电纺直写制备聚己内酯支架形貌及精度

作为一种新型的微纳制造技术,熔体直写电纺被广泛用于组织工程支架的可控制备,有序的纤维沉积是该领域应用的前提条件。对于支架成型精度的探究,本文使用生物可降解材料聚己内酯（PCL）,采用自行设计的熔体电纺三维可控成型设备进行实验,考察了纤维间距对二维并行纤维沉积形貌及成型精度的影响,以及纺丝电压和网格大小对三维网格结构形貌及精度影响。结果表明,随着并行纤维设定距离的增大,纤维的沉积误差减小,并最终趋于平稳。对于三维网格结构,随电压的增加,最大沉积层数量先增大后减小,当纺丝电压为6kV时达到最大沉积层数15层。成型精度误差先减小后增大,当纺丝电压为7kV时,精度最高误差小于5%。随设定网格边长的增大,沉积层数不断增大。成型精度逐渐提高,当网格边长大于等于1.5mm时,沉积误差趋于稳定,并维持在5%左右。     

电纺聚己内酯纤维直径工艺参数正交设计优化

本研究采用正交设计法研究静电纺丝法工艺过程对聚己内酯纤维直径的影响因素.主要研究纺丝液浓度、纺丝电压、注射泵进料速率三个因素对于纤维直径的影响.结果表明溶液浓度是影响纤维直径最主要的因素,次要影响因素是纺丝电压、进料速率.同时成功制备了纤维直径分别为0.35±0.09μm,0.95±0.09 μm,6.48±0.50 ...     

静电纺工艺参数对聚己内酯纳米纤维直径的影响

用静电纺丝法制备组织工程所需的纳米纤维及材料,在实验中主要研究了基本的工艺参数对所获纤维直径的影响。纤维或非织造膜由两种溶剂系统所制备:氯仿与N,N-二甲基甲酰胺(DMF)的混合剂及含少量(约40μg)嘧啶的乙酸溶液。为了研究聚合物浓度、DMF含量、施加电压、极距、溶剂系统等因素的影响,使用了扫描电子显微镜、溶液黏度仪、溶液电导率测试仪等。结果表明:随着聚合物浓度上升,纤维的直径先增加后减小;随着溶液中DMF含量的增加,纤维直径不断减小;电压对纤维直径无明显的影响;极距需适中,过大过小都会产生珠状纤维;含少量嘧啶(40μg的乙酸溶剂所获得的聚己内酯(PCL)纳米纤维比由氯仿和DMF的混合溶剂所获得的PCL纳米纤维更加细而均匀。     

碳酸乙烯酯对聚己内酯/冰乙酸电纺纤维的影响

在聚己内酯(PCL)/冰乙酸(GAC)溶液体系中加入低毒低挥发性溶剂碳酸乙烯酯(EC),采用静电纺丝法成功制备纳米纤维,采用扫描电子显微镜研究了不同EC浓度对制得的纤维形貌和直径的影响。结果表明,当溶液中PCL质量分数为20%,EC体积分数从0%变化到9%时,纳米纤维数量增加,平均直径逐渐变小;当EC体积分数从9%变化到15%时,微米纤维或珠串状纤维数量开始增加,平均直径逐渐变大。对比研究了EC体积分数为9%的溶液与未加EC的溶液的纺丝稳定性,同时对比研究了由这两种溶剂分别制备的纳米纤维膜和微米纤维膜的结构和性能。结果表明,PCL/GAC/EC溶液体系黏度可在24h内保持稳定,满足连续电纺要求;X射线衍射测试结果表明两种纤维膜结晶构型一致,只是结晶度和晶粒大小有所区别;傅里叶变换红外光谱分析结果表明EC对PCL的化学结构没有影响;与微米纤维膜相比,纳米纤维膜的比表面积提高了362.6%,平均孔直径有所减小,接触角有所增大;纳米纤维膜的拉伸断裂应力稍大但断裂应变明显小于微米纤维膜。     

聚己内酯的熔体流动性能和挤出胀大

应用熔体流动速率仪,在温度为90～140℃和载荷为2.16～12.50 kg的条件下,考察了温度、表观剪切速率(γα)及管壁剪切应力((Τ)R)对聚己内酯(PCL)熔体流动性能和挤出胀大比(B)的影响.结果表明:在实验条件下,PCL熔体的剪切流动基本服从幂律定律.表观剪切黏度ηa与绝对温度的关系符合Arrhenius方程,ηa随着γa或ΤR的增加而非线性减小.B随着温度的升高而非线性降低,随着γa或(Τ)R的增加而非线性增大,达到最大值后B则下降.     

相分离制备聚己内酯纳米纤维支架的工艺探讨

以二氧六环/水为溶剂体系采用相分离方法首次成功制备了高孔隙率、具有纳米纤维状结构的聚己内酯（PCL）支架,并且支架是以球体为结构单元的基体。文中主要探讨了陈化温度和溶剂比例对于球状纳米纤维结构支架形成的影响,太低（-40 ℃）或太高的陈化温度（≥8 ℃）均不利于PCL纳米纤维结构的出现,只有适宜的实验温度才可以得到纳米纤维球状基体。同样,非溶剂比例越大越不利于纳米纤维球状基体的形成。     

静电纺丝制备聚己内酯载药纤维工艺参数研究

选用聚己内酯作为载体材料、5-氟尿嘧啶作为承载药物,研究了静电纺丝过程中纺丝液浓度、纺丝电压及收集距离对纤维直径的影响,对制备的聚己内酯载药纤维膜进行元素检测分析及力学性能测试,通过体外药物释放实验,验证了聚己内酯载药纤维膜药物控释的效果.结果表明,随着纺丝液的浓度和收集距离增加,纤维的平均直径增大;随着纺丝电压增加,...     

静电纺丝法制备聚己内酯纳米纤维的工艺研究

以可生物降解的两亲性聚合物-聚己内酯(PCL)为原料,三氯甲烷和N,N-二甲基酰胺(DMF)为混合溶剂,采用静电纺丝技术制备了不同尺寸的PCL纳米纤维,研究了不同的PCL溶液浓度和针头尺寸相关工艺参数对纳米纤维微观形貌结构和尺寸分布的影响,同时对有序PCL纳米纤维的制备工艺进行了初步研究。     

丝素-聚己内酯纳米纤维膜的制备工艺

以六氟异丙醇(HFIP)为溶剂,采用静电纺丝技术制备丝素(SF)-聚己内酯(PCL)复合纳米纤维膜。采用热场发射扫描电镜、Image-Pro Plus图像分析和力学拉伸的方法表征了纳米纤维膜的结构与力学性能。通过设计的三因素四水平正交试验对复合纳米纤维膜的多个指标进行了分析,采取归一化数据处理及平均权重分配的方式量化了复合纳米纤维膜的品质,确定了共混复合纳米纤维膜制备的最优工艺参数,并且采用最佳工艺参数制备了SF-PCL复合纳米纤维膜,分析了其力学性能。结果表明:在溶质质量分数为6%、溶质SF与PCL质量比为3∶2、纺丝流速1.2 mL/h时,SF-PCL复合纳米纤维膜具有较好的品质;双轴拉伸时的破坏机制与单轴不同,其断裂应力和应变只是单轴时的一半左右,膜的力学性能表现为各向同性。     

聚己内酯电纺直写支架纤维黏结性能研究

作为一种新型的微纳制造技术,电纺直写对于生物组织工程而言意义重大,而纤维间的黏结力直接影响最终组织支架的稳定性。本研究采用生物可降解材料聚己内酯(PCL),通过自行设计的熔体电纺三维可控成型设备进行直写电纺,探究了喷头温度、冷热纤维的搭接间隔时间以及环境温度对纤维黏结效果的影响,并用热重分析仪(TGA)进行表征。研究表明:随着喷头温度的升高,纤维间的黏结力先逐渐增大,在出现轻微波动后又呈减小趋势,其中在190~210℃区间内黏结效果最佳;随冷热纤维搭接时间间隔的延长,纤维间的黏结效果不断下降;此外,环境温度对纤维黏结效果的影响较大。     

配位型催化剂催化ε-己内酯开环聚合

聚己内酯由于良好的生物可降解性、生物相容性以及药物透过性在生物医学领域得到广泛研究。ε-己内酯开环聚合是合成聚己内酯的有效途径。综述了近年来配位型催化剂催化ε-己内酯开环聚合现状。     

Fiber Bridging during Melt Electrowriting of Poly(ε-Caprolactone) and the Influence of Fiber Diameter and Wall Height

Melt electrowriting (MEW) is a direct-writing technology for small diameter fibers; however, due to electrostatic attraction, the technique is restricted in how close these microfibers can be positioned on the collector. Here, the minimum interfiber distance between parallel poly(ε-caprolactone) MEW microfibers is determined for different fiber diameters and number of layers on noncoated and star-shaped poly(ethylene oxide-stat-propylene oxide) (sP(EO-stat-PO))-coated glass coverslips. The effect of the fiber diameter, the number of fiber layers, and shape of turning loops affect precision and the minimum interfiber distance. Single fibers with diameter of 5, 10, and 15 µm have a minimum interfiber distance without fiber bridging of 33 ± 2.7, 54 ± 2.2, and 62 ± 2.7 µm, respectively. Increasing the number of layers to ten increases this minimum interfiber distance approximately twofold to 60 ± 3.5, 97 ± 4.5, and 102 ± 2.7 µm for the increasing fiber diameters. The sP(EO-stat-PO) slightly increases the minimum interfiber distance for the 15 µm diameter group only, with spacing for the 5 and 10 µm fibers unaffected by the coating. Identifying and determining the fabrication limits for MEW is highly instructional for users working and designing scaffolds with this technology.     

化学物理联合微孔发泡成型制备聚己内酯多孔材料

将超临界气体发泡技术与化学发泡技术联合用于制备多孔材料。采用碳酸氢钠作为化学发泡剂,将聚己内酯与碳酸氢钠挤出共混之后,使用传统注射成型和微注射成型,进行了发泡实验对比。结果表明,物理化学联合发泡用于制备多孔材料具有可行性,化学发泡剂的加入不仅改善了整体发泡效果,还能够作为气泡成核剂促进物理发泡的质量。对于所得结构在一定程度上表现的泡孔相互连通性进行了讨论,同时对泡孔壁面上出现的“网”状结构进行了分析。气泡在成核生长过程中,对于泡孔壁产生多方向拉伸的作用,相邻气泡共同作用于公共壁面,最终导致壁面部分形成“网”状结构。     

Melt electrospinning writing of three‐dimensional star poly(ϵ‐caprolactone) scaffolds

In the last decade, the melt‐electrospinning technique has gained attention for the production of highly porous microfibrous tissue engineering scaffolds. The possibility of processing polymers without the use of organic solvents is one of the main advantages over solution electrospinning. In this study, computer‐controlled melt‐electrospinning of a commercial poly(?‐caprolactone) and of two batches with different molecular weights of a three‐arm star poly(?‐caprolactone) by means of a screw‐extruder‐based additive manufacturing system is reported. Experimental parameters such as processing temperature, extrusion flow rate and applied voltage were studied and optimized in order to obtain non‐woven meshes with uniform fibre morphology. Applying the optimized parameters, three‐dimensional scaffolds were produced using a layer‐by‐layer approach (0 ? 90° lay‐down pattern). © 2013 Society of Chemical Industry     

Melt electrospinning onto cylinders: effects of rotational velocity and collector diameter on morphology of tubular structures

Melt electrospinning writing is a direct‐writing additive manufacturing process that involves depositing a continuous, viscous and electrohydrodynamically stabilised molten jet onto a collector. Here, molten threads of medical‐grade polycaprolactone (PCL) are directed towards stationary/rotating cylindrical collectors (0–6600 rpm), including very slow revolutions well below the critical translation speed (approximately 600 mm min^?1) of the molten jet. In this slow‐rotation region, the speed of the jet is faster than the movement of the collector and buckled/coiled fibres are produced due to compressive viscoelastic forces. The results are porous PCL tubes with wall morphologies often associated with viscoelastic liquids impinging onto a surface. The curvature of the collector affects how the fibre is deposited, with preferential fibre deposition along the axis of the cylinder. When the collector rotation speed is increased to greater than the speed of the jet, then straight fibres are produced. Such tubular structures have applications in tissue engineering. © 2015 Society of Chemical Industry     

熔体静电纺丝直写技术在组织工程中的应用进展

熔体静电纺丝直写技术以其纤维直径、沉积形貌可控性高及无溶剂残留等优势,为高强度复杂形貌可控仿生组织工程（TE）支架的制备提供了巨大的空间,成为近年来的研究热点。本文首先简述了熔体静电纺丝直写技术相对于各类其他TE支架制备方法的优势;其次从工艺调控方面综述了熔体静电纺丝直写技术的工艺研究进展,并总结了实现复杂可控形貌TE支架的调控方法;随后从支架材料、形貌表征和细胞培养效果等方面综述了熔体静电纺丝直写技术的TE应用进展,并概括了该技术制备的TE拓扑结构支架的种类及特点;最后指出熔体静电纺丝直写技术具有广阔的研究前景,且该技术应以制备仿生、材料多样化以及复合支架为研究重点。     

Recent Advances in Synthetic Bioelastomers

This article reviews the degradability of chemically synthesized bioelastomers, mainly designed for soft tissue repair. These bioelastomers involve biodegradable polyurethanes, polyphosphazenes, linear and crosslinked poly(ether/ester)s, poly(ε-caprolactone) copolymers, poly(1,3-trimethylene carbonate) and their copolymers, poly(polyol sebacate)s, poly(diol-citrates) and poly(ester amide)s. The in vitro and in vivo degradation mechanisms and impact factors influencing degradation behaviors are discussed. In addition, the molecular designs, synthesis methods, structure properties, mechanical properties, biocompatibility and potential applications of these bioelastomers were also presented.     

静电纺丝制备有序纳米纤维的研究进展

2000年以来,静电纺丝技术成为高分子材料和纳米技术研究领域的一个新的热点。综述了近年来采用静电纺丝法制备有序纳米纤维的研究进展,并讨论了有序纳米纤维的潜在应用。     

Electrospun poly(D,L)‐lactide nonwoven mats for biomedical application: Surface area shrinkage and surface entrapment

Nanofibrous poly(D,L )‐lactide mats prepared by electrospinning are useful for numerous biomedical applications. However, it was observed that these mats tend to shrink under physiological conditions. In this research, a physical entrapment method to modify the polymer surface with poly(ethylene glycol) was developed to ensure dimensional stability and to increase the hydrophilicity of the surface of the mats. Nanofiber morphology was characterized by scanning electron microscopy. Surface element analysis was performed by high resolution X‐ray photoelectron spectroscopy. Water contact angles were determined to identify surface properties before and after surface entrapment. Canine fibroblasts were prepared and seeded onto the poly(D,L)‐lactide mats, followed by cell morphology study by SEM and cell viability tests by MTT assay, which confirmed the improvement of biocompatibility by surface modification. Taking the results into account, hydrophilic and area‐stable nanofibrous nonwoven mats were successfully produced, with potential applications as in vivo biomedical material. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Tetracycline hydrochloride-containing poly (ε-caprolactone)/poly lactic acid scaffold for bone tissue engineering application: in vitro and in vivo study

In the current study, tetracycline hydrochloride (TCH), an antibiotic against most of the medically relevant bacteria, was incorporated into poly (ε-caprolactone)/poly lactic acid solution in order to develop a composite scaffold with both antibacterial and osteoinductive properties for the repair of infected bone defects. The composite scaffolds were produced from poly (ε-caprolactone) (PCL) and poly lactic acid (PLA) solution (1:1 (w/w)) incorporated with 3, 5, and 10% (w/w) of TCH by thermally induced phase separation technique. The scaffolds were evaluated regarding their morphology, wettability, porosity, degradation, mechanical properties, and cellular response. The scaffold containing 10% of TCH (PCL/PLA/TCH10%) was chosen as the optimum scaffold for further investigation in a rat femoral defect model. The study showed that after eight weeks, the bone formation was relatively higher in PCL/PLA/TCH10%-treated group with completely filled defect when compared with control (PCL/PLA scaffold without TCH). Histopathological evaluation showed that the defect in PCL/PLA/TCH10%-treated group was fully replaced by new bone and connective tissue. Our results provide evidence supporting the possible applicability of TCH-containing scaffolds for successful bone regeneration.