Abstract: High-performance thermoplastics are lightweight and possess excellent mechanical properties over a wide temperature range. Composites of these materials and carbon nanotubes are expected to enhance mechanical performance while providing thermal and electrical conductivity. Polyether ether ketone (PEEK) is a lightweight, bioinert, high-performance thermoplastic with a wide range of applications in different fields, such as aerospace and biomedical devices. Sulfonated polyether ether ketone (SPEEK), which is obtained through sulfonation of PEEK, is a promising material for replacing traditional perfluorosulfonic acid membranes due to its excellent thermal stability, mechanical properties, and proton conductivity. Owing to their superior physical properties, carbon nanotubes (CNTs) can be introduced into PEEK and SPEEK matrices in order to further improve their conformances, opening up new perspectives for the development of the next generation of high-performance multifunctional materials.

Functionalization of CNTs provides a good approach to developing superior composite materials with enhanced mechanical properties. This process may enable interactions between the polymer matrix and CNTs to be controlled by using different functional groups attached to the nanotubes.

In this study, we present the covalent functionalization of pristine multi-walled carbon nanotubes (P-MWNTs) with poly(ether ether ketone) (SPEEK) chains, employing hexane diamine as an interlinking molecule. Both pristine and functionalized MWNTs (F-MWNTs) were then used to create PEEK/CNT and SPEEK/CNT composites. We used FTIR and NMR spectroscopy to confirm the covalent attachment of the SPEEK chains to the MWNTs and SEM and TEM to characterize the morphology of the functionalized tubes and composites. We evaluated the composites in terms of their structure, mechanical properties, and fracture morphology.

Our results show that SPEEK/F-MWNT composites with 2% F-MWNTs by weight exhibited a 7.1% improvement in their tensile modulus compared to SPEEK/MWNTs. However, the tensile modulus of PEEK/F-MWNTs increased by only 1.2%, while their tensile elongation decreased drastically.

Nowadays, the number of publications containing the keyword "hydroxyapatite" for the 2024-2025 period is more than 10,000 (according to ScienceDirect) due to the extensive use of this material. Hydroxyapatite is the main component in the framework for effective bone tissue regeneration because of its high biocompatibility and unique microstructure. Partial cationic substitution with rare earth elements (REEs) improves the characteristics of the original material and stimulates osteogenesis processes.

In this work, synthesis of Sm³⁺-, Pr³⁺-, and Gd³⁺-doped HA (with 6%/9% REEs) was performed. The solid phase was obtained through precipitation from aqueous solutions of calcium and REE nitrates, (NH₄)₂HPO₄. The powders were synthesized at a temperature of 70°C and a constant pH=11; dried at 100 °C; and calcined at 800 °C for 1 hour. The obtained materials were analyzed using IR–Fourier spectroscopy and XRD. The surface morphology and elemental composition were studied using SEM and EDS. The specific surface area indices were obtained using the BET method. The degradation of the materials in isotonic and tris-buffer solutions was also studied.

As a result of the investigation of the physicochemical properties, the materials were identified as a pure HA phase. They were nanosized particles connected in aggregates with many interaggregate pores. The IR spectra of the samples revealed bands of vibrations of carbonate and phosphate groups and vibrations of water in the structure. According to EDX, a decrease in the characteristic Ca/P ratio was noted, which confirmed cationic substitution in the Ca²⁺ positions.

Consequently, nanocrystalline hydroxyapatite doped with REE ions was synthesized through precipitation from aqueous solutions. It was found that the introduction of Pr³⁺, Sm³⁺, and Gd³⁺ affected the morphology and size of the particles. This system can be considered as a prospective biomaterial.

Introduction. Perovskite LaFeO₃ is a promising material due to its mixed ionic and electronic conductivity. The classic method for obtaining LaFeO₃ is the solid-phase reaction method, which includes several long cycles of ball milling and high-temperature sintering at 1400 °C. This paper presents the synthesis of LaFeO₃ nanoparticles using lanthanum and iron nitrates at 1200 °C, as well as the structural and photocatalytic properties of the obtained nanoparticles.

Materials and Methods. Perovskite LaFeO₃ nanoparticles were obtained by evaporating an aqueous solution of a mixture of La(NO₃)₃ and Fe(NO₃)₃, followed by annealing for 7 hours at 1200 °C. LaFeO₃ nanoparticles were studied by X-ray diffraction, SEM, EDX, UV-Vis diffuse light scattering, photoluminescence, and FTIR spectroscopy. The photocatalytic activity of LaFeO₃ nanoparticles was evaluated by the photocatalytic degradation of rhodamine B (RhB) solution; active radicals generated during photocatalytic reactions were determined by the "trapping" method.

Results. Nanoparticles of orthorhombic perovskite LaFeO₃ with an average crystallite size of approximately 63 nm were obtained; the band gap of LaFeO₃ nanoparticles was 3.21 eV. According to photoluminescence spectroscopy, LaFeO₃ nanoparticles exhibit low photoluminescence intensity, which indicates a low charge recombination rate. LaFeO₃ nanoparticles exhibit high photocatalytic activity in the UV range (350 nm). At a nanoparticle concentration of 40 mg per 50 ml of RhB solution (10 mg/l), the solution becomes discolored within 90 minutes; the active particles are OH-radicals.

Conclusion. It has been demonstrated that photocatalytically active LaFeO₃ nanoparticles with a size of t approximately 63 nm can be obtained using the nitrate method in one stage within 7 hours at a synthesis temperature of 1200°C. The LaFeO3 nanoparticles obtained using this method have high photocatalytic activity due to the generation of OH radicals upon irradiation with light of a wavelength of 350 nm.

The study was funded by the Russian Science Foundation (25-19-00458-P)

Composites based on Ce or Zr oxides (MeO₂) are highly demanded materials for energy, electronics, catalysis, and nanophotonics, but their development is hampered by high energy costs, difficulties in synthesis, and the lack of sound pressing and sintering modes for nanostructured powders. In this study, a method for producing composite powders based on oxygen-free graphene and MeO₂ for ceramics with a wide range of applications is proposed. The method is a combination of sol–gel and sonochemical techniques, allowing for the synthesis of hybrid structures with a uniform distribution of components in volume at the nanolevel. The developed hybrid structures consist of ceria or zirconia crystallites with dimensions of 6-14 nm, incorporated into graphene sheets several nm thick. Theoretically substantiated mechanisms for the formation of graphene suspensions, graphene–MeO₂ composites, and sintering of nanostructured hybrid powders are proposed based on the obtained experimental data. The positive effect of graphene on the microstructure of ceramics was determined: the use of a hybrid graphene–ZrO₂ powder makes it possible to obtain dense (98%), fine-grained ceramics with high structural homogeneity using the SPS method. It was shown that oxygen-free graphene on the surface of MeO₂ crystallites promotes the acceleration of surface exchange processes involving oxygen, which makes the developed composites promising raw materials for new electrical devices and catalysts. It was determined that graphene sheets and the method of their inclusion in the hybrid structure affect the activation energy of sintering and the mass transfer mechanism. The results of this study can be used as a basis for a technological process covering all stages, from obtaining initial solutions and colloids to sintered ceramics.

The relevance of this work lies in its contribution to water purification through two approaches. On the one hand, using sorbents made from foamed nanographite-structured materials, and on the other,employing eco-safe nanocomposites of carbon nitride with titanium dioxide, which is widely applied as a photocatalyst for water treatment via an advanced method: the generation of reactive oxygen species (ROS).

In the first stage of this work, the hypothesis posited that the earlier TiO₂ engages with and simultaneously synthesizes C₃N₄ during its formation , the more effective the resultant photocatalyst will be.

The first stage of this work included several steps:

1. SiO₂∙xEtOH and HₓTiᵧO₂∙H₂SO₄ sols were prepared and converted into gels: SiO₂∙8.6H₂O and TiO₂∙25.9H₂O (TGA).
2. Annealing in an inert atmosphere (3 h at 500°C; 3°C/min) was performed for melamine and its mixtures with desulfated titanyl sols: SiO₂‧8.6H₂O; TiO₂‧25.9H₂O and nano-TiO₂ P25. TGA modeling demonstrated that mass loss in the presence of TiO₂ was lower than with SiO₂.
3. AFM data revealed that the smallest particle size was observed in the thermolysis products of melamine mixtures either with the sol derived from (NH₄)₂TiO(SO₄)₂ (STA) or with the TiO₂‧25.9H₂O gel.
4. From the mixture of melamine with the STA-derived sol, semi-amorphous nanocrystalline g-C₃N₄ and rutile were formed (XRD). The mixture with the TiO₂‧25.9H₂O gel yielded the same phases, plus anatase.
5. The most effective photocatalyst for methyl orange degradation was C₃N₄ with TiO₂ from the STA-derived sol.

If, under the same temperature program, foamed melamine is subjected to thermolysis, a foamed product reproducibly crystallizes, which, according to XRD, is single-phase nanographite. The nanostructured layered morphology is confirmed by SEM. At the same time, according to CHNS analysis, this product contains carbon and 44% nitrogen. As a sorbent, this material absorbs 11 g/g of gasoline.

Introduction: Researching ways to regulate the biocorrosion rate of biodegradable magnesium implants is one of the most urgent tasks in the field of biomedical materials science. The most important objective is to maintain the corrosion resistance of the material during the initial stages after implantation, when this resistance subsequently decreases. Nanocoatings are the most effective means of achieving this. The present study investigates the potential of oxide nanocoatings to reduce the biocorrosion rate of AZ31 magnesium alloy in physiological Ringer's solution.

Methods: Atomic layer deposition (ALD) was used to create defect-free, uniform coatings based on titanium, aluminium and zinc oxides on AZ31 magnesium alloy surfaces. The thickness, composition, morphology, and structure of the coatings were analysed using ellipsometry, scanning electron microscopy, X-ray photoelectron microscopy, and X-ray diffraction. The biocorrosion rate was assessed by measuring potentiodynamic polarization curves and the mass loss of the samples.

Results: Al₂O₃ nanocoatings with a thickness ranging from 20 to 80 nm, as well as composite Al₂O₃-TiO₂ nanocoatings, are effective in reducing the rate of biocorrosion in AZ31 alloy. Conversely, TiO₂ coatings demonstrate reduced effectiveness and, in some cases, have been observed to slightly accelerate biocorrosion. The effectiveness of TiO₂ coatings was found to depend significantly on the precursor used: titanium tetrachloride or tetraisopropoxide. AZ31 biocorrosion rates were reduced by 18-54 times with Al₂O₃ and 40 nm thick Al₂O₃-TiO₂ composite coatings.

Conclusions: Among the ALD aluminium, zinc, titanium oxides and their composite nanocoatings, the Al₂O₃ and Al₂O₃-TiO₂ nanocoatings are the most effective in reducing the biocorrosion rate of the AZ31 alloy in the initial stages, while ensuring the material's biodegradability in subsequent stages.

This research was carried out under the financial support the Russian Science Foundation grant (project No. 24-73-00115).

With the development of nanotechnology, titania nanoparticles play a significant role in biomedical environmental applications. With the aim of better understanding bio-matrix/nanoparticle surface interactions, studying the influence of amino acids on the colloidal behavior of nanoparticles may provide valuable insights into the formation of the protein corona. In water nanoparticles, surface reconstruction and aggregation are determined to be different under varying pH levels and the presence of amino acids. However, there are not enough data to predict the influence of amino acids on the stability of anatase and rutile nanoparticles in the same conditions. In our work, we examined the colloidal properties of anatase and rutile nanoparticles, with an average size of 26 and 102 nm, respectively, and showed that the addition of five amino acids with contrasting surface charges (glutamic acid, cysteine, glycine, lysine, and arginine) enhances the aggregation of particles in an aquatic medium. In this work, we measured particle size distribution and zeta-potential in suspension with pH values ranging from 3 to 11. It has been revealed that under the same conditions, rutile nanoparticles have a lower pH dependence of the aggregation state compared to those of anatase, which are always more aggregated than rutile nanoparticles. The presence of amino acids tends to shift the pH of the isoelectric point of surface toward acidicity. For the particles in glutamic acid, glycine, and lysine, the highest degree of aggregation is achieved reasonably at a pH close to that of the isoelectric point. A contrasting effect of pH on the behavior of rutile and anatase nanoparticles was found in cysteine and arginine. Our findings showed that in an acidic medium (pH 3–5), aggregation depends more on pH; in a weakly acidic medium (5–7), it depends on the surface of the particles; and in an alkaline medium (7–11), on the nature of the amino acids.

Titanium dioxide (TiO₂) nanoparticles are widely used in various industries due to their low absorption coefficient, high dielectric permeability, good biocompatibility, high hardness, and photocatalytic activity. However, the colloidal properties (size, charge, sedimentation properties) of TiO₂ nanoparticles in aqueous solutions have not been sufficiently studied, and the results of studies are not comparable due to different experimental conditions and the diversity of nanoparticles produced, which limits the application of TiO₂ nanoparticle suspensions.

In this work, we determined the effects of the method (ultrasonic and mechanical) and duration (up to 60 min) of mixing and the pH of the solution (from 3 to 11) on the colloidal properties of TiO₂ nanoparticles in a 10 mM NaCl solution. The concentration of particles was 100 mg/L. Particle size distribution was determined using dynamic light scattering, zeta–potential was measured by using laser doppler electrophoresis, and light transmittance coefficient was estimated by spectrophotometry method. We examined two types of TiO₂ nanoparticles, namely anatase and rutile particles, with average particle sizes of 18 and 83 nm and a phase composition of anatase:rutile 87:13 and 73:27 wt.%, respectively.

It was found that prolonged treatment of suspensions (>30 min) led to surface overcharging and enhanced aggregation and sedimentation of nanoparticles. For both nanoparticles in an acidic environment, suspensions with maximum resistance to aggregation and sedimentation were formed. The sedimentation curves for suspensions were well described by a first-order kinetic equation (R²>0.9). All other things being equal, the behaviour of anatase nanoparticles is more sensitive to the pH value; meanwhile, rutile nanoparticles were more affected by the method of mixing.

The effect of pH and mixing method on the electrokinetic, dispersion, and sedimentation properties of suspensions provides valuable information that can be used to distinguish the colloidal stability of particles in aqueous solutions and broaden the application of TiO₂ nanoparticle suspensions.

Introduction: Magnetic colloids based on iron oxides, specifically maghemite (γ-Fe₂O₃), have emerged as significant nanostructures in biomedicine due to their superparamagnetic properties, which enable targeted therapies, magnetic hyperthermia, and photothermia, as well as functionalities as contrast agents in magnetic resonance imaging. In this context, magnetopolymeric NPs based on γ-Fe₂O₃ nuclei embedded into a poly(ε-caprolactone) (PCL) matrix and decorated with polyethylenimine (PEI) were developed and evaluated. Methods: Preparation of the magnetic nanocomposites (n = 3) was carried out by solvent evaporation. Iron oxide nuclei were obtained by chemical co-precipitation and were surface functionalized with PCL first and then with PEI. Reproducible preparation of these nanohybrids was demonstrated by determining particle size using photon correlation spectroscopy, high-resolution transmission electron microscopy (HRTEM), Fourier-transform infrared spectroscopy (FTIR), and electrophoresis (defining the effect of pH on the surface electrical charge of the colloid). Results: the PEI-decorated (γ-Fe₂O₃/PCL) (core/shell) nanohybrids were characterized by an average size of 232.9 ± 3.3 nm (polydispersity index: 0.259 ± 0.001). The evolution of the zeta potential values of the nanohybrids as a function of pH confirmed the successful embedment of the iron oxide cores, first into the PCL matrix, and then the surface decoration of the core/shell particles by a PEI ring. Finally, HRTEM analysis and FTIR spectra confirmed the successful formation of the (core/shell)/shell nanostructure. Conclusions: A reproducible methodology has been proposed for preparing PEI-decorated γ-Fe₂O₃/PCL NPs, which hold promise for applications in biomedicine.

The studied plant extract has demonstrated significant antioxidant, anti-inflammatory, antifungal, antibacterial, anticancer and psycho and neuroactive properties. In cosmetics, it has shown an additional distinctive fragrance, a refreshing sensation and calming effects on the skin. Liposomes are phospholipid bilayer nanocarriers with both hydrophilic and hydrophobic regions, enabling the encapsulation of water-soluble compounds in their aqueous core and fat-soluble compounds in their lipid membrane, making them ideal for incorporating plant extracts, whose bioactive compounds also often exhibit low stability. This study investigates the potential of the nano-encapsulation of a plant extract for enhanced topical delivery. The developed vesicles were produced using thin-film hydration, and lipid 1: lipid 2 ratios were optimized to obtain adequate particle characteristics (60:40, 75:25, 80:20). Particle size and polydispersity index (PDI) were determined by dynamic light scattering using a Zetasizer apparatus. For the determination of the encapsulation efficiency (EE%), a quantification method was developed using UV-Vis spectrophotometry. The results showed that liposomes without the extract exhibited a mean PDI of 0.164 - 0.176 and a particle size of 120.6 - 134.8 nm. After extract encapsulation (at 1, 2, 5 and 10 mg/mL), the mean PDI ranged from 0.180 to 0.434, with particle sizes between 106.5 and 136.3 nm. EE% for 80:20 liposomes ranged from 37 to 71% at 2, 5 and 10 mg/mL, yielding, respectively 1.3, 3.3 and 3.7 mg/mL of extract. The selected vesicles exhibited optimal characteristics with particle sizes below 200 nm and polydispersity index values below 0.200, which ensures stability and homogeneity of the vesicles, as well as effective skin retention, and EE% up to 70% demonstrated effective incorporation of the extract. This study presents a novel liposomal nano-encapsulation of aqueous plant extract, opening new avenues for its pharmacological and cosmetic utilization. Further studies will assess stability, release profiles and antioxidant activity.