氧化石墨烯增强的骨仿生静电纺左旋聚乳酸纳米纤维支架的制备及表征

利用静电纺丝技术制备了左旋聚乳酸/氧化石墨烯(PLLA/GO)复合纳米纤维毡。通过扫描电子显微镜(SEM)、透射电子显微镜(TEM)、孔隙率测试、傅里叶红外光谱分析(FTIR)以及拉伸测试分别对PLLA/GO纳米纤维的形貌结构、孔隙率及力学性能进行了研究。将小鼠骨髓间充质干细胞(MSCs)种植在TSF/PLLA纳米纤维上,通过荧光显微镜分析和碱性磷酸酶(ALP)测试、SEM观察细胞在材料表面的生长以及矿物沉积情况评价复合纳米纤维的生物学性能。结果表明,与纯的PLLA静电纺纳米纤维支架相比,PLLA/GO复合纳米纤维支架的纤维直径显著减小,孔隙率增大,力学性能明显得到改善,拉伸强度和杨氏模量均高于纯PLLA纳米纤维支架将近3倍,而且能够更好地促进MSCs的粘附、增殖和分化。     

静电纺丝制备壳聚糖/聚己内酯血管支架及表征

结合壳聚糖(CS)和聚己内酯(PCL)二者的优点, 以静电纺丝的方法制备了CS/PCL血管支架。采用SEM和电子万能试验机检测了该支架的结构和力学性能, 将内皮祖细胞(EPCs)与该支架膜复合培养, 评估了该血管支架维持细胞黏附、 繁殖和分化的能力。SEM结果显示: 通过静电纺丝可以得到多孔、 类似于天然细胞外基质的直径约400nm的纤维微结构; 当CS与PCL质量比为0.5时, 静电纺丝所制备的CS/PCL血管支架弹性最大形变达到31.64%, 应力-应变曲线显示其弹性变形能力较强; EPCs在CS/PCL血管支架黏附率可达95.1%, 荧光显微镜观察结果也显示了CS/PCL血管支架利于细胞黏附、 生长。      

石墨烯/聚酰胺6纤维的混合熔融纺丝工艺及性能EI北大核心CSCD

采用溶液混合冷冻干燥法制备了质量分数0.004%的石墨烯/聚酰胺6(PA6)粒料,再用2种工艺制备石墨烯/PA6纤维——石墨烯/PA6粒料直接熔融纺丝;石墨烯/PA6粒料加入双螺杆挤出机熔融混合、挤出、造粒、熔融纺丝。用万能试验机测试了纤维的拉伸性能;用差示扫描量热分析测试了纤维的熔融行为并计算了结晶度;用扫描电镜(SEM)观察了石墨烯/PA6纤维的微观形态。研究结果表明,微量石墨烯的加入能够显著改善PA6纤维的拉伸性能,制备的石墨烯/PA6纤维的拉伸强度和拉伸模量分别可达到270 MPa和9.4GPa;工艺一制备的石墨烯/PA6纤维的热力学性能优于工艺二;较高的熔融纺丝温度可提高纤维的拉伸强度、拉伸模量、熔点和结晶度;SEM分析表明,石墨烯较均匀地分散在PA6基体中,纤维表面均匀,无明显瑕疵。     

石墨烯/聚酰胺6纤维的混合熔融纺丝工艺及性能

采用溶液混合冷冻干燥法制备了质量分数0.004%的石墨烯/聚酰胺6(PA6)粒料,再用2种工艺制备石墨烯/PA6纤维——石墨烯/PA6粒料直接熔融纺丝;石墨烯/PA6粒料加入双螺杆挤出机熔融混合、挤出、造粒、熔融纺丝。用万能试验机测试了纤维的拉伸性能;用差示扫描量热分析测试了纤维的熔融行为并计算了结晶度;用扫描电镜(SEM)观察了石墨烯/PA6纤维的微观形态。研究结果表明,微量石墨烯的加入能够显著改善PA6纤维的拉伸性能,制备的石墨烯/PA6纤维的拉伸强度和拉伸模量分别可达到270 MPa和9.4GPa;工艺一制备的石墨烯/PA6纤维的热力学性能优于工艺二;较高的熔融纺丝温度可提高纤维的拉伸强度、拉伸模量、熔点和结晶度;SEM分析表明,石墨烯较均匀地分散在PA6基体中,纤维表面均匀,无明显瑕疵。     

同轴静电纺丝玉米醇溶蛋白和聚环氧乙烷不同核壳纤维的性能

通过同轴静电纺丝技术,研发出可以负载功能因子的可食性纳米材料。对玉米醇溶蛋白(Zein)和聚环氧乙烷(PEO)进行静电纺丝制备纤维膜,采用扫描电镜(SEM)和透射电镜(TEM)对筛选出4种合适纳米纤维膜的微观形貌进行观察,同时作出了傅里叶变换红外光谱(FT-IR)分析,SEM、TEM和FT-IR都充分证明了纳米纤维膜的成功封装。纳米纤维膜的热特性、力学性能和细胞黏附性分析表明,在以共混的纳米纤维中,Zein/PEO包PEO和Zein/PEO包Zein的纤维纳米结构更理想。表现出共混的纳米纤维PEO含量多的能使其拉伸强度增强,同时含PEO的纳米纤维表面细胞位点多,其细胞的黏附性增加。     

静电纺制备的PLLA/PCL复合支架性能及细胞相容性

利用静电纺丝技术制备了一系列不同比例的左旋聚乳酸/聚己内酯(PLLA/PCL)复合纳米纤维支架。通过扫描电镜、差热分析、宽角X射线衍射和接触角测试手段对支架结构与形态、结晶性能及亲水性进行了表征;采用在缓冲溶液中加酶的方式,研究了复合材料的降解性能;将体外培养的真皮成纤细胞接种至材料表面,用扫描电镜观察了成纤细胞在材料表面的生长情况。研究结果表明,电纺丝得到的复合支架纤维直径均一,且呈相互连通的多孔网状结构;脂肪酶的存在加速了支架材料的降解速度;成纤细胞在复合支架上具有良好的生长状态。     

KGM/明胶/nano HAP椎间盘纤维环组织工程支架的制备与研究

椎间盘退变性疾病已经成为严重影响人们工作和生活的疾病,生物组织工程技术的出现为椎间盘疾病的治疗提供了新的思路和方法。本研究以魔芋葡甘聚糖(Konjac Glucomannan,KGM)、明胶和纳米羟基磷灰石(nano HAP)为原料,分别采用湿法纺丝法和卷膜法构建了椎间盘纤维环组织工程支架。采用扫描电子显微镜(SEM)、X射线衍射仪(XRD)和傅里叶变换红外光谱仪(FT-IR)对支架的成分、结构和形貌进行了分析,并测试了纤维环支架的抗压强度、吸水率、孔隙率、体外降解性及细胞毒性。实验结果表明,得到的椎间盘纤维环组织工程支架具有各向异性的结构特点,与天然椎间盘纤维环结构极为类似,且为多孔结构。支架中加入nano HAP可以提高其强度;湿法纺丝法比卷膜法制备的纤维环支架强度高;戊二醛交联比氨水交联的纤维环支架强度高,但降解速率快;此外,采用戊二醛作交联剂可对nano HAP进行更好的包裹,从而更好地提高支架的强度。支架的吸水率均在700%以上,孔隙率为66%~75%。该研究为研发新型椎间盘纤维环组织工程支架材料提供了一种思路以及一定的实验和理论依据。     

PLGA/TSF静电纺纳米纤维的仿生矿化及生物相容性

利用静电纺丝和模拟体液仿生矿化技术制备了聚乳酸-羟基乙酸共聚物/柞蚕丝素/羟基磷灰石((PLGA/TSF/HA)骨组织工程复合支架。通过扫描电子显微镜(SEM)、透射电子显微镜(TEM)、X射线衍射测试(XRD)和热重分析(TG)对复合纳米纤维的形貌结构进行了表征。此外,在复合纳米纤维支架材料上接种人骨髓间充质干细胞(hMSCs),通过四甲基偶氮噻唑蓝比色(Four methyl azo thiazole blue colorimetric,MTT)法,观察细胞在材料表面的生长情况评价纳米纤维的生物相容性。结果显示,PLGA/TSF纳米纤维毡具有精细的三维结构,纤维直径分布均匀,表面光滑。矿化后HA颗粒均匀地分布在PLGA/TSF纳米纤维表面,矿物含量约占63%。与PLGA/TSF纳米纤维支架相比,PLGA/TSF/HA纳米纤维支架的亲水性、生物相容性都得到显著提高。     

取向TSF/PLLA静电纺纳米纤维毡的制备及其生物相容性

利用静电纺丝技术制备了取向的柞蚕丝素/左旋聚乳酸(TSF/PLLA)纳米纤维毡。通过扫描电子显微镜(SEM)、X射线衍射分析(XRD)和拉伸测试分别对TSF/PLLA纳米纤维的形貌、结晶结构及力学性能进行了研究。将人成骨肉瘤细胞(MG-63)种植在TSF/PLLA纳米纤维上,通过荧光显微镜分析和MTT(四甲基偶氮噻唑蓝比色法),观察细胞在材料表面的生长情况,评价纳米纤维的生物学性能。结果表明,TSF含量为10%时,纤维直径分布均匀,结晶度高。但是,TSF含量超过10%后,纤维直径粗细不匀明显,纤维的力学性能下降。与无规纤维毡相比,取向的纳米纤维毡力学性能优异,初始模量高,更能够促进细胞增殖,对细胞的生长行为影响大。     

改性大麻纤维/不饱和聚酯复合材料的力学性能及界面表征

采用模压成型方法制备大麻纤维/不饱和聚酯复合材料,用六亚甲基二异氰酸酯(DIH)与丙烯酸羟乙酯(HEA)对纤维进行表面处理。结果表明,纤维改性后复合材料的拉伸强度、弯曲强度及弯曲模量均有显著提高;当DIH-HEA用量为纤维干质量的3%时,复合材料的总体力学性能最佳。复合材料拉伸断面扫描电镜(SEM)显示,纤维表面处理改善了纤维与树脂间的界面结合。改性纤维的红外光谱(FT-IR)和X射线光电子能谱(XPS)分析表明,DIH-HEA混合物与纤维表面羟基产生共价键结合。     

Comparative performance of collagen nanofibers electrospun from different solvents and stabilized by different crosslinkers

Collagen electrospun scaffolds well reproduce the structure of the extracellular matrix (ECM) of natural tissues by coupling high biomimetism of the biological material with the fibrous morphology of the protein. Structural properties of collagen electrospun fibers are still a debated subject and there are conflicting reports in the literature addressing the presence of ultrastructure of collagen in electrospun fibers. In this work collagen type I was successfully electrospun from two different solvents, trifluoroethanol (TFE) and dilute acetic acid (AcOH). Characterization of collagen fibers was performed by means of SEM, ATR-IR, Circular Dichroism and WAXD. We demonstrated that collagen fibers contained a very low amount of triple helix with respect to pristine collagen (18 and 16 % in fibers electrospun from AcOH and TFE, respectively) and that triple helix denaturation occurred during polymer dissolution. Collagen scaffolds were crosslinked by using 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC), a commonly employed crosslinker for electrospun collagen, and 1,4-butanediol diglycidyl ether (BDDGE), that was tested for the first time in this work as crosslinking agent for collagen in the form of electrospun fibers. We demonstrated that BDDGE successfully crosslinked collagen and preserved at the same time the scaffold fibrous morphology, while scaffolds crosslinked with EDC completely lost their porous structure. Mesenchymal stem cell experiments demonstrated that collagen scaffolds crosslinked with BDDGE are biocompatible and support cell attachment.     

Investigation of 2D and 3D electrospun scaffolds intended for tendon repair

Two-dimensional (2D) electrospun fibre mats have been investigated as fibrous sheets intended as biomaterials scaffolds for tissue repair. It is recognised that tissues are three-dimensional (3D) structures and that optimisation of the fabrication process should include both 2D and 3D scaffolds. Understanding the relative merits of the architecture of 2D and 3D scaffolds for tendon repair is required. This study investigated three different electrospun scaffolds based on poly(ε-caprolactone) fibres intended for repair of injured tendons, referred to as; 2D random sheet, 2D aligned sheet and 3D bundles. 2D aligned fibres and 3D bundles mimicked the parallel arrangement of collagen fibres in natural tendon and 3D bundles further replicated the tertiary layer of a tendon’s hierarchical configuration. 3D bundles demonstrated greatest tensile properties, being significantly stronger and stiffer than 2D aligned and 2D random fibres. All scaffolds supported adhesion and proliferation of tendon fibroblasts. Furthermore, 2D aligned sheets and 3D bundles allowed guidance of the cells into a parallel, longitudinal arrangement, which is similar to tendon cells in the native tissue. With their superior physical properties and ability to better replicate tendon tissue, the 3D electrospun scaffolds warrant greater investigation as synthetic grafts in tendon repair.     

Uniaxially aligned electrospun fibers for advanced nanocomposites based on a model PVOH-epoxy system

This work demonstrates the potential of aligned electrospun fibers as the sole reinforcement in nanocomposite materials. Poly(vinyl alcohol) and epoxy resin were selected as a model system and the effect of electrospun fiber loading on polymer properties was examined in conjunction with two manufacturing methods. A proprietary electrospinning technology for production of uniaxially aligned electrospun fiber arrays was used. A conventional wet lay-up fabrication method is compared against a novel, hybrid electrospinning–electrospraying approach. The structure and thermomechanical properties of resulting composite materials were examined using scanning electron microscopy, dynamic mechanical analysis, thermogravimetric analysis, differential scanning calorimetry, Fourier transform infrared spectroscopy, and tensile testing. The results demonstrate that using aligned electrospun fibers significantly enhances material properties compared to unreinforced resin, especially when manufactured using the hybrid electrospinning–electrospraying method. For example, tensile strength of such a material containing only 0.13 vol% of fiber was increased by ∼700%, and Young’s modulus by ∼250%, with concomitant increase in ductility.     

Emulsion electrospun nanofibers as substrates for cardiomyogenic differentiation of mesenchymal stem cells

The potential of cardiomyogenic differentiation of human mesenchymal stem cells (hMSCs) on emulsion electrospun scaffold containing poly(l-lactic acid)-co-poly-(ε-caprolactone), gelatin and vascular endothelial growth factor (PLCL/GV) was investigated in this study. The characterizations of the scaffold were carried out using scanning electron microscope (SEM), transmission electron microscope, water contact angle and porometer. The proliferation of hMSCs showed that 73.4 % higher cell proliferation on PLCL/GV scaffolds than that on PLCL scaffold after 20 days of cell culture. Results of 5-chloromethylfluorescein diacetate staining and SEM morphology analysis indicated that hMSCs differentiated on PLCL/GV scaffolds showed irregular morphology of cardiomyocyte phenotype compared to the typical long and thin hMSC phenotype. Immunostaining results showed the expression of alpha actinin and myosin heavy chain. Our studies identified emulsion electrospinning as a method for fabrication of core–shell fibers suitable for the differentiation of stem cells to cardiac cells, with potential application in cardiac regeneration.     

Evaluation of electrospun fibrous scaffolds of poly(dl-lactide) and poly(ethylene glycol) for skin tissue engineering

This study is derived from the innate concerns of electrospun poly(DL-lactide) (PDLLA) fibers as tissue engineering scaffolds: hydrophobic surface, surface erosion and dimensional shrinkage, which are not favorable to trigger the initial adhesion and further growth and population of cells. Blending electrospinning of PDLLA and poly(ethylene glycol) (PEG) with different PEG contents was evaluated for optimal tissue engineering scaffolds. The surface hydrophilicity was improved, and the degradation patterns of PDLLA/PEG mats changed from surface erosion to bulk degradation with the increase in PEG contents. The dimensional shrinkage was alleviated through the formation of crystal regions of PEG in the fiber matrix. The PDLLA/PEG fibrous mats were slightly weakened with the increase in the PEG contents, but a significant decrease in the tensile strength could be found for those with PEG contents of over 40%. Human dermal fibroblasts (HDFs) interacted and integrated well with the surrounding fibers containing 20 and 30% PEG, which provided significantly better environment for biological activities of HDFs than electrospun PDLLA mats. It indicated that electrospun mats containing 30% PEG exhibited the most balanced properties, including moderately hydrophilic surface, minimal dimensional changes, adaptable bulk biodegradation pattern and enhancement of cell penetration and growth within fibrous mats.     

The influence of surface nanoroughness of electrospun PLGA nanofibrous scaffold on nerve cell adhesion and proliferation

Electrospun nanofibrous scaffolds in neural tissue engineering provide an alternative approach for neural regeneration. Since the topography of a surface affects the microscopic behaviour of material; the creation of nanoscale surface features, which mimic the natural roughness of live tissue, on polymer surfaces can promote an appropriate cell growth and proliferation. In this research, a unique PLGA nanofibrous structure was fabricated without any post-electrospinning treatment. Scaffolds were prepared in two general groups: cylindrical and ribbon-shaped electrospun fibres, with smooth and rough (porous and grooved) surfaces. The experiments about nerve cell culture have demonstrated that the nanoroughness of PLGA electrospun scaffolds can increase the cell growing rate to 50 % in comparison with smooth and conventional electrospun scaffolds. SEM and AFM images and MTT assay results have shown that the roughened cylindrical scaffolds enhance the nerve growth and proliferation compared to smooth and ribbon-shaped nanofibrous scaffolds. A linear interaction has been found between cell proliferation and surface features. This helps to approximate MTT assay results by roughness parameters.     

Biocompatibility evaluation of protein-incorporated electrospun polyurethane-based scaffolds with smooth muscle cells for vascular tissue engineering

Nanotechnology has enabled the engineering of a variety of materials to meet the current challenges and needs in vascular tissue regeneration. In this study, four different kinds of native proteins namely collagen, gelatin, fibrinogen, and bovine serum albumin were incorporated with polyurethane (PU) and electropsun to obtain composite PU/protein nanofibers. SEM studies showed that the fiber diameters of PU/protein scaffolds ranged from 245 to 273 nm, mimicking the nanoscale dimensions of native ECM. Human aortic smooth muscle cells (SMCs) were cultured on the electrospun nanofibers, and the ability of the cells to proliferate on different scaffolds was evaluated via a cell proliferation assay. Cell proliferation on PU/Coll nanofibers was found the highest compared to other electrospun scaffolds and it was 42 % higher than the proliferation on PU/Fib nanofibers after 12 days of cell culture. The cell–biomaterial interaction studies by SEM confirmed that SMCs adhered to PU/Coll and PU/Gel nanofibers, with high cell substrate coverage, and both the scaffolds promoted cell alignment. The functionality of the cells was further demonstrated by immunocytochemical analysis, where the SMCs on PU/Coll and PU/Gel nanofibers expressed higher density of SMC proteins such as alpha smooth muscle actin and smooth muscle myosin heavy chain. Cells expressed biological markers of SMCs including aligned spindle-like morphology on both PU/Coll and PU/Gel with actin filament organizations, better than PU/Fib and PU/BSA scaffolds. Our studies demonstrate the potential of randomly oriented elastomeric composite scaffolds for engineering of vascular tissues causing cell alignment.     

Fabrication of PU/PEGMA crosslinked hybrid scaffolds by in situ UV photopolymerization favoring human endothelial cells growth for vascular tissue engineering

Poly(ethylene glycol) methacrylate (PEGMA) was introduced into a polyurethane (PU) solution in order to prepare electrospun scaffold with improving the biocompatibility by electrospinning technology for potential application as small diameter vascular scaffolds. Crosslinked electrospun PU/PEGMA hybrid nanofibers were fabricated by a reactive electrospinning process with N,N'-methylenebisacrylamide as crosslinker and benzophenone as photoinitiator. The photoinduced polymerization and crosslinking reaction took place simultaneously during the electrospinning process. The electrospinning solutions with various weight ratios of PU/PEGMA were successfully electrospun. No significant difference in the scaffold morphology was found by SEM when PEGMA content was <20 wt%. The crosslinked fibrous scaffolds of PU/PEGMA exhibited higher mechanical strength than the pure PU scaffold. The hydrophilicity of scaffolds was controlled by varying the PU/PEGMA weight ratio. The tissue compatibility of electrospun nanofibrous scaffolds were tested using human umbilical vein endothelial cells (HUVECs). Cell morphology and cell proliferation were measured by SEM, fluorescence microscopy and thiazolyl blue assay (MTT) after 1, 3, 7 days of culture. The results indicated that the cell morphology and proliferation on the crosslinked PU/PEGMA scaffolds were better than that on the pure PU scaffold. Furthermore, the appropriate hydrophilic surface with water contact angle in the range of 55-75° was favorable of improvement the HUVECs adhesion and proliferation. Cells seeded on the crosslinked PU/PEGMA (80/20) scaffolds infiltrated into the scaffolds after 7 days of growth. These results indicated the crosslinked electrospun PU/PEGMA nanofibrous scaffolds were potential substitutes for artificial vascular scaffolds.     

热处理对电纺聚己内酯超细纤维形态和性能的影响

通过静电纺丝法制备出聚己内酯(PCL)超细纤维膜,并采用热处理方法使纤维间粘接。用扫描电镜、红外光谱仪、X射线衍射仪、差示扫描量热仪对热处理前后聚己内酯超细纤维进行表征,并进行了拉伸测试。结果表明,在55℃对电纺聚己内酯超细纤维热处理30min、60min后,纤维间有明显的粘接,热处理没有改变电纺聚己内酯超细纤维的分子结构和晶型,热处理后纤维的结晶度提高,纤维膜的力学性能有明显改善。     

Stem cell differentiation on electrospun nanofibrous substrates for vascular tissue engineering

Nanotechnology has enabled the engineering of a variety of materials to meet the current challenges and requirements in vascular tissue regeneration. In our study, poly-l-lactide (PLLA) and hybrid PLLA/collagen (PLLA/Coll) nanofibers (3:1 and 1:1) with fiber diameters of 210 to 430 nm were fabricated by electrospinning. Their morphological, chemical and mechanical characterizations were carried out using scanning electron microscopy (SEM), attenuated total reflectance Fourier transform infrared (ATR-FTIR), and tensile instrument, respectively. Bone marrow derived mesenchymal stem cells (MSCs) seeded on electrospun nanofibers that are capable of differentiating into vascular cells have great potential for repair of the vascular system. We investigated the potential of MSCs for vascular cell differentiation in vitro on electrospun PLLA/Coll nanofibrous scaffolds using endothelial differentiation media. After 20 days of culture, MSC proliferation on PLLA/Coll(1:1) scaffolds was found 256% higher than the cell proliferation on PLLA scaffolds. SEM images showed that the MSC differentiated endothelial cells on PLLA/Coll scaffolds showed cobblestone morphology in comparison to the fibroblastic type of undifferentiated MSCs. The functionality of the cells in the presence of ‘endothelial induction media’, was further demonstrated from the immunocytochemical analysis, where the MSCs on PLLA/Coll (1:1) scaffolds differentiated to endothelial cells and expressed the endothelial cell specific proteins such as platelet endothelial cell adhesion molecule-1 (PECAM-1 or CD31) and Von Willebrand factor (vWF). From the results of the SEM analysis and protein expression studies, we concluded that the electrospun PLLA/Coll nanofibers could mimic the native vascular ECM environment and might be promising substrates for potential application towards vascular regeneration.