Gregory Fridman

Atmospheric pressure non-equilibrium plasmas are efficacious in killing both prokaryotic and eukaryotic cells. While the mechanism of plasma induced cell death has been thoroughly studied in prokaryotes, detailed investigation of plasma mediated eukaryotic cell death is still pending. When plasma is generated, four major components that interact with cells are produced: electric fields, radiation, charged particles, and neutral gas species. The goal of this study was to determine which of the… Show more

Atmospheric pressure non-equilibrium plasmas are efficacious in killing both prokaryotic and eukaryotic cells. While the mechanism of plasma induced cell death has been thoroughly studied in prokaryotes, detailed investigation of plasma mediated eukaryotic cell death is still pending. When plasma is generated, four major components that interact with cells are produced: electric fields, radiation, charged particles, and neutral gas species. The goal of this study was to determine which of the plasma components are responsible for plasma-induced cell death by isolating and removing each from treatment. The C3H10T1/2 murine mesenchyme stem cell line was treated in six well plates, stained with Propidium Iodide to determine viability, and analyzed by image cytometry. Our results show that plasma-generated charges and reactive oxygen species are the primary contributors to cell death. Show less

Plasma has been shown to be effective against cancer cells both in vitro and in vivo. Several studies have documented the selectivity of plasma against cancer cells with minimal or reduced damage to normal cells. However, complete remission of cancer following plasma treatment has not been achieved yet. In the body, the immune system plays a vital role in the prevention and control of cancer. Presence of cells of the adaptive immune system in the tumor microenvironment is usually an indicator… Show more

Plasma has been shown to be effective against cancer cells both in vitro and in vivo. Several studies have documented the selectivity of plasma against cancer cells with minimal or reduced damage to normal cells. However, complete remission of cancer following plasma treatment has not been achieved yet. In the body, the immune system plays a vital role in the prevention and control of cancer. Presence of cells of the adaptive immune system in the tumor microenvironment is usually an indicator of good prognosis. Since immune cell migration is a key initial step towards defense against diseases, it is important to evaluate the influence of plasma treatment on such cellular functions. Here we show that treatment with nanosecond-pulsed non-thermal dielectric barrier discharge enhances migration of macrophages in vitro. Show less

Enhancing chondrogenic and osteogenic differentiation is of paramount importance in providing effective regenerative therapies and improving the rate of fracture healing. This study investigated the potential of non-thermal atmospheric dielectric barrier discharge plasma (NT-plasma) to enhance chondrocyte and osteoblast proliferation and differentiation. Although the exact mechanism by which NT-plasma interacts with cells is undefined, it is known that during treatment the atmosphere is ionized… Show more

Enhancing chondrogenic and osteogenic differentiation is of paramount importance in providing effective regenerative therapies and improving the rate of fracture healing. This study investigated the potential of non-thermal atmospheric dielectric barrier discharge plasma (NT-plasma) to enhance chondrocyte and osteoblast proliferation and differentiation. Although the exact mechanism by which NT-plasma interacts with cells is undefined, it is known that during treatment the atmosphere is ionized generating extracellular reactive oxygen and nitrogen species (ROS and RNS) and an electric field. Appropriate NT-plasma conditions were determined using lactate-dehydrogenase release, flow cytometric live/dead assay, flow cytometric cell cycle analysis, and Western blots to evaluate DNA damage and mitochondrial integrity. We observed that specific NT-plasma conditions were required to prevent cell death, and that loss of pre-osteoblastic cell viability was dependent on intracellular ROS and RNS production. To further investigate the involvement of intracellular ROS, fluorescent intracellular dyes Mitosox (superoxide) and dihydrorhodamine (peroxide) were used to assess onset and duration after NTplasma treatment. Both intracellular superoxide and peroxide were found to increase immediately post NT-plasma treatment. ...//... However, treatment of cells with NT-plasma after 24 hr in osteogenic or chondrogenic media significantly enhanced differentiation as compared to differentiation media alone. The results of this study show that NT-plasma can selectively initiate and amplify ROS signaling to enhance differentiation, and suggest this technology could be used to enhance bone fusion and improve healing after skeletal injury. Show less

This paper demonstrates plasma bullets generated by microsecond pulses in He flow propagation inside of conductive agarose gel tubes mimicking tissue. The objective of this paper is to understand the possibility of internal diseases’ treatment (e.g., lung or intestinal cancer) using plasma jets. The propagation dynamics is studied using fast imaging technique, and production of reactive species is demonstrated both in gas phase (using optical emission spectroscopy) and inside of the agarose gel… Show more

This paper demonstrates plasma bullets generated by microsecond pulses in He flow propagation inside of conductive agarose gel tubes mimicking tissue. The objective of this paper is to understand the possibility of internal diseases’ treatment (e.g., lung or intestinal cancer) using plasma jets. The propagation dynamics is studied using fast imaging technique, and production of reactive species is demonstrated both in gas phase (using optical emission spectroscopy) and inside of the agarose gel (using fluorescent dye). In addition, it is demonstrated that plasma bullets may propagate not only in a straight tubes, but also in L-shaped tubes, as well as be split in T-shaped tubes. All these facts offer an indication of possible successful application of plasma bullets for treatment of internal diseases, for example, lung cancers or intestinal diseases. Show less

By applying dielectric-barrier discharge nonthermal plasma technique, we have treated fluids and generated antimicrobial solutions, tested for properties such as changes in pH, temperature, delay time, holding time, fluid-aging, and detection and comparison of acid and hydrogen peroxide. All plasma-treated solutions showed strong biocidal activity, and among them, NAC solution was the most powerful, inactivated biofilms of tested microorganisms in 15 min of holding time. During accelerated… Show more

By applying dielectric-barrier discharge nonthermal plasma technique, we have treated fluids and generated antimicrobial solutions, tested for properties such as changes in pH, temperature, delay time, holding time, fluid-aging, and detection and comparison of acid and hydrogen peroxide. All plasma-treated solutions showed strong biocidal activity, and among them, NAC solution was the most powerful, inactivated biofilms of tested microorganisms in 15 min of holding time. During accelerated aging experiments, plasma-treated NAC solution exhibited the equivalent of two years of shelf. These results indicate that it retained its antimicrobial properties for an extended period against a wide range of multidrug-resistant pathogens, making it an excellent candidate for further testing in vivo. Show less

Thermal plasma is a valued tool in surgery for its coagulative and ablative properties. We suggested through in vitro studies that nonthermal plasma can sterilize tissues, inactive pathogens, promote coagulation, and potentiate wound healing. The present research was undertaken to study acute toxicity in porcine skin tissues.We demonstrate that floating electrode-discharge barrier discharge (FE-DBD) nonthermal plasma is electrically safe to apply to living organisms for short periods. We… Show more

Thermal plasma is a valued tool in surgery for its coagulative and ablative properties. We suggested through in vitro studies that nonthermal plasma can sterilize tissues, inactive pathogens, promote coagulation, and potentiate wound healing. The present research was undertaken to study acute toxicity in porcine skin tissues.We demonstrate that floating electrode-discharge barrier discharge (FE-DBD) nonthermal plasma is electrically safe to apply to living organisms for short periods. We investigated the effects of FE-DBD plasma on Yorkshire pigs on intact and wounded skin immediately after treatment or 24 h posttreatment. Macroscopic or microscopic histological changes were identified using histological and immunohistochemical techniques. The changes were classified into four groups for intact skin: normal features, minimal changes or congestive changes, epidermal layer damage, and full burn and into three groups for wounded skin: normal, clot or scab, and full burn-like features. Immunohistochemical staining for laminin layer integrity showed compromise over time. A marker for doublestranded DNA breaks, g-H2AX, increased over plasma-exposure time. These findings identified a threshold for plasma exposure of up to 900 s at low power and <120 s at high power. Nonthermal FE-DBD plasma can be considered safe for future studies of external use under these threshold conditions for evaluation of sterilization, coagulation, and wound healing. Show less

Water quality, mineralization, and chemical composition, particularly pH and nitrogen compounds each, play a crucial role in plant development and growth. Treatment of water with non-equilibrium discharges results in the change of its properties and chemical composition, which in turn may affect plant growth process and subsequently agriculture produce quality. Both thermal and non-thermal discharges generated in air or in water produce a number of reactive neutral and charged species, electric… Show more

Water quality, mineralization, and chemical composition, particularly pH and nitrogen compounds each, play a crucial role in plant development and growth. Treatment of water with non-equilibrium discharges results in the change of its properties and chemical composition, which in turn may affect plant growth process and subsequently agriculture produce quality. Both thermal and non-thermal discharges generated in air or in water produce a number of reactive neutral and charged species, electric fields, and ultraviolet radiation. Plasma treatment of water results in significant change of its properties like pH, oxidation/reduction potential (ORP), conductivity, and concentration of reactive oxygen and reactive nitrogen species (ROS and RNS). Here we report the results of an experimental study of the effect of water treated with different atmospheric plasmas on germination, growth rates, and overall nutritional value of various plants. In the study we have used three types of plasmas: thermal spark discharge, gliding arc discharge, and transferred arc discharge. It is shown that the effects of these plasmas on chemical composition of various types of water are qualitatively different. Non-thermal gliding arc discharge plasma results in lower (acidic) pH, and production of significant amount of oxidizing species (e.g. H2O2). Gliding arc discharge also causes significant acidification of water, but it is accompanied by production of reactive nitrogen species (NO, NO2- and NO3-?). Spark discharge treatment results in neutral or higher (basic) pH depending on initial water composition, and production of RNS. Show less

In this article we present an in vitro model based on agarose gel that can be used to simulate a dirty, oily, bloody, and morphologically complex surface of, for example, an open wound. We show this model’s effectiveness in simulating the depth of penetration of reactive species generated in plasma (e.g., hydrogen peroxide) deep into the tissue of a rat and confirm the penetration depths using an agarose gel model. We envision that such a model could be used in the future to study plasma… Show more

In this article we present an in vitro model based on agarose gel that can be used to simulate a dirty, oily, bloody, and morphologically complex surface of, for example, an open wound. We show this model’s effectiveness in simulating the depth of penetration of reactive species generated in plasma (e.g., hydrogen peroxide) deep into the tissue of a rat and confirm the penetration depths using an agarose gel model. We envision that such a model could be used in the future to study plasma discharges (and other modalities) and minimize the use of live animals; plasma can be optimized on the agarose gel wound model and then finally verified using an actual wound. Show less

The whole blood viscosity (WBV) is one of the major independent indicators for the risk of cardiovascular disease, stroke, and peripheral arterial diseases. Furthermore, oxidized LDL molecules are known to cause atherosclerotic plaques in arteries, and it is one of the key components that increase WBV. The present study attempted to reduce WBV by coagulating plasma proteins and lipid molecules from blood plasma using nonthermal dielectric barrier discharge (DBD) and removing them through… Show more

The whole blood viscosity (WBV) is one of the major independent indicators for the risk of cardiovascular disease, stroke, and peripheral arterial diseases. Furthermore, oxidized LDL molecules are known to cause atherosclerotic plaques in arteries, and it is one of the key components that increase WBV. The present study attempted to reduce WBV by coagulating plasma proteins and lipid molecules from blood plasma using nonthermal dielectric barrier discharge (DBD) and removing them through filtration. The DBD treatment was found to produce coagulated particles in blood plasma. After filtration of the coagulated particles, WBV decreased by 9.1 and 17.7% for both systolic and diastolic blood viscosities, respectively. The present results suggest that the removal of excess plasma proteins and lipid molecules might be feasible using DBD treatment. Show less

Nonthermal plasma has been shown to be effective in reducing pathogens on the surface of a range of fresh produce products. The research presented here investigated the effectiveness of nonthermal dielectric barrier discharge plasma on Salmonella enterica and Campylobacter jejuni inoculated onto the surface of boneless skinless chicken breast and chicken thigh with skin. Chicken samples were inoculated with antibiotic-resistant strains of S. enterica and C. jejuni at levels of 101 to 104 CFU… Show more

Nonthermal plasma has been shown to be effective in reducing pathogens on the surface of a range of fresh produce products. The research presented here investigated the effectiveness of nonthermal dielectric barrier discharge plasma on Salmonella enterica and Campylobacter jejuni inoculated onto the surface of boneless skinless chicken breast and chicken thigh with skin. Chicken samples were inoculated with antibiotic-resistant strains of S. enterica and C. jejuni at levels of 101 to 104 CFU and exposed to plasma for a range of time points (0 to 180 s in 15-s intervals). Surviving antibiotic-resistant pathogens were recovered and counted on appropriate agar. In order to determine the effect of plasma on background microflora, noninoculated skinless chicken breast and thighs with skin were exposed to air plasma at ambient pressure. Treatment with plasma resulted in elimination of low levels (101 CFU) of both S. enterica and C. jejuni on chicken breasts and C. jejuni from chicken skin, but viable S. enterica cells remained on chicken skin even after 20 s of exposure to plasma. Inoculum levels of 102, 103, and 104 CFU of S. enterica on chicken breast and chicken skin resulted in maximum reduction levels of 1.85, 2.61, and 2.54 log, respectively, on chicken breast and 1.25, 1.08, and 1.31 log, respectively, on chicken skin following 3 min of plasma exposure. Inoculum levels of 102, 103, and 104 CFU of C. jejuni on chicken breast and chicken skin resulted in maximum reduction levels of 1.65, 2.45, and 2.45 log, respectively, on chicken breast and 1.42, 1.87, and 3.11 log, respectively, on chicken skin following 3 min of plasma exposure. Plasma exposure for 30 s reduced background microflora on breast and skin by an average of 0.85 and 0.21 log, respectively. This research demonstrates the feasibility of nonthermal dielectric barrier discharge plasma as an intervention to help reduce foodborne pathogens on the surface of raw poultry. Show less

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 four hours prior to cold plasma treatment. We… Show more

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 four hours prior to cold plasma treatment. We show a 3-log reduction in pathogen load on the wound following a one minute treatment. Show less

Cold plasma discharges have been shown to have medically-relevant therapeutic
effects when applied to living tissues, including blood coagulation and wound healing;
thus, plasma treatment of infl amed tissues in ulcerative colitis disease may be an effective approach
to reduce adverse consequences if not cure the disease. Here we discuss results of the
fi rst experimental study of cold plasma treatment of ulcerative colitis in a mouse model. As a
plasma source, a cold spark… Show more

Cold plasma discharges have been shown to have medically-relevant therapeutic
effects when applied to living tissues, including blood coagulation and wound healing;
thus, plasma treatment of infl amed tissues in ulcerative colitis disease may be an effective approach
to reduce adverse consequences if not cure the disease. Here we discuss results of the
fi rst experimental study of cold plasma treatment of ulcerative colitis in a mouse model. As a
plasma source, a cold spark discharge has been used. The results show that plasma treatment
of experimental model of ulcerative colitis in mice has some benefi cial effects by suppressing
the progression of the disease while no damage to colon tissues is observed; and these effects
are comparable to standard therapy. Show less

We show data indicating that resonance-Raman spectroscopy can distinguish live Escherichia coli bacteria from E. coli killed by a nanosecond-pulsed dielectric barrier discharge. The observations may result in an in situ, real-time method of monitoring sterilization efficacy.

Cold atmospheric pressure plasmas previously have been shown to be effective in vitro in generating active species, radicals, and charges, which may aid in various processes of interest to medicine, including blood coagulation. Floating electrode dielectric barrier discharge microsecond-pulsed, high-voltage plasma was used in an animal model of hairless Sprague-Dawley rats to treat an incision on the ear. The results confirm cold plasma’s ability to coagulate blood in a live animal model. A… Show more

Cold atmospheric pressure plasmas previously have been shown to be effective in vitro in generating active species, radicals, and charges, which may aid in various processes of interest to medicine, including blood coagulation. Floating electrode dielectric barrier discharge microsecond-pulsed, high-voltage plasma was used in an animal model of hairless Sprague-Dawley rats to treat an incision on the ear. The results confirm cold plasma’s ability to coagulate blood in a live animal model. A small incision in the rat ear, cutting the thin epidermis and slicing through the capillaries, creates a small and controllable wound from which bleeding is observed. Without plasma treatment, the animal bleeds for approximately 2 minutes, whereas a 10-second treatment is sufficient to coagulate blood. Cold plasma floating electrode dielectric barrier discharge was shown to effectively coagulate bleeding small vessels, which may prove beneficial in surgical intervention treatments of, for example, vocal cord surgery, eye surgery, or brain surgery, for which other means of coagulation may be prohibitive. Future animal trials will include larger animals and different bleeding sites, with the potential to move on to human trials. Show less

When injected directly into spinal tissue, poly(lactide-co-glycolide) (PLGA) particles have the potential to provide sustained delivery of proteins necessary to promote nerve regeneration. To ensure the injection of sterile particles, a novel decontamination method was developed that can inactivate bacteria while maintaining particle and protein integrity. This method involves the resuspension of protein-loaded particles after preparation in phosphate-buffered saline (PBS) or deionized water… Show more

When injected directly into spinal tissue, poly(lactide-co-glycolide) (PLGA) particles have the potential to provide sustained delivery of proteins necessary to promote nerve regeneration. To ensure the injection of sterile particles, a novel decontamination method was developed that can inactivate bacteria while maintaining particle and protein integrity. This method involves the resuspension of protein-loaded particles after preparation in phosphate-buffered saline (PBS) or deionized water that has been subjected to a nonthermal atmospheric pressure discharge. Although different treatment times were required, it was demonstrated that both plasma-treated PBS and water can completely inactivate Escherichia coli when added at a concentration of 103 colony-forming units/mL to PLGA particles with and without protein. Plasma-treated water showed no impact on particle morphology. Plasma treatment of water for 1 minute resulted in the complete sterilization of protein-loaded particles but was able to maintain only 26.6 ± 5.0% of protein activity. On the other hand, plasma-treated PBS required 2 minutes of treatment for complete sterilization of protein-loaded particles but was able to maintain 68.4 ± 10.6% of protein activity. Particles were considered sterile if no bacterial growth was observed after being plated onto bacterial growth agar. The effect of plasma-treated water on release of active protein from particles caused a substantial loss in the initial burst release of protein but did not limit the ability of the particles to provide a sustained release of active protein. Show less

Oxidative stress leads to membrane lipid peroxidation, which yields products causing variable degrees of detrimental oxidative modifications in cells. Reactive oxygen species (ROS) are the key regulators in this process and induce lipid peroxidation in Escherichia coli. Application of nonthermal (cold) plasma is increasingly used for inactivation of surface contaminants. Recently, we reported a successful application of nonthermal plasma, using a floating-electrode dielectric-barrier discharge… Show more

Oxidative stress leads to membrane lipid peroxidation, which yields products causing variable degrees of detrimental oxidative modifications in cells. Reactive oxygen species (ROS) are the key regulators in this process and induce lipid peroxidation in Escherichia coli. Application of nonthermal (cold) plasma is increasingly used for inactivation of surface contaminants. Recently, we reported a successful application of nonthermal plasma, using a floating-electrode dielectric-barrier discharge (FE-DBD) technique for rapid inactivation of bacterial contaminants in normal atmospheric air (S. G. Joshi et al., Am. J. Infect. Control 38:293–301, 2010). In the present report, we demonstrate that FE-DBD plasma-mediated inactivation involves membrane lipid peroxidation in E. coli. Dose-dependent ROS, such as singlet oxygen and hydrogen peroxide-like species generated during plasma-induced oxidative stress, were responsible for membrane lipid peroxidation, and ROS scavengers, such as ?-tocopherol (vitamin E), were able to significantly inhibit the extent of lipid peroxidation and oxidative DNA damage. These findings indicate that this is a major mechanism involved in FE-DBD plasma-mediated inactivation of bacteria. Show less

Observations of atmospheric-pressure dielectric barrier discharge are conducted through a waterfilled electrode in atmospheric-pressure argon gas flow. Quasi-symmetric self-organized discharge filaments were observed. The streamers moved with the gas flow, and the migration velocity increased with increasing gas velocity.

Background: Bacterial contamination of surfaces with methicillin-resistant Staphylococcus aureus (MRSA) is a serious problem in the hospital environment and is responsible for significant nosocomial infections. The pathogenic contaminants form biofilms, which are difficult to treat with routine biocides. Thus, a continuous search for novel disinfection methods is essential for effective infection control measures. This demonstration of a novel technique for the control of virulent pathogens in… Show more

Background: Bacterial contamination of surfaces with methicillin-resistant Staphylococcus aureus (MRSA) is a serious problem in the hospital environment and is responsible for significant nosocomial infections. The pathogenic contaminants form biofilms, which are difficult to treat with routine biocides. Thus, a continuous search for novel disinfection methods is essential for effective infection control measures. This demonstration of a novel technique for the control of virulent pathogens in planktonic form as well as in established biofilms may provide a progressive alternative to standard methodology.
Methods: We evaluated a novel technique of normal atmospheric nonthermal plasma known as floating-electrode dielectric-barrier discharge (FE-DBD) plasma against a control of planktonic and biofilm forms of Escherichia coli, S aureus, multidrug-resistant methicillin- resistant S aureus (MRSA) -95 (clinical isolate), -USA300, and -USA400, using widely accepted techniques such as colony count assay, LIVE/DEAD BacLight Bacterial Viability assay, and XTT (2,3-Bis(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide) assay.
Results: Exposure of free living planktonic forms of E coli, S aureus, and MRSA were rapidly inactivated by DBD plasma. Approximately 107 bacterial cells were completely (100%) killed, whereas 108 and 109 were reduced by approximately 90% to 95% and 40% to 45%, respectively, in less than 60 seconds (7.8 J/cm2) and completely disinfected in#120 seconds. In established biofilms, the susceptibility of MRSA USA400 was comparable with USA300 but less susceptible than MRSA95 (clinical isolate), S aureus, and E coli (P , .05) to FE-DBD plasma, and plasma was able to kill MRSA more than 60% within 15 seconds (1.95 J/cm2). The killing responses were plasma exposure-time dependent, and cell density dependent. The plasma was able disinfect surfaces in a less than 120 seconds. Show less

Aims: Dielectric barrier discharge (DBD) plasma is used for sterilization of contaminated inanimate surfaces but seldomly optimized and depends upon the type of organisms and the plasma treatment duration, (net energy deposited) this efficacy varies. The proposed study was designed to see biological responses of one of the robust organism, Bacillus stratosphericus.
Methods and Results: DBD plasma was applied over various durations to B. stratosphericus either surface-dried or suspension in… Show more

Aims: Dielectric barrier discharge (DBD) plasma is used for sterilization of contaminated inanimate surfaces but seldomly optimized and depends upon the type of organisms and the plasma treatment duration, (net energy deposited) this efficacy varies. The proposed study was designed to see biological responses of one of the robust organism, Bacillus stratosphericus.
Methods and Results: DBD plasma was applied over various durations to B. stratosphericus either surface-dried or suspension in de-ionized water, and viability, culturability, and viable but nonculturability (VBNC) were assayed using standard techniques. Depending upon the exposure of B. stratosphericus to DBD plasma resulted in three viability states, viable and culturable at low plasma doses and VBNC or disintegrated bacteria at higher plasma doses. Although organism’s respiration levels at relatively low levels, immediately after plasma treatment, over the course of 24- h respiratory activity was increased c. eight times (and found still nonculturable during colony assays).
Conclusions: The loss of culturability is hypothesized to be induced as one of the responses to oxidative stress and it remains to be unclear if the response is temporary or indefinite. Appropriate plasma powers should be used to avoid VBNC-like status. 2,3-Bis-(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide (XTT) assay is a good alternative method to detect VBNC state.
Significance and Impact of the Study: Bacillus stratosphericus has the potential to turn into VBNC upon plasma application, and XTT assay can be an alternative method to detect VBNC state. Show less

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/cm2. Results of a series of model experiments show… Show more

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/cm2. 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. Show less

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… Show more

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. Show less

Antimicrobial effectiveness of a nanosecond-pulsed dielectric barrier discharge (DBD) was investigated and compared with that of a microsecond-pulsed DBD. Experiments were conducted on the Escherichia coli bacteria covering a topographically non-uniform agar surface acting as one of the DBD electrodes. They reveal that the nanosecond-pulsed DBD can inactivate bacteria in recessed areas whereas the microsecond-pulsed and conventional DBDs fail to do so. Charged species (electrons and ions)… Show more

Antimicrobial effectiveness of a nanosecond-pulsed dielectric barrier discharge (DBD) was investigated and compared with that of a microsecond-pulsed DBD. Experiments were conducted on the Escherichia coli bacteria covering a topographically non-uniform agar surface acting as one of the DBD electrodes. They reveal that the nanosecond-pulsed DBD can inactivate bacteria in recessed areas whereas the microsecond-pulsed and conventional DBDs fail to do so. Charged species (electrons and ions) appear to play the major role in the bacteria inactivation with the nanosecond-pulsed DBD. Moreover, the nanosecond-pulsed DBD kills bacteria significantly faster than its microsecond-pulsed counterpart. Show less

We showed that nonthermal dielectric barrier discharge (DBD) plasma compromises the integrity of the cell membrane of Deinococcus radiodurans, an extremophile organism. In samples of D. radiodurans, which were dried in a laminar flow hood, we observe that DBD plasma exposure resulted in a six-log reduction in CFU (colony-forming unit) count after 30 min of treatment.When the Deinococcus radiodurans cells were suspended in distilled water and treated, it took only 15 s to achieve a four-log… Show more

We showed that nonthermal dielectric barrier discharge (DBD) plasma compromises the integrity of the cell membrane of Deinococcus radiodurans, an extremophile organism. In samples of D. radiodurans, which were dried in a laminar flow hood, we observe that DBD plasma exposure resulted in a six-log reduction in CFU (colony-forming unit) count after 30 min of treatment.When the Deinococcus radiodurans cells were suspended in distilled water and treated, it took only 15 s to achieve a four-log reduction of CFU count. Show less

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… Show more

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. Show less

Mechanisms of plasma interaction with living tissues and cells can be quite complex, owing to the complexity of both the plasma and the tissue. Thus, unification of all the mechanisms under one umbrella might not be possible. However, the authors are attempting to make first steps in this direction. In this paper, analysis of interaction of floating electrode dielectric barrier discharge (FE-DBD) with living tissues and cells is presented and biological and physical mechanisms are discussed. In… Show more

Mechanisms of plasma interaction with living tissues and cells can be quite complex, owing to the complexity of both the plasma and the tissue. Thus, unification of all the mechanisms under one umbrella might not be possible. However, the authors are attempting to make first steps in this direction. In this paper, analysis of interaction of floating electrode dielectric barrier discharge (FE-DBD) with living tissues and cells is presented and biological and physical mechanisms are discussed. In physical mechanisms, charged species are identified as the major contributors to the desired effect and a mechanism of this interaction is proposed. Biological mechanisms are also addressed and a hypothesis of plasma selectivity and its effects is offered. Show less

An emerging field of plasma medicine is discussed, where non-equilibrium plasmas are shown to be able to initiate, promote, control, and catalyze various complex behaviors and responses in biological systems. More importantly, it will be shown that plasma can be tuned to achieve the desired medical effect, especially in medical sterilization and treatment of different kind of skin diseases. Wound healing and tissue regeneration can be achieved following various types of plasma treatment in a… Show more

An emerging field of plasma medicine is discussed, where non-equilibrium plasmas are shown to be able to initiate, promote, control, and catalyze various complex behaviors and responses in biological systems. More importantly, it will be shown that plasma can be tuned to achieve the desired medical effect, especially in medical sterilization and treatment of different kind of skin diseases. Wound healing and tissue regeneration can be achieved following various types of plasma treatment in a multitude of wound pathologies. Non-equilibrium plasmas will be shown to be non-destructive to tissue, safe, and effective in inactivation of various parasites and foreign organisms. Show less

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 pulse widths working uniformly over large range of electrode gap distance in air under atmospheric pressure.

The drug-eluting stent’s increasingly frequent occurrence late stage thrombosis have created a need for new strategies for intervention in coronary artery disease. This paper demonstrates further development of our minimally invasive, targeted drug delivery system that uses induced magnetism to administer repeatable and patient specific dosages of therapeutic agents to specific sites in the human body. Our first aim is the use of magnetizable stents for the prevention and treatment of coronary… Show more

The drug-eluting stent’s increasingly frequent occurrence late stage thrombosis have created a need for new strategies for intervention in coronary artery disease. This paper demonstrates further development of our minimally invasive, targeted drug delivery system that uses induced magnetism to administer repeatable and patient specific dosages of therapeutic agents to specific sites in the human body. Our first aim is the use of magnetizable stents for the prevention and treatment of coronary restenosis; however, future applications include the targeting of tumors, vascular defects, and other localized pathologies. Future doses can be administered to the same site by intravenous injection. This implant-based drug delivery system functions by placement of a weakly magnetizable stent or implant at precise locations in the cardiovascular system, followed by the delivery of magnetically susceptible drug carriers. The stents are capable of applying high local magnetic field gradients within the body, while only exposing the body to a modest external field. The local gradients created within the blood vessel create the forces needed to attract and hold drug-containing magnetic nanoparticles at the implant site. Once these particles are captured, they are capable of delivering therapeutic agents such as antineoplastics, radioactivity, or biological cells. Show less

Direct and indirect influence on microorganisms of non-thermal atmospheric-pressure DBD in air is compared in terms of bacterial inactivation rates. It is demonstrated that direct influence of the plasma, where charged particles contact bacteria directly, produces inactivation much faster than the indirect treatment, where plasma afterglow is delivered to the bacteria with a gas flow through the plasma region. This leads to an important conclusion that the effect of charged particles on plasma… Show more

Direct and indirect influence on microorganisms of non-thermal atmospheric-pressure DBD in air is compared in terms of bacterial inactivation rates. It is demonstrated that direct influence of the plasma, where charged particles contact bacteria directly, produces inactivation much faster than the indirect treatment, where plasma afterglow is delivered to the bacteria with a gas flow through the plasma region. This leads to an important conclusion that the effect of charged particles on plasma plays the essential role in interaction with living organisms, although synergy with longer living active molecules and atoms as well as UV radiation generated in plasma and at the surface of tissues may also play a role in inactivation. Show less

Initiation of apoptosis, or programmed cell death, is an important issue in cancer treatment as cancer cells frequently have acquired the ability to block apoptosis and thus are more resistant to chemotherapeutic drugs. Targeted and perhaps selective destruction of cancerous tissue is desirable for many reasons, ranging from the enhancement of or aid to current medical methods to problems currently lacking a solution, i.e., lung cancer. Demonstrated in this publication is the inactivation… Show more

Initiation of apoptosis, or programmed cell death, is an important issue in cancer treatment as cancer cells frequently have acquired the ability to block apoptosis and thus are more resistant to chemotherapeutic drugs. Targeted and perhaps selective destruction of cancerous tissue is desirable for many reasons, ranging from the enhancement of or aid to current medical methods to problems currently lacking a solution, i.e., lung cancer. Demonstrated in this publication is the inactivation (killing) of human Melanoma skin cancer cell lines, in vitro, by Floating Electrode Dielectric Barrier Discharge (FE-DBD) plasma. Not only are these cells shown to be killed immediately by high doses of plasma treatment, but low doses are shown to promote apoptotic behavior as detected by TUNEL staining and subsequent flow cytometry. It is shown that plasma acts on the cells directly and not by ‘‘poisoning’’ the solution surrounding the cells, even through a layer of such solution. Potential mechanisms of interaction of plasma with cells are discussed and further steps are proposed to develop an understanding of such systems. Show less

Mechanisms of blood coagulation by direct contact of nonthermal atmospheric pressure dielectric barrier discharge (DBD) plasma are investigated. This paper shows that no significant changes occur in the pH or Ca2+ concentration of blood during discharge treatment. Thermal effects and electric field effects are also shown to be negligible. Investigating the hypothesis that the discharge treatment acts directly on blood protein factors involved in coagulation, we demonstrate aggregation of… Show more

Mechanisms of blood coagulation by direct contact of nonthermal atmospheric pressure dielectric barrier discharge (DBD) plasma are investigated. This paper shows that no significant changes occur in the pH or Ca2+ concentration of blood during discharge treatment. Thermal effects and electric field effects are also shown to be negligible. Investigating the hypothesis that the discharge treatment acts directly on blood protein factors involved in coagulation, we demonstrate aggregation of fibrinogen, an important coagulation factor, with no effect on albumin. We conclude that direct DBD treatment triggers selective natural mechanisms of blood coagulation. Show less

Thermal plasma discharges have been widely used in the past for treatment of living human and animal tissue. However, extensive thermal damage and tissue desiccation occurs due to extreme temperatures. Some solutions have been offeredwhere the temperature is lowered by short current pulses, addition of noble gases, or significant decrease in the size of treatment electrodes.We propose a method of direct treatment of living tissue that occurs at room temperature and pressure without visible or… Show more

Thermal plasma discharges have been widely used in the past for treatment of living human and animal tissue. However, extensive thermal damage and tissue desiccation occurs due to extreme temperatures. Some solutions have been offeredwhere the temperature is lowered by short current pulses, addition of noble gases, or significant decrease in the size of treatment electrodes.We propose a method of direct treatment of living tissue that occurs at room temperature and pressure without visible or microscopic tissue damage. The presented Floating-Electrode Dielectric Barrier Discharge plasma is proven electrically safe to human subjects and our results show no gross (visual) or histological (microscopic) damage to skin samples in minutes, complete tissue sterilization from skin flora in seconds, and blood clot formation in seconds of electric plasma treatment. We also observe significant hastening of blood clot formation via electric plasma induced catalysis of “natural” processes occurring in human blood. A model describing these processes is offered. Show less

Method of biochemical patterning which allows for micro- and nano-scale resolution on nonplanar substrates is presented. Utilizing this method, bio-molecules (including DNA, proteins, and enzymes) can be delivered to charged locations on surfaces by charged water buffer droplets. Charging of water droplets is accomplished using dielectric barrier discharge (DBD) plasma. DBD was effectively stabilized in the presence of high concentration of micron-size water droplets. The concepts of the… Show more

Method of biochemical patterning which allows for micro- and nano-scale resolution on nonplanar substrates is presented. Utilizing this method, bio-molecules (including DNA, proteins, and enzymes) can be delivered to charged locations on surfaces by charged water buffer droplets. Charging of water droplets is accomplished using dielectric barrier discharge (DBD) plasma. DBD was effectively stabilized in the presence of high concentration of micron-size water droplets. The concepts of the proposed method, as well as first experimental results supporting the idea are discussed in this paper. Show less

A new method for locally targeted drug delivery is proposed that employs magnetic implants placed directly in the cardiovascular system to attract injected magnetic carriers. Theoretical simulations and experimental results support the assumption that using magnetic implants in combination with externally applied magnetic field will optimize the delivery of magnetic drug to selected sites within a subject.

A novel self-aligned ‘soft masking’ method that is compatible with traditional photolithographic processes is demonstrated. This method uses a suspension of ultrafine iron oxide grains (ferrofluid) to protect or de-protect selected areas of a magnetically patterned substrate according to a programmable sequence. Automatic mask formation and registration is controlled by ferromagnetic alignment marks patterned on a substrate. External magnetic field bias applied to the system causes ferrofluid… Show more

A novel self-aligned ‘soft masking’ method that is compatible with traditional photolithographic processes is demonstrated. This method uses a suspension of ultrafine iron oxide grains (ferrofluid) to protect or de-protect selected areas of a magnetically patterned substrate according to a programmable sequence. Automatic mask formation and registration is controlled by ferromagnetic alignment marks patterned on a substrate. External magnetic field bias applied to the system causes ferrofluid to aggregate only over designated areas on the surface, thereby masking those areas from UV or chemical exposure. Show less