In vitro radiosensitization by gold nanoparticles during continuous low-dose-rate gamma irradiation with I-125 brachytherapy seeds.

This communication reports the first experimental evidence of gold nanoparticle (AuNP) radiosensitization during continuous low-dose-rate (LDR) gamma irradiation with low-energy brachytherapy sources. HeLa cell cultures incubated with and without AuNP were irradiated with an I-125 seed plaque designed to produce a relatively homogeneous dose distribution in the plane of the cell culture slide. Four sets of irradiation experiments were conducted at low-dose rates ranging from 2.1 to 4.5cGy/h. Residual γH2AX was measured 24h after irradiation and used to compare radiation damage to the cells with and without AuNP. The data demonstrate that the biological effect when irradiating in the presence of 0.2mg/ml concentration of AuNP is about 70%-130% greater than without AuNP. Meanwhile, without radiation, the AuNP showed minimal effect on the cancer cells. These findings provide in vitro evidence that AuNP may be employed as radiosensitizers during continuous LDR brachytherapy. FROM THE CLINICAL EDITOR: In this basic science paper, the application of gold nanoparticles as radiosensitizing agents for low dose rate gamma radiation therapy is discussed, demonstrating efficacy in cell culture models.