仿生制备的再生丝素蛋白水溶液的静电纺丝(Ⅰ)——工艺参数及结构特性

制备出了与蚕腺体内纺丝液浓度和后部丝腺pH值相近的再生丝素蛋白水溶液,利用静电纺丝技术模仿蚕在空气中吐丝的过程得到了再生丝素蛋白纤维.所得纤维的直径在350～4200nm之间,平均直径1700nm.通过正交实验方法考察了各种因素对纤维形态、直径及直径分布的影响,结果表明:所施电压对纤维的形态影响最大;溶液浓度对纤维的直径影响最大;喷头与接受板间距离对纤维直径的分布影响最大.实验得出了一个较好的静电纺丝条件为浓度30%,电压40kV,喷头与接受板间距离20cm.采用拉曼光谱、X衍射、DSC对再生丝素蛋白纤维进行了表征,发现再生丝素蛋白纤维中含有少量的Silk I结晶结构,主要以无定形结构为主,这与天然蚕丝的半结晶结构相比尚有差异.     

同轴静电纺再生丝素/丝胶蛋白纤维的制备及其形态结构表征

模仿蚕丝的组成和结构,利用同轴静电纺丝法制备了以再生丝素蛋白（RSF）为＂芯＂、丝胶蛋白（SS）为＂皮＂的双组分静电纺纤维。通过扫描电镜和透射电镜研究了内层纺丝液流速（Qc）、电压（U）、接收距离（D）以及场强（E）等参数对同轴静电纺RSF/SS纤维形态结构的影响。研究结果表明纤维的平均直径在1400～2100nm左右,皮-芯层结构清晰;Qc对纤维皮-芯层结构的影响较大,过大的内层纺丝液流速会因外层丝胶对内层丝素的包裹不均匀而导致偏芯现象;随E的增加（U增加或D减小）,纤维的直径及其分布显著减小,皮-芯层结构清晰;相同E下,高电压、长距离利于纤维的细化,使直径变细且分布均匀,皮-芯层结构明显。     

静电纺再生丝素纳米纤维:纤维直径分布与力学性能

采用静电纺丝的方法研制了再生丝素纳米纤维(ERSF)膜,纤维直径为50～1000nm.将脱胶后的桑蚕丝溶解在摩尔比为1:2:8 的60℃CaCl2/CH3CH2OH/H2O三元体系中,将该溶液冷冻干燥后溶解在98%的甲酸中得到再生丝素溶液,对其进行静电纺丝.研究了不同纺丝条件下,静电纺再生丝素纤维的直径分布.研究发现:在一定的电压和喷丝头与接收屏的距离(C-D)下,7wt%是具有良好可纺性的临界浓度.纤维的直径随着溶液浓度的增加而增大,随着C-D的增加而减小,并且在C-D较大时可以获得较均匀的纤维.电压是另一个影响纤维直径的重要因素,当电压高于某一数值时,可以纺得细而均匀的纳米级再生丝素纤维.在9wt%,12cm C-D and 15KV 的纺丝条件下,80%的纤维直径在50～150nm之间.由于所纺得的再生丝素纤维膜在水中会产生收缩,因此用甲醇和丙酮对其进行处理.力学性能是影响纤维膜实际使用的重要性能,我们测定和分析了静电纺再生丝素纤维膜处理前后的力学性能.     

聚乳酸的静电纺丝行为及其纤维结构研究

用静电纺丝法制备了纤维平均直径为350～1900nm的聚乳酸纤维,用扫描电镜研究了纤维的形貌,并用实验设计方法研究了纺丝工艺参数(溶液浓度、电场电压)对纤维平均直径的影响,同时用差示扫描量热分析和X射线衍射研究了静电纺丝所得纤维的结构.研究结果表明:溶液浓度对纤维的平均直径有较大的影响,溶液浓度较低时易形成珠状结构的纤维,纤维的平均直径随着聚合物浓度的增大而增大,并随电场电压的增大而减小.与浇铸膜相比,静电纺丝所制得的纤维有较低的结晶度,并且结晶结构不够完善.由静电纺丝制备的聚乳酸纳米纤维膜在组织工程和药物缓释等领域有潜在的应用前景.     

仿生制备的再生丝素蛋白水溶液的静电纺丝(Ⅲ)-金属离子的影响

通过添加在家蚕丝腺体中含量较多的钾、钙、镁3种金属离子,研究了不同种类的金属离子对丝素蛋白水溶液的流变性能及静电纺丝的影响.研究结果表明,添加K 后溶液的表观粘度较大,而含Ca2 和Mg2 的丝素溶液粘度较小;分别加入0.225mol/L K 、Ca2 和Mg2 后,再生丝素蛋白水溶液在pH为6.0浓度为30%时都可通过静电纺丝法成纤.对于添加了0.225mol/L的混合金属离子的pH为6.0的再生丝素蛋白水溶液而言,丝素溶液的静电纺丝可纺浓度在27%～35%之间,随着丝素浓度的增加,所制纤维的平均直径增大,直径分布变宽.通过拉曼光谱、X衍射、DSC对再生丝素蛋白纤维的结构进行了表征,发现再生丝素蛋白纤维中已含有少量的Silk Ⅱ结构,主要是无定形结构.     

仿生制备的再生丝素蛋白水溶液的静电纺丝(Ⅱ)——pH值的影响

制备了与蚕体内相近浓度的再生丝素蛋白水溶液并模仿其腺体内不同部位的pH值(从6.9～5.2)对溶液进行了调节,研究了不同pH下丝素蛋白水溶液的流变性能,并对溶液进行了静电纺丝的尝试.研究结果表明,随着pH值的下降,体系的表观粘度增大,对剪切的敏感性提高;利用静电纺丝技术成功获得了平均直径在700nm的丝纤维,通过拉曼光谱、X衍射、DSC对再生丝素蛋白纤维的结构进行了表征,发现再生丝素蛋白纤维主要是无规卷曲或silk Ⅰ结构,pH值的降低,有利于静电纺丝纤维从无规卷曲或silk Ⅰ结构向silk Ⅱ结构转变.     

MWNTs/丝素/聚酰胺共混静电纺纳米纤维毡的结构和性能

静电纺再生丝素纤雏具有在水中易溶胀、结构稳定性和力学性能差等缺陷.在前期研究聚酰胺6/66对静电纺丝素纤维的结构和性能改进效果的基础上,以多壁碳纳米管(MWNTs)增强静电纺丝素/聚酰胺6/66复合纳米纤维.研究发现,随着MWNTs含量的增加复合纤维毡的颜色由白色变成黑色,纤维直径逐渐减小,并且都在90nm以下.MWNTs的加入,还有效地提高了纤维的结晶度、热稳定性以及纤维毡的拉伸力学性能.     

再生丝素/丝胶蛋白水溶液的同轴干法纺丝

模仿蚕丝的成分、结构和成丝方法,通过同轴干法纺丝初步制备了以添加有金属钙离子（Ca2＋）并调节了pH值的再生丝素蛋白（RSF）为芯层、丝胶蛋白（SS）为皮层的RSF/SS纤维。采用荧光显微镜、扫描电镜、拉曼光谱和材料试验机研究了所得纤维的微观形貌、二级结构和力学性能,并与纯RSF纤维和蚕丝进行了对比。研究结果表明同轴干法纺RSF/SS纤维具有清晰的皮-芯层结构,直径较粗且表面略有皱痕;与纯RSF纤维相比,该初生纤维具有更多的β-折叠构象,力学性能也相对较好,但与天然蚕丝相比尚有较大差距。     

静电纺丝制备聚吲哚导电纳米纤维及其性能表征

采用化学氧化还原法合成了聚吲哚,利用静电纺丝技术制备了聚吲哚导电纳米纤维,并通过正交实验优化工艺参数为纺丝液浓度2%,挤出速率1 m L/h,纺丝电压20 k V,接收距离18 cm,最终制得直径为216 nm的聚吲哚导电纳米纤维。利用扫描电镜、红外光谱、X射线衍射、差示扫描量热恩熙及电导率测试对聚吲哚纳米纤维的结构和性能进行了表征,结果表明,静电纺丝过程中聚吲哚的分子链结构并没有发生明显变化;静电纺聚吲哚纳米纤维的结晶更完善、电导率提升了近120%。静电纺丝后聚吲哚的玻璃化转变温度和熔融温度变化不大,分别在130℃和240℃附近,但热降解温度从465℃下降至420℃。     

丝胶组分和高湿后处理对静电纺丝素纤维结构与性能的影响

利用静电纺丝法制备了再生丝素和再生丝素/丝胶蛋白纤维,并对所得纤维进行了高湿后处理。采用扫描电镜分析了丝胶蛋白和高湿后处理对静电纺再生丝素蛋白纤维形貌的影响,采用拉曼光谱、X射线衍射和热失重分析研究了所得纤维微细结构及热性能。研究结果表明,添加丝胶蛋白有利于降低静电纺再生丝素蛋白纤维的直径及其分布,而高湿后处理对纤维的形貌没有明显影响;添加丝胶蛋白和/或高湿后处理有利于促进丝素发生向β-折叠构象的转变,并使纤维的结晶结构得到改善,从而进一步提高纤维的热稳定性。     

Electrospun ultra-fine silk fibroin fibers from aqueous solutions

By using electrospinning technique, beaded, cylinder shaped and ribbon like ultra-fine silk fibroin (SF) fibers were obtained from its concentrated aqueous solution under different processing conditions. These fibers had an average diameter of 700 nm and were characterized by scanning electron microscopy (SEM), Wide-angle X-ray diffraction (WAXD) and Raman spectroscopy. It was found that the morphology and the secondary structure of the as-spun SF fibers were strongly influenced by the solution concentration, as well as the processing voltage. By adjusting these technological parameters, β-sheet conformation and silk II crystal structure of the SF fibers can be formed without any post-treatment.     

Fabrication of novel biofibers by coating silk fibroin with chitosan impregnated with silver nanoparticles

Nanoparticle based agents often applied as coatings on biomaterials have shown promise in delivering the improved sterility against variety of microbes. In the present study, silk fibers (SF) were coated with chitosan impregnated with silver nanoparticles (Ag–C–SF). These Ag–C–SF fibers were characterized using scanning electron microscopy (SEM) with energy dispersive X-ray analysis, atomic force microscopy (AFM), Infra Red spectroscopy, Thermogravimetric Analysis and Microbiological assay techniques. AFM studies have confirmed the nano sized silver particles in chitosan solution; SEM pictures have exhibited the coating of chitosan along with silver nanoparticles on the silk fibroin. The modified fibers have also shown anti-microbial activity and improved thermal stability. The Ag–C–SF fibers may be explored as wound dressing and tendon reconstruction material in future.     

Analysis of structure and properties of biodegradable regenerated silk fibroin fibers

In this paper, the molecular weight change of native silk fibroin fibers when they are dissolved in neutral salt solution, and the relationships of structural change of the regenerated SF fibers with their mechanical properties and degradability have been studied. The results shows that the mechanical properties of regenerated SF fibers are lower than those of native SF fibers, but the biodegradability is raised.     

再生丝素/丝胶共混蛋白水溶液的静电纺丝

采用静电纺丝方法制备了再生丝素/丝胶共混纤维,分析了共混配比对再生丝素/丝胶水溶液流变性能和静电纺可纺性的影响,通过扫描电镜、拉曼光谱和DSC等手段研究了所得纤维的形态和微细结构及其力学性能。研究结果表明:随着溶液中丝胶含量的增加,体系的表观粘度增大,静电纺纤维的直径减小且直径分布变窄;并且丝胶的存在有利于丝素蛋白从无规卷曲或α-螺旋结构向β-折叠结构转变,由此可提高静电纺纤维的力学性能。     

以LiBr/C2H5OH/H2O为溶剂的PVA/SF共混体系的相容性

采用LiBr/C2H5OH混合溶剂制备丝素(SF)溶液,与聚乙烯醇(PVA)水溶液进行溶液共混后得到PVA/SF共混膜,采用扫描电镜,差示扫描量热分析,红外光谱,X射线衍射等方法对共混膜进行了形态和结构表征。研究表明,相对于将PVA水溶液与SF水溶液共混得到的共混体系,此方法制备的体系中两组分的相容性得到了一定程度的提高。在SF含量较小的情况下,共混体系中几乎观察不到两相结构的存在。证明在PVA/SF体系中,SF的溶剂选择及SF的含量影响两种组分的相容性。     

纳米羟基磷灰石/丝素蛋白/聚己内酯复合超细纤维的制备及表征

通过静电纺丝法制备出纳米羟基磷灰石/丝素蛋白/聚己内酯复合超细纤维,利用扫描电镜、红外光谱仪、X射线衍射仪对纳米羟基磷灰石/丝素蛋白/聚己内酯复合超细纤维形貌和结构进行表征,并进行了拉伸测试。结果表明,随着超细纤维中羟基磷灰石含量的增加,纤维的直径逐渐降低,纤维中聚己内酯的结晶逐渐变差。相比于丝素蛋白/聚己内酯超细纤维,含有质量比为30%羟基磷灰石的复合超细纤维仍具有较好的力学性能。体外小鼠成纤维细胞(L929)培养表明,纳米羟基磷灰石/丝素蛋白/聚己内酯复合超细纤维对细胞没有毒性。     

Graphitization behavior of iodine-treated <Emphasis Type="Italic">Bombyx mori</Emphasis> silk fibroin fiber

In order to investigate the graphitization behavior of Bombyx mori silk fibroin (SF) fibers, structural inspection of carbonized SF fibers treated with iodine vapor was studied at different temperatures, from 800 to 1400 °C. Wide angle X-ray diffraction measurement suggested that both untreated and iodinated SF fibers exhibited amorphous structure carbonized to 1200 °C. After carbonization at 1400 °C for 12 h, a graphite-like structure was obtained. Raman spectroscopy and transmission electron microscopic observation showed that the graphite layers of SF fibers became more ordered after iodine treatment. The carbon yield obtained at higher temperature (1400 °C) after iodine treatment was higher, ca. 28 wt%, than that of untreated SF.     

Nano-scaled hydroxyapatite/polymer composite I. Coating of sintered hydroxyapatite particles on poly(γ-methacryloxypropyl trimethoxysilane)-grafted silk fibroin fibers through chemical bonding

The inorganic-organic composite consisting of nano-scaled hydroxyapatite (HAp) and silk fibroin (SF) fibers was prepared through covalent linkage to develop a novel biomaterial for a soft-tissue-compatible material. The preparation of the composite was conducted through the three-step procedure consisting of chemical modification using 2-methacryloxyethyl isocyanate (MOI) monomer to introduce vinyl groups on SF, poly(gamma-methacryloxypropyl trimethoxysilane) (MPTS) graft-polymerization on SF, and coupling process between the surface of polyMPTS-grafted SF and HAp nano-particles. The amount of the graft-polymerization of polyMPTS through vinyl groups was well controlled by the reaction time. The nano-crystals were subsequently coated on the grafted fibers by heating at 120 degrees C for 2 h in a vacuum. The crystalline structure of the SF substrate did not change in the procedure. In the SEM observation of the composite surface, it was found that the bonded nano-crystals were separated and partially aggregated with several crystals attached on the SF fiber surface. The HAp particles adhered more strongly on the SF surface with separation or aggregation of several crystals than on the surface of the original SF after ultrasonic treatment.     

丝素/海藻酸钠膜韧性的优化及膜释药机理分析

首先在丝素(SF)溶液中添加既定浓度的海藻酸钠(SA)溶液和一定体积的75%甘油、50%戊二醛以及模型药物罗丹明B(4g/L),将均匀混合液以浇铸方法制备丝素/海藻酸钠(SF/SA)膜模型药物缓释敷料;然后利用响应曲面法筛选最佳韧性(以断裂伸长率表示)SF/SA膜的制备参数;最后对优化膜的韧性和药物释放动力学模型进行检验与分析。实验得出,在浓度为2.5%的丝素溶液中,添加等体积0.96%浓度的海藻酸钠溶液,且甘油和戊二醛添加量分别为膜液总体积1.41%和4.47%时达到最优制备条件,此时膜的断裂伸长率为228.36%。检验结果显示相对对照组,优化组的断裂伸长率扩大了18.14倍;根据回归方程计算得出影响断裂伸长率的主效因素是甘油,且其与戊二醛具有显著协同作用。另外,根据优化组的释药结果分析表明:该体系具有药物缓释功效,释药动力学归属于Fickan模型。以上结果有利于丝素/海藻酸钠膜舒适型药物缓释敷料的制备,可为该生物材料的应用研究提供参考。