Natural and synthetic polymers play a central role in the development of biomedical devices and tissue-engineering constructs. They are used either as standalone materials or as components of composite systems incorporating cells and bioactive substances. Because no single material can satisfy all requirements of a biomedical application, composite systems that combine complementary properties of their constituent components are of particular scientific and practical interest. Among natural polymers, silk proteins—silk fibroin and silk sericin—stand out as evolutionarily refined, functionally complementary components of a natural composite. To date, an extensive body of research devoted to both individual silk proteins and composite materials based on them in combination with other biological agents or auxiliary substances of inorganic and organic origin has been published. At the same time, relatively limited attention has been paid to materials based exclusively on the interactions between silk proteins themselves—“silk fibroin/silk sericin” or “silk fibroin/silk fibroin” composites—in various physicochemical forms. This review critically evaluates current strategies for designing silk-protein-based materials and discusses their potential biomedical applications.
The possibility of integration/immobilization of biogenic Ag–Se, Ag–Cd–S and Ag2S, CdS nanoparticles with antimicrobial action has been investigated into polymer nonwoven materials based on polyamide-6, polyacrylonitrile, polylactide, and polystyrene. Nanoparticles have been obtained by microbial synthesis using bacteria Shewanella oneidensis MR-1 and salts-sources of metal ions, selenium and sulfur. Nonwoven materials are characterized by size, fiber structure, and surface properties. It has been established that polyamide-6 and polyacrylonitrile are hydrophilic, while polylactide and polystyrene are highly hydrophobic. For all types of nanoparticles, the ability to immobilize throughout the entire volume of polyamide-6 and polyacrylonitrile has been demonstrated, while in the case of using polylactide and polystyrene, the fixation of nanoparticles occurs only in the upper layer of fibers. The surface properties of polymer nanocomposites do not undergo changes during the process of impregnation with biogenic nanoparticles. High antimicrobial activity has been established for polyamide-6 and polyacrylonitrile containing all types of nanoparticles, whereas for nanocomposites based on polylactide and polystyrene, the level of biocidal action was reduced.
A technologically simple method for forming highly porous composite particles of poly(3,4-ethylenedioxythiophene) polystyrene sulfonate with polyethylene glycol by spraying the dispersion followed by crystallization and sublimation of the solvent is proposed. The resulting particles have a predominantly spherical shape and are used as a filler for an electrorheological fluid based on silicone oil. The fluid exhibits solid-like behavior under an electric field, which is expressed in the appearance and increase of the static yield stress values. The mechanism of the electrorheological effect is analyzed based on the dependence of the static yield stress values on the electric field strength. The relative efficiency of the developed fluid has been assessed. A contrasting change in the behavior of the material during stimulation has been revealed. The ability of the fluid to repeatedly and sequentially respond to the electric field has been demonstrated.
The paper presents generalized data on the characteristics and functions of proteins associated with plant pathogenesis (Pathogenesis-Related Proteins, PR proteins). The content of these proteins can change under both biotic and abiotic stress. Nanoparticles, especially metal-containing ones, are capable of inducing the expression of genes encoding PR proteins, which helps plants successfully cope with stress. It has been established that under the influence of nanoparticles, mechanisms of systemic acquired resistance are activated in plants, and, as a rule, the level of gene transcripts PR1 increases.
The GSi025 process route developed at the National Research Centre “Kurchatov Institute” for fabricating microwave monolithic integrated circuits based on gallium nitride high-electron-mobility transistors on 100-mm silicon wafers with a 0.25 µm design rule is presented. The route includes combined lithography, a source field plate, multilevel metallization, a system for parametric and wafer acceptance control, and an “early” microwave transistor in the technology monitor. Fabrication of a reference wafer has demonstrated compliance of the dc, microwave, and passive-element parameters with the specified acceptance windows. A process design kit and a broadband amplifier have been used for auxiliary verification of the route applicability to the microwave monolithic integrated circuit design.
