湿法制备羟基磷灰石生物活性陶瓷粉末的热力学分析

本文对制备羟基磷灰石的Ｃａ（ＮＯ３）２－（ＮＨ４）２ＨＰＯ４－ＮＨ４ＯＨ－Ｈ２ＯＬ体系进行热力学分析。计算求得ＨＡ沉淀最宜ｐＨ条件为１０．６－１２．４，热力学计算与实验结果和文献报告数据结果一致。     

模拟体液法快速合成羟基磷灰石纳米针

采用模拟体液法快速制备羟基磷灰石（HA）纳米针,并研究了HA生长机制。分析结果表明,仅反应lmin就可以获得宽约5nm,长50-80nm且分散良好的HA纳米针,形貌和尺寸与人体骨中的HA极为相似。反应时间影响合成产物的形貌及物相,短时间内延长反应时间有利于HA纳米针的生长,但反应时间超过48h会导致HA与过量的HPO4,2-反应生成Ca3（PO4）2。     

纳米羟基磷灰石粉体的水热合成

采用Ca(NO3)2·4H2O和(NH4)3PO4·3H2O作为反应前驱物,通过水热合成颗粒尺寸在100nm以下的短棒状或针状HA晶体.X射线衍射(XRD)、透射电镜(TEM)和红外光谱(FTIR)分析讨论水热温度、反应时间、表面活性剂和烧结与物相组成、晶粒尺寸和晶体形貌的关系.实验结果表明升高反应温度和延长反应时间有利于HA的生成;表面活性剂有助于改善粉体的分散性能;烧结能提高晶体的结晶程度,但粉体易团聚,当温度高于800℃时HA发生分解.     

掺杂铈的纳米羟基磷灰石的合成

本研究的主要目的是探讨掺杂铈的纳米羟基磷灰石的合成及其结构。本实验在反应原料中以不同的 X_(Ce)=Ce/(Ca Ce)(摩尔比)引入铈离子(范围在0%到10%),采用了水热法合成掺杂铈的纳米羟基磷灰石。用 TEM、EDS、XRD 和 FTIR 对合成产物的微观形貌、化学成分和晶体结构进行分析表征。分析结果表明 Ce~(3 )可进入羟基磷灰石晶格中,置换其中的 Ca~(2 );颗粒尺寸能随着 X_(Ce)的增大而变大,当 X_(Ce)≤5%时全是纳米级的颗粒。总而言之,本实验证明利用水热法可合成成分纯且分布均匀的掺杂铈的纳米羟基磷灰石是可行的。     

微波法制备纳米羟基磷灰石的研究进展

羟基磷灰石是人体骨骼的主要无机成分，具有良好的生物相容性和生物活性，能与新生骨形成很强的化学键合，是植入生物陶瓷材料研究的重点物质之一。微波烧结具有快速加热，能量利用率高，操作简便，过程易于控制等特点，被誉为“21世纪新一代烧结技术”。综述了微波烧结的基本原理，以及国内外微波法制备纳米羟基磷灰石的研究进展，提出了有待解决的问题。     

超声化学法合成羟基磷灰石纳米棒

在37℃下的模拟体液中采用超声化学法制备羟基磷灰石(HA)纳米棒,研究了初始pH值和反应时间对合成磷酸钙产物晶相的影响.结果发现在初始pH＜7.5时产物为无水磷酸氢钙相和HA相的混合物,初始pH值≥7.5时产物为单一的HA相,延长超声波处理时间有利于羟基磷灰石晶相的生成,最佳的反应参数为初始pH≥7.5,反应时间在6h以上.利用TEM、FTIR对HA相产物进行表征发现,HA为含碳酸根羟基磷灰石,其形貌长度为200nm,直径为10～30nm的纳米棒,其在组成和形态上与生物体内的磷灰石相十分接近.     

溶胶状态纳米羟基磷灰石的制备

在溶胶状态下制备羟基磷灰石，进行对比实验，讨论分散剂的作用。对合成的羟基磷灰石样品进行了红外光谱分析，X多晶衍射分析和电镜分析。结果：得到椭球状纳米级羟基磷灰石。不同于传统的粉末制品，具有更广阔的应用前景。     

超声化学法合成纳米羟基磷灰石粉体的研究

以Ca(NO3)2和(NH4)2HPO4为原料,应用超声化学法制备得到了尺寸约20nm×120nm、分散性良好的针状羟基磷灰石(HAp)纳米粉体.对比研究了超声化学法与传统的化学沉淀法对HAp粉体的结晶性能、Ca/P摩尔比和产率的影响.研究表明,与传统的化学沉淀法相比,超声化学法可以在较短的时间内显著地提高纳米HAp的合成效率、结晶度、Ca/P摩尔比和产率.     

生物羟基磷灰石的合成

综述了生物羟基磷灰石合成研究的最新进展，重点介绍和评述了羟基磷灰石的合成与制备方法，讨论了各种方法的特点和应用前景。最新的研究动态表明，羟基磷灰石研究从基本的化学反应合成向生物矿化与新生骨引导机理及硬组织再造技术方向发展。同时，羟基磷灰石在金属、陶瓷等植入体表面的涂层、以及天然材料制备羟基磷灰石依然是其合成研究的主要方向。     

羟基磷灰石纳米棒的合成及其体外生物活性研究

在没有任何表面活性剂存在的情况下，利用水热法合成了尺寸分布均匀的羟基磷灰石（HAp）纳米棒，其长度和直径分别为0．5～1．51am和45～60nm。通过模拟体液（SBF）浸泡实验，研究了其体外生物活性。结果显示，浸泡10d后的羟基磷灰石纳米棒直径变为60～140nm，表面有新的羟基磷灰石层的形成，表明了该羟基磷灰石纳米棒具有良好的生物活性．     

Optimization of sol-gel technique for coating of metallic substrates by hydroxyapatite using the Taguchi method

In this study, the Taguchi method of design of experiment (DOE) was used to optimize the hydroxyapatite (HA) coatings on various metallic substrates deposited by sol-gel dip-coating technique. The experimental design consisted of five factors including substrate material (A), surface preparation of substrate (B), dipping/withdrawal speed (C), number of layers (D), and calcination temperature (E) with three levels of each factor. An orthogonal array of L₁₈ type with mixed levels of the control factors was utilized. The image processing of the micrographs of the coatings was conducted to determine the percentage of coated area (PCA). Chemical and phase composition of HA coatings were studied by XRD, FT-IR, SEM, and EDS techniques. The analysis of variance (ANOVA) indicated that the PCA of HA coatings was significantly affected by the calcination temperature. The optimum conditions from signal-to-noise (S/N) ratio analysis were A: pure Ti, B: polishing and etching for 24 h, C: 50 cm min^?1, D: 1, and E: 300 °C. In the confirmation experiment using the optimum conditions, the HA coating with high PCA of 98.5 % was obtained.     

Barium hydroxyapatite nanoparticles synthesized by citric acid sol-gel combustion method

Barium hydroxyapatite (BaHAP) nanoparticles have been synthesized by citric acid sol-gel combustion method using citric acid as a reductant/fuel and nitrate as an oxidant at a relatively low temperature of 600 °C. The thermal decomposition of nitrate-citrate xerogel was investigated by thermogravimetric/differential thermal analysis (TG/DTA) technique. The yielding powders calcined at 600 °C have been characterized by Fourier transform infrared (FT-IR), X-ray diffraction (XRD), and transmission electron microscope (TEM). The possible combustion process was presented.     

非水溶剂溶胶-凝胶法制备纳米SnO2

以乙二醇为溶剂、SnCl4·5H2O为原料用溶胶凝胶法制备了SnO2粉体材料.用X射线衍射和透射电子显微镜对材料进行了检测和表征,所得SnO2粉末具有良好的分散性,最小晶粒粒径为9.5nm.探讨了初始反应物浓度和聚合温度对晶粒粒径的影响.     

玻璃基生物骨水泥内部纳米羟基磷灰石的形成研究

以CaO-SiO2-P2O5系统生物玻璃和磷酸铵调和液混合制得玻璃基生物骨水泥(GBC),利用XRD、FTIR和SEM对GBC的产物晶相、化学组成和内部显微结构进行了分析,并对其力学性能进行了测试。实验结果表明,随着浸泡时间的增加GBC中的玻璃相逐步向羟基磷灰石(HAP)微晶转化,生成的磷灰石为弱结晶度的类骨状碳酸羟基磷灰石微晶,这些微晶主要分布于玻璃粉末的界面之间,端面尺寸在30～50nm,这表明GBC中所生成的HAY晶体与人体骨有很大的相似性,因而会具有良好的生物活性。对力学性能测试的结果表明,随着浸泡时间的增加GBC的抗压强度逐步增加,在30天时可达到80MPa。因而GBC不仅具有良好的生物活性,而且具有一定的力学强度。     

Evaluation and characterization of nanostructure hydroxyapatite powder prepared by simple sol-gel method

Many attempts have been focused on preparing of synthetic hydroxyapatite (HA), which closely resembles bone apatite and exhibits excellent osteoconductivity. Low temperature formation and fusion of the apatite crystals have been the main contributions of the sol-gel process in comparison with conventional methods for HA powder synthesis. This paper describes the synthesis of nano-HA particles via a sol-gel method. Nanocrystalline powder of hydroxyapatite (HA) was prepared using Ca(NO₃)₂·4H₂O and P₂O₅ by a simple sol-gel approach. X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used for characterization and evaluation of the phase composition, morphology and particle size of products. The presence of amorphous and crystalline phases in the as-dried gel precursor was confirmed by the evaluating technique. Single phase of HA was also identified in the heat treated powder by XRD patterns. SEM and TEM evaluations showed that the obtained powder after heat treatment at 600 °C was agglomerated and composed of nanocrystalline (25-28 nm) HA particles. Increasing the sintering temperature and time could cause decomposition of HA into β-tricalcium phosphate and calcium oxide. The prepared nanocrystalline HA is able to improve the contact reaction and the stability at the artificial/natural bone interface for medical applications.     

A combined chitosan/nano-size hydroxyapatite system for the controlled release of icariin

Icariin, a plant-derived flavonol glycoside, has been proved as an osteoinductive agent for bone regeneration. For this reason, we developed an icariin-loaded chitosan/nano-sized hydroxyapatite (IC–CS/HA) system which controls the release kinetics of icariin to enhance bone repairing. First, by Fourier transform infrared spectroscopy, we found that icariin was stable in the system developed without undergoing any chemical changes. On the other hand, X-ray diffraction, scanning electron microscopy and mechanical test revealed that the introduction of icariin did not remarkably change the phase, morphology, porosity and mechanical strength of the CS/HA composite. Then the hydrolytic degradation and drug release kinetics in vitro were investigated by incubation in phosphate buffered saline solution. The results indicated that the icariin was released in a temporally controlled manner and the release kinetics could be governed by degradation of both chitosan and hydroxyapatite matrix. Finally the in vitro bioactivity assay revealed that the loaded icariin was biologically active as evidenced by stimulation of bone marrow derived stroma cell alkaline phosphatase activity and formation of mineralized nodules. This successful IC–CS/HA system offers a new delivery method of osteoinductive agents and a useful scaffold design for bone regeneration.     

Synthesis and sintering of nanocrystalline hydroxyapatite powders by citric acid sol-gel combustion method

The citric acid sol-gel combustion method has been used for the synthesis of nanocrystalline hydroxyapatite (HAP) powder from calcium nitrate, diammonium hydrogen phosphate and citric acid. The phase composition of HAP powder was characterized by X-ray powder diffraction analysis (XRD). The morphology of HAP powder was observed by transmission electron microscope (TEM). The HAP powder has been sintered into microporous ceramic in air at 1200 °C with 3 h soaking time. The microstructure and phase composition of the resulting HAP ceramic were characterized by scanning electron microscope (SEM) and XRD, respectively. The physical characterization of open porosity and flexural strength have also been carried out.     

A new sol-gel route using inorganic salt for synthesizing Al2O3 nanopowders

Boehmite (γ-AlOOH) powder was first prepared by sol-freeze drying method using inexpensive AlCl₃.6H₂O as raw material, and then γ-Al₂O₃ nanopowder with average diameter of 6 nm and α-Al₂O₃ nanopowder with mean diameter of 30 nm were obtained by the calcination of the above γ-AlOOH powder at 500 °C and 1100 °C, respectively. Potential-pH diagrams of Al-H₂0 system at 25 °C and 90 °C were obtained, separately. Thermodynamic analysis of the main reactions in the process of thermal decomposition of Al(OH)₃ was also made using Temkin-Schwarzman's method and by means of regression analysis. Investigations of the potential-pH diagrams of Al-HO system and the thermodynamic analysis of thermal decomposition of Al(OH)₃ provide a guide to the formation of boehmite sol and heat treatment of boehmite powder, respectively.     

Synthesis of hydroxyapatite nanopowders by sol-gel emulsion technique

Hydroxyapatite nanopowders were synthesized by a sol-gel emulsion technique by varying the concentration of a non-ionic surfactant in the organic phases (oil phase) of water-in-oil (w/o) emulsion. Calcium acetate dissolved in distilled water and phosphorous pentoxide dissolved in 2-butanol were used as starting precursors. The prepared sol was emulsified in a support solvent (cyclohexane) containing 2, 4 and 5 volume% of surfactant (Span 80), followed by the addition of triethylamine, for gelation. The gel powders thus obtained were calcined at different temperatures up to 750??C. Characterization was done using XRD, SEM and TEM. Pellets were made from the developed HAP powders and tested for its biocompatibility after their immersion in the simulated body fluid.     

Crystallization kinetics of sol-gel derived hydroxyapatite thin films

The crystallization kinetics of sol-gel derived hydroxyapatite (HA) and tricalcium phosphate (TCP) thin films were studied to determine whether viscous sintering could be used for densification. The films were approximately 900 nm thick, and were synthesized and processed on silicon substrates. The films were fired in air in a rapid thermal annealer (RTA) for various times and the degree of crystallinity was determined by measuring the intensity of characteristic X-ray diffraction lines. The growth kinetics of HA and TCP were measured between 420 and 550 °C, and between 840 and 920 °C, respectively. Films that were subjected to an accelerated aging step before firing, exhibited a significantly lower crystallization growth rate when compared to unaged films. The aged films also became harder, as measured by nanoindentation. At temperatures above 840 °C, HA transformed into both -and -TCP, with the form being dominant at lower temperatures. The activation energies for both transformations (amorphous film to HA, and HA to TCP) were determined, as were the constants for the Avrami equation. Based on the rapid crystallization kinetics observed for the amorphous film to HA transformation, densification through viscous sintering is essentially precluded in this system. © 2001 Kluwer Academic Publishers