Hamid Razavi

Evaluation of the effects of a plasma activated medium on cancer cells

The interaction of low temperature plasma with liquids is a relevant topic of study to the field of plasma medicine. This is because cells and tissues are normally surrounded or covered by biological fluids. Therefore, the chemistry induced by the plasma in the aqueous state becomes crucial and usually dictates the biological outcomes. This process became even more important after the discovery that plasma activated media can be useful in killing various cancer cell lines. Here, we report on the measurements of concentrations of hydrogen peroxide, a species known to have strong biological effects, produced by application of plasma to a minimum essential culture medium. The activated medium is then used to treat SCaBER cancer cells. Results indicate that the plasma activated medium can kill the cancer cells in a dose dependent manner, retain its killing effect for several hours, and is as effective as apoptosis inducing drugs.

Indirect Generation of a Large-Volume Diffuse Plasma by an Ionization Wave From a Plasma Jet

Low temperature plasma jets are the product of fast ionization waves that are guided within a gas channel. Here, we present a novel way to use an ionization wave from an external plasma jet to remotely produce a large-volume diffuse low pressure plasma inside an electrodeless Pyrex chamber.

Effects of growth medium treated by plasma pencil on the viability of scaber cancer cells

Low temperature plasma (LTP) generates biologically tolerable gas discharges, suitable for the treatment of biological tissues1. In recent years extensive research has been done on the biomedical applications of LTP including bacteria inactivation and cancer cell treatment.

Effects of aged PAM on cancer cells

The study of the effects of low temperature plasma (LTP) on cancer cells, in vitro and in vivo, is today one of the most active research areas of plasma medicine. Here, we study the interaction of LTP with cancer cells which were grown overnight and then seeded into MEM (minimal essential medium) growth culture treated by the plasma pencil at different exposure times. Plasma activated media (PAM) proved to be very effective in killing cancer cells. In our study we used “aged” PAM for different lengths of time to determine how long the treated media can be stored and still maintain its potency against cancerous cells. We found that fresh PAM (not aged) is most potent, but PAM produced by 4 minutes exposure to LTP and aged for up to 8 hours was still able to induce cell killing. Cell viability was determined immediately after treatment and at various times (hours/days) post plasma exposure, by Trypan Blue exclusion assay. The pH of the medium was monitored by a pH meter at various exposure times. Our measurements showed that buffered PAM maintained a stable pH value and therefore acidification of the media was not an issue. We hypothesize that it was the long lived solvated oxygen reactive species and nitrogen reactive species and their reaction by-products in the media that are responsible for the observed effects.

Using fluorescence to measure hydrogen peroxide concentrations in plasma activated media

Recently several investigators have shown that plasma activated media (PAM) is as effective in killing cancer cells as direct plasma treatment of the cells [1], [2]. Low temperature plasma (LTP) generated in oxygen or air containing environments produces various chemically reactive species such as OH and O. These species have very short lifetimes and do not penetrate deep in liquid media. However, they can interact with the liquid to generate relatively stable long lived species inside the volume of the liquid. One such reactive species is hydrogen peroxide (H2O2). Hydrogen peroxide is known to cause various oxidizing reactions in biological cells, including the peroxidation of lipids and DNA damage. Knowing how much H2O2 is generated when liquid biological media is exposed to LTP is therefore of great interest.

Spatial correlation between emitting species and plasma bullet propagation in low temperature plasma jets

Summary form only given. Low temperature plasma jets are being extensively used in plasma processing including biomedical applications1. This is due to their ability of launching controllable plasma plumes in atmospheric pressure air, not confined by electrodes. These plasma jets are in fact vehicles transporting reactive chemical species to a remote substrate in the form of the so-called “Plasma Bullets”2. Plasma bullets are ionization waves able to travel at very high speeds. Therefore, since plasma jets are in fact series of propagating plasma packets/bullets, the spatial distribution of the chemical species is a dynamic quantity that varies with the spatial location of the plasma bullet. This is due to substantial changes in size and content that the plasma bullet undergoes as it mixes with the surrounding air along its propagation path.In this paper, the spatial distributions of the emitting species emanating from the plasma plume of our plasma pencil are measured by Optical Emission Spectroscopy and correlated with the position and physical characteristics of the plasma bullet. In this experiment new detailed data of the relative density of species such as N2+, OH, N2, He and atomic oxygen within a traveling bullet through the air are measured by ICCD camera connected to an imaging spectrometer. Spatially resolved emitted light intensity of each bullet is also measured in order to quantify the results.