Soheila Mohades

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.

Killing adherent and nonadherent cancer cells with the plasma pencil

The application of low temperature plasmas in biology and medicine may lead to a paradigm shift in the way various diseases can be treated without serious side effects. Low temperature plasmas generated in gas mixtures that contain oxygen or air produce several chemically reactive species that have important biological implications when they interact with eukaryotic or prokaryotic cells. Here, a review of the effects of low temperature plasma generated by the plasma pencil on different cancerous cells is presented. Results indicate that plasma consistently shows a delayed killing effect that is dose dependent. In addition, there is some evidence that apoptosis is one of the pathways that leads to the death of the cells, indicating that plasma initiates cell signaling pathways.

Measurements of Plasma-Generated Hydroxyl and Hydrogen Peroxide Concentrations for Plasma Medicine Applications

Low-temperature, atmospheric pressure plasmas (LTPs) produce reactive oxygen and nitrogen species [O, O^-₂, O₂ (¹Δ), hydroxyl (OH), H₂O₂, NO, NO₂ . . .]. In biological and medical applications, the concentrations and fluxes of these species play a crucial role in the biological outcomes. Many of these species are produced in the gaseous phase and at the gas-liquid interface when LTP is applied to biological media. In the medium, the plasma-produced oxygen reactive species and nitrogen reactive species generate long-lived species, such as hydrogen peroxide (H₂O₂), nitrites (NO^-₂), nitrates (NO^-₃), and organic peroxides (RO₂). In particular, hydrogen peroxide is known to cause various oxidizing reactions in biological cells. One of the pathways to the creation of hydrogen peroxide is the reaction between OH radicals. Therefore, the measurement of OH concentration is of great importance. In this paper, we report on the measurements of OH in the gas-liquid interface using laser-induced fluorescence and measurements of H₂O₂ concentration in biological media. In addition, the effects of plasma activated media on cancer cells are briefly discussed.

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.

Images of SCaBER Cells Treated by a Low Temperature Plasma Jet

Squamous cell carcinoma of the bladder is a rare type of bladder cancer that forms as a result of chronic irritation of the epithelial lining of the bladder. The cell line used in this paper is SCaBER (ATCC HTB3) derived from squamous cell carcinoma of the human urinary bladder. Current treatments of bladder cancer include surgery, radiation, and chemotherapy. However, the cost of these treatments, potential toxicity of the chemotherapeutic agents, and systemic side-effects warrant an alternative to current cancer treatment. In this paper, we present images of SCaBER cells treated by the plasma pencil, a device that generates a low temperature plasma plume at atmospheric pressure. The images show that after plasma treatment of only a few minutes substantial killing of SCaBER cells occur and that the cells die in a delayed manner, postplasma 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.