G. Friedman

Application of nanosecond-pulsed dielectric barrier discharge for biomedical treatment of topographically non-uniform surfaces

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. (Some figures in this article are in colour only in the electronic version)

Direct and controllable nitric oxide delivery into biological media and living cells by a pin-to-hole spark discharge (PHD) plasma

Nitric oxide has great potential for improving wound healing through both inflammatory and vascularization processes. Nitric oxide can be produced in high concentrations by atmospheric pressure thermal plasmas. We measured the physical characteristics and nitric oxide production of a pin-to-hole spark discharge (PHD) plasma, as well as plasma-produced nitric oxide delivery into liquid and endothelial cells. The plasma temperature was calculated as 9030 ± 320 K by the Boltzmann method, which was adequate to produce nitric oxide, although the average gas temperature was near room temperature. The plasma produced significant UV radiation and hydrogen peroxide, but these were prevented from reaching the cells by adding a straight or curved tube extension to the plasma device. Plasma-produced nitric oxide in gas reached 2000 ppm and rapidly diffused into liquid and cells. Cells remained viable following plasma treatment and showed a linear increase in cGMP concentration with plasma treatment, indicating an intracellular functional response to PHD plasma NO. These data suggest that this plasma may provide a novel method for delivering NO locally and directly for enhanced wound healing.

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.

Non-thermal plasma applications in air sterilization

Summary form only given. In our present study, we are constructing a physiochemical model of the oxidizing effects of the active chemical species generated by non-thermal atmospheric pressure plasma on the influenza A virus. The results of our model provides us with an estimate of the optimal dose of active species required to destroy varying concentrations of airborne influenza viruses. We are specifically investigating the sterilizing effects of hydroxyl radicals (OH) because they are the most aggressive of the active chemical species created by non-thermal plasma and have a much shorter lifetime than ozone (O/sub 3/). Ozone is a proven sterilizing agent, but it is known to have negative health effects and its longer lifetime can potentially lead to human exposure in shorter ventilation systems. Additionally, in order to achieve complete air sterilization, that is the complete oxidation of all organic matter including DNA, we experiment with plasmas that have a relatively high temperature and large power density that can work at atmospheric pressure, but are still as efficient as cold plasma in providing active species. An example of such transitional non-thermal plasma is Gliding Arc in Tornado (GAT), which uses a reverse vortex flow to provide high velocity to a gliding arc discharge resulting in rapid convective cooling of the arc, recirculation of active species, and longer residence time of the organic matter in the plasma discharge zone.

Interaction effects enhancing magnetic particle detection based on magneto-relaxometry

We investigated the effects of dipolar interactions on the long-time magnetization decay M(t) in clusters of magnetic nanoparticles. Applying the Neel-Arrhenius thermal activation picture shows that M(t) generally follows stretched exponential behavior, dependent not only on the dipolar interaction strength, geometry of particle arrangement within clusters, but also on the field history applied during the initialization. As demonstrated, combining these factors could serve to enhance the degree of resolution in magnetic particle detection based on magneto-relaxometry.

Uniform and Filamentary Nature of Continuous-Wave and Pulsed Dielectric Barrier Discharge Plasma

Observations of atmospheric pressure DBD plasma were conducted through the transparent electrode in Air, Argon, Helium, Nitrogen and Oxygen gasses at 1 and 3 standard liters per minute (s1pm) flow rates through the discharge gap, utilizing three types of excitation waveforms. Three phenomena were observed: (1) plasma filaments travel with the gas at the same speed as the gas for some but not all gases; (2) propagation of excitation is observed in Nitrogen plasma and the filament motion has no directional preference with gas flow direction; and (3) Oxygen, Nitrogen and Helium plasmas were observed to be rather uniform at least over longer time periods.

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.

Self-consistent model of field gradient driven particle aggregation in magnetic fluids

Particle aggregation in magnetic colloids driven by strong magnetic field gradients is studied using self-consistent field calculations. The model takes into account field screening due to average fluid magnetization and demagnetizing field arising from spatially varying magnetic particle concentration. Solutions for the problem of particle aggregation due to a single magnetic pole demonstrate that, in high particle concentration, the magnetic field must be calculated self-consistently.

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 of direct non-thermal atmospheric pressure plasma treatment of living tissue

Non-thermal atmospheric pressure dielectric barrier discharge plasma applied directly to living tissues is now being widely considered for various clinical applications. One of the key questions that arise in this type of topical treatment is if the skin remains undamaged after non-thermal plasma treatment.