In this study, we investigated the mechanisms of CRC cell resistance to treatments with Fe@Au nanoparticles and directly compared the responses with the Fe@Au-sensitive OECM1 oral cancer cell line. We found that Fe@Au retards growth in both CRC and OECM1 cell lines, but the Fe@Au-treated CRC cells are arrested in G1/G0 phase, rather than in the S-phase, as observed in the treated OECM1 cell line. Furthermore, we observed that the mitochondrial responses