LAUSR

The aim of this study was to assess the radiosensitivity of bismuth sulfide nanoparticles conjugated with a synthetic agonist analog of gonadotropin-releasing hormones in targeted radiotherapy for breast cancer. After synthesis and characterization of nanoparticles, cytotoxicity of nanoparticles was measured by MTT assay, and the survival fraction was determined by colony formation assay. Finally, flow cytometry was performed to identify the mechanism of radiosensitization. Characterization results determined the spherical shape of Bi2S3@BSA with an average size of 8.649 ± 1.6 nm, and Fourier transform infrared confirmed the successful binding of triptorelin to the surface of the nanoparticles. MTT test results show that the Bi2S3@BSA–triptorelin did not cause any toxicity ( P < 0.05 ) even up to 75 μg/ml. At all doses of ionizing radiation, colony formation assays showed that the nontoxic concentration of Bi2S3@BSA–triptorelin significantly increased cell death in MCF-7 cells compared to Bi2S3@BSA ( P < 0.05 ). The apoptosis test also confirmed colony formation assay results at all doses and introduced apoptosis as a mechanism of radiosensitivity produced by nanoparticles. Certainly, targeted bismuth sulfide nanoparticles can be a good candidate for increasing radiosensitivity against tumor cells.