Although the nanoparticles caused a dose-dependent cytotoxic response both in the CRC and OECM1 cells after 48 hours, the CRC cells were at least an order of magnitude less sensitive,based on IC50 dosage, to Fe@Au treatment than OECM1 cells. In the subsequent experiments, we applied doses of 10 μg/mL and 50 μg/mL of Fe@Au to treat OECM1 and CRC cells respectively; these concentrations are close to the half-maximal inhibitory doses for the cell lines. Using a single dose of Fe@Au in different CRC cells facilitates the scientific comparison between different cell lines and different experiments.