Syntheses of gold nanoparticles and their impact on the cell cycle in breast cancer cells subjected to megavoltage X-ray irradiation

Gold nanoparticles (AuNPs) were synthesized in the presence of citrate (Au-CIT), glutathione (Au-GSH) and aminodextran (Au-DEX) in order to modify AuNPs surfaces and to increase their cellular uptake in the breast cancer cells MDA-MB-231. AuNPs were characterized with respect to their particle size, shape and colloidal stability in an aqueous solution and cell media. The mass accumulation of each AuNP type inside cancer cells was determined quantitatively, using Inductive Coupled Plasma - mass spectroscopy. The sub-cellular accumulation was studied using Transmission Electron Microscopy (TEM). It was found that gold nanoparticles applied to cancer cells were localized in cytoplasmic vesicles and that the highest uptake was shown in the presence of Au-GSH nanoparticles. The effect of AuNPs on the cell cycle was investigated using flow cytometry and Western blot analysis. The gold nanoparticles alone did not affect the cell cycle, as shown by flow cytometry. Furthermore, the cancer cells were irradiated using conventional clinically relevant high-energy X-ray radiation of 6 MV in the dose of 4 Gy. The results on cells only irradiated showed an S phase arrest six and 8 h after irradiation, and a G2/M arrest 24 and 48 h after irradiation. The irradiation of breast cancer cells treated with AuNPs has shown no significant variation in cell cycle distribution as opposed to X-ray radiation alone.