后处理对静电纺丝素纤维膜性能的影响

静电纺丝素纤维膜在载药、组织工程及多种电池的研究中具有广泛的应用.静电纺丝素纤维膜在制备过程中,需要后处理以保持纤维的形状及提升纤维膜的性能.本研究以乙醇和甘油对静电纺丝素纤维膜进行后处理,并通过SEM、FTIR、XRD、TGA等表征手段系统研究了不同后处理条件对静电纺丝素纤维膜的结构及性能的影响,并分析及探讨了其影响机制.结果表明:仅用75％(体积分数)乙醇后处理可使丝素蛋白分子β折叠含量增大,纤维膜断裂强度显著增强;仅用甘油后处理可使丝素蛋白分子链无规卷曲度提高,纤维膜的断裂伸长率显著提高,亲水性大大增强;而用75％乙醇结合不同浓度的甘油对静电纺丝素纤维膜进行后处理可调控其力学性能,使其更能满足在不同领域的应用需求.     

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.     

载药电纺丝素蛋白纤维毡的结晶含量对其药物释放的影响

以水溶液体系的再生丝素蛋白为原料,利用静电纺丝技术制备了载罗丹明B的丝素蛋白纤维毡。利用甲醇水溶液对其进行后处理,考察了不同处理时间下丝素蛋白的结晶含量对药物释放的影响。通过水溶性质量损失率、接触角、扫描电镜、傅里叶红外光谱、X射线衍射光谱及紫外光谱对处理前后的丝素蛋白纤维毡的表面形貌和结构以及药物释放行为进行了表征。结果表明,随着甲醇水溶液处理时间的延长,电纺丝纤维的质量损失率减小,亲水性减弱,丝纤维中的Silk II结晶(由β-折叠结构组成)含量增加,药物释放速率也增加。即通过控制处理时间,可以控制丝纤维中Silk II结晶的含量,从而控制药物的释放速率。     

Genipin交联丝素蛋白纳米纤维膜的制备与性能

利用Genipin对再生丝素蛋白进行交联改性,并通过静电纺丝法制备交联的丝素蛋白纳米纤维膜.利用场发射扫描电镜、红外光谱仪、X射线衍射仪、热重分析仪以及拉力机等对其结构与性能进行表征与测试.结果表明,随着交联剂Genipin质量比的增加,交联度增加,静电纺丝素蛋白纳米纤维平均直径增大,标准偏差增大;Genipin交联对丝素蛋白纳米纤维结晶结构影响不大,但热性能提高;常温条件下,随着Genipin质量比从2％提高至15％,丝素蛋白纳米纤维膜的力学性能逐渐增强,质量比为10％时,其力学性能较好,拉伸强度和断裂应变分别为19.6 MPa和5.9％;随着试验温度从40℃升高到200℃,丝素蛋白纳米纤维膜的拉伸强度和断裂应变先增大然后减小,当试验温度为80℃时,其力学性能较好,拉伸强度和断裂应变分别为41.6 MPa和8.6％.     

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.     

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.     

Genipin交联丝素蛋白纳米纤维膜的制备与性能

利用Genipin对再生丝素蛋白进行交联改性, 并通过静电纺丝法制备交联的丝素蛋白纳米纤维膜。利用场发射扫描电镜、 红外光谱仪、 X射线衍射仪、 热重分析仪以及拉力机等对其结构与性能进行表征与测试。结果表明, 随着交联剂Genipin质量比的增加, 交联度增加, 静电纺丝素蛋白纳米纤维平均直径增大, 标准偏差增大;Genipin交联对丝素蛋白纳米纤维结晶结构影响不大, 但热性能提高;常温条件下, 随着Genipin质量比从2%提高至15%, 丝素蛋白纳米纤维膜的力学性能逐渐增强, 质量比为10%时, 其力学性能较好, 拉伸强度和断裂应变分别为19.6 MPa和5.9%;随着试验温度从40 ℃升高到200 ℃, 丝素蛋白纳米纤维膜的拉伸强度和断裂应变先增大然后减小, 当试验温度为80 ℃时, 其力学性能较好, 拉伸强度和断裂应变分别为41.6 MPa和8.6%。     

再生丝素/聚乙烯醇共混纳米纤维的制备及表征

以三氟乙酸、二氯甲烷和水为溶剂,采用静电纺丝的方法制备再生丝素/聚乙烯醇共混纳米纤维。分析了共混配比对相容性及静电纺丝的影响,采用扫描电镜、X射线衍射仪、红外光谱仪等对所得纤维的形态与结构进行了表征,测试了纳米纤维的力学性能,结果表明:丝素分子和聚乙烯醇分子间发生了某种程度的相互作用,相容性得到改善,添加聚乙烯醇的丝素纳米纤维的力学性能有明显改善。     

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。     

再生丝素蛋白水溶液静电纺丝性能的研究

运用静电纺丝方法,从再生蚕丝素蛋白水溶液中制得了念珠状的、圆形的或扁平状的超细再生丝,纤维的直径在100～900nm之间,平均为700nm.溶液浓度和电压强度对静电纺丝性能的影响很大,当纺丝液浓度为28%（质量分数）,电压为20kV,喷射距离为 11cm时,可制得具有光滑表面的圆形再生丝.大角X衍射（WAXD）测试结果认为,静电纺再生丝中含有α螺旋和β-折叠结构,但其结构既不同于无定型丝素膜,也不同于天然蚕丝纤维,介于二者之间.     

Conformation transition of Bombyx mori silk protein monitored by time-dependent fourier transform infrared (FT-IR) spectroscopy: effect of organic solvent

The conformation transition from random coil and/or helix to β-sheet of silk protein is the most important step in the formation of silk fiber in nature as well as by artificial spinning. Time-dependent Fourier transform infrared (FT-IR) spectroscopy was used in this research to monitor such a conformation transition process induced by the organic solvents methanol, ethanol, propanol, isopropanol, and acetone. The kinetics of β-sheet formation of regenerated Bombyx mori silk fibroin in these organic solvents was obtained by the Δabsorbance-time curve from the time-dependent difference infrared spectra. The results showed that the conformation transition rate of silk fibroin was methanol > ethanol > acetone > propanol > isopropanol, which is in accordance with the polarity of these organic solvents. In connection with the mechanical properties and morphologies of regenerated silk fibers using these organic solvents as coagulation bath reported in the literature, we may conclude that the conformation transition rate of silk protein in the organic solvent is very important in wet-spinning to produce high-performance regenerated silk fibers.     

丝素在离子液体中的溶解及再生丝素纤维的结构

以离子液体1-丁基-3-甲基咪唑氯盐（[BMIM]Cl）为溶剂,研究了丝素蛋白在[BMIM]Cl中的溶解情况,结果表明,温度对丝素在[BMIM]Cl中的溶解有较大影响,当温度〈90℃时,即使延长溶解时间,丝素也难以溶解,而当温度≥90℃时,随着温度升高,溶解速率明显加快。考虑到高温会使丝素降解,因此,选择100℃为丝素...     

Preparation and characterization of regenerated fiber from the aqueous solution of Bombyx mori cocoon silk fibroin

The regenerated silk fibers with high strength and high biodegradability were prepared from the aqueous solution of Bombyx mori silk fibroin from cocoons with wet spinning method. Although the tensile strength of the regenerated silk fibroin fiber, 210 MPa is still half of the strength of native silk fiber, the diameter of the fiber is about 100 μm which is suitable for monofilament of suture together with high biodegradability. The high concentration (30%, w/v) of the aqueous solution of the silk fibroin which corresponds to the high concentration in the middle silkgland of silkworm was obtained. This was performed by adjusting the pH of the aqueous solution to 10.4 which corresponds to pK_a value of the OH group of Tyr residues in the silk fibroin. The mixed solvent, methanol/acetic acid (7:3 in volume ratio) was used as coagulant solvent for preparing the regenerated fiber. The structural change of silk fibroin fiber by stretching was monitored with both ¹³C solid state NMR and X-ray diffraction methods, indicating that the high strength of the fiber is related with the long-range orientation of the silk fibroin chain with β-sheet structure.     

甲醇处理对再生丝素蛋白干法纺丝纤维结构及性能的影响

采用甲醉水溶液对初生的再生丝素蛋白干法纺丝纤维进行了后处理.研究表明,甲醉处理对再生丝的表面形态、结晶结构及机械性能有影响.甲醇处理前,初生丝蛋白纤维透明而有光泽;甲醇处理后,丝纤维呈现白色,光泽度下降,同时沿纤维轴方向出现了细小的条纹,并可观察到明显的双折射现象.甲醉处理还可使初生丝蛋白纤维中存在的无规卷曲或Silk...     

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.     

再生桑蚕丝素/柞蚕丝素蛋白静电纺无纺网结构的研究

通过SEM、X射线衍射、FT-IR等方法分析研究了80%桑蚕丝素/20%柞蚕丝素共混静电纺纤维无纺网的形态和聚集态结构。结果表明,本实验条件下,无纺网为微米级纤维直径,桑蚕丝素和柞蚕丝素蛋白在结晶区内也相容。     

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.     

Spider silk as an active scaffold in the assembly of gold nanoparticles and application of the gold-silk bioconjugate in vapor sensing

Spider silk is being viewed with interest by materials scientists due to its excellent resilience and mechanical properties. In this paper we show that spider silk is an excellent scaffold for the one-step synthesis and assembly of gold nanoparticles. Formation of a gold nanoparticle-spider-silk bioconjugate material is accomplished by simple reaction of the fibers with aqueous chloroauric acid. The gold nanoparticles thus formed are strongly bound to the spider-silk fiber surface enabling study of the electrical properties of the nanobioconjugate. Using the well-known contraction/expansion behavior of the fibers in solvents of varying polarity, we show that exposure of the gold nanoparticle-spider silk bioconjugate to vapors of methanol and chloroform leads to changes in electrical transport through the nanoparticles and thus, the possibility of developing a vapor sensor. The bioconjugate shows excellent response time and cycling efficiency to methanol vapors. The activation energy of electron transport from one gold nanoparticle to another in the nanobiocojugate was determined from temperature-dependent electron-transport measurements to be approximately 1.7 eV.     

Fabrication and characterization of fibroin solution and nanoparticle from silk fibers of Bombyx mori

The present investigation aims to study the effect of degumming time on the structural property of silk fiber obtained by silk cocoons of Bombyx mori, followed by preparation of the regenerated silk fibroin (RSF) solution which can be subsequently molded into silk nanoparticles. Silk fibers degummed with different media at different time intervals were investigated for the degumming loss and were characterized using Ffourier transform infrared (FTIR), differential scanning calorimetry (DSC), x-ray diffraction (XRD), and scanning electron microscopy (SEM). Maximum degumming was observed when the fibers were treated with sodium carbonate for 60 min. SEM and atomic force microscopy (AFM) images of RSF solution showed aggregation of silk globules resulting in formation of solvated macrochains and giving it an appearance of island-like morphology. Blank silk nanoparticles prepared from the RSF solution showed a smooth and spherical surface devoid of any adhesion using SEM, AFM, and transmission electron microscopy (TEM). The prepared silk nanoparticles may further be explored for loading drug entities and targeting.