Papers by Keyword: Bone-Like Apatite

Abstract: When the pH or the temperature of a simulated body fluid (SBF) is raised, fine particles of calcium phosphate are precipitated. We found that this particle actively induces apatite formation in body fluid or SBF and named it Apatite Nucleus (AN). In this study, we fabricated bone-like apatite self-supporting thin film by biomimetic method using AN. We analyzed it by FE-SEM, EDX, TF-XRD and ICP. It was found that the film has similar crystallinity and Ca/P ratio to those of biological apatite and ca. 10 μm of thickness.

Abstract: Bone tissue engineering provides a new way to repair the bone defect in orthopaedics. The scaffolds, porous materials with excellent biocompatibility, bioactivity and biodegradability, play an important role in bone tissue engineering. Furthermore, the bioactivity of the pore interior surfaces is very important for cell attachment, differentiation and growth, as well as new bone tissue ingrowth into pores. In this paper, β-TCP was selected as materials of scaffolds, and its bioactivity was improved by activating the interior surfaces of pore walls. The porous β-TCP scaffolds with about 50~300μm of pore size and above 80% of porosity were obtained by 3D-gel-laminated processing. Their surfaces of the scaffolds were easily covered by a low crystallized bone-like apatite layer, which determined by XRD and FTIR, after immersing in 1.5SBF solution following pre-treatment by NaOH solution. MTT and ALP assays were performed after cells cultured on the porous scaffolds with bone-like structure, and the results showed higher proliferation rate and differentiation level than that on the scaffolds without treatment, which indicated that the porous β-TCP scaffolds with bone-like apatite layer on surfaces of pore walls possess higher bioactivity. Therefore, the bioactivity of tissue engineering scaffolds could be improved by deposited bone-like apatite layer on their surfaces.

Abstract: Basic drawbacks of calcium phosphate cements (CPCs) are the brittleness and low strength behavior which prohibit their use in many stress-bearing locations, unsupported defects, or reconstruction of thin bones. Recently, to solve these problems, researchers investigated the incorporation of fibers into CPCs to improve their strength. In the present study, various amounts of a highly bioactive glass fiber were incorporated into calcium phosphate bone cement. The obtained results showed that the compressive strength of the set cements without any fibers optimally increased by further addition of the fiber phase. Also, both the work-of-fracture and elastic modulus of the cement were considerably increased after applying the fibers in the cement composition. Herein, with the aim of using the reinforced-CPC as appropriate bone filler, the prepared sample was evaluated in vitro using simulated body fluid (SBF) and osteoblast cells. The samples showed significant enhancement in bioactivity within few days of immersion in SBF solution. Also, in vitro experiments with osteoblast cells indicated an appropriate penetration of the cells, and also the continuous increase in cell aggregation on the samples during the incubation time demonstrated the ability of the reinforced-CPC to support cell growth. Therefore, we concluded that this filler and strong reinforced-CPC may be beneficial to be used as bone fillers in surgical sites that are not freely accessible by open surgery or when using minimally invasive techniques.

Abstract: Bioactive ceramics such as bioactive glasses, calcium carbonate and sintered hydroxyapatite are widely used in biomaterials field because of their high biocompatibility. In this study, natural hydroxyapatite (N-HA) and synthetic Hydroxyapatite (S-HA) were heat treated at 800°C and studied using “in vitro” experiments. Several physicochemical methods like: SRD, FTIR, SEM and ICP-OES were employed to evaluate the effects of the thermal treatment and to compare their behaviour after soaking in the Simulated Body Fluid SBF at different times. The formation of TCP has favours the formation of new phase. Obtained results show that the dissolution occurred more in N-HA than in S-HA and consequently the precipitation of new phosphate phase is more important in N-HA. This is due to the presence of Mg, Sr and Zn in N-HA with concentration higher to that in S-HA.

Abstract: Porous β-TCP scaffold was prepared using three-dimensional gel-lamination technology with foamy slurry. Then the sintered scaffolds were soaked in 1.5SBF solution to achieve scaffolds with bone-like structure. After soaking, a low crystallized bone-like apatite layer containing CO3 -2 was formed on the surface of the scaffold. With presoaking in NaOH solution, the formation of the bone-like apatite layer on the surface of the scaffold in 1.5SBF solution was accelerated. In this way, a bioactive porous β-TCP scaffold with bone-like structure could be prepared.

Abstract: In order to improve the bioactivity of calcium phosphate bioceramics, biphasic HA/β-TCP (BCP) bioceramics were prepared by the microwave sintering and the microwave plasma sintering. Bone-like apatite formation of the resulting samples was investigated in simulated body fluid (SBF). The samples were also implanted in dorsal muscles of healthy dogs for 1.5and 3 months. All samples after taking out were examined by histological observation. Bone formation in different sintering ways and temperatures was investigated in details. Better osteoinductivity was found in samples sintered by the microwave and microwave plasma instead of the conventional furnace, as well as by lower temperature (1050 oC) instead of higher temperature (1150 oC). It accounts for that the increase in degradability of materials sintered by microwave and microwave plasma or lower temperature leads to the better of bone-like apatite formation and bone formation due to fine grains and lower crystallinity.

Abstract: BGC, HA, β-TCP and biphase calcium phosphate (β-TCP/HA) were modified by using the cold plasma technique in the present study. The study results came from the formation of bone-like apatite in SBF and results of osteoblast culture in vitro, SEM, XPS, and XRD. The results showed that the formation of bone-like apatite on bioceramics modified by cold plasma was easier than that of no modification and the growth of osteoblast could be promoted. The active mechanism was that impact on bioceramics by means of the particles with high energy and high activity led to rough and etched surface of bioceramics, as well as the distortion of bioceramics crystal, which increased solubility of materials and local concentration of Ca and P ion. It was helpful for the formation of bone-like apatite. It was showed that the modification using cold plasma technique could increase the activity of bioceramics.

Abstract: The PCL plates hydrolyzed by NaOH aqueous solutions and carboxylate groups were introduced onto the surfaces of specimen. Specimens were treated by CaCl2 and K2HPO4⋅3H2O under the normal-pressure condition and low-pressure of 103 Pa condition for 30min separately. Dense and uniform bone-like layers could be formed on the surface of specimens after mineralizing for less than 24h in simulated body fluids (SBF). The low-pressure condition could accelerate the formation of apatite layer.

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.