In vitrogold nanoparticle radiation sensitization effects in conjunction with a 2.5 megavoltage photon beam in...

Gold nanoparticle (GNP) enhanced radiosensitization was studied across three tumour cells lines that vary in radiosensitivity for a 2.5 MV photon beam. The intrinsic sensitivity of the cell lines is studied for the effects of GNPs. Three cell lines which exhibit differences in radiation response: prostate adenocarcinoma (PC-3), breast adenocarcinoma (MDA-MB-231), and cervical adenocarcinoma (HeLa) were used to determine thein vitrodose enhancement effects of GNPs combined with a 2.5 MV photon beam. Cells were incubated with 20 μg ml^-1GNPs for 24 h, and any extracellular GNPs were washed out prior to each assay. The cellular uptake of GNPs was assessed with inductively coupled plasma optical emission spectroscopy (ICP-OES). Clonogenic assays were conducted to assess cell viability after irradiation. The biological damage was assessed through DNA damage using terminal deoxynucleotidyl transferase dUTP nick end labeling assay (TUNEL). The production of reactive oxygen species (ROS) was assessed using CellRox assays. The enhancement factor when cells were irradiated in the presence of GNPs with 2.5 MV was 1.35 ± 0.46 for HeLa, 1.35 ± 0.11 for MDA-MB-231, and 0.99 ± 0.08 for PC-3 cells. On average, the level of DNA damage increased in MDA-MB-231 and HeLa cells when irradiated with 2.5 MV in the presence of GNPs. Increase in the ROS levels were detected in all cell lines when irradiated in the presence of GNPs. The enhancement effects with GNPs combined with a 2.5 MV photon beam were dependent on the cell line. The enhancement factor for HeLa and MDA-MB-231 supports further investigation of intermediate photon-energy beams in combination with GNPs. The combination of using a conventionally lower energy megavoltage beam with gold nanoparticles may become applicable in the clinical setting due to reduced skin dose and enhanced secondary electron production.