Structure and properties of composite surface layers produced on NiTi shape memory alloy by a hybrid method.

A hybrid process that combines oxidation under glow-discharge conditions with ion beam-assisted deposition (IBAD) has been applied to mechanically polished NiTi shape memory alloy in order to produce composite surface layers consisting of a TiO2 layer and an external carbon coating with an addition of silver. The produced surface layers a-C(Ag) + TiO2 type have shown increased surface roughness, improved corrosion resistance, altered wettability, and surface free energy, as well as reduced platelet adhesion, aggregation, and activation in comparison to NiTi alloy in initial state. Such characteristics can be of great benefit for cardiac applications.

Formation of Nitrogen Doped Titanium Dioxide Surface Layer on NiTi Shape Memory Alloy.

NiTi shape memory alloys are increasingly being used as bone and cardiac implants. The oxide layer of nanometric thickness spontaneously formed on their surface does not sufficiently protect from nickel transition into surrounding tissues, and its presence, even in a small amount, can be harmful to the human organism. In order to limit this disadvantageous phenomenon, there are several surface engineering techniques used, including oxidation methods. Due to the usually complex shapes of implants, one of the most prospective methods is low-temperature plasma oxidation. This article presents the role of cathode sputtering in the formation of a titanium dioxide surface layer, specifically rutile. The surface of the NiTi shape memory alloy was modified using low-temperature glow discharge plasma oxidation processes, which were carried out in two variants: oxidation using an argon + oxygen (80% vol.) reactive atmosphere and the less chemically active argon + air (80% vol.), but with a preliminary cathode sputtering process in the Ar + N2 (1:1) plasma. This paper presents the structure (STEM), chemical composition (EDS, SIMS), surface topography (optical profilometer, Atomic Force Microscopy-AFM) and antibacterial properties of nanocrystalline TiO2 diffusive surface layers. It is shown that prior cathodic sputtering in argon-nitrogen plasma almost doubled the thickness of the produced nitrogen-doped titanium dioxide layers despite using air instead of oxygen. The (TiOxNy)2 diffusive surface layer showed a high level of resistance to E. coli colonization in comparison with NiTi, which indicates the possibility of using this surface layer in the modification of NiTi implants' properties.

Plasma Modification of Carbon Coating Produced by RF CVD on Oxidized NiTi Shape Memory Alloy under Glow-Discharge Conditions.

Our previous work has shown that for cardiac applications, combining low-temperature plasma oxidation with an amorphous carbon coating (a-C:N:H type) constitutes a prospective solution. In this study, a short-term modification by low-temperature oxygen plasma is proposed as an example and a method for shaping the topography and surface energy of the outer amorphous carbon coating, produced via the Radio-Frequency Chemical Vapour Deposition (RFCVD) method on NiTi alloy oxidized under glow-discharge conditions. This treatment alters the chemical composition of the outer zone of the surface layer. A slight increase is also noted in the surface roughness at the nanoscale. The contact angles were shown to increase by about 20% for water and 30% for diiodomethane, while the surface free energy decreased by ca. 11%. The obtained results indicate that even short-term contact with low-temperature plasma can shape the surface properties of the carbon coating, an outcome which shows potential in terms of its use in medical applications.

A new formulation of fluticasone propionate/salmeterol in a metered-dose inhaler (MDI HFA) allows for the reduction of a daily dose of corticosteroid and provides optimal asthma control - A randomized, multi-center, non-inferiority, phase IV clinical study.

BACKGROUND: Improvement of the delivery method of inhaled corticosteroids and subsequent dose reduction can minimize the risk of unfavorable outcomes while providing optimal asthma control. OBJECTIVE: This randomized, multi-center, non-inferiority, phase IV clinical study compared the efficacy and safety of a new formulation of fluticasone propionate/salmeterol (250 µg/50 µg, twice daily) administered in a metered-dose inhaler hydrofluoroalkane (MDI HFA) with a dry-powder inhaler (DPI) containing fluticasone propionate/salmeterol (500 µg/50 µg, twice daily). METHODS: Adults with asthma (n = 231) were randomly assigned to either the study group (treated for 12 weeks with fluticasone propionate/salmeterol MDI HFA) or a control group (treated for 12 weeks with fluticasone propionate/salmeterol DPI). Asthma symptoms, exacerbations, short-acting ß2-agonist (SABA) use, physical activity, lung function, and general health status were assessed during four study visits. RESULTS: Compared with the reference drug, the study drug decreased the incidence of daytime and night-time asthma symptoms, asthma exacerbations, self-administration of SABA, and the limitation of physical activity. Comparable improvement in peak expiratory flow ([MDI HFA] from 6.2 ± 0.2 to 6.6 ± 0.2 l/s vs. [DPI] from 6.0 ± 0.2 to 6.9 ± 0.2 l/s; p > 0.05), forced expiratory volume in one second, and forced vital capacity were obtained in both groups. Significantly lower incidence of hoarseness was observed in the study group ([MDI HFA] 0.0% vs. [DPI] 2.8%; p = 0.0267); no major differences were found for other adverse events. CONCLUSIONS: Fluticasone propionate/salmeterol (250 µg/50 µg, twice daily) MDI HFA provides optimal asthma control and is non-inferior to fluticasone propionate/salmeterol (500 µg/50 µg, twice daily) DPI.

Effect of Nitrided and Nitrocarburised Austenite on Pitting and Crevice Corrosion Resistance of 316LVM Steel Implants.

Harmful lesions occur in the body around multielement stabilisers made of AISI 316 LVM (Low Vacuum Melted) steel, caused by products of pitting, fretting or crevice corrosion. Preventing the effect is possible by modifying the surface of the steel implants. Therefore, the goal of the paper is the comparison of the mechanical and physiochemical properties of plates for treating deformations of the anterior chest wall made of AISI 316 LVM steel, subjected to diffusion and sterilisation processes and exposed to Ringer's solution. The surface of the implants was subjected to electrochemical polishing, chemical passivation and, in order to modify their properties, nitrocarburised and nitrided diffusion layers were created on selected stabilisers under glow discharge conditions with the use of an active screen at a temperature of 420 °C, over 60 min. The conducted studies involved the examination of the microstructure of the formed layers, surface roughness testing, analysis of contact angles and surface free energy, examination of resistance to pitting and crevice corrosion and examination of nanohardness. On the basis of the results of the conducted studies, it was established that the most advantageous set of properties after sterilisation and exposure to Ringer's solution was displayed by implants with a formed diffusion nitrocarburised layer.

Structure and physico-mechanical properties of low temperature plasma treated electrospun nanofibrous scaffolds examined with atomic force microscopy.

Electrospun nanofibrous scaffolds are willingly used in tissue engineering applications due to their tunable mechanical, chemical and physical properties. Additionally, their complex openworked architecture is similar to the native extracellular matrix of living tissue. After implantation such scaffolds should provide sufficient mechanical support for cells. Moreover, it is of crucial importance to ensure sterility and hydrophilicity of the scaffold. For this purpose, a low temperature surface plasma treatment can be applied. In this paper, we report physico-mechanical evaluation of stiffness and adhesive properties of electrospun mats after their exposition to low temperature plasma. Complex morphological and mechanical studies performed with an atomic force microscope were followed by scanning electron microscope imaging and a wettability assessment. The results suggest that plasma treatment can be a useful method for the modification of the surface of polymeric scaffolds in a desirable manner. Plasma treatment improves wettability of the polymeric mats without changing their morphology.

Properties of Ti-6Al-7Nb titanium alloy nitrocarburized under glow discharge conditions.

PURPOSE: The paper presents the results of physicochemical and mechanical properties of the Ti-6Al-7Nb alloy with surface modified by formation of a diffusive nitrocarburized layer deposited in a low-temperature plasma process. The main aim of the study was to evaluate the influence of steam sterilization and exposure to Ringer's solution on the utility properties of the alloy. METHODS: Based on the study of the microstructure, roughness, wettability, resistance to pitting corrosion, ion infiltration and mechanical properties, the usefulness of the proposed method of surface treatment for clinical application was proven. RESULTS: Deposition of the nitrocarburized layer increased the surface roughness and surface hardness, but also reduced the contact angle, and corrosion resistance with respect to the polished surfaces. The nitrocarburized layer is a barrier against the infiltration of ions to the solution and sterilization and exposure to Ringer solution have greater effect on the physicochemical properties rather than on the mechanical ones. CONCLUSION: It was found that sterilization, and exposure to Ringer's solution greatly affect the change of physicochemical properties rather than mechanical properties for both nitrocarburized layers and the Ti-6Al-7Nb alloy of mechanically polished surface.