可注射nano HA/PAG/CS复合材料的制备与表征

通过原位聚合法制备了可注射纳米羟基磷灰石/天门冬氨酸-谷氨酸共聚物/硫酸钙复合材料(HA/PAG/CS), 采用FTIR、XRD、SEM对复合材料的组成结构、表面形貌及力学性能进行了表征, 研究了复合材料在模拟体液(SBF)中的降解性能。结果显示: 复合材料无机相羟基磷灰石、硫酸钙与有机相天门冬氨酸-谷氨酸共聚物之间存在化学相互作用, 具有良好的抗压强度; 7周后, 复合材料在SBF中完全降解, 降解方式为表面降解; 在降解过程中, 浸泡液的pH值在6.4~7.4之间变化; 复合材料在SBF中浸泡后, 其表面能够沉积磷灰石, 表明复合材料具有良好的生物活性, 有利于植入体与骨组织形成良好的界面结合。     

Apatite wollastonite–poly methyl methacrylate bio-composites

Bio-composites consisting of sol–gel processed apatite wollastonite (AW) glass ceramics and poly methyl methacrylate (PMMA) were prepared by hot compaction method. Density of the composites decreased with increase in PMMA content, while, biaxial flexural strength (BFS) was 21 MPa for 20 wt.% PMMA and beyond which it decreased. A correlation between phase compositions of AW glass ceramics with BFS was attempted from the XRD results. In vitro bioactivity of the composites in a simulated body fluid (SBF) showed the formation of spherical globules on the surface within 7 days of soaking as observed by environmental SEM. Thin film XRD and EDX measurement confirmed these globules to be bone like apatite with Ca/P ratio 1.53 and FTIR measurement showed the corresponding peaks for phosphates. Results indicated the bone bonding ability of the composites by forming a surface apatite (calcium phosphate) layer in SBF and the growth increased with increase in soaking durations. ICP measurement of the remaining SBF after 7, 14 and 21 days soaking of samples was found to be in good agreement with the EDX analysis results.     

Effect of thermal treatment on apatite-forming ability of NaOH-treated tantalum metal

The prerequisite for an artificial material to bond to living bone is the formation of bonelike apatite on its surface in the body. This apatite can be reproduced on its surface even in an acellular simulated body fluid with ion concentrations nearly equal to those of the human blood plasma. The present authors previously showed that the tantalum metal subjected to a NaOH treatment to form a sodium tantalate hydrogel layer on its surface forms the bonelike apatite on its surface in SBF in a short period. The gel layer as-formed on the metal is, however, not resistant against abrasion, and hence thus-treated metal is not useful for clinical applications. In the present study, effects of thermal treatment on the mechanical properties and apatite-forming ability of the NaOH-treated tantalum metal were investigated. The sodium tantalate gel on the NaOH-treated tantalum was dehydrated to convert into amorphous sodium tantalate by a thermal treatment at 300 °C in air environment and into crystalline sodium tantalates by the thermal treatment at 500 °C. Resistivity of the gel layer against both peeling-off and scratching was significantly improved by the thermal treatment at 300 °C. The high apatite-forming ability of the sodium tantalate hydrogel was a little decreased by the thermal treatment at 300 °C, but appreciably decreased by the thermal treatment at 500 °C. It is believed that the tantalum metal subjected to the 0.5 M-NaOH treatment and the subsequent thermal treatment at 300 °C is useful as implants in dental and orthopaedic fields, since it shows high bioactivity as well as high fracture toughness. © 2001 Kluwer Academic Publishers     

Relationship between apatite-forming ability and mechanical properties of bioactive PMMA-based bone cement modified with calcium salts and alkoxysilane

Polymethylmethacrylate (PMMA)-based bone cement is used for the fixation of artificial joints in orthopaedics. However, the fixation is liable to loosen in the body, because the cement does not bond to living bone. So-called bioactive ceramics bond directly to living bone through the apatite layer formed on their surfaces in the body. We previously revealed that modification using γ-methacryloxypropyltrimethoxysilane (MPS) and water-soluble calcium salts such as calcium acetate and calcium hydroxide was effective for providing the PMMA-based bone cement with apatite-forming ability in a simulated body fluid (SBF, Kokubo solution) that closely reproduces the body environment. However, the effect of the chemical reaction forming the apatite on the mechanical properties of the cements has not been clarified. The present work aimed to investigate this issue from the viewpoint of the interface structure between the apatite and the cement. The surface of the cement modified with calcium acetate and MPS was fully covered with newly formed apatite after soaking in Kokubo solution within 7 days, while half of the surface area of the cement modified with calcium hydroxide and MPS was covered with the apatite. The bending strength of the modified cements decreased after soaking in Kokubo solution. Porous structure was observed in the region about 50–100 μm in depth from the top surface because of release of the Ca²⁺ ions by both modified cements after soaking in Kokubo solution. The decrease in bending strength of the modified cements could be attributed to the formation of the pores. In addition, the pores on the top surfaces of the cements were filled with the newly formed apatite. The apatite formation would be effective not only for bioactivity but also for decreasing the reduction of mechanical strength.     

真空和大气等离子喷涂镁黄长石生物活性涂层的对比研究

大气喷涂法制备的镁黄长石涂层是一种具有优良生物活性的新型骨科移植体涂层材料, 但其结晶度较低, 影响涂层的化学稳定性。本研究采用真空等离子喷涂法在钛合金表面制备了高结晶度的镁黄长石涂层。与大气喷涂镁黄长石涂层相比, 真空喷涂镁黄长石涂层具有更高的磷灰石矿化能力, 在SBF中浸泡6 d后表面即沉积了一层类骨磷灰石层, 浸泡14 d后表面沉积的磷灰石层的厚度约为大气涂层的4倍。真空喷涂镁黄长石涂层的离子释放明显低于大气涂层, 显示出更高的化学稳定性。骨髓间充质干细胞在真空和大气喷涂镁黄长石涂层表面粘附和铺展良好, 在两种涂层表面的增殖速度均明显高于HA涂层。本研究表明真空等离子喷涂的镁黄长石陶瓷涂层因其显著提高的生物活性及化学稳定性, 可能更适合用作人工关节涂层材料。     

磷酸氢钙/氨基酸共聚物生物活性复合材料

通过原位聚合法制备了磷酸氢钙/四元氨基酸共聚物(DCP/PAA)复合材料, 并采用XRD和IR方法对其组成结构进行了表征, 用模拟体液和Tris-HCl溶液分别研究了复合材料的体外生物活性和降解性能。结果表明: DCP/PAA复合材料的无机相与有机相存在着一定的相互作用; 聚合反应时间对复合材料的强度有明显的影响, 反应时间越长, PAA的黏度越大, 材料的抗压强度越高; 复合材料具有很好的生物活性, 其表面能够在模拟体液中形成磷灰石层, 新形成磷灰石的Ca与P原子比为1.59, 为缺钙磷灰石; 复合材料能够在Tris-HCl溶液中降解, PAA的黏度对复合材料在Tris-HCl中的降解有一定的影响。复合材料浸泡在Tris-HCl溶液中, 溶液的pH值在浸泡初期略有下降, 但4周后稳定在7.0~7.2, 与人体环境pH值接近。     

Hydroxyapatite/Bioactive Glass Films Produced by a Sol–Gel Method: In Vitro Behavior

Hydroxyapatite (HA) and HA/bioactive glass (49S) films were deposited on Si(100) substrates by a sol–gel dip‐coating method. The microstructure and in vitro bioactivity of the films were investigated by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and X‐ray photoelectron spectroscopy (XPS). Polycrystalline HA and amorphous bioactive glass films were obtained after annealing at 600 and 400 °C, respectively. The crystallization temperature of HA was determined to be around 568 °C. The surfaces of the HA films were covered with an apatite layer consists of spherulites formed by nanosized needle‐like aggregates after the soaking in simulated body fluid (SBF) for 10 days, while amorphous HA/bioactive glass surface was covered with larger spherical crystallites. Both XPS and EDS results obtained from HA/bioactive glass film, after soaking in SBF, showed increasing P amounts on the surface at the expense of Si. The higher density of the newly formed layer on HA/bioactive glass surface than that of the HA surface after 10 days of soaking was evidence of increased reaction rate and apatite forming ability when bioactive glass layer is present on the HA films.     

New chemical treatment for bioactive titanium alloy with high corrosion resistance

It was recently claimed that titanium metal and its alloys can bond to the living bone, without being coated by apatite (VPS coatings), but by being chemically and heat-treated. The bioactivity of treated titanium is of interest because of the opportunity to obtain orthopaedic or dental implants presenting, at the same time, high toughness, strength and fatigue resistance as well as bone-bonding ability. The bioactive behaviour of the treated implants is due to the presence of a modified surface, which, during soaking in body fluid, promotes the precipitation of apatite. The apatite formed is strongly bonded to the substrate and promotes living bone bonding. In this work were characterised samples of Ti-6Al-7Nb alloy with surfaces presenting a different chemical and mechanical state. The aim of the research was twofold. The first objective was to characterise chemically and heat-treated samples with different surface topography, in order to define the best conditions for osteogenic integration. The second aim was to assess the corrosion behaviour of the bioactive implants, because they expose a microporous and quite thin modified surface layer. No-treated and passivated samples, with a surface state closed to that nowadays used on implants, were used as reference. The surface structure, morphology, electrochemical behaviour and bioactivity of the different samples were assessed by means of XRD, SEM-EDS, anodic polarizations, open circuit measurements and in-vitro tests. Results evidence that it is possible to modify the surface of the Ti-6Al-7Nb alloy in order to obtain the formation of a bioactive layer and that the substrate roughness influences the characteristics of the surface layer formed. It was also evidenced that the as treated surfaces present inadequate corrosion behaviour, so a new two-step chemical treatment has been developed in order to obtain a bioactive material with good corrosion resistance.     

钛合金表面K2Ti6O13w涂层的制备及其生物活性

K2Ti6O13晶须不仅具有优越的力学性能和良好的生物学特性,而且具有与常规Ti合金相近的膨胀系数。本研究尝试选用K2Ti6O13晶须（K2Fi6O13w）作为生物活性涂层材料,利用BCC方法（混合-包埋-煅烧）在Ti合金基体上成功制备了K2Ti6O13w涂层,并对涂层的表面形态、结合强度和生物活性进行了研究。结果表明,涂层由K2Ti6O13晶须和少量的TiO2和K2Ti6O9组成,其表面粗糙多孔。由于膨胀系数的良好匹配,涂层与基体之间具有较高的结合强度,达24MPa。模拟体液培养后,涂层表面沉积了一层多孔的骨状羟基磷灰石,它由平均直径20nm,长200nm的羟基磷灰石纳米线组成,这表明钛酸钾涂层具有良好的生物活性。涂层较高的生物活性与其独特的生化特性和组分密切相关。     

In vitro degradation of novel bioactive polycaprolactone—20% tricalcium phosphate composite scaffolds for bone engineering

Our group recently fabricated novel 3D polycaprolactone—20% tricalcium phosphate (PCL-TCP) composite scaffolds for applications in bone engineering. The bioactivity of such synthetic biomaterials can be evaluated by examining its ability to initiate the formation of apatite on its surface when immersed in simulated body fluids (SBF). In this study, the in vitro degradation behaviors of these scaffolds were systematically monitored for varying time periods of 1, 7, 14, 21 and 28 days post-immersion in SBF at 37 °C. Weight loss and water absorption of the samples indicated that PCL-TCP scaffolds were only slowly degraded. Biochemical assays and pH measurements revealed that hydroxyapatite, the main inorganic constituent of bone, commenced to form on the surface of the scaffolds after 17 days of immersion in SBF. Von Kossa assays demonstrated that calcium deposits increased progressively on the surface of the scaffolds after soaking in SBF for 2 weeks. Scanning electron microscopy verified the surface crystallization of the apatite layer formed over the entire period of time. In conclusion, the synergy of PCL with TCP in a composite scaffold confers both bioresorbability as well as bioactivity that offer an exciting approach for bone regeneration purposes.     

Bioactivity of zirconia nanotube arrays fabricated by electrochemical anodization

Zirconia nanotubes with a diameter of 50 nm and a length of 20 μm were fabricated by anodic oxidation of zirconium in (NH₄)₂SO₄ electrolyte containing NH₄F. The structure and phase composition of the zirconia nanotube layers were characterized by scanning electron microscopy (SEM), transmission electron microscope (TEM) and X-ray diffraction (XRD). The bioactivity was assessed by investigating the formation of apatite on the surface of zirconia nanotubes after soaking in simulated body fluids (SBF) for 20–30 days. The results indicate that bone-like apatite can be formed on the surface of the zirconia nanotube layers in our SBF immersion experiments. Microstructure of zirconia nanotubes with apatite layer was observed by SEM. Substance and phase compositions were characterized respectively by energy dispersive X-ray spectrometer (EDS) and XRD. Our results show that zirconia nanotube layers fabricated by electrochemical anodization exhibit favorable bioactivity.     

Formation mechanism of biomedical apatite coatings on porous titania layer

A titania containing calcium and phosphate with rough and porous structure was prepared by microarc oxidation. The in vitro bioactivity was examined by immersing the samples into the simulated body fluid (SBF). And the mechanism was also discussed. The results show that only 3 days of immersion in SBF, apatite was formed on the surface, and after 6 days, nearly all the surface covered by apatite. This indicates that the layer can induce the formation of apatite in simulated body fluid. It is analyzed that the key factors of the apatite formation are the hydrolysis of the CaTiO₃ and special structure.     

等离子体喷涂氧化钛涂层的生物活性研究

以纳米TiO₂粉末为喷涂原料, 采用大气等离子体喷涂技术在医用钛合金上制备氧化钛涂层. 利用酸和碱溶液对氧化钛涂层表面进行生物活化处理, 体外模拟体液浸泡实验考察涂层的生物活性. 采用XRD、SEM、FTIR、EDS等测试技术对改性前后氧化钛涂层的生物活性进行表征. 结果表明: 氧化钛涂层和钛合金基体的结合强度较高, 其值高达40MPa, 涂层的耐模拟体液腐蚀性优于钛合金. 酸和碱溶液表面改性后的氧化钛涂层经模拟体液浸泡可在其表面生成含有碳酸根的羟基磷灰石(类骨磷灰石), 显示良好的生物活性.     

The formation of a hydroxyl bond and the effects thereof on bone-like apatite formation on a magnesia partially stabilized zirconia (MgO–PSZ) bioceramic following CO2 laser irradiation

For the purpose of improving the bioactivity of a magnesia partially stabilized zirconia (MgO-PSZ) and to explore a new technique for inducing OH group and apatite formation, a CO(2) laser has been used to modified the surface properties. The bioactivity of the CO(2) laser modified MgO-PSZ has been investigated in stimulated human fluids (SBF) with ion concentrations almost equal to those in human blood plasma. Some hydroxyl groups were found on the MgO-PSZ following CO(2) laser treatment with selected power densities. The surface melting on the MgO-PSZ induced by CO(2) laser processing provides the Zr(4+) ion and OH(-) ion, in turn, the incorporation of the Zr(4+) ion and the OH(-) ion creates the Zr-OH group on the surface. After 14 days of SBF soaking, the apatites formed on the MgO-PSZ with relatively high amount of hydroxyl groups generated by the CO(2) laser treatment, while no apatite was observed on the untreated with few hydroxyl groups. It exhibits that the Zr-OH groups on the MgO-PSZ surface is the functional groups to facilitate the apatite formation. The increased surface roughness provides more active sites, meantime, increased surface energy benefits to the adsorption and reaction on the surface.     

Fabrication of bioactive composite by developing PLLA onto the framework of sintered HA scaffold

Composite porous scaffolds of hydroxyapatite (HA)/poly-l-lactide (PLLA) were fabricated by a two-step immersing replication method. Structure and mechanical properties of both the single HA scaffold and the composite HA/PLLA scaffold were determined. The bioactivity of the scaffolds was evaluated by soaking in a simulated body fluid (SBF), and the formation of the apatite layer was determined by X-ray diffraction (XRD), Scanning Electron Microscope (SEM) and Energy-Dispersive Spectrometer (EDS). The results showed that without changing the highly interconnected porous structure, the HA/PLLA composite scaffold was mechanically enhanced to a great deal of extent compared with single HA scaffold. On the other hand, it is also suggested that the HA/PLLA scaffold was bioactive as it induced the formation of apatite on the surface of the composite scaffolds after soaking in SBF for 7 days.     

Low-temperature deposition of rutile film on biomaterials substrates and its ability to induce apatite deposition in vitro

Low-temperature deposition of crystalline titania films on intrinsically bioinert materials to induce the bioactivity is of practical interest, not only because it meets the demand of providing organic biomaterials with bioactivity, which cannot tolerate high-temperature thermal treatments, but also because it reserves abundant Ti–OH groups facilitating the apatite deposition. In this paper, rutile films with thickness varied from 0.1 μm to 1.7 μm were deposited on commercially available pure titanium substrates from 1.5 M titanium tetrachloride aqueous solution kept at 60 °C for 3–60 h. The rutile films grew to give a preferred (101) crystalline plane in the X-ray diffraction pattern. After soaking in a simulated body fluid of the Kokubo solution (SBF) for 2 days, the rutile films with thickness over 0.6 μm were covered with a layer of apatite. All the films with various thickness induced apatite deposition in SBF after soaking for 5 days. The bioinert polytetrafluoroethylene (PTFE) was also found to exhibit remarkable in vitro bioactivity as to induce apatite deposition from SBF within 2 days, after depositing the rutile film on the surface. This work is supported partly by the Natural Science Foundation of Zhejiang Province under the project No. M503011.     

In vitro apatite formation on polyamide containing carboxyl groups modified with silanol groups

Modification of organic polymer with silanol groups in combination with calcium salts enables the polymer to show bioactivity, that is, the polymer forms apatite on its surface after exposure to body environment. However, how modification with silanol groups influences ability of apatite formation on the polymer substrate and adhesive strength between polymer and apatite is not yet known. In the present study, polyamide containing carboxyl groups was modified with different amounts of silanol groups, and its apatite-forming ability in 1.5SBF, which contained ion concentrations 1.5 times those of simulated body fluid (SBF), was examined. The rate of apatite formation increased with increasing content of silanol groups in the polyamide films. This may be attributed to enhancement of dipole interactions. A tendency for the adhesive strength of the apatite layer on the polyamide film to be decreased with increasing content of silanol groups was observed. This may be attributed to swelling in 1.5SBF and having a high degree of shrinkage after drying. These findings clearly show that modification of organic polymers with the functional groups induces apatite deposition, and also determines the adhesive strength of the apatite layer to the organic substrates.     

Surface modification of cp-Ti using femtosecond laser micromachining and the deposition of Ca/P layer

Femtosecond laser processing is employed to create regular patterns and bioactive layer on the surface of pure titanium. Surface morphology and microstructure of the laser-processed layer are characterized by scanning electron microscope (SEM) and transmission electron microscope (TEM). The results show that the processing with varied laser energies builds a surface with three-order roughness from nanometer scale to micrometer scale. Selected area electron diffraction indicates that some kind of TiO layer emerges on the surface after femtosecond laser machining. The bioactivity of TiO layer is further evaluated by soaking it in simulated body fluid (SBF). SEM observation and EDX analysis show that Ca/P layer is rapidly formed on the surface of TiO layer after SBF soaking. It implies that TiO layer with unique three-order roughness has good bioactivity.     

通过仿生法在硅橡胶表面制备磷灰石薄膜的研究

用CaCl2的乙醇溶液和K2HPO4溶液对硅橡胶进行预处理,将处理过的硅橡胶分别浸渍于模拟体液和钙磷饱和溶液中来制备磷灰石薄膜.利用薄膜X射线衍射、红外吸收光谱和扫描电子显微镜对形成的薄膜进行了表征.结果表明,分别在模拟体液中7d和在钙磷饱和溶液中5d后,硅橡胶表面形成了一层磷灰石薄膜;在模拟体液中的薄膜表面呈网状并分布有许多球状晶粒,在钙磷饱和溶液中的薄膜为结晶良好的片状晶体.     

Apatite mineralization abilities and mechanical properties of covalently cross-linked pectin hydrogels

Natural bone has features such as high fracture toughness and bone-bonding bioactivity, and is organic–inorganic hybrid composed of collagen and apatite crystals. Therefore, apatite-polymer hybrids designed to mimic the structure of bone represent candidates for high-performance bone substitutes. In this study, we prepared pectin hydrogels through covalent cross-linking using divinylsulfone (DVS) and investigated their apatite-forming abilities of the gels in simulated body fluid (SBF) and mechanical properties by tensile test. The obtained results were interpreted in terms of surface charge of the gels and chemical reaction with SBF. The apple- and citrus-derived gels formed the apatite on their surfaces in SBF within 3 days. These gels showed tensile strength around 30 MPa.