FIG. 3.

Study of brain tissues and time-lapsed imaging by synchrotron-based IR microscopes. (A) Amyloid plaques in human AD tissue show elevated β-sheet and accumulation of Cu and Zn ions. (a) bright field; (b) Thioflavin S staining of amyloid plaques; (c) infrared spectra of Thioflavin-positive (red), Thoflavin-negative (black), and purified Aβ peptide in vitro (green). (d) synchrotron x-ray fluorescence spectra of Thioflavin-positive (red) and Thioflavin-negative (black). Scale bar 100 μm. Reproduced with permission from Miller et al., J. Struct. Biol. 155(1), 30–37 (2006).⁵⁷ Copyright 2006 Elsevier. (B) Increased lipid contents were detected surrounding and within the dense core of amyloid plaques. (a and b) bright field; (c) IR spectra along the yellow line in (a); (d) amide I β-sheet 1630 cm⁻¹; (e) plaque density 1390 cm⁻¹; (f) symmetric CH₂ stretching mainly from lipids 2850 cm⁻¹; (g) stained after FTIR imaging with Congo red (plaque core) and Hematoxylin blue (nuclei). Scale bar 50 μm. Reproduced with permission from Liao et al., Analyst 138(14), 3991–3997 (2013).⁶⁰ Copyright 2013 The Royal Society of Chemistry. (C) An increase in anti-parallel β-sheet structure was detected in live cells expressing mutant SOD1-YFP, suggesting the formation of oligomeric structures. All scale bars are 10 μm. Reproduced with permission from Miller et al., Biochim. Biophys. Acta 1828(10), 2339–2346 (2013).⁵⁵ Copyright 2013 Elsevier. (D) β-sheet detected in live cell 40 min responding to severe heat shock. Reproduced with permission from Mitri et al., Anal. Chem. 87(7), 3670–3677 (2015).⁶¹ Copyright 2015 American Chemical Society.