ZnFe2O4 nanoparticles as radiosensitizers in radiotherapy of human prostate cancer cells

Nanopartides of high-Z elements exhibit stronger photoelectric effects than soft tissues under gamma irradiation. Hence, they can be used as effective radiosensitizers for increasing the efficiency of current radiotherapy. In this work, superparamagnetic zinc ferrite spinel (ZnFe2O4) nanoparticles were synthesized by a hydrothermal reaction method and used as radiosensitizers in cancer therapy. The magnetic nanopartides showed fast separation from solutions (e.g., similar to 1 min for 2 mg mL(-1) of the nanopartides in ethanol) by applying an external magnetic field (similar to 1 T). The ZnFe2O4 nanoparticles were applied in an in vitro radiotherapy of lymph node carcinoma of prostate cells (as high radioresistant cells) under gamma irradiation of Co-60 source. The nanoparticles exhibited no significant effects on the cancer cells up to the high concentration of 100 mu g mL(-1), in the absence of gamma irradiation. The gamma irradiation alone (2 Gy dose) also showed no significant effects on the cells. However, gamma irradiation in the presence of 100 mu g mL(-1) ZnFe2O4 nanoparticles resulted in similar to 53% inactivation of the cells (similar to 17 times higher than the inactivation that occurred under gamma irradiation alone) after 24 h. The higher cell inactivation was assigned to interaction of gamma radiation with nanoparticles (photoelectric effect), resulting in a high level electron release in the media of the radioresistant cells. Our results indicated that ZnFe2O4 nanoparticles not only can be applied in increasing the efficiency of radiotherapy, but also can be easily separated from the cell environment by using an external magnetic field after the radiotherapy. (C) 2014 Elsevier B.V. All rights reserved.