Utilizing reactive DC magnetron sputtering method, TiN coatings were deposited on the silicon substrates at different nitrogen flows and powers. A study of the X-ray phase composition of the coatings was carried out. The stoichiometric composition of the coatings was determined using energy dispersive x-ray spectroscopy. The structure of the surface, cross-section, and thickness of the coatings were determined using scanning electron (SEM) and atomic force microscopy (AFM). A significant change in the surface structure of TiN coatings was established with changes in deposition power and nitrogen flow. SEM images of cross-sections of all coated samples showed that the formation of coatings occurs in the form of a columnar structure with a perpendicular orientation relative to the silicon substrate. The mechanical properties (elastic modulus E and microhardness H) of TiN coatings of the first group demonstrate a maximum at a nitrogen flow of 3 sccm and are 184 ± 11 GPa and 15.7 ± 1.3 GPa, respectively. In the second group, the values of E and H increase due to a decrease in the size of the structural elements of the coating (grains and crystallites). In the third group, E and H decrease. Microtribological tests were carried out in 4 stages: at a constant load, multi-cycle for 10 and 100 cycles, and with increasing load. The coefficient of friction (CoF) and specific volumetric wear ω depend on the roughness, topology, and mechanical properties of the resulting coatings. Fracture toughness was determined using nanoscratch and depends on the mechanical properties of TiN coatings. Within each group, coatings with the best mechanical and microtribological properties were described: in the first group—TiN coating at 3 sccm (with (29.6 ± 0.1) at.% N), in the second group—TiN coating at 2 sccm (with (40.8 ± 0.2) at.% N), and in the third group—TiN coating at 1 sccm (c (37.3 ± 0.2) at.% N).

Collagen is a major extracellular-matrix protein widely used in regenerative medicine, yet conventional terrestrial sources raise biosafety and acceptability concerns, motivating the search for marine alternatives. This study evaluates the jellyfish Rhizostoma pulmo (R. pulmo) from the Azov Sea as a sustainable collagen source and assesses its suitability for biomedical materials. Acid-soluble collagen was extracted using 0.5 M acetic acid and purified by salt precipitation and dialysis, followed by physicochemical/structural characterization (sodium dodecyl sulfate–polyacrylamide gel electrophoresis (SDS–PAGE), Limulus amebocyte lysate (LAL) endotoxin testing, transmission electron microscopy (TEM), and immunofluorescence with type I collagen antibodies) and biological evaluation in vitro (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) cytotoxicity on MRC5 fibroblasts; adhesion and proliferation assays on HeLa cells). The extracted collagen showed a high yield (~26.2%), a type I-like electrophoretic profile with α-, β-, and γ-components, fibrillar ultrastructure by TEM, and positive type I collagen immunoreactivity; endotoxin levels were low (0.461 EU/µL), and no cytotoxicity was detected under the tested conditions. Porous collagen sponges/scaffolds were fabricated by lyophilization, displaying interconnected pores with an average size of ~80 µm and pH-dependent swelling, and they supported 3D cell growth and tumor-cell dissemination in an in vitro breast carcinoma scaffold model. Overall, Azov Sea R. pulmo collagen demonstrates promising structural quality, low endotoxin burden, and cytocompatibility, supporting its potential as a marine biomaterial for sponge/scaffold-based tissue engineering and wound-related applications.

The present paper presents the results of a comprehensive study of the adhesion force between the tip of an atomic force microscope probe and the hard tissues of a human tooth, both in normal physiological conditions and in the presence of pathological changes, including carious lesions and localized demineralization at the fissure apex. The use of force spectroscopy allowed us to obtain quantitative data reflecting differences in the adhesion properties of enamel and dentine due to changes in their structure, degree of mineralization and surface topography. Combined imaging techniques – atomic force and optical microscopy – were used to assess the microstructural features of dental tissue. It was found that pathologically altered areas are characterized by deviations in adhesion force compared to sound tissue. The obtained data highlight the high sensitivity of atomic force microscopy to subtle structural and functional changes in biological tissues and demonstrate its potential as a tool for comprehensive nanomechanical characterization of dental hard tissues. The study's preliminary results can be used both in fundamental biomechanical and biomedical research – in particular, for the parameterization and verification of finite element and multiphysics mathematical models – and in applied areas: for developing new diagnostic approaches in dentistry, evaluating the effectiveness of preventative measures (e.g., remineralizing compounds), and optimizing the properties of restorative materials.

Metal-coated polymer electrodes fabricated by additive manufacturing are promising tools for electrical discharge machining (EDM) of complex shapes; however, coating non-uniformity and thermomechanical degradation limit their performance. This study presents experimental and theoretical results for a hybrid tool electrode fabricated by stereolithography (SLA), followed by electroless and electrochemical copper plating, and used to machine St3 structural steel. Optical and scanning electron microscopy, energy-dispersive spectroscopy (EDS), atomic force microscopy, X-ray microtomography, Raman spectroscopy, simultaneous thermal analysis and nanoindentation were used to characterize the coating before and after EDM. The electroplated copper layer exhibited pronounced thickness non-uniformity (264–1225 µm), an edge effect and dendritic morphology associated with the primary current distribution and the absence of leveling additives. Surface modification during EDM was accompanied by changes in the elemental composition measured by EDS. After EDM, the Fe and C signals reached 23.32 wt.% and 35.56 wt.%, respectively, under the acquisition and quantification conditions used. These values characterize local surface composition and do not establish bulk incorporation of iron or carbon into the copper layer. No pronounced bulk thermal degradation was detected in the examined photopolymer specimens; exposure of the polymer base nevertheless promotes local damage. A coupled numerical model combines a boundary element calculation of copper deposition, normal coating recession and cavity formation; a single-discharge thermal solver provides diagnostic calculations. The model describes the principal copper-wear and cavity development trends for the investigated electrode, including the end face and chamfer and reproduction of coating and printing defects. Because only one electrode was fabricated, plated and tested, the work is presented as a detailed case study. The observed variability reflects within-specimen measurement scatter and spatial heterogeneity rather than reproducibility between independently manufactured electrodes. The results demonstrate the feasibility of SLA-printed copper-plated electrodes for EDM and identify coating uniformity, adhesion and thermal damage as factors affecting dimensional stability and service life. A solid copper control was not tested under identical conditions, so no direct experimental comparison of machining performance or wear resistance is presented. Seven residual thicknesses determine the deposition parameters, and three working-surface thicknesses determine two effective EDM parameters; all ten locations are calibration data. The mean absolute relative discrepancy is 1.47% for the working locations and 4.42% for all locations. These are fitting metrics. The calculated cavity depth of approximately 8.4 mm and steel removal rate of approximately 35 mm³/min have not been independently measured. Numerical verification and sensitivity analysis are distinguished from independent experimental validation.