Flexible and Tough Superelastic Co-Cr Alloys for Biomedical Applications.

The demand for biomaterials has been increasing along with the increase in the population of elderly people worldwide. The mechanical properties and high wear resistance of metallic biomaterials make them well-suited for use as substitutes or as support for damaged hard tissues. However, unless these biomaterials also have a low Young's modulus similar to that of human bones, bone atrophy inevitably occurs.

Electronegativity Difference as a Descriptor for the Oxidation-Inhibiting Effect of the Alloying Element during the Early Stages of Titanium Oxidation.

Degradation of the mechanical properties of α-titanium, which is used to manufacture parts of jet engines, due to high-temperature oxidation is detrimental for the engine components. Therefore, to overcome this problem there are ongoing endeavors to develop novel oxidation-resistant titanium alloys and improve the properties of the existing ones. In an effort to understand the effect of alloying on oxidation of the α-Ti(0001) surface and to identify descriptors for rational design of oxidation-resistant alloys, in this work, using density functional theory-based calculations, we studied oxygen sorption and surface to subsurface diffusion on pure and alloyed α-Ti(0001) surfaces.

Effect of Precursor Deficiency Induced Ca/P Ratio on Antibacterial and Osteoblast Adhesion Properties of Ag-Incorporated Hydroxyapatite: Reducing Ag Toxicity.

Ag-containing hydroxyapatite (HA) can reduce risks associated with bacterial infections which may eventually require additional surgical operations to retrieve a failed implant. The biological properties of HA in such applications are strongly affected by its composition in terms of dopants as well as Ca/P stoichiometry, which can be easily controlled by altering processing parameters, such as precursor concentrations. The objective of this in vitro study was to understand the effect of variations in HA precursor solutions on antibacterial properties against   and for promoting osteoblast (bone-forming cell) adhesion on Ag incorporated HA (AgHA) which has not yet been investigated.

Formation of carbon-added anatase-rich TiO layers on titanium and their antibacterial properties in visible light.

Objective: To avoid risk of infections associated with dental implants, thermal oxidation processes for practical dental Ti alloys were studied for both high bonding strength and antibacterial properties in visible light.

Methods: Two-step thermal oxidation, comprising carburization (first step of treatment: in Ar-1%CO gas) and subsequent oxidation (second step of treatment: in air), was conducted on commercially pure (CP) Ti, Ti-6Al-4V (Ti64), and Ti-6Al-7Nb (Ti67) alloys to form TiO layers. Their bonding strengths and antibacterial properties against Escherichia coli (E.

Using HAADF-STEM for atomic-scale evaluation of incorporation of antibacterial Ag atoms in a β-tricalcium phosphate structure.

Structural evaluation of ionic additions in calcium phosphates that enhance their performance is a long-lasting area of research in the field of biomedical materials. Ionic incorporation in β-tricalcium phosphate (β-TCP) structures is indispensable for obtaining desirable properties for specific functions and applications. Owing to its complex structure and beam-sensitive nature, determining the extent of ion incorporation and its corresponding location in the β-TCP structure is challenging.

Fabrication of Ag and Ta co-doped amorphous calcium phosphate coating films by radiofrequency magnetron sputtering and their antibacterial activity.

Coating of amorphous calcium phosphate (ACP) on titanium (Ti) implants is a promising technique for enhancing bone-forming ability because of its dissolution in vivo. Surgical site infection is one of the serious complications associated with implant devices. In order to achieve both the antibacterial properties and bone-forming ability on the surface of Ti implants, Ag-doped ACP coating films were fabricated.

COX-2 induces T cell accumulation and IFN-γ production during the development of chromium allergy.

Chromium (Cr) is commonly added into various metal alloys to improve some mechanical properties such as corrosion resistance, strength, and workability. However, Cr is also known to be a metal allergen for some individuals. Metal allergy is a T cell-mediated disease with symptoms of inflammation and swelling that involve inflammatory cytokines and prostaglandins.

Visible-light-responsive antibacterial activity of Au-incorporated TiO layers formed on Ti-(0-10)at%Au alloys by air oxidation.

Rutile TiO layers were formed on substrates of Ti-(0-10)at%Au alloys by a simple process of air oxidation, and their antibacterial activities were evaluated under visible-light irradiation (λ ≥ 400 nm). Au was introduced into the TiO layers on Ti-(1-10)at%Au alloys and existed as both metallic Au nanoparticles and dissolved Au ions. The TiO layers that formed on Ti-5at%Au and Ti-10at%Au alloys exhibited visible-light photocatalytic activity, that is, degradation of stearic acid and antibacterial activity against Escherichia coli.

Effect of Si on the oxidation reaction of α-Ti(0 0 0 1) surface: molecular dynamics study.

We present our molecular dynamics (MD) study of the effect of Si on the oxidation of α-Ti(0001) surfaces. We varied the Si concentration in the first layer of the surface from 0 to 25 at.% and the oxygen coverage () on the surface was varied up to 1 monolayer (ML).

TRAV7-2*02 Expressing CD8⁺ T Cells Are Responsible for Palladium Allergy.

While metallic biomaterials have led to an improvement in the quality of life, metal allergies, especially to palladium (Pd), has caused a recent increase in allergic patients. Metal allergy is known to be a T cell-mediated delayed-type hypersensitivity (DTH); however, the pathogenic T cell subsets and the specific T cell receptor (TCR) have not been identified. Therefore, we attempted to identify the pathogenic T cells responsible for Pd allergy.

In vitro performance of Ag-incorporated hydroxyapatite and its adhesive porous coatings deposited by electrostatic spraying.

Bacterial infection of implanted materials is a significant complication that might require additional surgical operations for implant retrieval. As an antibacterial biomaterial, Ag-containing hydroxyapatite (HA) may be a solution to reduce the incidences of implant associated infections. In this study, pure, 0.

In vitro evaluation of Ag-containing calcium phosphates: Effectiveness of Ag-incorporated β-tricalcium phosphate.

Development of bioceramics with antibacterial activity and without cytotoxicity would be beneficial for preventing infection associated with implants. This study aimed to capitalize on the antibacterial properties of silver (Ag) incorporated in or coexisting in metallic form with calcium phosphates (CaPs). The in vitro dissolution behavior, antibacterial activity, and cytotoxicity of Ag-containing CaPs with different phase fractions of hydroxyapatite (HA) and β-tricalcium phosphate (β-TCP) were evaluated.

Preparation of orthophosphate glasses in the MgO-CaO-SiO2-Nb2O5-P2O5 system.

Background: Niobia/magnesia-containing orthophosphate invert glasses were successfully prepared in our earlier work. Orthophosphate groups in the glasses were cross-linked by tetrahedral niobia (NbO4) and magnesia.

Objective: The aim of this work is to prepare calcium orthophosphate invert glasses containing magnesia and niobia, incorporating silica, and to evaluate their structures and releasing behaviors.

The antihistamine olopatadine regulates T cell activation in palladium allergy.

Because of its corrosion resistance palladium (Pd) has been widely used in many consumer products ranging from fashion accessories to dental materials. Recently, however, an increase in Pd allergy cases has been reported. Metal allergy is categorized as a Type IV allergy, which is characterized as a delayed-type hypersensitivity reaction in which T cells are known to play an important role; however, the precise mechanism of their action remains unclear.

Fabrication of low-cost beta-type Ti-Mn alloys for biomedical applications by metal injection molding process and their mechanical properties.

Titanium and its alloys are suitable for biomedical applications owing to their good mechanical properties and biocompatibility. Beta-type Ti-Mn alloys (8-17 mass% Mn) were fabricated by metal injection molding (MIM) as a potential low cost material for use in biomedical applications. The microstructures and mechanical properties of the alloys were evaluated.

Microstructural evolution and mechanical properties of biomedical Co-Cr-Mo alloy subjected to high-pressure torsion.

The effects of severe plastic deformation through high-pressure torsion (HPT) on the microstructure and tensile properties of a biomedical Co-Cr-Mo (CCM) alloy were investigated. The microstructure was examined as a function of torsional rotation number, N and equivalent strain, εeq in the HPT processing. Electron backscatter diffraction analysis (EBSD) shows that a strain-induced martensitic transformation occurs by the HPT processing.

Microstructures, mechanical properties and cytotoxicity of low cost beta Ti-Mn alloys for biomedical applications.

Unlabelled: The microstructures, mechanical properties and biocompatibility of low cost β-type Ti-(6-18)Mn alloys were investigated after solution treatment. Ti-9 Mn exhibits the best combination of tensile strength and elongation among the fabricated alloys, and its performance is comparable to or superior to those of Ti-6Al-4V ELI (Ti-64 ELI) in terms of every parameter evaluated. A hardness of 338 HV, a Young's modulus of 94 GPa, a 0.

Synthesis and characterization of Ag-containing calcium phosphates with various Ca/P ratios.

Ag-containing calcium phosphate (CaP) powders were synthesized by a precipitation method using aqueous solutions of calcium nitrate, silver nitrate, and ammonium phosphate. The powders were sintered at temperatures ranging from 1173 to 1473 K. The charged atomic ratios of (Ca+Ag)/P and Ag/(Ca+Ag) in solution were varied from 1.

Evaluation of thin amorphous calcium phosphate coatings on titanium dental implants deposited using magnetron sputtering.

Objective: Calcium phosphate is used for dental material because of its biocompatibility and osteoconductivity. Amorphous calcium phosphate (ACP) coatings deposited by magnetron sputtering can control their thickness and absorbability. This study aimed to evaluate and characterize ACP coatings deposited via magnetron sputtering.

NKG2D⁺ IFN-γ⁺ CD8⁺ T cells are responsible for palladium allergy.

Nickel, cobalt, and chromium are well known to be causal agents of allergic contact dermatitis. Palladium (Pd) can also cause allergic disease and exposure results from wide use of this metal in dental restorations and jewelry. Metal allergy is categorized as a delayed-type hypersensitivity, and metal-responsive T cell clones have been isolated from allergic patients.

Effects of niobium ions released from calcium phosphate invert glasses containing Nb2O5 on osteoblast-like cell functions.

The effects of niobium ions released from 60CaO-30P(2)O(5)-(10-x)Na(2)O-xNb(2)O(5) (mol %, x = 0-10) glasses on MC3T3-E1 cell functions were evaluated by culture tests with two systems; cell culture on glass plates, or in culture media containing glass extracts. Alkaline phosphatase (ALP) activity in the cells cultured on the glass plates containing 3 and 5 mol % of Nb(2)O(5) was significantly higher than that on the Nb(2)O(5)-free glass, although proliferation was not enhanced on all glasses containing Nb(2)O(5). Cells cultured in the medium containing 3 × 10(-7) M niobium ions showed the highest ALP activity in comparison with other Nb-containing media or normal medium, regardless of the presence of osteogenic factors (ascorbic acid, β-glycerophosphate and dexamethasone) in the media.

Enhancement of nickel elution by lipopolysaccharide-induced inflammation.

Background: Implantations of metallic biomedical devices into bodies are increasing. The elution of Ni ions from these devices can lead to metal allergies. However, the molecular mechanisms of the elution have not been fully examined.

Microscopic observations and inflammatory cytokine productions of human macrophage phagocytising submicron titanium particles.

This study was performed to microscopically observe and measure inflammatory cytokine production by human macrophages phagocytosing submicron titanium (Ti) particles. Observations with secondary electron microscopy (SEM), SEM/electron probe microanalysis (EPMA) and transmission electron microscopy (TEM) indicated that macrophages [phorbol-12-myristate-13-acetate (PMA)-differentiated THP-1 cells] at 24 h in culture actively phagocytosed and accumulated submicron Ti particles in intracellular phagosomes, in which refinement of Ti particles occurred. The macrophages were also cultured for 24 h in four media with and without submicron Ti particles and lipopolysaccharide (LPS; components of bacteria).

Gene expression analyses of human macrophage phagocytizing sub-micro titanium particles by allergy DNA chip (Genopal).

The purpose of this study was to examine gene expressions of macrophage phagocytizing sub-micro Ti particles by a DNA chip. Human monocytic cell line THP-1 was differentiated into macrophages by culturing for two days in medium supplemented with 200 nM phorbol ester (PMA). The macrophages were then cultured in four media: medium without PMA (control); medium with suspended sub-micro Ti particles (0.

Fabrication of calcium phosphate films for coating on titanium substrates heated up to 773 K by RF magnetron sputtering and their evaluations.

Calcium phosphate films were fabricated on titanium substrates heated up to 773 K using radiofrequency (RF) magnetron sputtering. The deposition rate, phase and preferred orientation of the calcium phosphate films were studied. Immersion tests for the films were conducted using Hanks' solution and PBS(-), and the surface reactions on the specimens coated with the calcium phosphate films were investigated.