Non-Thermal Plasma for Hospital Disinfection

As recently highlighted by the SARS-CoV-2 pandemic, viruses have become an increasing burden for health, global economy, and environment. The control of transmission by contact with contaminated materials represents a major challenge, particularly in hospital environments. However, the current disinfection methods in hospital settings suffer from numerous drawbacks. As a result, several medical supplies that cannot be properly disinfected are not reused, leading to severe shortages and increasing amounts of waste, thus prompting the search for alternative solutions. In this work, we report that non-thermal plasma (NTP) can effectively inactivate SARS-CoV-2 from non-porous and porous materials commonly found in healthcare facilities. We demonstrated that 5 min treatment with a dielectric barrier discharge NTP can inactivate 100% of SARS-CoV-2 (Wuhan and Omicron strains) from plastic material. Using porcine respiratory coronavirus (surrogate for SARS-CoV-2) and coxsackievirus B3 (highly resistant non-enveloped virus), we tested the NTP virucidal activity on hospital materials and obtained complete inactivation after 5 and 10 min, respectively. We hypothesize that the produced reactive species and local acidification contribute to the overall virucidal effect of NTP. Our results demonstrate the potential of dielectric barrier discharge NTPs for the rapid, efficient, and low-cost disinfection of healthcare materials.

Current State of Cold Atmospheric Plasma and Cancer-Immunity Cycle: Therapeutic Relevance and Overcoming Clinical Limitations Using Hydrogels

Cold atmospheric plasma (CAP) is a partially ionized gas that gains attention as a well-tolerated cancer treatment that can enhance anti-tumor immune responses, which are important for durable therapeutic effects. This review offers a comprehensive and critical summary on the current understanding of mechanisms in which CAP can assist anti-tumor immunity: induction of immunogenic cell death, oxidative post-translational modifications of the tumor and its microenvironment, epigenetic regulation of aberrant gene expression, and enhancement of immune cell functions. This should provide a rationale for the effective and meaningful clinical implementation of CAP. As discussed here, despite its potential, CAP faces different clinical limitations associated with the current CAP treatment modalities: direct exposure of cancerous cells to plasma, and indirect treatment through injection of plasma-treated liquids in the tumor. To this end, a novel modality is proposed: plasma-treated hydrogels (PTHs) that can not only help overcome some of the clinical limitations but also offer a convenient platform for combining CAP with existing drugs to improve therapeutic responses and contribute to the clinical translation of CAP. Finally, by integrating expertise in biomaterials and plasma medicine, practical considerations and prospective for the development of PTHs are offered.

Cold air plasma improving rheumatoid arthritis via mitochondrial apoptosis pathway

Rheumatoid arthritis (RA) has plagued physicians and patients for years due to the lack of targeted treatment. In this study, inspired by the commonality between rheumatoid arthritis fibroblast-like synoviocytes (RA-FLS) and cancer cells, the therapeutic effects of cold air plasma (CAP) on RA are studied systematically and thoroughly. In/ex vivo results show that CAP with the proper dosage significantly relieves symptoms including synovial hyperplasia, inflammatory infiltration, and angiogenesis and eliminates the root cause by triggering the self-antioxidant capability of the surrounding tissue. The mechanism on the molecular and cellular level is also revealed that the spontaneous reactive oxygen species (ROS) cascade induces the mitochondrial apoptosis pathway on RA-FLS. This study reveals a new strategy for targeted treatment of RA and the mechanistic study provides the theoretical foundation for future development of plasma medicine.

Modulation of Reactive Oxygen Species in Cancers: Recent Advances

Oxidation-reduction reactions played a significant role in the chemical evolution of life forms on oxygenated earth. Cellular respiration is dependent on such redox reactions, and any imbalance leads to the accumulation of reactive oxygen species (ROS), resulting in both chronic and acute illnesses. According to the International Agency for Research on Cancer (IARC), by 2040, the global burden of new cancer cases is expected to be around 27.5 million, with 16.3 million cancer deaths due to an increase in risk factors such as unhealthy lifestyle, environmental factors, aberrant gene mutations, and resistance to therapies. ROS play an important role in cellular signalling, but they can cause severe damage to tissues when present at higher levels. Elevated and chronic levels of ROS are pertinent in carcinogenesis, while several therapeutic strategies rely on altering cellular ROS to eliminate tumour cells as they are more susceptible to ROS-induced damage than normal cells. Given this selective targeting potential, therapies that can effectively modulate ROS levels have been the focus of intense research in recent years. The current review describes biologically relevant ROS, its origins in solid and haematological cancers, and the current status of evolving antioxidant and pro-oxidant therapies in cancers.

Toxicity and virucidal activity of a neon-driven micro plasma jet on eukaryotic cells and a coronavirus

Plasma medicine is a developing field that utilizes the effects of cold physical plasma on biological substrates for therapeutic purposes. Approved plasma technology is frequently used in clinics to treat chronic wounds and skin infections. One mode of action responsible for beneficial effects in patients is the potent antimicrobial activity of cold plasma systems, which is linked to their unique generation of a plethora of reactive oxygen and nitrogen species (ROS). During the SARS-CoV-2 pandemic, it became increasingly clear that societies need novel ways of passive and active protection from viral airway infections. Plasma technology may be suitable for superficial virus inactivation. Employing an optimized neon-driven micro plasma jet, treatment time-dependent ROS production and cytotoxic effects to different degrees were found in four different human cell lines with respect to their metabolic activity and viability. Using the murine hepatitis virus (MHV), a taxonomic relative of human coronaviruses, plasma exposure drastically reduced the number of infected murine fibroblasts by up to 3000-fold. Direct plasma contact (conductive) with the target maximized ROS production, cytotoxicity, and antiviral activity compared to non-conductive treatment with the remote gas phase only. Strikingly, antioxidant pretreatment reduced but not abrogated conductive plasma exposure effects, pointing to potential non-ROS-related mechanisms of antiviral activity. In summary, an optimized micro plasma jet showed antiviral activity and cytotoxicity in human cells, which was in part ROS-dependent. Further studies using more complex tissue models are needed to identify a safe dose-effect window of antiviral activity at modest toxicity.

Cold Atmospheric Plasma Jet Treatment Improves Human Keratinocyte Migration and Wound Closure Capacity without Causing Cellular Oxidative Stress

Cold Atmospheric Plasma (CAP) is an emerging technology with great potential for biomedical applications such as sterilizing equipment and antitumor strategies. CAP has also been shown to improve skin wound healing in vivo, but the biological mechanisms involved are not well known. Our study assessed a possible effect of a direct helium jet CAP treatment on keratinocytes, in both the immortalized N/TERT-1 human cell line and primary keratinocytes obtained from human skin samples. The cells were covered with 200 µL of phosphate buffered saline and exposed to the helium plasma jet for 10−120 s. In our experimental conditions, micromolar concentrations of hydrogen peroxide, nitrite and nitrate were produced. We showed that long-time CAP treatments (≥60 s) were cytotoxic, reduced keratinocyte migration, upregulated the expression of heat shock protein 27 (HSP27) and induced oxidative cell stress. In contrast, short-term CAP treatments (<60 s) were not cytotoxic, did not affect keratinocyte proliferation and differentiation, and did not induce any changes in mitochondria, but they did accelerate wound closure in vitro by improving keratinocyte migration. In conclusion, these results suggest that helium-based CAP treatments improve wound healing by stimulating keratinocyte migration. The study confirms that CAP could be a novel therapeutic method to treat recalcitrant wounds.

d-Glucose Oxidation by Cold Atmospheric Plasma-Induced Reactive Species

The glucose oxidation cascade is fascinating; although oxidation products have high economic value, they can manipulate the biological activity through posttranslational modification such as glycosylation of proteins, lipids, and nucleic acids. The concept of this work is based on the ability of reactive species induced by cold atmospheric plasma (CAP) in aqueous liquids and the corresponding gas-liquid interface to oxidize biomolecules under ambient conditions. Here, we report the oxidation of glucose by an argon-based dielectric barrier discharge plasma jet (kINPen) with a special emphasis on examining the reaction pathway to pinpoint the most prominent reactive species engaged in the observed oxidative transformation. Employing d-glucose and d-glucose-¹³C₆ solutions and high-resolution mass spectrometry and ESI-tandem MS/MS spectrometry techniques, the occurrence of glucose oxidation products, for example, aldonic acids and aldaric acids, glucono- and glucaro-lactones, as well as less abundant sugar acids including ribonic acid, arabinuronic acid, oxoadipic acid, 3-deoxy-ribose, glutaconic acid, and glucic acid were surveyed. The findings provide deep insights into CAP chemistry, reflecting a switch of reactive species generation with the feed gas modulation (Ar or Ar/O₂ with N₂ curtain gas). Depending on the gas phase composition, a combination of oxygen-derived short-lived hydroxyl (^•OH)/atomic oxygen [O(³P)] radicals was found responsible for the glucose oxidation cascade. The results further illustrate that the presence of carbohydrates in cell culture media, gel formulations (agar), or other liquid targets (juices) modulate the availability of CAP-generated species in vitro. In addition, a glycocalyx is attached to many mammalian proteins, which is essential for the respective physiologic role. It might be questioned if its oxidation plays a role in CAP activity.

Heat Shock Protein 27 Affects Myeloid Cell Activation and Interaction with Prostate Cancer Cells

Heat shock proteins are cytoprotective molecules induced by environmental stresses. The small heat shock protein 27 (Hsp27) is highly expressed under oxidative stress conditions, mediating anti-oxidative effects and blocking apoptosis. Since medical gas plasma treatment subjects cancer cells to a multitude of reactive oxygen species (ROS), inducing apoptosis and immunomodulation, probable effects of Hsp27 should be investigated. To this end, we quantified the extracellular Hsp27 in two prostate cancer cell lines (LNCaP, PC-3) after gas plasma-induced oxidative stress, showing a significantly enhanced release. To investigate immunomodulatory effects, two myeloid cell lines (THP-1 and HL-60) were also exposed to Hsp27. Only negligible effects on viability, intracellular oxidative milieu, and secretion profiles of the myeloid cells were found when cultured alone. Interestingly, prostate cancer-myeloid cell co-cultures showed altered secretion profiles with a significant decrease in vascular endothelial growth factor (VEGF) release. Furthermore, the myeloid surface marker profiles were changed, indicating an enhanced differentiation in co-culture upon Hsp27 treatment. Finally, we investigated morphological changes, proliferation, and interaction with prostate cancer cells, and found significant alterations in the myeloid cells, supporting the tendency to differentiate. Collectively, our results suggest an ambiguous effect of Hsp27 on myeloid cells in the presence of prostate cancer cells which needs to be further investigated.

Non-thermal plasma elicits ferrous chloride-catalyzed DMPO-OH

Non-thermal plasma (NTP) induces the generation of reactive oxygen species (ROS) and reactive nitrogen species, such as hydroxyl radicals (^•OH), hydrogen peroxide (H₂O₂), singlet oxygen, superoxide, ozone, and nitric oxide, at near-physiological temperatures. These molecules promote blood coagulation, wound healing, disinfection, and selective cancer cell death. Based on these evidences, clinical trials of NTP have been conducted for treating chronic wounds and head and neck cancers. Although clinical applications have progressed, the stoichiometric quantification of NTP-induced ROS remains unclear in the liquid phase in the presence of FeCl₂ or FeCl₃ in combination with biocompatible reducing agents, which may modulate the final biological effects of NTP. In this study, we employed electron paramagnetic resonance spectroscopy to quantify ROS using spin-trapping probe, 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) and H₂O₂, using luminescent probe in the presence of FeCl₂ or FeCl₃. NTP-induced DMPO-OH levels were elevated 10-100 µM FeCl₂ or 500 and 1000 µM FeCl₃. NTP-induced DMPO-OH with 10 µM FeCl₂ or FeCl₃ was significantly scavenged by ascorbate, α-tocopherol, dithiothreitol, reduced glutathione, or oxidized glutathione, whereas dehydroascorbate was ineffective in 2 mM DMPO. NTP-induced H₂O₂ was significantly degraded by 100 µM FeCl₂ and FeCl₃ in an iron-dependent manner. Meanwhile, decomposition of H₂O₂ by catalase decayed DMPO-OH efficiently in the presence of iron, indicating iron causes DMPO-OH production and degradation simultaneously. These results suggest that NTP-induced DMPO-OH is generated by the H₂O₂-consuming, iron-dependent Fenton reaction and ferryl intermediates. The potential iron-mediated ROS production by NTP is also discussed to clarify the interaction between NTP-induced ROS and biomolecules.

Non-invasive medical gas plasma augments bladder cancer cell toxicity in preclinical models and patient-derived tumor tissues

INTRODUCTION

Medical gas plasma therapy has been successfully applied to several types of cancer in preclinical models. First palliative tumor patients suffering from advanced head and neck cancer benefited from this novel therapeutic modality. The gas plasma-induced biological effects of reactive oxygen and nitrogen species (ROS/RNS) generated in the plasma gas phase result in oxidation-induced lethal damage to tumor cells.

OBJECTIVES

This study aimed to verify these anti-tumor effects of gas plasma exposure on urinary bladder cancer.

METHODS

2D cell culture models, 3D tumor spheroids, 3D vascularized tumors grown on the chicken chorion-allantois-membrane (CAM) in ovo, and patient-derived primary cancer tissue gas plasma-treated ex vivo were used.

RESULTS

Gas plasma treatment led to oxidation, growth retardation, motility inhibition, and cell death in 2D and 3D tumor models. A marked decline in tumor growth was also observed in the tumors grown in ovo. In addition, results of gas plasma treatment on primary urothelial carcinoma tissues ex vivo highlighted the selective tumor-toxic effects as non-malignant tissue exposed to gas plasma was less affected. Whole-transcriptome gene expression analysis revealed downregulation of tumor-promoting fibroblast growth factor receptor 3 (FGFR3) accompanied by upregulation of apoptosis-inducing factor 2 (AIFm2), which plays a central role in caspase-independent cell death signaling.

CONCLUSION

Gas plasma treatment induced cytotoxicity in patient-derived cancer tissue and slowed tumor growth in an organoid model of urinary bladder carcinoma, along with less severe effects in non-malignant tissues. Studies on the potential clinical benefits of this local and safe ROS therapy are awaited.

The potential of gas plasma technology for targeting breast cancer

Despite therapeutic improvements in recent years, breast cancer remains an often fatal disease. In addition, breast cancer ulceration may occur during late stages, further complicating therapeutic or palliative interventions. In the past decade, a novel technology received significant attention in the medical field: gas plasma. This topical treatment relies on the partial ionization of gases that simultaneously produce a plethora of reactive oxygen and nitrogen species (ROS/RNS). Such local ROS/RNS overload inactivates tumour cells in a non-necrotic manner and was recently identified to induce immunogenic cancer cell death (ICD). ICD promotes dendritic cell maturation and amplifies antitumour immunity capable of targeting breast cancer metastases. Gas plasma technology was also shown to provide additive toxicity in combination with radio and chemotherapy and re-sensitized drug-resistant breast cancer cells. This work outlines the assets of gas plasma technology as a novel tool for targeting breast cancer by summarizing the action of plasma devices, the roles of ROS, signalling pathways, modes of cell death, combination therapies and immunological consequences of gas plasma exposure in breast cancer cells in vitro, in vivo, and in patient-derived microtissues ex vivo.

Electronic effects on the mechanism of the NAD+ coenzyme reduction catalysed by a non-organometallic ruthenium(ii) polypyridyl amine complex in the presence of formate

In the present study, electronic effects on the mechanism of the NAD⁺ coenzyme reduction in the presence of formate, catalysed by a non-organometallic ruthenium(ii) polypyridyl amine complex, were investigated. The [Ru^II(terpy)(ampy)Cl]Cl (terpy = 2,2′:6′,2′′-terpyridine, ampy = 2-(aminomethyl)pyridine) complex was employed as the catalyst. The reactions were studied in a water/ethanol mixture as a function of formate, catalyst, and NAD⁺ concentrations at 37 °C. The overall process was found to be 11 to 18 times slower than for the corresponding ethylenediamine (en) complex as the result of π-back bonding effects of the ampy ligand. The mechanistic studies revealed a complete set of reactions that accounted for the overall catalytic cycle based on a formate-induced hydride transfer reaction to form the reduced coenzyme, NADH. The geometries of the ruthenium(ii)-ampy complexes involved in the catalytic cycle and free energy changes for the main steps were predicted by DFT calculations. Similar calculations were also performed for the analogues ruthenium(ii)-en and ruthenium(ii)-bipy complexes (bipy = 2,2′-bipyridine). The DFT calculated energies show that both the solvent-formato exchange and the formato-hydrido conversion reactions have negative (favourable) energies to proceed spontaneously. The reactions involving the en complex have the more negative (favourable) reaction energies, followed by the ampy complex, in agreement with faster reactions for en complexes and slower reactions for bipy complexes than for ampy complexes.

The graphical abstract represents the overall catalytic cycle in which the non-organometallic Ru(ii) formato complex releases CO₂ and transfers hydride to NAD⁺ to form NADH coenzyme.

Immunostimulation in experimental gas plasma therapy for breast cancer

Gas plasma is a partially ionized gas operated at body temperature, expelling various reactive oxygen species (ROS) in chorus. While the technology's anticancer potential is generally appreciated, exciting progress in experimental gas plasma therapy for breast cancer has been made recently, particularly in empowering anticancer immunity.

Cold atmospheric pressure plasma treatment combined with starvation increases autophagy and apoptosis in melanoma in vitro and in vivo

Despite advances in therapy, malignant melanoma remains a fatal disease. Among several emerging approaches to combat cancer, cold atmospheric pressure plasma (CAP) has shown promising results as a novel antitumor agent in preclinical models so far. The technology mainly relies on the emittance of various reactive oxygen and nitrogen species (ROS/RNS) that are tumor-toxic at high concentrations. Moreover, malignant melanoma has a metabolic dimension that can be targeted by mild starvation. To this end, we investigated the combined effect of starvation and CAP treatment on melanoma in vitro and in vivo. In vitro, starvation+CAP led to cell morphology changes, decreased metabolic activity and increased lipid peroxidation accompanied by apoptosis and DNA fragmentation in murine B16 melanoma cells but not murine non-malignant L929 fibroblasts. This was paralleled by increased apoptosis (Bax, Bcl-2 and Caspase-3) and autophagy (Lc3 and Atg5)-related gene expression. In vivo, starvation reduced tumor burden. Combination with CAP treatment augmented this effect significantly, albeit there was no difference of combination treatment to CAP exposure alone. Interestingly, there was an overall greater increase of Lc3 and Atg5 in the tumor tissue compared to CAP exposure alone, while starvation-induced autophagy-related gene expression was similar to in the combination group. These data collectively suggest that CAP-derived ROS/RNS treatment and autophagy-induction augment antitumor effects in malignant melanoma in vitro and in vivo.

Cold Argon Athmospheric Plasma for Biomedicine: Biological Effects, Applications and Possibilities

Currently, plasma medicine is a synthetic direction that unites the efforts of specialists of various profiles. For the successful formation of plasma medicine, it is necessary to solve a large complex of problems, including creating equipment for generating cold plasma, revealing the biological effects of this effect, as well as identifying and justifying the most promising areas of its application. It is known that these biological effects include antibacterial and antiviral activity, the ability to stimulate hemocoagulation, pro-regenerative properties, etc. The possibility of using the factor in tissue engineering and implantology is also shown. Based on this, the purpose of this review was to form a unified understanding of the biological effects and biomedical applications of argon cold plasma. The review shows that cold plasma, like any other physical and chemical factors, has dose dependence, and the variable parameter in this case is the exposure of its application. One of the significant characteristics determining the specificity of the cold plasma effect is the carrier gas selection. This gas carrier is not just an ionized medium but modulates the response of biosystems to it. Finally, the perception of cold plasma by cellular structures can be carried out by activating a special molecular biosensor, the functioning of which significantly depends on the parameters of the medium (in the field of plasma generation and the cell itself). Further research in this area can open up new prospects for the effective use of cold plasma.

Human Trial for the Effect of Plasma-Activated Water Spray on Vaginal Cleaning in Patients with Bacterial Vaginosis

Underwater plasma discharge temporally produces several reactive radicals and/or free chlorine molecules in water, which is responsible for antimicrobial activity. Hence, it can simply sanitize tap water without disinfectant treatment. Additionally, the spraying technique using cleaning water exploits deep application in the narrow and curved vaginal tract of patients. Herein, we attempted a clinical trial to evaluate the vaginal cleaning effect of spraying plasma-activated water (PAW) to patients with vaginitis (46 patients). The efficacy was compared with treatment with betadine antiseptics used to treat bacterial vaginosis (40 patients). To evaluate the cleaning effect, Gram staining of the vaginal secretions was conducted before and after spraying PAW or betadine treatment (BT). Consequently, PAW-sprayed (PAWS) patients (22.3%) showed a better vaginal cleaning effect against Gram-positive and -negative bacteria than BT patients (14.4%). Moreover, 18 patients in the BT group showed worsened vaginal contamination, whereas five patients in the PAWS group showed worsened vaginal contamination. Taken together, the noncontact method of spraying cleaning water to the vagina exhibited a reliable vaginal cleaning effect without further bacterial infection compared with BT. Therefore, we suggest a clinical application of the spraying method using PAW for vaginal cleaning to patients with vaginitis without disinfectants and antibiotics.

Inhibitory Effects of Cold Atmospheric Plasma on Inflammation and Tumor-Like Feature of Fibroblast-Like Synoviocytes from Patients with Rheumatoid Arthritis

Rheumatoid arthritis (RA) is a chronic, debilitating systemic disease characterized by chronic inflammation and progressive joint destruction. Fibroblast-like synoviocytes (FLSs) are one of the most important players in the pathophysiology of RA, acting like tumor cells and secreting inflammatory cytokines. Previous research has shown that cold atmospheric plasma (CAP) inhibits cancer cells and may have anti-inflammatory properties. This study examined the effects of argon plasma jet-produced CAP on the suppression of invasion and inflammation caused by cultured RA-FLS. The findings revealed that CAP reduced cell viability and elevated the percentage of apoptotic RA-FLS by producing reactive oxygen species. Carboxyfluorescein diacetate succinimidyl ester (CFSE) staining confirmed that CAP could decrease the proliferation of RA-FLS. Furthermore, CAP effectively reduced the production of inflammatory factors (e.g., NF-κB and IL-6) as well as destructive factors like receptor activator of nuclear factor kappa-B ligand (RANKL) and matrix metalloproteinases-3 (MMP-3). These data suggest that CAP could be a promising treatment for slowing the progression of RA by reducing tumor-like features and inflammation in RA-FLS.

Changing Perspectives from Oxidative Stress to Redox Signaling-Extracellular Redox Control in Translational Medicine

Extensive research has changed the understanding of oxidative stress that has been linked to every major disease. Today we distinguish oxidative eu- and distress, acknowledging that redox modifications are crucial for signal transduction in the form of specific thiol switches. Long underestimated, reactive species and redox proteins of the Thioredoxin (Trx) family are indeed essential for physiological processes. Moreover, extracellular redox proteins, low molecular weight thiols and thiol switches affect signal transduction and cell–cell communication. Here, we highlight the impact of extracellular redox regulation for health, intermediate pathophenotypes and disease. Of note, recent advances allow the analysis of redox changes in body fluids without using invasive and expensive techniques. With this new knowledge in redox biochemistry, translational strategies can lead to innovative new preventive and diagnostic tools and treatments in life sciences and medicine.

Low-intensity cold atmospheric plasma reduces wrinkles on photoaged skin through hormetic induction of extracellular matrix protein expression in dermal fibroblasts

BACKGROUND

Recent evidence indicates that cold atmospheric plasma (CAP) can upregulate the production of extracellular matrix (ECM) proteins in dermal fibroblasts and enhance transdermal drug delivery when applied at a low intensity.

OBJECTIVES

The aim of this study was to evaluate the effect of low-intensity CAP (LICAP) on photoaging-induced wrinkles in an animal model and the expression profiles of ECM proteins in human dermal fibroblasts.

METHODS

Each group was subjected to photoaging induction and allocated to therapy (LICAP, topical polylactic acid (PLA), or both). The wrinkles were evaluated via visual inspection, quantitative analysis, and histology. The expression of collagen I/III and fibronectin was assessed using reverse transcription-quantitative polymerase chain reaction, western blot analysis, and immunofluorescence. The amount of aqueous reactive species produced by LICAP using helium and argon gas was also measured.

RESULTS

Wrinkles significantly decreased in all treatment groups compared to those in the untreated control. The differences remained significant for at least 4 weeks. Dermal collagen density increased following LICAP and PLA application. LICAP demonstrated a hormetic effect on ECM protein expression in human dermal fibroblasts. The production of reactive species increased, showing a biphasic pattern, with an initial linear phase and a slow saturation phase. The initial linearity was sustained for a longer time in the helium plasma (~60 s) than in the argon plasma (~15 s).

CONCLUSION

LICAP appears to be a novel treatment option for wrinkles on the photodamaged skin. This treatment effect seems to be related to its hormetic effect on dermal ECM production.

Enhanced growth factor expression in chronic diabetic wounds treated by cold atmospheric plasma

AIMS

Cold atmospheric plasma (CAP) has been proven to enhance wound healing in superficial, chronically infected, diabetic foot ulcers. We aimed to investigate the molecular drivers responsible for this macroscopically observed improvement in diabetic wound healing.

METHODS

Wound exudate was available from each change of dressing within a prospective, randomised, patient-blinded clinical trial. Specific protein level analyses were conducted via multiplex ELISA for wound samples of a representative subcohort (placebo: n = 13; CAP: n = 14). Expression of fibroblast growth factor 2 (FGF-2), vascular endothelial growth factor A (VEGF-A), cytokines and matrix metalloproteinases (MMPs) were evaluated over a treatment period of about 14 days.

RESULTS

Analysis revealed increased levels of the growth factors FGF-2 (placebo: median 46.9 range [32.0-168.6] AU vs. CAP: 113.7[55.8-208.1] AU) and VEGF-A (placebo: 79.7 [52.4-162.7] AU vs. CAP: 120.8 [51.1-198.1] AU) throughout the treatment period and in head-to-head comparison in a daily assessment. CAP-treated wounds showed increased levels of tumour necrosis factor-alpha, interleukins 1α and 8. However, the total protein amounts were not significantly elevated. The total protein amounts of MMPs were not altered by CAP.

CONCLUSIONS

Induction of crucial growth factors, like FGF-2 and VEGF-A, and interleukins appears to be an important component of CAP-mediated promotion of granulation, vascularisation and reepithelialisation in the diabetic foot. These findings demonstrate for the first time that CAP-mediated growth factor induction also occurs in persons with diabetes, as previously described only in several in vitro and rodent experiments. Clinical Trial registration KPWTRIAL: NCT04205942, ClinicalTrials.gov.

Flucytosine-based prodrug activation by cold physical plasma

Reactive oxygen species (ROS) are known to trigger drug release from arylboronate-containing ROS-responsive prodrugs. In cancer cells, elevated levels of ROS can be exploited for the selective activation of prodrugs via Baeyer-Villiger type oxidation rearrangement sequences. Here, we report a proof of concept to demonstrate that these cascades can as well be initiated by cold physical plasma (CPP). An analog of a recently reported fluorouracil prodrug based on the less toxic drug 5-fluorocytosine (5-FC) was synthesized with a view to laboratory safety reasons and used as a model compound to prove our hypothesis that CPP is suitable as a trigger for the prodrug activation. Although the envisioned oxidation and rearrangement with successive loss of boronic acid species could be achieved by plasma treatment, the anticipated spontaneous liberation of 5-FC was inefficient in the model case. However, the obtained results suggest that custom-tailored CPP-responsive prodrugs might become an evolving research field.

Non-Thermal Plasma Jet-Treated Medium Induces Selective Cytotoxicity against Mycobacterium tuberculosis-Infected Macrophages

Plasma-treated media (PTM) serve as an adjuvant therapy to postoperatively remove residual cancerous lesions. We speculated that PTM could selectively kill cells infected with Mycobacterium tuberculosis (Mtb) and remove postoperative residual tuberculous lesions. We therefore investigated the effects of a medium exposed to a non-thermal plasma jet on the suppression of intracellular Mtb replication, cell death, signaling, and selectivity. We propose that PTM elevates the levels of the detoxifying enzymes, glutathione peroxidase, catalase, and ataxia-telangiectasia mutated serine/threonine kinase and increases intracellular reactive oxygen species production in Mtb-infected cells. The bacterial load was significantly decreased in spleen and lung tissues and single-cell suspensions from mice intraperitoneally injected with PTM compared with saline and untreated medium. Therefore, PTM has the potential as a novel treatment that can eliminate residual Mtb-infected cells after infected tissues are surgically resected.

Therapeutic Effects of Cold Atmospheric Plasma on Solid Tumor

Cancer is a devastating disease, and there is no particularly effective treatment at present. Recently, a new treatment, cold atmospheric plasma (CAP), has been proposed. At present, CAP is confirmed to have selective killing effect on tumor by many studies in vitro and in vivo. A targeted literature search was carried out on the study of cold atmospheric plasma. Through analysis and screening, a narrative review approach was selected to describe therapeutic effects of cold atmospheric plasma on solid tumor. According to the recent studies on plasma, some hypothetical therapeutic schemes of CAP are proposed in this paper. The killing mechanism of CAP on solid tumor is expounded in terms of the selectivity of CAP to tumor, the effects of CAP on cells, tumor microenvironment (TME) and immune system. CAP has many effects on solid tumors, and these effects are dose-dependent. The effects of optimal doses of CAP on solid tumors include killing tumor cells, inhibiting non-malignant cells and ECM in TME, affecting the communication between tumor cells, and inducing immunogenic death of tumor cells. In addition, several promising research directions of CAP are proposed in this review, which provide guidance for future research.

Pathways of organic micropollutants degradation in atmospheric pressure plasma processing - A review

Concern of toxic compounds and their, potentially more harmful degradation products, present in aquatic environment alarmed scientific community and research on the development of novel technologies for wastewater treatment had become of great interest. Up to this date, many papers pointed out the challenges and limitations of conventional wastewater treatment and of some advanced oxidation processes. Advanced technologies based on the use of non-equilibrium or non-thermal plasma had been recognized as a possible solution for, not only degradation, but for complete removal of recalcitrant organic micropollutants. While previous review papers have been focused on plasma physics and chemistry of different types of discharges for few organic micropollutants, this paper brings comprehensive review of current knowledge on the chemistry and degradation pathways by using different non-thermal plasma types for several micropollutants' classes, such as pharmaceuticals, perfluorinated compounds, pesticides, phenols and dyes and points out some major research gaps.