Name: molecular entanglement and electrospinnability of biopolymers
Uploaded: 2014-09-03T15:45:00.000+00:00
Duration: 7 min 59 s
Description: Watch this Scientific Journal Video about Molecular Entanglement and Electrospinnability of Biopolymers at JoVE.com

这项工作是由美国农业部国家研究所的粮食和农业，国家竞争力的资助计划，国家研究计划项目71.1 2007年度部分资金作为批准号:2007-35503-18392和美国国立卫生研究院，研究院过敏和传染病，R33AI94514-03。

1，纺丝原液的制备<ol><li>准备进行调查一系列生物聚合物的浓度（0.1％〜30％，W / V），并一定要考虑生物​​聚合物粉末在这些计算中的水分含量。对于每个浓度，称量该生物聚合物（淀粉或支链淀粉）的粉末置于50ml试管中。添加水二甲基亚砜（DMSO）溶液和搅拌棒。 </li><li>将管子放入沸水与磁力搅拌器加热板不断搅拌。 </li><li>经过约1小时，熄火并允许该分散冷却至室温。分散体，然后准备进行流变试验和静电。 </li></ol> 2，稳定剪切流变<ol><li>热身流变仪和设置阶段的温度在20℃。校准探头（用于25毫米锥形）和级（板）之间的间隙。 </li><li>该生物聚合物分散体的负载0.41毫升到台上的中心和降低探头，设置positi在（0.053毫米差距25毫米锥）。确保分散均匀敷于间隙内。 </li><li>用下面的实验参数进行流变学试验:扫描模式:日志，初始速度:100秒-1，最终速率:0.1秒-1，每十点:10，延迟测量结果之前:5秒，测量时间:10秒，而每小节的方向:2（顺时针和逆时针）。 </li><li>分析流变数据来估算适当的分散浓度静电试验。 <ol><li>绘制表观剪切粘度对剪切速率的聚合物浓度的函数。针对每一个流的曲线，近似零剪切粘度，η0，由实际或外推值（ 例如 ，在低浓度时，其中的低剪切速率下的数据是不可靠的）为表观粘度在0.1秒- 1。 </li><li>计算比粘度:ηSP =（η0 - ηS）/ηs，其中ηs是溶剂的粘度。 </li><li>绘制特定粘度随浓度的函数。确定亚浓非缠结和纠​​缠制度。在亚浓非缠结政权从低浓度结尾加上一个小山坡开始，和亚浓纠缠制度具有更大的斜率以下非缠结制度。飞度幂回归模型中的两种制度。功率值是在一个log-log图亚浓非缠结和纠​​缠制度的斜坡（浓度依赖性）。两个拟合线的交点就是纠缠浓度， 居权证。 </li></ol></li></ol> 3，静电参数变化<ol><li>组装静电设置为如图1中所示。装入注射器用的适当组合物的分散性， 例如 ，15％（重量/体积），淀粉或支链淀粉在100％DMSO中，到注射器泵。夹在高压线（POSITIVE）到针。通过浸渍的接地线（负）进入浴缸连接含有纯乙醇对地面的凝固浴中。用一个实验室千斤顶调整注射器针头和凝固浴之间的距离。沉浸金属网在洗澡后，静电收集纤维毡。 </li><li>旋转生物聚合物在下列参数范围:进料速率为0.1至0.4毫升/小时，从5到10厘米纺丝距离，并且电压从0到15千伏。 <ol><li>开始用5厘米的纺丝距离。用于第一进给速率（0.1毫升/小时），缓慢地从0V。讲究斜坡电压上升至挤出在针尖分散体的形状，并注意滴分散体被加速，然后拉长。 </li><li>请注意，在这一个微小的飞机从下拉表面引发，这说明解决方案的electrospinnability的电压。记录在其中的连续喷射启动，如果任何电压。 </li><li>检查全系列为三个paramete的RS和记成功的纺丝条件。收集的纤维时，才会有从前端连续喷射。 </li></ol></li><li>收集了几分钟后，冲洗纤维毡用纯乙醇。将纤维毡为含真空除湿干燥器。 </li><li>重复每个生物聚合物浓度为完整的特征。 </li></ol><img alt="图1" fo:content-width="5in" src="/files/ftp_upload/51933/51933fig1highres.jpg" width="500" /> 电湿式纺丝机的图1示意图。生物聚合物分散体是由注射泵挤出。高压直流电源提供高电压的钝针和地面凝固浴。从针尖的聚合物射流穿过直通道，然后开发了快速搅打路径（又名搅打稳定性）。 4，形态特征<ol><li>剪下一块干燥的纤维毡​​，并使用碳胶带固定其上的SEM​​存根。 </li><li>将样品存根放入扫描电镜仪器获取图像进行分析。 </li></ol>

<ol>
	<li>Greiner, A., Wendorff, J. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Functional+self-assembled+nanofibers+by+electrospinning.">Functional self-assembled nanofibers by electrospinning.</a> Self-aseembled nanomaterials. 1, 107-171 (2008).</li><li>Ramakrishna, S., Fujihara, K., Teo, W. E., Lim, T. C., Ma, Z. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> An Introduction to Electrospinning and Nanofibers. , (2005).</li><li>Klossner, R. R., Queen, H. A., Coughlin, A. J., Krause, W. 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E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Solution+rheological+behavior+and+electrospinning+of+cationic+polyelectrolytes.">Solution rheological behavior and electrospinning of cationic polyelectrolytes.</a> Macromolecules. 39 (2), 575-583 (2006).</li><li>Kong, L., Ziegler, G. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fabrication+of+pure+starch+fibers+by+electrospinning.">Fabrication of pure starch fibers by electrospinning.</a> Food Hydrocolloids. 36, 20-25 (2014).</li><li>Singh, R. S., Saini, G. K., Kennedy, J. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Pullulan:+microbial+sources,+production+and+applications.">Pullulan: microbial sources, production and applications.</a> Carbohydrate Polymers. 73 (4), 515-531 (2008).</li><li>Leathers, T. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Biotechnological+production+and+applications+of+pullulan.">Biotechnological production and applications of pullulan.</a> Applied Microbiology and Biotechnology. 62 (5), 468-473 (2003).</li><li>Karim, M. R., Lee, H. W., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Preparation+and+characterization+of+electrospun+pullulan/montmorillonite+nanofiber+mats+in+aqueous+solution.">Preparation and characterization of electrospun pullulan/montmorillonite nanofiber mats in aqueous solution.</a> Carbohydrate Polymers. 78 (2), 336-342 (2009).</li><li>Stijnman, A. C., Bodnar, I., Hans Tromp, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Electrospinning+of+food-grade+polysaccharides.">Electrospinning of food-grade polysaccharides.</a> Food Hydrocolloids. 25 (5), 1393-1398 (2011).</li><li>Kong, L., Ziegler, G. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Role+of+molecular+entanglements+in+starch+fiber+formation+by+electrospinning.">Role of molecular entanglements in starch fiber formation by electrospinning.</a> Biomacromolecules. 13 (8), 2247-2253 (2012).</li><li>Kong, L., Ziegler, G. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Rheological+aspects+in+fabricating+pullulan+fibers+by+electro-wet-spinning.">Rheological aspects in fabricating pullulan fibers by electro-wet-spinning.</a> Food Hydrocolloids. 38, 220-226 (2014).</li><li>Han, C. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Fiber Spinning Rheology and Processing of Polymeric Materials: Volume 2: Polymer Processing. , 257-304 (2007).</li><li>Morris, E. R., Cutler, A. N., Ross-Murphy, S. B., Rees, D. A., Price, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Concentration+and+shear+rate+dependence+of+viscosity+in+random+coil+polysaccharide+solutions.">Concentration and shear rate dependence of viscosity in random coil polysaccharide solutions.</a> Carbohydrate Polymers. 1 (1), 5-21 (1981).</li><li>Thompson, C. J., Chase, G. G., Yarin, A. L., Reneker, D. 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作者宣称，他们什么都没有透露。

流变学是研究聚合物，包括常规纤维纺丝和静电13的处理的一个重要工具。从稳态剪 ​​切流变学研究，聚合物的构象和它们在不同溶剂中的相互作用可以得到解决（ 图2和3）。在浓度不够高的生物聚合物分子彼此重叠，它们的浓度依赖性为1.4左右（ 图3），这是与其它聚合物的良溶剂3,4报道值相符。经过生物聚合物分子开始纠缠，具体粘度?...

静电纺丝是一种技术，其能够从各种各样的材料生产连续微纳米级纤维。它已经获得了越来越多的学术和产业的利益1。虽然设置和静电的做法看似简单，预测electrospinnability和控制纤维性能的能力仍然是一个挑战。其原因可能在于这一事实有影响的电纺丝过程2和过程，特别是由光纤行进的路径，是混沌1许多因素。往往是经验的"煮和 - 看"的方法，用于筛选潜在electrospinnable材料。然而，为了更好地控制电纺丝过程和所得纤维的性能，支配electrospinnability所需的机制的一个更完整的理解。一些研究人员已经发现，在纺丝原液的聚合物的分子缠结是一个essentia升前提成功的静电3-5。 流变学是一个强大的工具来探测分子构象和互动的聚合物分散体。例如，McKee 等 。研究了线性的含有氯仿/对苯二甲酸二甲酯（7:3，V / V）的分子构象和支链聚（对苯二甲酸乙二酯 - 共 - 间苯二甲酸乙二醇酯）的共聚物在溶剂中，并确定该聚合物的浓度必须是2-2.5x纠缠浓度为成功的静电4。 有从的，因为它们的生物降解性，生物相容性和可再生相，以对比它们的合成的对应的优点的生物聚合物在纤维目前新的兴趣。然而，从业者面临来自其结构的复杂性，难以热加工和差的机械性能一般产生许多挑战。淀粉，植物组织中发现，是阿蒙G于地球上最丰富和廉价的生物聚合物。纯淀粉纤维的使用电-湿式纺丝装置最近被描述6制成。普鲁兰多糖是由某种细菌细胞外产生的线性多糖。 （1→4）和（1→6） ​​经常交替糖苷键被认为是负责支链淀粉的几个独特的性质，包括优异的纤维/薄膜形成能力7,8。从水分散体的支链淀粉的纤维的静电纺丝已经报道了许多研究者9,10。在我们先前的出版物中，两个生物聚合物，淀粉11和支链淀粉12 electrospinnability，已经讨论过。本报告侧重于展示协议利用流变学原理，这两种生物聚合物的electrospinnability的调查。

<table><tbody><tr><td>Gelose 80 starch</td><td>Ingredion</td><td></td><td>Used as it is</td></tr><tr><td>Pullulan</td><td>Hayashibara Co. Ltd</td><td></td><td>Used as it is</td></tr><tr><td>Dimethyl sulfoxide</td><td>BDH Chemicals</td><td>BDH1115-4LP</td><td></td></tr><tr><td>Ethanol</td><td>VWR International</td><td>89125-172</td><td>200 proof</td></tr><tr><td>Rheometer</td><td>TA Instruments</td><td>ARES&amp;nbsp;</td><td>50 mm cone and plate geometry</td></tr><tr><td>Syringe (10 ml)</td><td>Becton, Dickinson and Company</td><td>309604</td><td>Syringe with Luer-Lok&amp;reg; Tip</td></tr><tr><td>High voltage generator</td><td>Gamma High Voltage Research, Inc.</td><td>ES40P</td><td></td></tr><tr><td>Syringe pump</td><td>Hamilton Company</td><td>81620</td><td></td></tr><tr><td>Environmental scanning electron microscope</td><td>FEI Company</td><td>Quanta 200</td><td>for starch fibers</td></tr><tr><td>Environmental scanning electron microscope</td><td>Phenom-World</td><td>Phenom G2 Pro</td><td>for pullulan fibers</td></tr></tbody></table>

molecular entanglement and electrospinnability of biopolymers

静电是一种令人着迷的技术制造微纳米级纤维的各种材料。为生物聚合物，在纺丝原液的构成聚合物的分子缠结被发现是成功的静电纺丝的基本先决条件。流变学是一个强大的工具来探测生物聚合物的分子构象和互动。在本报告中，我们证明了协议用于利用流变学来评价两种生物聚合物，淀粉和支链淀粉的electrospinnability，从他们的二甲亚砜（DMSO）/水分散液。良好的淀粉和普鲁兰多糖纤维中的亚微米到微米范围内的平均直径分别获得。 Electrospinnability通过肉眼和显微镜观察所形成的纤维进行评价。通过关联分散到其electrospinnability的流变学特性，我们证明了分子构象，分子的缠结和剪切粘度都影响选rospinning。流变不仅是有用的溶剂体系的选择和过程的优化，而且还了解的纤维形成的机制在分子水平上。

得到的生物聚合物的分散体作为生物聚合物的浓度和溶剂的DMSO浓度的函数的流动曲线。两种有代表性的图显示的淀粉（ 图2A）和支链淀粉（ 图2B）的流动曲线，作为其浓度在纯的DMSO溶剂的功能。特定粘度作图对生物聚合物的浓度（ 图3A为淀粉和图3B为支链淀粉）。从这些曲线，缠结浓度得到的半稀释非缠结和亚浓缠结制度的拟合线的截距。 <p...

Watch this Scientific Journal Video about Molecular Entanglement and Electrospinnability of Biopolymers at JoVE.com

Molecular Entanglement and Electrospinnability of Biopolymers

静电是用来从各种材料制作的微纳米级纤维的迷人的技术。在纺丝液的构成聚合物的分子缠结是成功的电纺丝是必不可少的。我们提出了一个协议，利用流变评估两个生物聚合物，淀粉的支链淀粉的electrospinnability。

分子纠缠与生物大分子的Electrospinnability

Electrospinning is a fascinating technique to fabricate micro- to nano-scale fibers from a wide variety of materials. For biopolymers, molecular ...

molecular-entanglement-and-electrospinnability-of-biopolymers

Research

JoVE Journal

Bioengineering

13.7K 次观看.  Pennsylvania State University. 静电是用来从各种材料制作的微纳米级纤维的迷人的技术。在纺丝液的构成聚合物的分子缠结是成功的电纺丝是必不可少的。我们提出了一个协议，利用流变评估两个生物聚合物，淀粉的支链淀粉的electrospinnability。 

视频: Molecular Entanglement and Electrospinnability of Biopolymers

Electrospinning Fundamentals: Optimizing Solution and Apparatus Parameters

Electrospun nanofiber scaffolds have been shown to accelerate the maturation, improve the growth, and direct the migration of cells in vitro. Electrospinning is a process in which a charged polymer jet is collected on a grounded collector; a rapidly rotating collector results in aligned nanofibers while stationary collectors result in randomly oriented fiber mats. The polymer jet is formed when an applied electrostatic charge overcomes the surface tension of the solution. There is a minimum concentration for a given polymer, termed the critical entanglement concentration, below which a stable jet cannot be achieved and no nanofibers will form - although nanoparticles may be achieved (electrospray). A stable jet has two domains, a streaming segment and a whipping segment. While the whipping jet is usually invisible to the naked eye, the streaming segment is often visible under appropriate lighting conditions. Observing the length, thickness, consistency and movement of the stream is useful to predict the alignment and morphology of the nanofibers being formed. A short, non-uniform, inconsistent, and/or oscillating stream is indicative of a variety of problems, including poor fiber alignment, beading, splattering, and curlicue or wavy patterns. The stream can be optimized by adjusting the composition of the solution and the configuration of the electrospinning apparatus, thus optimizing the alignment and morphology of the fibers being produced. In this protocol, we present a procedure for setting up a basic electrospinning apparatus, empirically approximating the critical entanglement concentration of a polymer solution and optimizing the electrospinning process. In addition, we discuss some common problems and troubleshooting techniques.

Electrospinning techniques can create a variety of nanofibrous scaffolds for tissue engineering or other applications. We describe here a procedure to optimize the parameters of the electrospinning solution and apparatus to obtain fibers with the desired morphology and alignment. Common problems and troubleshooting techniques are also presented.

静电基础：优化解决方案和设备参数

Electrospun nanofiber scaffolds have been shown to accelerate the maturation, improve the growth, and direct the migration of cells in vitro. ...

科研

生物工程

Air Filter Devices Including Nonwoven Meshes of Electrospun Recombinant Spider Silk Proteins

Based on the natural sequence of Araneus diadematus Fibroin 4 (ADF4), the recombinant spider silk protein eADF4(C16) has been engineered. This highly repetitive protein has a molecular weight of 48kDa and is soluble in different solvents (hexafluoroisopropanol (HFIP), formic acid and aqueous buffers). eADF4(C16) provides a high potential for various technical applications when processed into morphologies such as films, capsules, particles, hydrogels, coatings, fibers and nonwoven meshes. Due to their chemical stability and controlled morphology, the latter can be used to improve filter materials. In this protocol, we present a procedure to enhance the efficiency of different air filter devices, by deposition of nonwoven meshes of electrospun recombinant spider silk proteins. Electrospinning of eADF4(C16) dissolved in HFIP results in smooth fibers. Variation of the protein concentration (5-25% w/v) results in different fiber diameters (80-1,100 nm) and thus pore sizes of the nonwoven mesh.
Post-treatment of eADF4(C16) electrospun from HFIP is necessary since the protein displays a predominantly &alpha;-helical secondary structure in freshly spun fibers, and therefore the fibers are water soluble. Subsequent treatment with ethanol vapor induces formation of water resistant, stable &beta;-sheet structures, preserving the morphology of the silk fibers and meshes. Secondary structure analysis was performed using Fourier transform infrared spectroscopy (FTIR) and subsequent Fourier self-deconvolution (FSD).
The primary goal was to improve the filter efficiency of existing filter substrates by adding silk nonwoven layers on top. To evaluate the influence of electrospinning duration and thus nonwoven layer thickness on the filter efficiency, we performed air permeability tests in combination with particle deposition measurements. The experiments were carried out according to standard protocols.

Spider silk fibers display extraordinary mechanical properties. Engineered Araneus diadematus Fibroin 4 (eADF4) can be processed into nonwoven meshes using electrospinning. Here, the eADF4 nonwoven meshes are used to improve the performance of air filtering devices.

空气过滤设备，包括非织造网格静电重组蜘蛛丝蛋白

Based on the natural sequence of Araneus diadematus Fibroin 4 (ADF4), the recombinant spider silk protein eADF4(C16) has been engineered. This highly ...

Fabricating Superhydrophobic Polymeric Materials for Biomedical Applications

Superhydrophobic materials, with surfaces possessing permanent or metastable non-wetted states, are of interest for a number of biomedical and industrial applications. Here we describe how electrospinning or electrospraying a polymer mixture containing a biodegradable, biocompatible aliphatic polyester (e.g., polycaprolactone and poly(lactide-co-glycolide)), as the major component, doped with a hydrophobic copolymer composed of the polyester and a stearate-modified poly(glycerol carbonate) affords a superhydrophobic biomaterial. The fabrication techniques of electrospinning or electrospraying provide the enhanced surface roughness and porosity on and within the fibers or the particles, respectively. The use of a low surface energy copolymer dopant that blends with the polyester and can be stably electrospun or electrosprayed affords these superhydrophobic materials. Important parameters such as fiber size, copolymer dopant composition and/or concentration, and their effects on wettability are discussed. This combination of polymer chemistry and process engineering affords a versatile approach to develop application-specific materials using scalable techniques, which are likely generalizable to a wider class of polymers for a variety of applications.

Two- and three-dimensional superhydrophobic polymeric materials are prepared by electrospinning or electrospraying biodegradable polymers blended with a lower surface energy polymer of similar composition.

制造超疏水高分子材料生物医学应用

Superhydrophobic materials, with surfaces possessing permanent or metastable non-wetted states, are of interest for a number of biomedical and industrial ...

Fabricating Degradable Thermoresponsive Hydrogels on Multiple Length Scales via Reactive Extrusion, Microfluidics, Self-assembly, and Electrospinning

While various smart materials have been explored for a variety of biomedical applications (e.g., drug delivery, tissue engineering, bioimaging, etc.), their ultimate clinical use has been hampered by the lack of biologically-relevant degradation observed for most smart materials. This is particularly true for temperature-responsive hydrogels, which are almost uniformly based on polymers that are functionally non-degradable (e.g., poly(N-isopropylacrylamide) (PNIPAM) or poly(oligoethylene glycol methacrylate) (POEGMA)). As such, to effectively translate the potential of thermoresponsive hydrogels to the challenges of remote-controlled or metabolism-regulated drug delivery, cell scaffolds with tunable cell-material interactions, theranostic materials with the potential for both imaging and drug delivery, and other such applications, a method is required to render the hydrogels (if not fully degradable) at least capable of renal clearance following the required lifetime of the material. To that end, this protocol describes the preparation of hydrolytically-degradable hydrazone-crosslinked hydrogels on multiple length scales based on the reaction between hydrazide and aldehyde-functionalized PNIPAM or POEGMA oligomers with molecular weights below the renal filtration limit. Specifically, methods to fabricate degradable thermoresponsive bulk hydrogels (using a double barrel syringe technique), hydrogel particles (on both the microscale through the use of a microfluidics platform facilitating simultaneous mixing and emulsification of the precursor polymers and the nanoscale through the use of a thermally-driven self-assembly and cross-linking method), and hydrogel nanofibers (using a reactive electrospinning strategy) are described. In each case, hydrogels with temperature-responsive properties similar to those achieved via conventional free radical cross-linking processes can be achieved, but the hydrazone cross-linked network can be degraded over time to re-form the oligomeric precursor polymers and enable clearance. As such, we anticipate these methods (which may be generically applied to any synthetic water-soluble polymer, not just smart materials) will enable easier translation of synthetic smart materials to clinical applications.

Protocols are described for the fabrication of degradable thermoresponsive hydrogels based on hydrazone cross-linking of polymeric oligomers on the bulk scale, microscale, and nanoscale, the latter for preparation of both gel nanoparticles and nanofibers.

通过反应挤出、微流体、自组装和电纺丝制备多长尺度可降解 Thermoresponsive 水凝胶

While various smart materials have been explored for a variety of biomedical applications (e.g., drug delivery, tissue engineering, bioimaging, etc.), ...

Methods for the Self-integration of Megamolecular Biopolymers on the Drying Air-LC Interface

Living organisms that use water are always prone to drying in the environment. Their activities are driven by biopolymer-based micro- and macro-structures, as seen in the cases of moving water in vascular bundles and moisturizing water in skin layers. In this study, we developed a method for assessing the effect of aqueous liquid crystalline (LC) solutions composed of biopolymers on drying. As LC biopolymers have megamolecular weight, we chose to study polysaccharides, cytoskeletal proteins, and DNA. The observation of biopolymer solutions during drying under polarized light reveals milliscale self-integration starting from the unstable air-LC interface. The dynamics of the aqueous LC biopolymer solutions can be monitored by evaporating water from a one-side-open cell. By analyzing the images taken using cross-polarized light, it is possible to recognize the spatio-temporal changes in the orientational order parameter. This method can be useful for the characterization of not only artificial materials in various fields, but also natural living tissues. We believe that it will provide an evaluation method for soft materials in the biomedical and environmental fields.

A method for the drying-induced self-integration of megamolecular biopolymers on the air-liquid crystalline interface is provided here. This methodology will be useful not only for understanding the macroscopic potentials of biopolymers, but also as an evaluation method for soft materials in biomedical and environmental fields.

对干燥空气-LC接口Megamolecular生物大分子的自我整合方法

Living organisms that use water are always prone to drying in the environment. Their activities are driven by biopolymer-based micro- and ...

DNA Nanotubes as a Versatile Tool to Study Semiflexible Polymers

Mechanical properties of complex, polymer-based soft matter, such as cells or biopolymer networks, can be understood in neither the classical frame of flexible polymers nor of rigid rods. Underlying filaments remain outstretched due to their non-vanishing backbone stiffness, which is quantified via the persistence length (lp), but they are also subject to strong thermal fluctuations. Their finite bending stiffness leads to unique, non-trivial collective mechanics of bulk networks, enabling the formation of stable scaffolds at low volume fractions while providing large mesh sizes. This underlying principle is prevalent in nature (e.g., in cells or tissues), minimizing the high molecular content and thereby facilitating diffusive or active transport. Due to their biological implications and potential technological applications in biocompatible hydrogels, semiflexible polymers have been subject to considerable study. However, comprehensible investigations remained challenging since they relied on natural polymers, such as actin filaments, which are not freely tunable. Despite these limitations and due to the lack of synthetic, mechanically tunable, and semiflexible polymers, actin filaments were established as the common model system. A major limitation is that the central quantity lp cannot be freely tuned to study its impact on macroscopic bulk structures. This limitation was resolved by employing structurally programmable DNA nanotubes, enabling controlled alteration of the filament stiffness. They are formed through tile-based designs, where a discrete set of partially complementary strands hybridize in a ring structure with a discrete circumference. These rings feature sticky ends, enabling the effective polymerization into filaments several microns in length, and display similar polymerization kinetics as natural biopolymers. Due to their programmable mechanics, these tubes are versatile, novel tools to study the impact of lp on the single-molecule as well as the bulk scale. In contrast to actin filaments, they remain stable over weeks, without notable degeneration, and their handling is comparably straightforward.

Semiflexible polymers display unique mechanical properties that are extensively applied by living systems. However, systematic studies on biopolymers are limited since properties such as polymer rigidity are inaccessible. This manuscript describes how this limitation is circumvented by programmable DNA nanotubes, enabling experimental studies on the impact of filament rigidity.

DNA 纳米管作为研究半聚合物的万能工具

Mechanical properties of complex, polymer-based soft matter, such as cells or biopolymer networks, can be understood in neither the classical frame of ...

Melt Electrospinning Writing of Three-dimensional Poly(&#949;-caprolactone) Scaffolds with Controllable Morphologies for Tissue Engineering Applications

This tutorial reflects on the fundamental principles and guidelines for electrospinning writing with polymer melts, an additive manufacturing technology with great potential for biomedical applications. The technique facilitates the direct deposition of biocompatible polymer fibers to fabricate well-ordered scaffolds in the sub-micron to micro scale range. The establishment of a stable, viscoelastic, polymer jet between a spinneret and a collector is achieved using an applied voltage and can be direct-written. A significant benefit of a typical porous scaffold is a high surface-to-volume ratio which provides increased effective adhesion sites for cell attachment and growth. Controlling the printing process by fine-tuning the system parameters enables high reproducibility in the quality of the printed scaffolds. It also provides a flexible manufacturing platform for users to tailor the morphological structures of the scaffolds to their specific requirements. For this purpose, we present a protocol to obtain different fiber diameters using melt electrospinning writing (MEW) with a guided amendment of the parameters, including flow rate, voltage and collection speed. Furthermore, we demonstrate how to optimize the jet, discuss often experienced technical challenges, explain troubleshooting techniques and showcase a wide range of printable scaffold architectures.

This protocol serves as a comprehensive guideline to fabricate scaffolds via electrospinning with polymer melts in a direct writing mode. We systematically outline the process and define the appropriate parameter settings for achieving targeted scaffold architectures.

用于组织工程应用的三维聚 (ε-内) 支架的熔体静电纺丝

This tutorial reflects on the fundamental principles and guidelines for electrospinning writing with polymer melts, an additive manufacturing technology ...

Vapor Phase Deposition of Electroactive Poly(3,4-ethylenedioxythiophene) onto Electrospun Commodity Polymer Nanofibers

This study investigates the preparation of polyacrylonitrile (PAN) nanofibers through electrospinning to create highly porous and strong materials for applications in water purification, electrocatalysis, and biomedicine. The uniformly white PAN nanofiber mats were cut into 2 cm x 2 cm coupons to ensure consistency. After electrospinning, these nanofibers were coated with an electroactive polymer (EAP) using chemical vapor deposition, with iron (III) chloride (FeCl3) serving as an oxidant for polymerizing 3,4-ethylenedioxythiophene (EDOT) into poly(3,4-ethylenedioxythiophene) (PEDOT). The study examined the impact of different FeCl3 concentrations on PEDOT deposition on the PAN coupons. PEDOT deposition led to an increase in coupon weight. Scanning electron microscopy (SEM) revealed increases in the diameter of the nanofibers treated with increasing FeCl3 oxidant concentration, although higher FeCl3&#160;concentrations caused inter-fiber bridging, implying a concomitant decrease in inter-fiber spacing. Energy dispersive X-ray spectroscopy (EDS) was used to confirm the presence of Fe, Cl, and S in the nanofibers, with sulfur content rising with FeCl3&#160;concentration used, suggesting increased PEDOT deposition efficiency with increasing oxidant concentration. Mechanical testing showed that PEDOT-coated PAN fibers had improved tensile strength and toughness in the hydrated state compared to pure PAN nanofibers. These results highlight the crucial role of FeCl3&#160;concentration in influencing the morphology and properties of PAN-PEDOT composites, enhancing their suitability for applications such as water purification, tissue engineering, biosensing, catalysis, and energy storage.

This paper describes a simple technique for coating electrospun PAN nanofibers with electroactive polymers using vapor deposition. The effects of the oxidant FeCl&#8323; on the deposition of poly(3,4-ethylenedioxythiophene) coatings on PAN were investigated to understand and optimize polymer growth, fiber diameter, and overall mechanical strength of the nanofiber mats.

电活性聚（3,4-乙烯二氧噻吩）在电纺商品聚合物纳米纤维上的气相沉积

This study investigates the preparation of polyacrylonitrile (PAN) nanofibers through electrospinning to create highly porous and strong materials for ...

化学

Controlling Electrospun Polymer Morphology for Tissue Engineering Demonstrated Using hepG2 Cell Line

Electrospinning affords researchers the opportunity to fabricate reproducible micro to nanoscale polymer fibers. The 3D fibrous architecture of electrospun polymers is regarded as a structural imitation of the extracellular matrix (ECM). Hence, electrospun fibers fabricated from biocompatible polymers have been widely investigated by tissue engineering researchers for their potential role as an artificial ECM for guiding tissue growth both in vitro and in vivo. All cells are acutely sensitive to their mechanical environment. This has been demonstrated by the discovery of multiple mechanotransduction pathways intrinsically linked to the cytoskeletal actin filaments. The cytoskeleton acts as a mechanical sensor that can direct the functionality and differentiation of the host cell depending on the stiffness and morphology of its substrate. Electrospun fibers can be tuned both in terms of fiber size and morphology to easily modulate the mechanical environment within a fibrous polymer scaffold. Here, methods for electrospinning polycaprolactone (PCL) for three distinct morphologies at two different fiber diameters are described. The morphological fiber categories consist of randomly oriented fibers, aligned fibers, and porous cryogenically spun fibers, with 1 &#181;m and 5 &#181;m diameters. The methods detailed within this study are proposed as a platform for investigating the effect of electrospun fiber architecture on tissue generation. Understanding these effects will allow researchers to optimize the mechanical properties of electrospun fibers and demonstrate the potential of this technology more thoroughly.

This method provides the means to test different polycaprolactone fiber morphologies and topographies for the purpose of tissue engineering. Small and large fibers are fabricated with random orientations, aligned orientations, and also porous cryogenically electrospun structures and used as platforms for cell culture.

Electrospinning affords researchers the opportunity to fabricate reproducible micro to nanoscale polymer fibers. The 3D fibrous architecture of ...

Procedure for Fabricating Biofunctional Nanofibers

Electrospinning is an effective processing method for preparing nanofibers decorated with functional groups. Nanofibers decorated with functional groups may be utilized to study material-biomarker interactions i.e. act as biosensors with potential as single molecule detectors. We have developed an effective approach for preparing functional polymers where the functionality has the capacity of specifically binding with a model protein. In our model system, the functional group is 2,4-dinitrophenyl (DNP) and the protein is anti-DNP IgE (Immunoglobulin E). The functional polymer, &alpha;,&omega;-bi[2,4-dinitrophenyl caproic][poly(ethylene oxide)-b-poly(2-methoxystyrene)-b-poly(ethylene oxide)] (CDNP-PEO-P2MS-PEO-CDNP), is prepared by anionic living polymerization. The difunctional initiator utilized in the polymerization was prepared by electron transfer reaction of &alpha;-methylstyrene and potassium (mirror) metal. The 2-methoxystyrene monomer was added first to the initiator, followed by the addition of the second monomer, ethylene oxide, and finally the living polymer was terminated by methanol. The &alpha;,&omega;-dihydroxyl polymer [HO-PEO-P2MS-PEO-OH] was reacted with N-2,4-DNP-&isin;-amino caproic acid, by DCC coupling, resulting in the formation of &alpha;,&omega;-bi[2,4-dinitrophenylcaproic][poly(ethyleneoxide)-b-poly(2-methoxystyrene)-b-poly(ethylene oxide)] (CDNP-PEO-P2MS-PEO-CDNP). The polymers were characterized by FT-IR, 1H NMR and Gel Permeation Chromatography (GPC). The molecular weight distributions of the polymers were narrow (1.1-1.2) and polymers with molecular weights greater than 50,000 was used in this study. The polymers were yellow powders and soluble in tetrahydrofuran. A water soluble CDNP-PEO-P2MS-PEO-CDNP/ DMEG (dimethoxyethylene glycol) complex binds and achieves steady state binding with solution IgE within a few seconds. Higher molecular weight (water insoluble i.e. around 50,000) CDNP-PEO-P2MS-PEO-CDNP polymers, containing 1% single wall carbon nanotubes (SWCNT) were processed into electroactive nanofibers (100 nm to 500 nm in diameter) on silicon substrate. Fluorescence spectroscopy shows that anti-DNP IgE interacts with the nanofibers by binding with the DNP functional groups decorating the fibers. These observations suggest that appropriately functionalized nanofibers hold promise for developing biomarker detection device.

An efficient approach for preparing nanofibers decorated with functional groups capable of specifically interacting with proteins is described. The approach first requires the preparation of a polymer functionalized with the appropriate functional group. The functional polymer is fabricated into nanofibers by electrospinning. The effectiveness of the binding of the nanofibers with a protein is studied by confocal microscopy.

制作生物功能纳米纤维的过程

Electrospinning is an effective processing method for preparing nanofibers decorated with functional groups. Nanofibers decorated with functional groups ...