Репозиторий Университета

© 2020 Elsevier Ltd A laser technology has been developed for fabricating structures from composite layers based on biopolymers: albumin, collagen, and chitosan with single-walled carbon nanotubes (SWCNT). The structures are intended for cardiovascular devices and tissue-engineered implants. This is evidenced by the results of studies. The composite layers were fabricated due to the phase transition of biopolymers and SWCNT aqueous dispersion under the influence of laser pulses. At the same time branched 3D networks of SWCNT were formed in the biopolymer matrix. The threshold energy fluence of laser pulses was determined (0.032–0.083 J/cm2) at which a bimodal distribution of pores was observed. The calculation of contact resistances between nanotubes at percolation units of 3D networks (20–100 kOhm) was carried out. Composite layers fabricated by laser demonstrated conductivity values that were higher (12.4 S/m) than those for layers by thermostat (4.7 S/m). The maximum hardness of the composite layers with SWCNT (0.01 wt%) by laser was 482 ± 10, 425 ± 10, and 407 ± 15 MPa for albumin, collagen and chitosan, respectively. The hardness of the thermostat layers was less than 100 MPa. The viability of endothelial cells in composite layers was improved. The composite layers ensured a normal level of hemolysis during interaction with erythrocytes.

© 2019 by the authors. This paper reveals the mechanism of nanowelding a branched network of single-walled carbon nanotubes (SWCNTs) used as a framework for the formation of protein-polymer matrices with albumin, collagen, and chitosan. It is shown that the introduction of certain point defects into the structure of SWCNTs (single vacancy, double vacancy, Stone-Wales defect, and a mixed defect) allows us to obtain strong heating in defective regions as compared to ideal SWCNTs. The wavelengths at which absorption reaches 50% are determined. Non-uniform absorption of laser radiation along with inefficient heat removal in defective regions determines the formation of hot spots, in which nanowelding of SWCNTs is observed even at 0.36 nm between contacting surfaces. The regularities of formation of layered protein-polymer matrices and the features of their interaction with cell membrane are revealed. All studies are carried out in silico using high-precision quantum approaches.

© 2018 IEEE. Authors describe new effect of laser radiation in endoscopic urological surgery (BPH enucleation, en-bloc removal of bladder cancer, stricture endotomy): two-phase jet - a result of superintensive boiling in the area of laser radiation absorption and consisting of steam-gas microbubbles and hot water. In this case, the area of thermal influence appears significantly more, than thickness of a layer in which laser radiation is absorbed. Cutting soft tissue, the jet coagulates section walls due to heat generated at steam condensation. The same jet is formed behind the macrobubble, which is formed in liquid (Moses effect), because of boiling.

© 2018 SPIE. The conductivity of layers (thickness ∼ 0.5-20 μm) of composite nanomaterials consisting of bovine serum albumin (BSA) with single-walled carbon nanotubes (SWCNTs) has been studied. The BSA/SWCNT composite nanomaterial was prepared according to a route map, some steps of which are: the preparation of an aqueous dispersion based on BSA and SWCNT; preparation of substrates; deposition of BSA/SWCNT dispersion on substrates; application of water paste from SWCNT on substrates; irradiation of layers by lasers when they were in a liquid state; drying of samples; carrying out electrical and temperature measurements. Half of the layer was covered with a light-tight hollow box and the other half of the layer was laser irradiated. The laser irradiation of the layer was carried out for about 20 sec, at which time the layers completely became dry, while the other half of the layer remained in liquid. Conductivity was increased (70 ÷ 650) % by laser irradiation of the layers when they were in the liquid state. Maximum values of specific conductivity for BSA/SWCNT-1 S/m layers, and for layers SWCNT - 70 kS/m. The investigated electrically conductive layers of 99 wt.% BSA/0.3 wt.% SWCNT are promising for medical practice.