Sameer Kalghatgi

Effects of Non-Thermal Plasma on Mammalian Cells

Thermal plasmas and lasers have been widely used in medicine to cut, ablate and cauterize tissues through heating; in contrast, non-thermal plasma produces no heat, so its effects can be selective. In order to exploit the potential for clinical applications, including wound healing, sterilization, blood coagulation, and cancer treatment, a mechanistic understanding of the interaction of non-thermal plasma with living tissues is required. Using mammalian cells in culture, it is shown here that non-thermal plasma created by dielectric barrier discharge (DBD) has dose-dependent effects that range from increasing cell proliferation to inducing apoptosis. It is also shown that these effects are primarily due to formation of intracellular reactive oxygen species (ROS). We have utilized γ-H2AX to detect DNA damage induced by non-thermal plasma and found that it is initiated by production of active neutral species that most likely induce formation of organic peroxides in cell medium. Phosphorylation of H2AX following non-thermal plasma treatment is ATR dependent and ATM independent, suggesting that plasma treatment may lead to replication arrest or formation of single-stranded DNA breaks; however, plasma does not lead to formation of bulky adducts/thymine dimers.

Mechanism of Blood Coagulation by Nonthermal Atmospheric Pressure Dielectric Barrier Discharge Plasma

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.

Non-thermal dielectric barrier discharge plasma treatment of endothelial cells

Non-thermal dielectric barrier discharge plasma is now being widely developed for various medical applications such as skin sterilization, blood coagulation, induction of apoptosis in malignant tissues, and wound healing among others. In this paper, we investigate the toxicity of non-thermal plasma treatment on endothelial cells, which line all blood contacting surfaces in the body. Our initial results indicate that low power non-thermal plasma is relatively non-toxic to endothelial cells at short exposure times up to 30 s, while non-thermal plasma treatment at longer exposure times is cytotoxic. Non-thermal plasma at shorter exposure times may induce proliferation in the cells.

Manipulation of nonmagnetic nanobeads in dilute ferrofluid

Patterns of submicron Co islands in conjunction with a uniform, static, or rotating magnetic field are used to demonstrate the possibility of assembling 100–300nm nonmagnetic latex beads in designated locations and manipulating their movements on surfaces.

Applications of Non Thermal Atmospheric Pressure Plasma in Medicine

Non-thermal atmospheric pressure plasma is now being developed for use in various medical applications. Over the past few years a lot of clinical applications of non-thermal plasma have been tested and the results show promising potential for Plasma Medicine. In this paper we present a review of various applications of non-thermal plasma in medicine like non-thermal plasma assisted blood coagulation and skin sterilization, melanoma skin cancer treatment and treatment of cornea lesions.

Cell proliferation following non-thermal plasma is related to reactive oxygen species induced fibroblast growth factor-2 release

Non-thermal dielectric barrier discharge plasma is currently being developed for a wide range of medical applications, including blood coagulation, malignant cell apoptosis, and wound healing. However, the effect of non-thermal plasma on the vasculature is unclear. Blood vessels are affected during plasma treatment of many tissues, and vessels themselves may be an important clinical plasma therapy target. We investigated the effect of non-thermal plasma treatment on endothelial cells, which line the inner surface of blood vessels. Non-thermal plasma treatment at short exposures (up to 30 seconds; 4 J/cm2) was relatively non-toxic to endothelial cells. Endothelial cells treated with plasma for 30 seconds demonstrated twice as much proliferation as untreated cells five days after plasma treatment. Proliferation was abrogated by a fibroblast growth factor-2 neutralizing antibody and reactive oxygen species inhibitors. This suggests that plasma-induced endothelial cell proliferation is caused by growth factor release following reactive oxygen species cell membrane damage. These data suggest that low power non-thermal plasma treatment is a potential novel therapy for promotion of endothelial cell mediated angiogenesis.

Physical and biological mechanisms of plasma interaction with living tissue

Non-thermal plasmas are already well-known for their sterilization ability; however the mechanisms of this sterilization are under debate. Short and long living active species and radicals produced by plasma, ultraviolet (UV) radiation, local thermal effects, and bombardment by charges particles are all listed as potential candidates for sterilization of various surfaces. In this work, biochemical and physical mechanisms of plasma interaction with biological materials will be discussed. Direct interaction where a surface of a microorganism is used as one of the plasma-generating electrodes is compared with indirect interaction where plasma is generated elsewhere and the plasma-treated gas is carried off to a remote location for microorganism treatment. Under these conditions, the authors show that: a) direct treatment by plasma is orders of magnitude faster than indirect treatment; and b) interaction of a microorganism with charged particles is the primary inactivation mechanism. Microorganisms selected for this study were Streptococcus, Staphylococcus, Yeast, and E. coli. Samples were treated by dielectric barrier discharge system in either continuous- wave (sinusoidal, 4-20 kHz), microsecond pulse (100 mus pulse duration, 0.1-1 kHz repetition rate), or nanosecond pulse modes (3 kV/ns rise time, 10-40 ns pulse duration, 0.1- 1 kHz repetition rate). Microorganisms were either treated directly by plasma or plasma afterglow was utilized.

Non-thermal plasma enhances endothelial cell proliferation through fibroblast growth factor-2 release

Non-thermal atmospheric pressure dielectric barrier discharge plasma is currently being developed for a wide variety of clinical applications, including skin sterilization, blood coagulation, malignant cell apoptosis, and wound healing [1]. Angiogenesis, the growth of new blood vessels from existing vessels, is critical in wound healing. Endothelial cells, which line the inner surface of blood vessels, control the angiogenic process through production, release, and response to growth factors. We hypothesized that low level plasma treatment can enhance endothelial cell proliferation through growth factor release.

On the interaction of non-thermal atmospheric pressure plasma with tissues

Non-thermal atmospheric pressure plasma is now being widely developed for various clinical applications such as skin sterilization, blood coagulation, cancer treatment, angiogenesis and wound healing among others. However, understanding of mechanism of interaction between non-thermal plasma and mammalian cells is lacking. Here we investigated the possibility that the dose of non-thermal plasma can be tuned to achieve various results depending on the clinical applications ranging from enhanced cell proliferation to inducing apoptosis in malignant tissue. We also present some of the underlying mechanisms of interaction of non-thermal plasma with mammalian cells.

Toxicity analysis of direct nonthermal plasma treatment of living tissue

Non-thermal dielectric barrier discharge plasma produced at normal atmospheric pressure and applied directly to living tissues is now being widely considered for various applications in medicine, viz; skin sterilization, wound treatment, treatment in malignant tissues and many others. One of the key questions that arise in this type of topical treatment is whether the skin remains undamaged after non-thermal plasma treatment. In this paper we study the possible short term and long term toxic effects of the non-thermal plasma treatment on intact living tissue. The results from the previous rodent model provided strong evidence for the ability of non-thermal plasma to sterilize the surface of the tissue without any visible or microscopic damage to the tissue. We evaluated the potential toxic effects of non-thermal plasma treatment on underlying skin cells and tissue on intact porcine skin, since it is well established that porcine (pig) skin closely resembles human skin. Based on prior knowledge that non-thermal plasma has non-damaging and damaging regimes, an experimental protocol based on the pig model was constructed. In a Yorkshire pig model, the intact skin treatment was carried out at varying doses to locate the damaging power/time (dose) combination and the resulting skin damage was analyzed. Once the dose where damage occurred was located, the treatment was stopped recording the power level and time of application. Then successively lower power levels were applied on different patches to find a dose (power/time) which was non-damaging for prolonged treatment times. The pig was kept alive for one day post treatment and the tissue samples were sectioned before euthanizing the animal. From the experiments we determined that a dose of 15 mins at a low power of 0.2 Watt/cm2 caused no visible or microscopic damage to the tissue while a dose of 3 mins at high power of 1.0 Watt/cm2 caused a second degree burn. These results were confirmed by histology staining. Of note is that sterilization is achieved in about 5 sec at a low power treatment of 0.2 Watt/cm2. Detailed analysis of any biochemical changes and inflammatory response initiation in the treated tissue will be carried out. In this paper we show that low power plasma treatment is non-toxic to intact pig skin.