羟基磷灰水热法可控制备的研究

羟基磷灰石具有生物活性和生物相容性，因此，羟基磷灰石的合成及控制研究是当今生物材料领域研究的重要热点．水热合成法是实现高纯HAP制备的有效方法，然而，单一的合成方法很难实现HAP结构及大小有效控制．综述了近几年来水热合成法与其它方法联合实现HAP结构、大小的有效控制，以及近年来纳米羟基磷灰石制备的最新研究进展，并讨论制备条件对HAP结构及大小的影响及形成机理。     

钛合金表面涂覆羟基磷灰石的研究进展

在钛合金表面制备羟基磷灰石涂层既有良好的生物相容性又兼有良好的力学性能,作为硬组织替换材料得到了广泛的研究.总结了钛合金表面涂覆羟基磷灰石的生物相容性,详细讨论了羟基磷灰石涂层的制备方法,总结和展望了该生物涂层材料在医学中的应用所存在的问题和应用前景.     

生物可吸收储存式药物控释载体制备研究

针对骨科疾病治疗中传统的用药方式存在的问题,研究制备了一种生物可吸收靶向式药物控释载体。首先在体外模拟天然骨的生物矿化过程,利用材料的自组装机制合成了羟基磷灰石／胶原类骨仿生复合材料,再采用热致分相／非溶剂抽提成孔技术进一步与聚乳酸复合制备了三维多孔储存式药物控释载体。通过对材料的表征和模型化合物控释实验,结果显示羟基磷灰石／胶原复合材料与天然骨类似,羟基磷灰石／胶原／聚乳酸储存式载体能达到控制释放的目的。     

羟基磷灰石生物涂层的复合制备与生物相容性

采用等离子喷涂CaHPO4和水热处理复合制备羟基磷灰石生物涂层,研究了羟基磷灰石涂层的结合强度和溶解性,用成骨细胞考察了生物相容性,结果表明,喷涂涂层由C aHPO4,β－Ca2P2O7和α-C3(PO4)2组成,其相比例,结晶性和形貌取决于喷涂电流和喷涂距离;喷涂涂导经过水热处理可转化为针状结晶的缺钙羟基磷灰石,这种羟基磷灰石涂层具有高的结合强度和稳定性,与成骨细胞的生物相容性良好。     

纳米羟基磷灰石粉体及其与PEEK复合材料的制备

以CaCl2和H3PO4为先驱体,在150℃、pH为9~10的条件下,水热4h制得了纳米羟基磷灰石(HA)粉体。采用X-射线衍射、红外光谱仪、透射电子显微镜等手段对样品进行了表征。研究表明,粉体颗粒c轴方向尺寸为60~100nm,a轴方向尺寸为20~30nm,与人骨中的HA尺寸较为接近。采用注射成型法,将纳米羟基磷灰石(HA)与聚醚醚酮(PEEK)复合,制备出PEEK-HA生物复合材料,并采用拉伸试验和硬度测量检测了材料的力学性能。结果表明,适量纳米羟基磷灰石的加入以及热处理可以改善复合材料的力学性能。     

纳米羟基磷灰石的制备方法与应用

介绍了羟基磷灰石的组成、性质、结构以及在生物材料和其他方面的应用,在讨论纳米羟基磷灰石的主要几种合成方法的同时,对各种方法和制备工艺的优缺点进行分析,提出了改进的方向。     

电泳沉积制备羟基磷灰石／生物玻璃梯度涂层的研究

本文研究了羟基磷灰石颗料，生物玻璃颗粒在醋酸介质中的电泳沉积规律，利用它们不同的沉积规律设计了羟基磷灰石／生物玻璃梯度沉积装置，用电子探针分析了涂层横截面元素分布，表明所设计的装置可实现羟基磷灰石和生物玻璃的梯度涂层。     

超声辅助湿法合成纳米HA及MWNT/HA复合材料

以Ca(NO3)2·4H2O、(NH4)2HPO4和NH3·H2O为原料,在超声波辅助下,湿法合成了羟基磷灰石,用FTIR、XRD和TEM对产物进行了分析,结果表明:合成的羟基磷灰石为纳米级纺缍状晶体,不用烧结即具有较高晶化度,且为单一的羟基磷灰石晶相。以此制备条件为基础,采用原位合成的方法制备了多壁碳纳米管/羟基磷灰石复合材料,FTIR、XRD和TEM的分析结果表明:碳纳米管能较好的分散于羟基磷灰石基体中,部分碳纳米管表面可被反应生成的羟基磷灰石所包覆,二者之间有着较好的相容性,可作为一种新型的生物复合材料应用。     

羟基磷灰石/ 胶原类骨仿生复合材料的制备及表征

通过体外模拟天然骨生物矿化和材料自组装的形成机制, 研究制备了类骨羟基磷灰石/ 胶原仿生复合材料并对材料进行了表征。结果表明: 纳米羟基磷灰石均匀分布在胶原基质上并择优取向排列, 该复合材料的成分和微观结构与天然骨类似。      

快速温和有效的壳聚糖生物矿化方法探讨

研究利用快速、温和、有效的生物矿化方法制备了壳聚糖纳米羟基磷灰石杂化海绵材料。在矿化过程中使用乙醇-水混合溶剂来控制纳米羟基磷灰石晶体的相变、生长及形态,利用尿素的分解来控制体系的pH值。通过XRD、TEM、FT-IR和SEM对海绵结晶、组成及形貌进行了表征,通过压缩强度测试检测了矿化前后海绵的力学强度变化。结果表明高结晶度和取向度的羟基磷灰石晶体能够迅速有效地沉积在壳聚糖海绵的表面,并且力学强度显著提高,压缩强度和压缩模量分别达到(2.42±0.006)和(29.29±1.25)MPa。本矿化方法可以推广到其它天然生物材料及器械的生物矿化。     

Recent advances in synthesis, characterization of hydroxyapatite/polyurethane composites and study of their biocompatible properties

The development of engineered biomaterials that mimic bone tissues is a promising research area that benefits from a growing interest. Polymers and polymer–ceramic composites are the principle materials investigated for the development of synthetic bone scaffolds thanks to their proven biocompatibility and biostability. Several polymers have been combined with calcium phosphates (mainly hydroxyapatite) to prepare nanocomposites with improved biocompatible and mechanical properties. Here, we report the hydrothermal synthesis in high pressure conditions of nanostructured composites based on hydroxyapatite and polyurethane functionalized with carboxyl and thiol groups. Cell-material interactions were investigated for potential applications of these new types of composites as coating for orthopedic implants. Physical–chemical and morphological characteristics of hydroxyapatite/polyurethane composites were evaluated for different compositions, showing their dependence on synthesis parameters (pressure, temperature). In vitro experiments, performed to verify if these composites are biocompatible cell culture substrates, showed that they are not toxic and do not affect cell viability.     

Synthesis of a novel silica/apatite mesoporous nanocomposite

A novel mesoporous MCM-41/hydroxyapatite material is developed based on the co-precipitation of hydroxyapatite and silica. Mesoporosity is induced by the use of surfactant templating. Two ways of synthesis route are examined. One of the synthesis procedures leads to the formation of the hydroxyapatite covered by amorphous silica; while the other one results in obtaining the sample characterized by a high specific surface area (in comparison with pure hydroxyapatite) and narrow, uniform mesopores. In both samples the existence of hydroxyapatite was confirmed using the XRD method. The structural parameters, as well as silica and hydroxyapatite coexistence, promise potential biological applications of the coprecipitated nanocomposite.     

Hydrothermal synthesis and nanostructure of carbonated calcium hydroxyapatite

The influence of precursor concentration, pressure, temperature and time of hydrothermal synthesis on the development of calcium hydroxyapatite structure has been analyzed. The obtained results show that it is possible to adjust the conditions of hydrothermal synthesis from solutions of relatively high concentrations to obtain calcium hydroxyapatite nanopowders of well-defined structure. The relationship between the synthesis and the lattice parameters, as well as the crystallite size and the microstructure of synthesized hydroxyapatite has been established. The synthesized powders are preferentially carbonated hydroxyapatite of the B type in the form of agglomerates that accommodate two-modal size pores of 1.5–10 and 50–200 nm. The structure of calcium hydroxyapatite particles consists of crystallites 8–22 nm in size, bound within prime particles, which size is between 10 and 63 nm, that in turn form bigger agglomerates 200 nm in size, which further cluster building up agglomerates 5–20 μm in size.     

聚乙烯醇模板中原位水热法羟基磷灰石纳米颗粒的控制制备及表征

具有生物活性和生物相容性的羟基磷灰石/高分子复合材料的合成和可控制备,是当今生物材料领域研究的重要热点,在生物可降解聚乙烯醇高分子模板中,采用原位水热法,系统研究了具有生物活性的纳米HAP的可控制备,并对水热时间和模板剂浓度对羟基磷灰石/聚乙烯醇复合材料中HAP微粒形貌、大小的影响进行系统研究.结果表明,水熟时间从0h增加到16h,PVA/HAP微粒中HAP形貌逐渐由不规整的球状、短棒状变为规整的长棒状,水热时间从16h增加到72h,长棒状的PVA/HAP微粒的形貌变化不大;模板高分子(聚乙烯醇)浓度越大,获得的HAP微粒越小.     

Size-controlled synthesis of hydroxyapatite nanorods in the presence of organic modifiers

Size-controlled synthesis of hydroxyapatite nanorods was carried out by chemical precipitation followed by hydrothermal treatment using trisodium citrate, Tween 20, and polyethylene glycol (MW 600) as organic modifiers and starting from calcium nitrate and phosphoric acid. The particle sizes of the resultant hydroxyapatite nanorods varied with the chemical structures of the present organic modifiers and the crystallinity of the hydroxyapatite increased with an increasing autoclaving temperature.     

Convenient conversion of calcium carbonate to hydroxyapatite at ambient pressure

The synthesis of hydroxyapatite is described starting from calcium carbonate and monoammoniumphosphate in stoichiometric amounts. The novel aspect concerns the reaction conditions which are simple mixing in water at ambient pressure and 60 °C. The calcium carbonate solid phase slowly evolves CO₂ gas and buffers the solution at a pH value of 8.05 where hydroxyapatite precipitates. The main advantages of this reaction pathway are the absence of nitrate salts, the availability of the starting materials and the purity of the final product.     

Control of phase composition in hydroxyapatite/tetracalcium phosphate biphasic thin coatings for biomedical applications

Biphasic calcium phosphates comprising well-controlled mixtures of nonresorbable hydroxyapatite and other resorbable calcium phosphate phases often exhibit a combination of enhanced bioactivity and mechanical stability that is difficult to achieve in single-phase materials. This makes these biphasic bioceramics promising substrate materials for applications in bone tissue regeneration and repair. In this paper we report the synthesis of highly crystalline, biphasic coatings of hydroxyapatite/tetracalcium phosphate with control over the weight fraction of the constituent phases. The coatings were produced by pulsed laser deposition using ablation targets of pure crystalline hydroxyapatite. The fraction of tetracalcium phosphate phase in the coatings was controlled by varying the substrate temperature and the partial pressure of water vapor in the deposition chamber. A systematic study of phase composition in the hydroxyapatite/tetracalcium phosphate biphasic coatings was performed with X-ray diffraction. Tetracalcium phosphate in the coatings obtained at high substrate temperature is not formed by partial conversion of previously deposited hydroxyapatite. Instead, it is produced by nucleation and growth of tetracalcium phosphate itself from the ablation products of the hydroxyapatite target or by accretion of tetracalcium phosphate grains formed during ablation. This finding was confirmed by formation of calcium oxide, not tetracalcium phosphate, after annealing of pure hydroxyapatite coatings at high temperatures of 700–850∘C.     

The influence of silicon substitution on the properties of spherical- and whisker-like biphasic <Emphasis Type="Italic">α</Emphasis>-calcium-phosphate/hydroxyapatite particles

In this work, the influence of the morphology of hydroxyapatite particles on silicon substitution through hydrothermal synthesis performed under the same conditions was investigated. Spherical- and whisker-like hydroxyapatite particles were obtained starting from calcium-nitrate, sodium dihydrogen phosphate, disodium-ethylenediaminetetraacetic acid and urea (used only for the synthesis of whisker-like particles) dissolved in aqueous solutions. Silicon was introduced into the solution using tetraethylorthosilicate. X-ray diffraction, infrared spectroscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy and transmission electron microscopy indicate that silicon doping induce different phase compositions and bioactivity of spherical- and whisker-like hydroxyapatite particles obtained under the same hydrothermal conditions. Silicon-substituted, spherical hydroxyapatites particles showed greater phase transformation to silicon-substituted α- calcium-phosphate compared with whiskers-like hydroxyapatite particles synthesized with the same amount of added silicon. Metabolic activity assay performed with SaOs2 osteosarcoma cells showed better biocompatibility of annealed biphasic spherical-like particles compared with annealed whiskerlike particles while dried spherical-like particles induce high cytotoxicity effect.     

Low temperature,pH-triggered synthesis of collagen–chitosan–hydroxyapatite nanocomposites as potential bone grafting substitutes

A pH-triggered synthesis strategy at low temperature was developed to initiate collagen self-assembly, chitosan precipitation and hydroxyapatite synthesis by ammonia diffusion into the acidic homogeneous stock solution for preparing bone-like nanocomposites. FTIR and XRD analyses were used to confirm the molecular interactions and the formation of bone-like hydroxyapatite in collagen–chitosan–hydroxyapatite nanocomposites. A facile modulation of hydroxyapatite content in the obtained nanocomposites was further validated by thermogravimetric analysis. SEM observations revealed that the unique microstructure of obtained nanocomposites was composed of collagen fibrils and nano needle-like objects dependent upon the relative ratio of inorganic to organic components. This strategy is convenient and also feasible to prepare collagen based bone-like nanocomposites.     

Size-controlled synthesis of hydroxyapatite nanorods by chemical precipitation in the presence of organic modifiers

Size-controlled synthesis of hydroxyapatite nanorods was carried out by chemical precipitation method using citric acid, sodium dodecyl sulphate, and sodium dodecylbenzene sulphonate as organic modifiers and starting from calcium nitrate, phosphoric acid, and ammonia solution. The crystallinity of the resultant hydroxyapatite increased with increasing the autoclaving temperature. The particle sizes of the resultant HAP nanorods varied with the presence of the different structured organic modifiers and the synthetic temperature. The interaction between the anions of the modifiers and the hydroxyapatite crystallites controlled the crystal growth.