The effect of ultrashort laser radiation parameters on the process of biomaterial formation based on dispersed media of bovine serum albumin and carbon nanotubes was studied. It is noted that, in contrast to the use of continuous laser radiation of comparable power, the composite nanomaterial is formed when lower temperatures are reached, which provides additional advantages and a smaller change in the protein structure. This effect can also be associated with a pulse repetition rate of 80 MHz, in the interval, which is about 12.5 ns, partial cooling of the material can occur, while this effect is sufficient for the formation of a biomaterial. The hardness of this material is comparable to that of native tissue. A strong twofold change in the elasticity of such a material in comparison with drying in air indicates the formation of an inner framework of carbon nanotubes. The possibility of this effect is also confirmed by spectral studies, according to which, at the used wavelength of 810 nm, the radiation is absorbed mainly by carbon nanotubes and only as a result of heat transfer is transmitted to bovine serum albumin and is spent on water evaporation. In vitro studies of cell growth in the presence of biomaterial were carried out by quantitative (MTT test) and qualitative (microscopy) methods. It was found that the number of cells grown on the composites exceeds the number of cells in the control after 72 hours of incubation. The cells on the composites formed a monolayer, their morphology does not differ from the morphology of the cells in the control. In vitro studies indicate a positive effect of the biomaterial on cell adhesion and proliferation and, consequently, on the possibility of their use for tissue regeneration.
The paper represents a study on the characteristics and biocompatibility of tissue-engineering structures with nanocarbon scaffolds in the bioorganic matter for various bioengineering applications, including biomedical devices for the heart treatment and neurostimulation. These structures were obtained via a laser formation method. Structures were printed using previously developed laser setup and had a cellular structure in accordance to the cell monolayer formation. It was established that SWCNT bind to amino acids through oxygen atoms. It was observed that the SWCNT diameter increased due to their wrapping by a bioorganic matter. Moreover, electrical conductivity values of such structures exceeded the heart tissue conductivity (0.1 S/m) and reached 8.5 S/m. The proliferation of fibroblasts and endothelial cells on the studied structures was demonstrated via the fluorescence microscopy and the MTT assay. The density of proliferated cells on structures was higher than in control samples. Finally, the biodegradation rate of tissue-engineered structures during the implantation to laboratory animals was 75-90 days, the samples promoted neovascularization of the affected tissue.
The technology of cell 3D scaffolds laser fabrication is developed. 3D scaffolds are designed to repair osteochondral defects, which are poorly restored during the organism’s life. The technology involves the use of an installation, the laser beam of which moves along a liquid nanomaterial and evaporates it layer by layer. Liquid nanomaterial consists of the water-protein (collagen, albumin) suspension with carbon nanoparticles (single-walled carbon nanotubes). During laser irradiation, the temperature in the region of nanotubes defects increases and nanotubes are combined into the scaffold. The main component of installation is a continuous laser operating at wavelengh of 810 nm. The laser beam moves along 3 coordinates, which makes it possible to obtain samples of the required geometric shape. The internal and surface structure of the samples at the micro- and nanoscale levels were studied using the X-ray microtomography and scanning electron microscopy. In vitro studies of cell growth during 48 and 72 hours demonstrated the ability of cell 3D scaffolds to support the proliferation of osteoblasts and chondroblasts. Using fluorescence and atomic force microscopy, it was found that the growth and development of cells on a sample with a larger concentration of nanotubes occurred faster compared to samples with a smaller concentration of nanotubes.
Creation of limiters for intensive laser radiation requires the development of effective methods for testing materials to determine the nonlinear optical parameters characterizing their properties. The limiting threshold, linear and nonlinear absorption coefficients can be determined not only from data of Z-scan with open aperture, but also with the help of a fixed location of the limiter. The use of this method makes it possible to determine the output characteristic of the studied material from which nonlinear optical parameters can be calculated. Characteristics of carbon nanotubes and graphene oxide in water were obtained with the fixed location of the limiter. The experiments were performed using an Nd:YAG laser that generates pulses of 16 ns duration at a wavelength of 532 nm with the linearly polarized laser beam in the horizontal plane and a shape closed to Gaussian type. Theoretical curves for method of fixed location of the sample according to threshold model was calculated and compared with the experimental data. Normalized weakening coefficients, limiting threshold, linear and nonlinear absorption coefficients were found for studied dispersions and calculation of Z-scan with open aperture was made. The value of normalized weakening coefficient was higher in dispersed medium of SWСNTs with water (Knorm≈20) in comparison with oxide graphene in water (Knorm≈14). The dependences of normalized weakening coefficient bias input energy were approximately linear in both cases.
The study of structural properties of nanocomposites, based on different types of single walled carbon nanotubes (SWCNTs) and proteins (albumin, collagen), was carried out. The binding of protein molecules to the carbon component was described by Raman spectroscopy. Complex analysis of the structure and microporosity of nanocomposites was performed by the X-ray microtomography. The nanoporosity study was carried out using the low-temperature nitrogen porosimetry method. Samples based on SWCNTs with smaller size had the most homogeneity. With an increase in the concentration from 0.01 to 0.1 %, the mean micropore size increased from 45 to 93 μm, porosity in general increased from 16 to 28 %. The percentage of open pores was the same for all samples and was 0.02. As it was shown by Raman spectroscopy the protein component in nanocomposites has undergone irreversible denaturation and can act as a biocompatible binder and serve as a source of amino acids for biological tissues. These nanocomposites are bioresorbable and can be used to repair cartilage and bone tissue. This is especially important in the treatment of diseases of hyaline cartilage and subchondral bone.
Samples of liquid dispersions of gold nanorods and nanostars with different size and shape were synthesized and studied based on dynamic light scattering, polarization measurements, electrophoretic light scattering.
A new method for the formation of composite nanomaterials based on multi-walled and single-walled carbon nanotubes (CNT) on a silicon substrate has been developed. Formation is carried out by ultrasound coating of a silicon substrate by homogenous dispersion of CNTs in the albumin matrix and further irradiation with the continuous laser beam with a wavelength of 810 nm and power of 5.5 watts. The high electrical conductivity of CNTs provides its structuring under the influence of the laser radiation electric field. The result is a scaffold that provides high mechanical strength of nanocomposite material (250 MPa). For in vitro studies of materials biocompatibility a method of cell growth microscopic analysis was developed. Human embryonic fibroblasts (EPP) were used as biological cells. Investigation of the interaction between nanocomposite material and cells was carried out by optical and atomic force microscopy depending on the time of cells incubation. The study showed that after 3 hours incubation EPP were fixed on the substrate surface, avoiding the surface of the composite material. However, after 24 hours of incubation EPP fix on the sample surface and then begin to grow and divide. After 72 hours of incubation, the cells completely fill the sample surface of nanocomposite material. Thus, a nanocomposite material based on CNTs in albumin matrix does not inhibit cell growth on its surface, and favours their growth. The nanocomposite material can be used for creating soft tissue implants
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