Name: preparation of hollow polystyrene particles and microcapsules by radical polymerization of janus droplets consisting of hydrocarbon and fluorocarbon oils
Uploaded: 2018-01-25T13:30:00.000+00:00
Duration: 7 min 1 s
Description: Watch this Scientific Journal Video about Preparation of Hollow Polystyrene Particles and Microcapsules by Radical Polymerization of Janus Droplets Consisting of Hydrocarbon and Fluorocarbon Oils at J

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1. 制备由苯乙烯/PFO/水溶液混合液组成的乳液
<ol><li>为制备5毫米的水 sds 溶液, 在高纯度 H2O 10 毫升中溶解14.5 毫克 sds。 注: 高纯度 H2O 已被使用 (电阻率 (R) = 18 ω cm, 表面张力 (γ) = 72.0 mN m-1在25° c)。</li>
	<li>加入1.5 克苯乙烯, 0.6 克 PFO, 0.9 克5毫米的水溶液 SDS 溶液到10毫升玻璃小瓶与搅拌棒。 注: 在扫描共聚焦荧光显微镜观察, 添加2.6 毫克香豆素102和0.062 毫克的素的混合物。</li>
	<li>在室温下搅动60分钟 1150 rpm 的混合物, 然后将温度升高到80° c。</li>
	<li>搅拌的混合物为60分钟, 在 1150 rpm 和80° c。</li>
</ol>2. 用苯乙烯/PFO/水溶液混合物组成的乳液制备聚合物微粒
<ol><li>添加3.9 毫克的钾硫酸钾, 2 毫克的芘, 1.5 克苯乙烯, 0.6 克 PFO, 0.9 克5毫米的水溶液 SDS 溶液到10毫升玻璃小瓶与搅拌棒和密封它与橡胶隔膜。</li>
	<li>通过注射器针将氮气 Deoxygenate 30 分钟。 注意: 缓慢流动的氮气不会产生大量的泡沫。</li>
	<li>准备乳液, 搅拌60分钟的混合物在 1150 rpm 和室温, 然后提高温度到80° c。</li>
	<li>搅拌的混合物为30分钟, 在 1150 rpm 和80° c。</li>
	<li>将所产生的溶液 (3 毫升) 中的多云部分 (1.8 毫升) 转移到试管中, 然后加入30% 乙醇溶液以完全终止聚合反应。</li>
	<li>几种 (功率: 130 W, 频率: 4.2 赫), 10 分钟洗涤产生的聚合物粒子, 然后离心10分钟, 在 2300 x g。</li>
	<li>要获得聚合物粒子, 从试管中除去上清溶液。</li>
	<li>在试管中加入3毫升的水到所产生的固体中。几种 (功率: 130 W, 频率: 4.2 赫) 为10分钟和离心机为 10 min 在 2300 x g. 从试管中取出上清液。</li>
	<li>重复洗涤过程 (步骤 2.8), 直到没有从上清溶液生成泡沫。蒸发水获得固体的空心高分子颗粒。</li>
</ol>3. 利用空心高分子微粒制备微胶囊
<ol><li>加入1毫克的空心聚苯乙烯颗粒 (步骤 2.9) 和4毫升的水到一个10毫升玻璃小瓶与搅拌棒。</li>
	<li>几种 (功率: 130 W, 频率: 4.2 赫), 用于在水中分散空心粒子10分钟。</li>
	<li>在室温下, 将0.1 毫升的甲苯添加到水中分散的颗粒, 然后搅拌1小时 100 rpm。将液体转移到试管。 注意: 如果每分钟的自转增加, 粒子的形态就会变形。</li>
	<li>离心液体为10分钟在 2300 x g 分离微囊形成它。从试管中取出上清液。</li>
</ol>

<ol>
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在水 SDS 浓度和苯乙烯、PFO 的重量分数的 10% 以上, 得到了含苯乙烯和 PFO 的乳液。当含有该液滴的乳液的各种重量分数被聚合为30分钟时, 可以获得所有成分的空心聚苯乙烯颗粒。这些结果表明, 此处所示的协议很简单。此外, 本文所述方法中的聚合时间可以控制空心聚苯乙烯颗粒的直径、孔径大小和孔体积。
我们建议以下的机制来制造空心聚苯乙烯颗粒。在80° c 的含水 SDS 溶液、苯乙烯和 PFO 混合物的 O/W 乳液中形成了由苯乙烯和 PFO 组成的两面油滴。PFO 液滴位于苯乙烯滴的表面。由于作为聚合的引发剂的科索沃警察部队在水相中是可溶的, 聚合将在苯乙烯/水溶液 SDS 溶液的界面上进行。在80° c 时, 三元乳液中苯乙烯聚合成聚苯乙烯, 而 PFO 没有聚合基团, 在该温度下仍留在乳液中。聚合终止后, 通过去除 PFO, 形成聚苯乙烯颗粒上的孔。因此, 在表面上有孔的中空杯状聚苯乙烯颗粒是任何苯乙烯和 PFO 的重量分数和所有聚合时间的产物。
在90分钟内, 将少量的甲苯加入到由自由基聚合制备的空心聚苯乙烯颗粒上, 就会使空心聚苯乙烯颗粒上的孔洞得到密封。这一现象与赫 al.9报告的是一致的。封装法可以在微粒中含有水的物质。
在本文中, 我们展示了一种使用由苯乙烯和 PFO 组成的含油滴的中空聚合物颗粒的制备方法, 它们是相互不相容的。非球形高分子颗粒的制备方法, 由于其在各种应用中的潜在用途, 已经得到了广泛的研究。该策略采用烃油和氟碳油的两面油滴, 适用于不同类型单体和药物输送系统的非球形聚合物颗粒的制备。

虽然球形高分子颗粒已广泛应用于各种工业应用, 但众所周知, 酒窝粒子, 半球, 磁盘, 和椭球, 已准备通过播种聚合1,2,3, 使用具有特定几何形状的微的非球形单体液滴的光聚合,4,5, 使用聚合物再的自组织6, 以及球形聚合物的变形微粒由机械外部力量7,8。特别是, 由溶剂9,10 , 用多乳剂聚合而成的球形高分子颗粒的好溶剂蒸发制备了微米级的中空聚合物颗粒。11,12。
在这项工作中, 我们关注的是烃类和氟碳油的相互溶在聚合物微粒的制造中的应用。混合表面活性剂在分子中有一个碳氢化合物链和一个氟碳链。此前, 我们报告了在常规表面活性剂中未观察到的混合表面活性剂的独特特性13,14,15。我们还研究了使用烃类油、氟碳油和表面活性剂溶液的乳液, 它们是相互不相容的16。然而, 对乳剂的研究很少有17。这些研究描述了由烃油和氟碳油组成的油滴在表面活性剂溶液中的形貌。
在这里, 我们展示了一个详细的协议制造空心聚合物颗粒的基础聚合使用油滴的乳液由烃油, 氟碳油, 和水钠硫酸钠 (SDS) 溶液。本文提出了一种新的非球形高分子颗粒制备方法, 它有别于常规的工艺。该方法能在短时间内简单地制备空心高分子颗粒。此外, 还显示了通过空心高分子微粒制备微胶囊的协议。

<table><tbody><tr><td>&lt;strong&gt;Material&lt;/strong&gt;</td><td></td><td></td><td></td></tr><tr><td>Sodium dodecylsulfate, 95.0%</td><td>Wako Pure Chemical Industries, Ltd.</td><td>192-08672</td><td></td></tr><tr><td>Styrene, 99.0%</td><td>Tokyo Chemical Industry Co. Ltd.</td><td>S0095</td><td></td></tr><tr><td>Perfluorooctane, 99%</td><td>Fluorochem Ltd.</td><td>8706</td><td></td></tr><tr><td>Coumarin 102, 97.0%</td><td>Tokyo Chemical Industry Co. Ltd.</td><td>C2267</td><td></td></tr><tr><td>Calcein</td><td>Dojindo Molecular Technologies, Inc.</td><td>C001</td><td></td></tr><tr><td>Potassium peroxodisulfate, 98.0%</td><td>Kanto Chemical Co., Inc.</td><td>32375-30</td><td></td></tr><tr><td>Pyrene, 97.0%</td><td>Wako Pure Chemical Industries, Ltd.</td><td>167-05302</td><td></td></tr><tr><td>Ethanol, 99.5%</td><td>Kanto Chemical Co., Inc.</td><td>14033-00</td><td></td></tr><tr><td>Toluene, 99.5%</td><td>Kanto Chemical Co., Inc.</td><td>40180-00</td><td></td></tr><tr><td>&lt;strong&gt;Name&lt;/strong&gt;</td><td>&lt;strong&gt;Company&lt;/strong&gt;</td><td>&lt;strong&gt;Catalog Number&lt;/strong&gt;</td><td>&lt;strong&gt;Comments&lt;/strong&gt;</td></tr><tr><td>&lt;strong&gt;Equipment&lt;/strong&gt;</td><td></td><td></td><td></td></tr><tr><td>Scanning Electron Microscope</td><td>Hitachi High-Technologies Corporation</td><td>S-4800</td><td></td></tr><tr><td>Scanning Transmission Electron Microscope</td><td>Hitachi High-Technologies Corporation</td><td>S-4800</td><td></td></tr><tr><td>Ultrasonic cleaner</td><td>Branson Ultrasonics, Emerson Japan, Ltd.</td><td>Model 3510</td><td></td></tr><tr><td>Centrifuge</td><td>AS ONE Corporation</td><td>CN-1050</td><td></td></tr></tbody></table>

preparation of hollow polystyrene particles and microcapsules by radical polymerization of janus droplets consisting of hydrocarbon and fluorocarbon oils

在这篇文章中, 我们已经演示了一种方法, 生产空心颗粒和微胶囊使用油滴由烃油 (苯乙烯) 和氟碳油 (氟-n-辛烷, PFO) 在水表面活性剂 (钠硫酸钠,SDS) 解决方案。由于氟碳油与烃类油不相容, 这两种油分离。乳液是由搅拌苯乙烯/PFO/水 SDS 溶液混合物在80° c。用光学显微镜和扫描共聚焦荧光显微镜观察了乳液的类型和液滴的形貌。结果表明, 在 SDS 溶液中形成了由相互不相容的苯乙烯和 PFO 组成的油滴。聚苯乙烯颗粒是由苯乙烯/PFO/水 SDS 溶液在80° c 的三元混合物的自由基聚合制备的。通过扫描电子显微镜和扫描透射电镜观察, 证实了聚苯乙烯的形貌。这些观察表明, 表面上有一个孔的聚苯乙烯空心颗粒的制备。根据我们的知识, 这种方法是一种新的战略使用溶烃和氟碳油。空心颗粒也可用于微胶囊的制备。

光和扫描共聚焦荧光显微镜观察, 以确定的形态和组成的液滴在乳液由苯乙烯, PFO, 和5毫米水溶液 SDS (图 1)。扫描电子显微镜 (SEM) 和扫描透射电镜 (词干) 观察显示空心粒子和微胶囊的形成 (图 2)。
由苯乙烯/PFO/水 sds 溶液三元混合物组成的乳剂的 DIC 和共聚焦荧光显微图像表明, 连续相是水 sds 溶液, 因为在素中观察到的绿色荧光连续相, 因此, 油内水型乳剂形成 (图 1a和1b)。这些图像还表明, 油滴包括苯乙烯和 PFO, 这是相互不相容的。含香豆素102乳剂的 DIC 和共焦荧光显微图像显示, PFO 液滴位于水与苯乙烯滴之间的界面上。苯乙烯、PFO 和水 SDS 溶液的三元混合物, 其5毫米的乳液含有由苯乙烯和 PFO 组成的两面油滴。
styrene/PFO/5 毫米水溶液的乳液自由基聚合制备的聚合物粒子的扫描电镜和干图表明, 表面有孔的空心非球形聚苯乙烯颗粒 (图 2a和2b). 通过扫描电镜和茎秆观察200粒子, 评价空心聚苯乙烯颗粒的形成速率、直径和孔径。平均直径估计从 SEM 观察是1.3 µm。尺寸与由动态光散射测量估计的聚合物颗粒的直径一致。形成率约为100%。空心颗粒中孔的平均孔径和体积分别为0.8 ±0.4 µm 和0.9 ±0.4 µm3。因此, 在乳液中含有苯乙烯的同液滴的自由基聚合, 制备出具有0.8 µm 孔的空心聚苯乙烯颗粒。
<img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/56922/56922fig1.jpg"> 图1。由苯乙烯、PFO 和5毫米水溶液 SDS 溶液组成的乳液中的液滴形态.(a)差分干扰对比 (DIC) 和(b)共焦荧光显微图像的乳液含有水荧光素。(c) DIC 和(d)含有油溶性荧光香豆素102的乳剂的共焦荧光显微图像。<a href="//cloudflare-jove-com.bdigitaluss.remotexs.co/files/ftp_upload/56922/56922fig1large.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/56922/56922fig2.jpg"> 图2。采用苯乙烯、PFO 和5毫米水溶液 SDS 的乳液组成的空心聚苯乙烯颗粒和微胶囊的形貌。(a) SEM 和(b)空心聚苯乙烯颗粒的茎图像。(c) SEM 和(d)微胶囊的茎图像。<a href="//cloudflare-jove-com.bdigitaluss.remotexs.co/files/ftp_upload/56922/56922fig2large.jpg" target="_blank">请单击此处查看此图的较大版本.</a>

Watch this Scientific Journal Video about Preparation of Hollow Polystyrene Particles and Microcapsules by Radical Polymerization of Janus Droplets Consisting of Hydrocarbon and Fluorocarbon Oils at J

Preparation of Hollow Polystyrene Particles and Microcapsules by Radical Polymerization of Janus Droplets Consisting of Hydrocarbon and Fluorocarbon Oils

由烃类和氟碳油组成的同液滴的自由基聚合制备空心聚苯乙烯颗粒和微胶囊

介绍了用苯乙烯、氟-n-辛烷和水溶液 SDS (硫酸钠) 溶液制备空心高分子颗粒和微胶囊的方法。

In this article, we have demonstrated a method for producing hollow particles and microcapsules using oil droplets consisting of hydrocarbon oil (styrene) ...

preparation-hollow-polystyrene-particles-microcapsules-radical

Universidad San Sebastian

Research

JoVE Journal

Chemistry

9.9K 次观看.  Tokyo University of Science. 介绍了用苯乙烯、氟-n-辛烷和水溶液 SDS (硫酸钠) 溶液制备空心高分子颗粒和微胶囊的方法。

视频: Preparation of Hollow Polystyrene Particles and Microcapsules by Radical Polymerization of Janus Droplets Consisting of Hydrocarbon and Fluorocarbon Oils

Synthesis of Poly(N-isopropylacrylamide) Janus Microhydrogels for Anisotropic Thermo-responsiveness and Organophilic/Hydrophilic Loading Capability

Janus microparticles are compartmentalized particles with differing molecular structures and/or functionality on each of their two sides. Because of this unique property, Janus microparticles have been recognized as a new class of materials, thereby attracting a great deal of attention from various research fields. The versatility of these microparticles has been exemplified through their uses as building blocks for self-assembly, electrically responsive actuators, emulsifiers for painting and cosmetics, and carriers for drug delivery. This study introduces a detailed protocol that explicitly describes a synthetic method for designing novel Janus microhydrogels composed of a single base material, poly(N-isopropylacrylamide) (PNIPAAm). Janus microdroplets are firstly generated via a hydrodynamic focusing microfluidic device (HFMD) based on the separation of a supersaturated aqueous NIPAAm monomer solution and subsequently polymerized through exposure to UV irradiation. The resulting Janus microhydrogels were found to be entirely composed of the same base material, featured an easily identifiable compartmentalized morphology, and exhibited anisotropic thermo-responsiveness and organophilic/hydrophilic loading capability. We believe that the proposed method introduces a novel hydrogel platform with the potential for advanced synthesis of multi-functional Janus microhydrogels.

Synthesis of PolyN-isopropylacrylamide Janus Microhydrogels for Anisotropic Thermo-responsiveness and Organophilic/Hydrophilic Loading Capability

We present a protocol to synthesize Janus microhydrogels composed entirely of the same base material, poly(N-isopropylacrylamide) (PNIPAAm), with a clearly compartmentalized structure base on the phase separation of a supersaturated NIPAAm monomer solution. The synthesized Janus microhydrogels show unique properties such as anisotropic thermo-responsiveness and organophilic/hydrophilic loading capability.

合成聚（<em&gt;ñ</em&gt; -isopropylacrylamide）剑锋Microhydrogels各向异性热响应能力和亲有机/亲水承载能力

Janus microparticles are compartmentalized particles with differing molecular structures and/or functionality on each of their two sides. Because of this ...

科研

化学

Using Polystyrene-block-poly(acrylic acid)-coated Metal Nanoparticles as Monomers for Their Homo- and Co-polymerization

We present a template-free method for &#8220;polymerizing&#8221; nanoparticles into long chains without side branches. A variety of nanoparticles are encapsulated in polystyrene-block-poly(acrylic acid) (PSPAA) shells and then used as monomers for their self-assembly. Spherical PSPAA micelles upon acid treatment are known to assemble into cylindrical micelles. Exploiting this tendency, the core-shell nanoparticles are induced to aggregate, coalesce, and then transform into long chains. When more than one type of nanoparticles are used, random and block &#8220;copolymers&#8221; of nanoparticles can be obtained. Detailed procedures are reported for the PSPAA encapsulation of nanoparticles, homo- and co-polymerization of the core-shell nanoparticles, separation and purification of the resulting nanoparticle chains. Transformations of single-line chains into double- and triple-line chains are also presented. The synergy between the polymer shell and the embedded nanoparticles leads to an unusual chain-growth polymerization mode, giving long nanoparticle chains that are distinct from the products of the traditional step-growth aggregation process.

Using Polystyrene-block-polyacrylic acid-coated Metal Nanoparticles as Monomers for Their Homo- and Co-polymerization

We report protocols for &#8220;polymerizing&#8221; various types of polymer-encapsulated metal nanoparticles into long chains of &#8220;homo-&#8220; and &#8220;co-polymers&#8221;.

使用聚苯乙烯<em&gt;块</em&gt; - 聚（丙烯酸）涂层的金属纳米颗粒作为单体他们均聚物和共聚物聚合

We present a template-free method for &#8220;polymerizing&#8221; nanoparticles into long chains without side branches. A variety of nanoparticles are ...

High-throughput Synthesis of Carbohydrates and Functionalization of Polyanhydride Nanoparticles

Transdisciplinary approaches involving areas such as material design, nanotechnology, chemistry, and immunology have to be utilized to rationally design efficacious vaccines carriers. Nanoparticle-based platforms can prolong the persistence of vaccine antigens, which could improve vaccine immunogenicity1. Several biodegradable polymers have been studied as vaccine delivery vehicles1; in particular, polyanhydride particles have demonstrated the ability to provide sustained release of stable protein antigens and to activate antigen presenting cells and modulate immune responses2-12.
The molecular design of these vaccine carriers needs to integrate the rational selection of polymer properties as well as the incorporation of appropriate targeting agents. High throughput automated fabrication of targeting ligands and functionalized particles is a powerful tool that will enhance the ability to study a wide range of properties and will lead to the design of reproducible vaccine delivery devices.
The addition of targeting ligands capable of being recognized by specific receptors on immune cells has been shown to modulate and tailor immune responses10,11,13 C-type lectin receptors (CLRs) are pattern recognition receptors (PRRs) that recognize carbohydrates present on the surface of pathogens. The stimulation of immune cells via CLRs allows for enhanced internalization of antigen and subsequent presentation for further T cell activation14,15. Therefore, carbohydrate molecules play an important role in the study of immune responses; however, the use of these biomolecules often suffers from the lack of availability of structurally well-defined and pure carbohydrates. An automation platform based on iterative solution-phase reactions can enable rapid and controlled synthesis of these synthetically challenging molecules using significantly lower building block quantities than traditional solid-phase methods16,17.
Herein we report a protocol for the automated solution-phase synthesis of oligosaccharides such as mannose-based targeting ligands with fluorous solid-phase extraction for intermediate purification. After development of automated methods to make the carbohydrate-based targeting agent, we describe methods for their attachment on the surface of polyanhydride nanoparticles employing an automated robotic set up operated by LabVIEW as previously described10. Surface functionalization with carbohydrates has shown efficacy in targeting CLRs10,11 and increasing the throughput of the fabrication method to unearth the complexities associated with a multi-parametric system will be of great value (Figure 1a).

In this article, a high throughput method is presented for the synthesis of oligosaccharides and their attachment to the surface of polyanhydride nanoparticles for further use in targeting specific receptors on antigen presenting cells.

碳水化合物和聚酸酐纳米粒子功能化的高通量合成

Transdisciplinary approaches involving areas such as material design, nanotechnology, chemistry, and immunology have to be utilized to rationally design ...

生物工程

High Throughput Single-cell and Multiple-cell Micro-encapsulation

Microfluidic encapsulation methods have been previously utilized to capture cells in picoliter-scale aqueous, monodisperse drops, providing confinement from a bulk fluid environment with applications in high throughput screening, cytometry, and mass spectrometry. We describe a method to not only encapsulate single cells, but to repeatedly capture a set number of cells (here we demonstrate one- and two-cell encapsulation) to study both isolation and the interactions between cells in groups of controlled sizes. By combining drop generation techniques with cell and particle ordering, we demonstrate controlled encapsulation of cell-sized particles for efficient, continuous encapsulation. Using an aqueous particle suspension and immiscible fluorocarbon oil, we generate aqueous drops in oil with a flow focusing nozzle. The aqueous flow rate is sufficiently high to create ordering of particles which reach the nozzle at integer multiple frequencies of the drop generation frequency, encapsulating a controlled number of cells in each drop. For representative results, 9.9 &mu;m polystyrene particles are used as cell surrogates. This study shows a single-particle encapsulation efficiency Pk=1 of 83.7% and a double-particle encapsulation efficiency Pk=2 of 79.5% as compared to their respective Poisson efficiencies of 39.3% and 33.3%, respectively. The effect of consistent cell and particle concentration is demonstrated to be of major importance for efficient encapsulation, and dripping to jetting transitions are also addressed. 
Introduction 
Continuous media aqueous cell suspensions share a common fluid environment which allows cells to interact in parallel and also homogenizes the effects of specific cells in measurements from the media. High-throughput encapsulation of cells into picoliter-scale drops confines the samples to protect drops from cross-contamination, enable a measure of cellular diversity within samples, prevent dilution of reagents and expressed biomarkers, and amplify signals from bioreactor products. Drops also provide the ability to re-merge drops into larger aqueous samples or with other drops for intercellular signaling studies.1,2 The reduction in dilution implies stronger detection signals for higher accuracy measurements as well as the ability to reduce potentially costly sample and reagent volumes.3 Encapsulation of cells in drops has been utilized to improve detection of protein expression,4 antibodies,5,6 enzymes,7 and metabolic activity8 for high throughput screening, and could be used to improve high throughput cytometry.9 Additional studies present applications in bio-electrospraying of cell containing drops for mass spectrometry10 and targeted surface cell coatings.11 Some applications, however, have been limited by the lack of ability to control the number of cells encapsulated in drops. Here we present a method of ordered encapsulation12 which increases the demonstrated encapsulation efficiencies for one and two cells and may be extrapolated for encapsulation of a larger number of cells.
To achieve monodisperse drop generation, microfluidic "flow focusing" enables the creation of controllable-size drops of one fluid (an aqueous cell mixture) within another (a continuous oil phase) by using a nozzle at which the streams converge.13 For a given nozzle geometry, the drop generation frequency f and drop size can be altered by adjusting oil and aqueous flow rates Qoil and Qaq. As the flow rates increase, the flows may transition from drop generation to unstable jetting of aqueous fluid from the nozzle.14 
When the aqueous solution contains suspended particles, particles become encapsulated and isolated from one another at the nozzle. For drop generation using a randomly distributed aqueous cell suspension, the average fraction of drops Dk containing k cells is dictated by Poisson statistics, where Dk = &lambda;k exp(-&lambda;)/(k!) and &lambda; is the average number of cells per drop. The fraction of cells which end up in the "correctly" encapsulated drops is calculated using Pk = (k x Dk)/&Sigma;(k' x Dk'). The subtle difference between the two metrics is that Dk relates to the utilization of aqueous fluid and the amount of drop sorting that must be completed following encapsulation, and Pk relates to the utilization of the cell sample. As an example, one could use a dilute cell suspension (low &lambda;) to encapsulate drops where most drops containing cells would contain just one cell. While the efficiency metric Pk would be high, the majority of drops would be empty (low Dk), thus requiring a sorting mechanism to remove empty drops, also reducing throughput.15
Combining drop generation with inertial ordering provides the ability to encapsulate drops with more predictable numbers of cells per drop and higher throughputs than random encapsulation. Inertial focusing was first discovered by Segre and Silberberg16 and refers to the tendency of finite-sized particles to migrate to lateral equilibrium positions in channel flow. Inertial ordering refers to the tendency of the particles and cells to passively organize into equally spaced, staggered, constant velocity trains. Both focusing and ordering require sufficiently high flow rates (high Reynolds number) and particle sizes (high Particle Reynolds number).17,18 Here, the Reynolds number Re =uDh/&nu; and particle Reynolds number Rep =Re(a/Dh)2, where u is a characteristic flow velocity, Dh [=2wh/(w+h)] is the hydraulic diameter, &nu; is the kinematic viscosity, a is the particle diameter, w is the channel width, and h is the channel height. Empirically, the length required to achieve fully ordered trains decreases as Re and Rep increase. Note that the high Re and Rep requirements (for this study on the order of 5 and 0.5, respectively) may conflict with the need to keep aqueous flow rates low to avoid jetting at the drop generation nozzle. Additionally, high flow rates lead to higher shear stresses on cells, which are not addressed in this protocol. The previous ordered encapsulation study demonstrated that over 90% of singly encapsulated HL60 cells under similar flow conditions to those in this study maintained cell membrane integrity.12 However, the effect of the magnitude and time scales of shear stresses will need to be carefully considered when extrapolating to different cell types and flow parameters. The overlapping of the cell ordering, drop generation, and cell viability aqueous flow rate constraints provides an ideal operational regime for controlled encapsulation of single and multiple cells.
Because very few studies address inter-particle train spacing,19,20 determining the spacing is most easily done empirically and will depend on channel geometry, flow rate, particle size, and particle concentration. Nonetheless, the equal lateral spacing between trains implies that cells arrive at predictable, consistent time intervals. When drop generation occurs at the same rate at which ordered cells arrive at the nozzle, the cells become encapsulated within the drop in a controlled manner. This technique has been utilized to encapsulate single cells with throughputs on the order of 15 kHz,12 a significant improvement over previous studies reporting encapsulation rates on the order of 60-160 Hz.4,15 In the controlled encapsulation work, over 80% of drops contained one and only one cell, a significant efficiency improvement over Poisson (random) statistics, which predicts less than 40% efficiency on average.12
In previous controlled encapsulation work,12 the average number of particles per drop &lambda; was tuned to provide single-cell encapsulation. We hypothesize that through tuning of flow rates, we can efficiently encapsulate any number of cells per drop when &lambda; is equal or close to the number of desired cells per drop. While single-cell encapsulation is valuable in determining individual cell responses from stimuli, multiple-cell encapsulation provides information relating to the interaction of controlled numbers and types of cells. Here we present a protocol, representative results using polystyrene microspheres, and discussion for controlled encapsulation of multiple cells using a passive inertial ordering channel and drop generation nozzle.

Combining monodisperse drop generation with inertial ordering of cells and particles, we describe a method to encapsulate a desired number of cells or particles in a single drop at kHz rates. We demonstrate efficiencies twice exceeding those of unordered encapsulation for single- and double-particle drops.

高吞吐量的单细胞和多细胞微胶囊

Microfluidic encapsulation methods have been previously utilized to capture cells in picoliter-scale aqueous, monodisperse drops, providing confinement ...

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 ...

Anionic Polymerization of an Amphiphilic Copolymer for Preparation of Block Copolymer Micelles Stabilized by &#960;-&#960; Stacking Interactions

In this study, an amphiphilic copolymer that includes a core-forming block with phenyl groups was synthesized by living anionic polymerization of phenyl glycidyl ether (PheGE) on methoxy-polyethylene glycol (mPEG-b-PPheGE). Characterization of the copolymer revealed a narrow molecular distribution (PDI &#60; 1.03) and confirmed the degree of polymerization of mPEG122-b-(PheGE)15. The critical micelle concentration of the copolymer was evaluated using an established fluorescence method with the aggregation behavior evaluated by dynamic light scattering and transmission electronic microscopy. The potential of the copolymer for use in drug delivery applications was evaluated in a preliminary manner including in vitro biocompatibility, loading and release of the hydrophobic anti-cancer drug doxorubicin (DOX). A stable micelle formulation of DOX was prepared with drug loading levels up to 14% (wt%), drug loading efficiencies &#62; 60% (w/w) and sustained release of drug over 4 days under physiologically relevant conditions (acidic and neutral pH, presence of albumin). The high drug loading level and sustained release is attributed to stabilizing &#960;-&#960; interactions between DOX and the core-forming block of the micelles.

The key steps of living anionic polymerization of phenyl glycidyl ether (PheGE) on methoxy-polyethylene glycol (mPEG-b-PPheGE) are described. The resulting block copolymer micelles (BCMs) were loaded with doxorubicin 14% (wt%) and sustained release of drug over 4 days under physiologically relevant conditions was obtained.

一个两亲性共聚物的阴离子聚合通过π-π堆积作用稳定嵌段共聚物胶束的制备

In this study, an amphiphilic copolymer that includes a core-forming block with phenyl groups was synthesized by living anionic polymerization of phenyl ...

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, ...

工程学

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 ...

A Droplet-Based Microfluidic Approach and Microsphere-PCR Amplification for Single-Stranded DNA Amplicons

Droplet-based microfluidics enable the reliable production of homogeneous microspheres in the microfluidic channel, providing controlled size and morphology of the obtained microsphere. A microsphere copolymerized with an acrydite-DNA probe was successfully fabricated. Different methods such as asymmetric PCR, exonuclease digestion, and isolation on streptavidin-coated magnetic beads can be used to synthesize single-stranded DNA (ssDNA). However, these methods cannot efficiently use large amounts of highly purified ssDNA. Here, we describe a microsphere-PCR protocol detailing how ssDNA can be efficiently amplified and separated from dsDNA simply by pipetting from a PCR reaction tube. The amplification of ssDNA can be applied as potential reagents for the DNA microarray and DNA-SELEX (Systematic evolution of ligands by exponential enrichment) processes.

This work provides a method for the fabrication of droplet-based microfluidic platforms and the application of polyacrylamide microspheres for microsphere-PCR amplification. The microsphere-PCR method makes it possible to obtain single-stranded DNA amplicons without separating double-stranded DNA.

由烃类和氟碳油组成的同液滴的自由基聚合制备空心聚苯乙烯颗粒和微胶囊

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