Low-Temperature Plasma Needle for Biomedical TreatmentsMichael A. Wilson,1 Timothy R. Brubaker,2 Andrea M. Mastro,3 Michael M. Micci,4 Sven G. Biln,5 and Sean D. Knecht6

1Department of Electrical Engineering; 2Department of Electrical Engineering; 3Department of Biochemistry and Molecular Biology; 4Department of Aerospace

Engineering; 5Department of Electrical Engineering; 6Applied Research Laboratory

Conclusions and Further Investigation

Abstract Results

Experimental Design

The hypothesis is that the reactive oxygen species generated in the plasma plume areresponsible for the destructive effects due to increased oxidative stress on the cells.

The generation of reactive oxygen species in the plasma plume and the subsequentoxidative stress on the cells is the proposed method of action.

Further experimentation is planned to quantify the concentration of reactive chemicalspecies and evaluate this hypothesis.

We will determine why pure helium exposure results in cell destruction. Different gases will be used in future experiments as well as longer exposure times. Larger diameter wells and a greater volume of PBS will also be used.

Three cell culture wells were exposed to helium and three wells exposed to plasma. Two wells were exposed for 60 seconds and four were exposed for 180 seconds. The mass flow rate was set to 775 mL/min. Plasma exposed cultures had voids in the cell culture that were 23 the diameter of the

voids in the helium-exposed cultures.

Cell destruction was observed to occur for a larger area in the case of the plasma jet. This indicates an additional mechanism of cell destruction is active in the low-

temperature plasma beyond the kinetic energy of the jet molecules.

An overview of the design methodology of a low-temperature plasma needle and

preliminary results investigating its efficacy in treating metastatic human breast

cancer epithelial cells is reported. Low-temperature plasma is created by flowing gas

past a high-voltage surface. This process produces ions and generates an electrically

conductive state of matter (plasma) at room temperature. High-energy collisions of

electrons with neutral particles create reactive chemical species such as NO, O3, H2O2and others which have biomedical applications.

Current cancer treatment options, such as surgery and chemotherapy, may not be

sufficient to treat metastatic cancer. Initial experiments have been conducted in which

a line of cultured metastatic human breast cancer epithelial cells (MDA-MB-231) are

exposed to the low-temperature plasma needle. The plasma needle is lowered into cell

culture dishes and the cells are exposed to plasma at different dosages. Cell

detachment was observed for plasma and helium-exposed cultures with a greater

effect observed for plasma-exposed cultures. This is attributed to reactive chemical

species generation in the plasma plume. Experiments are continuing to optimize the

treatment conditions and further this research.

(a) (b)

(c) (d)

Images of metastatic breast cancer culture MDA-MB-231 post treatment.Images are equivalent in scale. Each culture was exposed to 3-minute dosages.

(a) Helium-exposed culture, (b) Plasma-exposed culture, (c) Helium-exposed

culture, (d) Plasma-exposed culture. The voids in cell culture are larger for

plasma-exposed culture.

AcknowledgmentsThe authors wish to thank D. Sosnoski, for helping prepare the cell cultures. The BC

line (MDA-MB-231, ATCC-HTB 26 presumptive equivalent) was initially provided by

Dr. D. Welch, University of Alabama at Birmingham.

Contacts:

Michael A. Wilson Timothy R. Brubaker Andrea M. Mastro Michael M. Micci Sven G. Biln Sean D. Knecht

maw5595@psu.edu trb5084@psu.edu a36@psu.edu x0c@engr.psu.edu sbilen@psu.edu sdk149@psu.edu

This image shows the full LTP setup.

Helium is introduced to the system

using a mass flow meter. The voltage

and ground inputs are connected from

the power supply and threaded

through the tube to their respective

input locations.

The interface between the

LTP syringe interacting with a

saline sample.

Syringe

within

PEEK

Plasma

Discharge

Ground wire

wrapped around

syringe

The 22-gauge needle is 2 long and serves as the high voltage electrode. The grounding electrode is placed approximately 1/8 from the tip of the syringe. The syringe is sheathed with PEEK (polyether ether ketone). PEEK has a high dielectric strength used as a barrier to prevent arc production. The diameter of the device with the PEEK is equivalent to a 16-gauge needle. Helium flows axially through the syringe. Gas is controlled by the mass flow controller calibrated at 70 F, and 14.7 psia. The flow rate can be controlled over the range of 16775 mL/min. An Agilent 33220A Function Generator generates a 5-kHz, 2-Vpp sine wave. This wave is amplified 1000 to 2 kV by a Trek 10-40 amplifier. Increasing the voltage or mass flow rate increases the length and visible intensity of

the plasma plume.

Schematic of the LTP syringe. The HV power

supply is connected to the syringe which is

encased within the dielectric barrier (PEEK). The

gas flows through the back and out of the tip of the

syringe as plasma.