## 2 Materials and Methods
### Technique for the Manufacture of Dispersed Media and the Formation of Nanocomposites  
Initially, homogeneous dispersed medium (dispersion) was prepared with one of the SWCNT types and one of the proteins in water. Tridistilled water was used as a solvent for dispersed media. The dispersed medium in the liquid state served as ink for the fabrication of a three-dimensional structure of nanocomposites. To prepare the dispersed medium, SWCNT1 or SWCNT2 were added to water. The final concentration of CNTs in the samples was 0.01 or 0.001 wt.%. These concentrations were chosen to provide a compromise between the biocompatibility of nanocomposites and their structural and electrophysical properties [47].  
Initially, the aqueous dispersion of SWCNT was subjected to powerful ultrasonic action of a probe homogenizer for 45 min at a power of 40 W. This was necessary to break the van der Waals forces between SWCNT in bundles. As a result, the dispersions mainly contained isolated nanotubes. Next, albumin or collagen powder was immediately added to the aqueous dispersion of nanotubes, since proteins acted as surfactants for SWCNT. In dispersions, it was possible to reach a maximum concentration of albumin \(\sim\)20 wt.%, and collagen \(\sim\)1 wt.%. After that, the composition was dispersed in an ultrasonic bath at a lower power (<10 W) for 60 min. Thus, the structure of protein molecules was not damaged.  
To form nanocomposites in a three-dimensional form, the obtained disperse medium in a liquid state was applied in layers. The layers of SWCNT1/SWCNT2 with albumin alternated with layers with collagen. Each layer of the dispersion was transformed from liquid to solid state under the action of laser radiation using the developed laser setup (Figure 1). After drying the dispersion layer, the volume of dispersion necessary for the formation of the next layer was poured on it, after which laser treatment was performed again. Physical mixture of components without laser treatment does not promote the formation of a bonded nanotubes framework; this does not ensure the formation of nanocomposites. Exposure to electromagnetic laser radiation is necessary for the formation of strong electrically conductive nanocomposites [16; 47]. The setup made it possible to apply uniform layers of dispersion (1) in a container (2) by an extrusion method using a nozzle (3) connected to a syringe (4). The positioning of the head (5) with the nozzle (3) was carried out using the movement system based on stepper motors of a three-coordinate system (X, Y, Z) on a massive bed. The movement accuracy reached 0.1 \(\upmu\)m at a speed of 0.01 to 5 m/s. The head movement trajectory (5) was set using a computer 3D model. Moreover, an optical fiber (6) with a collimator (7) was connected to the head (5). Thus, the setup made it possible to move the laser radiation along a given trajectory along the deposited layers of dispersion (1) in the container (2). However, in this experiment, we used unfocused radiation (8), which moved along the vertical axis depending on the number of deposited layers. Plane-parallel radiation covered the entire area of the dispersion in the container (2). For this purpose, a diode laser (9) with a wavelength in the near IR range of 810 nm was used. The spatial profile of the laser radiation had a Gaussian shape. The setup contained a 630 nm pilot laser to illuminate the main IR radiation. The radiation power was varied from 0.1 to 3 W depending on the temperature of the layers. Temperature detection was carried out using an IR sensor (10) connected to a microcontroller (11), which changed the current supplied to the laser diode (12) in real time. Such construction makes it possible to control the heating of the liquid to the desired temperature, excluding the destruction of the protein structure. The creation of nanocomposites took place in the temperature range 40-55 \({}^{\circ}\)C. A heating table was used to preheat the dispersion (13).