Calcium phosphate fiber was synthesized by homogeneous precipitation method using urea as precipitation agent. Effects of the reactant concentration and hydrothermal temperature on the calcium phosphate morphology and...Calcium phosphate fiber was synthesized by homogeneous precipitation method using urea as precipitation agent. Effects of the reactant concentration and hydrothermal temperature on the calcium phosphate morphology and composition were studied using SEM, FTIR and XRD. It is found that fine octacalcium phosphate（OCP）fiber can be synthesized when the reactant concentrations are 0.167 mol/L for Ca（NO3）2, 0.1 mol/L for （NH4）2HPO4, and 0.6-0.7 mol/L for （NH2）2CO, respectively, with the initial reactant solution pH value around 2.2, hydrothermal temperature 90 ℃ and termination reaction at pH value around 5.0. At very low urea concentration, the product size distribution is highly inhomogeneous, however, at an excessively high concentration the product becomes larger and shorter and a mixture of OCP and hydroxyapatite （HA）. Increasing the hydrothermal temperature is favorable to the fast precipitation of OCP, higher productivity and finer product.展开更多
Dissolution of the (100) face of octacalcium phosphate (OCP) single crystal in weak acidic solutions (pH = 6.5;25°C) was observed in situ using atomic force microscopy. Monomolecular steps (2.0 nm high) were o...Dissolution of the (100) face of octacalcium phosphate (OCP) single crystal in weak acidic solutions (pH = 6.5;25°C) was observed in situ using atomic force microscopy. Monomolecular steps (2.0 nm high) were observed;they originated from etch pits or crystal edges. Advancement of the dissolution process led to precipitation of nanoparticles as small as ~10 nm even though the solution was undersaturated with respect to OCP. This precipitation of nanoparticles was accompanied by a drastic decrease in the dissolution rate;however, the substrate OCP continued to dissolve, indicating that dissolution and growth occurred simultaneously on the same surface. The precipitated nanoparticles coalesced and eventually covered the entire surface without changing the surface morphology of the substrate crystal. The step height after complete coverage was ~2.0 nm, the same as that observed on the dissolving OCP surface. These findings indicate that the precipitated phase was a pseudomorph of OCP crystal.展开更多
Investigation of thermostability will lead the groundbreaking of unraveling the mechanism of influence of ion-doping on the properties of calcium phosphates.In this work,octacalcium phosphate(OCP),a metastable precurs...Investigation of thermostability will lead the groundbreaking of unraveling the mechanism of influence of ion-doping on the properties of calcium phosphates.In this work,octacalcium phosphate(OCP),a metastable precursor of biological apatite,was used as a stability model for doping ions(Fe^(3+)and Sr^(2+))with different ionic charges and radii.After treated under hot air at different temperatures(110-200◦C),the phase,morphology,structure,physicochemical properties,protein affinity,ions release,and cytological responses of the ion-doped OCPs were investigated comparatively.The results showed that the collapse of OCP crystals gradually occurred,accompanying with the dehydration of hydrated layers and the disintegration of plate-like crystals as the temperature increased.The collapsed crystals still retained the typical properties of OCP and the potential of conversion into hydroxyapatite.Compared to the undoped OCP,Fe-OCP,and Sr-OCP had lower and higher thermostability respectively,leading to different material surface properties and ions release.The adjusted thermostability of Fe-OCP and Sr-OCP significantly enhanced the adsorption of proteins(BSA and LSZ)and the cytological behavior(adhesion,spreading,proliferation,and osteogenic differentiation)of bone marrow mesenchymal stem cells to a varying extent under the synergistic effects of corresponding surface characteristics and early active ions release.This work paves the way for understanding the modification mechanism of calcium phosphates utilizing ion doping strategy and developing bioactive OCP-based materials for tissue repair.展开更多
Lanthanum(La)has tremendous potential in the treatment and prevention of bone diseases especially osteoporosis and metabolic disorders.However,controlling its distribution and keeping the release of La^(3+)ions sustai...Lanthanum(La)has tremendous potential in the treatment and prevention of bone diseases especially osteoporosis and metabolic disorders.However,controlling its distribution and keeping the release of La^(3+)ions sustained and steady in the body is still a big challenge.In this study,we prepared La-OCP powders via co-precipitation method,and further prepared La-OCP/PLA porous scaffolds by 3 D printing.La^(3+)was successfully introduced into the OCP crystal structure and substituted Ca^(2+)at the Ca-5 and Ca-8 sites.In particular,some La^(3+)ions were deposited on the crystal surface in the form of nanoparticles.Both octacalcium phosphate(OCP,Ca_(8)H_(2)(PO_(4))_6·5 H_(2)O)crystals and nanoparticles played as the carriers for La^(3+)ions.The La-OCP/PLA scaffolds displayed obvious mineralization effects and sustained release of La^(3+).The scaffolds contained a uniform structure with rough micro surface topography which acted as a suitable pathway for BMSCs cells to adhere,grow and proliferation.At a certain La^(3+)concentration,the extracts from La-OCP/PLA scaffolds increased the expression of osteogenesis-related genes,thus promoting the osteogenic differentiation of BMSCs.Moreover,the extracts regulated the immune responses.The experiment in vivo proved that La-OCP/PLA porous scaffolds were safe and could enhance bone defect regeneration in vivo.These findings suggest that 3 D printed La-OCP/PLA porous scaffolds have promising potentials in bone tissue engineering.展开更多
In the present study, the Pulsed Laser Deposition (PLD) technique was applied to coat titanium for orthopaedicand dental implant applications. Calcium carbonate (CC) was used as starting coating material.The deposited...In the present study, the Pulsed Laser Deposition (PLD) technique was applied to coat titanium for orthopaedicand dental implant applications. Calcium carbonate (CC) was used as starting coating material.The deposited CC films were transformed into octacalcium phosphate (OCP) by chemical treatments. Theresults of X-ray diffraction (XRD), Raman, Fourier Transform Infrared Spectroscopy (FTIR) and scanningelectron microscopy (SEM) studies revealed that the final OCP thin films are formed on the titaniumsurface. Human myofibroblasts from peripheral vessels and the primary bone marrow mesenchymalstromal cells (BMMSs) were cultured on the investigated materials. It was shown that all the investigatedsamples had no short-term toxic effects on cells. The rate of division of myofibroblast cells growing onthe surface and saturated BMMSs concentration for the OCP coating were about two times faster than ofcells growing on the CC films.展开更多
When calcium phosphate forms in soft tissues such as blood vessels and heart valves, it causes disease. The abnormal formation of calcium phosphate is called pathogenic mineralization or pathogenic calcification. Cas...When calcium phosphate forms in soft tissues such as blood vessels and heart valves, it causes disease. The abnormal formation of calcium phosphate is called pathogenic mineralization or pathogenic calcification. Cases of rheumatic heart disease （RHD） always occur with fibrotic and calcified tissue of heart valve. In this article, samples taken from calcified human heart wdves were studied. The characterization was performend by scanning electronic microscope, X-ray Diffraction and transmission electron microscopy with selective diffraction patterns. It is found for the first time that calcium phosphate grains existing in the calcified human heart valves contain octacalcium phosphate （ OCP ）.展开更多
基金Funded by the Guangzhou Municipal Science and Technology Bureau(No. 2008J1-C101)supported in part by the National Natural Science Foundation of China (No. 50803019)the Doctoral Program of Ministry of Education of China (No. 200805611030)
文摘Calcium phosphate fiber was synthesized by homogeneous precipitation method using urea as precipitation agent. Effects of the reactant concentration and hydrothermal temperature on the calcium phosphate morphology and composition were studied using SEM, FTIR and XRD. It is found that fine octacalcium phosphate（OCP）fiber can be synthesized when the reactant concentrations are 0.167 mol/L for Ca（NO3）2, 0.1 mol/L for （NH4）2HPO4, and 0.6-0.7 mol/L for （NH2）2CO, respectively, with the initial reactant solution pH value around 2.2, hydrothermal temperature 90 ℃ and termination reaction at pH value around 5.0. At very low urea concentration, the product size distribution is highly inhomogeneous, however, at an excessively high concentration the product becomes larger and shorter and a mixture of OCP and hydroxyapatite （HA）. Increasing the hydrothermal temperature is favorable to the fast precipitation of OCP, higher productivity and finer product.
文摘Dissolution of the (100) face of octacalcium phosphate (OCP) single crystal in weak acidic solutions (pH = 6.5;25°C) was observed in situ using atomic force microscopy. Monomolecular steps (2.0 nm high) were observed;they originated from etch pits or crystal edges. Advancement of the dissolution process led to precipitation of nanoparticles as small as ~10 nm even though the solution was undersaturated with respect to OCP. This precipitation of nanoparticles was accompanied by a drastic decrease in the dissolution rate;however, the substrate OCP continued to dissolve, indicating that dissolution and growth occurred simultaneously on the same surface. The precipitated nanoparticles coalesced and eventually covered the entire surface without changing the surface morphology of the substrate crystal. The step height after complete coverage was ~2.0 nm, the same as that observed on the dissolving OCP surface. These findings indicate that the precipitated phase was a pseudomorph of OCP crystal.
基金supported by the National Natural Science Foundation of China(Grant 31800791)the Natural Science Foundation of Guangdong Province(Grant 2018030310062)the Fundamental Research Funds for the Central Universities(Grant 21620427).
文摘Investigation of thermostability will lead the groundbreaking of unraveling the mechanism of influence of ion-doping on the properties of calcium phosphates.In this work,octacalcium phosphate(OCP),a metastable precursor of biological apatite,was used as a stability model for doping ions(Fe^(3+)and Sr^(2+))with different ionic charges and radii.After treated under hot air at different temperatures(110-200◦C),the phase,morphology,structure,physicochemical properties,protein affinity,ions release,and cytological responses of the ion-doped OCPs were investigated comparatively.The results showed that the collapse of OCP crystals gradually occurred,accompanying with the dehydration of hydrated layers and the disintegration of plate-like crystals as the temperature increased.The collapsed crystals still retained the typical properties of OCP and the potential of conversion into hydroxyapatite.Compared to the undoped OCP,Fe-OCP,and Sr-OCP had lower and higher thermostability respectively,leading to different material surface properties and ions release.The adjusted thermostability of Fe-OCP and Sr-OCP significantly enhanced the adsorption of proteins(BSA and LSZ)and the cytological behavior(adhesion,spreading,proliferation,and osteogenic differentiation)of bone marrow mesenchymal stem cells to a varying extent under the synergistic effects of corresponding surface characteristics and early active ions release.This work paves the way for understanding the modification mechanism of calcium phosphates utilizing ion doping strategy and developing bioactive OCP-based materials for tissue repair.
基金financially supported by the National Natural Science Foundation of China(No.82072074)the National Natural Science Foundation of China(No.51801198)+2 种基金funds of Scientific and Technological Plan of Fujian Province(No.2020Y0083)the Natural and Science Foundation of Fujian Province(No.2019I0027)the Funds of Scientific and Technological Plan of Fujian Province(No.2020L3026)。
文摘Lanthanum(La)has tremendous potential in the treatment and prevention of bone diseases especially osteoporosis and metabolic disorders.However,controlling its distribution and keeping the release of La^(3+)ions sustained and steady in the body is still a big challenge.In this study,we prepared La-OCP powders via co-precipitation method,and further prepared La-OCP/PLA porous scaffolds by 3 D printing.La^(3+)was successfully introduced into the OCP crystal structure and substituted Ca^(2+)at the Ca-5 and Ca-8 sites.In particular,some La^(3+)ions were deposited on the crystal surface in the form of nanoparticles.Both octacalcium phosphate(OCP,Ca_(8)H_(2)(PO_(4))_6·5 H_(2)O)crystals and nanoparticles played as the carriers for La^(3+)ions.The La-OCP/PLA scaffolds displayed obvious mineralization effects and sustained release of La^(3+).The scaffolds contained a uniform structure with rough micro surface topography which acted as a suitable pathway for BMSCs cells to adhere,grow and proliferation.At a certain La^(3+)concentration,the extracts from La-OCP/PLA scaffolds increased the expression of osteogenesis-related genes,thus promoting the osteogenic differentiation of BMSCs.Moreover,the extracts regulated the immune responses.The experiment in vivo proved that La-OCP/PLA porous scaffolds were safe and could enhance bone defect regeneration in vivo.These findings suggest that 3 D printed La-OCP/PLA porous scaffolds have promising potentials in bone tissue engineering.
基金This work was supported by the Russian Science Foundation(project N15-19-00078)Authors are grateful to Mr.M.Ortenzi,G.De Santis and G.Emma for technical support and assistance.
文摘In the present study, the Pulsed Laser Deposition (PLD) technique was applied to coat titanium for orthopaedicand dental implant applications. Calcium carbonate (CC) was used as starting coating material.The deposited CC films were transformed into octacalcium phosphate (OCP) by chemical treatments. Theresults of X-ray diffraction (XRD), Raman, Fourier Transform Infrared Spectroscopy (FTIR) and scanningelectron microscopy (SEM) studies revealed that the final OCP thin films are formed on the titaniumsurface. Human myofibroblasts from peripheral vessels and the primary bone marrow mesenchymalstromal cells (BMMSs) were cultured on the investigated materials. It was shown that all the investigatedsamples had no short-term toxic effects on cells. The rate of division of myofibroblast cells growing onthe surface and saturated BMMSs concentration for the OCP coating were about two times faster than ofcells growing on the CC films.
文摘When calcium phosphate forms in soft tissues such as blood vessels and heart valves, it causes disease. The abnormal formation of calcium phosphate is called pathogenic mineralization or pathogenic calcification. Cases of rheumatic heart disease （RHD） always occur with fibrotic and calcified tissue of heart valve. In this article, samples taken from calcified human heart wdves were studied. The characterization was performend by scanning electronic microscope, X-ray Diffraction and transmission electron microscopy with selective diffraction patterns. It is found for the first time that calcium phosphate grains existing in the calcified human heart valves contain octacalcium phosphate （ OCP ）.
