## 3 Results and Discussion
### Raman Spectra of Colon Tissues and Colorectal Polyps  
Figure 5 represents the average Raman spectra (mean \(\pm\) SD) of normal colon tissue, adenomatous colorectal polyp, and adenocarcinoma samples collected with handheld, modular, and laboratory Raman instruments. Table S2 summarizes the contribution of biological macromolecules in the Raman spectra of normal colon tissue based on the spectra measured for the reference compounds using the DXR SmartRaman instrument. Positions, widths, and relative intensities of the bands in the spectra of normal colon tissue varied for the Raman instruments used in this work. The tissue bands in the Raman spectrum measured with DXR SmartRaman were mostly well resolved and indicated the main biochemical constituents. By contrast, two portable devices possessed spectra with less-resolved bands. Comparing the modular and handheld devices, it is clear that i-Raman Plus measured spectrum with narrower and more pronounced signals than Ahura FirstDefender. For example, in the spectrum of normal colon tissue obtained with i-Raman Plus, the signals at 1002, 1032, 1125, 1175, 1207, and 1340 cm\({}^{-1}\) were narrow and well resolved, while in the spectrum measured with Ahura FirstDefender, the corresponding signals were broader and sometimes appeared as shoulders. The spectra of normal colon tissue have a number of bands characteristic of the main biochemical components: proteins (including collagens), lipids, nucleic acids, and polysaccharides [5; 6; 43; 44; 45; 46; 47; 48; 49; 50]. In addition, many bands include contributions from several biochemical components, making their assignment difficult. Moreover, the contributions of individual components will be far from identical and may differ in their content and location in the tissue sample. The highest contribution to the Raman spectrum of colon tissue comes from protein vibrations. Indeed, the bands observed in the DXR SmartRaman spectrum for normal colon tissue at 1657, 1446, 1335, 1267, 1209, 1124, 1034, 1004, 940, 851, 832, 744, 666, 645, and 622 cm\({}^{-1}\) were similar to those obtained for HSA (Table S1). These bands are characteristic for vibrations of a protein backbone and amino acid side chains [32; 33] and can be used as protein markers. The characteristic bands of nucleic acids  
Figure 5: The average Raman spectra of tissue samples collected with handheld (**top**), modular (**middle**), and laboratory (**bottom**) Raman instruments: (a) normal colon tissue; (b) adenomatous colorectal polyp; (c) adenocarcinoma. The standard deviation (SD) intervals are shown as gray space. were much less pronounced and may have contributed at 1582, 1335, 1486, 1335, 1303, 1243, 1175, 1095, 880, 786, 726, and 666 cm\({}^{-1}\)[29; 30; 31]. Some of these bands overlapped with the mentioned protein bands, reducing the number of DNA marker bands suitable to follow tissue nucleic acids. Similarly, collagen vibrations contribute to the colon tissue spectrum at 1657, 1636, 1553, 1396, 1381, 1335, 1267, 1245, 1082, 1004, 960, 940, 880, 862, 823, 786, 760, 694, 646, and 622 cm\({}^{-1}\), with many of these bands being common to collagens [36; 37; 38] and globular proteins [31; 32; 33; 34]. Most of the sodium hyalurone bands do not correspond in position to the tissue peaks, except the bands at 1656, 1267, 1209, and 1124 cm\({}^{-1}\)[41; 42]. More pronounced compounds like proteins contribute to these bands, making them difficult to use for identifying hyalurone in colon tissue. Hyaluronate macromolecules usually form complexes with other biological molecules or are included in the structure of proteoglycans, so their Raman properties can differ significantly from the properties of pure sodium hyalurone. Nevertheless, the C-O and C-C stretching bands in the region of 950-1150 cm\({}^{-1}\) are attributive to tissue polysaccharides like glycogen and GAG [41; 42; 48], and the intense vibration band of the sulfate groups at 1064-1070 cm\({}^{-1}\) is suitable for the identification of sulfated GAG [42].