Plasma Medicine

Plasma treatment is a promising technology for fast and effective sterilization of surfaces, waterflow, and airflow. The treatment of airflow is an important area of healthcare and biodefense that has recently gained the interest of many scientists. In this paper, we describe a dielectric barrier grating discharge (DBGD) which is used to study the inactivation of airborne Escherichia coli inside a closed air circulation system. Earlier published results indicate approximately 5-log reduction (99.999%) in the concentration of the airborne bacteria after single DBGD exposure of 10-s duration. This paper investigates plasma species influencing the inactivation. The two major factors that are studied are the effect of charged and short-lived species (direct exposure to plasma) and the effect of ozone. It is shown that for a 25% reduction in direct exposure, the inactivation falls from 97% to 29% in a single pass through the grating. The influence of ozone was studied by producing ozone remotely with an ozone generator and injecting the same concentration into the system, as that produced by the DBGD plasma. The results show a 10% reduction in the bacterial load after 10-s exposure to ozone; thus, ozone alone may not be one of the major inactivating factors in the plasma.

Nonthermal plasmas (NTPs) represent a perspective class of antibacterial agents that might be an alternative to chemical disinfectants because they possess an unspecific antimicrobial activity and can be applied to decontamination of heat-and chemical-sensitive surfaces as well as to the infected skin and wounds. The resistance to NTP depends on properties of both a microorganism and a certain plasma source. Two bacterial species, Pseudomonas aeruginosa and Staphylococcus aureus, which are among the most important causative agents of nosocomial infections, were tested with three different plasma sources. The ferroelectric air plasma generator, the microwave argon plasma source, and the generator of a positive and negative corona discharge in air demonstrated increasing activity toward tested bacteria. The relative resistance of the tested strains to NTPs produced by distinct plasma sources differed. P. aeruginosa was more resistance to the corona discharge and less resistant to the plasma generated by the ferroelectric generator than S. aureus while both strains demonstrated comparable resistance to microwave argon plasma. Obtained results demonstrated a role of charged particles as a primary factor in the high effectiveness of the positive and negative coronas and an importance of the NO• radical among neutral active species.

As a result of both the better understanding of complex plasma phenomena and the development of new plasma sources in the past few years, plasma medicine has developed into an innovative field of research showing high potential. While thermal plasmas have long been used in various medical fields (for instance for cauterization and sterilization of medical instruments), current research mainly focuses on application of non-thermal plasmas. Experiments show that cold atmospheric plasmas (CAPs) allow efficient, contact-free and painless disinfection, even in microscopic openings, without damaging healthy tissue. Plasmas influence biochemical processes and offer new possibilities for the selective application of individually designable medically active substances. In dermatology, new horizons are being opened for wound healing, tissue regeneration, therapy of skin infections, and probably many more diseases. First clinical trials show the efficacy and tolerability of plasma in treating infected chronic wounds. A major task will be the introduction of plasma into clinical medicine and, simultaneously, the further investigation of the mechanisms of action of plasma at the cellular level. Figure 2: The plasma torch (MicroPlaSter ␤ ® ; 2.45 GHz, 86 W, Ar 2.2 slm) as an example of an indirect plasma source: Plasma is generated at the 6 electrodes and then transported to the target area via gas flow. The torch itself has to be cooled by air flow. 6 Review Article Plasma medicine JDDG | 2010 (Band 8)

A direct current, cold, atmospheric-pressure Ar/O 2 (2%) plasma microjet (PMJ) was used to disinfect root canals in single-rooted extracted human teeth. Results showed that 98.8% Enterococcus faecalis (E. faecalis) was inactivated in 8 min. However, the seemingly cleaned root canal was reinfected after a week, possibly due to the hard-to-reach infected dentinal tubules. It was found that a 30-min PMJ treatment could effectively prevent the reinfection. This presents a simple yet effective alternative to traditional treatment of root canal infections in endodontic therapy. KEY WORDS: plasma microjet, root canal, disinfection Volume 1, Number 2, 2011 The Effect of an Atmospheric Pressure, DC Nonthermal Plasma Microjet on Tooth Root Canal, Dentinal Tubules Infection and Reinfection Prevention

Cold atmospheric pressure plasmas were previously shown in vitro to be effective in generating active species, radicals, and charges which may aid in various processes of interest to medicine, including blood coagulation. This manuscript confirms cold plasma’s ability to coagulate blood in a live animal model. A small incision in rat ear, cutting the thin epidermis and slicing through the capillaries in the ear, creates a small and controllable wound where bleeding is observed. Without plasma treatment the animal bleeds for approximately 2 minutes while a 10 second treatment is sufficient to coagulate blood.

Keywords: cold plasma, non-thermal plasma, dielectric barrier discharge, floating electrode, blood coagulation, animal model, rat, plasma medicine

Chinese researchers may have found a new approach to treat cancer by using a plasma treatment to induce apoptosis, the death of cancer cells, without any obvious side effect to normal cells. [45] Physicists of Ruhr-Universität Bochum (RUB) have taken spectacular pictures that allow the ignition process of plasma under water to be viewed and tracked in real time. [44] Laser-produced high energy density plasmas, akin to those found in stars, nuclear explosions, and the core of giant planets, may be the most extreme state of matter created on Earth. [43]

A direct-current cold atmospheric-pressure air plasma microjet (PMJ) based on the microhollow cathode discharge design is used to inactivate six types of bacteria within a small well-defined area on a large petri dish. We show that the PMJ is very effective in inactivating bacteria in their vegetative state as well as in the spore state within the area of plasma exposure. We also observed that bacteria in their vegetative state were inactivated efficiently outside the area of direct plasma exposure. Different bacteria responded differently to an increase in the plasma exposure (dose). Lastly, we observed two types of colony forming unit (CFU) distributions after plasma treatment; one distribution is diffusionlike with a gradual increase of the surviving CFU as one moves radially away from the area of direct plasma exposure, and the other distribution shows an essentially uniform reduction in surviving CFU across the entire petri dish.

Helmut Sies established the concept of oxidative stress in 1985.
However, it took some time to introduce this concept into
pathology, where investigators count on formalin-fixed
paraffin-embedded tissue sections. I sought out antigens for
this purpose based on an oxidative stress-induced rat renal
carcinogenesis model, which revealed that 8-hydroxy-2′-
deoxyguanosine and 4-hydroxy-2-nonenal-modified proteins
are ideal. These two monoclonal antibodies successfully
revealed the involvement of oxidative stress in numerous human diseases, including carcinogenesis and atherosclerosis.
Shigeru Okada established the aforementioned ferric
nitrilotriacetate (Fe-NTA)-induced rat renal carcinogenesis
model, which thus far has answered many questions regarding
the presence of target genes in oxidative stress-induced carcinogenesis and the sites that are susceptible to oxidative stress in the genome. Particularly, the similarity of genomic alterations between Fe-NTA-induced renal cancer and human cancers suggests that excess iron plays a role also inhuman carcinogenesis. Furthermore, excess iron is amajor pathology in asbestosinduced mesothelioma, including chrysotile. Despite an analogy to asbestos, multi-wall carbon nanotubes were distinct in that diameter is another responsible factor for mesothelial carcinogenesis. Recently, non-thermal plasma emerged as a candidate for medical intervention for wounds and cancers via manipulating oxidative stress. Counteracting excess iron is a promising preventive strategy for major diseases.

Increasing process complexity and consumer demands for less processed goods has led to strong demand for new effective decontamination methods. Therefore, atmospheric tial for diverse decontamination applications. The aim of this work was to investigate the anof food products after packaging. The approach was tested under both static and continuous modes of treatment against pathogenic microorganisms Escherichia coli and Listeria innocua impact of treatment on produce quality during extended shelf life was also evaluated. Greater than 5 log reductions of E. coli population density surface attached on tomatoes was achieved in 150 s of treatment generated during either static or continuous operational mode. L. innocua be achieved in tandem with quality retention using a pilot scale system in which the mode of operation was optimized for cherry tomato as a representative fresh product.

Purpose: Medical plasma application has been used in different fields recently. In this study, we assess the outcome of using plasma-assisted noninvasive surgery (PANIS) with amniotic membrane transplantation (AMT) in pterygium surgical treatment. Methods: This clinical case series was conducted in 4 patients with primary grades 1, 2, and 3 pterygium (Table 1). After exclusion and inclusion criteria considerations, patients underwent different examinations. Various measurements were obtained such as uncorrected visual acuity (UCVA), refractive error (RE), the best-corrected visual acuity (BCVA), and ocular surface disease index (OSDI). The surgical procedure was pterygium removal from the cornea and then AMT attached to the conjunctival borders with plasma spots using a white handpiece of Plexr device (Plexr, GMV s.r.l Grottaferrata, Italy) instead (Table 2). After postoperative follow-ups within the first week of the surgery and in 1 month and 6 months later the results were obtained. Results: All patients have been fully recovered after the surgery without any complications. In all 4 cases, UCVA, BCVA, and RE parameters have improved during 6 months after the surgical procedure. Every patients' OSDI decreased after the surgery. Recurrence has not been seen in any cases during 6 months follow-up. Conclusion: Pterygium removal surgery using the PANIS technique with AMT is safe, effective, fast, and cost-benefit.

This paper reports the generation of cold plasma jet working under atmospheric pressure condition, for surface treatment of polymeric films. The discharge has been characterized by electrical and optical methods. The electrical property of the discharge has been studied by taking current-voltage wave forms using voltage and current probes. The production of argon plasma jet is done in atmospheric conditions which are relatively much cheaper, convenient, and safer to use. The atmospheric pressure plasma jet sustained in pure argon has been used to improve wettability of polypropylene (PP). Cold atmospheric pressure plasma jet (CAPPJ) has been generated by a high-voltage power supply (5.5 kV, 0-20 kV) at an operating frequency of 20 kHz. The surface properties of the controls and plasma-treated PP samples were characterized by contact angle measurement, surface free energy measurement, scanning electron microscopy, and the Fourier transform-infrared spectroscopy analysis.

Several variations of dielectric barrier discharge (DBD) have been developed for nondamaging living-tissue sterilization and blood coagulation. This so-called floating electrode DBD (FE-DBD) has been shown by histology to not damage the treated tissue. Nevertheless, preliminary experiments show that a person who touches the FE-DBD can feel the discharge action. Some of these unpleasant sensations are related to the thermal effects of the plasma. These thermal effects and other important parameters of the discharge are strongly dependent on the electrical properties of the discharge, i.e., driving voltage and waveform shape. In this paper, we first employed sinusoidal driving waveform for medical applications. After that, in order to increase the uniformity and decrease the temperature, we employed a microsecond-pulsed waveform system with a few microsecond pulse durations. Both plasma systems have been analyzed and compared for thermal effects and temperature of the discharge in order to determine the possibilities to control the heating effect with driving waveform.

A tooth-whitening process using hydrogen peroxide (H 2 O 2 ) enhanced by a direct-current cold atmospheric-pressure plasma microjet (PMJ) is presented. Compared with the conventional clinical method of using H 2 O 2 alone, a significant improvement of the tooth-whitening process was observed when the PMJ was used in the process. The tooth-surface temperature was monitored for safety considerations and did not exceed 37 • C at a distance of 1 cm between the exit nozzle of the plasma source and the tooth for a treatment time of 20 min. No apparent differences in the tooth-surface morphology and microhardness were observed between teeth treated with and without the PMJ. The use of the PMJ with H 2 O 2 resulted in an enhanced production of reactive hydroxyl (OH) radicals. This plasma-enhanced tooth-whitening method may be a promising new method for clinical applications.

Octafluorocyclobutane and acrylic acid (C 4 F 8-co-AA) are plasma copolymerized onto low-density polyethylene (LDPE) and glass slides under various pulsation periods of radio frequency pulsed plasma. The surface wettability of plasma polymer coating is traditionally considered as a substrate-independent property. The combined effect of ultra-thin C 4 F 8-co-AA coatings and LDPE substrate on surface wettability is presented. The high concentration of the carboxylic acid functional groups gives rise to hydrophilicity via lowering duty cycle, and substrate impact gives rise to hydrophobicity for ultrathin coatings. The X-ray photoelectron spectroscopy and coating thickness measurements confirmed that the sudden increase in water contact angle for the lower duty cycle is influenced by the hydrophobic substrate for ultrathin polymer coatings. It is highlighted that the precise control over the surface wettability is attained by tuning the plasma parameters. The substrate-dependent wettability for flat substrate persisted for longer than 8 weeks, which demonstrates wetting stability for ultrathin coatings.

As a result of both the better understanding of complex plasma phenomena and the development of new plasma sources in the past few years, plasma medicine has developed into an innovative field of research showing high potential. While thermal plasmas have long been used in various medical fields (for instance for cauterization and sterilization of medical instruments), current research mainly focuses on application of non-thermal plasmas. Experiments show that cold atmospheric plasmas (CAPs) allow efficient, contact-free and painless disinfection, even in microscopic openings, without damaging healthy tissue. Plasmas influence biochemical processes and offer new possibilities for the selective application of individually designable medically active substances. In dermatology, new horizons are being opened for wound healing, tissue regeneration, therapy of skin infections, and probably many more diseases. First clinical trials show the efficacy and tolerability of plasma in treating infected chronic wounds. A major task will be the introduction of plasma into clinical medicine and, simultaneously, the further investigation of the mechanisms of action of plasma at the cellular level. Figure 2: The plasma torch (MicroPlaSter ␤ ® ; 2.45 GHz, 86 W, Ar 2.2 slm) as an example of an indirect plasma source: Plasma is generated at the 6 electrodes and then transported to the target area via gas flow. The torch itself has to be cooled by air flow. 6 Review Article Plasma medicine JDDG | 2010 (Band 8)

Titanium and titanium alloys are widely considered successful biocompatible materials because titanium implants become easily connected, both structurally and functionally, to biological systems. Antibacterial activity for medical implants could be an interesting property to prevent inflammation of the implant site. In this study, cold plasma treatments were performed on a titanium surface and the antibacterial activity of treated samples was tested against Escherichia coli 32. Some plasma parameters were varied to find the best antibacterial conditions. Samples showing higher germicidal activity were obtained in several experimental set-ups, and the antibacterial activity was detected at same level 16 days after the plasma treatment. A correlation between antibacterial effect and plasma-treated titanium surface energy also was studied.

The authors report a new nanosecond-pulsed dielectric-barrier discharge (DBD) for sterilization and other medical applications. In the literature, several discharges have been reported, with pulse durations on the order of hundreds of nanoseconds. In this paper, a novel pulsed DBD has been developed, with only few tens of nanosecond pulsewidths working uniformly over large range of electrode gap distance in air under atmospheric pressure.

Atmospheric Pressure Plasma (APP) is being used widely in a variety of biomedical applications. Extensive research in the field of plasma medicine has shown the induction of DNA damage by APP in a dose-dependent manner in both prokaryotic and eukaryotic systems. Recent evidence suggests that APP-induced DNA damage shows potential benefits in many applications, such as sterilization and cancer therapy. However, in several other applications, such as wound healing and dentistry, DNA damage can be detrimental. This review reports on the extensive investigations devoted to APP interactions with DNA, with an emphasis on the critical role of reactive species in plasma-induced damage to DNA. The review consists of three main sections dedicated to fundamental knowledge of the interactions of reactive oxygen species (ROS)/reactive nitrogen species (RNS) with DNA and its components, as well as the effects of APP on isolated and cellular DNA in prokaryotes and eukaryotes.

Abstract: Atmospheric pressure non-equilibrium (cold) plasmas are already known to be effective sterilization agents. This work further confirms the ability of cold plasma to inactivate pathogenic organisms in a live animal model. The rat wound model used here represents a surgical treatment situation whereby the wound is open and the bleeding is controlled. High concentration of Staphylococcus aureus is placed onto the wound area and allowed to incubate for two hours prior to cold plasma treatment. We show a 3-log reduction in pathogen load on the wound following a one minute treatment.

Keywords: cold plasma, non-thermal plasma, dielectric barrier discharge, floating electrode, sterilization, animal model, rat, plasma medicine

The authors report a new nanosecond-pulsed dielectric-barrier discharge (DBD) for sterilization and other medical applications. In the literature, several discharges have been reported, with pulse durations on the order of hundreds of nanoseconds. In this paper, a novel pulsed DBD has been developed, with only few tens of nanosecond pulsewidths working uniformly over large range of electrode gap distance in air under atmospheric pressure.

—Bacillus spores represent one of the most resistant organisms to conventional sterilization methods. This paper is focused on the inactivation of the spores of two Bacillus species, Bacillus cereus and Bacillus anthracis, using atmospheric-pressure dielectric-barrier-discharge (DBD) plasma. Spores treated in liquid or air-dried on a solid surface were effectively inactivated within 1 min of DBD plasma treatment at a discharge power of 0.3 W/cm 2. Results of a series of model experiments show that neutral reactive oxygen species and UV radiation play a dominant role in the inactivation of spores. We also show that 45 s of the DBD plasma treatment of air-dried spores placed inside closed plastic or paper envelopes permits up to 7 log reduction of viable spores. Index Terms—Anthrax, atmospheric-pressure dielectric barrier discharge (DBD), Bacillus anthracis, nonequilibrium plasma, non-thermal plasma, spore inactivation, sterilization.

This paper reports the generation of cold plasma jet working under atmospheric pressure condition, for surface treatment of polymeric films. The discharge has been characterized by electrical and optical methods. The electrical property of the discharge has been studied by taking current-voltage wave forms using voltage and current probes. The production of argon plasma jet is done in atmospheric conditions which are relatively much cheaper, convenient, and safer to use. The atmospheric pressure plasma jet sustained in pure argon has been used to improve wettability of polypropylene (PP). Cold atmospheric pressure plasma jet (CAPPJ) has been generated by a high-voltage power supply (5.5 kV, 0-20 kV) at an operating frequency of 20 kHz. The surface properties of the controls and plasma-treated PP samples were characterized by contact angle measurement, surface free energy measurement, scanning electron microscopy, and the Fourier transform-infrared spectroscopy analysis.

We reported in this paper the tooth-whitening effect by a direct-current cold atmospheric-pressure air plasma microjet (PMJ) and saline solution (0.9%). All teeth were randomly divided into three groups, treated for 20 min with an air blow and saline solution, a PMJ and saline solution, and 35% hydrogen peroxide gel, respectively. Compared with the other groups, the teeth treated with the PMJ and saline solution showed the best tooth-whitening effect. The microhardness of the tooth enamel measurement showed no apparent differences among the three groups. A minor enamel surface morphological change was observed via SEM but was considered acceptable. Singlet oxygen ( 1 O 2 ) and hydroxyl ( • OH) radicals were detected by electron spin resonance spectroscopy. Atomic oxygen (O) was observed in the optical emission spectra of the PMJ. 1 O 2 , • OH, and O were considered to be the key agents during the tooth-whitening process. This novel method of tooth whitening has the potential to revolutionize the clinical tooth-whitening procedure.

Developing arrays of parallel microplasma jets is an attractive route to scaling the area available
for the treatment of surfaces with low temperature plasma. Increasing the packing density of the
arrays may lead to electrical and gas kinetic jet–jet interactions, but previous work has focused
almost exclusively on electrostatic coupling between the jets. Chemical interactions (‘crosstalk’)
have received considerably less attention. We report here the results of an investigation
of chemical crosstalk in 4 × 4 arrays of microplasma jets, produced in flowing helium at
atmospheric pressure. Oxidation damage to an Escherichia coli lawn serves as a diagnostic of
the spatial distribution of molecular radicals and other reactive plasma species, produced at the
plasma jet/ambient background interface or between the jets, and incident on the surface. Spatial
maps of bacterial inactivation by the microplasma jet array for 20s show the destruction of E. coli
at distances as large as 2.7 jet diameter from the nearest plasma perimeter, compared to typically
less than 0.5 jet diameter in the single jet case. Extending to 30s of plasma exposure leads to
destruction of the entire bacterial sample. This ‘action at a distance’ effect, the production of longlived
species such as O, O2(a1
Δg) and O3 that are responsible for bacterial deactivation, peaks
along a line bisecting columns and rows of plasma jets. The data illustrate the synergistic effect of
adjacent jets on off-axis formation of reactive species, and show that the chemical and biological
impact of an array cannot be inferred from the plasma chemistry of a single jet.

A microhollow cathode based, direct-current, atmospheric pressure, He/ O 2 ͑2%͒ cold plasma microjet was used to inactive antifungal resistants Candida albicans, Candida krusei, and Candida glabrata in air and in water. Effective inactivation ͑Ͼ90%͒ was achieved in 10 min in air and 1 min in water. Antifungal susceptibility tests showed drastic reduction of the minimum inhibitory concentration after plasma treatment. The inactivation was attributed to the reactive oxygen species generated in plasma or in water. Hydroxyl and singlet molecular oxygen radicals were detected in plasma-water system by electron spin resonance spectroscopy. This approach proposed a promising clinical dermatology therapy.

Recent research in plasma biology proved that atmospheric pressure plasma jets (APPJs) have a biocidal effect, making them a promising alternative to traditional antimicapability of the APPJs, the streamer propagation, and the chemistry involved. The aim of this study is to investigate experimentally the effect of the target conductivity on the plasma characteristics: plasma jet propagation and reactive species production. The results show that the tions depend on the conductivity of the target. The results also demonstrate that the generation This study shows that the assessment of RONS generated by APPJs should be performed as close as possible to the real applications conditions.

The aim of this paper is to investigate the effect of nonthermal atmospheric pressure plasma jet on human breast cancer and normal cells. High voltage, dc-pulsed power supply was used to generate low temperature helium plasma in atmospheric pressure. In this paper, cancer and normal cells were exposed to plasma during four time steps. For further exploration, Doxorubicin as common chemotherapy drug was employed to compare the efficacy of plasma treatment with convectional cancer therapy. Also, the Caspase-Glo 3/7 assay was obtained to reveal the death process of cancer and normal cells. The results of MTT and apoptosis assay showed that the plasma treatment has drastically reduced the viability of breast cancer cells, while it has no significant damage to the normal cells. In addition, after plasma treatment three different zones were formed in the plate, which will represent the detachment of cells from plate surface. Moreover, adding 5% oxygen to the helium plasma will lead to enhancement of cancer cells viability reduction. In addition, the outcome of this paper has verified that the plasma treatment successfully overcomes drug treatment in inhibition of the cancer cells viability, while decreases the adverse effect of drug treatment.

He directs activities of the Magnetic Microsystems Laboratory and is a member of the Drexel Plasma Institute. His current research interests include magnetically programmed self-assembly, magnetic separation in biotechnology, magnetically targeted drug delivery, magnetic tweezing as a tool for investigation of living cells, design and fabrication of microcoils for nuclear magnetic resonance spectroscopy, and imaging of live cells and modeling of hysteresis in magnetic systems and complex networks. He is also interested in the development of cold atmospheric pressure plasma technology for applications in biotechnology and medicine.

A direct-current cold atmospheric-pressure air plasma microjet (PMJ) based on the microhollow cathode discharge design is used to inactivate six types of bacteria within a small well-defined area on a large petri dish. We show that the PMJ is very effective in inactivating bacteria in their vegetative state as well as in the spore state within the area of plasma exposure. We also observed that bacteria in their vegetative state were inactivated efficiently outside the area of direct plasma exposure. Different bacteria responded differently to an increase in the plasma exposure (dose). Lastly, we observed two types of colony forming unit (CFU) distributions after plasma treatment; one distribution is diffusionlike with a gradual increase of the surviving CFU as one moves radially away from the area of direct plasma exposure, and the other distribution shows an essentially uniform reduction in surviving CFU across the entire petri dish.

Non-thermal atmospheric-pressure plasmas have been developed that will be used in future for several purposes, e.g. medicine. Living tissues and cells are at the focus of plasma treatment, e.g. to improve wound healing, or induce apoptosis and growth arrest in tumour cells. Detailed investigations of plasma-cell interactions are needed. Cell surface adhesion molecules as integrins, cadherins or the EGFR (epidermal growth factor receptor) are of importance in wound healing and also for development of cancer metastasis. This study has focused on measurement of cell surface molecules on human HaCaT keratinocytes (human adult low calcium temperature keratinocytes) promoting adhesion, migration and proliferation as one important feature of plasma-cell interactions. HaCaT keratinocytes were treated with plasma by a surface dielectric barrier discharge in air. Cell surface molecules and induction of intracellular ROS (reactive oxygen species) were analysed by flow cytometry 24 h after plasma treatment. Besides a reduction of cell viability a significant down-regulation of Ecadherin and the EGFR expression occurred. The influence on a 2 -and b 1 -integrins was less pronounced, and expression of ICAM-1 (intercellular adhesion molecule 1) was unaffected. The extent of effects depended on the exposure time of cells to the plasma and the treatment regimen. Intracellular level of ROS detected by the fluorescent dye H 2 DCFDA (29,79dichlorodihydrofluorescein diacetate) increased by plasma treatment, but it was neither dependent on the treatment time nor related to the different treatment regimens. Two-dimensional cultures of HaCaT keratinocytes appear to be a suitable method of investigating plasma-cell interactions.

Plasma medicine is a novel, highly interdisciplinary field of research. Although the knowledge is rare concerning plasma based biomedical mechanisms, correct dosages and treatment times, animal experiments have been carried out. To follow the 3Rs (reduction, refinement, replacement), it is necessary to define methods for the screening of plasma parameters.

The antimicrobial effects of the cold plasma for the dental pathogenic microorganism propose a promising approach to the Denture Stomatitis (DS) treatment. However, it is crucial to understand that the complexity of the biofilm microenvironment may compromise the efficiency of the therapy. As one of the major issue for DS, Candida albicans biofilms (ATCC10231) formed on denture base resins were treated by cold Ar/O2 (2 %) plasma jet. Spatial viability of the biofilms was investigated with confocal scanning laser microscopy through evaluating their inside cross-section properties. Results showed Candida albicans biofilms with thickness of ~100 µm was completely inactivated by 8 min plasma treatment. Morphology change of the fungi was also observed by the scanning electron microscopy. Drug susceptibilities, the sessile minimum inhibitory concentration (SMIC50) of the biofilm for amphotericin B and fluconazole were decreased from >32 and >256 µg/mL to 8 and 64 µg/mL after 1 min’s plasma treatment, respectively. The reactive species produced from plasma were monitored by optical emission spectroscopy. The successfully inactivation of Candida albicans biofilms and the significant enhancement of its drug susceptibilities induced by the plasma released reactive species propose a promising strategy for the treatment of DS caused by drug-resistant Candida albicans biofilms.

Atmospheric Dielectric Barrier Discharge (DBD) plasma development is one of the most interesting subjects to our group. Fridman et al. * has concluded that Floating DBD Direct Plasma are more effective in bactericidal property, it contains higher free charged particles than indirect type. DBD plasma sources can provide low temperature or non-thermal (cold) plasmas, and these plasmas can be created with ambient air or with a noble gas, such as helium or argon, as the carrier medium. It can be used with an electrode as a contact or noncontact method to target a tissue. However, the drawback of direct DBD plasma is that it will work only in short gap distances, on the order of a few millimeters. Our group has investigated-PLASMA Cell Modulation: PhotoBioCare, Thailand). The major area has been focused on its bactericidal disinfection property, application in common dermatologic problems, in skin aesthetic facial rejuvenation and chronic wound management, from 2012 to 2016.