Obtaining a Wire of Biocompatible Superelastic Alloy Ti-28Nb-5Zr.

Using the methods of electric arc melting, intermediate heat treatments, and consecutive intensive plastic deformation, a Ti-Nb-Zr alloy wire with a diameter of 1200 µm was obtained with a homogeneous chemical and phase (ß-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'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.

Ion Release and Surface Characterization of Nanostructured Nitinol during Long-Term Testing.

The corrosion resistance of nanostructured nitinol (NiTi) was investigated using long-term tests in solutions simulating physiological fluids at static conditions, reflecting the material structure and metal concentration in the solutions. Mechanical polishing reduced the ion release by a factor of two to three, whereas annealing deteriorated the corrosion resistance. The depassivation and repassivation of nitinol surfaces were considered. We found that nanostructured nitinol might increase the corrosion leaching of titanium into solutions, although the nickel release decreased. Metal dissolution did not occur in the alkaline environment or artificial plasma. A Ni-free surface with a protective 25 nm-thick titanium oxide film resulted from soaking mechanically treated samples of the NiTi wire in a saline solution for two years under static conditions. Hence, the medical application of nanostructured NiTi, such as for the production of medical devices and implants such as stents, shows potential compared with microstructured NiTi.

The Effect of Gold Nanoparticle Concentration and Laser Fluence on the Laser-Induced Water Decomposition.

This Article covers the influence of the concentration of gold nanoparticles on laser-induced water decomposition. It was established that addition of gold nanoparticles intensifies laser-induced water decomposition by almost 2 orders of magnitude. The water decomposition rate was shown to be maximal at a nanoparticle concentration around 1010 NP/mL, whereas a decrease or increase of nanoparticle concentration leads to a decrease of water decomposition rate. It was demonstrated that, if the concentration of nanoparticles in water-based colloid was less than 1010 NP/mL, laser irradiation of the colloid caused formation of molecular hydrogen, hydrogen peroxide, and molecular oxygen. If the concentration of nanoparticles exceeded 1011 NP/mL, only two products, molecular hydrogen and hydrogen peroxide, were formed. Correlations between the water decomposition rate and the main optical and acoustic parameters of optical breakdown-generated plasma were investigated. Variants of laser-induced decomposition of colloidal solutions of nanoparticles based on organic solvents (ethanol, propanol-2, butanol-2, diethyl ether) were also analyzed.

Unmodified hydrated С60 fullerene molecules exhibit antioxidant properties, prevent damage to DNA and proteins induced by reactive oxygen species and protect mice against injuries caused by radiation-induced oxidative stress.

Unmodified hydrated С60 fullerene molecules (C60UHFM) were shown to reduce the formation ROS in water and 8-oxoguanine in DNA upon ionizing radiation impact. C60UHFM efficiently eliminate long-lived protein radicals arising after irradiation. In irradiated mice C60UHFM reduce the rate of single/double-strand DNA breaks and amount of chromosomal breaks. The radioprotective activity of C60UHFM was estimated by the survival rate of animals; the dose modification factor for animal survival was 1.3. Hematological tests showed that C60UHFM injection in mice prior to irradiation results in a decrement of irradiation-induced leucopenia and thrombocytopenia. Histological analysis testified that C60UHFM provide significant protection of small intestine tissues in mice against irradiation-induced damage. The obtained data assume that the radioprotective properties of C60UHFM are determined by their antioxidant, antiradical and DNA-protective qualities. Thus, it was demonstrated that C60UHFM are a novel antioxidant and radioprotective agent capable of substantial reduction of the harmful effects of ionizing radiation.

Biocompatibility of new materials based on nano-structured nitinol with titanium and tantalum composite surface layers: experimental analysis in vitro and in vivo.

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.