Abstract
Characterization of the radiosensitizing properties of metal-based nanoparticles.Metal based nanoparticles are of great interest as potential novel radiosensitizers and image contrast agents due to their high Z number, ease of synthesis and high mass energy co-efficient relative to soft tissue.
However, despite promising results seen both in vivo and in vitro, they have yet to be successfully implemented into clinical practice. This is a consequence of the differences seen between the physical predictions of radiosensitization and the observed biological response, along with an incomplete understanding of the mechanisms responsible.
Our aim is to define the radiosensitizing properties of metal-based nanoparticles through the development of standard operating procedures for physical, chemical and biological characterization, allowing for the systematic comparison of individual nanoparticles, specifically the Au@DTDTPA, Au@DTDTPA-Gd and AGuIX nanoparticles. Biological parameters were examined in the DU145, PC3 and PNTC2 prostate cell lines, and the U87 glioblastoma cell line.
A range of assays were used in the evaluation of these parameters. Physical characterization utilized differential centrifugation sedimentation, dynamic light scattering, UV-Vis spectroscopy and Zeta potential measurements in order to define a nanoparticles overall size, core size, and charge. This identified the nanoparticles to be small in size (sub-10 nm) and covering a range of zeta potentials.
A novel variation on the Coumarin assay was specifically developed for this study to examine the hydroxyl radical yield of ultra-small gold and gadolinium nanoparticles in the presence of irradiation. This led to the generation of a G-value, which allows for the quantitative comparison of hydroxyl radical production. As a result, nanoparticles could then be identified A range of biological endpoints were measured, using the clonogenic assay, atomic absorption spectroscopy and inductively coupled plasma atomic emission spectroscopy, and the 53BP1 assay to examine cellular survival following irradiation, cellular uptake of nanoparticles, and DNA damage and repair respectively. Cell survival data was used to calculate a dose enhancement factor for each nanoparticle in the individual cell lines, identifying the nanoparticles as radiosensitizers, while the 53BP1 assayed highlighted the ability of the nanoparticles to increase foci production, alongside inhibiting repair in some cases. The relationship between nanoparticle uptake and dose enhancement factor was also examined to determine the degree to which cellular uptake influenced a nanoparticles ability to act as a radiosensitizer.
| Date of Award | Jul 2019 |
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| Original language | English |
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| Supervisor | Giuseppe Schettino (Supervisor), Fred Currell (Supervisor) & Kevin Prise (Supervisor) |