Hippocampal Neuron-Derived Extracellular Matrix Coated Nanofibrous Scaffold for Neural Tissue Engineering

The aim of this study is to prepare poly-L-lactide( PLLA) electrospun nanofibrous scaffolds coated with hippocampal neuron-derived extracellular matrix( N-ECM)and construct a novel neural tissue engineering scaffold.Neonatal rat hippocampal neurons were seeded on PLLA nanofibers,and then decellularized to derive a cell-free extracellular matrix loaded N-ECM/PLLA modified scaffolds. The morphology and ingredients of N-ECM/PLLA were observed by scanning electron microscopy( SEM) and immunofluorescence staining respectively, and the cytocompatibility of the composite scaffolds was characterized by cell count kit-8( CCK-8) assay. The N-ECM was clearly identified loading on scaffolds when being imaged via SEM and immunofluorescence staining results showed that the N-ECM was made up of fibronectin and laminin. Most importantly, compared with tissue culture polystyrene and pure scaffolds, N-ECM/PLLA scaffolds could effectively facilitate the proliferation of rat adrenal neuroma cells( PC12 cells),indicating their better cell compatibilities. Based on the combination of N-ECM and PLLA biomaterials,the present study has fabricated a unique and versatile neural tissue engineering scaffold,offering a new thought for future neural tissue engineering.     

Dexamethasone-Loaded PLGA Microspheres Incorporated PLLA/PLGA/PCL Composite Scaffold for Bone Tissue Engineering

The combination of micro-carriers and polymer scaffolds as promising bone grafts have attracted considerable interest in recent decades.The poly(L-lactic acid)/poly(lactic-co-glycolic acid)/polycaprolactone(PLLA/PLGA/PCL)composite scaffold with porous structure was fabricated by thermally induced phase separation(TIPS).Dexamethasone(DEX)was incorporated into PLGA microspheres and then loaded on the PLLA/PLGA/PCL scaffoldtopreparethedesiredcompositescaffold.The physicochemical properties of the prepared composite scaffold were characterized.The morphology of rat bone marrow mesenchymal stem cells(BMSCs)grown on scaffolds was observed using scanning electron microscope(SEM)and fluorescence microscope.The resultsshowedthatthePLLA/PLGA/PCLscaffoldhad interconnected macropores and biomimetic nanofibrous structure.In addition,DEX can be released from scaffold in a sustained manner.More importantly,DEX loaded composite scaffold can effectively support the proliferation of BMSCs as indicated by fluorescence observation and cell proliferation assay.The results suggested that the prepared PLLA/PLGA/PCL composite scaffold incorporating drug-loaded PLGA microspheres could hold great potential for bone tissue engineering applications.     

Nanofibrous Scaffold Containing Osteoblast-Derived Extracellular Matrix for the Proliferation of Bone Marrow Mesenchymal Stem Cells

Extracellular matrix( ECM) plays a prominent role in establishing and maintaining an appropriate microenvironment for tissue regeneration. The aims of this study were to construct a tissue engineered scaffold by reconstituting osteoblast cell-derived ECM( O-ECM) on the electrospun nanofibrous scaffold,and further to evaluate its subsequent application for promoting the proliferation of bone marrow mesenchymal stem cells( BMSCs). To engineer a biomimetic scaffold, calvarial osteoblasts and electrospun poly-llactic acid( PLLA) nanofibers were prepared and subjected to decellularize for O-ECM deposition. To evaluate and characterize the O-ECM/PLLA scaffold, the morphology was examined and several specific mark proteins of osteoblasts matrix were evaluated.Furthermore,the cell counting kit-8( CCK-8) assay was used to detect the proliferation of the BMSCs cultivated on the O-ECM/PLLA scaffold. The results indicated O-ECM/PLLA scaffold was loaded with Collagen I, Fibronectin, and Laminin, as the composition of the marrow ECM. After decellularization,O-ECM deposition was observed in O-ECM/PLLA scaffold. Moreover,the O-ECM/PLLA scaffold could significantly enhance the proliferation of BMSCs,suggesting better cytocompatibility compared to the other groups tested. Taken together,a biomimetic scaffold based on the joint use of O-ECM and PLLA biomaterials,which represents a promising approach to bone tissue engineering, facilitates the expansion of BMSCs in vitro.     

Disc-Electrospun PCL Nanofiber Formed Micro-patterned Structure Scaffold

Disc-electrospinning using a disc as spinneret and a rotary drum as collector is a novel technology to prepare nanofiber which has been applied in tissue engineering scaffolds. In this study, nanofibrous mats with mlcro-patterned structure were fabricated via disc-electrospinning. Poly （ε-eaprolactone） （PCL） was dissolved in trifluoroethanol （TFE） at various concentrations （ 2 %-7 % ） （w/v） for electrospinning and the applied voltage ranged from 40 to 70 kV. Scanning electron microscopy （SEM） was employed to observe the morphology of the nanofibrous scaffolds. SEM images illustrated that the nanofibers with beads formed micro-patterned structure such as triangles and other polygons. The average diameter of nanofibers presented various size with the concentration increased from 2% to 7%. The beads on the nanofibers constructed the vertexes of the polygons, while nanofibers bridged between adjacent vertexes. The concentration of solution and applied voltage may be two dominant factors to influence the topological structure of the nanofibrons scaffolds. Cells cultured on the micro-patterned scaffold spread along the edges of the polygons. The scaffold with patterned structure may have a promising application in tissue engineering.     

功能化介孔二氧化硅微球的药物输送行为分析

介孔二氧化硅(MSNs)作为一类新型的药物载体在药物缓控释领域的应用方兴未艾。采用模板诱导和自组装方法合成MCM-41型介孔二氧化硅纳米颗粒,并通过聚乙二醇(PEG)的表面修饰,制备出一类具有高亲水性、高孔隙率、高比表面积的MSNs修饰微球。采用氮吸附(BET)、扫描电镜(SEM)、透射电镜(TEM)、粒径分析等手段表征并对比了聚乙二醇(PEG)修饰前后的MSNs基础理化性能。在此基础上,选用阿霉素作为模型药物,包埋于介孔材料中,对比了PEG修饰前后MSNs中阿霉素的装载量、包封率及释放行为。选用乳腺癌细胞MCF-7为模型癌细胞,选用人血清蛋白(HAS)作为模型蛋白,考察了两种材料对细胞的生物安全性及对蛋白的吸附情况,并将两种材料所对应的载药微球与MCF-7进行共培养,探究两种载药系统对癌细胞的灭杀情况。     

电纺聚-L-乳酸/β-磷酸三钙复合物纳米纤维膜

利用静电纺丝法制备了生物可吸收聚-L-乳酸(PLLA)/β-磷酸三钙(β-TCP)复合物纳米纤维膜.采用扫描电子显微镜(SEM)、场发射扫描电子显微镜(FESEM)等手段研究了复合物纳米纤维膜的结构和形态,详细探讨电纺工艺条件对制备PLLA/β-TCP复合物纳米纤维的形态影响.通过拉伸力学测试、噻唑蓝比色法(MTT)对复合物纳米纤维膜的力学性能和体外细胞相容性作了进一步研究.结果表明,PLLA/β-TCP复合物纳米纤维的几何结构与电纺条件有关,随着聚合物溶液浓度增加、溶液流速增大,纤维直径有不同程度的增大;复合物纳米纤维膜的拉伸强度和杨氏模量随β-TCP的含量增加而下降;复合物纳米纤维膜对L-929细胞系无细胞毒性,显示良好的细胞相容性.     

Green Electrospun Silk Fibroin/Galactose Chitosan Composite Nanofibrous Scaffolds for Hepatic Tissue Engineering

The electrospun nanofibrous scaffolds made of proteins and polysaccharides were thought to be able to simulate the structure of natural extracellular matrix well.Silk fibroin(SF)and chitosan(CS)are probably the most widely used natural materials in biomedical fields including liver tissue engineering for their good properties and wide variety of sources.The asialoglycoprotein receptors of hepatocyte were reported to specifically recognize and interact with galactose.In this work,a green electrospun SF/galactosylated chitosan(GC)composite nanofibrous scaffold was fabricated and characterized.The data indicated that the addition of GC greatly influenced the spinning effect of SF aqueous solution,and the average diameter of the composite nanofibers was about 520nm.Moreover,the green electrospun SF/GC nanofibrous scaffolds were demonstrated significantly enhancing the adhesion and proliferation of hepatocyte(RH35)according to our data.The present study did a useful exploration on constructing scaffolds for liver regeneration by green electrospinning,and also laid a good foundation for the further applicative research of this green electrospun scaffolds in liver tissue engineering.     

仿生增强制备聚乳酸基骨组织工程复合材料

依据仿生原理制备了纳米羟基磷灰石聚乳酸(nHA-PLA)复合的骨框架材料.此复合材料中的主要成分是纳米羟基磷灰石,纳米相的羟基磷灰石就是天然骨中主要的无机相.在保持高孔隙率(90%)的同时,复合材料的抗压性能达到2.07 MPa,高于单纯的聚乳酸框架材料(为0.89 MPa).分离成骨细胞并在三维框架材料上培养,用扫描电镜进行观察,复合材料具有很好的细胞贴附性能.仿生制备的三维纳米羟基磷灰石聚乳酸复合骨框架材料,无论从结构还是性能上,都是骨组织工程中的优选材料之一.     

不同粒径高度有序的介孔二氧化硅纳米材料（MSNs）的制备与表征

通过调解正硅酸乙酯(TEOS)和NH₃·H₂O的加入量,  采用共沉淀法可控地制备了一系列不同粒径（80~320 nm）, 且具有规则孔道结构的介孔二氧化硅纳米材料（MSNs）, 并利用小角X射线衍射（SAXRD）、 透射电镜（TEM）、 扫描电镜(SEM)及N2[KG-*3]吸附 脱附等方法对产物进行表征. 实验结果表明: 合成的样品均具有高度有序的孔道结构, 为典型的MCM 41介孔二氧化硅纳米材料; 采用合成后水热处理方法可提高材料的有序性和稳定性.     

Immobilization of biomacromolecules on poly-L-lactide surface via a layer-by-layer method for the improving of its cytocompatibility to bone marrow stromal cells

Hyaluronic acid （HA） and chitosan （CS） were immobilized on the surface of poly-L-lactide （PLLA） by the following procedure： Firstly, PLLA was aminolyzed with 1, 6-hexanediamine, and part of the PLLA surface ester groups were converted to free amino groups. Then negatively charged hyaluronic acid and positively charged chitosan were deposited onto the surface of aminolyzed PLLA film in a layer-by-layer assembly manner. The effect of the layer-by- layer deposition was evaluated by ATRoFTIR spectroscopy, Raman spectroscopy and static contact angle measurements. The cytocompatibility of PLLA sample to bone marrow stromal cells （BMSCs） was improved after modification with chitosan and HA. The cell attachment, activity, and proliferation on CS/HA modified PLLA films were enhanced comparing with the control. The cells cultured on the modified PLLA samples excreted abundant cytoplasm and can differentiate to vascular smooth muscle （SM）-like （SM-like） cells. A macroporous three-dimensional PLLA scaffold was prepared by integrating both the technique of freeze-drying and particle leaching. Layer-by-layer modification by HA/CS and cell culture was also applied on this scaffold. The scaffold cultured with BMSCs for 2 weeks has been tested successfully in vivo as a patch for repairing the artificial incision on canine pulmonary artery.     

新型前交叉韧带支架材料的构建及其生物相容性的实验研究

探讨以聚羟基丁酸己酯/聚左旋乳酸(PHB/PLLA1∶1)胶原杂化支架作为前交叉韧带组织工程载体材料的可行性。制备"三明治"样结构PHB/PLLA共聚物并测量其孔隙率等指标。以I型胶原对制备的PHB/PLLA支架进行杂化,获得PHB/PLLA胶原杂化支架。扫描电镜观察其表面结构。将兔皮肤成纤维细胞(SF)接种于PHB/PLLA胶原杂化支架,共培养5d后,扫描电镜下观察其在材料上生长情况。PHB/PLLA支架杂化后胶原填充于纤维空隙,分布比较均匀。体外培养的皮肤成纤维细胞成功种植在支架材料上,在材料上粘附、生长良好。说明构建的支架材料具有良好的三维构型和生物相容性,有望为前交叉韧带损伤的修复提供了一种新型的支架材料。     

A novel injectable fibroblasts-porous PDLLA microspheres/collagen gel composite for soft-tissue augmentation

This study designed a novel porous PDLLA microspheres/collagen gel composite combined with fibroblasts as the injectable dermal filler for soft-tissue augmentation. The low degradation rate of porous PDLLA microspheres and seed cells were introduced in the system to achieve the filling volume stability and stronger regeneration activity. Biodegradable PDLLA porous microspheres were prepared by an improved water-in-oil-in-water double emulsion solvent evaporation method. The combine of fibroblasts with porous microspheres was observed through co-culture of cells with microspheres, SEM (scanning electron microscope) and fluorescent staining technology. The MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay, the hemolysis test and histocompatibility experiment indicated that the composite had satisfactory biocompatibility in vitro and in vivo. In the animal studies, the composite was implanted into the subcutaneous part of the rats’ back through sterile needles. The collagen was metabolized within 30 days, meanwhile, fibroblasts-porous PDLLA microspheres served as scaffold structure and seed cells which promote new connective tissue formation. The histopathological studies demonstrate that the fibroblasts-porous PDLLA microspheres/collagen gel composite group could create larger amount of supportive structure than PDLLA porous microspheres/collagen gel composite group. All the results indicate that fibroblasts-porous PDLLA microspheres/collagen gel composite may have great clinical application in soft-tissue augmentation with its excellent biocompatibility, regeneration activity and stable long-term filling ability.     

Preparation and cytocompatibility of polylactic acid/hydroxyapatite/graphene oxide nanocomposite fibrous membrane

A series of polylactic acid (PLA) based nanocomposite fibrous membranes,including neat PLA,PLA/hydroxyapatite (HA) and PLA/HA/graphene oxide (GO),were fabricated via electrospinning method.The morphology and composition were investigated by scanning electron microscopy (SEM),X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) respectively.The thermal stability was determined by thermogravimetric analysis (TGA).To estimate the cytocompatibility of asprepared PLA/HA/GO fibrous membrane,MC3T3-E1 cells were cultured,and the corresponding cell adhesion and differentiation capability were investigated by fluorescence microscopy,SEM and MTT test.The electrospun ternary PLA/HA/GO membrane exhibited three-dimensional fibrous structure with relatively rough surface morphology,which made itself ideal for cell attachment and proliferation in bone tissue regeneration.The fluorescence microscopy,SEM and MTT test confirmed that the PLA/HA/GO nanocomposite fibrous membrane created a proper environment for the seeding and proliferation of MC3T3-E1 cells.     

Polypyrrole-coated styrene-butyl acrylate copolymer composite particles with tunable conductivity

A series of near or monodisperse styrene-butyl acrylate (SBA) copolymer latex particles with different butyl acrylate contents were coated with polypyrrole. The structure of the SBA/PPy composites was characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), diffuse reflectance infrared Fourier transform spectroscopy (DRIFT), X-ray photoelectron spectroscopy (XPS), differential scanning calorimetry (DSC) andstandard fourprobe method. The core-shell morphology of the SBA/PPy composite particles was confirmed. The result of DSC showed that TR of the composite is mainly determined by the core component. The effects of the concentration of polypyrrole, the butyl acrylate content in SBA copolymer and the nature of the counter-anion on the electrical conductivity of compression-moulded samples were studied. It was first found that the electrical conductivity of the samples can be tuned by varying the butyl acrylate content in SBA copolymer and the highest conductivity of the core-shell composite was 0.17 S. cm^-1     

透明质酸改性PHBV组织工程纳米纤维支架的研究

组织工程支架材料表面性质对细胞的黏附起着重要作用,进而影响细胞的增殖、分化等一系列生长过程.本研究采用天然生物大分子透明质酸(hyaluronic acid,HA)对聚(3-羟基丁酸酯-co-3-羟基戊酸酯)(Poly(3-hydroxybutyrate-co-3-hydroxyvalerate),PHBV)进行表面修饰以提高材料的表面生物活性.首先通过静电纺丝法制备PHBV纳米纤维支架,利用1,6-己二胺胺解在PHBV表面引入自由胺基,并以此为反应活性位点在水溶性的碳化二亚胺/N-羟基琥珀酰亚胺缩合剂体系中将透明质酸固定接枝在PHBV表面.SEM结果表明,静电纺丝制备的PHBV纳米纤维支架表面平滑程度高,纤维直径分布较均匀,且没有串珠;FTIR证明1,6-己二胺改性及透明质酸接枝改性PHBV纳米纤维支架材料均成功实现;茚三酮法表明PHBV表面胺基密度随胺解时间增加而增大,在胺解约50min时达到最大值;水接触角法表明固定接枝透明质酸后,表面亲水性明显改善;细胞实验表明透明质酸改性的PHBV纳米纤维支架可显著促进软骨细胞的体外增殖.综上所述,透明质酸改性的PHBV纳米纤维支架可望应用于软骨组织工程领域.     

Electrochemical behavior of different shelled microcapsule composite copper coatings

Copper/liquid microcapsule composite coatings with polyvinyl alcohol (PVA), gelatin or methyl cellulose (MC) as shell materials were prepared by electrodeposition. The influence of shell materials on the corrosion resistance of the composite coatings in 0.1 M H₂SO₄ was investigated by means of electrochemical techniques, scanning electron microscopy (SEM), and energy dispersion spectrometry (EDS). The results show that the participation of microcapsules can enhance the corrosion resistance of the composite coatings compared with the traditional copper layer. Based on the analysis of electrochemical test results, the release ways of microcapsules were deduced. Gelatin and MC as the shell materials of microcapsules are easy to release quickly in the composite coating. On the contrary, the releasing speed of PVA microcapsules is relatively slow due to their characteristics.     

MnO2/C复合纳米纤维纱线的制备及其导电性能

采用共轭静电纺丝法制备聚丙烯腈(PAN)纳米纤维纱线,并在不同温度下将PAN纳米纤维碳化得到碳纳米纤维纱线。以KMnO 4为锰源,通过水热合成法在碳纳米纤维纱线上原位生长纳米二氧化锰(MnO 2),形成MnO 2/C复合纳米纤维纱线,分别采用傅里叶变换红外光谱(FTIR)、扫描电子显微镜(SEM)、场发射扫描电子显微镜(FE-SEM)、数字万用表对碳纳米纤维纱线和MnO 2/C复合纳米纤维纱线的化学组成、表观形貌、电学性能等进行表征,并分析碳化温度对碳纳米纤维纱线的形貌和电学性能的影响,以及水热反应中盐酸浓度对纳米MnO 2形貌和MnO 2/C复合纳米纤维纱线的影响。结果表明:碳化温度越高,得到的纱线表面越光洁,石墨化程度越高,电学性能也越好,1000℃碳化工艺得到的碳纳米纤维纱线电导率最高,为31.5 S/cm;与MnO 2复合后的碳纳米纤维纱线电导率大幅下降,当盐酸与高锰酸钾摩尔浓度比为4∶1时得到的复合纳米纤维纱线的电导率最高,为0.1200 S/cm。     

聚乳酸/聚环氧乙烷纳米纤维膜的结构与性能表征

采用静电纺丝方法制备了聚乳酸(PLLA)/聚环氧乙烷(PEO)纳米纤维膜,利用扫描电子显微镜(SEM)、差示扫描量热(DSC)、X-射线衍射(XRD)和拉伸测试,对PLLA/PEO纳米纤维膜的形貌、结构、结晶行为和力学性能进行了表征,探究了PEO的质量分数对PLLA/PEO纳米纤维膜的结构、结晶行为和力学性能的影响。结果表明,PEO的加入,降低了PLLA/PEO纳米纤维膜的平均直径和直径分布宽度,提高了纤维的结晶速度、结晶度及断裂伸长率;PEO分子可提高聚乳酸分子链的运动能力和降低纤维的取向度,从而降低因取向引起的中间相含量,提高结晶相含量,进而改善聚乳酸纤维的结晶性能和韧性。     

Fabrication of PEI-Liposome Loaded Fish Gelatin Nanofibers Mats by Green Electrospinning

Polyethyleneimine （PEI） and cationic liposomes were widely used for gent delivery and the combination of PEI and liposome was reported to result in a higher efficiency of cell transfection in vitro. In recent years, better transfection was observed for the drug-loaded iiposome fixed on the tissue engineering scaffolds via embedding, surface adsorption or covalent grafting thus protected and bound by the scaffolds. In the present study, a novel PEI-liposome loaded fish gdatin composite nanofiber was successfully fabricated by a green electrosplnning process. The existence of PEI- liposome in the composite nanofibers was determined by Fourier transform infrared （ FTIR ） spectra, transmission electron microscopy （TEM）, and confoeal laser scanning microscopy （CLSM）. As shown by scanning electron microscopy （SEM）, the dectrospun composite nanofibers with uniform diameter were smooth and round, and the morphology of the fish gelatin fibers did not change significantly after the incorporation of PEI-liposomes. The transfection results in vitro suggest PEI-liposome loaded fish gelatin material may have a promising application in non-viral gene delivery systems.     

Deposition of crackless freestanding diamond films on Mo substrates with Zr interlayer

The Mo substrate with Zr interlayer, namely composite substrate, was employed to solve the problem of crack formation in the freestanding diamond film deposition. Freestanding diamond films deposited on the composite substrates by the direct current arc plasma jet chemical vapor deposition (CVD) method were investigated with scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and Raman spectroscopy. In addition, the stress distribution during the large area freestanding diamond film deposition on the composite substrate was analyzed based on the finite element model ANSYS. The results reveal that Zr interlayer can be easily destroyed during the post-deposition cooling process, which is helpful for stress release and crack avoiding in diamond films.