Fig. 3

A Cell cytotoxicity of different concentrations of Gel-FeS NPs (0‒430.0 µg/mL) on MARC-145 cells. B The cellular internalization experiment of Gel-FeS NPs. After MARC-145 cells were incubated with different concentrations of Gel-FeS NPs (0‒340.0 µg/mL), the cells were collected at the indicated time points, and the content of Fe in the cells was detected by ICP-MS. C Analysis of intracellular ferrous iron release from Gel-FeS NPs by the ferrous ion colorimetric kit after incubating MARC-145 cells with different concentrations of Gel-FeS NPs (0‒340.0 µg/mL) and collecting the cells at the indicated time points. Control group: cells treated with the DMEM (2% FBS). Error bars represent the standard deviation from three repeated experiments