The effect of SiO₂/Au core-shell nanoparticles on breast cancer cell's radiotherapy

Recently it has been shown that radiation dose enhancement could be achievable in radiotherapy using nanoparticles (NPs). In this study, evaluation was made to determine efficiency of gold-silica shell-core NP in megavoltage irradiation of MCF7 breath cancer cells.

Gold-silicon oxide shell-core NPs were obtained by conjugation of gold NP with amine or thiol functionalized silica NPs (AuN@SiO₂ and AuS@SiO₂). Cellular uptake and cytotoxicity of NPs were examined by fluorescent microscopy and MTT assay, respectively. MCF-7 breast cancer cells were treated with both NPs and irradiation was made with X-ray energies of 6 and 18 MV to the absorbed dose of 2, 4 and 8 Gy using Simense linear accelerator. The efficiency of radiation therapy was then evaluated by MTT and Brdu assay, DAPI staining and cell cycle analysis.

TEM images indicated that synthesized NPs had average diameter of 25 nm. Cellular uptake demonstrated that the internalization of AuS@SiO₂ and AuN@SiO₂ NPs amounted to 18% and 34%, 3 h post treatment, respectively. Nontoxicity of prepared NPs on MCF-7 cells was proved by MTT and Brdu assays as well as DAPI staining and cell cycle studies. The highest enhancement in radiation dose was observed in the cells that irradiated with radiation energy of 18 MV and absorbed of 8 Gy at NPs concentration of 200 ppm. The Brdu findings revealed that the cytotoxicity and apoptosis on MCF-7 cells are dose dependent with a significantly more death in AuN@SiO₂ (amine) exposed cells (p < .05). Analysis also revealed interruption in cell cycle by demonstrating lack of cells, in S phase in amine treated cells (AuN@SiO₂) at given dose of 8 Gy using 18 MV X-ray in comparison to thiol treated cells.

Based on the results of the study it can be concluded that the gold-silicon oxide shell-core NPs could play an effective role in radiotherapy of MCF-7 breast cancer cells.