As the Fe@Au treatment diminished cell viability without inducing apoptotic or necrotic cell death, the inhibition of cell growth must therefore be considered. In our previous work, we demonstrated that Fe@Au retarded cell growth at the S-phase rather than causing cell death in OECM1 cells after a 24-hour treatment. Therefore, we next analyzed the cell cycle profile of Fe@Au-treated CRC. In Figure 5, OECM1 cells show S-phase delay, as found in our previous report.17 Intriguingly, Fe@Au caused a G1/G0 delay in CRC cells. Therefore, the decreased cell survival rate of Fe@Au-treated CRC cells is the result of growth inhibition, rather than cell death, which is consistent with our observations in oral cancer cells.