Thesis (M.Sc.) - Cairo University - Faculty of Science - Department of Biophysics

Radiation therapy (RT) is one of the most commonly used non-surgical interventions in cancer therapy. Due to reported radioresistance of many cancer cells, radiosensitizers are introduced to cancer cells as a tool to overcome such radioresistivity. There have been several attempts to use high-atomic number nanoparticles as radiosensitizer agents in cells. In this study, a novel nanoradiosensitizer composed of magnetic nanoparticle core coated with silica was successfully prepared and applied to overcome cancer radioresistance. The prepared nanoparticles were characterized by transmission electron microscope (TEM), dynamic light scattering (DLS), atomic force microscopy (AFM) and vibration sample magnetometer (VSM). The radioenhancing effects of iron oxide magnetic nanoparticles (IO-MNPs) and silica-coated iron oxide magnetic nanoparticles (SIO-MNPs) were examined in breast cancer cells (MCF7) by MTT and comet assays. MCF7 cells were treated with different concentrations of the prepared nanoparticles and exposed to electron beam and X-ray photon beam at doses of 0, 0.5, 1, 2, 4 Gy. DLS diameters of IO-MNPs and SIO-MNPs were 18 ± 4.5 nm and 164 ± 16 nm, respectively. For electron beam, MCF7 cells treated with 5, 10, 20, 40 and 80 æg /ml of SIO-MNPs and exposed to 4 Gy showed dose enhancement factor (DEF) values of 1.03, 1.32, 1.29, 1.42 and 1.64 respectively. For X-ray beam, DEF values of cells treated with 20, 40 and 80 æg /ml of SIO-MNPs and exposed to 1 Gy were 1.43, 1.65 and 2.20 respectively

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