Search

X-ray amorphous ribbons of aluminum-based alloys doped with transition (Ni, Fe) and rare earth (La) metals in various ratios were obtained by melt spinning. The mechanical characteristics and fracture surfaces of the ribbons under conditions of uniaxial tension with speeds from 0.01 to 10 mm/min were studied. It was shown that, with an increase in the rate in all investigated alloys, the strength limit increases and low plasticity remains. Inhomogeneous deformation is realized by the initiation and spread of shear bands. The mixed fracture surface indicates a brittle-viscous fracture with a high ratio of the viscous component. A significant influence of the scale factor on the strength characteristics of the ribbons was confirmed. The tensile strength of the ribbons increases with rising iron content and decreasing nickel content when the influence of the scale factor is excluded. It is experimentally shown on ribbons with a low-melting tin coating that local heating in shear bands reaches the melting point of tin of 231.9°C.

Ti–30Nb–10Ta–5Zr alloy was produced and studied in the work. Plates and wires were made of this alloy. The alloy was shown to have pure β-crystalline phase and to possess the required mechanical properties. Microstructures with a height of the order of several hundred nm, located at a distance of 1.5–2.0 μm were observed on the surface of the alloy. From the point of view of reactive oxygen species generation and long-lived reactive protein species formation, the Ti–30Nb–10Ta–5Zr alloy is more preferrable than nitinol. Cultivation of cell cultures on Ti–30Nb–10Ta–5Zr surfaces resulted in high mitotic index (2%) and low content of non-viable cells (

The paper describes synthesis and testing of novel biodegradable polylactide-based polymer membranes with desired mechanical properties, which are capable of sustained and directed release of biomacromolecules with high molecular weight (in particular, streptokinase; m.w. 47 kDa). Streptokinase is a pharmaceutical agent, possessing a pronounced thrombolytic activity. The membranes synthesized had a percentage elongation of 2–11% and tensile strength of 25–85 MPa. They were biodegradable – yet being stored in aqueous media in the absence of biological objects, would be dissolved by no more than 10% in 6 months. The synthesized membranes were capable of controlled release of streptokinase into the intercellular space, with the enzyme retaining more than 90% of its initial activity. The rate of streptokinase release from the membranes varied from 0.01 to 0.04 mg/day per cm2 of membrane surface. The membrane samples tested in the work did not have any short-term toxic effects on the cells growing de novo on the membrane surface. The mitotic index of those cells was approximately 1.5%, and the number of non-viable cells on the surface of the polymer films did not exceed 3–4% of their total amount. The implantation of the synthesized polymers – as both individual films and coatings of nitinol stents – was not accompanied by any postoperative complications. The subsequent histological examination revealed no abnormalities. Two months after the implantation of polymer films, only traces of polylactide were found in the implant-surrounding tissues. The implantation of stents coated with streptokinase-containing polymers resulted in the formation of a mature and thick connective-tissue capsules. Thus, the polylactide membranes synthesized and tested in this work are biodegradable, possess the necessary mechanical properties and are capable of sustained and directed release of streptokinase macromolecules.

The efficiency of controlled drug release systems is largely determined by the properties of the matrix material. Our research team developed a process for production of biodegradable polymer films based on high-molecular-weight polylactide with properties necessary for medical and agricultural applications. A process for incorporation of drugs (gentamicin sulfate, lincomycin hydrochloride, cefotaxime) into high-molecular-weight polylactide films was developed. The mechanical properties and biocompatibility of the obtained polymers were studied. The films based on high-molecular-weight polylactide were found to have high strength characteristics (yield strength of about 49 MPa, tensile strength of 54 MPa). With increasing drug concentration, the strength characteristics of polymer films linearly decrease. The biocompatibility of the polymers was demonstrated on both cell cultures and implantation into animal models.

This review is devoted to modern technologies for various modifications of a surface of orthopedic implants made from titanium alloys. This approach will allow improving such characteristics of the implants as a corrosion resistance, biocompatibility and osteointegration. Modifications of titanium alloys with hydroxyapatite and calcium phosphate, multifunctional polymer or antibacterial coatings are considered. Analysis of the studies shows that the implant material can only provide a certain degree of biocompatibility and corrosion resistance, and that the nature and design of its surface have a strong influence on the body's response. Surface modification of implants is a good approach to overcome and solve various problems associated with the disadvantages of titanium alloys for orthopedic implants. titanium alloys, orthopedic implant, functional coating, ceramic coating, polymer coating, antibacterial coating The reported study was funded by RFBR, project No 19-18-50015.

Research of dynamics of nonlinear corrosion processes of non-nickel titanium shape memory alloy Ti-20Nb-10Ta is performed. Samples were placed in mediums imitating physiological liquids, with ðÍ from 1.68 to 9.18. 3 types of samples were used: in an initial state, after thermal (annealing) and surface mechanical treatment. After annealing, there is a slight narrowing of the X-ray peaks, which indicates stress relief. New phases are not allocated. The alloy is a substitution solution with a b-Ti lattice. The greatest release of titanium ions was observed in solution with the sourest environment and samples after annealing. Release of niobium and tantalum ions in solution with any acidity was not observed.

A team of authors developed a technology for producing biocompatible biodegradable polymer films based on high-molecular polylactide with the properties necessary for medical and agricultural use. A technology has been developed for the inclusion of active substances (gentamicin sulfate, lincomycin hydrochloride, cefotaxime) into films of high-molecular polylactide. The rate of release of active substances from polylactide can vary with time as a decaying exponent, as well as a function close to linear. The process of release of active substances is significantly affected by the pH of the surrounding film of the solution. It was found that the dynamics of release of active substances from biocompatible biodegradable polymer films created on the basis of high-molecular polylactide depends on the properties of the substance immobilized in the film, the technology of the film and the conditions under which the extraction is carried out. The technical parameters of biocompatible biodegradable polymer films based on high-molecular polylactide are quite suitable for the manufacture of coatings of stents and prostheses with prolonged and controlled release of drugs into the surrounding tissues, as well as for use in agriculture to increase the safety of the harvest.

A process was developed for producing biocompatible and biodegradable polymer films based on high-molecular-weight polylactide with properties necessary for medical and agricultural applications. A method was devised for the inclusion of active substances (gentamicin sulfate, lincomycin hydrochloride, or cefotaxime) into high-molecular-weight polylactide films. The rate of release of active substances from polylactide can vary with time according to a decaying exponential law or nearly linearly. The release of active substances is significantly affected by pH of the solution surrounding the film. It was found that the dynamics of release of active substances from biocompatible biodegradable polymer films based on high-molecular-weight polylactide depends on the properties of the immobilized substance, the film preparation method, and the conditions of extraction. The biocompatible biodegradable polymer films based on high-molecular-weight polylactide are quite suitable for the manufacture of coatings for stents and prostheses with prolonged and controlled drug release into the surrounding tissues and for agricultural applications to improve crop preservation.

Various poly(lactic-co-glycolic acid)-based polymeric films with various molecular weights were obtained. The mechanical characteristics of these films were investigated. It was shown that the obtained polymer films do not have a short-term toxic effect on mammalian cells. The percentage of actively dividing cells on such polymer films is 1.5–3.0 times higher than when grown on culture glass, and, accordingly, the cell layer is formed faster. The obtained poly(lactic-co-glycolic acid)-based polymer films are biocompatible.

A biocompatible material characterized by gradient structure titanium nickelide–tantalum–biodegradable polymer layer was designed for the manufacture of medical implants. The mechanical characteristics of the material and components were studied. The structure and composition were determined by SEM and Auger electron spectroscopy. The formation of surface layers does not significantly affect the mechanical characteristics of the support; high adhesion between the layers and the support is observed.

—A method of estimating the mechanical properties of the surface layer of working elements made of polycrystalline superhard composites based on cubic boron nitride involving sclerometry at scanning by a diamond indenter has been proposed. Theoretical validation of the method has been provided and thermodynamic parameters of mechanical properties of the surface layer (the value of the activation barrier of initiation of the entropy production process and the capacity for entropy production at a metered impact) have been investigated. Results of the experiments on the performance efficiency of cutter tools made of superhard composites fabricated by lathing of tempered steel are provided and corroborate the theoretical assumptions.

Using the methods of electric arc melting, intermediate heat treatments, and consecutive intensive plastic deformation, a Ti&ndash, Nb&ndash, Zr alloy wire with a diameter of 1200 &mu, m was obtained with a homogeneous chemical and phase (&beta, Ti body-centered crystal lattice) composition corresponding to the presence of superelasticity and shape memory effect, corrosion resistance and biocompatibility. Perhaps the wire structure is represented by grains with a nanoscale diameter. For the wire obtained after stabilizing annealing, the proof strength Rp0.2 is 635 MPa, tensile strength is 840 MPa and Young&rsquo, s modulus is 22 GPa, relative elongation is 6.76%. No toxicity was detected. The resulting wire is considered to be promising for medical use.

The mechanical characteristics of a titanium nickelide alloy are studied depending on the surface machining. The additional processing improves the characteristics.

The study of the X-ray contrast of a nickel-free shape memory alloy TiNbTaZr for medical purposes of various compositions was carried out by theoretical calculation of the linear attenuation coefficient and the evaluation of the linear attenuation coefficient by the flaw detection method due to obtaining a contrast image. From the data obtained, it can be argued that all the obtained Ti-Nb-Ta-Zr materials have a radiopacity, the more the higher the content of niobium and tantalum.

Nanoscale and microscale surface layers of silver on flat and wire NiTi and SiO2 substrates were produced by vacuum magnetron sputtering. The structure and the composition of samples were determined by SEM, Auger electron spectroscopy (AES), and X-ray diffractometry. The thickness and the structure of surface layers were affected by the sputtering distance and time.

A technology for producing a new homogeneous Ti–20Nb–13Ta–5Zr alloy has been developed. It is shown that the alloy is single-phase with a β-Ti type crystal lattice. The alloy has the required mechanical properties (tensile strength of about 745 MPa). On the surface of plates and wire made of alloy, a relief of micro- and nanoscale is observed. In terms of the ability to generate reactive oxygen species and long-lived reactive protein species, the Ti–20Nb–13Ta–5Zr alloy is more preferable than nitinol. It was established that cell cultures growing on plates or wire made of Ti–20Nb–13Ta–5Zr alloy had a significant mitotic index (2%). The number of viable cells was at least 95–96% of the overall cell count. According to the results of implantation of the alloy in the form of plates or wire ring to animals, it can be concluded that the alloy is biocompatible. The morphology of the surface of the samples did not change after biological experiments. It can be assumed that the alloy Ti–20Nb–13Ta–5Zr is a material potentially suitable for medical applications.

The microstructure and microhardness of Ti-20Nb-7.5Ta and Ti-20Nb-10Ta alloys (at. %) after smelting and after homogenizing annealing at 900°C and 950°C for 12 hours were studied. It was shown that, after smelting, the alloys have a dendritic structure, and after annealing, they have a polycrystalline structure with equiaxed grains. It is also shown that annealing leads to an increase in the microhardness of alloys.

An RTV grade siloxane film with a different percentage of catalyst was obtained. The microstructure of the surface of polymer films based on PTB grade siloxane was studied and the effect of the K-18 catalyst concentration on the thickness and microstructure of the obtained films was shown.

A RTV grade siloxane film with a different percentage of catalyst was obtained. The mechanical properties of polymer films based on RTV grade siloxane are studied, as well as the effect of K-18 catalyst concentration on thickness, strength and ductility the properties of the obtained films was shown.

The regularities of the titanium surface and transitional monolayers formation using magnetron sputtering and ion bombardment depending on the deposition time, adhesion parameters and mechanical characteristics are investigated. Saturation regions of the surface and transition layers are noted. The transition layer provides high adhesion of the surface layer to the substrate. The application of a titanium surface layer to a nitinol reduces elongation and yield strength but increases tensile strength, and as the deposition time increases, the elongation decreases very slightly, and the yield strength and strength increase.

Corrosion resistance of a Ti - (20-30) Nb - 5Zr shape memory alloy were studied. The structure and composition of the materials were determined using SEM and Auger electron spectrometry. Electro-chemical parameters and alloy dissolution in physiological modeling media were investigated. It has been shown that the alloys are quite corrosion-resistant: no dissolution and high Ebd potential were observed.

The effect of heat treatment on the static mechanical properties of a Ti-20Nb-10Ta shape memory alloy in the form of thin wire is studied. After annealing at 600 °C for 20 minutes, a low modulus of elasticity was obtained. The best strength and ductility indicators were obtained after annealing at a temperature of 800 °C during 60 minutes.

The novelty of the study is the development, creation, and investigation of biodegradable polymeric membranes based on polylactide, that are capable of directed release of large molecular weight biomolecules, particularly, prourokinase protein (MW = 46 kDa). Prourokinase is a medication with significant thrombolytic activity. The created membranes possess the required mechanical properties (relative extension value from 2% to 10%, tensile strength from 40 to 85 MPa). The membranes are biodegradable, but in the absence of living cells in a water solution they decompose by less than 10% in half a year. The created membranes are capable of controlled prourokinase release into intercellular space, and the total enzymatic activity of prourokinase does not decrease by more than 12%. The daily release of prourokinase from one square centimeter of the membrane ranges from 1 to 40 &mu, g per day depending on the technique of membrane preparation. The membranes have no acute toxic effect on cells accreting these surfaces de novo. The number of viable cells is at least 96%&minus, 97% of the overall cell count. The mitotic index of the cells growing on the surface of the polymeric films comprised around 1.5%. Histological examination did not reveal any disorders in tissues of the animals after the implantation of polymer membranes based on polylactide, both alone and as components of stent cover. Implantation of stents covered with prourokinase-containing polymers led to the formation of a mature connective tissue capsule that is thicker than in the case of uncovered stents. Thus, various polylactide-based biodegradable polymeric membranes possessing the required mechanical properties and capable of prolonged and directed release of prourokinase macromolecules are developed and investigated in the study.

A technology for obtaining materials from nanostructured nitinol with titanium- or tantalum-enriched surface layers was developed. Surface layers enriched with titanium or tantalum were shown to provide a decrease in the formation of reactive oxygen species and long-lived protein radicals in comparison to untreated nitinol. It was determined that human peripheral vessel myofibroblasts and human bone marrow mesenchymal stromal cells grown on nitinol bases coated with titanium or tantalum-enriched surface layers exhibit a nearly two times higher mitotic index. Response to implantation of pure nitinol, as well as nano-structure nitinol with titanium or tantalum-enriched surface layers, was expressed though formation of a mature uniform fibrous capsule peripherally to the fragment. The thickness of this capsule in the group of animals subjected to implantation of pure nitinol was 1.5 and 3.0-fold greater than that of the capsule in the groups implanted with nitinol fragments with titanium- or tantalum-enriched layers. No signs of calcinosis in the tissues surrounding implants with coatings were observed. The nature and structure of the formed capsules testify bioinertia of the implanted samples. It was shown that the morphology and composition of the surface of metal samples does not alter following biological tests. The obtained results indicate that nano-structure nitinol with titanium or tantalum enriched surface layers is a biocompatible material potentially suitable for medical applications.

Alloys possessing a shape memory effect and mechanical characteristics similar to the behavior of living tissues have been already used for years as the material for production of medical devices, including implants, for example stents, without the need for additional devices except catheter-carrier. However, most of these alloys contain elements (including on its surface) which is toxic for organism. To satisfy the requirements of biochemical compatibility, the alloy should contain only safe elements as alloy components, which include: Ti, Nb, Ta, Zr. The possibility of obtaining of Ti-Nb-Ta-Zr thin wire was investigated. The structure was determined with the use of the optical microscope, X-ray diffractometer, scanning electron microscope (SEM) and Auger spectrometer. Optimal conditions for smelting were chosen. It was noted that a uniform structure was obtained for all compositions, before and after homogenizing annealing. The ingots have a dendritic structure. Niobium and zirconium were uniformly distributed throughout the sample, tantalum was concentrated in the dendrites themselves, titanium was predominantly in the regions between the dendritic axes, but is also found in it. X-ray diffractometry indicates that the elements of the alloy were not distributed in it by separate fragments, but were united in a single structure. The optimal annealing temperature of Ti-(20-30)Nb- (10-13)Ta-5Zr alloys was noted in the range from 600 to 900°C. The grain boundaries after plastic deformation and heat treatment were not identified in a microstructural analysis, which indicates that there was no recrystallization. It is possible that nanostructure was formed. The morphology of wires of any composition after drawing shows a high heterogeneity, two types of surfaces of different composition alternate - areas with a high content of carbon and with a high content of oxygen were observed. After mechanical treatment the surface, its uniformity increases.

Nanoscale and microscale surface layers of Ta, Ti, Cu, and Sn on flat and wire NiTi, Cu, Ti, and SiO2 substrates were produced by vacuum magnetron sputtering. The structure and the composition of samples were determined by SEM, AES, Auger spectroscopy, and X-ray diffractometry. The thickness and the structure of surface layers were affected by the sputtering distance and power and the bias voltage at the substrate.

We have obtained nanoscale and microscopic surface tantalum layers on NiTi flat substrates and wires. The structure and composition of the samples were determined by scanning electron microscopy, Auger electron spectroscopy, and X-ray diffraction. With increasing sputtering time, the thickness of the surface layer increases nonlinearly. The transition layer ensures strong adhesion of the surface layer to the substrate.

The corrosion resistance of nanostructural nitinol in solutions with pH from 1.68 to 9.18 for a long time is investigated. The metal concentration in solution was determined using atomic emission spectrometry with inductively coupled plasma. The ion yield is inhibited in NaCl and hardly so in acidic media, and corrosion is not observed in alkaline medium. The corrosion resistance increases by polishing and deteriorates with annealing. The nanostructure promotes a lower yield of nickel ions.

Nanostructural nitinol is investigated before and after storage for a long time in solutions simulating pH of physiological liquids. The structure and composition are determined by SEM, TEM, and Auger spectroscopy. The material base is the B2 phase in the form of fibers 30–70 nm in diameter. Polishing promotes the formation of a thin homogeneous surface layer of titanium oxide, which thickens after solution storage; and annealing, the layer unchanging, thick, and heterogeneous.

A process for manufacture of chitosan-based biodegradable biopolymer membranes suitable for medical applications was developed. A technology for inclusion of broad spectrum antibiotics into the chitosan membranes was elaborated. The effects of pH of the solution surrounding the membranes and the initial solvent chosen for chitosan on the kinetics of release of antibiotics from the membranes were studied. It was demonstrated that the kinetics of drug release from the chitosan-based biodegradable biopolymer membranes depends on the properties of substance immobilized in the membrane, the membrane manufacture process, and extraction conditions.

The properties of nanostructured nitinol (Ni, 55.91 wt %; Ti, 44.03 wt %) in the initial state and after mechanical and the thermal treatment and a composite of nitinol with a tantalum surface layer obtained by magnetron sputtering have been studied. Compared with microstructured nitinol, the use of nanostructured nitinol for medical appliances, like stent, has great opportunities due to better corrosion resistance in solutions that model the physiological media of a human organism and the decreased diffusion of nickel ions into solution below the admitted average dietary intake of 200–300 mg/day in solutions of any acidity. Surface mechanical polishing increases its corrosion resistance by two to three times more. Compared with nitinol, the composite of nitinol with a tantalum surface layer is ∼7–11% better by strength, plasticity, and surface microhardness and characterized by the absence of a corrosion processes and diffusion of metal ions into solution.

Nano- and micro-dimensional surface layers of titanium on flat and wire NiTi substrates were obtained. The structure and composition of the samples was determined using SEM, AES, Auger spectroscopy and X-ray diffraction. With increasing deposition time, the thickness of the surface layer increases nonlinearly. The transition layer provides high adhesion of the surface layer to the substrate.

The formation of the Ti– (20–30) Nb-5Zr alloys (at.%) structure was studied. The structure of the samples was determined using an light microscope. It is shown that after melting by the method of vacuum arc melting, the alloys have a developed dendritic structure. Homogenizing annealing at a temperature of 900 °C does not lead to the destruction of the dendritic structure and recrystallization. Annealing at a temperature of 1000 °C completely destroys the dendritic structure in the alloys.

The study of the degradation of films based on polylactide in phosphate buffer solution. The effect of the change in the molecular weight of polylactide on the polymer degradation process is shown. With an increase in the molecular weight of polylactide, there is a slight increase in the rate of degradation of the polymer.