RESUMO
Purpose: Nowadays, cancer is one of the most important causes of morbidity and mortality in the world. The ideal aim of radiotherapy is delivering a lethal radiation dose to tumor cells while minimizing radiation exposure to healthy tissues around the tumor. One way to increase the dose in the tumor cells is the use of high-atomic number nanoparticles as radiosensitizer agents in these cells. The aim of this in vitro study was investigating the radiosensitization enhancement potential of the dextran-coated iron oxide nanoparticles (IONPs) on HeLa and MCF-7 cell lines in irradiations with high-energy electron beams. Materials and Methods: In this in vitro study, the cytotoxicity level of dextran-coated IONPs at different concentrations (10, 40, and 80 μg/ml) was assessed on HeLa and MCF-7 cell lines. To evaluate the radiosensitivity effect, the nanoparticles were incubated with the cells at different concentrations for 24 h and afterward irradiated with different doses (0, 2, 4, 6, and 8 Gy) of 6 and 12 MeV electron beams. The cells survival fractions were obtained by the methylthiazoletetrazolium assay. Results: Toxicity results of the nanoparticles at 10 and 40 μg/ml concentrations showed no significant cytotoxicity effect. The cells survival rates in groups receiving radiation in the absence and presence of IONPs showed a significant difference. The radiosensitivity enhancement induced by the nanoparticles in MCF-7 cell line was more than it in HeLa cell line. The average of radiosensitization enhancement factor at 10, 40, and 80 μg/ml concentrations and under 6 MeV irradiations obtained as 1.13, 1.19, 1.25, and 1.26, 1.28, 1.29 for HeLa, and MCF-7 cells, respectively. When 12 MeV electron beams were carried out, the values of 1.17, 1.26, 1.32, and 1.29, 1.32, 1.35 were obtained for the cells at the mentioned concentrations, respectively. Furthermore, the significant differences were observed in radiosensitization enhancement between 6 and 12 MeV electron beams irradiations. Conclusion: Use of dextran-coated IONPs can increase radiosensitivity and consequently at a given absorbed dose more cell killing will occur in cancerous cells. In other words, these nanoparticles can improve the efficiency of electron therapy
RESUMO
Due to recent advances in nanotechnology it is now possible to accumulate high atomic-number nanomaterial such as gold nanoparticles [GNPs] in cancerous cells and take advantage of their absorbed dose enhancement property as radiosensitizing agents. This study aimed to investigate the absorbed dose enhancement factor due to the presence of PEGylated GNPs under the irradiation of an MCF-7 cancerous cell line using orthovoltage X-ray beams. We synthesized GNPs with an average diameter of 47 nm and joined them to polyethylene glycol. A total of 50 micro g/mL of the pegylated GNPs were incubated with MCF-7 cells for 1, 2, 6, 12, and 24 hours, after which we compared their cytotoxicities. Then, PEGylated GNPs [50micro g/mL] were incubated with MCF-7 cells for 12 and 24 hours and their radiosensitizing effect during 2Gy delivery of 120, 180 and 200 kVp X-ray beams were compared by the MTT assay. Cytotoxicity studies showed no significant effect of GNPs on cell viability. Significant differences in cell survival were observed between the groups irradiated with and without GNPs, which lead to an average absorbed dose enhancement factor of 1.22 +/- 0.06. According to the results, there was no radiosensitization difference due to the usage of 120, 180 and 200 kVp X-ray beams. However increased incubation time increased the dose enhancement factor. By using PEGylated GNPs we can decrease the prescribed X-ray dose, yet maintain the same level of cancerous cell killing