均相自发泡法制备抗菌多孔复合骨修复支架

与植入骨修复材料相关的感染仍是临床面临的难题,能控释或缓释抗菌剂的骨修复材料在易感染骨缺损修复领域越来越受到青睐。在具有良好生物相容性和成骨作用的纳米羟基磷灰石/聚氨酯(nHA/PU)复合材料中添加磷酸银作为抗菌剂,复合磷酸氢钙结晶水合物(DCPD)作为发泡剂水的来源,通过释放DCPD中结晶水与PU中异氰酸根反应产生CO_2气体实现了复合材料均相发泡成型。实验结果显示,85℃条件下自发泡制备的载磷酸银羟基磷灰石/磷酸氢钙/聚氨酯(Ag_3PO_4-nHA/DCPD/PU)复合支架的孔隙率高达80%,抗压强度可达2.83 MPa;制备的抗菌支架能有效抑制细菌在材料表面黏附,与细菌接触24h后抑菌率可达95.45%。该方法简便易行,制备的孔隙分布均匀、贯通性好、孔隙率高和力学性能佳的抗菌复合支架在骨修复领域有较大的应用潜力。     

脂肪族聚氨酯/磷灰石复合材料的原位制备及性能

为避免芳香族聚氨酯在体内降解时产生有毒物质,选用生物相容性良好的脂肪族聚氨酯(PU)与生物活性的羟基磷灰石(HA)为原料,通过原位聚合法制备了脂肪族PU/HA组织工程用多孔支架,并采用SEM、IR和力学试验等方法对多孔支架的形貌和性能进行了表征,进一步研究了发泡剂(水)用量和HA含量对支架泡孔结构和力学强度的影响。结果表明,当发泡剂用量为1%～1.5%(质量分数)时制得的多孔PU/HA复合支架材料孔隙之间相互贯通,孔径范围分布在300～800μm,大孔壁上分布着孔径为50～200μm的小孔,孔隙率达80%以上。随HA含量增加,支架抗压强度和弹性模量显著上升。综合考虑HA的增强效果和组织工程支架的孔隙结构,本体系中HA的最佳添加量为40%(质量分数),发泡剂的最佳用量为1%(质量分数)。     

不同热处理温度下纳米羟基磷灰石/聚酰胺66多孔支架制备及力学性能研究

热处理温度是热致相分离法制备多孔支架材料的关键因素。在不同热处理温度下(60℃、75℃和90℃)制备了纳米羟基磷灰石/聚酰胺66(n-HA/PA66)复合多孔支架材料。对比研究了不同热处理温度下制备的多孔支架孔隙结构、孔隙率及力学性能。结果表明:处理温度对多孔支架的孔隙结构,孔隙率,力学性能有显著的影响,随着温度的升高,多孔支架的孔隙率、平均孔径升高,贯通性改善,但弹性模量和屈服极限降低。多孔支架的热处理温度为75℃时,其孔径、孔隙率和力学性能与天然松质骨相当,是较为理想的骨组织工程支架材料。     

超临界CO2中制备聚乳酸/羟基磷灰石复合支架材料

利用盐析/超临界CO2复合方法制备了一系列的PDLLA/HA三维多孔支架材料.利用这种方法可以避免使用有机溶剂、较高温度和降低常规气体发泡法所需的较长时间.制备的三维多孔支架的孔隙率最高达91%,孔与孔之间相互连通,孔分布均匀,孔径大小为100～300μm,抗压强度明显增加.详细研究了CO2压力、温度、浸润时间以及致孔剂含量等条件的变化对复合材料形貌和孔隙率的影响.     

多孔 n2 HA/ PA26复合材料的制备及性能

采用注塑方法制备了多孔纳米磷灰石/聚酰胺26 (n2 HA/ PA26) 复合材料 , 采用 SEM、XRD、IR、 力学性能测试考察了多孔材料的性能。结果发现 : 多孔纳米磷灰石/聚酰胺26复合材料的孔隙分布均匀 , 贯通性良好 , 孔的尺寸约为 100～700μm , 平均孔径约 300～500μm , 大孔壁上有丰富的微孔 ; 所得多孔复合材料的孔隙率可控 , 总孔隙率最高可达 881 6 %; 多孔材料的总孔隙率降低 , 则开孔率随之降低 ; 多孔纳米磷灰石/聚酰胺26 复合材料的抗压强度为 1. 1～15. 6 MPa , 压缩模量为 0. 4～1. 4 GPa ; 在总孔隙率相近的条件下 , 多孔材料的抗压强度随 n2 HA质量分数增加而升高; 发泡剂和发泡过程对组成纳米磷灰石/聚酰胺26复合材料的两组元材料的性质和结构无影响。这种多孔材料可望作为人体非承重部位的植入骨修复体和组织工程支架使用。     

制备条件对聚乳酸多孔支架微观结构的影响

采用粒子沥滤结合气体发泡的方法制备聚乳酸(PLA)多孔支架,探讨浓度、发泡剂、温度等条件对支架宏观形貌和微观性质的影响,研究各个因素之间的相互关系,研究其表面形貌与微观结构之间的关系。研究发现对于不同尺寸制孔剂制备的支架,通过调节浓度、温度等条件,可以得到相似的薄层多孔的表面形貌,其对应的微观结构和性能(力学、孔隙率、贯通性)较好。     

碳酸氢氨制孔制备聚乳酸(PLLA)/β磷酸三钙(β-TCP)复合骨修复多孔支架材料

采用混合溶剂(氯仿,丙酮)溶解后的聚乳酸(PLLA)与β磷酸三钙(β-TCP)、制孔剂碳酸氢氨(NH4HCO3)复合,冷冻干燥成型制备聚乳酸/β磷酸三钙多孔复合支架材料.正交实验结果表明,适当比例的混合溶剂在-10℃间体积收缩干燥制备的材料具有良好的成型性能和力学强度,碳酸氢氨(粒径200～400μm)质量比为30%(wt),PLLA/β-TCP质量比为1:1时,制备的支架材料抗压强度5.6MPa,孔隙率66.3%,孔径200～400μm.得到理想的复合骨修复多孔支架材料.     

软骨修复用 HA/PU多孔支架材料的制备与表征

研制了用于软骨的组织工程的HA／PU多孔支架材料，采用气体发泡法制备了三维贯通的多孔HA／PU支架材料，通过XRD、IR对其结构组成进行了分析，用DSC测量了玻璃化转变温度，用SEM观察了微观形貌和孔径尺寸，并计算了孔隙大小和孔隙率的分布．通过燃烧试验分析了HA／PU复合材料中HA的百分含量，并对力学性能进行了评估．结果表明，多孔HA／PU复合支架材料，其大小孔道相互贯通，孔径范围在100-800μm，大孔中含有微孔，孔隙率可达到78％-80％，HA含量达到30wt％，力学强度达到271kPa．多孔HA／PU复合材料具有一定的弹性，是一类性能很好的可望用于软骨修复的支架材料．     

湿法造纸-热塑成型法制备多孔干细胞培养支架初步研究

以涤纶纤维和复合热熔纤维(PE/PP)为原料,采用湿法造纸成型,热熔纤维增强的新方法制备三维多孔支架,制备过程不使用有机溶剂.使用扫描电子显微镜(SEM)、FT-IR光谱、拉伸实验对材料的结构和性能进行表征,结果表明,支架内部结点分布均匀,孔较大且连通性好,孔隙率达97%;制备过程不发生任何化学变化;弹性模量为(5.3...     

用于骨组织工程的羟基丁酸-戊酸共聚物/生物活性玻璃复合多孔支架材料

研究了用于骨组织工程的复合型羟基丁酸-戊酸共聚物／溶胶-凝胶生物活性玻璃多孔支架材料，采用溶液浇注沥滤法制备了任意形状的三维连通多孔结构支架，并进行三维结构表征和显微形貌观察；通过对成型条件的调节，可控制支架的孔径和孔隙率；在模拟生理体液中进行复合支架材料的生物活性测试。研究表明，通过控制致孔剂用量、尺寸大小和分散，得到的支架材料呈三维连通开孔结构，且孔隙分布均匀、孔隙率达90％以上；扫描电镜观察结果显示，羟基丁酸-戊酸共聚物与生物活性玻璃良好相容，后者粘附在支架孔壁上；支架在模拟生理体液中浸泡后发现生物活性玻璃表面有羟基碳酸磷灰石多晶体生成，表明复合支架仍保持了BG的生物活性。     

Morphological,mechanical, and biocompatibility characterization of macroporous alumina scaffolds coated with calcium phosphate/PVA

In bone tissue engineering, a highly porous artificial extracellular matrix or scaffold is required to accommodate cells and guide the tissue regeneration in three-dimension. Calcium phosphate (CaP) ceramics are widely used for bone substitution and repair due to their biocompatibility, bioactivity, and osteoconduction. However, compared to alumina ceramics, either in the dense or porous form, the mechanical strength achieved for calcium phosphates is generally lower. In the present work, the major goal was to develop a tri-dimensional macroporous alumina scaffold with a biocompatible PVA/calcium phosphate coating to be potentially used as bone tissue substitute. This approach aims to combine the high mechanical strength of the alumina scaffold with the biocompatibility of calcium phosphate based materials. Hence, the porous alumina scaffolds were produced by the polymer foam replication procedure. Then, these scaffolds were submitted to two different coating methods: the biomimetic and the immersion in a calcium phosphate/polyvinyl alcohol (CaP/PVA) slurry. The microstructure, morphology and crystallinity of the macroporous alumina scaffolds samples and coated with CaP/PVA were characterized by X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscopy (SEM/EDX) analysis. Also, specific surface area was assessed by BET nitrogen adsorption method and mechanical behavior was evaluated by axial compression tests. Finally, biocompatibility and cytotoxicity were evaluated by VERO cell spreading and attachment assays under SEM. The morphological analysis obtained from SEM photomicrograph results has indicated that 3D macroporous alumina scaffolds were successfully produced, with estimated porosity of over 65% in a highly interconnected network. In addition, the mechanical test results have indicated that porous alumina scaffolds with ultimate compressive strength of over 3.0 MPa were produced. Concerning to the calcium phosphate coatings, the results have showed that the biomimetic method was not efficient on producing a detectable layer onto the alumina scaffolds. On the other hand, a uniform and adherent inorganic–organic coating was effectively formed onto alumina macroporous scaffold by the immersion of the porous structure into the CaP/PVA suspension. Viable VERO cells were verified onto the surface of alumina porous scaffold samples coated with PVA–calcium phosphate. In conclusion, a new method was developed to produce alumina with tri-dimensional porous structure and uniformly covered with a biocompatible coating of calcium phosphate/PVA. Such system has high potential to be used in bone tissue engineering.     

醇化改性蓖麻油基聚氨酯/n-HA复合支架材料的结构及力学性能

有机/无机材料的两相界面作用和均匀复合是影响复合支架材料性能的主要因素。本研究通过工艺改进, 对聚氨酯软段成分进行改性得到醇化蓖麻油, 经原位聚合发泡制备出多孔复合支架, 较好地实现了纳米羟基磷灰石(n-HA)颗粒的均匀分散。结果表明, 改性聚氨酯基体有效增加了羟基值, 其与极性n-HA两相界面复合良好, 无明显界面分相和颗粒团聚发生。支架孔径分布均匀, 但支架材料的孔隙率、孔径大小和结晶度略有减小。红外光谱和X射线衍射分析表明, n-HA和醇化蓖麻油基聚氨酯基体的分子间存在丰富的氢键和化学键, 促进了无机-有机相的相容性和稳定性。醇化改性和纳米无机粒子添加对材料性能的协同作用有效改善了支架的力学性能, 复合支架的压缩强度和模量均大幅增长。该种n-HA/聚氨酯复合支架有望用于进一步的骨再生和骨组织工程研究。     

Sol–gel method to fabricate CaP scaffolds by robocasting for tissue engineering

Highly porous calcium phosphate (CaP) scaffolds for bone-tissue engineering were fabricated by combining a robocasting process with a sol–gel synthesis that mixed Calcium Nitrate Tetrahydrate and Triethyl Phosphite precursors in an aqueous medium. The resulting gels were used to print scaffolds by robocasting without the use of binder to increase the viscosity of the paste. X-ray diffraction analysis confirmed that the process yielded hydroxyapatite and β-tricalcium phosphate biphasic composite powders. Thus, the scaffold composition after crystallization of the amorphous structure could be easily modified by varying the initial Ca/P ratio during synthesis. The compressive strengths of the scaffolds are ~6 MPa, which is in the range of human cancellous bone (2–12 MPa). These highly porous scaffolds (~73 vol% porosity) are composed of macro-pores of ~260 μm in size; such porosity is expected to enable bone ingrowth into the scaffold for bone repair applications. The chemistry, porosity, and surface topography of such scaffolds can also be modified by the process parameters to favor bone formation. The studied sol–gel process can be used to coat these scaffolds by dip-coating, which induces a significant enhancement of mechanical properties. This can adjust scaffold properties such as composition and surface morphology, which consequently may improve their performances.     

Characterization of a novel bioactive composite using advanced X-ray computed tomography

A novel bioactive, porous silica–calcium phosphate nanocomposite (SCPC) that can be used to treat large bone defects in load-bearing positions has been tested and has shown great potential for applications in tissue engineering. Porosity is essential to the performance of the composite material as a tissue engineering scaffold, as porous scaffolds provide a physical, 3-D template to support new tissue formation. However, porosity characterization using conventional techniques such as porosimetry or scanning electron microscopy requires extensive preparation of samples and may destroy important features during preparation and analysis stage. In this work, the new composite is characterized using an advanced high resolution X-ray computed tomography, which is a non-destructive testing technique that allows construction of the 3-D topology of the microstructure. The results clearly show the effectiveness and versatility of this technique in characterizing the porous architecture of the novel composite biomaterial. The pore distribution, morphology and interconnectivity in the composite scaffolds were found to be ideal for use in tissue engineering applications.     

Polyurethane (PU) scaffolds prepared by solvent casting/particulate leaching (SCPL) combined with centrifugation

This article reports an enhanced solvent casting/particulate (salt) leaching (SCPL) method developed for preparing three-dimensional porous polyurethane (PU) scaffolds for cardiac tissue engineering. The solvent for the preparation of the PU scaffolds was a mixture of dimethylformamide (DFM) and tetrahydrofuran (THF). The enhanced method involved the combination of a conventional SCPL method and a step of centrifugation, with the centrifugation being employed to improve the pore uniformity and the pore interconnectivity of scaffolds. Highly porous three-dimensional scaffolds with a well interconnected porous structure could be achieved at the polymer solution concentration of up to 20% by air or vacuum drying to remove the solvent. When the salt particle sizes of 212–295, 295–425, or 425–531 µm and a 15% w/v polymer solution concentration were used, the porosity of the scaffolds was between 83–92% and the compression moduli of the scaffolds were between 13 kPa and 28 kPa. Type I collagen acidic solution was introduced into the pores of a PU scaffold to coat the collagen onto the pore walls throughout the whole PU scaffold. The human aortic endothelial cells (HAECs) cultured in the collagen-coated PU scaffold for 2 weeks were observed by scanning electron microscopy (SEM). It was shown that the enhanced SCPL method and the collagen coating resulted in a spatially uniform distribution of cells throughout the collagen-coated PU scaffold.     

骨组织工程用硅胶/掺锶β-磷酸三钙/硫酸钙复合多孔支架的制备与性能研究

以掺锶β-磷酸三钙/硫酸钙为原料,利用搅拌喷雾干燥法制备出掺锶β-磷酸三钙/硫酸钙复合小球,再将硅胶与制备的复合小球复合,通过在模具中堆垛聚集的方法,制备出硅胶/掺锶β-磷酸三钙/硫酸钙复合生物支架。采用XRD,SEM,FT-IR等方法分析制得复合多孔支架的成分、形貌以及结构特征,并研究复合生物支架的降解性、孔隙率、力学性能和细胞毒性等。结果表明:该复合多孔生物支架具有一定的不规则孔洞结构,小球与小球之间的孔隙约为0.2~1mm,而每个小球上也有大量的微孔,孔径在50~200μm之间,且平均孔隙率达到62%,基本能满足骨组织工程支架对孔隙率的要求;该复合多孔支架无细胞毒性,其降解周期约为80天,抗压强度约为0.1MPa,因此该支架在非承重骨组织修复方面具有良好的应用前景。     

机械活化增强多孔磷酸钙骨水泥支架的研究

本研究采用球磨对磷酸钙骨水泥(CPC)起始粉末进行机械活化处理, 以期改善CPC力学性能, 并探讨了其影响机理。采用激光粒度仪、比表面积测量仪和X射线衍射仪(XRD)表征球磨后的CPC粉末(Ball milling CPC, BCPC)。利用发泡法制备多孔BCPC支架, 采用万能力学试验机、XRD和扫描电子显微镜(SEM)表征多孔BCPC支架。结果显示, 球磨后的BCPC粉末平均粒径减小, 比表面积增大, 表观密度、堆积密度及紧密密度减小。BCPC支架孔隙率为(77.98 ± 0.58)%, 抗压强度为(4.11 ± 0.46) MPa, 相比CPC支架的(64.23 ± 2.32)%和(1.99 ± 0.43) MPa有显著提高。SEM结果显示BCPC支架具有数微米和数百微米的两种孔隙结构。XRD结果表明机械活化作用降低了DCPD、α-TCP、CaCO₃和HA的晶粒尺寸和结晶度, 促使DCPD向DCPA转化, 促进了各相磷酸钙盐的水化和HA的沉积, 提高了BCPC支架的力学性能, 为增强CaP基多孔材料的力学性能和扩展其临床应用提供了新途径。     

Effects of surfactants on the microstructure of porous ceramic scaffolds fabricated by foaming for bone tissue engineering

A porous scaffold comprising a β-tricalcium phosphate matrix and bioactive glass powders was fabricated by foaming method and the effects of surfactants as foaming agent on microstructure of scaffolds were investigated. Foaming capacity and foam stability of different surfactants in water firstly were carried out to evaluate their foam properties. The porous structure and pore size distribution of the scaffolds were systematically characterized by scanning electron microscopy (SEM) and an optical microscopy connected to an image analyzer. The results showed that the foam stability of surfactant has more remarkable influence on their microstructure such as pore shape, size and interconnectivity than the foaming ability of one. Porous scaffolds fabricated using nonionic surfactant Tween 80 with large foam stability exhibited higher open and total porosities, and fully interconnected porous structure with a pore size of 750-850 μm.     

磷酸钙相组成对类骨单位复合骨支架的影响

从组成上看, 自然骨是一种无机与有机的复合材料; 从结构上看, 致密骨的基本结构单位为内壁血管化的骨单位。本研究基于组成与结构仿生的原理制备组织工程化支架, 模拟具有复杂结构的密质骨的基本单位——骨单位。为此, 通过静电纺丝和双螺杆挤出相结合的两步制造法, 制备一种具有双层结构的聚己内酯/磷酸钙(PCL/CaP)复合骨支架, 其内层是由电纺纳米纤维组成的空心管, 可贴附内皮细胞层形成与哈佛氏管相类似的结构; 其外层是具有高孔隙率的螺旋状PCL/CaP微丝, 可复合前成骨细胞以模拟骨单位结构中的外层骨样组织。为进一步探索材料组成对于支架生物功能的影响, 分别设计了外层为PCL, PCL/双相磷酸钙(PCL/BCP)和PCL/β-磷酸三钙(PCL/β-TCP)的复合支架, 比较了材料组分变化对外层微丝结构及前成骨细胞(MC3T3-E1)活性的影响。相比于PCL和PCL/β-TCP, PCL/BCP微丝更能显著增强细胞的生长和钙的沉积, 并成功获得可精确调控不同细胞的空间分布的双层复合支架, 实现对复杂结构骨单位的模拟构建, 显示出很好的应用前景。     

In situ synthesis and characterization of porous polymer-ceramic composites as scaffolds for gene delivery

The use of three-dimensional scaffolds in gene delivery has emerged as a popular and necessary delivery vehicle for obtaining controlled gene delivery. In this report, techniques to synthesize composite scaffolds by combining natural polymers such as agarose and alginate with calcium phosphate (CaP) are described. The incorporation of CaP into the agarose or alginate hydrogels was performed in situ and the presence of CaP was confirmed by X-ray diffraction (XRD). The crystallite size of the CaP particles was determined to be 7.20 nm. Lyophilized, porous composites were examined under scanning electron microscopy (SEM) to estimate the size of the pores, an essential requirement for an ideal scaffold. The swelling properties of the composite samples were also investigated to study the effect of CaP incorporation on the behavior of the hydrogels. By incorporating CaP into the hydrogel, the aim is to synthesize a scaffold that is mechanically strong and chemically suitable for use as a gene delivery vehicle in tissue engineering.