Fig. 1

Detection of iron in macrophages using sulfide silver autometallography. (A) Scheme of workflow including three main steps: iron exposure, in which the cells (J774A.1) are subjected to a treatment with iron solution; sulfidation, in which the cells are incubated in a sulfur solution allowing iron sulfide (Fe–S) to form; and silver precipitation, in which silver atoms (Ag) reduced from silver ions (Ag+) accumulate on Fe–S AMG nanocrystals. Gradient staining of J774A.1 cells treated with increasing concentrations of iron using ssAMG (B) and Prussian blue (C).