Fig. 2. STXM images, metal maps, and copper and iron x-ray absorption spectra from a subject Y amyloid plaque.

(A) STXM image showing the overall plaque morphology. (B) Cu⁺/Cu⁰ map. (C) Iron map. (D) Composite STXM image showing plaque morphology (blue), Cu⁺/Cu⁰ (red), and iron (gray) content. (E) Copper x-ray absorption spectrum from the copper area highlighted in (B) (cyan trace) and a Cu⁰ reference (black trace). Reprinted from Jiang et al. (42) with the permission of AIP Publishing. The energies corresponding to Cu²⁺ and Cu⁺/Cu⁰ content are shown by the dashed and dotted-dashed lines, respectively. Asterisks highlight extended x-ray absorption fine structure (EXAFS) indicative of metallic copper (Cu⁰). (F) Iron x-ray absorption spectra from the areas highlighted in (C).