The behavior of plasma-generated reactive species in plasma medicine
5 March 2018
Campus Drie Eiken, Promotiezaal Q0.02 - Universiteitsplein 1 - 2610 Antwerpen-Wilrijk (route: UAntwerpen, Campus Drie Eiken
Organization / co-organization:
Department of Chemistry
Annemie Bogaerts, Erik Neyts
PhD defence Christof Verlackt - Faculty of Science, Department of Chemistry
To date, the treatment of cancer is one of the most difficult challenges in the medical world. A lot of research is performed looking for new therapies and approaches for the selective killing of these malignant cells. The main problem lies in the ever-mutating nature of cancerous cells as they can become immune to the applied anti-cancer therapy and differentiation with the healthy surrounding tissue appears to be problematic. For this reason, more selective and efficient therapies are required. Atmospheric pressure plasmas can play a key role in the development of these efficient anti-cancer therapies, as they are able to produce biologically relevant reactive species to impose stress on the treated substrates, which will harm cancerous cells while stimulating their healthy counter-parts. However, the exact mechanisms with which the plasma-induced stress triggers the desired cellular responses is still largely unknown.
In this thesis, the role of the biologically relevant reactive species (i.e., reactive oxygen and nitrogen species, RONS) at the frontline of the plasma-assisted treatment has been investigated, in order to elucidate their initial interactions with the biological substrate. This was performed using computational methods to obtain detailed information on the expected mechanisms. The work performed can be divided in two parts: (i) investigation of the chemical modifications induced by these reactive species on various cellular components using molecular dynamics (MD) simulations; (ii) study of the transport of plasma-generated reactive species in a liquid by means of MD and a 2D fluid dynamics model (fluid), which was developed in this work. In the first part, three biological systems were considered: sugars (more specifically, D-glucose), DNA and proteins. In all three cases, oxidation of the biomolecules was observed, which was found to be case-specific and which was in agreement with multiple independent experimental observations.
Taken together, this thesis provides detailed information on the initial interactions between the plasma species and the affected (liquid covered) biological substrates. Many different plasma devices and biological substrates exist, and the initial interactions are highly dependent on the used working conditions, which define which RONS are primarily formed. Because of this, efforts should be made to elucidate the impact of the used working conditions on the generation and accumulation of biologically relevant reactive species, in order to better understand and control the initial interactions with the biological substrate. Only then are we able to better control and anticipate the biological response to the plasma treatment.