It is estimated that 15 percent of individuals with diabetes mellitus suffer from diabetic ulcers worldwide. The aim of this study is to present a non-thermal atmospheric plasma treatment as a novel therapy for diabetic wounds. The plasma consists of ionized helium gas that is produced by a high-voltage (8 kV) and high-frequency (6 kHz) power supply. Diabetes was induced in rats via an intravascular injection of streptozotocin. The plasma was then introduced to artificial xerograph wounds in the rats for 10 minutes. Immunohistochemistry assays was performed to determine the level of transforming growth factor (TGF-β1) cytokine. The results showed a low healing rate in the diabetic wounds compared with the wound-healing rate in non-diabetic animals (P < 0.05). Moreover, the results noted that plasma enhanced the wound-healing rate in the non-diabetic rats (P < 0.05), and significant wound contraction occurred after the plasma treatment compared with untreated diabetic wounds (P < 0.05). Histological analyses revealed the formation of an epidermis layer, neovascularization and cell proliferation. The plasma treatment also resulted in the release of TGF-β1 cytokine from cells in the tissue medium. The findings of this study demonstrate the effect of plasma treatment for wound healing in diabetic rats.

Cold atmospheric plasma (CAP) was shown to decrease bacterial load in chronic wounds. It was also presented as a novel approach to healing wounds in both in vitro and in vivo experiments. We aimed to examine the first randomized clinical trial for the use of CAP in diabetic foot ulcers. Patients (n = 44) were randomly double-blinded, and assigned to receive standard care (SC, n = 22) without or with CAP, to be applied three times a week for three consecutive weeks (SC + CAP, n = 22), using block randomization with mixing block sizes of four. The trial was conducted at the Diabetes Research Center in Tehran, Iran. CAP was generated from ionized helium gas in ambient air, and driven by a high voltage (10 kV) and high frequency (6 kHz) power supply. Primary outcomes were wound size, number of cases reaching wound size of <0.5, and a bacterial load after over three weeks of treatment. CAP treatment effectively reduced the fraction of wound size (p = 0.02). After three weeks, the wounds to reach fraction wound size of ≤0.5 was significantly greater in the SC + CAP group (77.3%) compared to the SC group (36.4%) (p = 0.006). The mean fraction of bacterial load counted in each session 'after CAP exposure' was significantly less than 'before exposure' measures. CAP can be an efficient method to accelerate wound healing in diabetic foot ulcers, with immediate antiseptic effects that do not seem to last long. Diabetes mellitus (diabetes) accounts for 3.9% of annual non-communicable disease-related deaths that occurred worldwide and also caused significant morbidity, impairing the patients' quality-of-life 1. Diabetic foot syndrome (DFS) is directly associated with diabetes, contributing to significant morbidity, as well as economic and social burden 2. It is estimated that approximately 25% of diabetic patients will develop DFS in their lives 3. Some authors reported that patients have a 3 to 11% annual risk of developing lower-extremity ulcers 2. Despite optimal treatment, diabetic ulcers are refractory to wound healing, with more than 50% recurring in the wounds after three years 4. Diabetic foot infection can also lead to complications, e.g., delayed healing process, systemic infections, and amputation. In addition, over 15% of patients with DFS experiences a lower limb amputation 5. The survival rate is found to be significantly lower in patients who require a lower limb amputation. The cost for two years of care with a newly-diagnosed foot ulcer is over $2,700 5. This has prompted more research and studies to identify viable alternatives or additive treatment options. Cold atmospheric plasma (CAP) is an innovative approach in wound healing. In vitro 6 and initial clinical studies for chronic wounds in animals 7,8 and humans 9-12 have shown that CAP decreases their bacterial load and promotes healing without any significant side effects on normal tissue. Additionally, CAP was found to facilitate the transformation of the chronic wound from becoming a stagnating wound or an acute healing wound through modulation of the i...

This study aimed to evaluate the effects of micron sized non-thermal atmospheric pressure plasma inside the animal body on breast cancer tumor. The μ-plasma jet consists of micron sized hollow tube in which pure helium gas is ionized by high voltage (4 kV) and high frequency (6 kHz). The efficiency of the plasma treatment in killing cancer cells was first investigated by cell viability measurements of treated 4T1 cells using flow cytometry and cell cycle analysis. For exploration of the in vivo effects of the plasma treatment, the BALB/c mice inoculated by 4T1 cell lines were exposed subcutaneously to plasma for 3 minutes. In addition, H&E staining, TUNEL and Western blotting assays were performed in order to observed the effects of the non-thermal plasma on the tumor cells. The results showed that the efficiency of the plasma in suppression of the tumor growth is comparable to that of a typical chemotherapy drug. Moreover, the results indicated that the plasma induces apoptosis in the tumor tissue and increases the ratio of the apoptotic to anti-apoptotic protein expression. We believe that these findings presented herein may extend our knowledge of the mechanisms by which the plasma exerts its promising anti-cancer effects.

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Knowing which processes and species are responsible for discharge inception is important for being able to speed up, delay, or completely avoid it. We study discharge inception in 500 mbar synthetic air by applying 10 ms long 17 kV pulses with a repetition frequency of 2 Hz to a pin-to-plate electrode geometry with a gap length of 6 cm. We record inception times for hundreds of pulses by measuring the time delay between the rising edge of the high-voltage (HV) pulse and the signal from a photo-multiplier tube. Three characteristic time scales for inception are observed: (1) 20 ns, (2) 25 μs, and (3) 125 μs. To investigate the underlying processes, we apply a low-voltage (LV) pulse in between the HV pulses. These LV pulses can speed up or delay discharge inception, and our results suggest that the three time scales correspond to: (1) free electrons or electron detachment from negative ions close to the electrode, (2) a process that liberates electrons from (quasi)-neutrals, and (3) the drift of an elevated density of negative ions to the ionization zone. However, each of these explanations has its caveats, which we discuss. We present a theoretical analysis of the distribution of inception times, and perform particle simulations in the experimental discharge geometry. Some of the observed phenomena can be explained by these approaches, but a surprizing number of open questions remain.

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Positive streamers can be affected significantly by preceding discharges such as earlier streamers or a corona discharge. In this paper, we primarily discuss the effect of such a corona discharge on subsequent positive streamers with different intervals between them (0/500/990 ms) in air and pure nitrogen at 80 mbar with a repetition frequency of 1 Hz. We found that in air, when the interval time is 500 or 990 ms, a preceding discharge leads to shorter and weaker streamers or even prevents streamer inception altogether. This is likely due to negative ions which have converted to species that are harder to detach. The weaker streamers are also caused by more stable inception clouds which branch out later. When a corona discharge immediately precedes a streamer discharge in air, the streamers become longer, brighter while some branches develop from the side of the electrode instead of its tip. These effects are likely all related to plasma shielding caused by the corona discharge. In nitrogen, inception is primarily caused by electrons instead of negative ions. When the interval time is 500 or 990 ms in this gas, there is nearly no difference between streamers with and without a preceding corona discharge, because the inception time in nitrogen is the formative time that is not sensitive to the initial electron density. For near-zero intervals between corona and streamer discharges in nitrogen, streamers become smoother and thicker which can be attributed to a higher background ionization left by the corona discharge.

Lightning is observed to incept in thundercloud electric fields below the threshold value Ek for discharge initiation. To explain this, the local enhancement of the electric field by hydrometeors is considered. The conditions for the onset of positive corona discharges are studied in air for ellipsoidal geometries. A hydrometeor is simulated as an individual charged conductor in zero ambient field; there is only a field generated by the charge on the hydrometeor surface. By doing so, the feasibility of corona inception from ellipsoidal hydrometeors can be formulated based on the self‐sustaining condition of electron avalanches. For hydrometeor dimensions of a few millimeters and typical thundercloud pressure, values above 2.4 Ek are found for the onset electric field at the tip of the ellipsoid. From simulations the required ambient electric field for corona onset from an uncharged hydrometeor can then be derived. This results in values between 0.07 Ek and 0.8 Ek for semiaxes aspect ratios between 0.01 and 1. The charge required on the hydrometeor surface for corona onset for typical pressures is minimum for semiaxes aspect ratios increasing from 0.12 to 0.22 for decreasing hydrometeor volume from 42 to 4.2 mm3. For representative simulated hydrometeors, onset charges are between 495 and 2,430 pC. For a hydrometeor volume of 4.2 mm3 results are comparable to measured precipitation charges for aspect ratios between 0.16 and 0.32. From the results it is concluded that corona onset from ellipsoidal hydrometeors of a realistic volume can be achieved in thundercloud conditions for certain aspect ratios.