Master of Science (Research)
School of Chemistry
Stewart, Callum Arthur Charles, An investigation into the tailoring of bismuth oxide nanoceramic with a biomedical application as a high Z radiation enhancer for cancer therapy, Master of Science (Research) thesis, School of Chemistry, University of Wollongong, 2014. http://ro.uow.edu.au/theses/4325
Various materials, such as gold and tantalum oxide, have been researched for their use as radiation enhancers or “radiosensitisers” with high Z elements showing a high proficiency. Bismuth oxide nanoceramics have been utilised in many applications but their effectiveness as a high Z radiosensitiser has not yet been examined. The aim of this investigation was to assess the effectiveness of Bi2O3 nanoceramics as radiation enhancers and to tailor the biochemical activity through oxygen deficiencies. These were tested on 9L Gliosarcoma and Madin-Darby canine kidney (MDCK) cell lines. The nanoceramics were characterised using X-ray diffraction and electron microscopy to confirm 50-80 nm nanoplatelet morphology and monoclinic crystal structure. The surfaces of the nanoceramics were then examined for atomic composition which showed oxygen reduction of 1.25 weight% in the argon annealed nanoceramic. Different biological behaviours were observed between the two samples. The air annealed samples showing cytotoxicity, while the argon annealed samples demonstrated cell proliferation and biocompatibility for MDCK and 9L respectively. Bioactivity was linked to the generation and scavenging of reactive oxygen species (ROS), with the effects dictated by available oxygen deficiencies and exposure time. The nanoceramics were then examined under 125 kV and 10 MV radiation energies. Under the 125 kVp energy, both the air and argon nanoceramics had the same calculated sensitisation enhancement ratio (SER). The more effective argon sample was examined under a 10 MV field and demonstrated an SER of 1.25. The platelet structure of the nanoceramics results in a kV SER higher than other compounds published, but it hinders the 10 MV effectiveness due to the aggregate size trapping the produced electrons in the material. Future research would involve optimising the morphology for smaller platelets with increased oxygen deficiencies, examination at multiple radiation energies, and incorporation into a theranostic system.