Yuriy Halyafovich Akhmadeev

Traditional methods of treating open wounds are not always effective, as they require frequent and traumatic dressing changes, as well as the use of various medications, which can negatively affect the body. Current research is focused on developing new wound coverings that promote faster and more effective recovery of damaged tissues. The development of new fibrous materials based on polylactic acid and the diterpene alkaloid songorine, isolated from the above-ground part of the Aconitum barbatum plant, is proposed in this work. These materials are designed to serve as targeted delivery systems for effective healing of damaged skin surfaces. Scaffolds based on the aliphatic polymer were prepared by electrospinning. Two-stage (combined) surface treatment of the samples was carried out by low-temperature plasma treatment in a nitrogen flow for 5 min, followed by surface adsorption of songorine in the amount of 5 wt % onto the plasma-modified surface of the materials. The method of combined modification leads to the formation of nitrogen- and oxygen-containing bonds on the surface of polymer materials, as determined by X-ray photoelectron spectroscopy, which results in improved physicochemical and biological properties. Macrophage viability studies showed that all scaffolds were biocompatible: the number of living cells corresponded to the control level. Scanning electron microscopy revealed that surface treatment does not affect the morphology of the scaffold surface. It was found that songorine accelerates the degradation of the materials. Using UV detection, it was shown that the release of songorine from the surface of the samples follows a “burst release” type of release characteristic of antibacterial coated systems.

The effect of surface modification by an arc discharge plasma in a nitrogen flow with treatment durations of 5 and 10 min on the physicochemical properties and biocompatibility of the surface of composites based on polylactic acid and hydroxyapatite (PLA/HA) with different mass ratios (80/20, 70/30, 60/40) has been investigated. The aim of this work was to show the correlation between the changes of the physicochemical characteristics (chemical compound, morphology, wettability) of the surface layer of the PLA/HA composites and the cell viability (macrophages) in the presence of the plasma-modified materials. The dependence of alterations of the functional properties (wettability, biocompatibility) on the change in the chemical composition under the plasma exposure has been established. The chemical composition was studied using X-ray photoelectron spectroscopy (XPS), the surface morphology was researched with scanning electron microscopy (SEM), and the wettability of the composite’s surface was analyzed by measuring the contact angle and surface energy calculation. In addition, the viability of macrophages was investigated when the macrophages from three donors interacted with a modified PLA/HA surface. It was found that the formation of the new functional groups, –C-N and N-C=O/C=O, improves the wettability of the surface of the composites and promotes the viability of macrophages in the presence of the composite materials. The fundamental principles for obtaining promising materials with the required properties for eliminating bone defects have been created.

A developed vacuum-arc plasma-assisted method is applied to produce films of a high-entropy alloy from a multicomponent gas-metal plasma generated by the simultaneous independent evaporation of selected metal cathodes. New modes are revealed to allow the deposition of thin films of a high-entropy alloy, AlTiCrNbMo–N, with a nearly equiatom composition. The films are a multilayer nanocrystalline material with a body-centered cubic lattice, the parameter of which specifically depends on the concentration of elements in the alloy. The synchrotron-radiation technique demonstrates that films of the high-entropy alloy AlTiCrNbMo–N are stable when heated in air to temperatures not exceeding 620°C.

We consider some new and recently modernized vacuum ion-plasma electrophysical facilities used to create dense low-temperature plasma in considerable volumes (≥0.25 m³), as well as a complex unit that includes beam and plasma modules for various processes of electron-ion-plasma modification of the surface of materials and products to improve their functional properties. The paper also provides the examples of modification processes using the developed equipment, as well as the results on improving the properties of modified surfaces.

The effect of low-temperature arc discharge plasma treatment in a nitrogen atmosphere on the modification of the physicochemical properties of PLA-based scaffolds was studied. In addition, the cellular-mediated immune response when macrophages of three donors interact with the modified surfaces of PLA-based scaffolds was investigated. PLA surface carbonization, accompanied by a carbon atomic concentration increase, was revealed to occur because of plasma treatment. Nitrogen plasma significantly influenced the PLA wettability characteristics, namely, the hydrophilicity and lipophilicity were improved, as well as the surface energy being raised. The viability of cells in the presence of the plasma-modified PLA scaffolds was evaluated to be higher than that of the initial cells.

Multilayer cermet coatings based on a TiNbZrTaHf high-entropy alloy were produced on solid substrates by plasma-assisted vacuum-arc deposition. The assisting multicomponent metal-gas plasma was generated by evaporating TiNbZrTaHf cathodes in a gas mixture of nitrogen and argon. It was found that the coatings were nanocrystalline in structure (with nanocrystal sizes ranging from 2.5 to 4 nm). The metallic layer had a body-centered cubic lattice (a = 0.33396 nm), and the ceramic layer had a face-centered cubic lattice (a = 0.44465 nm). Transition layers formed between the substrate and the metallic layer and between the metallic and the ceramic layers were revealed. The hardness of the coatings was 36.7 GPa and their Young’s modulus was 323 GPa.

The paper analyzes the structure and properties of metal, cermet, and ceramic NbMoCrTiAl high-entropy alloy (HEA) coatings formed on solid substrates by plasma-assisted vacuum arc deposition (from multicomponent gas-metal plasma through Nb, Mo, Cr, and TiAl cathode evaporation in argon and/or a mixture of argon and nitrogen). The analysis shows that all coatings represent a nanocrystalline (3–5 nm) multilayer film. The metal coating has a bcc lattice (a = 0.3146 nm). The ceramic coating has an fcc lattice (an uncertain lattice parameter due to highly smeared diffraction peaks). The coating hardness increases in the order of metal, cermet, and then ceramic, reaching 43 GPa at Young’s modulus equal to 326 GPa. When heated in air, the metal and cermet coatings start to oxidize at 630–640 °C, and the ceramic coating at 770–780 °C.