Keep up to date with the latest research and developments from Diamond. Sign up for news on our scientific output, facility updates and plans for the future.
Related publication: Everett J., Collingwood J. F., Tjendana-Tjhin V., Brooks J., Lermyte F., Plascencia-Villa G., Hands-Portman I., Dobson J., Perry G. & Telling N. D. Nanoscale synchrotron X-ray speciation of iron and calcium compounds in amyloid plaque cores from Alzheimer’s disease subjects. Nanoscale 10, 11782–11796 (2018). DOI: 10.1039/c7nr06794a
Publication keywords: Spectromicroscopy; STXM; Alzheimer’s disease; Senile plaques; Amyloid; Iron; Calcium
Alzheimer’s disease is the most common form of dementia, yet its cause is unclear and there is no effective treatment. A hallmark of Alzheimer’s disease is the formation of amyloid plaques in the brain that disrupt its normal function. There is also an imbalance of metals, with increased levels of iron and harmful reactive iron forms being associated with amyloid plaques.
Alzheimer’s disease (AD) is the most common form of dementia, affecting ~850,000 people in the UK, with the number of cases on the increase it creates tremendous social and economic costs, and there is no cure at present.
STXM analysis at the iron L2,3-edge revealed multiple iron phases in the amyloid plaque cores ranging from ferric, mixed valence (Fe2+/Fe3+), to ferrous and even zero-valent (Fe0) iron (Fig. 1h). The presence of low-oxidation-state iron (<3+) suggests that excessive chemical reduction of iron occurred at the amyloid plaque sites. Extended damage from free radicals has been reported at sites of amyloid aggregation, so amyloid-associated toxicity to neurons may arise from this chemical reduction of iron. XMCD spectra (Fig. 1j) revealed the presence of the magnetic mixed-valence iron phase magnetite within the plaque cores4. Advanced imaging with ptychography, performed at ALS beamline 11.0.2, generated images at 2 nm resolution (Fig. 1k), revealing the morphology of a maghemite-like inclusion consistent with crystalline iron of biogenic origin (as opposed to magnetite derived from pollutants of industrial origin5.
Diamond Light Source is the UK's national synchrotron science facility, located at the Harwell Science and Innovation Campus in Oxfordshire.
Copyright © 2022 Diamond Light Source
Diamond Light Source Ltd
Harwell Science & Innovation Campus
Diamond Light Source® and the Diamond logo are registered trademarks of Diamond Light Source Ltd
Registered in England and Wales at Diamond House, Harwell Science and Innovation Campus, Didcot, Oxfordshire, OX11 0DE, United Kingdom. Company number: 4375679. VAT number: 287 461 957. Economic Operators Registration and Identification (EORI) number: GB287461957003.