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...

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&amp;ndash;23 kDa, 87&amp;ndash;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&amp;ndash;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 &amp;mu;m; inner diameter 300 &amp;mu;m). Outer capillary was a 20 gauge (outer diameter 1,000 &amp;mu;m; inner diameter 500 &amp;mu;m).</td></tr><tr><td>Vortexer</td><td>Xi&#039;an HEB Biotechnology Co., Ltd. China</td><td>MX-S</td><td>MX-S with wide speed range of 0&amp;ndash;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&amp;ndash;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...

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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

Research

JoVE Journal

Chemistry

10.3K 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

Controlling the Size, Shape and Stability of Supramolecular Polymers in Water

For aqueous based supramolecular polymers, the simultaneous control over shape, size and stability is very difficult1. At the same time, the ability to do so is highly important in view of a number of applications in functional soft matter including electronics, biomedical engineering, and sensors. In the past, successful strategies to control the size and shape of supramolecular polymers typically focused on the use of templates2,3, end cappers4 or selective solvent techniques5. 
Here we disclose a strategy based on self-assembling discotic amphiphiles that leads to the control over stack length and shape of ordered, chiral columnar aggregates. By balancing electrostatic repulsive interactions on the hydrophilic rim and attractive non-covalent forces within the hydrophobic core of the polymerizing building block, we manage to create small and discrete spherical objects6,7. Increasing the salt concentration to screen the charges induces a sphere-to-rod transition. Intriguingly, this transition is expressed in an increase of cooperativity in the temperature-dependent self-assembly mechanism, and more stable aggregates are obtained. 
For our study we select a benzene-1,3,5-tricarboxamide (BTA) core connected to a hydrophilic metal chelate via a hydrophobic, fluorinated L-phenylalanine based spacer (Scheme 1). The metal chelate selected is a Gd(III)-DTPA complex that contains two overall remaining charges per complex and necessarily two counter ions. The one-dimensional growth of the aggregate is directed by &pi;-&pi; stacking and intermolecular hydrogen bonding. However, the electrostatic, repulsive forces that arise from the charges on the Gd(III)-DTPA complex start limiting the one-dimensional growth of the BTA-based discotic once a certain size is reached. At millimolar concentrations the formed aggregate has a spherical shape and a diameter of around 5 nm as inferred from 1H-NMR spectroscopy, small angle X-ray scattering, and cryogenic transmission electron microscopy (cryo-TEM). The strength of the electrostatic repulsive interactions between molecules can be reduced by increasing the salt concentration of the buffered solutions. This screening of the charges induces a transition from spherical aggregates into elongated rods with a length &gt; 25 nm. Cryo-TEM allows to visualise the changes in shape and size. In addition, CD spectroscopy permits to derive the mechanistic details of the self-assembly processes before and after the addition of salt. Importantly, the cooperativity -a key feature that dictates the physical properties of the produced supramolecular polymers- increases dramatically upon screening the electrostatic interactions. This increase in cooperativity results in a significant increase in the molecular weight of the formed supramolecular polymers in water.

The goal of this experiment is to determine and control the size, shape and stability of self-assembled discotic amphiphiles in water. For aqueous based supramolecular polymers such level of control is very difficult. We apply a strategy using both repulsive and attractive interactions. The experimental techniques applied to characterize this system are broadly applicable.

控制的大小，形状和稳定性超分子聚合物在水

For aqueous based supramolecular polymers, the simultaneous control over shape, size and stability is very difficult1. At the same time, the ability to do ...

科研

工程学

A Technique to Functionalize and Self-assemble Macroscopic Nanoparticle-ligand Monolayer Films onto Template-free Substrates

This protocol describes a self-assembly technique to create macroscopic monolayer films composed of ligand-coated nanoparticles1,2. The simple, robust and scalable technique efficiently functionalizes metallic nanoparticles with thiol-ligands in a miscible water/organic solvent mixture allowing for rapid grafting of thiol groups onto the gold nanoparticle surface. The hydrophobic ligands on the nanoparticles then quickly phase separate the nanoparticles from the aqueous based suspension and confine them to the air-fluid interface. This drives the ligand-capped nanoparticles to form monolayer domains at the air-fluid interface.&#160; The use of water-miscible organic solvents is important as it enables the transport of the nanoparticles from the interface onto template-free substrates.&#160; The flow is mediated by a surface tension gradient3,4 and creates macroscopic, high-density, monolayer nanoparticle-ligand films.&#160; This self-assembly technique may be generalized to include the use of particles of different compositions, size, and shape and may lead to an efficient assembly method to produce low-cost, macroscopic, high-density, monolayer nanoparticle films for wide-spread applications.

A simple, robust and scalable technique to functionalize and self-assemble macroscopic nanoparticle-ligand monolayer films onto template-free substrates is described in this protocol.

一种技术，功能化和自组装纳米宏观 - 配体单层膜模板上无基材

This protocol describes a self-assembly technique to create macroscopic monolayer films composed of ligand-coated nanoparticles1,2. The simple, robust and ...

化学

Facile Synthesis of Worm-like Micelles by Visible Light Mediated Dispersion Polymerization Using Photoredox Catalyst

Presented herein is a protocol for the facile synthesis of worm-like micelles by visible light mediated dispersion polymerization. This approach begins with the synthesis of a hydrophilic poly(oligo(ethylene glycol) methyl ether methacrylate) (POEGMA) homopolymer using reversible addition-fragmentation chain-transfer (RAFT) polymerization. Under mild visible light irradiation (&#955; = 460 nm, 0.7 mW/cm2), this macro-chain transfer agent (macro-CTA) in the presence of a ruthenium based photoredox catalyst, Ru(bpy)3Cl2 can be chain extended with a second monomer to form a well-defined block copolymer in a process known as Photoinduced Electron Transfer RAFT (PET-RAFT). When PET-RAFT is used to chain extend POEGMA with benzyl methacrylate (BzMA) in ethanol (EtOH), polymeric nanoparticles with different morphologies are formed in situ according to a polymerization-induced self-assembly (PISA) mechanism. Self-assembly into nanoparticles presenting POEGMA chains at the corona and poly(benzyl methacrylate) (PBzMA) chains in the core occurs in situ due to the growing insolubility of the PBzMA block in ethanol. Interestingly, the formation of highly pure worm-like micelles can be readily monitored by observing the onset of a highly viscous gel in situ due to nanoparticle entanglements occurring during the polymerization. This process thereby allows for a more reproducible synthesis of worm-like micelles simply by monitoring the solution viscosity during the course of the polymerization. In addition, the light stimulus can be intermittently applied in an ON/OFF manner demonstrating temporal control over the nanoparticle morphology.

This article describes a process for producing polymeric self-assembled nanoparticles using visible light mediated dispersion polymerization. Using low energy visible light to control the polymerization allows for the reproducible formation of self-assembled worm-like micelles at high solids content.

使用Photoredox催化剂蠕虫状胶束的简便合成可见光介导的分散聚合

Presented herein is a protocol for the facile synthesis of worm-like micelles by visible light mediated dispersion polymerization. This approach begins ...

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 ...

Fabrication of Polymer Microspheres for Optical Resonator and Laser Applications

This paper describes three methods of preparing fluorescent microspheres comprising &#960;-conjugated or non-conjugated polymers: vapor diffusion, interface precipitation, and mini-emulsion. In all methods, well-defined, micrometer-sized spheres are obtained from a self-assembling process in solution. The vapor diffusion method can result in spheres with the highest sphericity and surface smoothness, yet the types of the polymers able to form these spheres are limited. On the other hand, in the mini-emulsion method, microspheres can be made from various types of polymers, even from highly crystalline polymers with coplanar, &#960;-conjugated backbones. The photoluminescent (PL) properties from single isolated microspheres are unusual: the PL is confined inside the spheres, propagates at the circumference of the spheres via the total internal reflection at the polymer/air interface, and self-interferes to show sharp and periodic resonant PL lines. These resonating modes are so-called "whispering gallery modes" (WGMs). This work demonstrates how to measure WGM PL from single isolated spheres using the micro-photoluminescence (&#181;-PL) technique. In this technique, a focused laser beam irradiates a single microsphere, and the luminescence is detected by a spectrometer. A micromanipulation technique is then used to connect the microspheres one by one and to demonstrate the intersphere PL propagation and color conversion from coupled microspheres upon excitation at the perimeter of one sphere and detection of PL from the other microsphere. These techniques, &#181;-PL and micromanipulation, are useful for experiments on micro-optic application using polymer materials.

Protocols for the synthesis of microspheres from polymers, the manipulation of microspheres, and micro-photoluminescence measurements are presented.

用于光学谐振器和激光应用的聚合物微球的制造

This paper describes three methods of preparing fluorescent microspheres comprising &#960;-conjugated or non-conjugated polymers: vapor diffusion, ...

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 ...

Synthesis of Monodisperse Cylindrical Nanoparticles via Crystallization-driven Self-assembly of Biodegradable Block Copolymers

The production of monodisperse cylindrical micelles is a significant challenge in polymer chemistry. Most cylindrical constructs formed from diblock copolymers are produced by one of three techniques: thin film rehydration, solvent switching or polymerization-induced self-assembly, and produce only flexible, polydisperse cylinders. Crystallization-driven self-assembly (CDSA) is a method which can produce cylinders with these properties, by stabilizing structures of a lower curvature due to the formation of a crystalline core. However, the living polymerization techniques by which most core-forming blocks are formed are not trivial processes and the CDSA process may yield unsatisfactory results if carried out incorrectly. Here, the synthesis of cylindrical nanoparticles from simple reagents is shown. The drying and purification of reagents prior to a ring-opening polymerization of &#949;-caprolactone catalyzed by diphenyl phosphate is described. This polymer is then chain extended by methyl methacrylate (MMA) followed by N,N-dimethyl acrylamide (DMA) using reversible addition&#8722;fragmentation chain-transfer (RAFT) polymerization, affording a triblock copolymer that can undergo CDSA in ethanol. The living CDSA process is outlined, the results of which yield cylindrical nanoparticles up to 500 nm in length and a length dispersity as low as 1.05. It is anticipated that these protocols will allow others to produce cylindrical nanostructures and elevate the field of CDSA in the future.

Crystallization-driven self-assembly (CDSA) displays the unique ability to fabricate cylindrical nanostructures of narrow length distributions. The organocatalyzed ring-opening polymerization of &#949;-caprolactone and subsequent chain extensions of methyl methacrylate and N,N-dimethyl acrylamide are demonstrated. A living CDSA protocol that produces monodisperse cylinders up to 500 nm in length is outlined.

通过结晶驱动生物降解块共聚物的自组装合成单分散圆柱状纳米粒子

The production of monodisperse cylindrical micelles is a significant challenge in polymer chemistry. Most cylindrical constructs formed from diblock ...

Assembly and Characterization of Polyelectrolyte Complex Micelles

Polyelectrolyte complex micelles (PCMs), core-shell nanoparticles formed by self-assembly of charged polymers in aqueous solution, provide a powerful platform for exploring the physics of polyelectrolyte interactions and also offer a promising solution to the pressing problem of delivering therapeutic oligonucleotides in vivo. Developing predictive structure-property relationships for PCMs has proven difficult, in part due to the presence of strong kinetic traps during nanoparticle self-assembly. This article discusses criteria for choosing polymers for PCM construction and provides protocols based on salt annealing that enable assembly of repeatable, low-polydispersity nanoparticles. We also discuss PCM characterization using light scattering, small-angle X-ray scattering, and electron microscopy.

We provide protocols and representative data for designing, assembling, and characterizing polyelectrolyte complex micelles, core-shell nanoparticles formed by polyelectrolytes and hydrophilic charged-uncharged block copolymers.

聚电解质复合微晶体的组装与特性

Polyelectrolyte complex micelles (PCMs), core-shell nanoparticles formed by self-assembly of charged polymers in aqueous solution, provide a powerful ...

Fabrication of Zero Mode Waveguides for High Concentration Single Molecule Microscopy

In single molecule fluorescence enzymology, background fluorescence from labeled substrates in solution often limits fluorophore concentration to pico- to nanomolar ranges, several orders of magnitude less than many physiological ligand concentrations. Optical nanostructures called zero mode waveguides (ZMWs), which are 100&#8722;200 nm in diameter apertures fabricated in a thin conducting metal such as aluminum or gold, allow imaging of individual molecules at micromolar concentrations of fluorophores by confining visible light excitation to zeptoliter effective volumes. However, the need for expensive and specialized nanofabrication equipment has precluded the widespread use of ZMWs. Typically, nanostructures such as ZMWs are obtained by direct writing using electron beam lithography, which is sequential and slow. Here, colloidal, or nanosphere, lithography is used as an alternative strategy to create nanometer-scale masks for waveguide fabrication. This report describes the approach in detail, with practical considerations for each phase. The method allows thousands of aluminum or gold ZMWs to be made in parallel, with final waveguide diameters and depths of 100&#8722;200 nm. Only common lab equipment and a thermal evaporator for metal deposition are required. By making ZMWs more accessible to the biochemical community, this method can facilitate the study of molecular processes at cellular concentrations and rates.

Described here is a nanosphere lithography method for parallel fabrication of zero mode waveguides, which are arrays of nanoapertures in a metal-clad glass microscopy coverslip for single molecule imaging at nano- to micromolar concentrations of fluorophores. The method takes advantage of colloidal crystal self-assembly to create a waveguide template.

为高浓度单分子显微镜制造零模式波导

In single molecule fluorescence enzymology, background fluorescence from labeled substrates in solution often limits fluorophore concentration to pico- to ...

生物工程

开发用于生物医学的海藻酸钠水凝胶微球

Preparation of Cross-Linked Sodium Alginate Microspheres with Different Metal Ions Using the Microfluidic Electrospray Technology

Microspheres are micrometer-sized particles that can load and gradually release drugs via physical encapsulation or adsorption onto the surface and within polymers. In the field of biomedicine, hydrogel microspheres have been extensively studied for their application as drug carriers owing to their ability to reduce the frequency of drug administration, minimize side effects, and improve patient compliance. Sodium alginate (ALG) is a naturally occurring linear polysaccharide with three backbone glycosidic linkages. There are two auxiliary hydroxyl groups present in each of the moieties of the polymer, which have the characteristics of an alcohol hydroxyl moiety. The synthetic ALG units can undergo chemical cross-linking reactions with metal ions, forming a cross-linked network structure of polymer stacks, ultimately forming a hydrogel. Hydrogel microspheres can be prepared using a simple process involving the ionic cross-linking properties of ALG. In this study, we prepared ALG-based hydrogel microspheres (ALGMS) using a microfluidic electrodeposition strategy. The prepared hydrogel microspheres were uniformly sized and well-dispersed, owing to accurate control of the microfluidic electrospray flow. ALGMS cross-linked with different metal ions were prepared using a microfluidic electrospray technique combining microfluidic and high electric field, and its antimicrobial properties, slow drug release ability, and biocompatibility were investigated. This technology holds promise for application in advanced drug development and production.

作者聚焦：使用生物相容性海藻酸钠水凝胶微球推进治疗

The protocol describes the preparation of sodium alginate microspheres cross-linked with different metal ions using a microfluidic device for drug carrier design. The antimicrobial properties and slow drug release of these microspheres were also investigated.

利用微流控电喷雾技术制备具有不同金属离子的交联海藻酸钠微球

Microspheres are micrometer-sized particles that can load and gradually release drugs via physical encapsulation or adsorption onto the surface and within ...