亚微米羟基磷灰石/聚乳酸复合材料的制备及形貌分析

背景:聚乳酸同纳米羟基磷灰石制备骨组织工程支架材料有良好的生物相容性,但是纳米级羟基磷灰石易团聚、很难均匀分散在材料中,使无机粒子和有机高聚物之间的结合状况受影响。目的:制备亚微米羟基磷灰石/聚乳酸复合材料,探讨聚乳酸溶液浓度、羟基磷灰石在溶液中的分散时间及羟基磷灰石含量对其在聚乳酸基体中分散性的影响,并分析复合材料的表面形貌、断面、复合材料界面状况。方法:采用溶液共混的方法,借助超声波分散技术,将亚微米羟基磷灰石以不同比例分散于溶剂为氯仿的聚乳酸溶液中,而后在室温下除去混合体系中的氯仿制得不同含量的亚微米羟基磷灰石/聚乳酸复合材料。观察不同溶液浓度对亚微米羟基磷灰石在溶液中的分散性的影响。借助扫描电镜、红外光谱分析亚微米羟基磷灰石/聚乳酸复合材料的断面、界面状况。结果与结论:在亚微米羟基磷灰石/聚乳酸复合材料质量比为0.15:1,分散时间大于30min,聚乳酸溶液浓度为0.14kg/L时,可使得羟基磷灰石在该浓度下有着较好分散性;而当亚微米羟基磷灰石含量超过15%就会在复合材料中产生团聚;红外分析表明,溶液共混制备的复合材料中亚微米羟基磷灰石/聚乳酸复合材料其特征官能团的位置没有发生变化。表明:借助超声波振荡的方法,可实现亚微米亚微米羟基磷灰石与聚乳酸复合材料较好的溶液共混,有望提高复合材料的界面状况。     

胶原羟基磷灰石（C／HA）组织埋藏

我们采用自制的Ｉ型胶原和羟基磷灰石做家兔皮下组织埋藏，分别在一个月和一个半月取出，组织切片证明应用胶原组比对照组的羟基磷灰石间的纤维结缔组织多，成纤维细胞浸润多，微血管丰富。炎症反应消失，无脱粒现象，结果证明胶原和羟基磷灰石联合植入组织比单用羟基磷灰石好。     

羟基磷灰石/胶原-聚乳酸三维多孔框架材料的制备成形及分析

目的：合成新型的复合生物材料框架作为骨组织工程研究的细胞外基质材料。方法：本研究采用材料学自组装技术的原理，以Ⅰ型胶原蛋白为分子模板，引导钙磷盐在液相中的矿化，制备具有天然骨基质层状结构的羟基磷灰石／胶原复合材料，并以热致分相法制备了羟基磷灰石／胶原-聚乳酸复合三维多孔框架。结果：羟基磷灰石／胶原复合材料具有与天然骨基质相似的成分与结构，加入聚乳酸制备成三维多孔框架，孔隙直径界于50um-300um。结论：羟基磷灰石／胶原-聚乳酸复合三维多孔框架可能作为骨组织工程良好的细胞外基质材料。     

纳米羟基磷灰石/Ⅰ型胶原/壳聚糖复合支架材料的制备与优化

目的制备适合于骨组织工程的高强度纳米羟基磷灰石/Ⅰ型胶原/壳聚糖复合支架材料。方法用原位合成法代替传统的直接分散法,以胶原和壳聚糖为模板原位合成羟基磷灰石,再用冷冻干燥法使材料成型,制成可用于骨组织工程的多孔支架材料。结果制备的材料孔隙率高,孔的连通性好,材料中羟基磷灰石结晶度更小,表面能大,与有机物基底结合紧密,也能为成骨细胞的粘附提供更多的活性位点。结论用紫外辐照对材料进行处理,能使其抗压性能得到提高。制备的支架材料适用于骨组织工程。     

纳米羟基磷灰石骨修复复合材料的研究进展

羟基磷灰石（Hydroxyapatite，HA）是一种性能良好的骨修复材料，但是由于脆性而限制了它在承力部位的应用。天然骨本身是纳米羟基磷灰石（Nanohydroxyapatite，n．HA）和胶原的复合材料，从仿生的角度看，n—HA与其它材料复合可以提高生物相容性和力学性能。目前研究的纳米羟基磷灰石复合材料可分为两类：非降解的纳米羟基磷灰石复合材料和可降解的纳米羟基磷灰石复合材料。前者包括n—HA/聚乙烯、n-HA／尼龙以及n—HA／聚丙烯酸。后者主要有n—HA与胶原、明胶、壳聚糖、聚乳酸和聚酸酐等的复合材料。本文详细综述了近年来纳米羟基磷灰石复合材料的制备、力学性能以及生物学性能的研究进展。     

多层软骨组织工程支架的制备

软骨组织工程为关节软骨损伤的治疗提供了一种理想的治疗途径,但体外构建的软骨如何在临床应用时采用适当的方法短期内在体内进行良好地固定仍然没有得到很好的解决,阻碍了采用组织工程方法治疗关节软骨疾病的临床应用.本研究通过冷冻干燥的方法制备出一个上层为胶原,下层逐层过渡到以羟基磷灰石为主的复合一体化软骨组织工程支架,利用复合支架下层羟基磷灰石良好的骨传导作用,将支架整体通过底部的快速固定达到对上层软骨进行固定的目的.本研究对该复合支架的制备及其形态结构特点进行了初步研究.结果表明胶原层的孔径孔隙率可以通过冷冻温度及胶原溶液浓度进行控制;羟基磷灰石粒度及其粒度分布明显影响其在胶原支架内部的分布;SEM照片表明用该方法制备出了三层具有不同羟基磷灰石含量的复合胶原羟基磷灰石软骨组织工程支架,支架总高度为6cm,每层高度约为2cm,三层之间不存在界面形成了一个均匀的整体结构.为软骨组织工程提供了一种新型的支架.     

纳米羟基磷灰石对人脐带静脉血管内皮细胞的毒性评价

背景：有研究应用脉冲激光沉积合成技术在人工心脏机械瓣膜上沉积胶原制备了新型纳米羟基磷灰石薄膜涂层。 目的：观察此种新型纳米羟基磷灰石薄膜对人脐带静脉血管内皮细胞的毒性。 方法：分别采用纳米羟基磷灰石薄膜常温浸提液、纳米羟基磷灰石薄膜高温浸提液、高密度聚乙烯及苯酚溶液培养人脐静脉血管内皮细胞,72 h内倒置相差显微镜下观察细胞生长状况;培养7 d时采用CCK-8法检测细胞增殖与毒性分级。 结果与结论：培养24 h,纳米羟基磷灰石薄膜常温浸提液组、纳米羟基磷灰石薄膜高温浸提液组和高密度聚乙烯组细胞生长良好,呈梭形,折光性强,3组细胞形态、数量无明显差异;苯酚溶液组细胞多为悬浮、圆形、固缩的死细胞;48 h时,除了苯酚溶液组外,其余3组细胞数量明显增加,细胞生长密集,至72 h时细胞生长旺盛,间隙显著减小。培养7 d内,纳米羟基磷灰石薄膜常温浸提液组、纳米羟基磷灰石薄膜高温浸提液组和高密度聚乙烯组细胞增殖活性无差异,均高于苯酚溶液组(P < 0.05),纳米羟基磷灰石薄膜毒性级别为0至1级,表明纳米羟基磷灰石人工心脏机械瓣膜有良好的组织细胞相容性,无毒性作用。中国组织工程研究杂志出版内容重点：生物材料;骨生物材料; 口腔生物材料; 纳米材料; 缓释材料; 材料相容性;组织工程全文链接：     

纳米羟基磷灰石悬浮液稳定性能的研究

为了得到稳定分散的纳米羟基磷灰石水悬浮液,以羧甲基纤维素钠（CMCNa）作分散剂,采用吸光率实验考察了羧甲基纤维素钠的用量及超声分散时间对纳米羟基磷灰石水悬浮液稳定性的影响,并对其分散机理进行了初步的探讨。结果表明：CMCNa作分散剂时,能有效地分散纳米羟基磷灰石粒子,得到均匀、稳定的纳米羟基磷灰石水悬浮液体系;当CMCNa用量为0.35wt%、超声时间为150s时分散效果最佳;CMCNa分散后,体系的Zeta电位的绝对值提高了69.82mV;CMCNa对纳米HAP悬浮液的稳定分散作用主要是通过粒子间的静电作用和空间位阻来实现的。由此可见,CMCNa对HAP纳米粒子具有较好的分散效果,是制备高分散稳定HAP的理想分散剂。     

纳米相羟基磷灰石/胶原复合材料研究进展

综述羟基磷灰石(hydroxyapatite,HA)/胶原复合材料的研究进展,着重阐述自组装纳米相羟基磷灰石/胶原复合材料的制作方法、结构特点、体内植入后修复骨缺损的效果及降解过程。基于仿生学设计的纳米相羟基磷灰石/胶原复合材料,其HA纳米晶体约50～100nm,HA的C-轴沿胶原纤维排列,形成片状包绕胶原纤维束,HA和胶原分子之间为牢固的化学键性结合,为自组装的纳米结构,和自然骨中钙化的胶原相同。复合材料体内植入后降解和骨替代的过程与骨的改建过程相似。纳米相羟基磷灰石/胶原复合材料具有生物降解性高、表面能大、生物活性好、生物相容性好等特点,作为骨修复和重建材料具有更好的前景。     

纳米相羟基磷灰石/胶原复合材料研究进展

综述羟基磷灰石（hydroxyapatite,HA）/胶原复合材料的研究进展,着重阐述自组装纳米相羟基磷灰石/胶原复合材料的制作方法、结构特点、体内植入后修复骨缺损的效果及降解过程.基于仿生学设计的纳米相羟基磷灰石/胶原复合材料,其HA纳米晶体约50～100nm,HA的C-轴沿胶原纤维排列,形成片状包绕胶原纤维束,HA和胶原分子之间为牢固的化学键性结合,为自组装的纳米结构,和自然骨中钙化的胶原相同.复合材料体内植入后降解和骨替代的过程与骨的改建过程相似.纳米相羟基磷灰石/胶原复合材料具有生物降解性高、表面能大、生物活性好、生物相容性好等特点,作为骨修复和重建材料具有更好的前景.     

Microspheres of hydroxyapatite/reconstituted collagen as supports for osteoblast cell growth.

Microspheres comprised of particulate hydroxyapatites dispersed in fibrous collagen matrices were prepared. The procedure involved the droplet formation of hydroxyapatite/collagen mixture emulsified in olive oil, followed by the reconstitution of collagen in the presence of hydroxyapatite particles at 37 degrees C. Various sizes of microspheres could be obtained by controlling the stirring speed of the emulsified mixture. By increasing the stirring speed from 200 to 350 and 500 rpm, the average diameter of the microspheres decreased from 1038 to 513 and 226 microm, respectively. The sizes of the microspheres reduced substantially to a range of 141 microm when 2%. Span 85 was present in the emulsion mixture stirring at 200 rpm. The microspheres thus obtained can be used as carriers to support the growth of osteoblast cells. Osteoblast cells derived from calvaria proliferated from 1.5 x 10(5) to 4.5 x 10(5) cells/ml in 7 days. Correspondingly, the alkaline phosphatase activity increased 6 fold during this period. These results suggested that the hydroxyapatite/collagen microspheres could be used as the filling materials for bone defect.     

The mechanical properties and solubility of strontium-substituted hydroxyapatite.

The mechanical properties and solubility of sintered Sr-substituted hydroxyapatites were examined in order to investigate the influences of Sr incorporation into hydroxyapatite in bones and teeth on them. Hydroxyapatite (HAp), Sr-substituted hydroxyapatite (Ca.SrAp), and strontium-hydroxyapatite (SrAp) were synthesized and sintered. The bending strength and Young's modulus were measured. Also, solubility in isotonic NaCl solution was examined. The Young's modulus of Sr-substituted hydroxyapatite (Sr wt% = 1.0) and hydroxyapatite surface treated with Sr ion were greater than that of hydroxyapatite. The bending strengths of Sr-substituted hydroxyapatites (Sr/Ca = 4/6 and less) were reduced slightly compared to that of hydroxyapatite. The bending strength of hydroxyapatite surface treated with Sr ion was increased compared to that of hydroxyapatite. The solubility in isotonic NaCl solution at 37 degrees C was increased with an increase in Sr content. The effects of Sr on the mechanical properties and solubility of bones and/or teeth are discussed.     

含氟羟基磷灰石的合成与性能研究

采用湿法合成羟基磷灰石和两种不同氟含量的含氟羟基磷灰石粉,在300,600,900度热处理,并将900度热处理的两种含氟羟基磷灰石及羟基磷灰石的压片在模拟体液内浸泡,采用扫描电镜及溶液离子浓度测定法观察其体外生物活性,红外光谱分析显示通过热处理可去除含氟痉基磷灰石及羟基磷灰石内的杂质成分,获得标准比的羟基磷灰石,X线衍射分析显示含氟羟基磷灰石的热稳定性差,900度出现很弱的β－Ca3(PO4)2衍射峰,在模拟体液中羟基磷灰石和氟含量低的磷灰石表面可沉淀出骨状磷灰石。     

Heterogeneous synthesis of fluoridated hydroxyapatites.

Fluoridated hydroxyapatites were synthesized with two different modes of fluoride supply: by supplying F(-)-free solution initially, followed by a F(-)-containing solution whose fluoride concentration was stoichiometrically equal to that of fluorapatite; and with the order of supply of these solutions reversed. Both of these heterogeneously synthesized fluoridated hydroxyapatites showed typical calcium phosphate X-ray diffraction patterns; and both had similar total fluoride contents (0.94 +/- 0.02 and 0.99 +/- 0.03 mmol/g, respectively), i.e. half of the maximum fluoride content of fluorapatite. However, they differed considerably in their physico-chemical properties. The former had a wider peak breadth of X-ray diffraction and a lower apparent solubility (Ca = 12.2 +/- 0.7 mmol/l) than the latter (Ca = 19.8 +/- 0.4 mmol/l) at 37 degrees C and pH 4.0. Wavelength dispersive spectroscopy attached to scanning electron microscopy gave clearly different spectra. Electron spectroscopy for chemical analysis of apatite pellets made by pressing and heating showed a slightly larger F1s signal at the crystal surface of the former, although the difference was not marked. These results suggest that two different types of heterogeneous fluoridated hydroxyapatites were formed, hydroxyapatite covered with fluorapatite and fluorapatite covered with hydroxyapatite.     

Novel synthesis and characterization of an AB-type carbonate-substituted hydroxyapatite.

A novel synthesis route has been developed to produce a high-purity mixed AB-type carbonate-substituted hydroxyapatite (CHA) with a carbonate content that is comparable to the type and level observed in bone mineral. This method involves the aqueous precipitation in the presence of carbonate ions in solution of a calcium phosphate apatite with a Ca/P molar ratio greater than the stoichiometric value of 1.67 for hydroxyapatite (HA). The resulting calcium-rich carbonate-apatite is sintered/heat-treated in a carbon dioxide atmosphere to produce a single-phase, crystalline carbonate-substituted hydroxyapatite. In contrast to previous methods for producing B- or AB-type carbonate-substituted hydroxyapatites, no sodium or ammonium ions, which would be present in the reaction mixture from the sodium or ammonium carbonates commonly used as a source of carbonate ions, were present in the final product. The chemical and phase compositions of the carbonate-substituted hydroxyapatite was characterized by X-ray fluorescence and X-ray diffraction, respectively, and the level and nature of the carbonate substitution were studied using C-H-N analysis and Fourier transform infrared spectroscopy, respectively. The carbonate substitution improves the densification of hydroxyapatite and reduces the sintering temperature required to achieve near-full density by approximately 200 degrees C compared to stoichiometric HA. Initial studies have shown that these carbonate-substituted hydroxyapatites have improved mechanical and biologic properties compared to stoichiometric hydroxyapatite.     

Biomechanical Design in Osteogenic Engineering

The bone is a naturally occurring composite system comprising collagen matrix and hydroxyapatites capable of generating sufficient strength and toughness to support mechanical loads and resist fracture,respectively.The material strength depends largely on the elastic properties,whereas the toughness depends on not only the elastic,but also the plastic properties.Thus,both elastic and plastic properties must be considered in the analysis of bone biomechanics and the design of osteogenic materials.The bone is capable of optimizing its elastic and plastic properties by integrating stiff hydroxyapatites and ductile collagen fibrils into a hierarchically ordered architecture,an effective mechanism to support the bone strength and toughness.Such a mechanism can be used as a model for designing osteogenic materials.     

Effect of collagen on the mechanical properties of hydroxyapatite coatings

In this study, the mechanical properties of bioactive coatings on Ti6Al4V substrates were investigated using instrumented nanoindentation. The aim was to observe the differences in the mechanical properties before and after immersion in collagen solution. The hydroxyapatite coatings were prepared through two processes: self-assembly in simulated body fluid and a hydrothermal method. Sintered hydroxyapatite disks were used as controls. The test samples were then incubated in a dilute collagen solution for 24 hours to produce composite coatings. The materials were investigated using XRD, SEM and nanoindentation. The results showed that the grain sizes of the hydroxyapatite coatings formed using two processes were 1?μm and 10?μm, respectively. The Young's modulus of the pure hydroxyapatite, the disk and the coatings, was 3.6 GPa. After collagen incubation treatment, the composites had a Young's modulus of 7.5 GPa. The results also showed that the strengthening phenomena of collagen were more obvious for homogeneous and small-grain hydroxyapatite coatings. These results suggest that there are similarities between these HAp/collagen composited and natural composite materials, such as teeth and bones.     

Studies on the microspheres comprised of reconstituted collagen and hydroxyapatite

Microspheres comprised of hydroxyapatite particles, dispersed in reconstituted fibrous collagen, were prepared and characterized. The hydroxyapatite particles distributed evenly throughout the collagen matrix of the microsphere. Diameters of the reconstituted collagen fibers ranged from 30 to 90 nm, and exhibited a regular banding pattern with cross-striation of 50-60 nm under transmission electron microscope, suggesting that the reconstitution of collagen was not hindered by the hydroxyapatite particulates. When osteoblast cells isolated from newborn rat calvaria were seeded and cultured on the microspheres, the cell density increased from 2x10(4) to 3.2x10(4)cells/cm(2) in 8 days. Von Kossa staining exhibited spotty accumulation of mineral deposits on microspheres indicating matrix mineralization of the cultured cells. Analyses by electron microscopy and confocal microscopy showed that the osteoblast cells spread and attached to the microsphere via focal adhesion, while F-actin and DNA staining demonstrated the presence of stress fibers; moreover, mitotic cells could be observed. Together, these results indicate that osteoblast cells are capable of proliferating, differentiating and mineralizing in the matrix of the microspheres, and suggest that the microspheric composite is a potential grafting material for future clinical applications.     

Synthesis of Si,Mg substituted hydroxyapatites and their sintering behaviors

Si, Mg-substituted hydroxyapatites, alone and co-substituted, have been prepared to obtain biomaterials having an improved biocompatibility. From FT-IR, XRD and ICP analyses, it was confirmed that single phases of hydroxyapatite substituted by Si alone or co-substituted by Si, Mg. The XRD data indicated the absence of extra phases related to silicon and magnesium oxide or other calcium phosphate species. Si-substituted hydroxyapatite of up to 2 wt% for Si and Si, Mg co-substituted hydroxyapatite of 1 wt% for the each ion keep their original structures intact for the sintering temperatures of up to 1200 degrees C. However, it is observed that ion substitutions by an amount higher than the above ratios for each hydroxyapatite lead to destabilization of original structures of the hydroxyapatite and to the production of tricalcium phosphate and calcium phosphate silicate phases when the samples were sintered at 1100 degrees C or higher.     

Osteogenic differentiation of cultured marrow stromal stem cells on surface of microporous hydroxyapatite based mica composite and macroporous synthetic hydroxyapatite.

In order to investigate the significance of hydroxyapatite based microporous composite (HA/mica composite) surfaces and a macroporous synthetic hydroxyapatite, rat marrow cell culture, which shows osteogenic differentiation, was carried out on six different culture substrata (two control culture dishes, two identical HA/mica composites, and two identical macroporous synthetic hydroxyapatites). A culture period of two weeks in the presence of beta-glycerophosphate (BGP), ascorbic acid, and dexamethasone resulted in abundant mineralized nodule formations that were positive for alkaline phosphatase (ALP) stain. The stain on the macroporous synthetic hydroxyapatite and the HA/mica composites were intense, the enzyme activity being about double that of control culture dishes. These data indicate that the synthetic macroporous hydroxyapatite surface and the HA/mica composite surface promotes osteoblastic differentiation.