Figure 3.

Second-derivative infrared spectra, principal component analysis (PCA), and hierarchical cluster analysis (HCA) model discriminating the three amyloid types. (A) Second-derivative absorbance spectra of κ light chain (red lines), λ light chain (green lines), and transthyretin (blue lines) cardiac amyloidosis in the amide I region (1700–1600 cm⁻¹). (B) The dendrogram of the HCA shows clear clustering of the distinct amyloid types: transthyretin (blue lines), κ light chain (red line), and λ light chain (green lines). (C) Score plot of the first two components of the PCA model in the specific spectral region of 1646–1642 cm⁻¹ demonstrating visible clustering between the distinct amyloidosis types: κ light chain (red dot), λ light chain (green dots), and transthyretin (blue dots).