To validate the interaction of RONS produced in direct CAP or PTM with proteins, I have performed both wet laboratory experiments, as well as computational simulations. Firstly, I learned the basics of non-reactive molecular dynamics (MD) simulations, using the GROMACS package, implementing the CHARMM27 all-atom force field. Using the GROMACS package, I have developed the force fields for oxidized amino-acids based on literature. To understand the fluid dynamics of reactive species generated by plasma, I became familiar with 3D fluid dynamics modeling. After learning the MD simulations, I checked the effect of plasma on various proteins.
Firstly, we track the plasma jet delivery of RONS into a tissue model target. Our results imply that the flux of UV photons from plasma jets is important for delivering RONS through seemingly impenetrable barriers such as skin.
Secondly, we explored the importance of RNS in PTW for their bactericidal effect. Interestingly, we observed that with increasing RNS content in PTW, more deactivation of bacteria was observed. Further, we investigated the CAP effect on the deactivation of thermophilic bacteria to understand the CAP potential in the food industry. We treated thermophilic bacteria protein with dielectric barrier discharge (DBD) plasma operating in air. The structural changes of MTH were analysed upon CAP treatment. Additionally, we performed MD simulations to determine the stability of both the native and oxidised protein.
We also studied the effect of plasma treated media (PTM) and plasma treated water (PTW) on two different pancreatic ductal adenocarcinomas (MiaPaca-2, BxPc3) and pancreatic stellate cells (PSCs) (hPSC128-SV). Our study revealed that PTM and PTW have a similar efficacy to kill pancreatic cancer cells, while PTW is slightly more effective in killing PSCs as compared to PTM. In another study, we used PTW to treat non-small lung carcinoma (NSCLC) through oral administration. PTW shows favorable anticancer effect on chemoresistance xenograft mice.
We also investigated the effect of RONS on the NOX and Bacteriorhodopsin (BR)G protein-coupled receptor (GPCR)proteins.
Finally, we studied the role of catalase protein in CAP treatment.Our study concludes that the enzymatic activity of catalase decreases after plasma treatment, but this decrease is not strong enough that it can completely inhibit the catalase cellular function (to metabolize H2O2) in cancer cells.
Throughout the project, I used different dissemination channels for my research. The non-industrial nature of the project implied that the main dissemination method was published in scientific journals and participation in conferences. 4 paper has been published SCI indexed journals, while 3 manuscripts are currently under preparation. We succeeded in publishing both in specific journals targeting the plasma community (Journal of Physics D: Applied Physics), and in journals of wider scientific interest (Scientific Reports, and RSC Advances). The aim of this was to bring more attention to the state-of-the-art of plasma research from different fields of science, including wide chemistry, biology and engineering readership. My results were also presented to the scientific community in the form of 7 conference contributions at the major domestic and international conferences in the plasma domain as invited lectures, tutorial lectures, oral presentation and posters.
