Alexey Shashurin

Cold plasma selectivity and the possibility of a paradigm shift in cancer therapy

Background:Plasma is an ionised gas that is typically generated in high-temperature laboratory conditions. However, recent progress in atmospheric plasmas has led to the creation of cold plasmas with ion temperature close to room temperature.Methods:Both in-vitro and in-vivo studies revealed that cold plasmas selectively kill cancer cells.Results:We show that: (a) cold plasma application selectively eradicates cancer cells in vitro without damaging normal cells; and (b) significantly reduces tumour size in vivo. It is shown that reactive oxygen species metabolism and oxidative stress responsive genes are deregulated.Conclusion:The development of cold plasma tumour ablation has the potential of shifting the current paradigm of cancer treatment and enabling the transformation of cancer treatment technologies by utilisation of another state of matter.

Living tissue under treatment of cold plasma atmospheric jet

The interaction of the cold atmospheric plasma jet with fibroblast cells was studied. Plasma jet was initiated in the helium flow blowing through the syringe by application of high ac voltage to the discharge electrodes. The plasma jet had a length of 5cm and a diameter of 1.5–2mm in ambient air. Treatment of cells with plasma jet resulted in decreasing of cell migration rate, cell detachment, and appearance of “frozen” cells, while treatment with helium flow (no plasma) resulted in appearance of frozen cells only. A variety of cellular responses was explained by different intensities of treatment.

Single-step synthesis and magnetic separation of graphene and carbon nanotubes in arc discharge plasmas

The unique properties of graphene and carbon nanotubes made them the most promising nanomaterials attracting enormous attention, due to the prospects for applications in various nanodevices, from nanoelectronics to sensors and energy conversion devices. Here we report on a novel deterministic, single-step approach to simultaneous production and magnetic separation of graphene flakes and carbon nanotubes in an arc discharge by splitting the high-temperature growth and low-temperature separation zones using a non-uniform magnetic field and tailor-designed catalyst alloy, and depositing nanotubes and graphene in different areas. Our results are very relevant to the development of commercially-viable, single-step production of bulk amounts of high-quality graphene.

Temporal behavior of cold atmospheric plasma jet

Temporally resolved evolution of parameters in atmospheric plasma jet is studied by means of microwave scattering, fast photographing, and measuring of jet currents. It is observed that streamer (“plasma bullet”) propagating along with gas flow is generated immediately after the breakdown. It is demonstrated that an afterglow plasma column remains on the way of streamer passing. Lifetime of the afterglow plasma column is 3–5 μs, which is longer than that of the streamer.

Cold atmospheric plasma for the ablative treatment of neuroblastoma

BACKGROUND Recent breakthroughs have allowed for production of plasma at room temperature. Cold atmospheric plasma (CAP) may offer the capability of delivering reactive oxygen species directly into tissues, representing a novel modality for targeted cancer therapy. We studied helium-based CAPs effect on neuroblastoma, both in-vitro and in an in-vivo murine model. METHODS Mouse neuroblastoma cultures were treated with CAP for 0, 30, 60, and 120 s and assayed for apoptotic and metabolic activity immediately and at 24 and 48 h post-treatment. Five-millimeter tumors were ablated with a single transdermal CAP treatment, and tumor volume and mouse survival were measured. RESULTS CAP decreased metabolic activity, induced apoptosis, and reduced viability of cancer cells in proportion to both duration of exposure and time post-treatment. In-vivo, a single treatment ablated tumors and eventual tumor growth was decelerated. Furthermore, survival nearly doubled, with median survival of 15 vs. 28 days (p<0.001). CONCLUSIONS Our findings demonstrate the sensitivity of neuroblastoma to CAP treatment, both in-vitro and in an in-vivo mouse model of established tumor. While further investigation is necessary to establish the mechanism and optimize the treatment protocol, these initial observations establish cold atmospheric plasma as a potentially useful ablative therapy in neuroblastoma.

Arc plasma synthesis of carbon nanostructures: where is the frontier?

In this perspective paper, we critically analyse the state-of-the-art of arc discharge technique of carbon nanoparticle synthesis. We discuss improving controllability of the arc discharge synthesis of carbon nanotubes, synthesis of graphene as well as general understanding of the synthesis process. Fundamental issues related to relationship between plasma parameters and carbon nanostructure characteristics are considered. Effects of electrical and magnetic fields applied during single-wall carbon nanotube synthesis in arc plasma are explored. Finally our personal opinion on what future trends will be in arc discharge synthesis is offered.

Temporary-resolved measurement of electron density in small atmospheric plasmas

A new method for temporally resolved measurements of absolute values of plasma density applicable for wide spectrum of small-size atmospheric plasmas and utilizing Rayleigh microwave scattering on the tested plasma object is proposed. The absolute electron density measurements in an atmospheric plasma jet revealed presence of two consecutive breakdowns during the half-wave of the discharge-driven high voltage. The ionization mechanisms of both breakdowns are considered.

Tailored Distribution of Single-Wall Carbon Nanotubes from Arc Plasma Synthesis Using Magnetic Fields

We report a method for tuning the distribution of single-wall carbon nanotubes (SWCNTs) produced by the anodic arc production method via the application of nonuniform magnetic fields to the gap region during synthesis. Raman, ultraviolet-visible-near-infrared absorbance and near-infrared fluorescence spectroscopies were used to characterize samples together with scanning electron microscopy. Application of the nonuniform magnetic field 0.2-2 kG results in a broadening of the diameter range of SWCNTs produced toward decreased diameters, with substantial fractions of produced SWCNTs being of small diameter, less than ∼1.3 nm, at the highest field. The ability to tune production of the arc production method may allow for improvement in achievable SWCNT properties.

Electric propulsion for small satellites

Propulsion is required for satellite motion in outer space. The displacement of a satellite in space, orbit transfer and its attitude control are the task of space propulsion, which is carried out by rocket engines. Electric propulsion uses electric energy to energize or accelerate the propellant. The electric propulsion, which uses electrical energy to accelerate propellant in the form of plasma, is known as plasma propulsion. Plasma propulsion utilizes the electric energy to first, ionize the propellant and then, deliver energy to the resulting plasma leading to plasma acceleration. Many types of plasma thrusters have been developed over last 50 years. The variety of these devices can be divided into three main categories dependent on the mechanism of acceleration: (i) electrothermal, (ii) electrostatic and (iii) electromagnetic. Recent trends in space exploration associate with the paradigm shift towards small and efficient satellites, or micro- and nano-satellites. A particular example of microthruster considered in this paper is the micro-cathode arc thruster (µCAT). The µCAT is based on vacuum arc discharge. Thrust is produced when the arc discharge erodes some of the cathode at high velocity and is accelerated out the nozzle by a Lorentz force. The thrust amount is controlled by varying the frequency of pulses with demonstrated range to date of 1‐50Hz producing thrust ranging from 1 µN to 0.05mN.

Mechanism of carbon nanostructure synthesis in arc plasma

Plasma enhanced techniques are widely used for synthesis of carbon nanostructures. The primary focus of this paper is to summarize recent experimental and theoretical advances in understanding of single-wall carbon nanotube (SWNT) synthesis mechanism in arcs, and to describe methods of controlling arc plasma parameters. Fundamental issues related to synthesis of SWNTs, which is a relationship between plasma parameters and SWNT characteristics are considered. It is shown that characteristics of synthesized SWNTs can be altered by varying plasma parameters. Effects of electrical and magnetic fields applied during SWNT synthesis in arc plasma are explored. Magnetic field has a profound effect on the diameter, chirality, and length of a SWNT synthesized in the arc plasma. An average length of SWNT increases by a factor of 2 in discharge with magnetic field and an amount of long nanotubes with the length above 5 μm also increases in comparison with that observed in the discharge without a magnetic field. In ad...