Synthesis of a Hydroxyapatite/Collagen/Chondroitin Sulfate Nanocomposite by a Novel Precipitation Method

A hydroxyapatite/collagen/chondroitin sulfate nanocomposite that partly mimicked the composition of cartilage was synthesized through a novel precipitation method, using a calcium hydroxide suspension and phosphoric acid solutions that contained several mixing ratios of type II collagen (Col) and chondroitin sulfate (ChS). The precipitates were shaped and consolidated via filter pressing and subsequent cold isostatic pressing, respectively. A preferential alignment of the crystallographic c -axis of the hydroxyapatite nanocrystals along the longitudinal direction of the Col and ChS mixture was observed. The fracture strength and Vickers hardness of the nanocomposites were in the ranges of 35–50 and 119–219 MPa, respectively. This nanocomposite may be applicable for use as a bone substitute, because of its potential capability of bone remodeling through endochondral ossification.     

Nucleation of Hydroxyapatite Crystal through Chemical Interaction with Collagen

The nucleation of hydroxyapatite (HAp) crystal through chemical interaction with collagen was investigated. A collagen membrane was soaked in a supersaturated simulated body fluid (1.5 SBF) solution with ion concentrations at 1.5 times that of normal simulated body fluid (1.0 SBF). A few carbonate-containing HAp crystals were formed mostly on the edge-side of the collagen membrane after 4 weeks. In the Fourier-transform infrared spectometry (FTIR) results, the carboxylate band of the collagen membrane showed red chemical shifts after the formation of HAp crystals, which coincided well with the decrease of the calculated bond orders of the carboxylate group when chelated with a calcium ion, which emulated the first-step nucleation of HAp crystal on the carboxylate group of collagen. The result implies that the binding of a calcium ion to the carboxylate group of collagen is one of the key factors for the nucleation of HAp crystals in a 1.5 SBF solution.     

Increasing the Crystallinity of Hydroxyapatite Nanoparticles in Composites Containing Bioaffinitive Organic Polymers by Mechanical Stressing

Crystallinity of hydroxyapatite (HAp) in bioaffinitive disperse systems was increased by a wet mechanochemical treatment at room temperature. Silk fibroin (SF) and/or hyaluronic acid (HYA) were used as bioorganics. With the mechanochemical treatment, the crystallite size and the aspect ratio of HAp decreased and became closer to that of swine trabecular bone. Mechanochemical effects on the HAp nanocrystals were discussed in terms of coherent chemical interaction between HAp and bioorganics.     

Molten Salt Synthesis of Calcium Hydroxyapatite Whiskers

Calcium hydroxyapatite (HA) whiskers and crystals were produced by the route of molten salt synthesis. The effects on whisker morphology of chosen flux, flux-to-HA ratio, synthesis temperature, and reaction time were investigated. The thermal stabilities of the produced whiskers were tested at 1300°C in an air atmosphere. A tentative X-ray diffraction pattern was proposed for the HA whiskers. Molten salt synthesis with a K₂SO₄ flux was found to be a simple and sturdy technique for manufacturing short (≤60 μm) HA whiskers in the temperature range from 1080° to ∼1200°C. The alternative use of fluxes such as KCl, KBr, CaCl₂, or Na₂SO₄, rather than K₂SO₄, over the temperature range 850°–1000°C resulted in the formation of large (∼25 μm) single crystals of HA.     

超声处理对羟基磷灰石纳米针状晶形成的影响

实验采用液相沉淀法以硝酸钙和磷酸氢二铵为原料，以水为溶剂，以氨水为调节剂。采用不同的工艺条件(反应物浓度和分散剂种类)制备了羟基磷灰石，然后对试样进行超声处理。研究了制备工艺条件对所获纳米针状晶体在形态和生长上影响。     

Effect of Silicon Substitution on the Sintering and Microstructure of Hydroxyapatite

The substitution of between 0 and 1.6 wt% silicon (Si-HA) in hydroxyapatite (HA) inhibited densification at low temperatures (1000°–1150°C), with these effects being more significant as the level of silicon substitution was increased. For higher sintering temperatures (1200°–1300°C), the sintered densities of HA and Si-HA compositions were comparable. Examination of the ceramic microstructures by scanning electron microscopy (SEM) showed that silicon substitution also inhibited grain growth at higher sintering temperatures (1200°–1300°C). The negative effect of silicon substitution on the sintering of HA at low temperatures (1000°–1150°C) was reflected in the hardness values of the ceramics. However, for higher sintering temperatures, e.g., 1300°C, where sintered densities were comparable, the hardness values of Si-HA compositions were equal to or greater than that of HA, reflecting the smaller grain sizes observed for the former.     

层状溶致液晶中纳米羟基磷灰石的合成

在一定的pH值条件下,将Ca(NO3)2和(NH4)2HPO4分别溶于C34H62O11(聚乙二醇辛基苯基醚)/C8H17OH/H2O体系层状溶致液晶溶剂层中,混合并经陈化即可在溶剂层中生成具有一定微观形貌的羟基磷灰石纳米粒子(HA),其直径可以达到10 nm,长度在100 nm以下.产物在不同温度下焙烧,分别用FTIR,XRD和TEM等对产物的结构及形貌进行分析表征.对不同反应物浓度条件下所得HA的微观形貌进行分析对比,并提出了改善团聚的有效措施.     

Uniaxial Hydroxyapatite Growth on a Self-Assembled Protein Scaffold

Biomineralization is a crucial process whereby organisms produce mineralized tissues such as teeth for mastication, bones for support, and shells for protection. Mineralized tissues are composed of hierarchically organized hydroxyapatite crystals, with a limited capacity to regenerate when demineralized or damaged past a critical size. Thus, the development of protein-based materials that act as artificial scaffolds to guide hydroxyapatite growth is an attractive goal both for the design of ordered nanomaterials and for tissue regeneration. In particular, amelogenin, which is the main protein that scaffolds the hierarchical organization of hydroxyapatite crystals in enamel, amelogenin recombinamers, and amelogenin-derived peptide scaffolds have all been investigated for in vitro mineral growth. Here, we describe uniaxial hydroxyapatite growth on a nanoengineered amelogenin scaffold in combination with amelotin, a mineral promoting protein present during enamel formation. This bio-inspired approach for hydroxyapatite growth may inform the molecular mechanism of hydroxyapatite formation in vitro as well as possible mechanisms at play during mineralized tissue formation.     

羟基磷灰石抗菌剂的研究

采用正交设计方法,以羟基磷灰石作为载体,银离子和铈离子作为抗菌离子,采用离子交换方法制备羟基磷灰石抗菌剂,考察了硝酸银浓度、反应时间、反应温度和硝酸铈浓度等因素.运用X射线衍射谱研究了影响羟基磷灰石抗菌剂的微观结构;运用抑菌圈法表征所制备的抗菌剂的抗菌性能.研究表明:硝酸银浓度为0.2 mol/L、反应温度为30℃、反应时间为3 h和硝酸铈浓度为0.01 mol/L时对羟基磷灰石抗菌效果最好.     

温度和pH值对羟基磷灰石粉体合成的影响

用液相沉淀法制备羟基磷灰石粉体,研究了温度和pH值对羟基磷灰石粉体合成的影响,结果表明:制备的羟基磷灰石粉体纯度较高,随着温度的增加其晶化程度增加,当pH值等于4.5,9和12.4时,制备的粉体分别为β-Ca2P2O7,HA+β-TCP和HA.TEM结果表明:羟基磷灰石沉淀颗粒形态呈针状或条状,其直径约10～20nm,长约100～200nm,当羟基磷灰石粉体加热至900℃时,颗粒发生团聚,晶粒长大,其尺寸约为200～400nm.     

六氟磷酸对含氟羟基磷灰石薄膜形成的影响

含氟羟磷灰石薄膜在生物、抗菌和发光材料方面有着重要的应用前景。采用Ca(NO3) 2 和P2 O5的乙醇溶液为先驱体 ,六氟磷酸(HPF6 )作为氟引入剂 ,3者形成混合物 ,保持Ca与P的摩尔比为 1.67,经回流后作为涂膜液。通过浸渍涂膜法和 60 0℃热处理 ,在玻璃和钛合金基板上形成氟含量不同的含氟磷灰石薄膜。采用XRD ,XPS ,SEM ,FTIR ,紫外 -可见光谱方法对薄膜进行了表征。实验结果显示HPF6 是一种非常有效的氟引入剂 ,不仅能改变薄膜中的氟含量 ,适量加入时还可以明显改善薄膜的微观均匀性     

活性磷酸钙微观形貌对SAN悬浮聚合的影响

活性磷酸钙作为悬浮聚合的分散剂,在苯乙烯-丙烯腈共聚物(SAN)聚合体系中对聚合产物形貌粒径有重要影响。对活性磷酸钙(HAP)进行扫描电镜观察,发现不同来源的HAP表面形貌有较大差异。将这几种活性磷酸钙作为分散剂用于苯乙烯-丙烯腈共聚物(SAN)的悬浮聚合。对比聚合产物的粒子形貌及粒径分布,发现当HAP微观形貌为均匀竹叶形或棒状,且堆积松散时得到的聚合物粒子外观规整,粒径分布均匀。     

水热条件下针状羟基磷灰石单晶体的均相合成

用水热法制备出结晶度高、纯净均一的针状羟基磷灰石单晶体。从X-射线衍射谱、红外吸收光谱、透射电镜分析等方面确认了所得晶体为羟基磷灰石单晶体。根据透射电子衍射谱测量计算出的晶面间距d值与羟基磷灰石卡片的d值非常接近,由标定的晶面指数计算出的晶面夹角与实际测量值有很好的吻合,从而确定所得晶体为单晶。     

羟基磷酸钙的制备及其对甲基丙烯酸甲酯悬浮聚合的影响

利用Ca(OH)2和H3PO4中和反应制备悬浮聚合分散剂超细羟基磷酸钙(HAP). 通过正交实验法,研究了反应温度、Ca(OH)2浓度、H3PO4滴加速度、表面活性剂十二烷基苯磺酸钠(SDBS)的加入量等各因素对反应产物羟基磷酸钙结晶形态与尺寸的影响. 分别将不同条件下制备的HAP与聚乙烯醇(PVA)组成复合分散体系,通过甲基丙烯酸甲酯(MMA)的悬浮聚合反应,比较了各组的聚合效果. 应用红外光谱及透射电镜对HAP进行了表征,分析了HAP的结晶形态及尺寸对聚甲基丙烯酸甲酯(PMMA)的粒径及其分布的影响. 结果表明,本实验制备的长′宽为140 nm×35 nm的针状结晶HAP与PVA的复合分散体系对MMA悬浮聚合效果最好,可制备出综合性能较好、粒径d32达1.41 mm的PMMA光学小球.     

硫酸软骨素A对草酸钙晶体生长和聚集的影响

用体外模拟方法研究了硫酸软骨素 A(简称 C4S)对草酸钙晶体矿化热力学的影响 ,并对纯水体系和 C4S- H2 O体系中形成的草酸钙晶体进行了物相分析与形貌观察。发现 C4S不但在热力学过程中有利于提高溶液中 Ca2 + 存在的浓度 ,而且能诱导一水草酸钙 ( COM)晶体的 ( 1 0 1 )晶面优先生长 ,并抑制 COM的二维生长和聚集。     

明胶/羟基磷灰石复合物微球中明胶对无机相影响的研究

在油包水的乳液体系中,通过原位合成的方法使羟基磷灰石(HAP)在明胶链上化学沉积,改变明胶溶液的浓度,制得了一系列的明胶/HAP复合物微球.采用X射线衍射仪(XRD)、傅里叶变换红外光谱仪(FTIR)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)和热失重分析仪(TGA)等对产物的组成、形貌以及热失重情况进行了表征.结果表明,明胶用量对复合物微球中HAP的形成具有重要影响.在明胶溶液浓度为0.025 g/mL时,明胶分子链提供的结合位点恰好与溶液中游离的Ca2+、PO43-等离子达到平衡状态,复合物微球中无机相含量达40%,这是明胶与HAP以化学键合的形式结合所能得到的最大值.     

Hydrothermal Formation of Hydroxyapatite Layers on the Surface of Type-A Zeolite

Type-A zeolite evenly covered with hydroxyapatite thin layers was prepared using hydrothermal treatment at 120°C for 8 h under autogenous pressure. The hydroxyapatite needlelike nanocrystals, 100–200 nm in diameter and 30 nm in thickness, were grown under the reaction between discharged Ca²⁺ ions from type-A zeolite and PO₄³⁻ ions in (NH₄)₃PO₄ solution. The preferential orientations of the c -axis of hydroxyapatite crystals perpendicular to a zeolite surface were observed using transmission electron microscopy. The crystal structure of type-A zeolite was not destroyed under the reaction, but the surface morphology was changed only with complete covering of scaly hydroxyapatite particles.     

含硅羟基磷灰石的研究进展

含硅羟基磷灰石(Si-HA),即硅酸根替代了一部分的磷酸根进入羟基磷灰石的晶格中,从而显著的提高了羟基磷灰石的生物活性.本文综述了含硅羟基磷灰石的各种制备工艺以及硅的掺入对羟基磷灰石性能的影响,并对Si-HA未来的发展前景进行了分析.     

羟基磷灰石生物陶瓷涂层制备方法评述

根据医用生物陶瓷羟基为磷灰石及医用金属材料的生物，力学特性，本文认为在金属基体表面涂覆羟基磷灰石是综合金属材料及生物陶瓷材料各自优越性阳有希望的途径这一。评述了羟基磷灰石涂层的制备方法，论证了较为优化的涂层结构。     

羟基磷灰石和贝壳对水泥水化和抗侵蚀性能的影响

沿海水泥混凝土工程长期受到腐蚀,很难达到预期服役寿命.本文分析其中的原因,希望采用水泥混凝土表面生长海洋生物的方法来抵抗腐蚀.研究羟基磷灰石、贝壳和碳酸钙对硅酸盐42.5R水泥和硫铝酸盐水泥抗硫酸盐侵蚀性能的影响.结果表明:硅酸盐水泥和硫铝酸盐水泥中掺人适萤的羟基磷灰石、贝壳和碳酸钙时,其抗侵蚀系数有一定程度增加.当硫铝酸盐水泥中碳酸钙掺量为10%时,其抗侵蚀系数为1.16,硅酸盐水泥中碳酸钙掺量为15%时,其抗侵蚀系数达到1.34,抗硫酸盐侵蚀能力最强.硅酸盐水泥和硫铝酸盐水泥中掺入羟基磷灰石时,其水化放热量比掺碳酸钙和掺贝壳的水化放热量低,且在硅酸盐水泥中掺入混合材料后,水泥的水化放热量低于硅酸盐的水化放热量,这有利于提高水泥混凝土工程的耐久性.