Uptake and accumulation of DMSA-SPION into cells. (A) MCF-7 living cells visualized by bright field microscopy. (a) Control cells. (b) Cells incubated with 0.4 mg ml−1 SPION for 24 h. Scale bar represents 10 μm. (B) Cells incubated with 0.4 mg ml−1 SPION for different time, stained with Prussian blue reaction and visualized by bright field microscopy. (a) Control cells. (b-i) Cells incubated for 0.5, 1, 3, 6, 12, 24, 48 and 72 h, respectively. Scale bar represents 10 μm. (C) Intracellular iron content quantification by ferrozine assay (expressed as weight of iron per cell), after 24 and 48 h of incubation. (D, E) Untreated and incubated MCF-7 (area, red filter), cell with DMSA-SPION. Representative images (D) and quantitative box-plot of 100 cells per treatment (E). Details of x-axis: 1) Untreated cell only (background red filter), 2) Untreated, cell only (blue filter), 3) Cell + SPION (total SPION), 4) Cell + SPION (total cell area, blue filter).