Room: AAPM ePoster Library
Purpose: To synthesize samarium doped titanium dioxide nanoparticles (Ti(Sm)O2-NPs) and employ it as an efficient radiosensitizing agent. We investigated the potential applications of this nano-compound in radiation therapy.
Methods: Ti(Sm)O2-NPs were synthesized by a solvothermal method. A549 and DU145 cancer cell lines were used in this study. The cellular uptake of NPs was analyzed using a flow cytometry technique. A clonogenic assay was performed to evaluate the cytotoxic effect of Ti(Sm)O2-NPs with 6 MV X-rays. Subsequently, the generation of reactive oxygen species (ROS) was measured using 2',7'-dichlorofluorescin diacetate (DCFDA). In addition, computed tomography (CT) images of Ti(Sm)O2-NPs were acquired using a phantom to assess their image contrast properties.
Results: The synthesized Ti(Sm)O2-NPs were approximately 13 nm in diameter as confirmed using a transmission electron microscope. The cellular uptake of NPs was determined by the increased side scattering signals in flow cytometry. There were no significant decreases in cell viability up to 200 µg/ml of both undoped TiO2-NPs and Ti(Sm)O2-NPs. The cytotoxic effects of the combination of Ti(Sm)O2-NPs and X-rays were significantly higher by about 10% than that of undoped TiO2-NPs and X-rays for both A549 and DU145 cells. Consistently, DCFDA assay showed the increase of intracellular ROS by Ti(Sm)O2-NPs upon X-ray irradiation compared to TiO2-NPs. Moreover, the CT indicated higher beam attenuation by the inclusion of NPs with samarium.
Conclusion: While very small amounts of samarium were incorporated to TiO2-NPs, Ti(Sm)O2-NPs induced higher dose enhancement effects and higher ROS generation than undoped TiO2-NPs. Further studies will be necessary to elucidate the detailed biochemical effects of Ti(Sm)O2-NPs, however, our findings suggest the doping of samarium to TiO2-NPs could improve their X-ray absorption efficiency, rendering them as excellent theranostic agents.