Papers by Keyword: Simulated Body Fluid (SBF)

Abstract: Bonelike apatite formation abilities of β-tricalcium phosphate (β-TCP) and hydroxyapatite (HA) were enhanced by a simple and useful method of autoclaving in distilled water. By immersion tests using simulated body fluid, the apatite formation was observed on the surfaces of the autoclaved β-TCP and HA after 10 days and confirmed to be controllable by the autoclaving temperature, although the formation was not or dispersedly observed on non-autoclaved samples. Surface potentials and morphologies of the samples were decreased and roughed after the autoclaving

Abstract: Three-dimensionally ordered materials containing hydroxyapatite (HAp) as well as Bioglass® (BG) have been prepared in form of pellets and have been examined the effects of BG addition -in combination with a heat treatment process- on biological properties of composite HAp/BG. The investigation of the bioactive behavior of sintered and unheated biphasic mixtures and the deviations from pure HAp was performed by FTIR spectroscopy and Differential Thermal Analysis. It was observed the appearance of new phases on sintered composite pellets, while a faster biological HAp layer formation was detected, on the composite unheated pellets’ surface than on pure HAp and sintered composite pellets, currently leading to increased bioactivity.

Abstract: Sulfonic groups (-SO3H) were covalently attached on different polymeric surfaces enabling them to induce apatite nucleation, for developing bioactive apatite-polymer composites with a bonelike 3-dimensional structure. High molecular weight polyethylene (HMWPE) and ethylene-co-vinyl alcohol co-polymer (EVOH) were used. The polymers were soaked in two types of sulphate-containing solutions with different concentrations, sulphuric acid (H2SO4) and chlorosulfonic acid (ClSO3H). To incorporate calcium ions into to the sulfonated polymers, the samples were soaked in a saturated Ca(OH)2 solution for 24 hours. After soaking of the samples in a simulated body fluid (SBF), formation of an apatite layer on both surfaces was observed. The results obtained prove the validity of the proposed concept and show that the -SO3H groups are effective on inducing apatite nucleation on the surface of these polymers.

Abstract: Ti and Ti based alloys are characterised by a continuous electrochemical monitoring and a rapid straining electrode technique in simulated body fluid environment. Materials examined are Ti, Ti-6Al-7Nb, Ti-6Al-4V and Ti-29Nb-13Ta-4.6Zr. Sterilized specimens were immersed in Hanks solution or Eagle’s minimum essential medium (MEM) solution. Electrode potential and polarization resistance were simultaneously and continuously measured up to 7 days. For all the specimens examined, the corrosion potential reached to a steady state in 2 days for both solutions. On the other hand, corrosion resistance increased monotonously for the period examined. Tensile specimens were rapidly elongated under potentio-static polarization to evaluate the transient current after exposure of newly-created surface. The anodic current appeared during both elastic and plastic deformation. For Ti alloys, anodic current started to increase gradually during elastic deformation, then increased more rapidly to reveal a maximum when straining was stopped, then decreased. Pure Ti, on the other hand, revealed the transient current after plastic deformation, but does not show any current increase during elastic deformation. The larger dissolution for a straining was observed as the following order; Ti, Ti-29Nb-13Ta-4.6Zr, Ti-6Al-7Nb, then Ti-6Al-4V.

Abstract: The bioactivity of Ti6Al4V induced by SSPB (supersonic particles bombarding) and alkali treatment was investigated in this work. More coarse surfaces were formed by SSPB and alkali treatment, which led to better bioactivity than that by only alkali treatment. Apatite began to appear on the surface of specimen only after 1 day of immersion in 1.5 SBF. As time passed, they gradually covered the whole surfaces. After 7 days of soaking in vitro, apatite formed and covered all the surfaces of the titanium alloys, and they packed very densely and uniformly. EDS and XRD results proved all the new-formed phases were composed of a carbonate containing hydroxyapatite with small crystallites and defective structure. As a result, SSPB treatment might be an effective way to enhance the bioactivity of titanium alloys for implantation.

Abstract: TiO2 coatings on titanium alloy substrates were prepared by atmospheric plasma spraying using commercial nano-powders. Then, as-sprayed coatings were treated using 10% hydrofluoric acid (HF) at room temperature for 30 seconds. As-sprayed and HF-treated titania coatings were soaked in simulated body fluid to investigate the formation of apatite on their surface. Field-emission scanning electron microscopy was used to observe the surface morphologies, and the phase composition of the as-sprayed coating and apatite were analyzed by X-ray diffraction and energy-dispersive X-ray spectrometry. As-sprayed titania coating is composed of rutile, anatase, and a small quantity of Ti3O5. It exhibited excellent adhesion between the TiO2 coatings and titanium alloy substrates, and the bonding strength was about 38 MPa. After in vitro experiment, a new substance containing calcium and phosphate was formed on the surface of HF-treated TiO2 coatings after being soaked in SBF, while the new substance was not formed on the surface of as-sprayed TiO2 coatings. The results indicated that the bioactivity can be induced to the surface of plasma sprayed TiO2 coatings by hydrofluoric acid treatment.

Abstract: A titanium base alloy and a cobalt base alloy have been subjected to a biomimetic process. Samples of titanium and cobalt alloys have been immersed in 10M and 5M NaOH solutions, respectively, then the samples have been heat treated and finally, immersed in either a simulated body fluid (SBF) with ionic concentration close to human blood plasma or in a simulated body fluid with an ionic concentration 1.5 times that of the SBF (1.5SBF) for a period of 21 days. An apatite layer has been observed after the immersion of the samples in SBF for both Ti and Co base alloys. The apatite layer observed on the Ti alloy samples is more homogeneous and thicker than that observed on the Co alloy samples. However, the apatite layer on both samples is not continuous and homogeneous along the surface. The layer of apatite formed is thicker on samples immersed in 1.5SBF. This is attributed to the higher ion concentrations, mainly of calcium and phosphorus. The Ca/P ratios measured in the apatite layers are close to that of bone.

Abstract: Zirconia-alumina composites with additions of a CaO-SiO2 glass are prepared by uniaxial pressing and sintering. In order to promote bioactivity, the composites are biomimetically treated. The effect of immersion time in simulated body fluids (SBF) and that of the presence of a wollastonite powder bed, as a calcium ion provider, on the apatite forming ability are investigated. The influence of replacing the simulated body fluids each 7-day-period for a more concentrated solution is also studied. A bonelike apatite layer is observed after 21 days of immersion when the SBF is renewed, whether the bed of wollastonite powder is present or not. However, a thicker layer is formed by using wollastonite and the agglomerates of the apatite layer are finer on the composites containing CaO-SiO2 glass.

Abstract: Biphasic calcium phosphate (BCP) ceramics, a mixture of hydroxyapatite (HAp) and beta-tricalcium phosphate (β-TCP), of varying HAp/β-TCP ratios were prepared from fine powders. Porous BCP ceramic materials with HAp/β-TCP weight rations of 20/80, 40/60, and 80/20 were prepared. In this study, the bioactivity is reduced at a bigger HAp content rate, which is likely related to the high driving pore for the formation of a new phase, and the reaction rate was proportional to the β-TCP. The porous BCP ceramics having a bigger porosity rate can easily under up dissolution. The powder having a bigger β-TCP content rate can easily generate a new phase. The dissolution results confirmed that the biodegradation of calcium phosphate ceramics could be controlled by simply adjusting the amount of HAp or β-TCP in the ceramics and porosity rate.

Abstract: Hydroxyapatite (HA) powders were directly synthesized in simulated body fluid (SBF) at 37°C, without the need for high-temperature calcified. These powders were found to contain trace amount of CO32-, Cl-, Na+ and K+ impurities, originated from the of SBF solutions during their deposition. The characterizations of the synthesized HA powders were performed by X-ray diffraction (XRD), Fourier-transformed infra-red spectroscopy (FTIR) and Transmission electron microscope (TEM). The experimental results showed that the HA synthesized by the SBF route might be more close to that human bone in structure and compositions. Furthermore, the processes flow for HA synthesis was optimized and the synthesized mechanism was also discussed.