A systematic research was performed about diffusion kinetics of adsorbing F^- dissolved in water for carbonate hydroxyapatite （CHAP） from the natural hydroxyapatite which was modified by adulterating with CO3^2-. Th...A systematic research was performed about diffusion kinetics of adsorbing F^- dissolved in water for carbonate hydroxyapatite （CHAP） from the natural hydroxyapatite which was modified by adulterating with CO3^2-. The result shows that the speed of F^- adsorption is controlled by membrane diffusion when F^- concentration is relatively low, which is expressed by the kinetic equation of diffusion Q=0.0005（Ci-C）（t-ti）＋0.3967, or by vacancy diffusion when F^- concentration is relatively high, which is expressed by the kinetic equation of diffusion In[C（o, t）]=8.4718-0.5048Int. Based on the feature of CHAP for adsorbing F^- dissolved in water and its special channel of the structure of CO3^3- modified hydroxyapatite, models of vacancy diffusion and membrane diffusion were established.展开更多
The objective of this study is to present a simple method of statistical calculation that allowed us to determine the relationship between the different data obtained from the characterization of the synthetic carbona...The objective of this study is to present a simple method of statistical calculation that allowed us to determine the relationship between the different data obtained from the characterization of the synthetic carbonated apatites containing sodium, in order to find the fundamental substitution mechanism(s) for incorporation of Na+ and?CO32- and to establish the general formula. For that, a series of hydroxyapatites containing carbonate and sodium (Na-CO3HAps) has been obtained by the precipitation method. All the compounds were characterized by infrared spectra (IR), powder X-ray diffraction (PXRD) and elemental analysis. The statistical treatment of the experiment result allows us to determine the relationship between one variable and the change in the other and to found the fundamental substitution mechanism(s) for incorporation of Na+ and?CO32- . Analysis of variance (ANOVA) allows us to test the models proposed.展开更多
Kinetics and mechanisms on the removal of aqueous lead ion by carbonate hydroxyapatite （CHap） are investigated in the present work. Experimental results show that, in the whole pH range, the lead removal percentage ...Kinetics and mechanisms on the removal of aqueous lead ion by carbonate hydroxyapatite （CHap） are investigated in the present work. Experimental results show that, in the whole pH range, the lead removal percentage increases with decreasing pH values and reaches a maximum at pH=2-3. Under some conditions, the lead residual concentration is below national integrated wastewater discharge standard, even drinking water standard. The removal behavior is a complicated non-homogeneous solid/liquid reaction, which can be described by two stages from kinetic point of view. At the earlier stage, reaction rate is so fast that its kinetic course is intricate, which requires further study. At the latter stage, the rate of reaction becomes slow and the process of reaction accords with one order reaction kinetic equation. Experimental results show that the relationship between reaction rate constant k1 and temperature T accords to Arrhenius Equation, and the activation energy of sorption （Ea） is 11.93 kJ/mol and frequency factor （A） is 2.51 s^-1. X-ray diffraction （XRD）, scanning electron microscopy with an energy dispersive X-ray fluoresence spectrometer （SEM-EDS） and toxicity characteristic leaching procedure （TCLP） test were conducted in this work. It is indicated that the main mechanism is dissolution-precipitation, accompanying with superficial sorption.展开更多
Nanocrystal carbonated hydroxyapatite was prepared by lecithin-controlled chemical precipitation in synthetic body fluid （SBF）. The reactant was aged and heated at 850℃ for crystallization. The morphology and mic...Nanocrystal carbonated hydroxyapatite was prepared by lecithin-controlled chemical precipitation in synthetic body fluid （SBF）. The reactant was aged and heated at 850℃ for crystallization. The morphology and microstructure of the carbonated hydroxyapatite were investigated using transmission electron microscope （TEM）, X-ray diffraction （ XRD ） and FTIR. The experimental results demonstrate that the shapes of carbonated hydroxyapdtite particles display spheres with the average size of 20- 28 nm, and carbonated hydroxyapatite contained carbonate ions, similar to mineral of bone tissues.展开更多
The mixture of CaHPO 4·2H 2O and CaCO 3 was ground in an aqueous system under appropriate conditions to investigate the mechanochemical reaction for the synthesis of crystalline hydroxyapatite (HA) powder. Hyd...The mixture of CaHPO 4·2H 2O and CaCO 3 was ground in an aqueous system under appropriate conditions to investigate the mechanochemical reaction for the synthesis of crystalline hydroxyapatite (HA) powder. Hydroxyapatite of high crystallinity powder including trace Ca 10 (PO 4) 6CO 3(OH) and Ca 9HPO 4(PO 4) 6OH can be synthesized by mechanical activation without further thermal treatment at a high temperature. The synthesis reaction during the grinding process was almost completed within 1h. The as-ground powder exhibits a particle distribution of 20-100nm in size with a spherical or rodlike morphology. The composition and degree of crystallinity of the mechanochemical synthesized hydroxyapatite powders were coincident with the cement-type hydroxyapatite.展开更多
Bacterial infection is a major problem following bone implant surgery.Moreover,poly-l-lactic acid/carbon nanotube/hydroxyapatite(PLLA/CNT/HAP)bone scaffolds possess enhanced mechanical properties and show good bioacti...Bacterial infection is a major problem following bone implant surgery.Moreover,poly-l-lactic acid/carbon nanotube/hydroxyapatite(PLLA/CNT/HAP)bone scaffolds possess enhanced mechanical properties and show good bioactiv-ityregardingbonedefectregeneration.Inthisstudy,wesynthesizedsilver(Ag)-dopedCNT/HAP(CNT/Ag-HAP)nanohybrids via the partial replacing of calcium ions(Ca2+)in the HAP lattice with silver ions(Ag+)using an ion doping technique under hydrothermal conditions.Specifically,the doping process was induced using the special lattice structure of HAP and the abundant surface oxygenic functional groups of CNT,and involved the partial replacement of Ca2+in the HAP lattice by doped Ag+as well as the in situ synthesis of Ag-HAP nanoparticles on CNT in a hydrothermal environment.The result-ing CNT/Ag-HAP nanohybrids were then introduced into a PLLA matrix via laser-based powder bed fusion(PBF-LB)to fabricate PLLA/CNT/Ag-HAP scaffolds that showed sustained antibacterial activity.We then found that Ag+,which pos-sesses broad-spectrum antibacterial activity,endowed PLLA/CNT/Ag-HAP scaffolds with this activity,with an antibacterial effectiveness of 92.65%.This antibacterial effect is due to the powerful effect of Ag+against bacterial structure and genetic material,as well as the physical destruction of bacterial structures due to the sharp edge structure of CNT.In addition,the scaffold possessed enhanced mechanical properties,showing tensile and compressive strengths of 8.49 MPa and 19.72 MPa,respectively.Finally,the scaffold also exhibited good bioactivity and cytocompatibility,including the ability to form apatite layers and to promote the adhesion and proliferation of human osteoblast-like cells(MG63 cells).展开更多
Scaffolds with multimodal pore structure are essential to cells differentiation and proliferation in bone tissue engineering. Bi-/multi-modal porous PLGA/hydroxyapatite composite scaffolds were prepared by supercritic...Scaffolds with multimodal pore structure are essential to cells differentiation and proliferation in bone tissue engineering. Bi-/multi-modal porous PLGA/hydroxyapatite composite scaffolds were prepared by supercritical C02 foaming in which hydroxyapatite acted as heterogeneous nucleation agent. Bimodal porous scaffolds were prepared under certain conditions, i.e. hydroxyapatite addition of 5%, depressurization rate of 0.3 MPa. min-1, soaking temperature of 55 ℃, and pressure of 9 MPa. And scaffolds presented specific structure of small pores （122 μM ± 66 μm） in the cellular walls of large pores （552 μm ±127 μm）. Furthermore, multimodal porous PLGA scaffolds with micro-pores （37 μM ± 11μM） were obtained at low soaking pressure of 7.5 MPa. The interconnected porosity of scaffolds ranged from （52.53 ± 2.69）% to （83.08±2.42）% by adjusting depressurization rate, while compression modulus satisfied the requirement of bone tissue engineering. Solvent-free CO2 foaming method is promising to fabricate bi-/multi-modal porous scaffolds in one step, and bioactive particles for osteogenesis could serve as nucleation agents.展开更多
Hydroxyapatite(HA)and its composites with inorganic additives,dopants,and polymers is a rapidly developing branch in the materials chemistry.In particular,carbon allotropes are widely used in these composites being wi...Hydroxyapatite(HA)and its composites with inorganic additives,dopants,and polymers is a rapidly developing branch in the materials chemistry.In particular,carbon allotropes are widely used in these composites being widely applied for medical purposes.Observing a gap of insufficient generalization of recent achievements in the field of the HA/Carbon composites,in this review we present the state of the art of the field of HA composites and hybrids with classic carbon allotropes and nanocarbons.These composites are known for carbon nanotubes,nanofibers,graphene and its oxidized forms,as well as,in a lesser grade,for graphite,fullerenes,nanodiamonds,carbon nanofoams,etc.These composites can be fabricated by a variety of classic and less-common methods,such as co-precipitation(with or without ultrasonic treatment),CVD,hot isostatic pressing,hydrothermal,spark plasma sintering,biomimetic mineralization,thermal and plasma spray,electrochemical and electrophoretic deposition,self-assembling,3D printing,electrospinning,and lyophilisation,among others.Combination of various synthesis techniques can be also carried out for composite preparation.Natural or synthetic HA can be used as it is for further interaction with carbon allotropes or it can be first prepared and then reacted with carbon counterpart;similarly,carbon allotropes can be introduced into the interaction with HA directly or they can be first synthesized,in particular from biomass.Resulting biocompatible composites can be produced in the form of coatings,powders,and scaffolds and can additionally contain quantitative amounts of third phases,frequently natural or synthetic polymers.In these composites,especially with O-containing functionalizing groups,HA disadvantages could be considerably decreased with simultaneous enhancement of mechanical properties,becoming similar to human bone,chemical stability and biocompatibility,as well as possessing antibacterial effect.GO→G reduction and higher HA decoration were observed in several experiments.The morphology of polymer-containing HA/GO composites can be tuned by variations of GO:polymer ratios.Predominant number of resulting applications of formed HA composites corresponds to the biomedical area,mainly for orthopedic applications/implants,osteoporosis treatment,myocardial,skin and dental regeneration,etc.Other important uses include applications as adsorbents for the elimination of impurities from wastewaters and/or removal/uptake of heavy metal cations,loading several medicines,and energy storage materials.Biocompatibility and hemocompatibility aspects of HA/Carbon composites are also discussed and future developments are proposed.展开更多
基金the key scientific foundation(No.2001Z20004)the Hubei Provincial Department of Education and the natural science foundation(2005ABA024)
文摘A systematic research was performed about diffusion kinetics of adsorbing F^- dissolved in water for carbonate hydroxyapatite （CHAP） from the natural hydroxyapatite which was modified by adulterating with CO3^2-. The result shows that the speed of F^- adsorption is controlled by membrane diffusion when F^- concentration is relatively low, which is expressed by the kinetic equation of diffusion Q=0.0005（Ci-C）（t-ti）＋0.3967, or by vacancy diffusion when F^- concentration is relatively high, which is expressed by the kinetic equation of diffusion In[C（o, t）]=8.4718-0.5048Int. Based on the feature of CHAP for adsorbing F^- dissolved in water and its special channel of the structure of CO3^3- modified hydroxyapatite, models of vacancy diffusion and membrane diffusion were established.
文摘The objective of this study is to present a simple method of statistical calculation that allowed us to determine the relationship between the different data obtained from the characterization of the synthetic carbonated apatites containing sodium, in order to find the fundamental substitution mechanism(s) for incorporation of Na+ and?CO32- and to establish the general formula. For that, a series of hydroxyapatites containing carbonate and sodium (Na-CO3HAps) has been obtained by the precipitation method. All the compounds were characterized by infrared spectra (IR), powder X-ray diffraction (PXRD) and elemental analysis. The statistical treatment of the experiment result allows us to determine the relationship between one variable and the change in the other and to found the fundamental substitution mechanism(s) for incorporation of Na+ and?CO32- . Analysis of variance (ANOVA) allows us to test the models proposed.
文摘Kinetics and mechanisms on the removal of aqueous lead ion by carbonate hydroxyapatite （CHap） are investigated in the present work. Experimental results show that, in the whole pH range, the lead removal percentage increases with decreasing pH values and reaches a maximum at pH=2-3. Under some conditions, the lead residual concentration is below national integrated wastewater discharge standard, even drinking water standard. The removal behavior is a complicated non-homogeneous solid/liquid reaction, which can be described by two stages from kinetic point of view. At the earlier stage, reaction rate is so fast that its kinetic course is intricate, which requires further study. At the latter stage, the rate of reaction becomes slow and the process of reaction accords with one order reaction kinetic equation. Experimental results show that the relationship between reaction rate constant k1 and temperature T accords to Arrhenius Equation, and the activation energy of sorption （Ea） is 11.93 kJ/mol and frequency factor （A） is 2.51 s^-1. X-ray diffraction （XRD）, scanning electron microscopy with an energy dispersive X-ray fluoresence spectrometer （SEM-EDS） and toxicity characteristic leaching procedure （TCLP） test were conducted in this work. It is indicated that the main mechanism is dissolution-precipitation, accompanying with superficial sorption.
文摘Nanocrystal carbonated hydroxyapatite was prepared by lecithin-controlled chemical precipitation in synthetic body fluid （SBF）. The reactant was aged and heated at 850℃ for crystallization. The morphology and microstructure of the carbonated hydroxyapatite were investigated using transmission electron microscope （TEM）, X-ray diffraction （ XRD ） and FTIR. The experimental results demonstrate that the shapes of carbonated hydroxyapdtite particles display spheres with the average size of 20- 28 nm, and carbonated hydroxyapatite contained carbonate ions, similar to mineral of bone tissues.
文摘The mixture of CaHPO 4·2H 2O and CaCO 3 was ground in an aqueous system under appropriate conditions to investigate the mechanochemical reaction for the synthesis of crystalline hydroxyapatite (HA) powder. Hydroxyapatite of high crystallinity powder including trace Ca 10 (PO 4) 6CO 3(OH) and Ca 9HPO 4(PO 4) 6OH can be synthesized by mechanical activation without further thermal treatment at a high temperature. The synthesis reaction during the grinding process was almost completed within 1h. The as-ground powder exhibits a particle distribution of 20-100nm in size with a spherical or rodlike morphology. The composition and degree of crystallinity of the mechanochemical synthesized hydroxyapatite powders were coincident with the cement-type hydroxyapatite.
基金the National Natural Science Foundation of China(Nos.52275393 and 51935014)Hunan Provincial Natural Science Foundation of China(Nos.2021JJ20061,2020JJ3047,and 2019JJ50588)+4 种基金Jiangxi Provincial Natural Science Foundation of China(No.20224ACB204013)the Project of State Key Laboratory of High Performance Complex ManufacturingTechnology Innovation Platform Project of Shenzhen Institute of Information Technology 2020(No.PT2020E002)Guangdong Province Precision Manufacturing and Intelligent Production Education Integration Innovation Platform(No.2022CJPT019)Independent Exploration and Innovation Project of Central South University(No.1053320220553).
文摘Bacterial infection is a major problem following bone implant surgery.Moreover,poly-l-lactic acid/carbon nanotube/hydroxyapatite(PLLA/CNT/HAP)bone scaffolds possess enhanced mechanical properties and show good bioactiv-ityregardingbonedefectregeneration.Inthisstudy,wesynthesizedsilver(Ag)-dopedCNT/HAP(CNT/Ag-HAP)nanohybrids via the partial replacing of calcium ions(Ca2+)in the HAP lattice with silver ions(Ag+)using an ion doping technique under hydrothermal conditions.Specifically,the doping process was induced using the special lattice structure of HAP and the abundant surface oxygenic functional groups of CNT,and involved the partial replacement of Ca2+in the HAP lattice by doped Ag+as well as the in situ synthesis of Ag-HAP nanoparticles on CNT in a hydrothermal environment.The result-ing CNT/Ag-HAP nanohybrids were then introduced into a PLLA matrix via laser-based powder bed fusion(PBF-LB)to fabricate PLLA/CNT/Ag-HAP scaffolds that showed sustained antibacterial activity.We then found that Ag+,which pos-sesses broad-spectrum antibacterial activity,endowed PLLA/CNT/Ag-HAP scaffolds with this activity,with an antibacterial effectiveness of 92.65%.This antibacterial effect is due to the powerful effect of Ag+against bacterial structure and genetic material,as well as the physical destruction of bacterial structures due to the sharp edge structure of CNT.In addition,the scaffold possessed enhanced mechanical properties,showing tensile and compressive strengths of 8.49 MPa and 19.72 MPa,respectively.Finally,the scaffold also exhibited good bioactivity and cytocompatibility,including the ability to form apatite layers and to promote the adhesion and proliferation of human osteoblast-like cells(MG63 cells).
基金Support by the National Natural Science Foundation of China(21276225,21476196)
文摘Scaffolds with multimodal pore structure are essential to cells differentiation and proliferation in bone tissue engineering. Bi-/multi-modal porous PLGA/hydroxyapatite composite scaffolds were prepared by supercritical C02 foaming in which hydroxyapatite acted as heterogeneous nucleation agent. Bimodal porous scaffolds were prepared under certain conditions, i.e. hydroxyapatite addition of 5%, depressurization rate of 0.3 MPa. min-1, soaking temperature of 55 ℃, and pressure of 9 MPa. And scaffolds presented specific structure of small pores （122 μM ± 66 μm） in the cellular walls of large pores （552 μm ±127 μm）. Furthermore, multimodal porous PLGA scaffolds with micro-pores （37 μM ± 11μM） were obtained at low soaking pressure of 7.5 MPa. The interconnected porosity of scaffolds ranged from （52.53 ± 2.69）% to （83.08±2.42）% by adjusting depressurization rate, while compression modulus satisfied the requirement of bone tissue engineering. Solvent-free CO2 foaming method is promising to fabricate bi-/multi-modal porous scaffolds in one step, and bioactive particles for osteogenesis could serve as nucleation agents.
文摘Hydroxyapatite(HA)and its composites with inorganic additives,dopants,and polymers is a rapidly developing branch in the materials chemistry.In particular,carbon allotropes are widely used in these composites being widely applied for medical purposes.Observing a gap of insufficient generalization of recent achievements in the field of the HA/Carbon composites,in this review we present the state of the art of the field of HA composites and hybrids with classic carbon allotropes and nanocarbons.These composites are known for carbon nanotubes,nanofibers,graphene and its oxidized forms,as well as,in a lesser grade,for graphite,fullerenes,nanodiamonds,carbon nanofoams,etc.These composites can be fabricated by a variety of classic and less-common methods,such as co-precipitation(with or without ultrasonic treatment),CVD,hot isostatic pressing,hydrothermal,spark plasma sintering,biomimetic mineralization,thermal and plasma spray,electrochemical and electrophoretic deposition,self-assembling,3D printing,electrospinning,and lyophilisation,among others.Combination of various synthesis techniques can be also carried out for composite preparation.Natural or synthetic HA can be used as it is for further interaction with carbon allotropes or it can be first prepared and then reacted with carbon counterpart;similarly,carbon allotropes can be introduced into the interaction with HA directly or they can be first synthesized,in particular from biomass.Resulting biocompatible composites can be produced in the form of coatings,powders,and scaffolds and can additionally contain quantitative amounts of third phases,frequently natural or synthetic polymers.In these composites,especially with O-containing functionalizing groups,HA disadvantages could be considerably decreased with simultaneous enhancement of mechanical properties,becoming similar to human bone,chemical stability and biocompatibility,as well as possessing antibacterial effect.GO→G reduction and higher HA decoration were observed in several experiments.The morphology of polymer-containing HA/GO composites can be tuned by variations of GO:polymer ratios.Predominant number of resulting applications of formed HA composites corresponds to the biomedical area,mainly for orthopedic applications/implants,osteoporosis treatment,myocardial,skin and dental regeneration,etc.Other important uses include applications as adsorbents for the elimination of impurities from wastewaters and/or removal/uptake of heavy metal cations,loading several medicines,and energy storage materials.Biocompatibility and hemocompatibility aspects of HA/Carbon composites are also discussed and future developments are proposed.
