Ionising radiation is commonly used in radiation treatment of cancer to target cancerous cells. Upon entering a cell, ionising radiation can damage DNA directly or it can excite the cellular medium. The most abundant species produced following excitation of the medium is the low energy electron (LEE). LEE's can cause significant damage to DNA but the exact mechanism of this damage is unknown. This thesis investigates the indirect damage that LEEs do to DNA fragments, with particular emphasis on the influence of the surrounding water molecules. Using ab initio Molecular Dynamics, we investigated DNA-water systems, ranging from nucleobases to nucleotides. We found that water molecules in the environment are capable of forming hydrogen bonds with or transferring protons to the DNA fragment. In all these cases, when the DNA is H-bonded to or protonated by the water molecules, the energetic barriers to DNA damage reactions are affected. In the final parts of the thesis, we extended the research and investigated chemo-radiation therapy involving the chemotherapeutic agent cisplatin. We found once again that including the water environment around the DNA-cisplatin had an effect on the reactivity of this system with LEEs. Our results highlight the significant role that water molecules can play in DNA damage processes and demonstrate that it is therefore important to incorporate explicit water molecules in any simulation of the DNA damage process.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:707538 |
| Date | January 2016 |
| Creators | McAllister, Maeve |
| Publisher | Queen's University Belfast |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
Page generated in 0.0018 seconds