这项工作由中国国家自然科学基金 (21674018)、中国国家重点研究开发项目 (2016YFA0201702/2016YFA0201700) 和上海教育发展支持的 "曙光计划" 赞助。基金会和上海市教育委员会 (15SG30), 东华大学杰出青年教授项目 (A201302), 为中央大学的基础研究基金, 和111项目 (no. 111-2-04)。

警告: 请在使用前查阅所有相关的材料安全数据表。用于制备成型的几种化学药剂具有剧毒。请使用个人防护用品 (安全眼镜, 手套, 实验室大衣, 全长长裤, 和脚趾鞋). 
 1. 微流体纺丝 RSF 水溶液 <ol> <li> RSF 水纺涂料的制备 4 , 15 , 16 <ol> <li> 蚕茧脱胶 <ol> <li> 脱胶在 Na 2 CO 3 水溶液 (水中 0.5%) 中, 分别为100和 #176; C 为30分钟, 然后用去离子水洗涤丝绸去除丝胶. </li>
		</ol> </li> <li> 脱胶蚕茧的溶解 <ol> <li> 在空气中干燥脱胶茧丝绸; 然后在 9.0 M 溴化锂水溶液中溶解脱胶茧丝, 比例为 1:10 (w/v), 在40和 #176; C 为 2 h。例如, 每1克丝添加10毫升的溴化锂 ( 图 1a ). </li>
		</ol> </li> <li> 离心和筛选 <ol> <li> 通过去离子水稀释 RSF 溶液1.5 次。离心机和过滤器去除杂质。离心 RSF 溶液在250毫升瓶在4和 #176; C 为10分钟在 1234.8 x g. 使用20和 #181; m 过滤器和真空泵过滤 RSF 溶液。考虑试验效果, 双滤纸床更可取. </li>
		</ol> </li> <li> 透析 <ol> <li> 透析5和 #176 的去离子水中的 RSF 解决方案; C 使用纤维素透膜 (分子: 1.4万和 #177 2000) 的3天。RSF 溶液总容积约1升, 载入4透析袋。把这些透析袋放在水桶里, 里面装满了10升反渗透 (RO) 的去离子水. 
			注: 去离子水的 pH 值应高于 6, 以避免在浓缩过程中发生凝胶。去离子水的 pH 值不需要对此协议进行调整. </li>
		</ol> </li> <li> 集中 <ol> <li> 将 RSF 水溶液以5和 #176 的强制气流浓缩到 20%; c. 将3米 CaCl 2 水溶液添加到 RSF 溶液中至1.0 摩尔/克 Ca 2 + 最终浓度; 然后用强迫空气集中流到 38-47%. </li>
			<li> 将一滴 RSF 溶液放在玻片上, 然后在 105 #176 的烤箱中将其烘干2小时; C. 
			注: 与干燥前的重量相比, 剩余固体的重量百分比是蛋白质和 CaCl 的总浓度 2 。RSF 浓度是在扣除质量的 CaCl 2 后获得的。至少进行了四次重复测量。我们以前的研究表明, 钙的浓度 2 + 极大地影响了 RSF 水溶液的流变性能和可纺性。同时, Ca 2 + 的添加导致了有限的 #946;-页和 RSF 17 的聚合。在本机纺丝涂料中, CaCl 2 被认为在纺纱涂料贮存过程中起着重要作用, 避免了纺纱前的胶凝。 18 </li> </ol> </li> </ol> </li> <li> 微流控芯片的准备 8 19 <ol> <li> 准备掩 <ol> <li> 设计微型通道CAD 程序。打印 CAD 文件以生成高分辨率透明度 19 . </li>
		</ol> </li> <li> 准备模具 <ol> <li> 在化学罩中清洗玻璃幻灯片 <ol> <li>, 将浓硫酸和 30% 过氧化氢溶液 (10:1) 的混合溶液中的玻片煮沸, 在热板上20分钟. 
				注意: 硫酸和过氧化氢蒸气是非常有毒的. </li>
			</ol> </li> <li> 清洗玻璃幻灯片 <ol> <li> 使用去离子水冲洗玻璃玻片, 用高纯度氮气吹干。
			</ol> </li> <li> 涂膜 <ol> <li> 将 SU-8 的光刻胶涂在玻璃滑轨上, custom-built 涂层设备的间隙为100和 #181; m 在涂层条的下表面和玻璃的上表面之间. </li>
			</ol> </li> <li> 自旋涂层 <ol> <li> 在玻片上传播光刻胶, 在三十年代使用 40.3 x g 的旋转涂布机形成一个均匀的胶片。均匀膜的厚度约为85和 #181; m. </li>
			</ol> </li> <li> 固化 <ol> <li> 使用温度控制程序在烤箱中固化光刻胶。将室温温度提高到65和 #176; c 在2和 #176; c/分钟, 并保持在65和 #176; c 为2分钟, 继续升温从65和 #176; c 到95和 #176; c 和保持在95和 #176; c 为 15 min. 关闭烤箱, 自然降温到房间烤箱里的温度. </li>
			</ol> </li> <li> 紫外线曝光 <ol> <li> 将玻璃玻片的侧面与光刻胶一起暴露在十二年代使用透明胶片作为掩的光刻 19 。
				注意: 紫外光的波为 365 nm, 曝光能量为273.6 兆焦耳/cm 2 . 
				注意: 在使用 UV 灯和烤箱时, 采取适当的安全措施. </li>
			</ol> </li> <li> 按步骤1.2.2.5 中所述固化光刻胶. </li>
			<li> 开发 <ol> <li> 在三十年代开发人员解决方案中超声波清洗光刻胶. 用异丙醇和显影液冲洗玻片, 交替两个, 直到玻璃滑梯上没有沉淀. </li>
			</ol> </li> <li> 使用温度控制程序在烤箱中固化光刻胶。将室温温度提高到170和 #176; c 在2和 #176; c/分钟, 保持在170和 #176; c 为30分钟. 关闭烤箱, 自然冷却到烤箱室温. </li>
		</ol> </li> <li> 软光刻 <ol> <li> 将8.8 克液体烷 (硅橡胶) 预在模具和固化中, 在65和 #176 上30分钟; c, 和15分钟, 在80和 #176; c. 液态预由硅橡胶和固化剂组成 (通常在 10:1 (w/w)). </li>
		</ol> </li> <li> 冲孔 <ol> <li> 通过钻孔在通道的开始处通过该复制副本来打孔。钻头直径为 1.2 mm. </li>
		</ol> </li> <li> 密封 <ol> <li> 通过在两个硅橡胶层表面上进行氧等离子体处理, 将具有该通道的硅橡胶复制件与无图案的平坦的硅橡胶层密封. 
			注: 芯片的整体制备过程约需72小时. </li>
		</ol> </li> </ol> </li> <li> 制作 RSF 光纤 <ol> <li> 旋喷剂 <ol> <li> 将 RSF 旋涂料注入2和 #181 的微通道中; 由注射器泵送至/分钟. </li>
		</ol> </li> <li> 环境调节 <ol> <li> 将相对湿度调整为40和 #177; 5 RH% 或50和 #177; 5 RH% 使用加湿器。在40和 #177; 5 RH%, 作为纺纤维固化速度超过50和 #177; 5 RH%. </li>
		</ol> </li> <li> 生产 RSF 光纤 <ol> <li> 通过在微流体通道的出口处触摸 RSF 的下落, 将 RSF 纤维拉入空气中, 然后通过10厘米的空气间隙将其卷到滚筒上, 速度为3厘米/秒 ( 图 1b ).</li>
		</ol> </li> <li> 将 RSF 光纤存储在密封的干燥中24小时. </li>
		<li> 光纤后处理 <ol> <li> 在 80% ethano 中绘制4次在 0.9 mm -1 上的旋转纤维l custom-built 机解决方案, 然后保持所绘制的纤维固定, 浸泡在溶液中的纤维1小时。由于这种处理, 纤维的长度从原来的15毫米改为60毫米. </li>
		</ol> </li> <li> 准备用于特征描述的示例 <ol> <li> 将 post-treated 光纤固定在一个长度为 10 mm 的纸框架上。至少有20光纤需要测量, 包括在拉伸试验, SEM, FTIR, 和 WAXS。post-drawn 纤维的直径范围从5到10和 #181; m. 图 1 显示了纤维生产和 WAXD 特性的示意图。RSF 纤维的力学性能由 (25、#177、2)、#176、C、(45、#177; 5) 相对湿度为% 的材料测试系统检测。延伸率和测量长度分别为2毫米/分和1厘米. </li>
		</ol> </li> </ol> </li> </ol> 2。RSF 光纤晶体结构的同步辐射表征 <ol> <li> 同步辐射特性 4 13 17 <ol> <li> 调整光束 <ol> <li> 将 X 射线和光斑大小的波长调整为 0.07746 nm 和 3 x 2 和 #181; m 2 分别. 
			注: 该协议是使用 BL15U1 光束在上海同步辐射设施. </li>
		</ol> </li> <li> x 射线点的位置 <ol> <li> 查找 x 射线点的位置. 
			注: x 光点的位置由同步辐射装置的实验室技术员进行调整. </li>
		</ol> </li> <li> 标准样品测试: 二氧化铈 (ceo 2 ) <ol> <li> 测试标准样品 ceo 2 粉末。CeO 2 粉末的特征是计算圆中心和从样品到检测器的距离. </li>
		</ol> </li> <li> 示例准备 <ol> <li> 在纸框架上以 10 mm 的长度与对方并行修复 RSF 丝。将纸张框架粘附在测试阶段. 
			注意: 保持纤维水平. </li>
		</ol> </li> <li> SR WAXD 测试 <ol> <li> 打开快门 <ol> <li> 关闭光束站的门, 确保房间内没有人。打开 X 射线光源的快门. </li>
			</ol> </li> <li> 聚焦 <ol> <li> 将纤程稍稍移至焦点。通过软件 ( 图 1c ) 远程调整光纤沿 x、y、z 方向的位置. </li>
			</ol> </li> <li> 示例曝光 <ol> <li> 通过软件远程上下移动光纤, 直到它位于 x 射线点上。按软件上的 "开始" 按钮将光纤暴露给二十年代的 X 射线光束 ( 图 1c ). </li>
			</ol> </li> <li> 背景衍射 <ol> <li> 以二十年代的曝光时间来测试空气背景的衍射. 通过软件将光纤从 X 射线点远程移开。按下 #34; 启动和 #34; 软件上的按钮, 以暴露 X 射线光束到 #34; 空气介质和 #34; 二十年代. </li>
			</ol> </li> </ol> </li> </ol> </li> <li> WAXD 数据处理 13 <ol> <li> 软件校准 <ol> <li> 使用 FIT2D (V12.077) 处理 WAXD 数据。使用 CeO 2 粉末的衍射数据校准圆中心和 sample-to-detector 的距离. </li>
		</ol> </li> <li> 2 维衍射图案 <ol> <li> 使用 FIT2D (V12.077) 从光纤衍射图案中减去空气背景. </li>
		</ol> </li> <li> 结晶度和微晶尺寸 <ol> <li> 将衍射强度集成为散射角2和 #952 的函数;。通过自动峰值分离软件 (版本 4.12) 12 来执行强度积分的反褶积。结晶度, x c , 从关系估计: <img alt="Equation" src="/files/ftp_upload/56271/56271eq1.jpg"/> , 其中 i c 是晶体峰的综合强度和 i 的总和 是非晶晕的综合强度 4 , 11 。WAXD 模式的集成显示了 [200]、[020]、[002] 反射的峰值宽度。这些峰值的 FWHM 使用谢瑞和 #39 的公式 4 来确定沿 a、b 和 c 轴的微晶大小. </li>
		</ol> </li> <li> 确定微晶方向 <ol> <li> 根据 (020) 和 (210) 峰值 11 的方位积分计算微晶和无定形的取向。根据赫尔曼和 #39 的取向, 可以定量地计算晶体的取向。在这里, (020) 和 (210) 峰都装有两个高斯函数。较窄的一个是晶体方向和其他更广泛的是面向非晶态材料 13 。在这里, 对 RSF 纤维的微晶取向进行了比较, 利用了方位积分 (002) 峰值的半最大 (FWHM) 的全宽度. </li>
		</ol>
		</li>
	</ol>
	</li>
</ol>

<ol>
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P., Vollrath, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Liquid+crystals+and+flow+elongation+in+a+spider's+silk+production+line.">Liquid crystals and flow elongation in a spider's silk production line.</a> P Roy Soc B-Biol Sci. 266 (1418), 519-523 (1999).</li></ol>

作者没有什么可透露的。

在 RSF 溶液的透析过程中, pH 值对以下浓度过程至关重要。如果去离子水的 pH 值小于 6, RSF 溶液在浓缩过程中会更容易凝胶。为了避免凝胶, CaCl2被添加到 RSF 解决方案中。CaCl2的浓度是每重量 RSF 的1摩尔。
我们以前的工作证明了微流控 RSF 水溶液干纺的可能性8。微流控通道的几何形状是一个简化的单级指数函数。对于蜘蛛和蚕, 纺纱兴奋剂是通过一个两阶段指数回归旋转导管绘制的纤维形成1,20。在这里, 通过模仿蚕纺管道的二阶指数衰减函数, 设计了微流控通道的几何形状1。microﬂuidic 通道的宽度从2065µm 的初始宽度减少到265µm 的终端宽度, 延伸通道的长度为 21.5 mm。在上一篇文章中, 绘制的 RSF 纤维的直径为2µm。因此, 一捆 RSF 的螺纹必须用于机械测试和结构表征8。
实验表明, RSF 浓度和相对湿度对 RSF 纤维在干纺过程中的直径和显微组织有影响。RSF 纤维纺在 40% rh 显示更大的直径和更多的晶体结构比纤维纺在 50% rh。然而, 在 50% rh 纺丝的纤维有一个更高的晶体取向比在 40% rh 纺。结果可能与不同湿度的水蒸发速率有关。40% RH 的高蒸发率改善了分子内相互作用, 促进丝素蛋白从溶胶-凝胶到固丝纤维的快速相变。50% RH 的水蒸发率较低, 导致固化纤维中残留水含量较高。作为一个小分子润滑剂, 水促进丝素的取向, 使部分固化纤维拉伸到更细的纤维。这个过程帮助我们了解水是如何影响蚕丝纤维在本地纺纱过程中形成的。
post-treated RSF 纤维的力学性能优于脱胶丝4。后处理后, 纤维结晶急剧增加。post-treated RSF 纤维的 FWHM 比 as 纺纤维小。结果表明, 后处理改善了晶沿纤维轴的取向。然而, 后处理过程的复杂性限制了高强度 RSF 纤维的大量生产。
与传统的喷相比, 微流控通道非常适合模拟天然丝腺的几何形状。同时, 采用微流控纺丝法生产出具有优异力学性能的重组蜘蛛丝9。将剪切和拉伸部分集成在微流控纺丝芯片中, 以诱导蛋白质分子和纤维的组装和定位。因此, 微流控纺纱在生产高性能的动物丝绸以及其他合成纤维的解决方案中具有广阔的前景。然而, 微流控纺丝法只能生产单丝, 不能承受人工纤维的高产量。

在环境温度和压力下, 蜘蛛和蚕可以从水蛋白溶液中生产出优异的蚕丝纤维。剪切和伸展流动可诱导丝腺中的液晶纹理的形成1。近年来, 为了生产高强度的人造纤维, 模拟蜘蛛的纺丝工艺有着很大的兴趣。然而, 大量的蜘蛛丝蛋白不能生产效率和经济的养殖蜘蛛由于食人。大量的蚕丝绸可以通过耕作容易获得。否则, 蚕和蜘蛛有类似的纺纱工艺和氨基酸组成。因此, 蚕丝丝素被许多研究者选为人工动物丝的替代品。
蜘蛛和蚕通过他们的旋转导管挤出蛋白质溶液到空气中的纤维。沿着纺丝管道产生的高应力力很可能将丝素分子拉伸到更长的构象2。采用传统的湿纺和干纺工艺纺制了人造蚕丝纤维,3,4, 不考虑纺丝管产生的流体力。
首先, 采用微流控方法对蚕丝蛋白的组装进行了研究5,6。然后, 通过对剪切和伸展力的建模, 研究了 RSF 的微流体制备7,8。RSF 纤维的杨氏模量和直径可通过微流控湿纺纱进行调谐, 但拉伸纤维的抗拉强度小于100兆帕斯卡7。最后, 用微流控干纺法成功地制备了高强度 RSF 纤维, 但其直径仅2µm8。近年来, 微流控湿纺在高强度重组蜘蛛丝纤维生产中得到了成功的应用。空气中的 post-spinning 图改善了人造纤维的表面和内部缺陷9。
本文介绍了改进的微流控纺丝工艺在 RSF 光纤中的应用。它的目的是模仿蚕丝的纺纱过程, 包括纺纱涂料, 剪切力, 和干纺工艺。这种纺纱方法不仅可以生产高强度的人造蚕丝纤维, 而且可以调节纤维的直径。首先, 在具有二阶指数衰减的仿生通道中, RSF 纺涂料被剪切和拉长。其次, 研究了微流控干法纺丝过程中相对湿度 (RH) 对纤维形貌和性能的影响10。与传统的纺丝喷相比, 我们的微流控系统具有高度的仿生性, 可以用干湿纺法在室温下从溶液中产生高强度纤维。
由于同步辐射微 X 射线的高分辨率、亮度和高能性, 可以用来表征单个纤维的显微结构, 其直径为数微米4,11,12,13,14. 用 SR WAXD 技术计算了 RSF 纤维的结晶度、晶粒尺寸和晶体取向。

<table>
	<tbody>
		<tr>
			<td>B. mori Cocoons</td>
			<td>Farmer in Tongxiang, Zhejiang Province, China</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Sodium carbonate, anhydrous, 99.8%</td>
			<td>Shanghai Lingfeng Chemical Reagent Co., Ltd., China</td>
			<td></td>
			<td>Analytically Pure</td>
		</tr>
		<tr>
			<td>Lithium bromide, 99.1%</td>
			<td>Shanghai China Lithium Industrial Co., Ltd., China</td>
			<td></td>
			<td>Analytically Pure</td>
		</tr>
		<tr>
			<td>Calcium chloride, anhydrous, 96.0%</td>
			<td>Shanghai Lingfeng Chemical Reagent Co., Ltd., China</td>
			<td></td>
			<td>Analytically Pure</td>
		</tr>
		<tr>
			<td>Ethanol, anhydrous, 99.7%</td>
			<td>Sinopharm Group Chemical Reagent Co.,Ltd., China</td>
			<td>10009218</td>
			<td>Analytically Pure</td>
		</tr>
		<tr>
			<td>SU-8 photoresist</td>
			<td>MicroChem Corp., USA</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Developing solution</td>
			<td>MicroChem Corp., USA</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Sylgard 184</td>
			<td>Dow Corning, USA</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Isopropanol</td>
			<td>Shanghai Lingfeng Chemical Reagent Co., Ltd., China</td>
			<td></td>
			<td>Analytically Pure</td>
		</tr>
		<tr>
			<td>Concentrated sulfuric acid</td>
			<td>Pinghu Chemical Reagent Factory, China</td>
			<td></td>
			<td>Analytically Pure</td>
		</tr>
		<tr>
			<td>30 vol% hydrogen peroxide</td>
			<td>Shanghai Jinlu Chemical reagent Co., Ltd., China</td>
			<td></td>
			<td>Analytically Pure</td>
		</tr>
		<tr>
			<td>Acetone</td>
			<td>Shanghai Zhengxing Chemical Reagent Factory, China</td>
			<td></td>
			<td>Analytically Pure</td>
		</tr>
		<tr>
			<td>Oxygen plasma treatment</td>
			<td>DT-01, Suzhou Omega Machinery Electronic Technology Co., Ltd., China</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Syringe pump</td>
			<td>&#160;KD Scientific, USA</td>
			<td></td>
			<td>KDS 200P</td>
		</tr>
		<tr>
			<td>Humidifier</td>
			<td>SEN electric</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Driller</td>
			<td>Hangzhou Bo Yang Machinery Co., Ltd., China</td>
			<td></td>
			<td>bench drilling machine Z406c</td>
		</tr>
		<tr>
			<td>Material testing system</td>
			<td>Instron, USA</td>
			<td></td>
			<td>Model: 5565</td>
		</tr>
		<tr>
			<td>PeakFit</td>
			<td>Systat Software, Inc., USA</td>
			<td></td>
			<td>Version 4.12</td>
		</tr>
	</tbody>
</table>

microfluidic dry-spinning and characterization of regenerated silk fibroin fibers

该协议展示了一种仿蚕纺纱过程的方法。在本机纺纱过程中, 收缩纺丝管使蚕丝蛋白具有紧凑和有序的剪切和伸长力。在此, 设计了一种仿生微流控通道, 模拟了蚕纺管的特定几何形状。以高浓度掺杂的再生蚕丝丝素 (RSF) 为原料, 在室温和压力下通过微通道向干纺纤维挤出。在 post-treated 过程中, 在乙醇水溶液中提取和贮存成纱纤维。采用同步辐射 wide-angle x 射线衍射 (SR WAXD) 技术对单 RSF 纤维的显微组织进行了研究, 并将其固定在与 X 射线微的 RSF 纤维轴垂直的试样持有者身上。从 WAXD 数据计算了纤维的结晶度、晶粒尺寸和晶体取向。two-dimensional WAXD 模式赤道附近的衍射弧表明, post-treated RSF 纤维具有很高的取向度。

采用微流控纺丝方法成功地制备了高强度 RSF 纤维。在图 2中显示了拉伸 RSF 光纤 C44R40 的应力-应变曲线和 SEM 图像。在拉伸试验中测量了至少10纤维。根据纤维断裂应力和应变的平均值选择应力应变曲线。光纤的 WAXD 数据显示在图 3中。根据 WAXD 数据计算了结晶度和结晶取向。对于样品的指定, 我们用 C 和 R 分别介绍了纺丝涂料中 RSF 的浓度和相对湿度。例如, 从 44% RSF 纺丝涂料的纤维在40± 5% RH 被指定为 C44R40, 这是 post-drawn 在拉比4。其他纤维被改名了作为 C44R50, C47R40 和 C47R50 根据同样描述。
<img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/56271/56271fig1.jpg"> 
图 1:纤维生产示意图和结构描述.(a) 制备 RSF 溶液, (b) 微流控 RSF 纤维的纺丝工艺, (c) 同步辐射 RSF 单纤维实验装置。<a href="//ecsource-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/56271/56271fig1large.jpg" target="_blank">请单击此处查看此图的较大版本.</a>
<img alt="Figure 2" class="xfigimg" src="/files/ftp_upload/56271/56271fig2.jpg"> 
图 2:post-treated RSF 纤维的应力-应变曲线.插入显示 C44R40 的 SEM 图像。缩放条 = 10 µm。此图已从10中修改。<a href="//ecsource-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/56271/56271fig2large.jpg" target="_blank">请单击此处查看此图的较大版本.</a>
<img alt="Figure 3" class="xfigimg" src="/files/ftp_upload/56271/56271fig3.jpg"> 
图 3: post-treated RSF 光纤的 SR WAXD 数据.(a) post-treated RSF 单纤的二维 WAXD 模式: (A) C44R40, (b) C44R50, (c) C47R40, (d) C47R50, 和 (b) 脱胶b.(C) 一维 WAXD 数据的 post-treated RSF 纤维和脱胶B. 森丝, 这是在峰值反褶积中执行 (D)。此图已从引用10中进行了修改。<a href="//ecsource-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/56271/56271fig3large.jpg" target="_blank">请单击此处查看此图的较大版本.</a>

Watch this Scientific Journal Video about Microfluidic Dry-spinning and Characterization of Regenerated Silk Fibroin Fibers at JoVE.com

Microfluidic Dry-spinning and Characterization of Regenerated Silk Fibroin Fibers

微流控干纺及再生丝素纤维的表征

提出了一种微流体纺丝的协议, 并给出了再生丝素丝的显微组织表征。

The protocol demonstrates a method for mimicking the spinning process of silkworm. In the native spinning process, the contracting spinning duct enables ...

microfluidic-dry-spinning-characterization-regenerated-silk-fibroin

Nanyang Technological University

Research

JoVE Journal

Chemistry

9.7K 次观看.  Donghua University. 提出了一种微流体纺丝的协议, 并给出了再生丝素丝的显微组织表征。

视频: Microfluidic Dry-spinning and Characterization of Regenerated Silk Fibroin Fibers

Split-and-pool Synthesis and Characterization of Peptide Tertiary Amide Library

Peptidomimetics are great sources of protein ligands. The oligomeric nature of these compounds enables us to access large synthetic libraries on solid phase by using combinatorial chemistry. One of the most well studied classes of peptidomimetics is peptoids. Peptoids are easy to synthesize and have been shown to be proteolysis-resistant and cell-permeable. Over the past decade, many useful protein ligands have been identified through screening of peptoid libraries. However, most of the ligands identified from peptoid libraries do not display high affinity, with rare exceptions. This may be due, in part, to the lack of chiral centers and conformational constraints in peptoid molecules. Recently, we described a new synthetic route to access peptide tertiary amides (PTAs). PTAs are a superfamily of peptidomimetics that include but are not limited to peptides, peptoids and N-methylated peptides. With side chains on both &#945;-carbon and main chain nitrogen atoms, the conformation of these molecules are greatly constrained by sterical hindrance and allylic 1,3 strain. (Figure 1) Our study suggests that these PTA molecules are highly structured in solution and can be used to identify protein ligands. We believe that these molecules can be a future source of high-affinity protein ligands. Here we describe the synthetic method combining the power of both split-and-pool and sub-monomer strategies to synthesize a sample one-bead one-compound (OBOC) library of PTAs.

Peptide tertiary amides (PTAs) are a superfamily of peptidomimetics that include but are not limited to peptides, peptoids and N-methylated peptides. Here we describe a synthetic method which combines&#160;both split-and-pool and sub-monomer strategies to synthesize a one-bead one-compound library of PTAs.

分裂和池合成及肽叔酰胺图书馆表征

Peptidomimetics are great sources of protein ligands. The oligomeric nature of these compounds enables us to access large synthetic libraries on solid ...

科研

化学

Manufacturing of Three-dimensionally Microstructured Nanocomposites through Microfluidic Infiltration

Microstructured composite beams reinforced with complex three-dimensionally (3D) patterned nanocomposite microfilaments are fabricated via nanocomposite in&#64257;ltration of 3D interconnected microfluidic networks. The manufacturing of the reinforced beams begins with the fabrication of microfluidic networks, which involves layer-by-layer deposition of fugitive ink filaments using a dispensing robot, filling the empty space between filaments using a low viscosity resin, curing the resin and finally removing the ink.&#160;Self-supported 3D structures with other geometries and many layers (e.g.&#160;a few hundreds layers) could be built using this method. The resulting tubular micro&#64258;uidic networks are then infiltrated with thermosetting nanocomposite suspensions containing nanofillers (e.g.&#160;single-walled carbon nanotubes), and subsequently cured. The infiltration is done by applying a pressure gradient between two ends of the empty network (either by applying a vacuum or vacuum-assisted microinjection). Prior to the infiltration, the nanocomposite suspensions are prepared by dispersing nanofillers into polymer matrices using ultrasonication and three-roll mixing methods. The nanocomposites (i.e.&#160;materials infiltrated) are then solidified under UV exposure/heat cure, resulting in a 3D-reinforced composite structure. The technique presented here enables the design of functional nanocomposite macroscopic products for microengineering applications such as actuators and sensors.

Three-dimensional (3D) microstructured composite beams are fabricated through the directed and localized infiltration of nanocomposites into 3D porous microfluidic networks. The flexibility of this manufacturing method enables the utilization of different thermosetting materials and nanofillers in order to achieve a variety of functional 3D reinforced nanocomposite macroscopic products.

通过微流体渗透制备三维微结构纳米复合材料的制造

Microstructured composite beams reinforced with complex three-dimensionally (3D) patterned nanocomposite microfilaments are fabricated via nanocomposite ...

Synthesis and Characterization of Functionalized Metal-organic Frameworks

Metal-organic frameworks have attracted extraordinary amounts of research attention, as they are attractive candidates for numerous industrial and technological applications. Their signature property is their ultrahigh porosity, which however imparts a series of challenges when it comes to both constructing them and working with them. Securing desired MOF chemical and physical functionality by linker/node assembly into a highly porous framework of choice can pose difficulties, as less porous and more thermodynamically stable congeners (e.g., other crystalline polymorphs, catenated analogues) are often preferentially obtained by conventional synthesis methods. Once the desired product is obtained, its characterization often requires specialized techniques that address complications potentially arising from, for example, guest-molecule loss or preferential orientation of microcrystallites. Finally, accessing the large voids inside the MOFs for use in applications that involve gases can be problematic, as frameworks may be subject to collapse during removal of solvent molecules (remnants of solvothermal synthesis). In this paper, we describe synthesis and characterization methods routinely utilized in our lab either to solve or circumvent these issues. The methods include solvent-assisted linker exchange, powder X-ray diffraction in capillaries, and materials activation (cavity evacuation) by supercritical CO2 drying. Finally, we provide a protocol for determining a suitable pressure region for applying the Brunauer-Emmett-Teller analysis to nitrogen isotherms, so as to estimate surface area of MOFs with good accuracy.

Synthesis, activation, and characterization of intentionally designed metal-organic framework materials is challenging, especially when building blocks are incompatible or unwanted polymorphs are thermodynamically favored over desired forms. We describe how applications of solvent-assisted linker exchange, powder X-ray diffraction in capillaries and activation via supercritical CO2 drying, can address some of these challenges.

功能化的合成与表征金属 - 有机骨架

Metal-organic frameworks have attracted extraordinary amounts of research attention, as they are attractive candidates for numerous industrial and ...

Preparation and Characterization of SDF-1&#945;-Chitosan-Dextran Sulfate Nanoparticles

Chitosan (CS) and dextran sulfate (DS) are charged polysaccharides (glycans), which form polyelectrolyte complex-based nanoparticles when mixed under appropriate conditions. The glycan nanoparticles are useful carriers for protein factors, which facilitate the in vivo delivery of the proteins and sustain their retention in the targeted tissue. The glycan polyelectrolyte complexes are also ideal for protein delivery, as the incorporation is carried out in aqueous solution, which reduces the likelihood of inactivation of the proteins. Proteins with a heparin-binding site adhere to dextran sulfate readily, and are, in turn, stabilized by the binding. These particles are also less inflammatory and toxic when delivered in vivo. In the protocol described below, SDF-1&#945; (Stromal cell-derived factor-1&#945;), a stem cell homing factor, is first mixed and incubated with dextran sulfate. Chitosan is added to the mixture to form polyelectrolyte complexes, followed by zinc sulfate to stabilize the complexes with zinc bridges. The resultant SDF-1&#945;-DS-CS particles are measured for size (diameter) and surface charge (zeta potential). The amount of the incorporated SDF-1&#945; is determined, followed by measurements of its in vitro release rate and its chemotactic activity in a particle-bound form.

The objective of this protocol is to incorporate SDF-1&#945;, a stem cell homing factor, into dextran sulfate-chitosan nanoparticles. The resultant particles are measured for their size and zeta potential, as well as the content, activity, and in vitro release rate of SDF-1&#945; from the nanoparticles.

SDF-1α - 壳聚糖硫酸葡聚糖纳米粒子的制备与表征

Chitosan (CS) and dextran sulfate (DS) are charged polysaccharides (glycans), which form polyelectrolyte complex-based nanoparticles when mixed under ...

Synthesis and Characterization of Supramolecular Colloids

Control over colloidal assembly is of utmost importance for the development of functional colloidal materials with tailored structural and mechanical properties for applications in photonics, drug delivery and coating technology. Here we present a new family of colloidal building blocks, coined supramolecular colloids, whose self-assembly is controlled through surface-functionalization with a benzene-1,3,5-tricarboxamide (BTA) derived supramolecular moiety. Such BTAs interact via directional, strong, yet reversible hydrogen-bonds with other identical BTAs. Herein, a protocol is presented that describes how to couple these BTAs to colloids and how to quantify the number of coupling sites, which determines the multivalency of the supramolecular colloids. Light scattering measurements show that the refractive index of the colloids is almost matched with that of the solvent, which strongly reduces the van der Waals forces between the colloids. Before photo-activation, the colloids remain well dispersed, as the BTAs are equipped with a photo-labile group that blocks the formation of hydrogen-bonds. Controlled deprotection with UV-light activates the short-range hydrogen-bonds between the BTAs, which triggers the colloidal self-assembly. The evolution from the dispersed state to the clustered state is monitored by confocal microscopy. These results are further quantified by image analysis with simple routines using ImageJ and Matlab. This merger of supramolecular chemistry and colloidal science offers a direct route towards light- and thermo-responsive colloidal assembly encoded in the surface-grafted monolayer.

A protocol for the synthesis and characterization of colloids coated with supramolecular moieties is described. These supramolecular colloids undergo self-assembly upon the activation of the hydrogen-bonds between the surface-anchored molecules by UV-light.

超分子胶体的合成与表征

Control over colloidal assembly is of utmost importance for the development of functional colloidal materials with tailored structural and mechanical ...

Highly Stable, Functional Hairy Nanoparticles and Biopolymers from Wood Fibers: Towards Sustainable Nanotechnology

Nanoparticles, as one of the key materials in nanotechnology and nanomedicine, have gained significant importance during the past decade. While metal-based nanoparticles are associated with synthetic and environmental hassles, cellulose introduces a green, sustainable alternative for nanoparticle synthesis. Here, we present the chemical synthesis and separation procedures to produce new classes of hairy nanoparticles (bearing both amorphous and crystalline regions) and biopolymers based on wood fibers. Through periodate oxidation of soft wood pulp, the glucose ring of cellulose is opened at the C2-C3 bond to form 2,3-dialdehyde groups. Further heating of the partially oxidized fibers (e.g., T = 80 &#176;C) results in three products, namely fibrous oxidized cellulose, sterically stabilized nanocrystalline cellulose (SNCC), and dissolved dialdehyde modified cellulose (DAMC), which are well separated by intermittent centrifugation and co-solvent addition. The partially oxidized fibers (without heating) were used as a highly reactive intermediate to react with chlorite for converting almost all aldehyde to carboxyl groups. Co-solvent precipitation and centrifugation resulted in electrosterically stabilized nanocrystalline cellulose (ENCC) and dicarboxylated cellulose (DCC). The aldehyde content of SNCC and consequently surface charge of ENCC (carboxyl content) were precisely controlled by controlling the periodate oxidation reaction time, resulting in highly stable nanoparticles bearing more than 7 mmol functional groups per gram of nanoparticles (e.g., as compared to conventional NCC bearing &#60;&#60; 1 mmol functional group/g). Atomic force microscopy (AFM), transmission electron microscopy (TEM), and scanning electron microscopy (SEM) attested to the rod-like morphology. Conductometric titration, Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR), dynamic light scattering (DLS), electrokinetic-sonic-amplitude (ESA) and acoustic attenuation spectroscopy shed light on the superior properties of these nanomaterials.

Synthesis schemes to prepare highly stable wood fiber-based hairy nanoparticles and functional cellulose-based biopolymers have been detailed.

高稳定性，功能性毛纳米粒子和木纤维生物聚合物:迈向可持续纳米技术

Nanoparticles, as one of the key materials in nanotechnology and nanomedicine, have gained significant importance during the past decade. While ...

Low-energy Cathodoluminescence for (Oxy)Nitride Phosphors

Nitride and oxynitride (Sialon) phosphors are good candidates for the ultraviolet and visible emission applications. High performance, good stability and flexibility of their emission properties can be achieved by controlling their composition and dopants. However, a lot of work is still required to improve their properties and to reduce the production cost. A possible approach is to correlate the luminescence properties of the Sialon particles with their local structural and chemical environment in order to optimize their growth parameters and find novel phosphors. For such a purpose, the low-voltage cathodoluminescence (CL) microscopy is a powerful technique. The use of electron as an excitation source allows detecting most of the luminescence centers, revealing their luminescence distribution spatially and in depth, directly comparing CL results with the other electron-based techniques, and investigating the stability of their luminescence properties under stress. Such advantages for phosphors characterization will be highlighted through examples of investigation on several Sialon phosphors by low-energy CL.

Low-energy Cathodoluminescence for OxyNitride Phosphors

An excellent chemical and luminescence stabilities of (oxy)nitride phosphors present it as an promising alternative to currently used sulfide and oxide phosphors. In this paper, we present the way to investigate its local luminescence properties using low-energy cathodoluminescence (CL).

低能量的阴极射线（氧）氮化物荧光粉

Nitride and oxynitride (Sialon) phosphors are good candidates for the ultraviolet and visible emission applications. High performance, good stability and ...

Microfluidic-based Synthesis of Covalent Organic Frameworks (COFs): A Tool for Continuous Production of COF Fibers and Direct Printing on a Surface

Covalent Organic Frameworks (COFs) are a class of porous covalent materials which are frequently synthesized as unprocessable crystalline powders. The first COF was reported in 2005 with much effort centered on the establishment of new synthetic routes for its preparation. To date, most available synthetic methods for COF synthesis are based on bulk mixing under solvothermal conditions. Therefore, there is increasing interest in developing systematic protocols for COF synthesis that provide for fine control over reaction conditions and improve COF processability on surfaces, which is essential for their use in practical applications. Herein, we present a novel microfluidic-based method for COF synthesis where the reaction between two constituent building blocks, 1,3,5-benzenetricarbaldehyde (BTCA) and 1,3,5-tris(4-aminophenyl)benzene (TAPB), takes place under controlled diffusion conditions and at room temperature. Using such an approach yields sponge-like, crystalline fibers of a COF material, hereafter called MF-COF. The mechanical properties of MF-COF and the dynamic nature of the approach allow the continuous production of MF-COF fibers and their direct printing onto surfaces. The general method opens new potential applications requiring advanced printing of 2D or 3D COF structures on flexible or rigid surfaces.

Microfluidic-based Synthesis of Covalent Organic Frameworks COFs: A Tool for Continuous Production of COF Fibers and Direct Printing on a Surface

We present a novel microfluidic-based method for synthesis of covalent organic frameworks (COFs). We demonstrate how this approach can be used to produce continuous COF fibers, and also 2D or 3D COF structures on surfaces.

基于微流体的共价有机骨架（COFs）的合成:用于连续生产COF纤维和直接印刷在表面上的工具

Covalent Organic Frameworks (COFs) are a class of porous covalent materials which are frequently synthesized as unprocessable crystalline powders. The ...

Preparation and Characterization of C60/Graphene Hybrid Nanostructures

Physical thermal deposition in a high vacuum environment is a clean and controllable method for fabricating novel molecular nanostructures on graphene. We present methods for depositing and passively manipulating C60 molecules on rippled graphene that advance the pursuit of realizing applications involving 1D C60/graphene hybrid structures. The techniques applied in this exposition are geared towards high vacuum systems with preparation areas capable of supporting molecular deposition as well as thermal annealing of the samples. We focus on C60 deposition at low pressure using a homemade Knudsen cell connected to a scanning tunneling microscopy (STM) system. The number of molecules deposited is regulated by controlling the temperature of the Knudsen cell and the deposition time. One-dimensional (1D) C60 chain structures with widths of two to three molecules can be prepared via tuning of the experimental conditions. The surface mobility of the C60 molecules increases with annealing temperature allowing them to move within the periodic potential of the rippled graphene. Using this mechanism, it is possible to control the transition of 1D C60 chain structures to a hexagonal close packed quasi-1D stripe structure.

Preparation and Characterization of C60/Graphene Hybrid Nanostructures

Here we present a protocol for the fabrication of C60/graphene hybrid nanostructures by physical thermal evaporation. Particularly, the proper manipulation of deposition and annealing conditions allow the control over the creation of 1D and quasi 1D C60 structures on rippled graphene.

C 型60/石墨烯混合纳米结构的制备与表征

Physical thermal deposition in a high vacuum environment is a clean and controllable method for fabricating novel molecular nanostructures on graphene. We ...

Microfluidic Preparation of Liquid Crystalline Elastomer Actuators

This paper focuses on the microfluidic process (and its parameters) to prepare actuating particles from liquid crystalline elastomers. The preparation usually consists in the formation of droplets containing low molar mass liquid crystals at elevated temperatures. Subsequently, these particle precursors are oriented in the flow field of the capillary and solidified by a crosslinking polymerization, which produces the final actuating particles. The optimization of the process is necessary to obtain the actuating particles and the proper variation of the process parameters (temperature and flow rate) and allows variations of size and shape (from oblate to strongly prolate morphologies) as well as the magnitude of actuation. In addition, it is possible to vary the type of actuation from elongation to contraction depending on the director profile induced to the droplets during the flow in the capillary, which again depends on the microfluidic process and its parameters. Furthermore, particles of more complex shapes, like core-shell structures or Janus particles, can be prepared by adjusting the setup. By the variation of the chemical structure and the mode of crosslinking (solidification) of the liquid crystalline elastomer, it is also possible to prepare actuating particles triggered by heat or UV-vis irradiation.

This article describes the microfluidic process and parameters to prepare actuating particles from liquid crystalline elastomers. This process allows the preparation of actuating particles and the variation of their size and shape (from oblate to strongly prolate, core-shell, and Janus morphologies) as well as the magnitude of actuation.

液晶弹性体致动器的微流控制备

This paper focuses on the microfluidic process (and its parameters) to prepare actuating particles from liquid crystalline elastomers. The preparation ...