Some of the most useful tools at the hands of a surgeon operating on a cancer patient are energy sources such as Lasers, monopolar and bipolar electrocautery. Those tools deliver heat (they increase the temperature) to the targeted (usually diseased tissue such as cancerous etc.) tissue, cutting it, coagulating (burning and stopping the blood flow) and ablating it (evaporating it). Despite their wide use, there are two major challenges with thermal energy tools, namely non-selectivity and collateral damage. Collateral damage translates into longer recovery time and pain, and into the possibility of serious injury to critical tissue and in some cases abandonment of treatment. It will therefore be highly desirable to have a surgical energy source that does not cause collateral thermal damage and can selectively treat the cancerous tissue without affecting the healthy one. Such a source would have significant implications in the surgical treatment of cancer. It would result in less pain and faster recovery times for the patient and in the ability to cure forms of inoperable cancer. This project deals with a new type of energy known as cold atmospheric plasma (CAP) which has shown promising results exhibiting almost no thermal collateral damage and also selectivity in treatment. CAP is inexpensive, easy to work with and opens up the possibilities of biomedical applications. Because CAP is non-thermal, the absence of collateral thermal damage is well understood and intuitive. The selectivity aspect of CAP though, is not well understood and this is the focus of this proposed research. The overall objective of the project is to aid in the understanding of the phenomenon of the selectivity of CAP. It achieves that by developing numerical models that help understand the complex mechanisms of CAP with tissue and by conducting biological experiments where cancerous and non-cancerous cells are treated with CAP. This work showed that CAP could be understood as interacting with tissue in two ways that are interconnected. The first being an electric field and the second being a slew of reactive oxygen and nitrogen species (RS) such as NO, OH, O, H2O2 etc. The electric field causes the cells to open up (through a phenomenon known as electroporation) and that allows the RS to enter into the cells. Once a sufficient number of RS enter, the cell undergoes apoptosis (controlled and slow death). The work of CAP-CANCER showed that it is possible to adjust the plasma parameters to increase the effects electroporation and therefore apoptosis for cancerous cells. Furthermore, it also showed that cancerous cells are more susceptible to electroporation than healthy cells and this could account for the selectivity of the treatment.
