静电纺丝复合纳米纤维研究进展

静电纺丝是一种利用聚合物溶液或熔体在强电场中进行喷射纺丝的加工技术,是获得纳米尺寸纤维的有效方法之一。然而单一组分的纳米纤维已经难以满足应用的需求,而采用两种或两种以上的聚合物(或聚合物/填料颗粒)进行静电纺丝得到的复合纳米纤维逐渐受到了人们的关注。文中总结了由静电纺丝技术制备的复合纳米纤维及其性能等方面的研究进展。主要包括复合物/碳复合纳米纤维、聚合物/金属复合纳米纤维、聚合物/粘土复合纳米纤维、共混物复合纳米纤维、装饰型复合纳米纤维等。     

双层蛛丝蛋白血管支架的体外降解研究

血管支架的制备成为治疗心血管疾病的必需条件。应用静电纺丝技术制备了(pNSR16/PCL/CS)/(pNSR16/PCL/Gt)双层血管支架,并研究其在磷酸盐缓冲液(pH值=7.4)和多酶降解液中浸泡不同时间的体外降解情况。于2、4、8、12周分别取材,测试失重率、吸水率、降解液的pH值、力学性能和分子量的变化,并进行扫描电镜观察。结果表明,(pNSR16/PCL/CS)/(pNSR16/PCL/Gt)双层血管支架的初始抗弯强度和初始分子量大于(PCL/CS)/(PCL/Gt)支架,并且前者的降解速度、分子量和失重率减少速度快于后者,pNSR16的添加促进了血管支架的降解。在降解过程中,浸泡液pH值呈弱酸性和中性,前期迅速降低并在后期呈现稳定的趋势。支架在酶解液中的降解速度快于在水解液中。     

静电纺丝工艺对PVP/TEOS/硝酸盐复合纳米纤维成纤性状的影响

采用静电纺丝技术制备了PVP/[Sr(NO3)2+Mg(NO3)2+TEOS+Eu(NO3)2+Dy(NO3)2]复合纳米纤维,研究了不同静电纺丝工艺参数对其成纤性状的影响。结果表明:纤维的直径均随着电压、无机盐和PVP含量的增加呈现先减小后增大的趋势;随着纺丝液中无机盐含量的增加,纺丝液的黏度、表面张力和电导率均逐渐增大;随着PVP含量的增加,纺丝液的黏度、表面张力逐渐增大、电导率先减小后增大。SEM分析表明,当纺丝电压在13~15kV,纺丝液中无机盐含量为5%~6%,PVP含量为15%时,易获得形貌较好的复合纳米纤维。     

纳米羟基磷灰石/玉米醇溶蛋白复合超细纤维的制备与性能

利用静电纺丝制备出纳米羟基磷灰石(nHA)/玉米醇溶蛋白(zein)复合超细纤维。通过场发射扫描电镜、透射电镜观察了纳米羟基磷灰石/玉米醇溶蛋白复合超细纤维的形貌;利用红外光谱仪、X射线衍射仪对纳米羟基磷灰石/玉米醇溶蛋白复合超细纤维结构和性能进行表征,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,纤维的直径先减小后增大,纤维中纳米羟基磷灰石的结晶逐渐变好。相比于玉米醇溶蛋白超细纤维,含有质量分数为25%羟基磷灰石的复合超细纤维仍具有较好的力学性能。     

PVDF/SiO_2原位复合纳米纤维膜的制备及性能研究

采用原位复合溶胶一凝胶法配制复合纺丝液,通过高压静电纺丝制备出PVDF／SiO2复合纳米纤维膜。采用FTIR分析了PVDF与Si02分子间的相互作用,并通过TEM表征了纳米二氧化硅的具体分散状态。研究了纳米si02的加入对膜的热性能、结晶行为及力学性能的影响。结果表明,原位复合溶胶一凝胶法使纳米Si02在PVDF中具有...     

静电纺丝制备二氧化硅纳米纤维的形貌控制

使用溶胶-凝胶和静电纺丝相结合的方式制备二氧化硅纳米纤维,采用PVP/乙醇溶液作为实验用剂,通过调整结构导向剂P123的量来探究其对所得多孔纳米纤维形貌的影响。利用电子扫描显微镜(SEM)、电子透射显微镜(TEM)以及氮气吸附-脱附对得到的多孔纤维进行表征。结果显示,结构导向剂P123的使用量是影响二氧化硅纳米纤维的比表面积的主要因素,但是对孔径分布没有影响。     

静电纺丝制备二氧化硅纳米纤维的形貌控制

使用溶胶一凝胶和静电纺丝相结合的方式制备二氧化硅纳米纤维,采用PVP／乙醇溶液作为实验用剂,通过调整结构导向剂P123的量来探究其对所得多孔纳米纤维形貌的影响。利用电子扫描显微镜（SEM）、电子透射显微镜（TEM）以及氮气吸附一脱附对得到的多孔纤维进行表征。结果显示,结构导向剂P123的使用量是影响二氧化硅纳米纤维的比...     

复合纳米纤维静电纺丝法的制备及其磁性

以聚乙烯吡咯烷酮（PVP）和金属盐为原料,利用静电纺丝法成功制备出了摩尔比为1：1的SrTiO3-SrFe12O19磁电复合纳米纤维。并通过FT-IR,XRD,SEM和VSM等技术对纤维前驱体及其产物的结构、热处理产物的物相、形貌及磁性能进行了表征。结果表明,样品经900℃焙烧2h后,即可得到纯的SrTiO3和SrFe...     

聚乳酸/茶多酚复合纳米纤维膜制备及力学性能研究

采用静电纺丝技术,分别制备了聚乳酸(PLA)与茶多酚(TP)质量混比为100/0、90/10、80/20、70/30、60/40、50/50、40/60、30/70和20/80的复合纳米纤维膜.分别借助扫描电子显微镜(SEM)和KDⅡ-0.05微机控制电子万能试验机观察薄膜表面形貌及测试力学性能.SEM图分析结果表明:当PLA与TP的质量混比从100/0变化到50/50时,均能纺出较连续、光滑的纤维.随着纺丝液中PLA含量的减少,TP含量的增加,所纺纤维直径逐渐变小.超出这个范围,纤维断裂现象加剧,甚至出现纳米级颗粒团聚的现象.复合纳米纤维膜的拉伸强度逐渐减小,断裂伸长率先增加后减小.     

重组蛛丝蛋白pNSR-16/聚乙烯醇复合材料的研究

研究基因重组蛛丝蛋白pNSR-16与聚乙烯醇(PVA)共混复合材料.结果表明高分子量的PVA-124对蛛丝蛋白的改性效果较好;IR分析表明PVA-124分子能促进pNSR-16分子构象由无规卷曲向β-折叠转化;SEM观察表明pNSR-16与PVA-124相容性好;体外细胞培养初步证明了复合支架材料具有生物相容性.     

Correlation between protein secondary structure and mechanical performance for the ultra-tough dragline silk of Darwin's bark spider

The spider major ampullate (MA) silk exhibits high tensile strength and extensibility and is typically a blend of MaSp1 and MaSp2 proteins with the latter comprising glycine–proline–glycine–glycine-X repeating motifs that promote extensibility and supercontraction. The MA silk from Darwin''s bark spider (Caerostris darwini) is estimated to be two to three times tougher than the MA silk from other spider species. Previous research suggests that a unique MaSp4 protein incorporates proline into a novel glycine–proline–glycine–proline motif and may explain C. darwini MA silk''s extraordinary toughness. However, no direct correlation has been made between the silk''s molecular structure and its mechanical properties for C. darwini. Here, we correlate the relative protein secondary structure composition of MA silk from C. darwini and four other spider species with mechanical properties before and after supercontraction to understand the effect of the additional MaSp4 protein. Our results demonstrate that C. darwini MA silk possesses a unique protein composition with a lower ratio of helices (31%) and β-sheets (20%) than other species. Before supercontraction, toughness, modulus and tensile strength correlate with percentages of β-sheets, unordered or random coiled regions and β-turns. However, after supercontraction, only modulus and strain at break correlate with percentages of β-sheets and β-turns. Our study highlights that additional information including crystal size and crystal and chain orientation is necessary to build a complete structure–property correlation model.     

Nanostructure and molecular mechanics of spider dragline silk protein assemblies

Spider silk is a self-assembling biopolymer that outperforms most known materials in terms of its mechanical performance, despite its underlying weak chemical bonding based on H-bonds. While experimental studies have shown that the molecular structure of silk proteins has a direct influence on the stiffness, toughness and failure strength of silk, no molecular-level analysis of the nanostructure and associated mechanical properties of silk assemblies have been reported. Here, we report atomic-level structures of MaSp1 and MaSp2 proteins from the Nephila clavipes spider dragline silk sequence, obtained using replica exchange molecular dynamics, and subject these structures to mechanical loading for a detailed nanomechanical analysis. The structural analysis reveals that poly-alanine regions in silk predominantly form distinct and orderly beta-sheet crystal domains, while disorderly regions are formed by glycine-rich repeats that consist of 3₁-helix type structures and beta-turns. Our structural predictions are validated against experimental data based on dihedral angle pair calculations presented in Ramachandran plots, alpha-carbon atomic distances, as well as secondary structure content. Mechanical shearing simulations on selected structures illustrate that the nanoscale behaviour of silk protein assemblies is controlled by the distinctly different secondary structure content and hydrogen bonding in the crystalline and semi-amorphous regions. Both structural and mechanical characterization results show excellent agreement with available experimental evidence. Our findings set the stage for extensive atomistic investigations of silk, which may contribute towards an improved understanding of the source of the strength and toughness of this biological superfibre.     

正交试验优化复合纳滤膜复合条件

采用聚砜基膜,以哌嗪水溶液与均苯三甲酰氯正己烷有机溶液发生界面聚合反应,在聚砜基膜上形成一超薄脱盐层,从而制备聚哌嗪酰胺复合纳滤膜．制备过程中影响复合纳滤膜性能的因素是多方面的．着重讨论了水相浓度、有机相浓度、有机相处理时间的影响．采用正交试验法对制备条件进行优化,制得性能较佳的复合纳滤膜．     

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。     

Physical characterization of functionalized spider silk: electronic and sensing properties

This work explores functional, fundamental and applied aspects of naturally harvested spider silk fibers. Natural silk is a protein polymer where different amino acids control the physical properties of fibroin bundles, producing, for example, combinations of β-sheet (crystalline) and amorphous (helical) structural regions. This complexity presents opportunities for functional modification to obtain new types of material properties. Electrical conductivity is the starting point of this investigation, where the insulating nature of neat silk under ambient conditions is described first. Modification of the conductivity by humidity, exposure to polar solvents, iodine doping, pyrolization and deposition of a thin metallic film are explored next. The conductivity increases exponentially with relative humidity and/or solvent, whereas only an incremental increase occurs after iodine doping. In contrast, iodine doping, optimal at 70 °C, has a strong effect on the morphology of silk bundles (increasing their size), on the process of pyrolization (suppressing mass loss rates) and on the resulting carbonized fiber structure (that becomes more robust against bending and strain). The effects of iodine doping and other functional parameters (vacuum and thin film coating) motivated an investigation with magic angle spinning nuclear magnetic resonance (MAS-NMR) to monitor doping-induced changes in the amino acid-protein backbone signature. MAS-NMR revealed a moderate effect of iodine on the helical and β-sheet structures, and a lesser effect of gold sputtering. The effects of iodine doping were further probed by Fourier transform infrared (FTIR) spectroscopy, revealing a partial transformation of β-sheet-to-amorphous constituency. A model is proposed, based on the findings from the MAS-NMR and FTIR, which involves iodine-induced changes in the silk fibroin bundle environment that can account for the altered physical properties. Finally, proof-of-concept applications of functionalized spider silk are presented for thermoelectric (Seebeck) effects and incandescence in iodine-doped pyrolized silk fibers, and metallic conductivity and flexibility of micron-sized gold-sputtered silk fibers. In the latter case, we demonstrate the application of gold-sputtered neat spider silk to make four-terminal, flexible, ohmic contacts to organic superconductor samples.     

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%。     

Physical characterization of functionalized spider silk: electronic and sensing properties

Abstract

This work explores functional, fundamental and applied aspects of naturally harvested spider silk fibers. Natural silk is a protein polymer where different amino acids control the physical properties of fibroin bundles, producing, for example, combinations of β-sheet (crystalline) and amorphous (helical) structural regions. This complexity presents opportunities for functional modification to obtain new types of material properties. Electrical conductivity is the starting point of this investigation, where the insulating nature of neat silk under ambient conditions is described first. Modification of the conductivity by humidity, exposure to polar solvents, iodine doping, pyrolization and deposition of a thin metallic film are explored next. The conductivity increases exponentially with relative humidity and/or solvent, whereas only an incremental increase occurs after iodine doping. In contrast, iodine doping, optimal at 70 °C, has a strong effect on the morphology of silk bundles (increasing their size), on the process of pyrolization (suppressing mass loss rates) and on the resulting carbonized fiber structure (that becomes more robust against bending and strain). The effects of iodine doping and other functional parameters (vacuum and thin film coating) motivated an investigation with magic angle spinning nuclear magnetic resonance (MAS-NMR) to monitor doping-induced changes in the amino acid-protein backbone signature. MAS-NMR revealed a moderate effect of iodine on the helical and β-sheet structures, and a lesser effect of gold sputtering. The effects of iodine doping were further probed by Fourier transform infrared (FTIR) spectroscopy, revealing a partial transformation of β-sheet-to-amorphous constituency. A model is proposed, based on the findings from the MAS-NMR and FTIR, which involves iodine-induced changes in the silk fibroin bundle environment that can account for the altered physical properties. Finally, proof-of-concept applications of functionalized spider silk are presented for thermoelectric (Seebeck) effects and incandescence in iodine-doped pyrolized silk fibers, and metallic conductivity and flexibility of micron-sized gold-sputtered silk fibers. In the latter case, we demonstrate the application of gold-sputtered neat spider silk to make four-terminal, flexible, ohmic contacts to organic superconductor samples.     

高水稳定性的ZEIN/CA复合纳米纤维的制备及性能研究

采用静电纺制备了不同质量比的玉米醇溶蛋白(Zein)/醋酸纤维素(CA)复合纳米纤维。傅里叶变换红外光谱(FT-IR)曲线表明样品中两组分各自保持了其原有化学功能基团。利用扫描电镜(SEM)对样品的形貌和直径分布进行了分析。通过差示扫描量热仪(DSC)和热重分析(TGA)研究了样品的热学性能,结果证实了随着CA的加入,样品依然保持较高的热稳定性。表面张力仪(ST)测定结果表明,随着Zein组分的增加,样品的亲水性增加。同时样品具有一定的吸水能力。