Fig 1.
Histological analysis of the first slide.
Representative regions were identified by the pathologist, including healthy areas (glands, stroma, nerves, blood vessels) and tumor-associated areas (tumor nests, necrosis, inflammatory infiltrate, malignant stroma). The colored boxes indicate the corresponding regions from which Raman spectra were subsequently acquired, ensuring that both healthy and malignant tissues were analyzed.
Fig 2.
Scanning electron microscopy images of (a) gland, (b) nerve, (c) central region of a blood, (d) inflammatory infiltrates, (e) tumor, (f) necrotic tissue and (g) stroma.
Fig 3.
Atomic force microscopy image (a) of a glandular structure, (b) nerve, (c) blood vessel, (d) inflammatory tissue, (e, f) tumor, (g) necrotic tissue and (h) stroma.
Fig 4.
(a) A typical Raman spectrum of one histological section (normalized at the highest intensity peak), (b) overlaid averaged Raman spectra (50 per tissue type) from nerve, gland, blood vessel, inflammatory infiltrate, necrosis, tumor, and stroma normalized to the phenylalanine band at 1003 cm-1 to enable the comparison between the spectra.
For improved clarity, an alternative visualization of these spectra is provided in S5 Fig of the Supplementary Material.
Table 1.
Raman peak assignment of the spectra depicted in Fig 4 [32,33].
Fig 5.
200 healthy and 200 sick averaged Raman spectra from the second slide with their variability (represented as the minimum–maximum range of spectral intensities at each Raman shift).
Insets zooms-in on the peaks that show enough variability to allow recognition between the spectra of tumor tissue and healthy tissue after baseline removal normalized to the phenylalanine band at 1650 cm-1.