Interrogating the effect of thawing on Fe speciation in human tissue using XANES

Recent studies suggest that iron and neuroinflammation are key components of AD pathology. Specifically, ferrous Fe2+ can cause oxidative stress, a possible a mechanistic link to disease progression. Correlative ex vivo MRI can detect iron-containing microglia in AD hippocampi, but whether this iron is ferrous is unknown. Synchrotron X-ray absorption near edge spectroscopy (XANES) can quantify iron oxidation state in frozen human brain samples. However, tissue thawing during the long scans might affect the oxidation state. Here, we implement the necessary hardware to interrogate that question and present preliminary evidence that, as specimens thaw, less redox-active ferrous iron is measured.