Fluorapatite/hydroxyapatite solid solution has better biological properties than other apatites, especially used as films or coatings. In this work, sol-gel preparation and in vitro behavior of fluorapatite/hydroxyapa...Fluorapatite/hydroxyapatite solid solution has better biological properties than other apatites, especially used as films or coatings. In this work, sol-gel preparation and in vitro behavior of fluorapatite/hydroxyapatite solid solution films on titanium alloy were investigated. Ca(NO3)2·4H2O and PO(OH)K(OEt)3-x. were selected as precursors, and hexafluorophosphoric acid (HPF6) was used as a fluorine containing reagent. The Ca and P precursors were mixed with HPF6 to keep the Ca/P molar ratio 1.67. The mixtures refluxed for 12 h were used as dipping sols for the preparation of the films. The phase of the films obtained at 600℃ was apatite. The F contents in the films increased with the concentrations of HPF6 in the dipping sols. The solid solution films were shown to have better stability than hydroxyapatite films, and a reasonably good bioactivity in the in vitro evaluation.展开更多
Hot pressing of hydroxyapatite(HA) Ti system material and the stability of HA component were investigated to supply the foundation of optimizing sintering procedure of HA Ti functionally graded material(FGM). The resu...Hot pressing of hydroxyapatite(HA) Ti system material and the stability of HA component were investigated to supply the foundation of optimizing sintering procedure of HA Ti functionally graded material(FGM). The results show that the HA powders used have excellent thermal stability and no decomposition is observed at 1 300 ℃. The existence of Ti can promote the dehydration and decomposition of HA. However, no new compounds form between HA and Ti. By selecting sintering parameters properly, ideal HA Ti material can be acquired. The relative densities of the mixtures of HA and Ti are always lower than those of pure HA or Ti, which may be caused by the decomposition of HA in the mixtures.展开更多
The composite films consisting of the titania gel impregnated with hydroxyapatite （HAP） submicron particles were prepared on commercial Ti6A14V plates processed by a sol-gel route. HAP powders were synthesized based...The composite films consisting of the titania gel impregnated with hydroxyapatite （HAP） submicron particles were prepared on commercial Ti6A14V plates processed by a sol-gel route. HAP powders were synthesized based on wet chemical precipitation method with Ca（NO3）2.4H2O and （NH4）2HPO4 as starting reagents. After being calcined at 900℃, HAP powders were ultrasonically scattered in ethanol to produce HAP sol. The titania sol was prepared using titanium （IV） isopropoxide {Ti[OCH（CH3）2]4} as precursor. Both the titania sol and the HAP/titania mixture were sequentially spin-coated on the substrates and calcined at various temperatures. The characteristics and mechanical adhesion of the composite films were investigated. The results show that the as-prepared films are dense, homogeneous, well-crystallized, and there is a good interfacial adhesion between the film and the substrate. The in vitro bioactivities of these films were discussed based on the analysis of the variations of Ca and P concentrations in the simulated body fluid and their surface morphologies against immersion time.展开更多
Calcium-based biocomposite materials have a pivotal role in the biomedical field with their diverse properties and applications in combating challenging medical problems. The study states the development and character...Calcium-based biocomposite materials have a pivotal role in the biomedical field with their diverse properties and applications in combating challenging medical problems. The study states the development and characterization of Calcium-based biocomposites: Hydroxyapatite (HAP), and PVA-Gelatin-HAP films. For the preparation of Calcium-based biocomposites, an unconventional source, the waste material calcite stone, was used as calcium raw material, and by the process of calcination, calcium oxide was synthesized. From calcium oxide, HAP was prepared by chemical precipitation method, which was later added in different proportions to PVA-Gelatin solution and finally dried to form biocomposite films. Then the different properties of PVA/Gelatin/HAP composite, for instance, chemical, mechanical, thermal, and swelling properties due to the incorporation of various proportions of HAP in PVA-Gelatin solution, were investigated. The characterization of the HAP was conducted by X-ray Diffraction Analysis, and the characterization of HAP-PVA-Gelatin composites was done by Fourier Transform Infrared Spectroscopy, Thermomechanical Analysis, Tensile test, Thermogravimetric Differential Thermal Analysis, and Swelling Test. The produced biocomposite films might have applications in orthopedic implants, drug delivery, bone tissue engineering, and wound healing.展开更多
Excellent firm bonding between the biomaterials and bone tissue (osseointegration and osteo-conductivity) has been desired for the stability in vivo of dental implants and artificial joints. Much has been learned abou...Excellent firm bonding between the biomaterials and bone tissue (osseointegration and osteo-conductivity) has been desired for the stability in vivo of dental implants and artificial joints. Much has been learned about this concept, which has led to significant improvements in the design and surface modification of implants in the field of implant dentistry, orthopedic surgery. We have already reported that low-intensity pulsed ultrasound (LIPUS) irradiation can accelerate the bone bonding ability of the bio-conductive materials such as bioactive titanium and hydroxyapatite implant. However, it is still unclear whether the LIPUS could have same effect to different types of the bioactive-materials. Therefore, in this study, the differences of bone-like hydroxyapatite formation on some kind of hydroxyapatite surface in simulated body fluid (SBF) under the LIPUS irradiation were investigated. Two kinds of hydroxyapatite samples immersed in SBF was exposed to ultrasound waves, the bone-like apatite on the surface was analyzed by Scanning electron microscopy and X-ray diffraction. As a result, the enhancement of hydroxyapatite formation on the surface by LIPUS was confirmed, the initial epitaxial nucleation and crystal growth of apatite depended on crystal structure of the surface of matrix materials.展开更多
Recently,magnesium and its alloys have attracted more and more attention as promising implant materials due to their excellent properties such as good biocompatibility,biodegradation,non-toxicity and comparable mechan...Recently,magnesium and its alloys have attracted more and more attention as promising implant materials due to their excellent properties such as good biocompatibility,biodegradation,non-toxicity and comparable mechanical properties with natural bone.They can be gradually degraded and absorbed so as to avoid the second surgery for implants removal after the tissues are healed completely.In addition,they are also able to prevent the stress shielding effect in human body environment because of the density,elastic modulus and yield strength of magnesium closer to the bone.Unfortunately,the high corrosion rate which causes early mechanical failure of the implants in physiological environment limits the widespread use of magnesium alloys for clinical application in biology.And the high corrosion process usually causes huge hydrogen evolution and alkalinization,resulting in problems against the implants as well as the surrounding tissues.In order to enhance the corrosion resistance of magnesium alloys,in this study,the ZEK100 magnesium alloy was pre-deformed with a highpressure torsion(HPT)process and then fabricated hydroxyapatite(HA)coatings with different contents of Mg(OH)2 nanopowder via hydrothermal method.The specimens were characterized by scanning electron microscope(SEM)and X-ray diffraction(XRD).At the same time,prior and after the HPT procedure,the metallography,microhardness and tensile tests of specimens were characterized.Meanwhile,the corrosion behavior of the specimens was evaluated by electrochemical impedance spectroscopy(EIS)and hydrogen evolution tests.And the interface bonding strength of the HA coating on the magnesium alloy substrate was evaluated by a tape adhesion test/scratch test.Results showed that HPT processing refined the grain size and introduced a great number of twins,resulting in the enhancement of microhardness and Young’s modulus of ZEK100 magnesium alloy,but hardness values at the edge were higher than those at the center due to the uneven shear strain.At the same conditions,the HA coating on HPT-ZEK was denser,thicker than that on ZEK sample and the crystal sizes of HA were smaller on HPT-ZEK.These were attributed to fine,uniform distributed secondary phases and lots of fine grains,twins,grain boundaries in HPT-ZEK substrates which can provide more nucleation sites for the HA crystal.In terms of the amount of Mg(OH)2 nanopowder,Mg(OH)2 nanopowder significantly influenced the microstructure and thickness of the HA coating.And at a 0.3 mg/mL content of Mg(OH)2 nanopowder,there was the densest,thickest HA coating on magnesium alloys,and the crystal size of HA was minimum.Specifically,the HA coating thickness on ZEK-03(0.3 mg/mL Mg(OH)2 nanopowder)was 1.8 times of that on ZEK-00(0 mg/mL Mg(OH)2 nanopowder),while the HA coating thickness on HPT-03 was 2.6 times of that on ZEK-00.And the adhesion strength of HA coating on HPT-03 substrate was better than that on ZEK-03.In addition,HPT technology and surface modification by HA coating simultaneously increased the corrosion resistance of ZEK100 magnesium alloy and the corrosion of HPT-ZEK samples occurred in a more uniform manner,while it was pitting on the surface of ZEK100 magnesium alloy.Therefore,there was the best corrosion resistance on HPT-03 sample,which could promote the application of magnesium alloys in biomedical fields.展开更多
The composite films constituted of hydroxyapatite (HAP) submicron particles embedded in the gel composed of the titania nanoparticles were prepared on commercial Ti6Al4V plates with titania buffer layer obtained by a ...The composite films constituted of hydroxyapatite (HAP) submicron particles embedded in the gel composed of the titania nanoparticles were prepared on commercial Ti6Al4V plates with titania buffer layer obtained by a spin-coating technique. The films were annealed in air at 450 ℃, 550 ℃ and 650 ℃, respectively. The phase formation, surface morphology, andinterfacial microstructure of the films were investigated by X-ray diffraction(XRD),Fourier transform infrared spectroscopy (FT-IR), field emission-scanning electron microscopy(FE-SEM) and energy dispersive X-ray (EDS) analysis. The results show that the as-prepared films are all well-crystallized, dense,homogeneous, and there was a close interfacial bond between the film and the substrate. The results of adhesion test indicate that there is a good bonding strength between the film and the substrate. The bone-like apatite formation on the surface of the films after immersion in acellular simulatedbody fluid(SBF) validated their bioactivities.展开更多
Sintering shrinkage, compressive strength, bending strength, chemical composition and their relationships with mi-crostructure of HA-Ti and HA-BG-Ti biomaterials were studied. The results show that sintering shrinkage...Sintering shrinkage, compressive strength, bending strength, chemical composition and their relationships with mi-crostructure of HA-Ti and HA-BG-Ti biomaterials were studied. The results show that sintering shrinkage curve of HA-BG-Ti composite changes just like S shape (23.1%-16.2%-21.8%-17.1%) with increase of Ti content, and sintering shrinkage of HA-BG-Ti composite is always higher than that of HA-Ti composite. The approach also indicates that compressive strength and bending strength of HA-BG-Ti composite are always higher than that of HA-Ti composite. Basically, with its compressive strength and bending strength equaling to 211.5 MPa and 132.1 MPa respectively, HA-10 vol. pct BG-60 vol. pct Ti composite can meet the mechanical properties requirements of the outer dense bulk. Furthermore, microstructure analysis shows that interfacial integration of HA-BG-Ti composite is better than that of HA-Ti composite. From X-ray diffraction (XRD) and SEM-EDAX analysis, brittle new phases including calcium titanate and calcium carbonate are detected in HA-Ti composite. New phases in HA-Ti composite and complex strong binding force accompanied by elemental diffusion of Si, Ti in HA-BG-Ti composite can explain theoretically the great difference of mechanical properties of HA-Ti and HA-BG-Ti composites.展开更多
Nano-hydroxyapatite/poly（e-caprolactone） （nHA/PCL） composite materials are among the best candidates for application in bone tissue engineering. As the main technique to fabricate porous scaffolds, electrospilming...Nano-hydroxyapatite/poly（e-caprolactone） （nHA/PCL） composite materials are among the best candidates for application in bone tissue engineering. As the main technique to fabricate porous scaffolds, electrospilming produce scaffolds with unsatisfactory mechanical strength and limited pore size for cdi infiltration. Micron-sized fiber assembly with higher mechanical strength is qualified to structure hybrid scaffolds. In this study, nHA/PCL monofilament fibers with different mass ratios were fabricated through melt-spinning. Transmission electron microscope （TEM） was used to observe the aggregation between nHA parfides. Other characterizations including scanning electron microscopy （SEM）, attenuated total reflection Fourier transform infrared spectroscopy （ATR.FTIR） and X-ray diffraction （XRD） were done to discuss the morphology, components and crystallization of the nHA/PCL composite fibers, respectively. The influence of nHA/PCL mass ratio on the tensile properties and water contact angle of composite fibers was also studied. The SEM images show the homogeneous dispersion of nano partides in the polymer matrix. Besides, nHA content increases the tensile strength, initial modulus and hydrophillcity of the composite fibers under the premise of spinnability. This kind of fibers is strong enough to fabricate fiber assembly which may have potential application in bone tissue engineering.展开更多
基金Zhejiang Provincial Natural Science Foundation of China(598061)the research fund of the Doctoral Program of Higher Education(98033536)China-Portugal Cooperation Project for supporting the work.
文摘Fluorapatite/hydroxyapatite solid solution has better biological properties than other apatites, especially used as films or coatings. In this work, sol-gel preparation and in vitro behavior of fluorapatite/hydroxyapatite solid solution films on titanium alloy were investigated. Ca(NO3)2·4H2O and PO(OH)K(OEt)3-x. were selected as precursors, and hexafluorophosphoric acid (HPF6) was used as a fluorine containing reagent. The Ca and P precursors were mixed with HPF6 to keep the Ca/P molar ratio 1.67. The mixtures refluxed for 12 h were used as dipping sols for the preparation of the films. The phase of the films obtained at 600℃ was apatite. The F contents in the films increased with the concentrations of HPF6 in the dipping sols. The solid solution films were shown to have better stability than hydroxyapatite films, and a reasonably good bioactivity in the in vitro evaluation.
文摘Hot pressing of hydroxyapatite(HA) Ti system material and the stability of HA component were investigated to supply the foundation of optimizing sintering procedure of HA Ti functionally graded material(FGM). The results show that the HA powders used have excellent thermal stability and no decomposition is observed at 1 300 ℃. The existence of Ti can promote the dehydration and decomposition of HA. However, no new compounds form between HA and Ti. By selecting sintering parameters properly, ideal HA Ti material can be acquired. The relative densities of the mixtures of HA and Ti are always lower than those of pure HA or Ti, which may be caused by the decomposition of HA in the mixtures.
基金This work was financially supported by the National Natural Science Foundation of China (No.50235020).
文摘The composite films consisting of the titania gel impregnated with hydroxyapatite （HAP） submicron particles were prepared on commercial Ti6A14V plates processed by a sol-gel route. HAP powders were synthesized based on wet chemical precipitation method with Ca（NO3）2.4H2O and （NH4）2HPO4 as starting reagents. After being calcined at 900℃, HAP powders were ultrasonically scattered in ethanol to produce HAP sol. The titania sol was prepared using titanium （IV） isopropoxide {Ti[OCH（CH3）2]4} as precursor. Both the titania sol and the HAP/titania mixture were sequentially spin-coated on the substrates and calcined at various temperatures. The characteristics and mechanical adhesion of the composite films were investigated. The results show that the as-prepared films are dense, homogeneous, well-crystallized, and there is a good interfacial adhesion between the film and the substrate. The in vitro bioactivities of these films were discussed based on the analysis of the variations of Ca and P concentrations in the simulated body fluid and their surface morphologies against immersion time.
文摘Calcium-based biocomposite materials have a pivotal role in the biomedical field with their diverse properties and applications in combating challenging medical problems. The study states the development and characterization of Calcium-based biocomposites: Hydroxyapatite (HAP), and PVA-Gelatin-HAP films. For the preparation of Calcium-based biocomposites, an unconventional source, the waste material calcite stone, was used as calcium raw material, and by the process of calcination, calcium oxide was synthesized. From calcium oxide, HAP was prepared by chemical precipitation method, which was later added in different proportions to PVA-Gelatin solution and finally dried to form biocomposite films. Then the different properties of PVA/Gelatin/HAP composite, for instance, chemical, mechanical, thermal, and swelling properties due to the incorporation of various proportions of HAP in PVA-Gelatin solution, were investigated. The characterization of the HAP was conducted by X-ray Diffraction Analysis, and the characterization of HAP-PVA-Gelatin composites was done by Fourier Transform Infrared Spectroscopy, Thermomechanical Analysis, Tensile test, Thermogravimetric Differential Thermal Analysis, and Swelling Test. The produced biocomposite films might have applications in orthopedic implants, drug delivery, bone tissue engineering, and wound healing.
文摘Excellent firm bonding between the biomaterials and bone tissue (osseointegration and osteo-conductivity) has been desired for the stability in vivo of dental implants and artificial joints. Much has been learned about this concept, which has led to significant improvements in the design and surface modification of implants in the field of implant dentistry, orthopedic surgery. We have already reported that low-intensity pulsed ultrasound (LIPUS) irradiation can accelerate the bone bonding ability of the bio-conductive materials such as bioactive titanium and hydroxyapatite implant. However, it is still unclear whether the LIPUS could have same effect to different types of the bioactive-materials. Therefore, in this study, the differences of bone-like hydroxyapatite formation on some kind of hydroxyapatite surface in simulated body fluid (SBF) under the LIPUS irradiation were investigated. Two kinds of hydroxyapatite samples immersed in SBF was exposed to ultrasound waves, the bone-like apatite on the surface was analyzed by Scanning electron microscopy and X-ray diffraction. As a result, the enhancement of hydroxyapatite formation on the surface by LIPUS was confirmed, the initial epitaxial nucleation and crystal growth of apatite depended on crystal structure of the surface of matrix materials.
基金sponsored by the National Natural Science Foundation of China ( 51571150,11572222)Tianjin Natural Science Foundation ( 14JCYBJC16900)
文摘Recently,magnesium and its alloys have attracted more and more attention as promising implant materials due to their excellent properties such as good biocompatibility,biodegradation,non-toxicity and comparable mechanical properties with natural bone.They can be gradually degraded and absorbed so as to avoid the second surgery for implants removal after the tissues are healed completely.In addition,they are also able to prevent the stress shielding effect in human body environment because of the density,elastic modulus and yield strength of magnesium closer to the bone.Unfortunately,the high corrosion rate which causes early mechanical failure of the implants in physiological environment limits the widespread use of magnesium alloys for clinical application in biology.And the high corrosion process usually causes huge hydrogen evolution and alkalinization,resulting in problems against the implants as well as the surrounding tissues.In order to enhance the corrosion resistance of magnesium alloys,in this study,the ZEK100 magnesium alloy was pre-deformed with a highpressure torsion(HPT)process and then fabricated hydroxyapatite(HA)coatings with different contents of Mg(OH)2 nanopowder via hydrothermal method.The specimens were characterized by scanning electron microscope(SEM)and X-ray diffraction(XRD).At the same time,prior and after the HPT procedure,the metallography,microhardness and tensile tests of specimens were characterized.Meanwhile,the corrosion behavior of the specimens was evaluated by electrochemical impedance spectroscopy(EIS)and hydrogen evolution tests.And the interface bonding strength of the HA coating on the magnesium alloy substrate was evaluated by a tape adhesion test/scratch test.Results showed that HPT processing refined the grain size and introduced a great number of twins,resulting in the enhancement of microhardness and Young’s modulus of ZEK100 magnesium alloy,but hardness values at the edge were higher than those at the center due to the uneven shear strain.At the same conditions,the HA coating on HPT-ZEK was denser,thicker than that on ZEK sample and the crystal sizes of HA were smaller on HPT-ZEK.These were attributed to fine,uniform distributed secondary phases and lots of fine grains,twins,grain boundaries in HPT-ZEK substrates which can provide more nucleation sites for the HA crystal.In terms of the amount of Mg(OH)2 nanopowder,Mg(OH)2 nanopowder significantly influenced the microstructure and thickness of the HA coating.And at a 0.3 mg/mL content of Mg(OH)2 nanopowder,there was the densest,thickest HA coating on magnesium alloys,and the crystal size of HA was minimum.Specifically,the HA coating thickness on ZEK-03(0.3 mg/mL Mg(OH)2 nanopowder)was 1.8 times of that on ZEK-00(0 mg/mL Mg(OH)2 nanopowder),while the HA coating thickness on HPT-03 was 2.6 times of that on ZEK-00.And the adhesion strength of HA coating on HPT-03 substrate was better than that on ZEK-03.In addition,HPT technology and surface modification by HA coating simultaneously increased the corrosion resistance of ZEK100 magnesium alloy and the corrosion of HPT-ZEK samples occurred in a more uniform manner,while it was pitting on the surface of ZEK100 magnesium alloy.Therefore,there was the best corrosion resistance on HPT-03 sample,which could promote the application of magnesium alloys in biomedical fields.
基金Projects(50235020 30300078)supported by the National Natural Science Foundation of China
文摘The composite films constituted of hydroxyapatite (HAP) submicron particles embedded in the gel composed of the titania nanoparticles were prepared on commercial Ti6Al4V plates with titania buffer layer obtained by a spin-coating technique. The films were annealed in air at 450 ℃, 550 ℃ and 650 ℃, respectively. The phase formation, surface morphology, andinterfacial microstructure of the films were investigated by X-ray diffraction(XRD),Fourier transform infrared spectroscopy (FT-IR), field emission-scanning electron microscopy(FE-SEM) and energy dispersive X-ray (EDS) analysis. The results show that the as-prepared films are all well-crystallized, dense,homogeneous, and there was a close interfacial bond between the film and the substrate. The results of adhesion test indicate that there is a good bonding strength between the film and the substrate. The bone-like apatite formation on the surface of the films after immersion in acellular simulatedbody fluid(SBF) validated their bioactivities.
基金The authors are grateful for the financial support from the National Natural Science Foundation of China(No.50174059).
文摘Sintering shrinkage, compressive strength, bending strength, chemical composition and their relationships with mi-crostructure of HA-Ti and HA-BG-Ti biomaterials were studied. The results show that sintering shrinkage curve of HA-BG-Ti composite changes just like S shape (23.1%-16.2%-21.8%-17.1%) with increase of Ti content, and sintering shrinkage of HA-BG-Ti composite is always higher than that of HA-Ti composite. The approach also indicates that compressive strength and bending strength of HA-BG-Ti composite are always higher than that of HA-Ti composite. Basically, with its compressive strength and bending strength equaling to 211.5 MPa and 132.1 MPa respectively, HA-10 vol. pct BG-60 vol. pct Ti composite can meet the mechanical properties requirements of the outer dense bulk. Furthermore, microstructure analysis shows that interfacial integration of HA-BG-Ti composite is better than that of HA-Ti composite. From X-ray diffraction (XRD) and SEM-EDAX analysis, brittle new phases including calcium titanate and calcium carbonate are detected in HA-Ti composite. New phases in HA-Ti composite and complex strong binding force accompanied by elemental diffusion of Si, Ti in HA-BG-Ti composite can explain theoretically the great difference of mechanical properties of HA-Ti and HA-BG-Ti composites.
基金Science and Technology Support Program of Shanghai,China(No.16441903803)National Postdoctoral Foundation,China(No.2016M590299)
文摘Nano-hydroxyapatite/poly（e-caprolactone） （nHA/PCL） composite materials are among the best candidates for application in bone tissue engineering. As the main technique to fabricate porous scaffolds, electrospilming produce scaffolds with unsatisfactory mechanical strength and limited pore size for cdi infiltration. Micron-sized fiber assembly with higher mechanical strength is qualified to structure hybrid scaffolds. In this study, nHA/PCL monofilament fibers with different mass ratios were fabricated through melt-spinning. Transmission electron microscope （TEM） was used to observe the aggregation between nHA parfides. Other characterizations including scanning electron microscopy （SEM）, attenuated total reflection Fourier transform infrared spectroscopy （ATR.FTIR） and X-ray diffraction （XRD） were done to discuss the morphology, components and crystallization of the nHA/PCL composite fibers, respectively. The influence of nHA/PCL mass ratio on the tensile properties and water contact angle of composite fibers was also studied. The SEM images show the homogeneous dispersion of nano partides in the polymer matrix. Besides, nHA content increases the tensile strength, initial modulus and hydrophillcity of the composite fibers under the premise of spinnability. This kind of fibers is strong enough to fabricate fiber assembly which may have potential application in bone tissue engineering.
