PLGA组织工程支架材料在生理盐水中的降解性能

本文利用红外漫反射仪、DSC测试,并通过对PLGA组织工程支架在生理盐水中的失重率、分子量以及生理盐水pH值变化的研究,发现:孔径在200-300微米的PLGA组织工程支架,在37℃,振荡速度为160r/min的生理盐水中,随着降解时间的延长,分子量不断减小;随着降解时间的延长,支架重量有升有降,但长期呈下降的趋势;DSC测试显示,支架材料中的GA链相对于LA链更易降解;FTIR图谱显示,PLGA组织工程支架材料的降解主要是酯键水解。     

β-磷酸三钙/聚乳酸组织工程支架在模拟体液中的降解和矿化性能

利用扫描电镜、X射线衍射仪、红外漫反射仪,以及对β-磷酸三钙/聚乳酸组织工程支架在模拟体液(SBF)中失重率和模拟体液pH值的变化的测试,系统研究了聚乳酸组织工程支架在模拟体液中的降解和矿化性能。结果发现,随着β-磷酸三钙/聚乳酸组织工程支架在模拟体液中浸泡时间的增长,模拟体液的pH值有下降趋势;支架材料的质量是降解和矿化作用共同影响的结果。X射线衍射图谱和红外光谱(FT-IR)漫反射图谱研究表明,浸在SBF中的支架表面有磷灰石沉积物出现,且沉积物与β-磷酸三钙的晶型相似。     

β-磷酸三钙/聚乳酸组织工程支架在模拟体液中的降解和矿化性能EI北大核心CSCD

利用扫描电镜、X射线衍射仪、红外漫反射仪,以及对β-磷酸三钙/聚乳酸组织工程支架在模拟体液(SBF)中失重率和模拟体液pH值的变化的测试,系统研究了聚乳酸组织工程支架在模拟体液中的降解和矿化性能。结果发现,随着β-磷酸三钙/聚乳酸组织工程支架在模拟体液中浸泡时间的增长,模拟体液的pH值有下降趋势;支架材料的质量是降解和矿化作用共同影响的结果。X射线衍射图谱和红外光谱(FT-IR)漫反射图谱研究表明,浸在SBF中的支架表面有磷灰石沉积物出现,且沉积物与β-磷酸三钙的晶型相似。     

PLA-PEG-PLA/PLA组织工程支架在模拟体液中的降解和生物矿化性能

系统研究了含有聚乳酸-聚乙二醇-聚乳酸嵌段共聚物(PLA-PEG-PLA)的聚乳酸组织工程支架在模拟体液(SBF)中的降解和生物矿化性能。通过研究可以得到如下结论:随着含有PLA-PEG-PLA共聚物的聚乳酸组织工程支架在模拟体液中浸泡时间的增长,模拟体液的pH值有下降趋势;支架材料的质量有升有降,是降解和矿化作用共同影响的结果。X射线衍射图谱和FT-IR漫反射图谱研究表明,浸在SBF中的支架表面有磷灰石沉积物出现,并且PLA-PEG-PLA共聚物降解速度比PLA快。     

支架结构对聚乳酸组织工程支架在SBF溶液中降解进程的影响

本文通过对不同孔隙率和不同孔径的聚乳酸组织工程支架在模拟体液（SBF）中的降解性能的研究,探讨支架结构对聚乳酸组织工程支架在SBF溶液中降解进程的影响.研究发现：孔径适中的200-300微米致孔剂制得的聚乳酸组织工程支架材料在降解1周后比其它两种孔径（致孔剂粒径100微米以下、致孔剂粒径300-400微米）的支架材料的分子量更高,支架的降解性能更稳定;孔隙率越高支架材料的分子量降低得越慢.聚乳酸组织工程支架的失重率并不随着降解时间的增长而逐步增大,而是呈起伏状态,这是由于组织工程支架在SBF溶液中既有降解进程,又有沉积进程造成的.     

生物活性玻璃/聚乳酸组织工程支架在SBF溶液中的降解和矿化性能

利用扫描电镜、X衍射仪以及红外漫反射仪,并通过对生物活性玻璃/聚乳酸组织工程支架在模拟体液（SBF）中失重率及模拟体液pH值的变化的检测,系统研究了生物活性玻璃/聚乳酸组织工程支架在SBF中的降解和矿化性能。结果发现：随着含有生物活性玻璃的聚乳酸支架在SBF溶液中浸泡时间的增长,SBF的pH值不断下降;含有生物活性玻璃...     

溶胶凝胶法制备含有生物活性成分的PLGA组织工程支架材料

采用溶胶凝胶法制备了具有生物活性的SiO2/聚乙醇酸-乳酸共聚物（PLGA）组织工程支架材料。该方法选用廉价的硅溶胶作为硅源制备二氧化硅凝胶,简单易行,大大降低了成本。用模拟体液（SBF）溶液对含有SiO2的PLGA支架材料进行体外模拟浸泡实验。从电子探针照片上可以看到制得的含有SiO2的PLGA多孔支架材料有着良好的...     

生物活性玻璃/PLA-PEG-PLA/聚乳酸组织工程支架在SBF溶液中的降解和矿化

通过测定pH值、质量损失率、SEM、XRD和FTIR,系统研究了生物活性玻璃/聚乳酸-聚乙二醇-聚乳酸嵌段共聚物（PLA-PEG-PLA）/聚乳酸组织工程支架在模拟体液（SBF）中的降解和生物矿化性能。研究结果表明：随着支架在SBF溶液中浸泡时间的延长,SBF的pH值和支架的质量呈下降趋势;生物活性玻璃的存在使pH值升高,而PLA-PEG-PLA嵌段共聚物的存在使pH值降低。XRD、FTIR图谱和SEM图像表明：在SBF中浸泡一定时间后,有无定型或结晶不完善的磷灰石在生物活性玻璃/PLA-PEG-PLA/聚乳酸组织工程支架表面沉积形成,并且PLA-PEG-PLA共聚物降解速度比聚乳酸快;在SBF中浸泡7天后,PLA-PEG-PLA共聚物的含量已经很难通过FTIR检测出来。     

聚乳酸组织工程支架在SBF溶液中的降解和矿化性能

本文利用扫描电镜、X射线衍射仪以及红外漫反射仪,并通过对聚乳酸组织工程支架在模拟体液(SBF)中的失重率、分子量以及模拟体液pH值变化的测试,系统地研究了聚乳酸组织工程支架在模拟体液中的降解和矿化性能。结果发现:在模拟体液中,随着时间的增长,聚乳酸组织工程支架的分子量不断下降;但是其重量并不随着时间的增长而减小,而是有升有降。X-射线衍射图谱和FTIR漫反射图谱研究表明,在模拟体液中,聚乳酸组织工程支架的表面有磷灰石沉积物出现。     

ACF/PLGA骨组织工程复合支架的制备及其性能

本文利用溶剂灌制/粒子沥滤的方法将具有较强吸附性能的活性碳纤维(activated carbon fiber,ACF)掺杂于聚乳酸-羟基乙酸共聚物(poly(lactic-co-glycolic acid),PLGA)制备了一种新型ACF/PLGA骨组织工程复合支架。论文对比研究了纯PLGA支架以及两种ACF/PLGA支架(ACF含量为2.75%,8.26%)的结构和性能。SEM研究发现三者都具有较高的孔隙度,分别为73.5340%、75.1214%和79.8216%,且孔隙度随着ACF含量的增加逐渐增大;压汞法测得三者的孔径分布基本在50~250μm之间;研究其亲水性发现,其表面接触角随ACF含量增加逐渐减小,吸水率则逐渐增大。进一步研究发现在三种支架上种植小鼠成纤维细胞(L929),一天后细胞都较好粘附在支架上;ACF含量为8.26%的复合支架移植到小白鼠皮下组织,一月后HE切片显示支架周围组织的免疫排斥反应较小。掺杂ACF的PLGA复合支架除了具有良好的细胞粘附效果和组织相容性,相对于纯PLGA支架,还具有良好的孔径分布和亲水性,具有潜在的应用价值。     

In situ synthesized ceramic–polymer composites for bone tissue engineering: bioactivity and degradation studies

As an alternative to current bone grafting strategies, a poly-lactide-co-glycolide/calcium phosphate composite microsphere-based scaffold has been synthesized by the direct formation of calcium phosphate within forming microspheres. It was hypothesized that the synthesis of low crystalline calcium phosphate within forming microspheres would provide a site-specific delivery of calcium ions to enhance calcium phosphate reprecipitation onto the scaffold. Both polymeric and composite scaffolds were incubated in simulated body fluid (SBF) for 8 weeks, during which time polymer molecular weight, scaffold mass, calcium ion concentration of SBF, pH of SBF, and calcium phosphate reprecipitation was monitored. Results showed a 20% decrease in polymeric scaffold molecular weight compared to 11–14% decrease for composite scaffolds over 8 weeks. Composite scaffold mass and SBF pH decreased for the first 2 weeks but began increasing after 2 weeks and continued to do so up to 8 weeks, suggesting interplay between pH changes and calcium phosphate dissolution/reprecipitation. Free calcium ion concentration of SBF containing composite scaffolds increased 20–40% over control values within 4 h of incubation but then dropped as low as 40% below control values, suggesting an initial burst release of calcium ions followed by a reprecipitation onto the scaffold surface. Scanning electron micrographs confirm calcium phosphate reprecipitation on the scaffold surface after only 3 days of incubation. Results suggest the composite scaffold is capable of initiating calcium phosphate reprecipitation which may aid in bone/implant integration.     

Poly(lactide-co-glycolide)/hydroxyapatite nanofibrous scaffolds fabricated by electrospinning for bone tissue engineering

Poly(lactide-co-glycolide) (PLGA) nanofibrous composite scaffolds having nano-hydroxyapatite particles (HAp) in the fibers were prepared by electrospinning of PLGA and HAp with an average diameter of 266.6 ± 7.3 nm. Microscopy and spectroscopy characterizations confirmed integration of the crystalline HAp in the scaffolds. Agglomerates gradually appeared and increased on the fiber surface along with increase of the HAp concentration. In vitro mineralization in a 5 × simulated body fluid (SBF) revealed that the PLGA/HAp nanofibrous scaffolds had a stronger biomineralization ability than the control PLGA scaffolds. Biological performance of the nanofibrous scaffolds of the control PLGA and PLGA with 5 wt% HAp (PLGA/5HAp) was assessed by in vitro culture of neonatal mouse calvaria-derived MC3T3-E1 osteoblasts. Both types of the scaffolds could support cell proliferation and showed sharp increase of viability until 7 days, but the cells cultured on the PLGA/5HAp nanofibers showed a more spreading morphology. Despite the similar level of the cell viability and cell number at each time interval, the alkaline phosphatase secretion was significantly enhanced on the PLGA/5HAp scaffolds, indicating the higher bioactivity of the as-prepared nano-HAp and the success of the present method for preparing biomimetic scaffold for bone regeneration.     

Degradation behavior of hydrophilized PLGA scaffolds prepared by melt-molding particulate-leaching method: Comparison with control hydrophobic one

Porous PLGA/PVA scaffolds as hydrophilized PLGA scaffolds for tissue engineering applications were fabricated by a novel melt-molding particulate leaching method (non-solvent method). The prepared scaffolds exhibited highly porous and open-cellular pore structures with almost same surface and interior porosities (pore size, 200–300 μ m; porosity, about 90%). The in vitro degradation behavior of the PLGA and PLGA/PVA scaffolds was compared at 37^∘C in PBS (pH 7.4) with and without the solution change everyday to see the effect of solution pH as well as scaffold hydrophilicity on the degradation behavior. The changes in dimension, molecular weight, mechanical properties (maximum load and modulus), and morphology of the scaffolds were examined with degradation time. The degradation behavior of the PLGA and PLGA/PVA scaffolds was further investigated in vivousing a rat model (subcutaneously implantation). It was observed that both PLGA and PLGA/PVA scaffolds in decreasing pH condition (PBS no change) showed faster degradation than those in constant pH condition (PBS change everyday), owing to the enhanced intramolecular depolymerization by the increment of chain hydrophilicity caused by carboxylate groups as well as the autocatalysis of carboxylic acids accumulated in the solution by the cleavage of PLGA backbone ester bonds. The scaffolds in vivo condition also showed faster degradation than those in vitro, probably due to the aid of foreign body giant cells or enzymes. The PLGA/PVA scaffold showed slightly faster degradation than the PLGA scaffold for both in vitro and in vivo conditions. Author to whom all correspondence should be addressed.     

Dual-source dual-power electrospinning and characteristics of multifunctional scaffolds for bone tissue engineering

Electrospun tissue engineering scaffolds are attractive due to their distinctive advantages over other types of scaffolds. As both osteoinductivity and osteoconductivity play crucial roles in bone tissue engineering, scaffolds possessing both properties are desirable. In this investigation, novel bicomponent scaffolds were constructed via dual-source dual-power electrospinning (DSDPES). One scaffold component was emulsion electrospun poly(d,l-lactic acid) (PDLLA) nanofibers containing recombinant human bone morphogenetic protein (rhBMP-2), and the other scaffold component was electrospun calcium phosphate (Ca–P) particle/poly(lactic-co-glycolic acid) (PLGA) nanocomposite fibers. The mass ratio of rhBMP-2/PDLLA fibers to Ca–P/PLGA fibers in bicomponent scaffolds could be controlled in the DSDPES process by adjusting the number of syringes used to supply solutions for electrospinning. Through process optimization, both types of fibers could be evenly distributed in bicomponent scaffolds. The structure and properties of each type of fibers in the scaffolds were studied. The morphological and structural properties and wettability of scaffolds were assessed. The effects of emulsion composition for rhBMP-2/PDLLA fibers and mass ratio of fibrous components in bicomponent scaffolds on in vitro release of rhBMP-2 from scaffolds were investigated. In vitro degradation of scaffolds was also studied by monitoring their morphological changes, weight losses and decreases in average molecular weight of fiber matrix polymers.     

聚乳酸-羟基乙酸共聚物/磷酸钙骨水泥多孔复合支架的制备

利用定向冰晶-冷冻干燥法制备了具有定向孔隙结构的磷酸钙骨水泥支架材料, 将两种具有不同降解速率的聚乳酸-羟基乙酸共聚物(PLGA) 与磷酸钙骨水泥多孔支架进行多次浸润复合, 以改善支架的力学性能。结果表明: PLGA 与支架材料复合可大大提高复合支架材料的抗压强度, 经过PLGA 二次复合后, 复合支架抗压强度可达6. 37 MPa ±0. 54 MPa 。经过PLGA 复合的支架材料保持了复合前的孔隙结构, 在孔的轴向方向上具有定向排列的开口孔隙, 这些开口孔隙的存在有利于植入初期新生组织的长入。覆盖在骨水泥基体表面的PLGA 膜可以增强基体的强度并弥补基体表面的缺陷, 充填在孔隙内部的PLGA 泡沫体可以很好地承受外加载荷, 使复合支架材料具有较好的强度和韧性。      

Electrospinning of PLGA/gelatin randomly-oriented and aligned nanofibers as potential scaffold in tissue engineering

Electrospinning technique can be used to produce the three-dimensional nanofibrous scaffold similar to natural extracellular matrix, which satisfies particular requirements of tissue engineering scaffold. Randomly-oriented and aligned poly(lactic-co-glycolic acid) (PLGA) and PLGA/gelatin biocomposite scaffolds were successfully produced by electrospinning in the present study. The resulting nanofibrous scaffolds exhibited smooth surface and high porous structure. Blending PLGA with gelatin enhanced the hydrophilicity but decreased the average fiber diameter and the mechanical properties of the scaffolds under the same electrospinning condition. The cell culture results showed that the elongation of the osteoblast on the aligned nanofibrous scaffold was parallel to the fiber arrangement and the cell number was similar to that of randomly-oriented scaffold, indicating that the aligned nanofibrous scaffold provide a beneficial approach for the bone regeneration.     

Preparation of porous biodegradable poly(lactide-co-glycolide)/ hyaluronic acid blend scaffolds: Characterization, in vitro cells culture and degradation behaviors

A series of poly(lactide-co-glycolide) (PLGA)/ hyaluronic acid (HA) blend with different HA composition were used to fabricate scaffolds successfully. The pores of the three dimensional scaffold were prepared by particle leaching and freeze drying. The pore size was about 50–200 μ m and the porosity was about 85%. The characterizations of the scaffold, such as mechanical properties, hydrophilicity and surface morphologies were determined. Mouse 3T3 fibroblast was directly seeded on the scaffolds. The cell adhesion efficiency, cell morphology observed by scanning electron microscopy (SEM) and the degradation behavior of the blend scaffold were evaluated. In summary, the results show that the adhesion efficiency of cells on the PLGA/HA blend scaffold is higher than that on the PLGA scaffold. Moreover, the incorporation of HA in PLGA not only helps to increase the cell affinity but also tends to lead the water and nutrient into the scaffold easily.     

Fabrication of bioactive composite by developing PLLA onto the framework of sintered HA scaffold

Composite porous scaffolds of hydroxyapatite (HA)/poly-l-lactide (PLLA) were fabricated by a two-step immersing replication method. Structure and mechanical properties of both the single HA scaffold and the composite HA/PLLA scaffold were determined. The bioactivity of the scaffolds was evaluated by soaking in a simulated body fluid (SBF), and the formation of the apatite layer was determined by X-ray diffraction (XRD), Scanning Electron Microscope (SEM) and Energy-Dispersive Spectrometer (EDS). The results showed that without changing the highly interconnected porous structure, the HA/PLLA composite scaffold was mechanically enhanced to a great deal of extent compared with single HA scaffold. On the other hand, it is also suggested that the HA/PLLA scaffold was bioactive as it induced the formation of apatite on the surface of the composite scaffolds after soaking in SBF for 7 days.