Key Engineering Materials Vols. 330-332

Abstract: Biomimetic coating on roughed titanium plates were prepared in this work by a cathode deposition method in calcium phosphate solution electrolyte. The coatings of plate-like apatite crystals were deposited on the titanium plates under a constant potential of 2.0V for 60 min at 37. The coating crystals were identified to be carbonate-containing apatite (bone-like apatite) by X-ray diffraction and scanning electronic microscopy. The cell proliferation and adhesion of L929 cells on the titanium metal plates with biomimetic coating and the titanium plates with roughed-only were tested. The results showed that biomimetic coating on titanium surface can enhance the materials bioactivity. The study indicated that cathode method is potential to prepare biomimetic coating on titanium implants with excellent bioactivity.

Abstract: DNA transfection by biomaterial is a promising strategy to stimulate cells in tissue engineering. Co-precipitation of Calcium Phosphate (CaP) with plasmid DNA (pDNA) is known for several decades as non-viral transfection agent [1]. In this study, we report the co-precipitation of different pDNA into biomimetic calcium phosphate coating onto titanium alloy (Ti) plates in order to evaluate their efficiency of incorporation. And it is possible to tune the rate of coprecipitation by changing the volume of Calcium Phosphate Solution (CPS) and the [pDNA]. The structure of coating was affected by the presence of DNA in CPS solution.

Abstract: Hydroxyapatite(HAP) has excellent osteoconductive properties. By controlling the Ca/P ratio better biphasic calcium phosphate ceramics can be produced than pure HAP ceramics. β- calcium pyrophosphate(β-Ca2P2O7) is a new biodegradable ceramic material and its biological response is quite similar to HAP. Obtaining HAP and other bioactive calcium phosphate ceramic coatings has been a popular research field in the past. In our research a new bioceramic composite coating was obtained by laser cladding with pre-depositing mixed powders of CaHPO4·2H2O and CaCO3 directly on the metal substrate. Its main constituents are HAP and β-Ca2P2O7. The microstructure of the coating consists of minute granular HAP that is distributed among the overlapped club-shaped or needle-like β-Ca2P2O7. The hardness distribution in the cladding layer is even and its value is much higher than that in the substrate. There is a bonded structure of the epitaxial planar growth between the substrate and cladding layer, and both a typical cellular microstructure in the middle and an equiaxed microstructure at the top of the cladding layer.

Abstract: Titanium oxide films were obtained by MAO at the applied voltages of 250-550V and their bio-mineralization behavior was investigated. The films were composed mainly of TiO2 phases in the form of anatase and rutile and enriched with Ca and P elements in the form of CaTiO3 and amorphous calcium phosphate. Their bio-mineralization behavior was evaluated in a simulated body fluid (SBF). After immersed in SBF for 72 h, white mineralized layers were observed on the samples obtained at high voltages. The bio-mineralized rate of samples increased with the applied voltages, which resulted in the difference on morphology of different samples. The structure and composition of the films have an important effect on their bio-mineralization behavior.

Abstract: Titania films were coated by means of sol-gel method on various substrates such as titanium, titanium alloy, silicon wafer, stainless-steel, alumina, and glass slide where they coded as C5Ti, C5Ti6Al4V, C5Si, C5SUS, C5Al2O3 and C5GS, respectively. Their in vitro apatite-forming ability was examined with the Kokubo’s simulated body fluid (SBF; pH 7.4, 36.5°C). C5Ti, C5Ti6Al4V and C5Si deposited apatite particles on their surface within 7 days, whereas, C5SUS, C5Al2O3 and C5GS did not. These results implied that the in vitro apatite-forming ability of the titania films indirectly depended on the chemical or physical properties of the substrates.

Abstract: After the Tantalum metal was subjected to the anodic oxidation at suitable voltage in 2M H2SO4 solution, tantalum oxide with rhombic or amorphous structure formed on the metal surface. The Oxide showed apatite formation ability in simulative body fluid at 6d. It meant the anodic oxidation treatment ia an effective method to accelerate the bioactivity of tantalum metal.

Abstract: Revised simulated body fluid (rSBF) was prepared using a conventional route but all the chemicals were dissolved in commercial cow milk instead of de-ionized water. To accelerate crystallization and increase the amount of precipitates, the influence of milk on the crystallization of calcium phosphates was studied in supersaturated solutions equal to 4 times the ionic concentrations of rSBF. The experiments were carried out in physiological conditions, i.e. pH of 7.35–7.40, temperature of 37.0 (± 0.2) °C, and duration of 7 days, using a constant-composition double-diffusion (CCDD) device, which enables slow precipitation in strictly controlled crystallization conditions. Similar experiments with 4 times the ionic concentrations of rSBF using de-ionized water as solvent were carried out as control. For comparison purposes, another set of experiments with 4 times the ionic concentrations of rSBF in de-ionized water also containing 40 g of bovine serum albumin (BSA) per liter was also conducted. The experimental results showed that the behavior of milk was similar to the presence of dissolved BSA. Some components of milk, presumably proteins, co-precipitated with calcium phosphates. This phenomenon had a strong negative influence on the crystallinity of the precipitates.

Abstract: The ultra-thin film composed of chitosan (CS) and sulfated chitosan (SCS) was assembled on the titanium oxide surface by layer-by-layer (LBL) self-assembly methods. The titanium oxide film was treated by NaOH solution, followed by successively dipping the substrates in 5mg/ml sulfated chitosan (SCS) and 5mg/ml chitosan (CS) solutions alternatively, We hypothesized that this biologic coating may have the property of good biocompatibility, antibacteriostatic effect, anticoagulant activitves and enhancing sell biocompatibility.

Abstract: In the present work, thin films of hydroxyapatite (HAp), titanium, and hydroxyapatite doped with different titanium concentrations were obtained by sputtering and characterized using several analytical techniques. These films are intended to be used as model surfaces on protein adsorption studies in order to better understand the role of titanium ions in biological processes.