Fig. 3

FTIR analysis of an exemplary classic cored plaque and its compartments. A Anti-Aβ immunostaining B Areas of spectral similarity, identified by hierarchical cluster analysis (HCA), that correspond to surrounding tissue (green), corona (yellow) and core (red). C Area-normalized FTIR spectra in the range 1780–1480 cm⁻¹. The red core spectrum shows a prominent shoulder around 1628 cm⁻¹, and reduced absorbance around 1655 cm⁻¹. A difference spectrum (black) in the in the range 1700–1600 cm⁻¹ reveals minor bands around 1683 cm⁻¹ and 1694 cm⁻¹. The lipid-associated ester band around 1738 cm⁻¹ is decreased in both the corona and the core