Papers by Keyword: Porous Hydroxyapatite

Abstract: This study prepared porous hydroxyapatite (porous HA) as synthetic scaffold and find out chemical properties, porosity, compressive strength and cytotoxicity properties. Porous HA was prepared by powder deposition and sintering from HA-PMMA mixed powder. Porous HA characterizations were conducted by XRD, XRF, SEM-EDX and mercury porosimetry analysis. In vitro cytotoxicity testing of porous HA was conducted by MTT method using vero cells. Porous HA has porosity on the interval 62.79 to 69.67% and compressive strength on the interval 1.53 to 3.71 MPa. Optimal porous HA has porosity is 62.79% with compressive strength is 3.71 MPa. Mercury porosimetry analysis showed that optimal porous HA has interconnective porosity up to 88.25% with pore size on the interval 0.05-355 μm and median pore is 52.64 μm. There was no significantly difference in the death percentage of vero cells caused HA powder and optimal porous HA (p= 0.158) but concentration of optimal porous HA were significantly effect on the percentage of vero cells death (p=0.003).

Abstract: The aim of this study was to evaluate the osteoconductive properties of synthetic porous hydroxyapatite prepared by low-temperature microwave processing OssaBase^® HA (SPHA) in comparison with biological apatite, non-sintered deproteinized bovine bone Bio-Oss^® (DBB). The materials were implanted into the bone sockets of the tibia of Beagle dogs for 3 and 6 months. The bone response to granules of the materials of similar sizes was compared. Histological analysis of the specimens with histomorphometry was performed at different times after in vivo implantation. Based on the histological analysis, the level of bone formation in the spaces between the implanted granules and through the interconnected pores of both implanted materials within a cortical region was significantly higher (bone area ingrowth 72–85%) than within a cancellous bone site (bone area ingrowth 16–28%) at three and six months after implantation. According to our study, the bioactive and osteoconductive properties (bone implant contact and bone area ingrown) of the synthetic porous hydroxyapatite are very high and comparable with the biological apatite, non-sintered deproteinized bovine bone. The favourable influence of the high specific surface area and carbonate content of the synthetic, porous hydroxyapatite on bone formation was confirmed.

Abstract: Porous hydroxyapatite (HA) bioceramic matrix with interconnected ducts was obtained using a porogen burnout technique at 1200°C. The HA/silk fibroin (SF) composite scaffolds were developed with the SF sponges formed inside the pores and ducts of the bioceramics by first introducing HA/SF slurries into the pores and ducts followed by a freeze-drying process. Phase components and morphology of materials were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. Porosity was measured by Archimedean method. Compressive strength was also measured. The simulated body fluids (SBF) experiments were conducted to evaluate bioactivity. The results show that hydroxyapatite is the main phase compositions after sintering at 1200°C. The porosity of composite scaffolds reaches 70%~80%. The sizes of pores and ducts of HA matrix range from 150μm to 400μm and the pore sizes of SF sponges formed inside the macroporous structure of bioceramics are approximately 100μm,a structure favorable for bone tissue in-growth. The compressive strength of the composite scaffolds is greatly improved in comparison with that of HA matrix. In the SBF tests, a layer of randomly oriented apatite crystals form on the scaffold surface after sample immersion in SBF. The cell culture experiments show that the osteoblast cells are attached and proliferated on the surface of the composite scaffold, which suggest good bioactivity and cellular compatibility of the composite material.

Abstract: A porous silicon-containing hydroxyapatite has been prepared using natural coral as a calcium source to obtain a biomaterial having an improved biocompatibility. From the XRD analysis, it was confirmed that the single-phase hydroxyapatite containing silicon has formed without revealing the presence of extra phases related to silicon dioxide or other calcium phosphate species. Silicon content is ranged from 0.5wt% to 1wt% by weight. The porous silicon-containing hydroxyapatite blocks were inserted into the 5mm diameter of drill holes made through the lateral femoral condyles of New Zealand white rabbits. The new bony formation did not begin after 1 week. At 3 week, bony ongrowth to the inserted porous silicon-containing hydroxyapatite block could be found, and the new bone surrounded the inserted block entirely after 24weeks. Based on in-vivo test, Si-containing porous hydroxyapatite derived from coral possesses high biodegradability and can be considered a useful material for bone implants.

Abstract: Porous hydroxyapatite bioceramics were obtained by impregnating the polyurethane sponge with rheologically optimized slurry. 6wt% bioglass was doped into hydroxyapatite to act as a sintering additive. Thermal analysis was used to study the pyrolysis process of the polyurethane sponge. Phase component and surface morphology were characterized by X-ray diffraction and scanning electron microscopy, respectively. It was found that hydroxyapatite was the main phase composition of the porous ceramics sintered at 1250°C. The porous bodies prepared had an open, uniform and interconnected structure with pore size of 200-400μm. The porous ceramics possessed high porosity of 70-80% and compressive strength of 2.3MPa. The precipitates formed on the surface of the porous ceramics might be bone-like apatite after immersion in a simulated body fluid for various periods.

Abstract: Despite extensive efforts in the development of fabrication methods to prepare porous ceramic scaffolds for osseous tissue regeneration, all porous materials have a fundamental limitation- the inherent lack of strength associated with porosity. Shells (nacre), tooth and bone are frequently used as examples for how nature achieves strong and tough materials made out of weak components. So, the unresolved engineering dilemma is how to create a scaffold that is both porous and strong. The objective of this study was to mimic the architecture of natural materials in order to create a new generation of strong hydroxyapatite-based porous scaffolds. The porous inorganic scaffolds were fabricated by the controlled freezing of water-based hydroxyapatite (HA) slurries. The scaffolds obtained by this process have a lamellar architecture that exhibits similarities with the meso- and micro- structure of the inorganic component of nacre. Compressive strengths of 20 MPa were measured for lamellar scaffolds with densities of 32%, significantly better than for the HA with random porosity. In addition, the lamellar materials exhibit gradual fracture unlike conventional porous HA scaffolds. These biomimetic scaffolds could be the basis for a new generation of porous and composite biomaterials.

Abstract: Porous HA ceramics has been developed for the scaffold materials because the porous structure has been recognized to be necessary to invasion of body fluid and ingrowth of bone. The synthesized porous HA ceramics with several porosities were electrically polarized, and then the TSDC spectra were measured. The maximum electric current density and the stored polarization charges decreased with increasing the porosity. Therefore it was thought that the decreasing the amount of proton of porous HA ceramics was one of the reasons of decreasing of the maximum electric current densities and the stored charges. The simulated body fluid (SBF) test implied that electrovector effects enhanced the apatite formabilities.

Abstract: HA has a high affinity for bone as well as various tissues. In the present study, we investigated an affinity for abdominal organs. Coralline hydroxyapatite ceramic (HA, cubic structure 4x4x4mm, Interpore 500) was used in this experiment. We made two incisions in the lower back of a 5-week-old male nude mouse, and implanted HA blocks. One was placed around the liver at the right side and another one was placed around the kidney at the left side. The organ fibrous capsule was not removed. At 6 weeks after implantation, mice were sacrificed under overanesthesia and HA blocks were retrieved and prepared for histological analysis. In the HE stain of HA blocks around liver, liver tissue is invaded into the HA pore areas. Hepatocyte proliferation in trabecular pattern was seen in contact with the surfaces of many HA pores. Within some pores, hepatic lobular pattern, Glisson sheath or central vein could be detected. In the HA around kidney, renal tissue was observed in many pores. The pore areas of HA were fullfilled with grumerulus and urinary tube tissues. In contact with the surfaces of some HA blocks, the tissue invasion of pancreas and spleen tissue were recognized. These results indicate that porous HA has a high affinity for the celiac organs, and has a stimulatory effect on celiac organ regeneration. Especially, concerning the regeneration of kidney, it has not been reported yet, so this report is very interesting. HA is also very useful as a scaffold of the organ regeneration.

Abstract: Dense and porous hydroxyapatite materials aimed at being used in controlled drug delivery, were characterised and studied in order to evaluate their ability to adsorb and release sodium ampicillin in a controlled manner, as a model for a drug delivery system, potentially applicable associated to surgery for the treatment of bone defects. These porous materials should also have adequate mechanical strength to withstand manipulation and sculpturing in surgery room. Adsorption and release profiles were obtained for a range of porous materials, leading to higher adsorption rates and more adequate release profiles than for dense materials.

Abstract: The adsorption behaviour of sodium ampicillin to dense and porous hydroxyapatite as been extensively studied through the obtention of an adsorption isotherm. This isotherm was produced at body temperature, and a wide range of antibiotic solutions was used. The adsorption behaviour was measured by UV spectroscopy. The shape of the isotherm for the two forms of the material, dense and porous, indicates that the adsorption behaviour of the antibiotic seems to be different; however, this is due to the adsorption taking place within the pores of the porous material, thus showing a larger amount of antibiotic adsorbed.