Fig. S3.
(A) High-angle annular diffraction and (B) dark-field TEM micrographs showing spherical magnetic nanoparticles in brain tissues. (C) Fe−L2,3 EELS spectra of nanoparticles identified in the selected areas (boxes 1 through 4) showing the absence of any preedges (see hematite, goethite, and ferrihydrite preedge at ∼708.8 eV), Fe−L3 edges centered at 708 eV, and broad Fe−L2 features characteristic of magnetite, compared with the Fe−L2,3 EELS spectra (D) of standard magnetite, siderite, hematite, goethite, and two-line ferrihydrite.