Corneal damage is a significant problem in modern ophthalmology, and the repair of this damage through the transplantation of collagen films has become an attractive and promising approach in regenerative ophthalmology. We have developed a method for creating collagen films using simple and accessible techniques that enhance the migration of corneal cells. Our research has focused on investigating the effects of variables such as the concentration of chloride anions in collagen solutions and pre-cooling on the properties of these films. Using turbidity measurements, we found that pre-incubation of collagen solutions at low temperatures promotes the formation of fibrillar structures. Atomic force microscopy confirmed these findings, revealing an increase in fibrillar collagen content on the surface of the films. The proposed conditions for film formation contribute to an increase in the rate of migration of corneal cells. These films represent a promising product for use in corneal regenerative medicine.

Collagen is one of the main components of the extracellular matrix, inherent in various types of tissues, in each of which it has a certain structure. It is widely used to prepare carriers (scaffolds) for culturing and transplanting various types of cells during the restoration of damaged tissues. In the body, the extracellular matrix mainly consists of microand nanopatterns that are isotropic or anisotropic. Thus, the corneal stroma of the eye is a tissue with a pronounced topographic structure. There are various physical approaches to creating a native stroma structure, such as: magnetic fields, mechanical alignment, structuring in an electric field, etc. The paper describes a technique for forming a structured tissue like structure based on collagen, with pronounced negative properties. The value of the isofocusing point for collagen genus in an external electric field is experimentally demonstrated, confirmed on the basis of calculation of the charge state of the collagen molecule, with visualization of the formation process using both polarization microscopy and by attaching a fluorescent label.

Gels based on type I collagen have been actively studied over the past decades and are already used in regenerative medicine. The main limitation of using gels is the impossibility of long-term cell cultivation inside the gels due to their contraction under the influence of cells. Gels have the greatest regenerative potential after a long time of cells cultivation, since the cells synthesize extracellular matrix proteins and growth factors. In the contracting gels, cells cannot expand, resulting in deterioration of the beneficial functional properties of the gel. To increase the rigidity of the gel, we used carboxymethyl cellulose (CMC). However, there are no data in the literature on the analysis of the interaction of cells with such scaffolds. We formed composite gels based on 2 % type I collagen and 5 % CMC, which are superior to gels based on pure collagen. Spectrophotometry, FTIR and SEM techniques confirmed the preservation of the native structure of collagen fibril in the presence of CMC, while the rigidity and stability of the composite gel increased noticeably compared to pure collagen gel. For the first time, studies were conducted to evaluate the direct interaction of human cells with composite gels based on collagen and CMC.

In the body, collagen is found in a specific structural arrangement that determines the basic functions of tissues. One of the main goals of tissue engineering is to replicate this arrangement in vitro to create structures that mimic natural tissues. In this study, we used 3D printing to create nanostructures of type I collagen. We found that the concentration of protein in the solution is a crucial factor in determining the ability of the collagen to form structures. When the concentration was 70 mg/mL, the resultant structures had parallel fibrils. Human skin fibroblasts grown on the surface of the structured collagen scaffolds aligned themselves along the fibrils. These engineered structures can be used for tissue engineering and regenerative medicine applications.

Extracellular matrix proteins have a complex assembly in tissue and it is believed that not only the chemical structure, but also their location, plays an important role in cellular functions. Collagen is one of the main components of the extracellular matrix and the oriented arrangement of collagen fibrils in tissues such as bone, cartilage, tendons, and cornea has a significant impact on various tissue functions. In the body, the orientation of extracellular matrix proteins is determined by cells. Oriented collagen fibrils can not only promote directed cell migration, but also stimulate cells to secrete an extracellular matrix with an oriented structure. However, the creation of collagen fibrils with an oriented structure in vitro is still associated with a number of limitations. Such limitations are primarily because the mechanisms regulating cellular functions in the orientation of extracellular matrix proteins, including collagen, are still unknown. Currently, only physical ways of organizing collagen fibrils in a certain direction are known. We hope that the description of the orientation of collagen fibrils in this review will allow readers to better understand the processes that occur with molecules. The study of methods and conditions for obtaining oriented collagen fibrils can help to obtain tissue biomimetic materials with complex properties identical to native tissues. Therefore, we discuss here various methods and conditions for obtaining oriented collagen fibrils in vitro using mechanical, electric, magnetic, and other fields. The prospects of application in tissue engineering and scientific problems of oriented collagen fibrils are also described.

Using high-temperature annealing of thin gold nanofilms deposited onto the (001) surface of doped p-GaAs crystal with an ultrathin oxide layer, the nanoclusters of gold (Au2Ga alloy) are fabricated. The gold clusters have the wedge shapes with rectangular bases elongated in [110] direction at GaAs(001) surface. This assertion is confirmed by the data of diagnostics of Au/p-GaAs(001) structures. Anisotropic plasmons localized on equally oriented wedge-shaped Au (Au2Ga) clusters are investigated with the optical reflectance anisotropy spectroscopy and spectroscopy of polarized light reflection. It is shown that the spectral peak at the energy about 0.9 eV in the near infrared range is associated with plasmons polarized along the longest sides of clusters in crystallographic direction [110]. Another peak—at the energy of 1.8 eV—is due to plasmons having polarization in direction [11̅0] .

Anisotropic wet etching of vicinal monocrystalline Si (111)4o wafers was used to obtain blazed gratings that are highly efficient in the soft X-ray (SXR) and extreme ultraviolet (EUV) applications. An improved experimental technology for the fabrication of triangular-grooved Si gratings, both medium-frequency (250 and 500 mm-1) and high-frequency (2500 mm-1) ones, is presented. The stages of forming a Cr-mask for grooves etching, removing Si nubs in order to smooth the profile, and polishing the surface to reduce nanoroughness have been optimized. This paper describes the way of simultaneously (in one process) obtaining a smoothed triangular profile of the Si grating and a polished surface of facets by wet etching. Keywords: diffraction grating, Si wet etching, triangular groove profile, AFM, SEM.

The umbilical cord is a material that enhances regeneration and is devoid of age-related changes in the extracellular matrix (ECM). The aim of this work was to develop a biodegradable scaffold from a decellularized human umbilical cord (UC-scaffold) to heal full-thickness wounds. Decellularization was performed with 0.05% sodium dodecyl sulfate solution. The UC-scaffold was studied using morphological analysis methods. The composition of the UC-scaffold was studied using immunoblotting and Fourier transform infrared spectroscopy. The adhesion and proliferation of mesenchymal stromal cells were investigated using the LIVE/DEAD assay. The local reaction was determined by subcutaneous implantation in mice (n = 60). A model of a full-thickness skin wound in mice (n = 64) was used to assess the biological activity of the UC-scaffold. The proposed decellularization method showed its effectiveness in the umbilical cord, as it removed cells and retained a porous structure, type I and type IV collagen, TGF-β3, VEGF, and fibronectin in the ECM. The biodegradation of the UC-scaffold in the presence of collagenase, its stability during incubation in hyaluronidase solution, and its ability to swell by 1617 ± 120% were demonstrated. Subcutaneous scaffold implantation in mice showed gradual resorption of the product in vivo without the formation of a dense connective tissue capsule. Epithelialization of the wound occurred completely in contrast to the controls. All of these data suggest a potential for the use of the UC-scaffold.

The paper presents a method of microwave influence on ferrocene C10H10Fe and graphite to obtain multilayer carbon nanotubes (MWCNTs) — designed to improve the electrical and thermophysical properties of silicon-graphite elastomer (Silagerm 8020). Diagnostics and characterisation of the synthesised MWCNTs were carried out by energy dispersive X-ray analysis (EDX), X-ray diffraction (XRD), scanning electron microscopy (SEM) and Raman spectroscopy. According to SEM data, it follows that the morphology of the synthesised MWCNTs has the form of filamentous formations intertwined in bundles with the diameter of individual MWCNTs from 40 to 60 nm and length up to several microns. At the same time, the surface of most of the MWCNTs is covered with a continuous layer of iron (Fe). The EDX method also confirmed the Fe and oxygen content on the surface of the MWCNTs. XRD method identified the presence of Fe in combination with carbon in the form of Fe3C iron carbide and pure Fe iron at 44.7°. The compound Fe3C, also referred to the active phase of Fe allowing the synthesis of MWCNTs. By increasing the concentration of MWCNTs in the elastomer, an increase in thermal conductivity with percolation transition was achieved at a concentration of 8 % MWCNTs. The maximum thermal conductivity of the nanomodified elastomer was 0.48 W/(m·°C), which corresponded to the mass concentration of MWCNTs equal to 8 wt.%. At the same time, the electrical conductivity of the composite, when the MWCNTs concentration was changed from 1 to 8 %, increased in the range from 4·10–5 to 2.4 cm·cm–1 and is also due to the percolation of MWCNTs in the elastomer matrix.

The results of investigations by the method of Electron beam-induced current of p-n-junctions based on InP with GaP crystallites in the space charge region are presented. It is shown that the introduction of crystallites into the space charge region leads to short-circuiting of the p-n-junction. The quality of the material grown on top of the crystallites allows to create of photoactive regions, as evidenced by measurements of the photoluminescence spectra. Keywords: crystallites, tunnel junction, connecting element.

Wedge-shaped nanoclusters of gold (Au2Ga) are fabricated by high-temperature annealing of a gold nanofilm deposited onto (001) surface of p-doped GaAs crystal with a very thin overlayer of natural oxide. The data of diagnostics confirm the presence in prepared Au/p-GaAs(001) structures of the wedge-shaped Au-intermetallic nanoclusters elongated in [110] direction at GaAs surface. A crystallographic model of the wedge-shaped Au (Au2Ga) nanoclusters conditioned by GaAs(001) surface is discussed in relation with their physicochemical nature. Anisotropic plasmons localized on equally oriented Au-based nanoclusters are detected optically with the reflectance anisotropy spectroscopy and investigated thoroughly with the spectroscopy of polarized light reflection. It is proved experimentally and theoretically that the inhomogeneously broadened infrared spectral peak at the energy about 1.1 eV is associated with plasmons polarized along the wedge-shaped clusters in [110] crystal direction. Another peak - at the energy approximately of 1.8 eV - is due to plasmons having orthogonal polarization in direction [110].

Herein, we report a single-step immobilization of hydroxyapatite (HAp) on the surface of poly(vinylidene fluoride) copolymer. This method utilizes the ability of fluoropolymer to undergo a limited swelling in acetone/ water mixture followed by an entrapment of HAp on its surface. We found that while acetone/water ratio does not affect the thickness of HAp-containing layer, an increase in acetone content results in higher amounts of calcium and phosphorus found in modified area. HAp immobilization not only improved the hydrophilicity of the poly(vinylidene fluoride) copolymer surface but also contributed to enhanced cell adhesion (0.8 +/- 0.4 % for the fluoropolymer surface vs. 86.9 +/- 9.1 % for the modified fluoropolymer surface) and viability (increased by up to 30 %). Overall, this method represents a potent strategy for the modification of fluoropolymers which allows for the fabrication of bioactive implants using standard laboratory equipment.

In this study, the morphology and crystallographic properties of thin titanium (Ti) films grown on atomically smooth gallium arsenide (GaAs) substrates are examined. The films were grown by direct current magnetron sputtering in an argon (Ar) flow. The surface is found to be atomically smooth with steps up to 0.1 nm in height and a morphology close to that of the Ti film substrate with nominal thicknesses of 5 and 10 nm. Increasing the film thickness to 60 nm leads to a noticeable surface reconstruction, associated with the formation of clusters up to 16 nm in height. As per X-ray diffraction studies, all films show a crystal structure of the alpha-Ti phase. In this case, an increase in the crystallite size from 7 to 20 nm and an increase in the film nominal thickness from 5 to 60 nm are also typical. Based on atomic force microscopy analysis, a change is observed in surface morphology. When the film thickness increases from 10 to 60 nm, clusters are formed on the Ti film surface, measuring 1 mu m in diameter and 16 nm in height.

The properties of lithium‐ion battery (LIB) anodes fabricated from nanoscale silicon Si and polyaniline (PANI) as a binder are reported. PANI is prepared by in situ polymerization of aniline in the presence of phytic acid, which serves both as dopant and as a gel‐forming agent. PANI pellets obtained by dry compression are used to investigate the morphology and to measure the resistivity of PANI and Si/PANI composites. The anodes are fabricated using the slurry technique. Their properties as a function of precursor ratio are studied in the half‐cell cells by charge–discharge characteristics, cyclic voltammetry, electrochemical impedance spectroscopy and cyclic lifetime. It is shown that stable cycling (>350 cycles at a current of 300 mA g−1) is inherent only to thin Si/PANI layers with composite loading <0.7 mg cm−2. The discharge capacity in this case is as high as 500–800 mAh g−1.

The work is devoted to a comparative study of the electrochemical behavior and molecular level transformations in TiF3 and TiOF2 electrodes of Li-ion batteries at charge-discharge processes. Based on analysis of the electrode voltage profiles, we propose possible redox reactions which occur with the change of Ti oxidizing state. According to these models, titanium trifluoride has a reversible capacity of 600 mAh/g, TiOF2 of 395 mAh/g. It has been shown that titanium oxyfluoride is characterized by a long cycle life while specific capacity of the titanium trifluoride rapidly degrades. The degradation of TiF3 is associated with a temporal molecular ordering and decrease in the chemical activity of titanium and lithium fluoride formed during the reversible introduction of lithium. The related effect lies under the superreversibility phenomenon in TiOF2 electrodes (Coulomb efficiency more than 100%). The dependences of the equilibrium voltage and chemical diffusion coefficient of Li on the concentration of Li were determined from GITT analysis.

Three-dimensional (3D) bioprinting opens up many possibilities for tissue engineering, thanks to its ability to create a three-dimensional environment for cells like an extracellular matrix. However, the use of natural polymers such as silk fibroin in 3D bioprinting faces obstacles such as having a limited printability due to the low viscosity of such solutions. This study addresses these gaps by developing highly viscous, stable, and biocompatible silk fibroin-based inks. The addition of 2% carboxymethyl cellulose sodium and 1% sodium alginate to an aqueous solution containing 2.5 to 5% silk fibroin significantly improves the printability, stability, and mechanical properties of the printed scaffolds. It has been demonstrated that the more silk fibroin there is in bioinks, the higher their printability. To stabilize silk fibroin scaffolds in an aqueous environment, the printed structures must be treated with methanol or ethanol, ensuring the transition from the silk fibroin’s amorphous phase to beta sheets. The developed bioinks that are based on silk fibroin, alginate, and carboxymethyl cellulose demonstrate an ease of printing and a high printing quality, and have a sufficiently good biocompatibility with respect to mesenchymal stromal cells. The printed scaffolds have satisfactory mechanical characteristics. The resulting 3D-printing bioink composition can be used to create tissue-like structures.

The results of experimental study of morphology of silver nanostructures, which appear during thermal destruction of polyvinyl alcohol film with silver nitrate are presented. It is shown that during the increase of silver nitrate concentration the maximum size of the formed particles increases from tens of nanometers up to 2 μm, and their shape transforms from spherical to irregular. The growth of silver nanoparticles occurs at the expense of small silver nanoparticles migration on a substrate surface, their gathering near the large nanoparticles and confluence of small nanoparticles with larger ones. Keywords: nanoparticle, silver, polyvinyl alcohol, morphology, absorption, luminescence .

The properties of graphene chips with low reproducibility (LR) after photolithography (PLG) and graphene functionalization have been studied. It is shown that the introduction of additional cleaning after PLG can significantly increase the reproducibility of the parameters of processed graphene in biosensors. The use of dilute PBS solutions for virus detection makes it possible to increase the relative concentration sensitivity of biosensors by several times.

Cellulose is one of the main renewable polymers whose properties are very attractive in many fields, including biomedical applications. The modification of nanocrystalline cellulose (NCC) opens up the possibility of creating nanomaterials with properties of interest as well as combining them with other biomedical polymers. In this work, we proposed the covalent modification of NCC with amphiphilic polyanions such as modified heparin (Hep) and poly(αL-glutamic acid) (PGlu). The modification of NCC should overcome two drawbacks in the production of composite materials based on poly(ε-caprolactone) (PCL), namely, (1) to improve the distribution of modified NCC in the PCL matrix, and (2) to provide the composite material with osteoconductive properties. The obtained specimens of modified NCC were characterized by Fourier-transform infrared spectroscopy and solid-state 13C nuclear magnetic resonance spectroscopy, dynamic and electrophoretic light scattering, as well as thermogravimetric analysis. The morphology of PCL-based composites containing neat or modified NCC as filler was studied by optical and scanning electron microscopy. The mechanical properties of the obtained composites were examined in tensile tests. The homogeneity of filler distribution as well as the mechanical properties of the composites depended on the method of NCC modification and the amount of attached polyanion. In vitro biological evaluation showed improved adhesion of human fetal mesenchymal stem cells (FetMSCs) and human osteoblast-like cells (MG-63 osteosarcoma cell line) to PCL-based composites filled with NCC bearing Hep or PGlu derivatives compared to pure PCL. Furthermore, these composites demonstrated the osteoconductive properties in the experiment on the osteogenic differentiation of FetMSCs.