Titanium In Simulated Body Fluid Research Articles

Study on the Effect of a Surface Roughness on the Osteoconductivity of Bio-active Titanium in Simulated Body Fluid

Study on the Effect of a Surface Roughness on the Osteoconductivity of Bio-active Titanium in Simulated Body Fluid

Calcium Phosphate Formation on Titanium and Zirconium and Its Application to Medical Devices

Titanium and zirconium were immersed in Hanks’ solution with and without calcium and phosphate ions, and the surfaces were characterized with X-ray photoelectron spectroscopy (XPS) to determine the mechanism of calcium phosphate formation on titanium in simulated body fluids and in a living body. In addition, they were cathodically polarized in the above solutions. As a result, neither calcium nor phosphate stably exists alone on titanium, and calcium phosphate is naturally formed on it; calcium phosphate formed on titanium is stable and protective. On the other hand, calcium is never incorporated on zirconium, while zirconium phosphate, which is easily formed on zirconium, is highly stable and protective.

Difference in surface reactions between titanium and zirconium in Hanks' solution to elucidate mechanism of calcium phosphate formation on titanium using XPS and cathodic polarization

Titanium and zirconium were immersed in Hanks' solution with and without calcium and phosphate ions, and the surfaces were characterized with X-ray photoelectron spectroscopy (XPS) to determine the mechanism of calcium phosphate formation on titanium in simulated body fluids and in a living body. In addition, they were cathodically polarized in the above solutions. XPS characterization and cathodic polarization revealed differences in the surface properties in the ability of calcium phosphate formation between titanium and zirconium. The surface oxide film on titanium is not completely oxidized and is relatively reactive; that on zirconium is more passive and protective than that on titanium. Neither calcium nor phosphate stably exists alone on titanium, and calcium phosphate is naturally formed on it; calcium phosphate formed on titanium is stable and protective. On the other hand, calcium is never incorporated on zirconium, while zirconium phosphate, which is easily formed on zirconium, is highly stable and protective. Our study presents new information regarding the surface property of titanium and demonstrates that the characteristics of titanium and zirconium may be applied to various medical devices and new surface modification techniques.

Development of Bioactive Titanium-Apatite Nuclei Composite

Apatite nuclei were precipitated in the pores of titanium in simulated body fluid (SBF) and titanium-apatite nuclei composite was obtained. Apatite was induced by the apatite nuclei inside the pores of the composite and apatite layer was formed on the composite surface by soaking in SBF. The apatite layer showed high adhesive strength to the composite due to a mechanical interlocking effect between the composite and the apatite.

Corrosion behavior of micro-arc oxidation film on titanium in simulated body fluid

To investigate the variation of the corrosion resistance of micro-arc oxidation film on titanium by electrochemical methods in simulated body fluid. Micro-arc oxidation film was formed on the titanium surface using micro-arc oxidation. The morphology was observed with scanning electron microscopy (SEM) and the phase composition was analyzed using X-ray diffraction (XRD). Polarization curves and electrochemical impedance spectroscopy (EIS) in simulated body fluid were examined with electrochemical methods. On the titanium surface with micro-arc oxidation, the film consisted of many volcanic micropores. The film formed was a titanium dioxide (TiO(2)) with peaks for both anatase and rutile phases. In addition, hydroxylapatite was also observed. The self-corrosion potential and self-corrosion current density of titanium with micro-arc oxidation film were -0.255 V and 0.80 microA/cm(2) respectively, while those of untreated titanium were -0.358 V and 0.55 microA/cm(2). Electrochemical impedance spectroscopy confirmed the model of equivalent circuits reasonable. The results of electrochemical examinations indicate that micro-arc oxidation film increases the corrosion resistance of titanium.

Bioactive layer formation on alkaline-acid treated titanium in simulated body fluid

Porous surface on titanium induces apatite formation in simulated body fluid (SBF). This work shows alkaline, acid and polishing treatment, which lead to create apatite coating. Specimens were soaked in 5 M solution of NaOH, 85% HCl–6% HF–9% H 3PO 4 and 2% HF–4% HNO 3–94% H 2O. Also many samples were polished with sandpaper. Specimens treated under the above conditions were soaked in simulated body fluid (SBF) for 5 days. Apatite formed within 5 days. The evaluation of Ca/P ratio of samples were made by EDAX analysis to get information of the Ca/P ratio. The values obtained for the apatite were in the range of 1.55, which is near to the stoichiometric value of apatite, for the sample, which was treated in mixed solution of HCl–HF–H 3PO 4.

Apatite-forming ability of micro-arc plasma oxidized layer of titanium in simulated body fluids

Micro-arc plasma oxidation (MAO) in sulfuric acid was performed to induce apatite-forming ability of the titanium surface. After MAO treatment, the specimens were immersed in a simulated body fluid (SBF) or modified SBFs that had higher pH, calcium and phosphorus concentration than SBF to investigate apatite formation on their surfaces. Immersing in the conventional SBF at 36.5 °C, the specimen showed low ability of apatite formation on the surface, while immersion in the modified SBFs showed higher potential of the apatite formation on the MAO surface than mere Ti surface. This indicates that the MAO treatment leads a potential of bioactivity, i.e. osteoconduction, on titanium substrates.

Photoexcited formation of bone apatite‐like coatings on micro‐arc oxidized titanium

A novel method to rapidly deposit bone apatite-like coatings on titanium implants in simulated body fluid (SBF) is proposed in this article. The processing was composed of two steps; for example, micro-arc oxidation (MAO) of titanium to form titania films, and UV-light illumination of the titania-coated titanium in SBF. The morphology, crystalline structure, and bond strength of the MAO films were investigated as a function of the applied voltage (in the range of 250-400 V) by using scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectrometry, Fourier transform infrared spectroscopy, adhesion-tensile test, and scratch test. Results showed that the MAO films were porous and nanocrystalline with pore sizes varying from 1 to 3 microm and grain sizes varying from 10-20 to 70-80 nm; the predominant phase in titania films changed from anatase to rutile, and the bond strength of the films decreased from 43.4 to 32.9 MPa as the applied voltage increased from 250 to 400 V. After UV-light illumination of the films in SBF for 2 h, bone apatite-like coating was deposited on the MAO film formed at 250 V. The bond strength of the apatite/titania bilayer was about 44.2 MPa. However, no apatite was observed on the MAO film formed at 400 V after UV-light illumination.

Apatite deposition on thermally and anodically oxidized titanium surfaces in a simulated body fluid

By application of a special specimen set-up, thermally oxidized titanium specimen pairs were found able to deposit apatite on the contact surfaces after soaking for 7 days in the simulated body fluid (SBF) of Kokubo's recipe. The specimens oxidized at 400°C and 500°C showed the highest ability of apatite deposition. Both increase and decrease in oxidation temperature from this range caused the apatite deposition ability to decrease. The specimen without treatment failed to deposit any apatite. Specimens anodically oxidized in electrolytes of H 3PO 4, H 2SO 4 and acetic acid exhibited very low ability of apatite deposition. Furthermore, the specimen thermally oxidized at 400°C was even able to help the surfaces of PTFE and silicone deposit apatite in the PTFE–Ti and silicone–Ti pairs. This in vitro experimental results indicated that the difference in apatite deposition among various titanium oxides does exist and can be distinguished by applying the present specimen set-up. The mechanism of the apatite deposition on the contact surfaces was discussed in relation to the passive dissolution of titanium in SBF. The release of titanium hydroxide and OH − ions from the titanium surfaces and their accumulation inside the confined space between the two contact surfaces were suggested to be responsible for the apatite deposition.

Growth of bioactive surfaces on titanium and its alloys for orthopaedic and dental implants

A simple chemical method was established for inducing bioactivity of titanium and its alloys. Recently, T. Kokubo demonstrated that an in vitro chemical-deposited bone-like apatite on Ti with bone-bonding ability could be induced. Following treatment, a dense bone-like apatite layer is formed on the surface of the titanium in simulated body fluid (SBF). Observation of the samples in wet state by means of the environmental scanning electron microscope (ESEM) enabled us to observe the calcium phosphate deposition process in situ over a number of days. One of the most important features of the study is that it was carried out on a single, unchanged titanium sample and the process was not at any stage interrupted. Moreover, it was demonstrated that human osteoblast adhesion and differentiation behaviour are better in bioactive titanium than in the titanium without the chemical treatment.

Growth of bioactive surfaces on dental implants.

Some metallic materials, such as pure titanium, Ti-6Al-4V, are used for dental and orthopedic implants under load-bearing conditions. However, they do not form a chemical bond with bone, which would achieve a good implant-bone fixation in service. In recent works, it has been demonstrated that an in vitro, chemically deposited, bone-like apatite layer with bone-bonding ability could be induced on a titanium surface. By reproducing that chemical procedure, in this work, a dense bone-like apatite layer was formed on the surface of the titanium in simulated body fluid. In addition, the different steps and kinetics of the layer-formation have been studied, because the observation of the samples in the wet state by means of the environmental scanning electron microscope has allowed the observation in situ of the apatite deposition process over a number of days. One of the most important features of the present study is that it can be carried out on a single titanium sample and the process is not interrupted at any stage. One of the main drawbacks of this chemical method is that the samples covered with apatite are susceptible to contamination by bacteria. The behavior of different types of antibiotics used to avoid this contamination has also been studied using the environmental scanning electron microscope. Finally, osteoblast cells have been cultured on the apatite-coated titanium samples to assess their biocompatibility.

Bioactive titanium: effect of sodium removal on the bone-bonding ability of bioactive titanium prepared by alkali and heat treatment.

As reported previously, bioactive titanium is prepared by simple alkali and heat treatment, and can bond to living bone directly. The purpose of this study was to accelerate the bioactivity of bioactive titanium in vivo. In in vitro study, sodium removal by hot water immersion enhanced the apatite-forming ability of bioactive titanium in simulated body fluid dramatically. The specific anatase structure of titania gel was effective for apatite formation in vitro. In the current study, we investigated the in vivo effect of sodium removal on the bone-bonding strength of bioactive titanium. Sodium-free bioactive titanium plates were prepared by immersion in an aqueous solution of 5 M NaOH at 60 degrees C for 24 h, followed by immersion in distilled water at 40 degrees C for 48 h before heating them at 600 degrees C for 1 h. Three kinds of titanium plates were inserted into rabbit tibiae, including untreated cp-Ti, conventional alkali- and heat-treated Ti, and sodium-free alkali- and heat-treated Ti. In vivo bioactive performance was examined mechanically and histologically after 4, 8, 16, and 24 weeks. Sodium removal enhanced the bone-bonding strength of bioactive titanium at 4 and 8 weeks postoperatively; however, its bone-bonding strength was inferior to that of conventional alkali- and heat-treated titanium at 16 and 24 weeks. Histological examinations after the detaching test revealed breakage of the treated layer in the sodium-free alkali- and heat-treated titanium group. In conclusion, sodium removal accelerated the in vivo bioactivity of bioactive titanium and achieved faster bone-bonding because of its anatase surface structure, but the loss of the surface's graded structure due to the complete removal of sodium decreased the adhesive strength of the treated layer to the titanium substrate. Further investigations are required to determine the optimum conditions for preparation of bioactive titanium.

Corrosion behaviour of nitrogen implanted titanium in simulated body fluid

AbstractTitanium is one of the most important materials for medical applications, as a result of its uniquely high biocompatibility. The effect of nitrogen implantation on the biocompatibility and the corrosion resistance of cp titanium are reported. Grazing incidence X-ray diffraction studies showed that implantation formed a δ-TiNx phase. Electrochemical tests in HBSS showed an optimal decrease in corrosion current density for specimens implanted with 3 × 1017 ions cm-2 at 25 keV, compared with unimplanted titanium. Following implantation and immersion in a commercial physiological solution, phases are precipitated which are rich in calcium and phosphorus, and these hydroxyapatite precursors indicate that this implantation regime confers optimal properties of corrosion resistance and biocompatibility.

In vitro corrosion evaluation of nitrogen ion implanted titanium in simulated body fluid

Surface modification of commercially pure (CP) titanium was attempted by nitrogen ion implantation to investigate corrosion resistance in simulated body fluid. Nitrogen ion was implanted at 70 keV energy for different doses ranging from 5 × 1015 to 2.5 × 1017 ions/cm2. In Vitro Open Circuit Potential (OCP-time measurements and cyclic polarization studies were carried out to evaluate the corrosion resistance of the implanted specimens with reference to the unimplanted one. Specimens implanted at 4 × 1016 and 7 × 1016 ions/cm2 showed optimum corrosion resistance, and implantation beyond this dose deteriorated the corrosion resistance. Gracing Incidence X-ray diffraction (GIXD) was employed on implanted specimens to understand the phases formed with increasing doses. The results of the present investigation indicated that nitrogen ion implantation can be used as a viable method for improving corrosion resistance of titanium. Nature of the surface and reason for the variation and improvement in corrosion resistance are discussed in detail. In vitro Korrosionsuntersuchung von Stickstoffionen-dotiertem Titan in simulierter Korperflussigkeit Durch Stickstoffionen-Dotierung wurde eine Oberflachenmodifikation von handelsublichem, reinen Titan vorgenommen, um den Korrosionswiderstand in simulierter Korperflussigkeit zu untersuchen. Stickstoffionen wurden bei einer Energie von 70 keV bei unterschiedlichen Dosen von 5 × 1015 bis 2,5 × 1017 Ionen/cm2 eingebracht. In vitro wurde das freie Korrosionspotential in Abhangigkeit von der Zeit bestimmt sowie zyklische Polarisationsmessungen durchgefuhrt, um den Korrosionswiderstand der dotierten Proben im Vergleich zu undotierten Proben zu untersuchen. Proben, die mit 4 × 1016 und 7 × 1016 Ionen/cm2 dotiert wurden, zeigten den besten Korrosionswiderstand, wahrend eine Dotierung oberhalb dieser Dosis den Korrosionswiderstand verschlechterte. Um die bei zunehmender Dosis sich bildenden Phasen zu verstehen, wurden GIXD-Messungen eingesetzt. Die Ergebnisse der vorliegenden Untersuchung zeigen, das die Stickstoffionen-Dotierung als eine realisierbare Methode zur Verbesserung des Korrosionswiderstandes von Titan genutzt werden kann. Die Beschaffenheit der Oberflache und die Grunde fur die Variation und Verbesserung des Korrosionswiderstandes werden ausfuhrlich diskutiert.