作者感谢来自中国中央政府的 "千少年全球人才" 奖的资助, 来自江苏省政府的 "双创" 奖、工程学院创办基金和应用科学, 南京大学, 中国, 由 "天基" 基金会授予, 由江苏省自然科学基金 (PAPD) 优先学术项目发展基金资助。

注意: 由于使用有机溶剂, 所有操作都应在化学油烟机中进行。由于使用了高电压, 避免在电源通电时与设备进行身体接触。使用所有适当的安全做法, 如使用个人防护设备 (安全眼镜, 手套, 实验室大衣, 全长长裤, 和闭合脚趾鞋)。查阅所有相关的材料安全数据表 (MSDS)。
1. 材料的设置
<ol><li>要准备 QDs 溶液, 溶解10毫克疏水性 (荧光发射峰值波长 = 605 nm, 用作这里的模型纳米晶) 在20毫升有机溶剂 (氯仿生产球形胶束形状或 THF 产生蠕虫状胶束形状) 和漩涡二十年代。</li>
	<li>制备 ps-peg 溶液, 溶解100毫克 ps peg (两亲嵌段共聚物, 9.5 kDA ps 节和 18.0 kDA PEG 段) 在10毫升有机溶剂 (氯仿生产球形胶束形状或 THF 生产蠕虫状胶束形状)。用涡流1分钟 (氯仿) 或浴油脂实验混合溶液, 2 分钟 (THF)。</li>
	<li>混合1毫升溶液和1毫升 PS-PEG 溶液和涡流1分钟. 将混合物加入注射器 A。注射器是用聚四氟乙烯做的。</li>
	<li>为制备 pva 溶液, 在60–80°c 的热水浴中, 将400毫克 pva (13-23 kDa, 87-89% 水解) 在10毫升水中溶解, 第4-5 h. 允许 PVA 溶液在使用前冷却到室温。</li>
	<li>在注射器 B 中加入5毫升 PVA 溶液。注射器是用聚四氟乙烯做的。</li>
</ol>2. 设备的设置
<ol><li>将内毛细管插入外毛细管组件中, 轻轻拧入原位。不要过度收紧。图 2显示了同轴电喷雾系统的总体设置。内毛细针为27克 (外径500µm; 内径300µm) 不锈钢毛细管, 外针为20克 (外径1000µm; 内径500µm) 不锈钢三路连接器。所用的聚四氟乙烯油管内径为1.8 毫米。</li>
	<li>在注射器泵上装载注射器 a, 如图 2所示。用聚四氟乙烯管将注射器 A 连接到电喷雾同轴喷嘴的内不锈钢毛细管中。</li>
	<li>在注射器泵 b 上装载注射器 b, 如图 2所示。用聚四氟乙烯管将注射器 B 与电喷雾同轴喷嘴的外不锈钢毛细管连接起来。</li>
	<li>将电喷雾同轴喷嘴尖端放置在接地钢环上方约0.8 厘米 (直径为1.5 厘米)。</li>
	<li>在同轴喷嘴下方放置一个约10厘米的玻璃收集盘。</li>
	<li>关闭电源后, 将接地线 (图 2中的黑线) 连接到接地的钢环上。</li>
	<li>关闭电源后, 使用金属鳄鱼夹子将电源的正端 (图 2中的红线) 连接到同轴喷嘴的内针。</li>
</ol>3. 胶束纳米晶的生产
<ol><li>将注射器泵的速度设置为0.6 毫升/小时。</li>
	<li>将注射器泵的速度设置为1.5 毫升/小时。</li>
	<li>启动两个注射器泵, 并等待其各自的流量稳定。在喷嘴上以稳态速率形成的水滴表示稳定的流速。这通常发生在六十年代后, 启动注射器泵。 注: 在电喷雾同轴喷嘴中, 油管内不应有气泡, 液滴应形成。</li>
	<li>打开电源, 将正高压应用于电喷雾同轴喷嘴。调整在 5–9 kV 范围内的应用电压, 直到一个凹锥射流 (即, 一个会聚射流, 俗称为 ' 泰勒锥 ') 在同轴喷嘴的尖端观察 (如图 3a的插入所示)。 注意: 当高压应用时, 一定不要接触电喷雾喷嘴。遵循适当的安全防范措施。 注: 应用电压不足会导致喷嘴端部的水滴形成 (如图 3b的插入所示), 而施加电压过高会导致喷嘴与接地钢环之间产生电弧。</li>
	<li>在稳定的泰勒锥 (图 3a) 获得后, 将10毫升去离子水添加到干净的收集盘中, 并替换安装中的玻璃收集盘。新菜将收集胶束纳米晶产品。</li>
	<li>在一定的时间内运行胶束纳米晶生产过程 (大约40分钟生产球形胶束形状或大约90分钟产生蠕虫状胶束形状)。然后从电喷雾喷嘴下面取出收集皿。</li>
	<li>停止注射器泵 A 和 B。</li>
	<li>关闭高压电源。</li>
	<li>允许有机溶剂蒸发 (在通风罩) 从发现的收集盘过夜。 注: 从胶束纳米晶产品的表征结果看, 隔夜蒸发足以去除有机溶剂, 获得质量好的产品。</li>
	<li>最后, 将胶束纳米晶产品转移到15毫升离心管中进行表征 (例如、荧光光谱、动态光散射、透射电镜和热分析)、应用或存储。将最终的胶束纳米晶产品存储在冰箱中4摄氏度。 注: 该产品在这个贮存条件下可保持稳定至少一个月。</li>
</ol>

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作者没有什么可透露的。

本工作所描述的胶束纳米晶的制备方法是将自顶向下的电喷雾、自下而上的自我组装和溶剂型结构控制相结合。采用同轴喷嘴尖端形成的泰勒锥, 是一种有效、方便的质量控制方法。这是因为一个正确形成的泰勒锥表示在电力和表面张力之间的平衡 (或接近平衡), 这反过来表明, 成功形成的微型反应堆 (均匀超细滴) 为自组装反应发生自发.如果泰勒锥没有正确的形成, 你应该调整电源电压和注射器泵的流量, 同时确保同轴喷嘴尖端和接地钢环之间的距离是适当的, 直到正确形成泰勒锥体被观察。获得稳定的泰勒锥的一种方法是增加高压, 直到电子在电喷雾喷嘴尖端和接地钢环之间开始电弧。此时, 通过 0.5–1.5 kV 降低电喷雾电压, 不发生电弧。如果一个稳定的泰勒锥仍然没有形成, 仔细观察从喷嘴尖端出现的液体。如果液体滴偶尔出现, 系统地减少注射器泵的流速, 直到观察到一个稳定的泰勒锥。如果喷嘴尖端没有观察到水滴, 系统地增加注射器泵的流速, 直到观察到稳定的泰勒锥为止。此外, 同轴喷嘴尖端和产品收集皿之间的距离应保持在适当的价值。如果距离太小, 有机溶剂的蒸发速度太慢, 胶束纳米晶形成过程会受到不利影响;另一方面, 如果距离太大, 大量的材料可能会在生产过程中以气溶胶的形式丢失。最后, 聚合物和 QDs 的浓度应保持在适当的值。如果聚合物浓度过低, 胶束可能不会形成, 因为需要达到一个临界聚合物浓度的胶束形成;如果聚合物浓度过高, 几乎所有形成的胶束都是空胶束。类似地, 如果浓度过低, 几乎所有形成的胶束都是空胶束。如果浓度太高, 许多 QDs 不会被封装成胶束。
所产生的胶束纳米晶可以在每个胶束中有多个纳米晶, 允许多功能 (例如, 当 QDs 和 SPIONs 共同封装时荧光和磁性) 或协同效应 (例如, 变色用两种不同的荧光色共封装 QDs 形成的复合纳米颗粒)8,9,10,14,15,16,17 ,18。该生产方法还可用于封装其他纳米材料, 如碳纳米管和金纳米棒。蠕虫状胶束可以提供最小化的非特异细胞吸收, 从而增强生物靶向13。胶束纳米晶产品可以很容易地与各种生物分子结合使用已建立良好的 bioconjugation 技术, 并用于生物学成像, 检测, 操作和治疗。
目前的制造工艺允许生产球形和蜗杆状的胶束纳米晶。采用 THF 为有机溶剂, 反应时间长, 可实现蜗杆形状。此外, 还有人指出, 当使用高分子浓度 (如20 毫克/毫升以上的协议), 即使在短反应时间 (以 THF 作为有机溶剂), 一些蠕虫状胶束可以形成。然而, 使用如此高的聚合物浓度很容易导致聚集。
目前制备工艺的一个局限性是, 胶束中的纳米晶封装仍然是有限的 (以 THF 为有机溶剂, 空胶束的百分比为 50%, 封装有两个或多个纳米晶的胶束的百分比为 ~20%、用氯仿作为有机溶剂, 空胶束的百分比为 ~ 80%, 封装有两个或多个纳米晶的胶束的百分比为 ~ 10%)13, 尽管它通常会给出改进的纳米晶封装效果。与传统的膜水化方法相比 (在实验室进行的试验中采用相似的材料条件给予 > 80% 的空胶束)。从根本上说, 这种限制是因为, 与小分子染料和药物相比, 纳米晶的体积很大, 因而在运输速率上受到限制。换言之, 纳米晶封装受动力学的限制, 而不是热力学13。当大型物体 (在这种情况下, 纳米晶与几纳米直径) 被封装成小胶囊 (在这种情况下, 直径为 35 nm 的胶束) 时, 传输限制效应尤为明显。因此, 进一步改进纳米晶封装将是未来工作的一个主要目标。目前制造过程的另一个局限性是它尚未完全连续。这主要是因为该过程中的产品集合部分仍然是批处理过程, 这将在改进版的过程中加以解决。

纳米晶如半导体量子点 (QDs) 和超顺磁性氧化铁纳米粒子 (SPIONs) 显示了生物检测、成像、操作和治疗的巨大潜力1, 2, 3,4,5,6。将一个或多个纳米晶封装成胶束已成为一种广泛使用的方法, 用于将纳米晶与生物环境 (3,6) 接口。由此形成的胶束纳米晶 (胶束与纳米晶封装) 已成为一个新兴的类 nanobiomaterials7,8,9,10。通常使用的方法来制造封装各种材料的胶束 (例如, 纳米晶, 小分子药物和染料) 包括膜水化, 透析, 和其他几个7,11。
本工作描述了一种基于自顶向下的电喷雾, 自下而上的自我组装和溶剂介导的结构控制的制备胶束纳米晶的方法。与胶束纳米晶的其它制备方法相比, 本方法具有以下几个有益的特点: (1) 它是一个很大的连续生产过程。这一特点主要是因为我们的方法中使用了电喷雾形成乳液滴。相比之下, 一些其他方法使用涡流或超声波来形成乳化液滴, 从而使这些方法在自然界中的批处理过程为12。(2) 产生的产品具有水分散性高、胶体稳定性好、封装纳米晶的完好的物理功能。与其它胶束封装方法相比, 该工艺往往能使产品具有优异的质量, 在很大程度上是因为电喷雾能形成超细和均匀的乳化液滴。(3) 产品的结构, 包括胶束形状和封装的纳米晶的数量, 可以由溶剂控制, 这比其他控制方式, 如改变所使用的两亲聚合物, 更便宜, 并能产生不仅是通常可用的球形胶束形状, 但蠕虫样胶束的形状通过胶束融合13。由此形成的蜗杆状胶束纳米晶可大大减少非特异的细胞吸收比球形对应物13。另一方面, 值得指出的是, 这种方法需要安装一个电喷雾装置, 它在技术上比其他方法的需要更严格 (虽然远不受禁止)。
本发明的方法包括首先生成具有均匀尺寸的超细液体 (通常为水中乳化液) 液滴, 其次是有机溶剂的蒸发, 导致自组装形成胶束纳米晶 (图1).电喷雾装置具有同轴构型使用同心针: 油相, 其中含有两亲嵌段共聚物和疏水性纳米晶溶解于有机溶剂, 被送到内针 (27 克不锈钢毛细管) 用注射器泵;水相, 其中含有溶解在水中的表面活性剂, 被交付到外针 (20 克不锈钢三路连接器) 与第二注射器泵。高压适用于同轴喷嘴。由于电动力克服了液体中的表面张力和惯性应力, 产生了均匀尺寸的超细水滴。每个液滴基本上都是一个 ' 微反应器 ', 在其中, 当有机溶剂蒸发后, 自组装的反应会自发地由于疏水性的相互作用而发生。使用不同的有机溶剂导致不同结构的胶束纳米晶: 水不溶性有机溶剂氯仿导致球形胶束形状, 而水混溶有机溶剂 THF 长反应时间导致蠕虫样胶束形状随着增强的纳米晶封装。

<table>
	<tbody>
		<tr>
			<td>Hydrophobic quantum dots</td>
			<td>Ocean Nanotech</td>
			<td>QSP</td>
			<td>Solid hydrophobic CdSe/ZnS quantum dots. Peak fluorescence emission wavelength is 605 nm.</td>
		</tr>
		<tr>
			<td>Poly(styrene)-b-poly(ethylene glycol) (PS-PEG)</td>
			<td>Sigma-Aldrich</td>
			<td>666476-500MG</td>
			<td>Molecular weight of PS segment is 9.5 kDa and that of PEG segment is 18.0 kDa.</td>
		</tr>
		<tr>
			<td>Poly(vinyl alcohol) (PVA)</td>
			<td>Sigma-Aldrich</td>
			<td>363170-500G</td>
			<td>Molecular weight 13&#8211;23 kDa, 87&#8211;89% hydrolyzed.</td>
		</tr>
		<tr>
			<td>Tetrahydrofuran (THF)</td>
			<td>Sinopharma Chemical Reagent</td>
			<td>80124418</td>
			<td></td>
		</tr>
		<tr>
			<td>Chloroform</td>
			<td>Sinopharma Chemical Reagent</td>
			<td>40007960</td>
			<td></td>
		</tr>
		<tr>
			<td>Syringe pumps</td>
			<td>Bao Ding Shen Chen</td>
			<td>SPLab01</td>
			<td></td>
		</tr>
		<tr>
			<td>Tubing</td>
			<td>Shanghei Lai Xing</td>
			<td></td>
			<td>2 mm outer diameter and 1.8 mm inner diameter PTFE tubing.</td>
		</tr>
		<tr>
			<td>Syringes</td>
			<td>Yi Ming</td>
			<td>5.CC</td>
			<td>5 mL disposable syringe made of PTFE.</td>
		</tr>
		<tr>
			<td>High voltage power supply</td>
			<td>Dong Wen</td>
			<td>DW Series</td>
			<td>Direct current power supply (0&#8211;50 kV range).</td>
		</tr>
		<tr>
			<td>Electrospray coaxial nozzle</td>
			<td>Hunan Chang Sha Na Yi</td>
			<td></td>
			<td>Stainless steel assembly. Inner capillary needle was a 27 gauge (outer diameter 500 &#956;m; inner diameter 300 &#956;m). Outer capillary was a 20 gauge (outer diameter 1,000 &#956;m; inner diameter 500 &#956;m).</td>
		</tr>
		<tr>
			<td>Vortexer</td>
			<td>Xi&#39;an HEB Biotechnology Co., Ltd. China</td>
			<td>MX-S</td>
			<td>MX-S with wide speed range of 0&#8211;2,500 rpm, stepless speed regulation, touch and continuous operations.</td>
		</tr>
		<tr>
			<td>Steel ring</td>
			<td>Yiwu Wan Tu</td>
			<td></td>
			<td>Rings with a range of diameters (0.8&#8211;1.8 cm) can be constructued. For example, a 1.3 cm diameter ring was constructed by curling an approximately 25 cm (length) of 0.5-mm diamter (24 gauge, AWG) steel wire.</td>
		</tr>
		<tr>
			<td>Glass collecting dish</td>
			<td>Grainger</td>
			<td>1u5084</td>
			<td>25-mm height and 120-mm diameter glass dish.</td>
		</tr>
		<tr>
			<td>15 mL centrifuge tube</td>
			<td>Jiangsu Xinkang Medical Instrument Co., Ltd.</td>
			<td>X-407</td>
			<td>Centrifuge tube is made of transparent polypropylene (PP).</td>
		</tr>
	</tbody>
</table>

fabrication of spherical and worm-shaped micellar nanocrystals by combining electrospray, self-assembly, and solvent-based structure control

胶束纳米晶 (胶束与封装纳米晶) 已成为一个新兴的主要类的 nanobiomaterials。本文介绍了一种基于自顶向下的电喷雾, 自下而上的自我装配和溶剂型结构控制的胶束纳米晶制备方法。该方法首先使用电喷雾产生均匀的超细液滴, 每一个都作为一个微型反应器, 在其中产生自组装反应形成胶束纳米晶, 与结构 (胶束形状和纳米晶封装) 由使用的有机溶剂控制。该方法在很大程度上是连续的, 生产高质量的胶束纳米晶产品, 结构控制方法低廉。利用水溶性有机溶剂四氢呋喃 (THF), 可以产生由溶剂诱导/促进胶束融合的蜗杆状胶束纳米晶。与普通球形胶束纳米晶相比, 蜗杆状胶束纳米晶能提供最小的非特异细胞吸收, 从而增强生物靶向性。通过将多个纳米晶共同封装到每个胶束中, 可以实现多功能或协同效应。目前这种制造方法的局限性将成为未来工作的一部分, 主要包括胶束纳米晶产品中的不完美封装和过程的不完全连续性质。

图 1显示了一个示意图, 概述了生产过程中使用的有机溶剂对胶束纳米晶的结构 (形状和封装) 的控制。简单地, 二氯甲烷导致球形胶束不封装纳米晶;氯仿导致球形胶束与低封装数量的纳米晶;THF 在短反应时间和蜗杆状胶束中, 在较长的反应时间内, 具有高封装数纳米晶的球形胶束。
用氯仿作为有机溶剂产生球形形状的胶束纳米晶, 其粒径为35纳米 (透射电镜);图 3a)。确保生产成功的关键质量控制方法是使用泰勒锥: 在 5–9 kV 范围内调整电压, 直到形成凹锥射流 (泰勒锥), 从而确保 "微型反应堆" 的形成, 其中自组装发生反应 "(图 3a)。相比之下,图 3b显示了当泰勒锥未正确形成时, 喷嘴尖端液流的外观和产品的 TEM 图像的照片。
以水相混 THF 为有机溶剂, 产生了类似蠕虫胶束的形状。THF 可以诱导/促进球形胶束的融合, 形成类似蠕虫形状 (图 4)13。图 4a、图 4b和图 4c分别以30分钟、60分钟和90分钟的生产时间显示产品的 TEM 图像。在图 4中可以看到, 增加的生产时间会导致越来越多的蠕虫形状的胶束纳米晶, 而90分钟几乎所有的胶束纳米晶都呈蠕虫状。此外, 用 THF 作为有机溶剂, 也增强了胶束中的纳米晶封装。
<img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/56657/56657fig1.jpg"> 图 1: 胶束纳米晶的生产过程示意图, 它结合了自上而下的电喷雾、自下而上的自组装和基于溶剂的结构控制.使用二氯甲烷导致空球形胶束 (不封装纳米晶的球形胶束);使用氯仿导致的球形胶束的低封装数量的纳米晶;利用 THF, 在短反应时间和蜗杆状胶束中, 具有高封装数的纳米晶团, 在很长的反应时间分别具有高封装纳米晶的球形胶束。此数字已从丁et修改。13<a href="//cloudflare-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/56657/56657fig1large.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/56657/56657fig2.jpg"> 图 2: 胶束纳米晶的制造装置示意图.该示意图显示了同轴电喷雾系统的总体设置, 主要由四部分组成: 1) 同轴喷嘴和钢圈, 2) 玻璃收集皿, 3) 注射器泵 A 和注射器泵 B, 和 4) 高压电源。1) 电喷雾同轴喷嘴尖端放置约0.8 厘米以上的接地钢环。2) 玻璃收集盘放在同轴喷嘴下面约10厘米。3) 在注射器泵 a 上, 注射器 a 连接到使用聚四氟乙烯管的电喷雾同轴喷嘴的内不锈钢毛细管中, 以应用半导体溶液和 PS PEG 溶液。在注射器泵 b, 注射器 b 连接到外部不锈钢毛细管的电喷雾同轴喷嘴使用 PTFE 管, 以应用 PVA 溶液。4) 电源正端 (红线) 连接到同轴喷嘴的内针, 而地线 (黑线) 连接到接地钢环, 电压范围从 + 5-9 伏。<a href="//cloudflare-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/56657/56657fig2large.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/56657/56657fig3.jpg"> 图 3: 结合电喷雾、自组装和氯仿作为有机溶剂产生的球形胶束纳米晶, 在同轴喷嘴尖端形成适当的泰勒锥, 作为关键质量控制方法.(a) 产品在成功生产过程后的 TEM 图像。嵌入: 在同轴喷嘴尖端形成的泰勒锥。(b) 产品在生产过程失败后的 TEM 图像。嵌入: 在同轴喷嘴尖端出现不正确形成的泰勒锥。此数字已从丁et修改。13<a href="//cloudflare-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/56657/56657fig3large.jpg" target="_blank">请单击此处查看此图的较大版本.</a>
<img alt="Figure 4" class="xfigimg" src="/files/ftp_upload/56657/56657fig4.jpg"> 图 4: 结合电喷雾、自组装和 THF 作为有机溶剂产生的类似蠕虫形状的胶束纳米晶.(a) 透射电镜产品在反应后30分钟 (b) tem 图像的产品反应后60分钟 (c) tem 图像的产品反应后90分钟 (d) 示意图显示形成机制THF 蜗杆状胶束。此数字已从丁et中复制。13<a href="//cloudflare-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/56657/56657fig4large.jpg" target="_blank">请单击此处查看此图的较大版本.</a>

Watch this Scientific Journal Video about Fabrication of Spherical and Worm-shaped Micellar Nanocrystals by Combining Electrospray, Self-assembly, and Solvent-based Structure Control at JoVE.com

Fabrication of Spherical and Worm-shaped Micellar Nanocrystals by Combining Electrospray, Self-assembly, and Solvent-based Structure Control

目前的工作描述了一种制造胶束纳米晶的方法, 这是一个新兴的 nanobiomaterials 类。该方法结合自顶向下的电喷雾, 自下而上的自我装配和溶剂型结构控制。制造方法主要是连续的, 能生产出高质量的产品, 并具有低廉的结构控制手段。

结合电喷雾、自组装和溶剂型结构控制制备球形和蜗杆状胶束纳米晶

Micellar nanocrystals (micelles with encapsulated nanocrystals) have become an emerging major class of nanobiomaterials. We describe a method of ...

fabrication-spherical-worm-shaped-micellar-nanocrystals-combining

Nanyang Technological University

Research

JoVE Journal

Chemistry

9.4K 次观看.  Nanjing University. 目前的工作描述了一种制造胶束纳米晶的方法, 这是一个新兴的 nanobiomaterials 类。该方法结合自顶向下的电喷雾, 自下而上的自我装配和溶剂型结构控制。制造方法主要是连续的, 能生产出高质量的产品, 并具有低廉的结构控制手段。

视频: Fabrication of Spherical and Worm-shaped Micellar Nanocrystals by Combining Electrospray, Self-assembly, and Solvent-based Structure Control

Origami Inspired Self-assembly of Patterned and Reconfigurable Particles

There are numerous techniques such as photolithography, electron-beam lithography and soft-lithography that can be used to precisely pattern two dimensional (2D) structures. These technologies are mature, offer high precision and many of them can be implemented in a high-throughput manner. We leverage the advantages of planar lithography and combine them with self-folding methods1-20 wherein physical forces derived from surface tension or residual stress, are used to curve or fold planar structures into three dimensional (3D) structures. In doing so, we make it possible to mass produce precisely patterned static and reconfigurable particles that are challenging to synthesize.
In this paper, we detail visualized experimental protocols to create patterned particles, notably, (a) permanently bonded, hollow, polyhedra that self-assemble and self-seal due to the minimization of surface energy of liquefied hinges21-23 and (b) grippers that self-fold due to residual stress powered hinges24,25. The specific protocol described can be used to create particles with overall sizes ranging from the micrometer to the centimeter length scales. Further, arbitrary patterns can be defined on the surfaces of the particles of importance in colloidal science, electronics, optics and medicine. More generally, the concept of self-assembling mechanically rigid particles with self-sealing hinges is applicable, with some process modifications, to the creation of particles at even smaller, 100 nm length scales22, 26 and with a range of materials including metals21, semiconductors9 and polymers27. With respect to residual stress powered actuation of reconfigurable grasping devices, our specific protocol utilizes chromium hinges of relevance to devices with sizes ranging from 100 &mu;m to 2.5 mm. However, more generally, the concept of such tether-free residual stress powered actuation can be used with alternate high-stress materials such as heteroepitaxially deposited semiconductor films5,7 to possibly create even smaller nanoscale grasping devices.

We describe experimental details of the synthesis of patterned and reconfigurable particles from two dimensional (2D) precursors. This methodology can be used to create particles in a variety of shapes including polyhedra and grasping devices at length scales ranging from the micro to centimeter scale.

折纸灵感的图案和可重构颗粒自组装

There are numerous techniques such as photolithography, electron-beam lithography and soft-lithography that can be used to precisely pattern two ...

科研

化学

Seeded Synthesis of CdSe/CdS Rod and Tetrapod Nanocrystals

We demonstrate a method for the synthesis of multicomponent nanostructures consisting of CdS and CdSe with rod and tetrapod morphologies. A seeded synthesis strategy is used in which spherical seeds of CdSe are prepared first using a hot-injection technique. By controlling the crystal structure of the seed to be either wurtzite or zinc-blende, the subsequent hot-injection growth of CdS off of the seed results in either a rod-shaped or tetrapod-shaped nanocrystal, respectively. The phase and morphology of the synthesized nanocrystals are confirmed using X-ray diffraction and transmission electron microscopy, demonstrating that the nanocrystals are phase-pure and have a consistent morphology. The extinction coefficient and quantum yield of the synthesized nanocrystals are calculated using UV-Vis absorption spectroscopy and photoluminescence spectroscopy. The rods and tetrapods exhibit extinction coefficients and quantum yields that are higher than that of the bare seeds. This synthesis demonstrates the precise arrangement of materials that can be achieved at the nanoscale by using a seeded synthetic approach.

A protocol for the seeded synthesis of rod-shaped and tetrapod-shaped multicomponent nanostructures consisting of CdS and CdSe is presented.

硒化镉/硫化镉棒和纳米四脚合成种子

We demonstrate a method for the synthesis of multicomponent nanostructures consisting of CdS and CdSe with rod and tetrapod morphologies. A seeded ...

Formation of Ordered Biomolecular Structures by the Self-assembly of Short Peptides

In nature, complex functional structures are formed by the self-assembly of biomolecules under mild conditions. Understanding the forces that control self-assembly and mimicking this process in vitro will bring about major advances in the areas of materials science and nanotechnology. Among the available biological building blocks, peptides have several advantages as they present substantial diversity, their synthesis in large scale is straightforward, and they can easily be modified with biological and chemical entities1,2. Several classes of designed peptides such as cyclic peptides, amphiphile peptides and peptide-conjugates self-assemble into ordered structures in solution. Homoaromatic dipeptides, are a class of short self-assembled peptides that contain all the molecular information needed to form ordered structures such as nanotubes, spheres and fibrils3-8. A large variety of these peptides is commercially available.
This paper presents a procedure that leads to the formation of ordered structures by the self-assembly of homoaromatic peptides. The protocol requires only commercial reagents and basic laboratory equipment. In addition, the paper describes some of the methods available for the characterization of peptide-based assemblies. These methods include electron and atomic force microscopy and Fourier-Transform Infrared Spectroscopy (FT-IR). Moreover, the manuscript demonstrates the blending of peptides (coassembly) and the formation of a &#34;beads on a string&#34;-like structure by this process.9 The protocols presented here can be adapted to other classes of peptides or biological building blocks and can potentially lead to the discovery of new peptide-based structures and to better control of their assembly.

This paper describes the formation of highly ordered peptide-based structures by the spontaneous process of self-assembly. The method utilizes commercially available peptides and common lab equipment. This technique can be applied to a large variety of peptides and may lead to the discovery of new peptide-based assemblies.

生物分子有序结构由短肽的自组装形成

In nature, complex functional structures are formed by the self-assembly of biomolecules under mild conditions. Understanding the forces that control ...

Self-assembly of Complex Two-dimensional Shapes from Single-stranded DNA Tiles

Current methods in DNA nano-architecture have successfully engineered a variety of 2D and 3D structures using principles of self-assembly. In this article, we describe detailed protocols on how to fabricate sophisticated 2D shapes through the self-assembly of uniquely addressable single-stranded DNA tiles which act as molecular pixels on a molecular canvas. Each single-stranded tile (SST) is a 42-nucleotide DNA strand composed of four concatenated modular domains which bind to four neighbors during self-assembly. The molecular canvas is a rectangle structure self-assembled from SSTs. A prescribed complex 2D shape is formed by selecting the constituent molecular pixels (SSTs) from a 310-pixel molecular canvas and then subjecting the corresponding strands to one-pot annealing. Due to the modular nature of the SST approach we demonstrate the scalability, versatility and robustness of this method. Compared with alternative methods, the SST method enables a wider selection of information polymers and sequences through the use of de novo designed and synthesized short DNA strands.

DNA tiling is an effective approach to make programmable nanostructures. We describe the protocols to construct complex two-dimensional shapes by the self-assembly of single-stranded DNA tiles.

复杂的二维形状的从单链DNA的瓷砖自组装

Current methods in DNA nano-architecture have successfully engineered a variety of 2D and 3D structures using principles of self-assembly. In this ...

A Study of the Complexation of Mercury(II) with Dicysteinyl Tetrapeptides by Electrospray Ionization Mass Spectrometry

In this study we evaluated a method for the characterization of complexes, formed in different relative ratios of mercury(II) to dicysteinyl tetrapeptide, by electrospray ionization orbitrap mass spectrometry. This strategy is based on previous successful characterization of mercury-dicysteinyl complexes involving tripeptides by utilizing mass spectrometry among other techniques. Mercury(II) chloride and a dicysteinyl tetrapeptide were incubated in a degassed buffered medium at varying stoichiometric ratios. The complexes formed were subsequently analyzed on an electrospray mass spectrometer consisting of a hybrid linear ion- and orbi- trap mass analyzer. The electrospray ionization mass spectrometry (ESI-MS) spectra were acquired in the positive mode and the observed peaks were then analyzed for distinct mercury isotopic distribution patterns and associated monoisotopic peak. This work demonstrates that an accurate stoichiometry of mercury and peptide in the complexes formed under specified electrospray ionization conditions can be determined by using high resolution ESI MS based on distinct mercury isotopic distribution patterns.

A Study of the Complexation of MercuryII with Dicysteinyl Tetrapeptides by Electrospray Ionization Mass Spectrometry

The characterization of complexes formed in different relative ratios of mercury(II) to dicysteinyl tetrapeptides by electrospray ionization orbitrap mass spectrometry is presented.

汞（II）与Dicysteinyl四肽的络合的电喷雾质​​谱研究

In this study we evaluated a method for the characterization of complexes, formed in different relative ratios of mercury(II) to dicysteinyl tetrapeptide, ...

Influence of Hybrid Perovskite Fabrication Methods on Film Formation, Electronic Structure, and Solar Cell Performance

Hybrid organic/inorganic halide perovskites have lately been a topic of great interest in the field of solar cell applications, with the potential to achieve device efficiencies exceeding other thin film device technologies. Yet, large variations in device efficiency and basic physical properties are reported. This is due to unintentional variations during film processing, which have not been sufficiently investigated so far. We therefore conducted an extensive study of the morphology and electronic structure of a large number of CH3NH3PbI3 perovskite where we show how the preparation method as well as the mixing ratio of educts methylammonium iodide and lead(II) iodide impact properties like film formation, crystal structure, density of states, energy levels, and ultimately the solar cell performance.

We present an extensive study on the effects of different fabrication methods for organic/inorganic perovskite thin films by comparing crystal structures, density of states, energy levels, and ultimately the solar cell performance.

上成膜钙钛矿型混合制造方法，电子结构和太阳能电池性能的影响

Hybrid organic/inorganic halide perovskites have lately been a topic of great interest in the field of solar cell applications, with the potential to ...

Fabrication and Testing of Photonic Thermometers

In recent years, a push for developing novel silicon photonic devices for telecommunications has generated a vast knowledge base that is now being leveraged for developing sophisticated photonic sensors. Silicon photonic sensors seek to exploit the strong confinement of light in nano-waveguides to transduce changes in physical state to changes in resonance frequency. In the case of thermometry, the thermo-optic coefficient, i.e., changes in refractive index due to temperature, causes the resonant frequency of the photonic device such as a Bragg grating to drift with temperature. We are developing a suite of photonic devices that leverage recent advances in telecom compatible light sources to fabricate cost-effective photonic temperature sensors, which can be deployed in a wide variety of settings ranging from controlled laboratory conditions, to the noisy environment of a factory floor or a residence. In this manuscript, we detail our protocol for the fabrication and testing of photonic thermometers.

We describe the process of fabrication and testing of photonic thermometers.

光子温度计的制作与测试

In recent years, a push for developing novel silicon photonic devices for telecommunications has generated a vast knowledge base that is now being ...

Grafting Multiwalled Carbon Nanotubes with Polystyrene to Enable Self-Assembly and Anisotropic Patchiness

We demonstrate a straightforward protocol to graft pristine multiwalled carbon nanotubes (MWCNTs) with polystyrene (PS) chains at the sidewalls through a free-radical polymerization strategy to enable the modulation of the nanotube surface properties and produce supramolecular self-assembly of the nanostructures. First, a selective hydroxylation of the pristine nanotubes through a biphasic catalytically mediated oxidation reaction creates superficially distributed reactive sites at the sidewalls. The latter reactive sites are subsequently modified with methacrylic moieties using a silylated methacrylic precursor to create polymerizable sites. Those polymerizable groups can address further polymerization of styrene to produce a hybrid nanomaterial containing PS chains grafted to the nanotube sidewalls. The polymer-graft content, amount of silylated methacrylic moieties introduced and hydroxylation modification of the nanotubes are identified and quantified by Thermogravimetric Analysis (TGA). The presence of reactive functional groups hydroxyl and silylated methacrylate are confirmed by Fourier Transform Infrared Spectroscopy (FT-IR). Polystyrene-grafted carbon nanotube solutions in tetrahydrofuran (THF) provide wall-to-wall collinearly self-assembled nanotubes when cast samples are analyzed by transmission electron microscopy (TEM). Those self-assemblies are not obtained when suitable blanks are similarly cast from analogous solutions containing non-grafted counterparts. Therefore, this method enables the modification of the nanotube anisotropic patchiness at the sidewalls which results into spontaneous auto-organization at the nanoscale.

A procedure for the synthesis of polystyrene-grafted multiwalled carbon nanotubes using successive chemical modification steps to selectively introduce the polymer chains to the sidewalls and their self-assembly via anisotropic patchiness is presented.

用聚苯乙烯接枝多壁纳米碳纳米管使自组装和各向异性斑块

We demonstrate a straightforward protocol to graft pristine multiwalled carbon nanotubes (MWCNTs) with polystyrene (PS) chains at the sidewalls through a ...

Liquid-cell Transmission Electron Microscopy for Tracking Self-assembly of Nanoparticles

Drying a nanoparticle dispersion is a versatile way to create self-assembled structures of nanoparticles, but the mechanism of this process is not fully understood. We have traced the trajectories of individual nanoparticles using liquid-cell transmission electron microscopy (TEM) to investigate the mechanism of the assembly process. Herein, we present the protocols used for liquid-cell TEM studies of the self-assembly mechanism. First, we introduce the detailed synthetic protocols used to produce uniformly sized platinum and lead selenide nanoparticles. Next, we present the microfabrication processes used to produce liquid cells with silicon nitride or silicon windows and then describe the loading and imaging procedures of the liquid-cell TEM technique. Several notes are included to provide helpful tips for the entire process, including how to manage the fragile cell windows. The individual motions of nanoparticles tracked by liquid-cell TEM revealed that changes in the solvent boundaries caused by evaporation affected the self-assembly process of nanoparticles. The solvent boundaries drove nanoparticles to primarily form amorphous aggregates, followed by flattening of the aggregates to produce a 2-dimensional (2D) self-assembled structure. These behaviors are also observed for different nanoparticle types and different liquid-cell compositions.

Here we introduce experimental protocols for the real-time observation of a self-assembly process using liquid-cell transmission electron microscopy.

用于跟踪纳米粒子自组装的液体细胞透射电子显微镜

Drying a nanoparticle dispersion is a versatile way to create self-assembled structures of nanoparticles, but the mechanism of this process is not fully ...

Synthesis of Core-shell Lanthanide-doped Upconversion Nanocrystals for Cellular Applications

Lanthanide-doped upconversion nanocrystals (UCNs) have attracted much attention in recent years based on their promising and controllable optical properties, which allow for the absorption of near-infrared (NIR) light and can subsequently convert it into multiplexed emissions that span over a broad range of regions from the UV to the visible to the NIR. This article presents detailed experimental procedures for high-temperature co-precipitation synthesis of core-shell UCNs that incorporate different lanthanide ions into nanocrystals for efficiently converting deep-tissue penetrable NIR excitation (808 nm) into a strong blue emission at 480 nm. By controlling the surface modification with biocompatible polymer (polyacrylic acid, PAA), the as-prepared UCNs acquires great solubility in buffer solutions. The hydrophilic nanocrystals are further functionalized with specific ligands (dibenzyl cyclooctyne, DBCO) for localization on the cell membrane. Upon NIR light (808 nm) irradiation, the upconverted blue emission can effectively activate the light-gated channel protein on the cell membrane and specifically regulate the cation (e.g., Ca2+) influx in the cytoplasm. This protocol provides a feasible methodology for the synthesis of core-shell lanthanide-doped UCNs and subsequent biocompatible surface modification for further cellular applications.

A protocol is presented for the synthesis of core-shell lanthanide-doped upconversion nanocrystals (UCNs) and their cellular applications for channel protein regulation upon near-infrared (NIR) light illumination.