Fig. 1

Characterization of the MOF nanoparticles. a Hydrodynamic size of MOF, BSO@MOF, and BSO@MOF-L. b Zeta potential of MOF, BSO@MOF, and BSO@MOF-L (n = 3). c-e Transmission electron microscopy images of MOF, BSO@MOF, and BSO@MOF-L (scale bar: 150 nm). f Changes in size of BSO@MOF-L in PBS or culture medium, indicating good stability. g The release of iron from BSO@MOF-L at different pH values. MOF metal-organic framework; BSO buthionine sulfoxide amine; PBS phosphate-buffered saline