Bone-like hydroxyapatite （ HAp ） powders were synthesized using a reverse microemulsion method without further calcine processing. Synthesis conditions had significant effects on the formation of HAp. According to t...Bone-like hydroxyapatite （ HAp ） powders were synthesized using a reverse microemulsion method without further calcine processing. Synthesis conditions had significant effects on the formation of HAp. According to the results of XRD patterns and FFIR spectra, the obtained needle shape HAp powder with poorly crystallized and carbonate substitution was chemically and structurally similar to the human bone powders. The alkaline of emulsion was responsible for the obtained HAp without calcine route, and carbonate came from CO2 in air during preparation. By ultrasonic treatment, the morphology of HAp particles changed from spherical to needle shape for the reverse micelles broke up due to the high energy of ultrasonic.展开更多
HA/316L stainless steel(316L SS) biocomposites were prepared by hot-pressing technique. The formation of bone-like apatite on the biocomposite surfaces in simulated body fluid(SBF) was analyzed by digital pH meter,pla...HA/316L stainless steel(316L SS) biocomposites were prepared by hot-pressing technique. The formation of bone-like apatite on the biocomposite surfaces in simulated body fluid(SBF) was analyzed by digital pH meter,plasma emission spectrometer,scanning electron microscope(SEM) and energy dispersive X-ray energy spectrometer(EDX). The results indicate that the pH value in SBF varies slightly during the immersion. It is a dynamic process of dissolution-precipitation for the formation of apatite on the surface. With prolonging immersion time,Ca and P ion concentrations increase gradually,and then approach equilibrium. The bone-like apatite layer forms on the composites surface,which possesses benign bioactivity and favorable biocompatibility and achieves osseointegration,and can provide firm fixation between HA60/316L SS composite implants and human body bone.展开更多
The objective of this work was to fabricate a rigid,resorbable and osteoconductive scaffold by mimicking the hierarchical structure of the cortical bone.Aligned peptide-functionalize nanofiber microsheets were generat...The objective of this work was to fabricate a rigid,resorbable and osteoconductive scaffold by mimicking the hierarchical structure of the cortical bone.Aligned peptide-functionalize nanofiber microsheets were generated with calcium phosphate(CaP)content similar to that of the natural cortical bone.Next,the CaP-rich fibrous microsheets were wrapped around a microneedle to form a laminated microtube mimicking the structure of an osteon.Then,a set of the osteon-mimetic microtubes were assembled around a solid rod and the assembly was annealed to fuse the microtubes and form a shell.Next,an array of circular microholes were drilled on the outer surface of the shell to generate a cortical bone-like scaffold with an interconnected network of Haversian-and Volkmann-like microcanals.The CaP content,porosity and density of the bone-mimetic microsheets were 240 wt%,8%and 1.9 g/ml,respectively,which were close to that of natural cortical bone.The interconnected network of microcanals in the fused microtubes increased permeability of a model protein in the scaffold.The cortical scaffold induced osteogenesis and vasculogenesis in the absence of bone morphogenetic proteins upon seeding with human mesenchymal stem cells and endothelial colony-forming cells.The localized and timed-release of morphogenetic factors significantly increased the extent of osteogenic and vasculogenic differentiation of human mesenchymal stem cells and endothelial colony-forming cells in the cortical scaffold.The cortical bonemimetic nature of the cellular construct provided balanced rigidity,resorption rate,osteoconductivity and nutrient diffusivity to support vascularization and osteogenesis.展开更多
Background： Recently, local sustained-release antibiotics systems have been developed because they can increase local loci of concentrated antibiotics without increasing the plasma concentration, and thereby effectiv...Background： Recently, local sustained-release antibiotics systems have been developed because they can increase local loci of concentrated antibiotics without increasing the plasma concentration, and thereby effectively decrease any systemic toxicity and side effects. A vancomycin-loaded bone-like hydroxyapatite/poly-amino acid （V-BHA/PAA） bony scaffold was successfully fabricated with vancomycin-loaded poly lactic-co-glycolic acid microspheres and BHA/PAA, which was demonstrated to exhibit both porosity and perfect biodegradability. The aim of this study was to systematically evaluate the biosafety of this novel scaffold by conducting toxicity tests in vitro and in vivo. Methods： According to the ISO rules for medical implant biosafety, for in vitro tests, the scaffold was incubated with L929 fibroblasts or rabbit noncoagulant blood, with simultaneous creation of positive control and negative control groups. The growth condition ofL929 cells and hemolytic ratio were respectively evaluated after various incubation periods. For in vivo tests, a chronic osteomyelitis model involving the right proximal tibia of New Zealand white rabbits was established. After bacterial identification, the drug-loaded scaffold, drug-unloaded BHA/PAA, and poly （methyl methacrylate） were implanted, and a blank control group was also set up. Subsequently, the in vivo blood drug concentrations were measured, and the kidney and liver functions were evaluated. Results： In the in vitro tests, the cytotoxicity grades of V-BHA/PAA and BHA/PAA-based on the relative growth rate were all below 1. The hemolysis ratios of V-BHA/PAA and BHA/PAA were 2.27% and 1.42%, respectively, both below 5%. In the in vivo tests, the blood concentration of vancomycin after implantation of V-BHA/PAA was measured at far below its toxic concentration （60 mg/L）, and the function and histomorphology of the liver and kidney were all normal. Conclusion： According to ISO standards, the V-BHA/PAA scaffold is considered to have sufficient safety for clinical utilization.展开更多
A novel method has been developed to rapidly deposit bone-like apatite with the assistance of ultraviolet （UV） light irradiation on the nanostructured titania in the simulated body fluid （SBF）. The process has thr...A novel method has been developed to rapidly deposit bone-like apatite with the assistance of ultraviolet （UV） light irradiation on the nanostructured titania in the simulated body fluid （SBF）. The process has three main steps： Ti-24Nb-4Zr-7.9Sn alloy was heated at 650℃ for 3 h, UV-light illumination in air for 4 h and soaking in the SBF for 3 d. A titania coating consisted of main rutile formed on the thermal oxidized Ti-24Nb-4Zr- 7.9Sn alloy. The UV not only converted the futile surface from hydrophilic to hydrophobic but also stimulated high surface activity. After 4 h UV illumination, the contents of Ti3＋ and hydroxyl groups on the oxidized sample were increased, while that of lattice O decreased. After 3 d of soaking in the SBF, a compact and uniform layer of carbonated hydroxyapatite （CHA） particles was formed on the UV-illuminated rutile surface whereas there was a few of HA to be viewed on the surface of as-oxidized Ti-24Nb-4Zr-7.9Sn alloy. Our study demonstrates a simple, fast and cost-effective technique for growing bone-like apatite on titanium alloys.展开更多
文摘Bone-like hydroxyapatite （ HAp ） powders were synthesized using a reverse microemulsion method without further calcine processing. Synthesis conditions had significant effects on the formation of HAp. According to the results of XRD patterns and FFIR spectra, the obtained needle shape HAp powder with poorly crystallized and carbonate substitution was chemically and structurally similar to the human bone powders. The alkaline of emulsion was responsible for the obtained HAp without calcine route, and carbonate came from CO2 in air during preparation. By ultrasonic treatment, the morphology of HAp particles changed from spherical to needle shape for the reverse micelles broke up due to the high energy of ultrasonic.
基金Project(50774096) and project (50604017) supported by the National Natural Science Foundation of ChinaProject(1343-74334000011) supported by the Postgraduate Education and Innovation Project from Central South University, China
文摘HA/316L stainless steel(316L SS) biocomposites were prepared by hot-pressing technique. The formation of bone-like apatite on the biocomposite surfaces in simulated body fluid(SBF) was analyzed by digital pH meter,plasma emission spectrometer,scanning electron microscope(SEM) and energy dispersive X-ray energy spectrometer(EDX). The results indicate that the pH value in SBF varies slightly during the immersion. It is a dynamic process of dissolution-precipitation for the formation of apatite on the surface. With prolonging immersion time,Ca and P ion concentrations increase gradually,and then approach equilibrium. The bone-like apatite layer forms on the composites surface,which possesses benign bioactivity and favorable biocompatibility and achieves osseointegration,and can provide firm fixation between HA60/316L SS composite implants and human body bone.
基金supported by research grants to E.Jabbari from the National Science Foundation under Award Numbers CBET1403545 and IIP150024 and the National Institute of Arthritis and Musculoskeletal and Skin Diseases of the National Institutes of Health under Award Number AR063745.
文摘The objective of this work was to fabricate a rigid,resorbable and osteoconductive scaffold by mimicking the hierarchical structure of the cortical bone.Aligned peptide-functionalize nanofiber microsheets were generated with calcium phosphate(CaP)content similar to that of the natural cortical bone.Next,the CaP-rich fibrous microsheets were wrapped around a microneedle to form a laminated microtube mimicking the structure of an osteon.Then,a set of the osteon-mimetic microtubes were assembled around a solid rod and the assembly was annealed to fuse the microtubes and form a shell.Next,an array of circular microholes were drilled on the outer surface of the shell to generate a cortical bone-like scaffold with an interconnected network of Haversian-and Volkmann-like microcanals.The CaP content,porosity and density of the bone-mimetic microsheets were 240 wt%,8%and 1.9 g/ml,respectively,which were close to that of natural cortical bone.The interconnected network of microcanals in the fused microtubes increased permeability of a model protein in the scaffold.The cortical scaffold induced osteogenesis and vasculogenesis in the absence of bone morphogenetic proteins upon seeding with human mesenchymal stem cells and endothelial colony-forming cells.The localized and timed-release of morphogenetic factors significantly increased the extent of osteogenic and vasculogenic differentiation of human mesenchymal stem cells and endothelial colony-forming cells in the cortical scaffold.The cortical bonemimetic nature of the cellular construct provided balanced rigidity,resorption rate,osteoconductivity and nutrient diffusivity to support vascularization and osteogenesis.
基金This study was supported by a grant from the National Natural Science Foundation of China
文摘Background： Recently, local sustained-release antibiotics systems have been developed because they can increase local loci of concentrated antibiotics without increasing the plasma concentration, and thereby effectively decrease any systemic toxicity and side effects. A vancomycin-loaded bone-like hydroxyapatite/poly-amino acid （V-BHA/PAA） bony scaffold was successfully fabricated with vancomycin-loaded poly lactic-co-glycolic acid microspheres and BHA/PAA, which was demonstrated to exhibit both porosity and perfect biodegradability. The aim of this study was to systematically evaluate the biosafety of this novel scaffold by conducting toxicity tests in vitro and in vivo. Methods： According to the ISO rules for medical implant biosafety, for in vitro tests, the scaffold was incubated with L929 fibroblasts or rabbit noncoagulant blood, with simultaneous creation of positive control and negative control groups. The growth condition ofL929 cells and hemolytic ratio were respectively evaluated after various incubation periods. For in vivo tests, a chronic osteomyelitis model involving the right proximal tibia of New Zealand white rabbits was established. After bacterial identification, the drug-loaded scaffold, drug-unloaded BHA/PAA, and poly （methyl methacrylate） were implanted, and a blank control group was also set up. Subsequently, the in vivo blood drug concentrations were measured, and the kidney and liver functions were evaluated. Results： In the in vitro tests, the cytotoxicity grades of V-BHA/PAA and BHA/PAA-based on the relative growth rate were all below 1. The hemolysis ratios of V-BHA/PAA and BHA/PAA were 2.27% and 1.42%, respectively, both below 5%. In the in vivo tests, the blood concentration of vancomycin after implantation of V-BHA/PAA was measured at far below its toxic concentration （60 mg/L）, and the function and histomorphology of the liver and kidney were all normal. Conclusion： According to ISO standards, the V-BHA/PAA scaffold is considered to have sufficient safety for clinical utilization.
基金The authors acknowledge the financial support for this work from the National Natural Science Foundation of China （Grant No. 51371126） and the Science and Technology Plan Project of Binhai new area of Tianjin （2012-BK120024）.
文摘A novel method has been developed to rapidly deposit bone-like apatite with the assistance of ultraviolet （UV） light irradiation on the nanostructured titania in the simulated body fluid （SBF）. The process has three main steps： Ti-24Nb-4Zr-7.9Sn alloy was heated at 650℃ for 3 h, UV-light illumination in air for 4 h and soaking in the SBF for 3 d. A titania coating consisted of main rutile formed on the thermal oxidized Ti-24Nb-4Zr- 7.9Sn alloy. The UV not only converted the futile surface from hydrophilic to hydrophobic but also stimulated high surface activity. After 4 h UV illumination, the contents of Ti3＋ and hydroxyl groups on the oxidized sample were increased, while that of lattice O decreased. After 3 d of soaking in the SBF, a compact and uniform layer of carbonated hydroxyapatite （CHA） particles was formed on the UV-illuminated rutile surface whereas there was a few of HA to be viewed on the surface of as-oxidized Ti-24Nb-4Zr-7.9Sn alloy. Our study demonstrates a simple, fast and cost-effective technique for growing bone-like apatite on titanium alloys.
