## 3 Results and Discussion
### Raman Spectroscopy of Nanocomposites  
The structure of SWCNT and proteins in nanocomposites were studied by Raman spectroscopy. (Figure 3). The presence of a \"hump\" in the spectra is explained by the contribution of the proteins fluorescence that occurs when they are treated with radiation in the visible region of the spectrum. The spectra of nanocomposites contain peaks characteristic of SWCNT: RBM-band (110-160 cm\({}^{-1}\)), D-band (\(\sim\)1311 cm\({}^{-1}\)), and 2D-band (\(\sim\)2590 cm\({}^{-1}\)), the intensity of which is in relation to G-band (\(\sim\)1590 cm\({}^{-1}\)) indicates the absence of damage in the structure of nanotubes (twisting, fractures, etc.). The splitting of the G-band corresponds to the manifestation of the semiconducting properties of nanotubes. The degree of defectiveness is different for the two types of nanotubes. It is known that the bands's intensity ratio \(\rm I_{D}/I_{G}\) makes it possible to estimate the defectiveness of carbon nanotubes. Defectiveness is understood as a wide range of disturbances in the structure of the nanotubes surface, from vacancies of carbon atoms to chemical interaction with other substances. In the case of the nanocomposite based on SWCNT1 with a concentration of 0.001 wt.%, an \(\rm I_{D}/I_{G}\) ratio of \(\sim\)0.129 was obtained (Figure 3a). This value is presumably associated with the interaction of nanotubes with proteins during the creation of nanocomposites. Figure 2: TEM images of SWCNT1 (**a**) and SWCNT2 (**b**) (green arrows indicate isolated nanotubes, yellow arrows indicate their bundles) and the appearances of the nanocomposites obtained with SWCNT1 (**c**) and SWCNT2 (**d**). For the spectrum of the nanocomposite based on SWCNT1 (0.01 wt.%), a decrease in defectiveness to I\({}_{\rm D}\)/I\({}_{\rm G}\)\(\sim\)0.116 was obtained (Figure 3b), since an increase in the concentration of SWCNT leads to an increase in the probability of the contacts formation between nanotubes in defect areas. When laser irradiated, SWCNT's defects behave like chemically active hotspots due to a decrease in thermal conductivity. For the spectrum of the SWCNT2-based nanocomposite (0.001 wt.%), the intensity ratio of the I\({}_{\rm D}\)/I\({}_{\rm G}\) bands for the sample was \(\sim\)0.076, which is lower in comparison with the SWCNT1 nanocomposite (0.001 wt.%). Since SWCNT2 initially had greater defects, the number of defects decreased during the formation of a nanocomposite with SWCNT branched 3D networks. For the spectrum of the SWCNT2-based nanocomposite (0.01 wt.%), the intensity ratio of the ID/IG modes was minimal, \(\sim\)0.035. The smallest defectiveness of the SWCNT2-based nanocomposite (0.01 wt.%) can be explained by the formation of branched 3D networks from isolated nanotubes and their bundles. Figure 3c,d shows that the radial RBM-band (110-160 cm\({}^{-1}\)) is represented by several peaks, which indicates the presence of SWCNT2 of different diameters in the nanocomposite. SWCNT1-based nanocomposites had a narrow RBM-band with a high intensity, which is associated with a small spread of nanotube diameters. The spectrum line in the interval between the radial and D bands passes well above the zero mark, which indicates the presence of proteins in the composite. Under the influence of laser radiation, by means of which the nanocomposites were obtained, the proteins albumin and collagen underwent denaturation (by heating the dispersion with laser radiation above 55 \({}^{\circ}\)C). The degree of damage to the proteins structure can be assessed by the presence of peaks in the amide group: the presence of a weak peak at 1656 cm\({}^{-1}\) (Amide I, presence of C=O bonds) indicates damage in the tertiary/secondary structure of proteins. The Amide II band is weakly manifested in the Raman spectrum and, therefore,  
Figure 3: Raman spectra of SWCNT1 (**a**,**b**) and SWCNT2-based (**c**,**d**) nanocomposites with nanotube concentrations of 0.001 (**a**,**c**) and 0.01 (**b**,**d**) wt.%. is not used for analyzing the structure of proteins.