Low-temperature plasma needle for biomedical treatments

Michael A. Wilson, Timothy R. Brubaker, Andrea M. Mastro, Michael M. Micci, Sven G. Bilén, Sean D.

Knecht

Outline

Breast Cancer Statistics What is plasma? Low-Temperature Plasma What is a Dielectric Barrier Discharge (DBD)? DBD Implementation into our design Experimental Design Results and Conclusions Further Research

Breast Cancer Statistics January 1, 2014 - 3.1 million

women have or had a history with breast cancer

232,670 women were expected to be diagnosed that year.

Median age: 61 years old

Average 5 year survival rate increased from 75% (1975-1977) to 90% (2003-2009)

20-30% of those with diagnosed find out that the cancer has become metastatic

Current cancer treatment options, such as surgery and chemotherapy, have limitations.

Source: American Cancer Society. Cancer Treatment and Survivorship Facts & Figures 2014–2015. Atlanta: American Cancer Society; 2014.

What is Plasma?

Plasma is an electrically neutral medium of unbound positive and negative particles

Coined in 1928 by Nobel Prize winner Irving Langmuir

Not to be confused with human blood plasma

Most common state of matter found in the universe.

Two types of plasma

HTP: High-temperature (thermal)

LTP: Low-temperature (non-thermal)

LTP: Low-Temperature Plasma

Some benefits of Low-Temperature Plasma It’s easier to work with compared to HTP Many applications within the medical community

LTP is generated due to thermal equilibrium of electron self-collisions occurring faster than the equilibrium between electrons and ions This leads to high electron temperatures but very low gas

temperatures High-energy collisions of electrons with neutral particles

create reactive chemical species such as NO, O3, H2O2, OH etc.

What is a Dielectric Barrier Discharge (DBD)? An electrical

discharge that occurs between two electrodes (high voltage and ground) separated by a dielectric barrier

Provides a wide range of geometric configurations

Planar

Cylindrical

Plasma jets generate plasma in open air

Planar

Cylindrical

DBD Implementation High Voltage Electrode: 2” needle

Grounding electrode is placed approximately 1/8” from the syringe tip

The syringe is sheathed with PEEK (polyether ether ketone) plastic tubing

With the PEEK encasing the needle, the total diameter of the needle system is equivalent to a 16 gauge syringe.

The electric field allows for the formation of plasma because it accelerates electrons.

This results in high energy collisions with neutral particles that are already flowing axially which creates the reactive species

Plasma Discharge

Syringe within PEEK

Ground wire wrapped

around syringe

Experimental Design

Voltage Input

Mass Flow Controller

Optical Table

Gas Input

Ground Wire

Results and Conclusions 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.

Cell Death = Cells detaching from wells

Plasma exposed cultures had voids in the cell culture that were 23× the diameter of the voids in the helium-exposed cultures.

This indicates an additional mechanism of cell destruction is active in the low-temperature plasma beyond the kinetic energy of the jet molecules.

Hypothesis: Reactive oxygen species generated in the plasma plume are responsible for the destructive effects due to increased oxidative stress on the cells.

Further Research Further experimentation is planned to quantify the

concentration of reactive chemical species and evaluate this hypothesis.

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

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.