In cancer radiotherapy, gold nanoparticles (AuNPs) have emerged as promising radiosensitizers, which accumulate in the tumor and increase the effectiveness of external beam radiotherapy by local production of reactive oxygen species (ROS) and secondary electrons upon irradiation. At UNamur, 5 nm gold nanoparticles coated with an organic shell of polyallylamine are produced by plasma vapour deposition (AuNPs@PPAA). The AuNPs@PPAA can be conjugated to anti-EGFR antibodies (Cetuximab) (mAb-AuNPs@PPAA) which actively target EGFR-overexpressing cancer cells in vitro and in vivo. However, in vivo biodistribution studies using mirco-PET imaging have demonstrated a significant accumulation in the liver and the spleen in tumor-bearing nude NMRI mice. Therefore, prior to use the nanoconjugates in the clinic, the cytotoxicity of the AuNPs@PPAA-Ctxb should be investigated in vitro in non-cancerous human cell lines (kidney, liver and endothelial cells) and in vivo in a non-immunodeficient mouse model.