This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea Government (MSIP (Nos. 2014R1A2A1A01006527 and 2011-0030075).

1.母模通过光刻水动力聚焦微流控芯片（手足口病）的制备<ol><li>设计用于根据制造商的方案使用计算机辅助设计（CAD）软件的手足口病（ 图1a）的光掩模。 </li><li>冲洗用丙酮，异丙醇（IPA），和去离子（DI）水4&#39;的硅晶片，从晶片去除有机和无机灰尘。 </li><li>清洁带O 2等离子体的硅晶片在100瓦的功率为5分钟，以增加晶片和SU-8之间的接合强度。 </li><li>旋涂将4ml负光致抗蚀剂的SU-8 2150到晶片以3000rpm进行30秒以实现厚度150μm（在图1b b1）中 。 </li><li>放置在电炉上的SU-8涂布的晶片在65℃5分钟，设定温度至95℃，然后离开热板在晶片30分钟，软烘烤。 </li><li>放置设计光掩模在晶片上，并在一个掩模对准暴露于UV光（260毫焦耳厘米-2，26秒，10毫瓦厘米-2）（在图 B2 1b）中 。 </li><li>执行曝光后烘烤在电炉上（65℃5分钟，然后95℃，12分钟）。 </li><li>开发通过在10分钟的SU-8显影剂浴浸渍晶片，然后将其转移到新鲜的显影剂5秒，以获得清洁的表面。 </li><li>冲洗晶片20秒用DI水并用N 2气干燥它为10秒（在图 B3 1b）中 。使用制造晶片在第2节的主模聚二甲基硅氧烷（PDMS）铸造。 </li></ol> 2.通过PDMS铸造加工的手足口病<ol><li>使用1节作为主模铸造PDMS获得的图形晶片。 </li><li>混合的PDMS预聚物和在10的重量比的固化剂均匀地:​​1;例如，使用1克固化剂为10克PDMS预POLYM的呃。 </li><li>倒入PDMS预聚合物到主模和在真空室中脱气它为1小时（B4在图1b）。 </li><li>母模与PDMS预聚物放入烘箱中在65℃下3小时。 </li><li>切割该固化的PDMS成用锋利的解剖刀单个芯片的规模。小心剥离用手从母模的固化的PDMS复制品。 </li><li>重复步骤2.2至2.5，以获得相同的PDMS复制品。 </li><li>入口冲床和出口孔成使用空穴冲床具有比连接管的外径稍小直径的副本中的一个。 </li><li>应用空气等离子体处理，使用一个电晕每个副本的接合面积。34 注意:使用电晕在通风良好的地方，以避免臭氧积聚。 </li><li>下降5微升甲醇到空气等离子处理的区域。精细对准两个相同的PDMS副本用手manipu制造的手足口病<html>特征研，并通过显微镜（B5 图1b）检查调整。 注意:空气等离子体处理过的PDMS复制品是相当粘且难以操纵。因此，5微升甲醇加入到空气等离子处理的表面以用作润滑剂。 </li><li>放置手足口病在设定至65℃过夜烘箱加强（B6在图1b）二PDMS复制品之间的结合。键的两个相同的PDMS复制品来增加手足口病的微通道的高度和操作过程中避免在微流体通道的微滴的堵塞。 </li></ol><img alt="图1" src="/files/ftp_upload/52813/52813fig1.jpg" /> 图1:手足口病的制备过程概述 （a）该光掩模为手足口病的设计参数。为手足口病的制作过程（ 二 ）插图。ftp_upload / 52813 / 52813fig1large.jpg"目标="_空白"&gt;点击此处查看该图的放大版本。 3.的NIPAAm丰富的制备（N-丰富）的NIPAAm和贫（N-差）由超饱和的NIPAAm相分离阶段<ol><li>使用涡旋混合器1;:以1 AW / w比例溶解于DI水中的NIPAAm单体例如，溶解在10ml去离子水将10克的NIPAAm的（ 图2a的第一图像）。 注意:一旦的NIPAAm单体在室温下充分溶解，溶液出现混浊（ 图2a的第二图像）。这种现象是第一个线索已经成功发生过饱和的NIPAAm单体的那溶解度诱导相分离。 </li><li>允许单体溶液以在垂直位置在室温下静置至少15分钟。顶部相是富N相，和更密集底部相是N差相（ 图2a的第三图像）。个的密度简丰富和N-差相分别为0.93±0.01和0.99±0.01克厘米-3。15 </li><li>当分离两相界面变得清晰，轻轻取出加入2ml从富N和N-差相单体溶液通过不使用吸管扰乱这个接口。 </li><li>加入4毫克N，N&#39;甲基双丙烯酰胺（MBAAm）作为交联剂和4mg 4-（2-羟基乙氧基）苯基- （2-羟基-2-丙基）酮作为光引发剂到N-丰富和N所提取的国定贫困单体溶液以制备用于低交联剂浓度芯的液体1和2（2毫克毫升-1）样品（b1和图2b b2）中。 </li><li>重复先前的步骤3.3，并添加80毫克MBAAm和4mg 4-（2-羟基乙氧基）苯基 - （2-羟基-2-丙基）酮向每个提取的N-丰富和N-差单体溶液以制备芯流体图1和2对于高交联剂浓度（40毫克毫升-1）样品（b3和图 B4URE 2b）中。 </li><li>溶解油表面活性剂的10％（重量）到矿物油来制备鞘液（b5在图2b）。 </li></ol><img alt="图2" src="/files/ftp_upload/52813/52813fig2.jpg" /> 图2:对杰纳斯Microhydrogel合成材料准备 （ 一 ）通过的NIPAAm过饱和相分离富N和N-差单体溶液制备方法。 （ 二 ）材料，并在协议中使用实验装置的详细信息。 <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/52813/52813fig2large.jpg" target="_blank">请点击此处查看该图的放大版本。</a> 使用手足口病剑锋Microhydrogels 4.合成<ol><li>负载2 ml的核心的流体1和2（B1，B2或B3，B4在连接古尔2b）和所述鞘液（b5在图2b）成三个独立3毫升注射器。 </LI&gt; <li>装入注射器到注射器泵和用管（ 图（b）中 。使用管将手足口病的流体出口连接至收集储存各注射器连接到手足口病的适当的流体入口。 </li><li>设定注射器泵和在2,2，和10微升分钟-1的流速注入芯流体1和流体2和鞘液，分别。 </li><li> （可选的）调谐芯流体1和流体2的流速以调节的Janus微滴的每一侧的相对体积比。 </li><li> UV光源垂直约1cm从收集容器离开的位置。切换UV光源和视觉监控连续生产剑锋microhydrogels的。 注意:使用UV监测microhydrogel生产时保护护目镜。 </li><li>收集制造剑锋microhydrogels成一个锥形管，并使用IPA清洗。然后，离心锥形管（780克5分钟），以解决microhydrogels。 </li><li>重复步骤4.6几次以除去完全包围的Janus microhydrogels矿物油。 </li><li>重复步骤4.6但使用去离子水为0.005％的水的表面活性剂（体积/体积）代替IPA以除去剩余的IPA周围的Janus microhydrogels。 </li><li>在10ml的小瓶含去离子水储存充分洗涤剑锋microhydrogels。 </li></ol> 5.剑锋Microhydrogels的各向异性热反应性分析<ol><li>使用移液管，从第4节合成的Janus microhydrogels放入一个24孔板中。允许直到在孔的底部表面上形成的单层的microhydrogels沉降15秒。 </li><li>获得使用具有5X物镜直立光学显微镜在24℃下实现Ja​​nus microhydrogel的图像。 </li><li>设置孔板下的热电模块和控制该模块的电压，以增加包含的Janus微将溶液的温度水凝胶至32℃。 </li><li>在32℃下再次通过使用直立光学显微镜用5X物镜获取的Janus microhydrogel的图像。 </li><li>重复步骤5.2-5.4 24次，同时注意选择不同的剑锋microhydrogel进行统计分析。 </li><li>从在24和32℃下不同的Janus microhydrogels的25幅图像，测量根据制造商的说明使用图像分析软件的Janus microhydrogels的富PN和PN-差部分的半径。 </li></ol>

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Commun. 47 (9), 2634-2636 (2011).</li><li>Hauber, K., Drier, T., Beebe, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=PDMS+bonding+by+means+of+a+portable,+low-cost+corona+system.">PDMS bonding by means of a portable, low-cost corona system.</a> Lab chip. 6 (12), 1548-1549 (2006).</li><li>Nisisako, T., Torii, T., Takahashi, T., Takizawa, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Synthesis+of+monodisperse+bicolored+Janus+particles+with+electrical+anisotropy+using+a+microfluidic+co-flow+system.">Synthesis of monodisperse bicolored Janus particles with electrical anisotropy using a microfluidic co-flow system.</a> Adv. Mater. 18 (9), 1152-1156 (2006).</li><li>Seiffert, S., Romanowsky, M. B., Weitz, D. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Janus+microgels+produced+from+functional+precursor+polymers.">Janus microgels produced from functional precursor polymers.</a> Langmuir. 26 (18), 14842-14847 (2010).</li><li>Peppas, N. A., Hilt, J. Z., Khademhosseini, A., Langer, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Hydrogels+in+biology+and+medicine:+from+molecular+principles+to+bionanotechnology.">Hydrogels in biology and medicine: from molecular principles to bionanotechnology.</a> Adv. Mater. 18 (11), 1345-1360 (2006).</li></ol>

The authors declare that they have no competing financial interests.

两种不混溶基材料通常用于合成的Janus microhydrogels。直到最近，由相同的基本材料制成的Janus microhydrogels很少报道和所报告的Janus microhydrogels没有一个明确的内部的形态，由于所引起的元件材料的可混溶性的紊乱。35，36在这个协议中，我们展示了一个方法合成完全在单一基体材料，PNIPAAm的组成，具有明确条块结构的Janus microhydrogels。 如以合成的Janus microhydrogels一个关键步骤中，我们介绍过饱和的NIPAAm单体溶液的相分离现象。从相分离现象的收集富N和N-相位不佳解决方案是不混溶和丰富的N和N-差相之间的干扰几乎可以忽略不计。 N型丰富和N-差相在微​​滴剑锋这混溶是马intained在手足口病和剑锋microhydrogels的形态，甚至在聚合后保存。 我们施加的手足口病，以合成的Janus microhydrogels因为该协议允许容易地生成单分散的Janus microhydrogels的每小时10 5的Janus microhydrogels的速率的方法。在这项工作中新设计的手足口病已正确制造用于与几百微米的数量级内的尺寸生产的Janus microhydrogels;手足口病未来的设计可能是能够生产更小尺寸的剑锋microhydrogels。 剑锋microhydrogels的进一步研究发现从富N和N-差不同阶段的NIPAAm浓度源于两种不同的特性。首先，不同的NIPAAm浓度构成的两面神microhydrogels响应于温度变化表现出各向异性热 - 反应行为。至交联剂比率的单体是众所周知的可怕ctly影响水凝胶的溶胀水平37的NIPAAm分子的量在富N相通常比在N-差相高得多。因此，单体与交联剂在富N相比大于在N差相较大时交联剂的相同浓度使用这两个阶段。因此，两面神水凝胶的富PN-部分经受与响应于温度变化的PN贫部相比较大的体积变化。其次，剑锋microhydrogels展出亲有机/亲水承载能力无交叉混合。脂溶性染料充分溶解在N富单体溶液中，同时该水溶性染料被充分溶解在N差单体溶液。富 - N和N-差单体溶液的对比溶出性质是从与各单体溶液的NIPAAm分子相互作用后剩下的自由水分子的可用性差而得。由于POSSS弯一个同等较高数量剩自由水分子比的N富单体溶液中，N-差单体溶液可以很容易地溶解水溶性染料中的亲水性的极性分子。与此相反，水溶性染料在富N-二单体溶液，其可只用几个自由水分子相互作用表现出溶解性差。因此，当用脂溶性染料混合富N和N-差单体溶液显示出相反的结果。合成的Janus microhydrogels可以用作与没有交叉混合条块内部形态亲有机/亲水双物质载体。 未来的应用的Janus microhydrogels的新颖的特征可被用于开发官能微粒和实现多药物包封。我们相信，根据该过饱和的NIPAAm的相分离为这些的Janus microhydrogels合成协议引入了一个新的本草升平台与多功能剑锋microhydrogels先进合成的潜力。

Hydrogels are a network of hydrophilic polymer chains.1 An increasing amount of research in the field of hydrogels has promoted significant advances and revealed their similarity to biological tissues; the properties of hydrogels allow the uptake of large amounts of water while maintaining their structure. Environmentally responsive hydrogels have also been studied extensively because of their ability to swell or shrink reversibly in response to external stimuli.2 Several triggers, including temperature,3-5 pH,6,7 light,8,9 electric fields,10,11 and specific molecules, such as glucose,12,13 have been suggested to control the geometric shape of hydrogels. Among the many environmentally responsive hydrogels currently available, poly(N-isopropylacrylamide) (PNIPAAm), a well-known thermo-responsive hydrogel, exhibits volume shrinkage above a low critical solution temperature (LCST) of 32 &#176;C.14 A recent study by Sasaki et al.15 reported the intriguing liquid-liquid phase separation of supersaturated NIPAAm, which is the monomer of PNIPAAm. According to this report, supersaturated NIPAAm was dissolved with a 10-fold molar excess of H2O, and soon after, the solution separated into two liquid phases when allows to stand at a temperature above 25 &#176;C; by contrast, dilute NIPAAm was dissolved homogeneously under the same conditions.
Microparticles made of environmentally responsive hydrogels are fascinating candidates for application in drug delivery,16,17 catalysis,18 sensing,19,20 and photonics.21 Traditional synthetic methods including emulsion polymerization, are used to produce hydrogel microparticles with polydispersity.22,23 However, certain applications require microparticles with a narrow size distribution, for example, to stabilize the pharmacokinetics of drug delivery.24 Irregularly shaped or polydisperse embolic microparticles aggregate proximally into clusters, leading to chronic inflammatory responses in embolic particles for cancer therapeutic treatment.25,26
The microfluidic approach is at the forefront of research as a means of fabricating micro-sized particles with narrow size distributions and complex shapes.27-31 The advantages of fabricating microparticles in the microfluidic device are predicated by the small characteristic length of the microfluidic device, which results in a low Reynolds number. In contrast to traditional bulk emulsification where drops are formed in parallel, microdroplets produced in microfluidic devices are generated in series and subsequently polymerized into microparticles upon exposure to UV irradiation. The fundamental principle of droplet formation using a microfluidic device is balance between the interfacial tension and the shear force of the sheath fluid acting on the core fluid. 
Despite the obvious advantages of microfluidic fabrication of droplets/particles, Janus droplets/particles consisting of the same base material are rarely reported because the internal morphology of these droplets/particles is generally disturbed by the diffusion and perturbation of the core fluids. To circumvent this intrinsic limitation, two groups recently reported the preparation of the Janus microparticles by employing heat-induced phase separation of colloidal nanoparticles and UV-directed phase separation.32,33
To this end, we report a microfluidic approach to synthesize Janus microhydrogels entirely composed of a single base material and obtain a product with clearly compartmentalized morphology. Our approach is based on the primary concept of liquid-liquid phase separation of supersaturated NIPAAm monomer. The resulting Janus microhydrogels were found to possess unique properties including anisotropic thermo-responsiveness and organophilic/hydrophilic loading capability.

<table border="0" cellpadding="0" cellspacing="0" width="590">
	<tbody>
		<tr height="20">
			<td height="20" style="height:20px;width:216px;">Silicon wafer</td>
			<td style="width:88px;">LG Siltron</td>
			<td style="width:119px;">4&#34;, Test grade</td>
			<td style="width:167px;">Wafer for master mold fabrication</td>
		</tr>
		<tr height="60">
			<td height="60" style="height:60px;width:216px;">Acetone</td>
			<td style="width:88px;">Samchun Pure Chemical</td>
			<td style="width:119px;">A0097</td>
			<td>Cleaning silicon wafer</td>
		</tr>
		<tr height="60">
			<td height="60" style="height:60px;width:216px;">Isopropyl alcohol (IPA)</td>
			<td style="width:88px;">Daejung Chemicals &#38; Metals</td>
			<td style="width:119px;">5035-4404</td>
			<td>Cleaning silicon wafer</td>
		</tr>
		<tr height="60">
			<td height="60" style="height:60px;width:216px;">Water purification system</td>
			<td style="width:88px;">Merck Millipore</td>
			<td style="width:119px;">EMD Millipore RIOs Essential 5</td>
			<td>Prepering&#160; deionized water</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:216px;">O2 plasma machine</td>
			<td style="width:88px;">Femto Science</td>
			<td style="width:119px;">VITA-A</td>
			<td>Cleaning silicon wafer</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:216px;">SU-8 2150 negative photoresist</td>
			<td style="width:88px;">MicroChem</td>
			<td style="width:119px;">Y111077 0500L1GL</td>
			<td>Photoresist for master mold fabrication</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:216px;">Hot plate</td>
			<td style="width:88px;">Misung Scientific</td>
			<td style="width:119px;">HP330D, HP150D</td>
			<td>Baking SU-8</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:216px;">SU-8 developer</td>
			<td style="width:88px;">Microchem</td>
			<td style="width:119px;">Y020100 4000L1PE</td>
			<td>Developing SU-8</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:216px;">Mask aligner system for photolithograpy</td>
			<td style="width:88px;">Shinu Mst Co.</td>
			<td style="width:119px;">CA-6M</td>
			<td>Photolithography</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:216px;">Sylgard 184 silicone elastomer kit</td>
			<td style="width:88px;">Dow Corning</td>
			<td style="width:119px;">1064891</td>
			<td>PDMS casting</td>
		</tr>
		<tr height="80">
			<td height="80" style="height:80px;width:216px;">Laboratory Corona Treater</td>
			<td style="width:88px;">Electro-technic Products Inc.</td>
			<td style="width:119px;">Model BD-20AC</td>
			<td>PDMS air plasma treatment&#160;</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:216px;">N-isopropylacrylamide (NIPAAm)</td>
			<td style="width:88px;">Sigma-Aldrich</td>
			<td style="width:119px;">415324-50G</td>
			<td>Monomer</td>
		</tr>
		<tr height="60">
			<td height="60" style="height:60px;width:216px;">N,N&#39;-methylenebisacrylamide (MBAAm)</td>
			<td style="width:88px;">Sigma-Aldrich</td>
			<td style="width:119px;">146072-100G</td>
			<td>Crosslinker of NIPAAm</td>
		</tr>
		<tr height="60">
			<td height="60" style="height:60px;width:216px;">4-(2-hydroxyethoxy)phenyl-(2-hydroxy-2-propyl)ketone, Irgacure 2959</td>
			<td style="width:88px;">BASF</td>
			<td style="width:119px;">55047962</td>
			<td>Photoinitiator of NIPAAm</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">ABIL EM 90</td>
			<td style="width:88px;">Evonik Industries</td>
			<td style="width:119px;">201109</td>
			<td>Sufactant for oil</td>
		</tr>
		<tr height="60">
			<td height="60" style="height:60px;width:216px;">Vortex mixer</td>
			<td style="width:88px;">Scientific Industries Inc.</td>
			<td style="width:119px;">Vortex-Genie 2</td>
			<td>Mixing</td>
		</tr>
		<tr height="60">
			<td height="60" style="height:60px;width:216px;">Tygon tubing</td>
			<td style="width:88px;">Saint-Gobain</td>
			<td style="width:119px;">I.D. 1/32&#34;, O.D. 3/32&#34;, Wall 1/32&#34;</td>
			<td>Connecting tube between syringes and HFMD</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:216px;">UV light source</td>
			<td style="width:88px;">Hamamatsu</td>
			<td style="width:119px;">Spot light source LC8</td>
			<td>Polymerization from NIPAAm to PNIPAAm</td>
		</tr>
		<tr height="60">
			<td height="60" style="height:60px;width:216px;">Syringes, NORM-JECT (3ml)</td>
			<td style="width:88px;">Henke-Sass Wolf GmbH</td>
			<td style="width:119px;">22767</td>
			<td>Loading of materials</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:216px;">Syringe pump</td>
			<td style="width:88px;">KD Scientific</td>
			<td style="width:119px;">KDS model 200</td>
			<td>Perfusion of materials</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:216px;">Tegitol Type NP-10</td>
			<td style="width:88px;">Sigma-Aldrich</td>
			<td style="width:119px;">NP10-500ML</td>
			<td>Surfactant for water</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:216px;">Oil red O</td>
			<td style="width:88px;">Sigma-Aldrich</td>
			<td style="width:119px;">O0625-25G</td>
			<td>Dye for N-rich phase</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:216px;">Oil Blue N</td>
			<td style="width:88px;">Sigma-Aldrich</td>
			<td style="width:119px;">391557-5G</td>
			<td>Dye for N-rich phase</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:216px;">Yellow food dye</td>
			<td style="width:88px;">Edentown F&#38;B</td>
			<td style="width:119px;">NA</td>
			<td>Dye for N-poor phase</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:216px;">Green food dye</td>
			<td style="width:88px;">Edentown F&#38;B</td>
			<td style="width:119px;">NA</td>
			<td>Dye for N-poor phase</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Power supply</td>
			<td style="width:88px;">Agilent</td>
			<td style="width:119px;">E3649A</td>
			<td>Power soruce for thermoelectric moduel</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Thermoelectric module</td>
			<td style="width:88px;">Peltier</td>
			<td style="width:119px;">FALC1-12710T125</td>
			<td>Temparature control</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Centrifuge machine</td>
			<td style="width:88px;">Labogene</td>
			<td style="width:119px;">1248R</td>
			<td>Settling down microhydrogels</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">24-well plate</td>
			<td style="width:88px;">SPL Life Sciences</td>
			<td style="width:119px;">32024</td>
			<td>Reservoir for observation</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Optical microscope</td>
			<td style="width:88px;">Nikon</td>
			<td style="width:119px;">ECLIPSE 80i</td>
			<td>Optical observation</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Image analysis software</td>
			<td style="width:88px;">IMT i-Solution Inc.</td>
			<td style="width:119px;">iSolutions DT</td>
			<td>Measurement of radius</td>
		</tr>
	</tbody>
</table>

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.

图3a给出用于通过手足口病，合成的Janus microhydrogels实验装置的示意图。富 - N和N-差相恰恰注入手足口病为核心的流体1和2，然后合并并在由矿物油的，因为瑞利毛细不稳定性的鞘流体孔口分成的Janus微滴。因此， 如图3b中已成功生成富N和N-差相构成的Janus微滴。微滴的直径为190微米具有小于2％的变化（CV）的系数。观察到的Janus微滴的清晰条块内部形态，因为这两个阶段被稳定地分离。应当注意的是，每一个阶段是在其它不混溶的各相之间的扩散几乎可以忽略不计。一个微滴内的富 - N和N-差相的体积比为:C通过改变各单体溶液的流速通过注射器泵中， 如图3c中所示ontrolled。在富N和N-差单体溶液中加入光引发剂，然后通过暴露于UV光引发的，从而诱导富N和N-差分阶段PN-丰富和PN-差，分别的聚合。 <img alt="图3" src="/files/ftp_upload/52813/52813fig3.jpg" /> 图3:使用手足口病剑锋微滴生成的手足口病的产生剑锋微滴（ 一 ）示意图。 （ 二 ）N丰富和N-差相组成的微滴剑锋光学显微照片。与富N和N-差的阶段不同的体积比（c）获得剑锋微滴（1:3,1:1,3:1）。 <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/52813/52813fig3large.jpg" target="_blank">请点击此处查看大图</a>版本这个数字。 图4描述了造成剑锋microhydrogel的丰富PN和PN-贫困地区之间的NIPAAm单体浓度差异microhydrogels的各向异性热水瓶响应行为。的Janus microhydrogels以2和40mg毫升-1不同交联剂浓度制成审查交联剂浓度对所得到的水凝胶的热响应行为的影响。如在图4中所示，在交联剂浓度的增加导致了在上方和下方的LCST的microhydrogels的可逆体积变化减小。 <img alt="图4" src="/files/ftp_upload/52813/52813fig4.jpg" /> 图4:剑锋Microhydrogels的温度响应在剑锋microhydrogels各向异性量的变化响应。温度变化是由在富PN和PN-贫困地区之间的NIPAAm单体浓度的差异引起的。 <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/52813/52813fig4large.jpg" target="_blank">请点击此处查看该图的放大版本。</a> 图5a示出的示意图，并且响应于环境和温度变化的Janus微滴/ microhydrogels的光学显微照片:24℃下在油中，24℃的水中和32℃的水中。量化热响应性，我们测量了的Janus微滴/ microhydrogels的半径， 如图5b所示 。在图5b中的误差棒表示所测量的半径的25的Janus microhydrogels标准偏差。实现Janus microhydrogels的各部分的半径是从利用图像分析软件的拍摄图像来确定。在单体液滴状态（在图5a和图5b a1）中，富- N和N-差相的半径几乎相同。聚合（A2 图5a和图二 ）由于在N穷相，在比较低的NIPAAm单体浓度后观察到的剑锋microhydrogels的丰富PN和PN-贫困地区之间的半径在微小的差别的N-丰富的阶段。剑锋microhydrogels的两个丰富PN和PN-贫困地区都在去离子水中充分膨大在室温下。在溶胀步骤中，PN富部分的溶胀比的PN贫部分的更大;必然，获得雪人字形剑锋microhydrogels（ 图5a和图B A3）。有趣的是，microhydrogels的在32℃下收缩后的半径类似于在手足口病产生的微滴的半径（A4在图5a和图5b）。 图5:用各向异性热响应剑锋Microhydrogels（ 一 ）示意图和剑锋微滴/ microhydrogels的光学显微（比例尺为100微米）。 （ 二 ）在应对环境和温度变化剑锋微滴/ microhydrogels半径变化:24℃的油中，24℃的水，32℃的水。 <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/52813/52813fig5large.jpg" target="_blank">请点击此处查看该图的放大版本。</a> 图6a示出富- N和N-差单体溶液的溶解性质。脂溶性染料（油红O和油蓝N）和水溶性染料（黄色和绿色食品染料）强烈倾向于溶解到N RICH和N-差单体溶液，分别。基于这些溶出特征，通过使用所提出的协议生成含有脂肪 - 和水溶性染料无交叉混合的Janus的NIPAAm单体的微滴。油红O和绿色食用色素分别选作代表亲有机物质和亲水性的材料， 如图6b所示 。紫外聚合后，成功地合成了含有两种染料的Janus microhydrogels，在图6c中所示。这些结果表明实现Janus microhydrogel可以为亲有机物质/亲水双物质载体得到应用。 <img alt="图6" src="/files/ftp_upload/52813/52813fig6.jpg" /> 图6:有机物质的剑锋Microhydrogels /亲水荷载能力 （ 一 ）丰富的N和N-差单体溶液溶解性能。脂肪 - 和水溶性染料强烈preferrED在富N和N-差单体溶液分别溶解。含有脂肪-和水溶性染料无交叉混合的Janus微滴（b）的生成。 （c）含脂肪-和水溶性染料聚合剑锋microhydrogels。 <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/52813/52813fig6large.jpg" target="_blank">请点击此处查看该图的放大版本。</a>

Watch this Scientific Journal Video about Synthesis of PolyN-isopropylacrylamide Janus Microhydrogels for Anisotropic Thermo-responsiveness and Organophilic/Hydrophilic Loading Capability at JoVE.com

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 ...

synthesis-poly-n-isopropylacrylamide-janus-microhydrogels-for

Nanyang Technological University

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JoVE Journal

Chemistry

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

9.9K 次观看.  Pohang University of Science and Technology (POSTECH). 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.

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

Synthesis, Cellular Delivery and In vivo Application of Dendrimer-based pH Sensors

The development of fluorescent indicators represented a revolution for life sciences. Genetically encoded and synthetic fluorophores with sensing abilities allowed the visualization of biologically relevant species with high spatial and temporal resolution. Synthetic dyes are of particular interest thanks to their high tunability and the wide range of measureable analytes. However, these molecules suffer several limitations related to small molecule behavior (poor solubility, difficulties in targeting, often no ratiometric imaging allowed). In this work we introduce the development of dendrimer-based sensors and present a procedure for pH measurement in vitro, in living cells and in vivo. We choose dendrimers as ideal platform for our sensors for their many desirable properties (monodispersity, tunable properties, multivalency) that made them a widely used scaffold for several biomedical devices. The conjugation of fluorescent pH indicators to the dendrimer scaffold led to an enhancement of their sensing performances. In particular dendrimers exhibit reduced cell leakage, improved intracellular targeting and allow ratiometric measurements. These novel sensors were successfully employed to measure pH in living HeLa cells and in vivo in mouse brain.

Synthesis, Cellular Delivery and In vivo Application of Dendrimer-based pH Sensors

Fluorescence sensors are powerful tools in life science. Here we describe a methodology to synthesize and use dendrimer-based fluorescent sensors to measure pH in living cells and in vivo. The dendritic scaffold enhances the properties of conjugated fluorescent dyes leading to improved sensing properties.

合成，细胞和交货<em&gt;在体内</em&gt;的树状为基础的pH值传感器应用

The development of  fluorescent indicators represented a revolution for life sciences. Genetically  encoded and synthetic fluorophores with sensing ...

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 ...

Synthesis of Indoxyl-glycosides for Detection of Glycosidase Activities

Indoxyl glycosides proved to be valuable and versatile tools for monitoring glycosidase activities. Indoxyls are released by enzymatic hydrolysis and are rapidly oxidized, for example by atmospheric oxygen, to indigo type dyes. This reaction enables fast and easy screening in vivo without isolation or purification of enzymes, as well as rapid tests on agar plates or in solution (e.g., blue-white screening, micro-wells) and is used in biochemistry, histochemistry, bacteriology and molecular biology. Unfortunately the synthesis of such substrates proved to be difficult, due to various side reactions and the low reactivity of the indoxyl hydroxyl function. Especially for glucose type structures low yields were observed. Our novel approach employs indoxylic acid ester as key intermediates. Indoxylic acid esters with varied substitution patterns were prepared on scalable pathways. Phase transfer glycosylations with those acceptors and peracetylated glycosyl halides can be performed under common conditions in high yields. Ester cleavage and subsequent mild silver mediated glycosylation yields the peracetylated indoxyl glycosides in high yields. Finally deprotection is performed according to Zempl&#233;n.

Indoxyl glycosides are well-established and widely used tools for enzyme screening and enzyme activity monitoring. Especially for glucose type structures previous syntheses proved to be challenging and low yielding. Our novel approach employs indoxylic acid esters as precious intermediates to yield a considerable number of indoxyl glycosides in good yields.

的吲哚酚苷的检测糖苷酶活动的合成

Indoxyl glycosides proved to be valuable and versatile tools for monitoring glycosidase activities. Indoxyls are released by enzymatic hydrolysis and are ...

Protocol for the Synthesis of Ortho-trifluoromethoxylated Aniline Derivatives

Molecules bearing trifluoromethoxy (OCF3) group often show desired pharmacological and biological properties. However, facile synthesis of trifluoromethoxylated aromatic compounds remains a formidable challenge in organic synthesis. Conventional approaches often suffer from poor substrate scope, or require use of highly toxic, difficult-to-handle, and/or thermally labile reagents. Herein, we report a user-friendly protocol for the synthesis of methyl 4-acetamido-3-(trifluoromethoxy)benzoate using 1-trifluoromethyl-1,2-benziodoxol-3(1H)-one (Togni reagent II). Treating methyl 4-(N-hydroxyacetamido)benzoate (1a) with Togni reagent II in the presence of a catalytic amount of cesium carbonate (Cs2CO3) in chloroform at RT afforded methyl 4-(N-(trifluoromethoxy)acetamido)benzoate (2a). This intermediate was then converted to the final product methyl 4-acetamido-3-(trifluoromethoxy)benzoate (3a) in nitromethane at 120 &#176;C. This procedure is general and can be applied to the synthesis of a broad spectrum of ortho-trifluoromethoxylated aniline derivatives, which could serve as useful synthetic building blocks for the discovery and development of new pharmaceuticals, agrochemicals, and functional materials.

Protocol for the Synthesis of Ortho-trifluoromethoxylated Aniline Derivatives

An operationally simple procedure for the synthesis of ortho-trifluoromethoxylated aniline derivatives via a two-step sequence of O-trifluoromethylation of N-aryl-N-hydroxyacetamide followed by thermally induced intramolecular OCF3-migration is reported.

协议的合成<em&gt;邻</em&gt; -trifluoromethoxylated苯胺类化合物

Molecules bearing trifluoromethoxy (OCF3) group often show desired pharmacological and biological properties. However, facile synthesis of ...

Synthesis and Characterization of Supramolecular Colloids

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

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

超分子胶体的合成与表征

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

Synthesis of Protein Bioconjugates via Cysteine-maleimide Chemistry

The chemical linking or bioconjugation of proteins to fluorescent dyes, drugs, polymers and other proteins has a broad range of applications, such as the development of antibody drug conjugates (ADCs) and nanomedicine, fluorescent microscopy and systems chemistry. For many of these applications, specificity of the bioconjugation method used is of prime concern. The Michael addition of maleimides with cysteine(s) on the target proteins is highly selective and proceeds rapidly under mild conditions, making it one of the most popular methods for protein bioconjugation.
We demonstrate here the modification of the only surface-accessible cysteine residue on yeast cytochrome c with a ruthenium(II) bisterpyridine maleimide. The protein bioconjugation is verified by gel electrophoresis and purified by aqueous-based fast protein liquid chromatography in 27% yield of isolated protein material. Structural characterization with MALDI-TOF MS and UV-Vis is then used to verify that the bioconjugation is successful. The protocol shown here is easily applicable to other cysteine - maleimide coupling of proteins to other proteins, dyes, drugs or polymers.

Synthesis of Protein Bioconjugates via Cysteine-maleimide Chemistry

This protocol details the important steps required for the bioconjugation of a cysteine containing protein to a maleimide, including reagent purification, reaction conditions, bioconjugate purification and bioconjugate characterization.

蛋白质生物缀合物的合成<em&gt;通过</em&gt;半胱氨酸马来酰亚胺化学

The chemical linking or bioconjugation of proteins to fluorescent dyes, drugs, polymers and other proteins has a broad range of applications, such as the ...

Hydroquinone Based Synthesis of Gold Nanorods

Gold nanorods are an important kind of nanoparticles characterized by peculiar plasmonic properties. Despite their widespread use in nanotechnology, the synthetic methods for the preparation of gold nanorods are still not fully optimized. In this paper we describe a new, highly efficient, two-step protocol based on the use of hydroquinone as a mild reducing agent. Our approach allows the preparation of nanorods with a good control of size and aspect ratio (AR) simply by varying the amount of hexadecyl trimethylammonium bromide (CTAB) and silver ions (Ag+) present in the "growth solution". By using this method, it is possible to markedly reduce the amount of CTAB, an expensive and cytotoxic reagent, necessary to obtain the elongated shape. Gold nanorods with an aspect ratio of about 3 can be obtained in the presence of just 50 mM of CTAB (versus 100 mM used in the standard protocol based on the use of ascorbic acid), while shorter gold nanorods are obtained using a concentration as low as 10 mM.

This paper describes a protocol for the synthesis of gold nanorods, based on the use of hydroquinone as reducing agent, plus the different mechanisms for controlling their size and aspect ratio.

金纳米棒基于对苯二酚合成

Gold nanorods are an important kind of nanoparticles characterized by peculiar plasmonic properties. Despite their widespread use in nanotechnology, the ...

Controlled Synthesis and Fluorescence Tracking of Highly Uniform Poly(N-isopropylacrylamide) Microgels

Stimuli-sensitive poly(N-isopropylacrylamide) (PNIPAM) microgels have various prospective practical applications and uses in fundamental research. In this work, we use single particle tracking of fluorescently labeled PNIPAM microgels as a showcase for tuning microgel size by a rapid non-stirred precipitation polymerization procedure. This approach is well suited for prototyping new reaction compositions and conditions or for applications that do not require large amounts of product. Microgel synthesis, particle size and structure determination by dynamic and static light scattering are detailed in the protocol. It is shown that the addition of functional comonomers can have a large influence on the particle nucleation and structure. Single particle tracking by wide-field fluorescence microscopy allows for an investigation of the diffusion of labeled tracer microgels in a concentrated matrix of non-labeled microgels, a system not easily investigated by other methods such as dynamic light scattering.

Controlled Synthesis and Fluorescence Tracking of Highly Uniform PolyN-isopropylacrylamide Microgels

Non-stirred precipitation polymerization provides a rapid, reproducible prototyping approach to the synthesis of stimuli-sensitive poly(N-isopropylacrylamide) microgels of narrow size distribution. In this protocol synthesis, light scattering characterization and single particle fluorescence tracking of these microgels in a wide-field microscopy setup are demonstrated.

可控合成和高度统一聚荧光追踪（<em&gt;ñ</em&gt; -isopropylacrylamide）微凝胶

Stimuli-sensitive poly(N-isopropylacrylamide) (PNIPAM) microgels have various prospective practical applications and uses in fundamental research. In this ...

Facet-to-facet Linking of Shape-anisotropic Colloidal Cadmium Chalcogenide Nanostructures

Here, we describe a protocol that allows for shape-anisotropic cadmium chalcogenide nanocrystals (NCs), such as nanorods (NRs) and tetrapods (TPs), to be covalently and site-specifically linked via their end facets, resulting in polymer-like linear or branched chains. The linking procedure begins with a cation-exchange process in which the end facets of the cadmium chalcogenide NCs are first converted to silver chalcogenide. This is followed by the selective removal of ligands at their surface. This results in cadmium chalcogenide NCs with highly reactive silver chalcogenide end facets that spontaneously fuse upon contact with each other, thereby establishing an interparticle facet-to-facet attachment. Through the judicious choice of precursor concentrations, an extensive network of linked NCs can be produced. Structural characterization of the linked NCs is carried out via low- and high-resolution transmission electron microscopy (TEM), as well as energy-dispersive X-ray spectroscopy, which confirm the presence of silver chalcogenide domains between chains of cadmium chalcogenide NCs.

A protocol detailing how shape-anisotropic colloidal cadmium chalcogenide nanocrystals can be covalently linked via their end facets is presented here.

形状-各向异性胶体镉硫纳米结构的 Facet-to-facet 连接

Here, we describe a protocol that allows for shape-anisotropic cadmium chalcogenide nanocrystals (NCs), such as nanorods (NRs) and tetrapods (TPs), to be ...

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 ...