## 1 Introduction
Since nanotubes have dimensions close to the ones of the main components of the natural cellular matrix, their mechanical properties are similar to those of the protein structures of a living organism [26]. Nanotubes are able to mimic collagen (the fibrillar protein of the extracellular matrix) due to recurring defects in the structure of the tubes, similar to the structure of collagen [27]. Depending on the type of biological tissues being restored, multi-walled, single-walled carbon nanotubes (SWCNT) and network-like structures are used in polymer or biopolymer matrices of polycaprolactone, chitosan, polylactide, hydroxyapatite, etc. [28; 29; 30; 31; 32]. The use of frame structures from SWCNT in bioelectronics and engineering of biological tissues improves cell population kinetics: their adhesion, proliferation and differentiation [18]. This is especially important for the engineering of cardiac tissue, since nanotubes provide the electrical conductivity of the material they fill in, while the heart generates electric current, and the heart tissue allows it to pass [33; 34]. Thus, implants for stimulating and restoring the structure of the heart tissue must have electrical conductivity [35]. The electrical conductivity of implants plays an important role in the survival of the seeded cells and the efficient signal transmission between two adjacent cells [36]. In addition,nanotubes have high strength, which is important for the restoration of cardiac tissue under stress [37]. Matrix materials can also be chosen to improve characteristics of 3D structures. Studies indicate that using albumin and collagen proteins for these purposes is promising. Albumin molecule has two modifications of the isomer, which are an ellipsoid of revolution and an irregular triangular prism [38]. Albumin is capable of cross-linking under the action of laser radiation using amino acid residues on the outer surface of the molecule [16; 39]. This indicates the possibility of creating nanocomposite globules with SWCNT. Albumin is widely used to create implants that interact with blood because it inhibits platelet adhesion and prevents thrombus formation [40]. Collagen is the main protein in the connective tissue produced by fibroblasts. In case of damage to biological tissue, collagen is involved in the restoration and renewal of cells, i.e., it serves as a reserve of amino acids [41]. Fibrillar collagen molecules have a similar structure to SWCNT, especially thin ones. The addition of collagen to implants ensures cell proliferation [42]. The surface of collagen filaments promotes the adhesion of cells and molecules, for example, growth factors, due to the presence of a large number of ligands and functional groups [43; 44]. We have previously demonstrated methods of laser formation of SWCNT frame structures in biopolymer matrices [18; 45]. The mechanisms of SWCNT binding to each other [18] and to amino acid residues of proteins [16; 46] were determined. When forming frame materials for tissue engineering, it is very important to control their structure, namely porosity. In case of using pulsed laser radiation to create 3D structures, it is necessary to be guided by nonlinear mechanisms of laser pulses absorption in media based on nanotubes [47]. It is known that when laser pulses hit carbon nanotubes, electromagnetic radiation is absorbed and its energy is converted into heat, which provokes the appearance of the vapor shell around SWCNT and their bundles. It promotes the formation of pores in the material. Such materials must be porous to allow the proliferation of cells, nerve fibers and blood vessels during implantation. However, the porosity can be influenced by the concentration of nanotubes as well as their type [48]. In this work, the structure and properties of frame nanocomposites of albumin and collagen proteins were investigated depending on the type and concentration of SWCNT. Such nanocomposites were created by laser action on a water-protein dispersion with carbon nanotubes.