Name: phase diagram characterization using magnetic beads as liquid carriers
Uploaded: 2015-09-04T13:00:00.000+00:00
Duration: 12 min 37 s
Description: Watch this Scientific Journal Video about Phase Diagram Characterization Using Magnetic Beads as Liquid Carriers at JoVE.com

The authors acknowledge many useful discussions with M. Caggioni and support from Proctor and Gamble in the form of an internship for NAB.

在设备1.准备一次性使用的材料<ol><li>管的制备<ol><li>切管分为15厘米的段。管具有1.6毫米内径和3.2毫米的外径。 </li><li>杭管段垂直使用磁带。将纸巾筒下方，以收集多余的含氟聚合物溶液。 </li><li>注入100微升含氟聚合物溶液到使用注射器，使得其将与在内壁全周接触每个管段的顶部开口。 </li><li>允许管段代替悬挂1小时以除去含氟聚合物溶液过量。 </li><li>清理出从管未滴出的底面侧的含氟聚合物溶液。从悬挂位置拆下油管和处置纸巾。 </li><li>地方管道段到烘箱中在100℃下进行1小时退火该氟聚合物涂覆层。 </li><li>从烤箱中取出管段。使用镊子，作为管赛格将会进行热。 </li></ol></li><li>稀释磁珠溶液的制备<ol><li>计算以获得所需的结转量，如通过结转量和MB 图2质量所示之间的关系来确定所需的磁珠浓度。 注:原MB的溶液具有1克在50毫升溶液MB的。考虑20微升的测试腔容积，稀释用蒸馏水原始MB的溶液至6:4的比例（MB溶液:水）精制，得到的〜0.4微升结转量。调整时，不同的结转量所需的稀释比例。 </li><li>放置20ml的样品瓶到微平衡。零平衡。 </li><li>搅动磁珠溶液的容器中，然后用微量移液器撤回0.6毫升</li><li>分装移液溶液进入资产负债样品瓶。 </li><li>分配0.4毫升蒸馏水放入样品瓶。 </li></ol></li><li>荧光染料升iquid准备<ol><li>通过涡旋将溶液1分钟溶解染料入DI水中的2重量％。 </li></ol></li></ol> 2.准备荧光实验实验装置<ol><li>制备管设备。 <ol><li>插入阴路厄锁定连接器在管线上的一端。 </li><li>将管放入一个路厄锁注射器，其具有3 ml的体积和0.1ml毕业。 </li><li>将注射器插入注射器泵，并设置进料速率为2毫升/小时。 </li><li>为准确地插入的液体进入管道，使用注射泵撤回包含磁性珠和荧光染料的溶液。 </li><li>刀片20微升磁珠溶液进入管中，使用注射泵撤出。这种液体段被称为测试室（试验室容积可以根据实验而变化）。涡容器与磁珠溶液1分钟，然后用手在搅动<html>停药周期形成均匀MB分散体。 </li><li>后测试室液体的插入结束后，撤回6微升的空气进入管。空气的这种量将在后面形成在两液体段之间的阀。 </li><li>后空气间隙插入完成，开始撤出180微升液体与荧光染料。这种液体段被称为储。储集器容积可以根据实验而变化。更大的容器体积是有利的，以减少染料浓度的变化。 </li><li>放置一个第二阴鲁尔锁连接器到管的另一端。 </li><li>从注射器取下管装置。 </li><li>放置鲁尔锁帽上的装置的两端。 </li></ol></li><li>光学设置的荧光实验<ol><li>打开连接于倒置显微镜的所有组件。 </li><li>打开电脑，打开显微镜成像软件。 </li></ol></li></ol>对于荧光实验"&gt; 3。实验步骤<ol><li>以试验室和水库的初始荧光强度测量使用倒置显微镜。当分析样品的荧光，确保该焦点是在中心位置（在x和y方向上）的管内的液体一段。在数据表格中记录测量。 </li><li>放置设备通过立方体磁铁，使得磁珠所有分离到一个区域中的测试室的顶部。通过移动设备在磁铁（〜10秒）的顶部传送珠到储存器。 1英寸的钕磁铁的立方体是等级N48与45.6公斤拉力。 </li><li>一旦磁珠簇通过空气间隙并进入储存器传送，通过将装置在磁铁的顶部和旋转，以释放群集内被捕获的液体搅动磁珠。继续的磁珠搅拌直至贮存的同质化已经完成（〜30-45秒）。 </li><li>放置设备上的磁铁，使得磁珠在水库所有分离到一个区域的顶部。传送磁珠簇回测试室中。 </li><li>一旦簇到达测试室，通过将装置在磁铁的顶部和旋转以释放内被困荧光液体搅动磁珠。继续的磁珠搅拌直至试验室的均化已完成（〜30-45秒）。 </li><li>取这两个测试室和储存器的荧光强度测量使用倒置显微镜。在数据表格中记录测量。 </li><li>步骤3.2-3.6重复直到两个液体段收敛到类似的荧光强度（〜100个循环）。 </li></ol>荧光数据的4数值分析<ol><li>与荧光强度数据存储到电子表格中，使用MATLAB进行数值分析。 </li><li> DERIVë方程来计算在这两个贮存器和测试室荧光强度的理论值。包括下列方程化为一个MATLAB脚本文件: 其中I是荧光强度（AU），V是体积（微升）中，n是转移的数目，R为水库，T是测试室，和C是结转。 </li><li>使用MATLAB，生成图表和分析，以确定结转量在所有实验。使用这个数据，以产生图2。 </li></ol> 5.准备表面活性剂实验实验装置<ol><li>制备管设备。 <ol><li>插入阴鲁尔锁到管的一端。 </li><li>将管放入一个路厄锁注射器。 </li><li>将注射器插入注射器泵，并设置进料速率为2毫升/小时。 </li><li>为了准确地插入液体进入管道，使用注射泵撤回含有磁珠和苏解rfactant。 </li><li>将20微升磁珠解决方案为使用注射泵抽取管。这种液体段被称为测试室（试验室容积可以根据实验而变化）。搅动容器中撤出周期用手磁珠溶液中以形成均匀的MB的分散体。 </li><li>后测试室液体的插入结束后，撤回6微升的空气进入管。空气的这种体积将在后面被称作气隙。 </li><li>经过空气间隙插入完成，开始180微升纯C12E5表面活性剂撤出。这将在后面被称作储存器。 </li></ol></li><li>光学设置为表面活性剂的实验。 <ol><li>移动注射器泵与管装置，使得测试腔室与磁珠在焦点与立体显微镜。 </li><li>放置偏振膜的片材上的LED光源的上方。滑动LED光源附着到管下方注射泵。 </li><li>附加另一个偏光片用胶带立体显微镜的镜头。可以肯定的，这两个偏振膜具有90度彼此偏移。 </li><li>安装的CCD（电荷耦合器件）照相机的立体显微镜。将相机连接到电脑，并打开图像处理软件。 </li></ol></li></ol>为表面活性剂实验6.实验步骤<ol><li>广场旁边的试验室立方体磁铁在磁铁安装在支架上。 </li><li>一旦磁珠形成集群，开始以2毫升/小时的进料速率，使得磁珠群集从测试室移动，穿过气隙，并进入表面活性剂的储存室中的管泵送液体。 </li><li>一旦磁珠组达到该储存室的中点，停止对注射器泵泵送。 </li><li>移动立方体磁铁远离管，允许磁珠以分离次减少被困在磁珠簇的液体的扩散时间。 </li><li>观看电脑屏幕，通过不同阶段来观察H 2 O / C12E5混合周期。 </li><li>一旦液体的扩散和相变完成时，将磁铁回其原目的地由储所以磁珠组建成群集。 </li><li>使用注射泵，使得磁珠簇被从表面活性剂贮器传送，穿过气隙，并撤销所述的液体返回到H 2 O的测试室。 </li><li>一旦磁珠组达到该试验室的中点，停止对注射器泵泵送。 </li><li>移动立方体磁铁远离管。这将允许磁珠来分离和将有助于减少被困在磁珠簇的液体的扩散时间。 </li><li>观看电脑屏幕，通过不同阶段来观察H 2 O / C12E5混合周期。 </l我&gt; <li>一旦液体的扩散和相变完成时，将磁铁回到其由试验室前目的地，以便所述磁珠组建成群集。 </li><li>重复步骤6.2-6.11，直到试验室显示的相变。 </li></ol>

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The authors have no competing financial interests.

在对于相图调查最常用的技术，具有不同组成和比率多个样品需要准备和必须达到热力学平衡，导致一个冗长的过程，并一个显著量的材料。有些挑战可以通过DIT使用平面毛细管和红外分析方法来解决（扩散界面运输）的方法，但没有人可以解决与低成本的投资都提出了挑战。 使用磁珠用作液体载体在此微流控"实验室中管"方法的可行性证实为使用检测相邻液体段之间的相变。此方法允许精确地组合物的变化，这也可以使用示出的数值分析技术是预定的。查看在水表面活性剂体系现场的变化，同时使微乎其微改建为化学化妆的能力被证明是该装置的宝贵财富。在工业中用于分析相变目前的技术有关联的一些不良的方面。成本永远是一个问题，而且具有实验过程中使用这样小体积的昂贵的化学品如C12E5的能力肯定是一个优势。同样地，当减少样本大小，等待时间为扩散过程发生时显著降低。的H 2 O / C12E5系统是相当复杂的，可能需要较长的时间来解决成特定阶段时其组成被改变。这些冗长的扩散时间可能似乎是不希望的，但它比较的应用在工业方法扩散时间时，它被迅速地看作是在分析复杂系统的组合物的渐进步骤。 当分析二元体系的相变，或任何数量的混合的化学物质，它是非常重要的有被使用在该方法中适当的精度。花了很多时间寻找结转量与马之间的关系gnetic珠质量。有几个不同的变量，如磁珠簇的孔隙率，测试腔室体积对储集器容积，和磁珠簇质量，进行了研究，使我们能够合并不同的数据集，并创建一个模型。在此过程中，大的外卖是结转量和磁珠簇质量之间所获得的线性关系。我们发现结转量是珠〜2至3微升/毫克。当然，这种关系不与测试室和储卷关联，允许更复杂的实验方法。意，由于结转量几乎充当取决于磁珠质量恒定，液体体积在系统中可以预先确定，从而创建所需步骤改变两种液体的组合物。这可以派上用场，当用户希望看到成分波动的任何地方，从0.25％到10％。 该协议提供了很高的可行性探索PHASE图上构成小样本量和精细的分辨率。然而，目前的协议仍需要几分钟单次传输，导致对完整的相图调查天。这一限制可以通过使用更薄的管直径或机械致动引起的外部磁场的变化来克服。

为1微米的直径的数量级上的磁珠（MBS）已用于1,2-经常在微流体为基础的应用，尤其是用于生物医学装置。在这些设备中，宏模块都提供了功能，例如细胞和核酸分离，造影剂，和药物递送，仅举几例。外部（磁场）控制墨滴为基础的微流控相结合，使3个控制使用小体积（&lt;100 NL）免疫测定。中型企业也表明承诺用于液体处理4时。这种方法使用的MB对的管通过空气阀隔开内输送液体段之间的生物分子。这种方法是不一样强大其它更复杂的实验片上的设备出现在过去，但它是更简单，确实提供了一种处理液体微升尺寸的卷的能力。类似的方法最近有报道5通过哈塞尔顿小组，并应用于生物医学检测。 一个这种装置的最重要的方面是由表面张力控制用空气阀所提供的液体段的分离。的液体微升体积连接到MB被通过使用外部施加的磁场的液体段之间这个空气间隙传送。微粒的MB（从〜直径0.4-7微米，平均1.9微米）下的外部磁场的影响创建内捕获液体中的微多孔群集。这种液体截留的强度足以从一个储到下运送的MB时承受表面张力的力。通常情况下，这种效果是不希望的，因为大多数的方法只需要包含在液体6中的特定分子（例如生物标志物）的传输。然而，如在我们的工作中可以看出，这种效果可以用于成为该装置的一个有利的方面。 我们已经利用这种"实验中筒"方法， 在图1中示意性地示出，用于分析相图中的二进制材料系统。该表面活性剂C12E5已被选作鉴定的主要焦点，因为它被广泛用于工业应用，如药品，食品，化妆品等。特别地，在H 2 O / C12E5二元体系进行了研究，因为它提供了一个丰富组阶段的探索。我们的重点是该化学品混合物，即一定浓度7-9下转变为液晶相的一个具体方面。这种转变是很容易地在我们的设备通过将在光学显微镜研究偏振器以突出相边界处观察到。 能够映射相图是研究以了解涉及相转变10的动力学的非常重要的领域。精确地确定表面活性剂的用溶剂的相互作用的能力第二其它组分是至关重要的，因为它们的复杂性和许多不同的阶段11。许多其它技术先前已经用于表征相变。传统方法涉及制备许多样品，每个包括不同浓度的，并允许他们平衡，这需要冗长的处理时间和高量的样品体积的。然后，样品典型地通过光学方法如扩散界面传输（DIT），它提供了高分辨率的这样的表面活性剂组合物12,13进行分析。类似于我们已经利用的方法中，在DIT方法使用偏振光图像上不同的相的边界。

<table><tbody><tr><td>AccuBead</td><td>Bioneer Inc.</td><td>TS-1010-1</td><td>Magnetic beads</td></tr><tr><td>C12E5 Surfactant</td><td>Sigma-Aldrich</td><td>76437</td><td></td></tr><tr><td>Thermo Scientific Nalgene 890</td><td>Fisher Scientific</td><td>14176178</td><td></td></tr><tr><td>Cube Magnet</td><td>Apex Magnets</td><td>M1CU</td><td></td></tr><tr><td>Polarizer Film</td><td>Edmund Optics</td><td>38-493</td><td></td></tr><tr><td>Teflon AF</td><td>Dupont</td><td>400s1-100-1</td><td>Fluoropolymer solution</td></tr><tr><td>Keyacid Red Dye</td><td>Keystone</td><td>601-001-49</td><td>Fluorescent dye</td></tr><tr><td>Luer-Lock</td><td>Cole-Parmer</td><td>T-45502-12</td><td>Female</td></tr><tr><td>Luer-Lock</td><td>Cole-Parmer</td><td>T-45502-56</td><td>Male</td></tr><tr><td>Syringe</td><td>Fisher Scientific</td><td>14-823-435</td><td>3 ml</td></tr><tr><td>Syringe Pump</td><td>Stoelting</td><td>53130</td><td></td></tr><tr><td>Stereo Microscope</td><td>Nikon</td><td>SMZ-2T</td><td></td></tr><tr><td>Inverted Microscope</td><td>Nikon</td><td>Eclipse Ti-U</td><td>The filter cube used had an excitation wavelength range from 540-580 nm and a dichroic mirror at 585 nm, allowing for photoemission ranging from 593-668 nm.</td></tr><tr><td>Balance</td><td>Denver Instruments&amp;nbsp;</td><td>PI-225D</td><td></td></tr><tr><td>Microscope-Mounted Camera</td><td>Motic</td><td>5000</td><td></td></tr></tbody></table>

phase diagram characterization using magnetic beads as liquid carriers

磁珠〜1.9微米的平均直径分别用于输送的连续液段之间的液体微升体积用管为调查这些液体段的相变的目的。磁珠用磁铁，允许珠弥合相邻液体段之间的空气阀是从外部进行控制。疏水性涂层施加到管的内表面上，以提高两液体段之间的分离。施加的磁场形成的磁性珠粒的聚集体簇，即称为结转体积群集内捕获了一定量的液体。将荧光染料加到一种液体段，后面是一系列的液体转移，然后改变的荧光强度在邻近液体一段。基于测得的荧光强度变化的数值分析，每磁珠质量的结转量已经发现为〜2至3微升/毫克。允许使用几百微升比较小的液体段的这种少量的液体，提高了装置的可行性实验室中筒的方法。施加小的组成变化在液体体积的这种技术被用于分析水和表面活性剂C12E5（五乙二醇单十二烷基醚）之间的二元相图，导致更快的分析更小的样品体积比常规方法。

使用实验室中管的方法用于输送液体微升容积量与磁珠一起MATLAB进行数值分析，平均液体结转卷，磁珠质量的函数，被发现（图2）。更高质量的磁珠提供在2-3微升/毫克的速率更高的结转量。实验设置（图1）被用来观察的 H 2 O / C12E5二元体系内的相变。由于H 2 O / C12E5系统是公知的，有许多不同的阶段，它可以在图3B中可以看出，它作为参考的适当点，以进一步表征我们的设备。的虚线图3B示出了实验，在20℃的〜进行的标称温度。反应小心地从短次观察到的，如0到90秒看到在图3C中，以更长的时间，例如1.5至25分钟＆＃160; 如图 4所示的L 1至Lα相变化被用于核查结转量在H 2 O / C12E5二元体系。短期观察表明相位转变成各种液晶相时进行水被转移到C12E5表面活性剂室中。然而，这种相变可以是颞作为扩散继续在液体腔达到均匀的状态。最终，多个传输将导致永久性的相变，如图5B所示。尽管疏水性涂层施加到内壁的管的，我们的装置的一个关心的是变化结转体积由于液体附着于内壁的管作为较大体积泵送回的往复。反驳这一问题的方法之一就是从设备中取出磁珠并进行同样的实验，就好像在磁珠仍然存在。这将消除结转控制音量，使我们能够观察化学成分，从这个不需要的液体传输发起的任何影响。甲看出，当磁珠已到位（ 图5中的A，B）时，他们正在从系统中（图5 C，D）除去对相变化的结果进行了比较。幸运的是，这种担心被发现时相比，结转量是微不足道的。 <img alt="图1" src="/files/ftp_upload/52957/52957fig1.jpg" /> 图1实验装置和光管的示意图用于表示一个由空气阀隔开的两个液体段。转载（改编）与Blumenschein，N.，汉族，博士，Caggioni，M.，Steckl，A磁许可在微流控芯片实验室中管法颗粒的液体载体为了检测相位变化。 ACS应用材料与界面。 6（11），8066-8072，DOI:10.1021 / am502845p（2014）。版权所有2014年美国化学学会。 <a href="https://www.jove.com/files/ftp_upload/52957/52957fig1large.jpg" target="_blank">请点击此处查看该图的放大版本。</a> <img alt="图2" src="/files/ftp_upload/52957/52957fig2.jpg" /> 每次传输与磁珠质量图2.平均液体结转量。阴谋利用MATLAB数值分析。转载（改编）与Blumenschein，N.，汉族，博士，Caggioni，M.，Steckl，在微流控芯片实验室中管方法要检测相变A.磁性粒子液体载体许可。 ACS应用材料与界面。 6（11），8066-8072，DOI:10.1021 / am502845p（2014）。版权所有2014年美国化学学会。 <a href="https://www.jove.com/files/ftp_upload/52957/52957fig2large.jpg" target="_blank">请点击此处查看该图的放大版本。</a> 图3.（A）实验室中管实验装置。 （B）相变曲线的H 2 O / C12E5双星系统。的H（C）观测到的相变2 O / C12E5从0到90秒。转载（改编）与Blumenschein，N.，汉族，博士，Caggioni，M.，Steckl，在微流控芯片实验室中管方法要检测相变A.磁性粒子液体载体许可。 ACS应用材料与界面。 6（11），8066-8072，DOI:10.1021 / am502845p（2014）。版权所有2014年美国化学学会。 <a href="https://www.jove.com/files/ftp_upload/52957/52957fig3large.jpg" target="_blank">请点击此处查看该图的放大版本。</a> <img alt="图4" src="/files/ftp_upload/52957/52957fig4.jpg" /> 图4。的 H 2 O / C12E5超过1.5至25分钟期间的相位变化。转载（适于）与来自Blumenschein，N.，韩，D。，Caggioni，M。，Steckl，在微流体实验室A.磁颗粒用作液体载体的权限-in-管方法要检测相位变化。 ACS应用材料与界面。 6（11），8066-8072，DOI:10.1021 / am502845p（2014）。版权所有2014年美国化学学会。 <a href="https://www.jove.com/files/ftp_upload/52957/52957fig4large.jpg" target="_blank">请点击此处查看该图的放大版本。</a> <img alt="图5" src="/files/ftp_upload/52957/52957fig5.jpg" /> 图5.两个设备制备1的测试腔初始浓度:1 的 H 2 O / C12E5和储层含纯C12E5。利用〜0.2毫克珠初始条件（A）至6转让（B），从L1样品过渡到Lα阶段。在座升降MB的NCE，无相变看出（C，D）。在25℃下进行试验。转载（改编）与Blumenschein，N.，汉族，博士，Caggioni，M.，Steckl，在微流控芯片实验室中管方法要检测相变A.磁性粒子液体载体许可。 ACS应用材料与界面。 6（11），8066-8072，DOI:10.1021 / am502845p（2014）。版权所有2014年美国化学学会。 <a href="https://www.jove.com/files/ftp_upload/52957/52957fig5large.jpg" target="_blank">请点击此处查看该图的放大版本。</a>

Watch this Scientific Journal Video about Phase Diagram Characterization Using Magnetic Beads as Liquid Carriers at JoVE.com

Phase Diagram Characterization Using Magnetic Beads as Liquid Carriers

Here, we present a protocol to investigate multi-component phase diagrams using externally controlled magnetic beads as liquid carriers in a lab-in-tube approach. This approach can aid in applications that seek to gather further information on phase change in complex liquid systems.

相图表征使用磁珠用作液体载体

Magnetic beads with ~1.9 &#181;m average diameter were used to transport microliter volumes of liquids between contiguous liquid segments with a tube for ...

phase-diagram-characterization-using-magnetic-beads-as-liquid-carriers

Nanyang Technological University

Research

JoVE Journal

Engineering

12.2K 次观看.  University of Cincinnati. Here, we present a protocol to investigate multi-component phase diagrams using externally controlled magnetic beads as liquid carriers in a lab-in-tube approach. This approach can aid in applications that seek to gather further information on phase change in complex liquid systems.

视频: Phase Diagram Characterization Using Magnetic Beads as Liquid Carriers

Sputter Growth and Characterization of Metamagnetic B2-ordered FeRh Epilayers

Chemically ordered alloys are useful in a variety of magnetic nanotechnologies. They are most conveniently prepared at an industrial scale using sputtering techniques. Here we describe a method for preparing epitaxial thin films of B2-ordered FeRh by sputter deposition onto single crystal MgO substrates. Deposition at a slow rate onto a heated substrate allows time for the adatoms to both settle into a lattice with a well-defined epitaxial relationship with the substrate and also to find their proper places in the Fe and Rh sublattices of the B2 structure. The structure is conveniently characterized with X-ray reflectometry and diffraction and can be visualised directly using transmission electron micrograph cross-sections. B2-ordered FeRh exhibits an unusual metamagnetic phase transition: the ground state is antiferromagnetic but the alloy transforms into a ferromagnet on heating with a typical transition temperature of about 380 K. This is accompanied by a 1% volume expansion of the unit cell: isotropic in bulk, but laterally clamped in an epilayer. The presence of the antiferromagnetic ground state and the associated first order phase transition is very sensitive to the correct equiatomic stoichiometry and proper B2 ordering, and so is a convenient means to demonstrate the quality of the layers that can be deposited with this approach. We also give some examples of the various techniques by which the change in phase can be detected.

A method to prepare epitaxial layers of ordered alloys by sputtering is described. The B2-ordered FeRh compound is used as an example, as it displays a metamagnetic transition that depends sensitively on the degree of chemical order and the exact composition of the alloy.

变磁B2有序化的FeRh外延层溅射生​​长和表征

Chemically ordered alloys are useful in a variety of magnetic nanotechnologies. They are most conveniently prepared at an industrial scale using ...

科研

工程学

Frequency Mixing Magnetic Detection Scanner for Imaging Magnetic Particles in Planar Samples

The setup of a planar Frequency Mixing Magnetic Detection (p-FMMD) scanner for performing Magnetic Particles Imaging (MPI) of flat samples is presented. It consists of two magnetic measurement heads on both sides of the sample mounted on the legs of a u-shaped support. The sample is locally exposed to a magnetic excitation field consisting of two distinct frequencies, a stronger component at about 77 kHz and a weaker field at 61 Hz. The nonlinear magnetization characteristics of superparamagnetic particles give rise to the generation of intermodulation products. A selected sum-frequency component of the high and low frequency magnetic field incident on the magnetically nonlinear particles is recorded by a demodulation electronics. In contrast to a conventional MPI scanner, p-FMMD does not require the application of a strong magnetic field to the whole sample because mixing of the two frequencies occurs locally. Thus, the lateral dimensions of the sample are just limited by the scanning range and the supports. However, the sample height determines the spatial resolution. In the current setup it is limited to 2 mm. As examples, we present two 20 mm &#215; 25 mm p-FMMD images acquired from samples with 1 &#181;m diameter maghemite particles in silanol matrix and with 50 nm magnetite particles in aminosilane matrix. The results show that the novel MPI scanner can be applied for analysis of thin biological samples and for medical diagnostic purposes.

A scanner for imaging magnetic particles in planar samples was developed using the planar frequency mixing magnetic detection technique. The magnetic intermodulation product response from the nonlinear nonhysteretic magnetization of the particles is recorded upon a two-frequency excitation. It can be used to take 2D images of thin biological samples.

混频磁探测仪在平面样品成像磁性微粒

The setup of a planar Frequency Mixing Magnetic Detection (p-FMMD) scanner for performing Magnetic Particles Imaging (MPI) of flat samples is presented. ...

Phase Behavior of Charged Vesicles Under Symmetric and Asymmetric Solution Conditions Monitored with Fluorescence Microscopy

Phase-separated giant unilamellar vesicles (GUVs) exhibiting coexisting liquid-ordered and liquid-disordered domains are a common biophysical tool to investigate the lipid raft hypothesis. Numerous studies, however, neglect the impact of physiological solution conditions. On that account, the current work presents the effect of high-salinity buffer and trans-membrane solution asymmetry on liquid-liquid phase separation in charged GUVs grown from dioleylphosphatidylglycerol, egg sphingomyelin, and cholesterol. The effects were studied under isothermal and varying temperature conditions.
We describe equipment and experimental strategies applicable for monitoring the stability of coexisting liquid domains in charged vesicles under symmetric and asymmetric high-salinity solution conditions. This includes an approach to prepare charged multicomponent GUVs in high-salinity buffer at high temperatures. The protocol entails the option to perform a partial exchange of the external solution by a simple dilution step while minimizing the vesicle dilution. An alternative approach is presented utilizing a microfluidic device that allows for a complete external solution exchange. The solution effects on phase separation were also studied under varying temperatures. To this end, we present the basic design and utility of an in-house built temperature control chamber. Furthermore, we reflect on the assessment of the GUV phase state, pitfalls associated with it and how to circumvent them.

Experiments on phase separated giant unilamellar vesicles (GUVs) frequently neglect physiological solution conditions. This work presents approaches to study the effect of high-salinity buffer on liquid-liquid phase separation in charged multicomponent GUVs as a function of trans-membrane solution asymmetry and temperature.

用荧光显微镜监测对称和非对称溶液条件下带电泡的相行为

Phase-separated giant unilamellar vesicles (GUVs) exhibiting coexisting liquid-ordered and liquid-disordered domains are a common biophysical tool to ...

化学

Fabrication Procedures and Birefringence Measurements for Designing Magnetically Responsive Lanthanide Ion Chelating Phospholipid Assemblies

Bicelles are tunable disk-like polymolecular assemblies formed from a large variety of lipid mixtures. Applications range from membrane protein structural studies by nuclear magnetic resonance (NMR) to nanotechnological developments including the formation of optically active and magnetically switchable gels. Such technologies require high control of the assembly size, magnetic response and thermal resistance. Mixtures of 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) and its lanthanide ion (Ln3+) chelating phospholipid conjugate, 1,2-dimyristoyl-sn-glycero-3-phospho-ethanolamine-diethylene triaminepentaacetate (DMPE-DTPA), assemble into highly magnetically responsive assemblies such as DMPC/DMPE-DTPA/Ln3+ (molar ratio 4:1:1) bicelles. Introduction of cholesterol (Chol-OH) and steroid derivatives in the bilayer results in another set of assemblies offering unique physico-chemical properties. For a given lipid composition, the magnetic alignability is proportional to the bicelle size. The complexation of Ln3+ results in unprecedented magnetic responses in terms of both magnitude and alignment direction. The thermo-reversible collapse of the disk-like structures into vesicles upon heating allows tailoring of the assemblies&#39; dimensions by extrusion through membrane filters with defined pore sizes. The magnetically alignable bicelles are regenerated by cooling to 5 &#176;C, resulting in assembly dimensions defined by the vesicle precursors. Herein, this fabrication procedure is explained and the magnetic alignability of the assemblies is quantified by birefringence measurements under a 5.5 T magnetic field. The birefringence signal, originating from the phospholipid bilayer, further enables monitoring of polymolecular changes occurring in the bilayer. This simple technique is complementary to NMR experiments that are commonly employed to characterize bicelles.

Fabrication procedures for highly magnetically responsive lanthanide ion chelating polymolecular assemblies are presented. The magnetic response is dictated by the assembly size, which is tailored by extrusion through nanopore membranes. The assemblies&#39; magnetic alignability and temperature-induced structural changes are monitored by birefringence measurements, a complimentary technique to nuclear magnetic resonance and small angle neutron scattering.

设计磁响应稀土离子螯合磷脂组件的制备方法及双折射测量

Bicelles are tunable disk-like polymolecular assemblies formed from a large variety of lipid mixtures. Applications range from membrane protein structural ...

Methods of Ex Situ and In Situ Investigations of Structural Transformations: The Case of Crystallization of Metallic Glasses

We demonstrate the use of two nuclear-based analytical methods that can follow the modifications of microstructural arrangement of iron-based metallic glasses (MGs). Despite their amorphous nature, the identification of hyperfine interactions unveils faint structural modifications. For this purpose, we have employed two techniques that utilize nuclear resonance among nuclear levels of a stable 57Fe isotope, namely M&#246;ssbauer spectrometry and nuclear forward scattering (NFS) of synchrotron radiation. The effects of heat treatment upon (Fe2.85Co1)77Mo8Cu1B14 MG are discussed using the results of ex situ and in situ experiments, respectively. As both methods are sensitive to hyperfine interactions, information on structural arrangement as well as on magnetic microstructure is readily available. M&#246;ssbauer spectrometry performed ex situ describes how the structural arrangement and magnetic microstructure appears at room temperature after the annealing under certain conditions (temperature, time), and thus this technique inspects steady states. On the other hand, NFS data are recorded in situ during dynamically changing temperature and NFS examines transient states. The use of both techniques provides complementary information. In general, they can be applied to any suitable system in which it is important to know its steady state but also transient states.

Methods of Ex Situ and In Situ Investigations of Structural Transformations: The Case of Crystallization of Metallic Glasses

Here, we present a protocol to describe ex situ and in situ investigations of structural transformations in metallic glasses. We employed nuclear-based analytical methods which inspect hyperfine interactions. We demonstrate the applicability of M&#246;ssbauer spectrometry and nuclear forward scattering of synchrotron radiation during temperature-driven experiments.

结构转换的原位和原位研究方法: 金属玻璃结晶的实例

We demonstrate the use of two nuclear-based analytical methods that can follow the modifications of microstructural arrangement of iron-based metallic ...

Measuring Magnetically-Tuned Ferroelectric Polarization in Liquid Crystals

Materials showing coupling phenomena between magnetism and (ferro)electricity, i.e., magnetoelectric effects, have attracted a great deal of attention due to their potential applications for future device technologies such as sensors and storage. However, conventional approaches, which usually utilize materials containing magnetic metal ions (or radicals), have a major problem: only a few materials have been found to show the coupling phenomena at room temperature. Recently, we proposed a new approach to achieve room-temperature magnetoelectrics. In contrast to conventional approaches, our alternative proposal focuses on a completely different material, a &#34;liquid crystal&#34;, free from magnetic metal ions. In such liquid crystals, a magnetic field can be utilized to control the orientational state of constituent molecules and the corresponding electric polarization through magnetic anisotropy of the molecules; it is an unprecedented mechanism of the magnetoelectric effect. In this context, this paper provides a protocol to measure ferroelectric properties induced by a magnetic field, that is, the direct magnetoelectric effect, in a liquid crystal. With the method detailed here, we successfully detected magnetically-tuned electric polarization in the chiral smectic C phase of a liquid crystal at room temperature. Taken together with the flexibility of constituent molecules, which directly affects the magnetoelectric responses, the introduced method will serve to allow liquid crystal cells to acquire more functions as room-temperature magnetoelectrics and associated optical materials.

In this report, we present a protocol to examine direct magnetoelectric effects, i.e., induction of ferroelectric polarization by applying magnetic fields, in liquid crystals. This protocol provides a unique approach, supported by the softness of liquid crystals, to achieve room-temperature magnetoelectrics.

液晶中磁调谐铁电极化的测量

Materials showing coupling phenomena between magnetism and (ferro)electricity, i.e., magnetoelectric effects, have attracted a great deal of attention due ...

Stable Aqueous Suspensions of Manganese Ferrite Clusters with Tunable Nanoscale Dimension and Composition

Manganese ferrite clusters (MFCs) are spherical assemblies of tens to hundreds of primary nanocrystals whose magnetic properties are valuable in diverse applications. Here we describe how to form these materials in a hydrothermal process that permits the independent control of product cluster size (from 30 to 120 nm) and manganese content of the resulting material. Parameters such as the total amount of water added to the alcoholic reaction media and the ratio of manganese to iron precursor are important factors in achieving multiple types of MFC nanoscale products. A fast purification method uses magnetic separation to recover the materials making production of grams of magnetic nanomaterials quite efficient. We overcome the challenge of magnetic nanomaterial aggregation by applying highly charged sulfonate polymers to the surface of these nanomaterials yielding colloidally stable MFCs that remain non-aggregating even in highly saline environments. These non-aggregating, uniform, and tunable materials are excellent prospective materials for biomedical and environmental applications.

We report a one-pot hydrothermal synthesis of manganese ferrite clusters (MFCs) that offers independent control over material dimension and composition. Magnetic separation allows rapid purification while surface functionalization using sulfonated polymers ensures the materials are non-aggregating in biologically relevant medium. The resulting products are well positioned for biomedical applications.

具有可调纳米尺度尺寸和成分的锰铁氧体簇的稳定水悬浮液

Manganese ferrite clusters (MFCs) are spherical assemblies of tens to hundreds of primary nanocrystals whose magnetic properties are valuable in diverse ...

氧化还原活性 MOF 固态电化学的磁力表征

Magnetometric Characterization of Intermediates in the Solid-State Electrochemistry of Redox-Active Metal-Organic Frameworks

Electrochemical energy storage has been a widely discussed application of redox-active metal-organic frameworks (MOFs) in the past 5 years. Although MOFs show outstanding performance in terms of gravimetric or areal capacitance and cyclic stability, unfortunately their electrochemical mechanisms are not well understood in most cases. Traditional spectroscopic techniques, such as X-ray photoelectron spectroscopy (XPS) and X-ray absorption fine structure (XAFS), have only provided vague and qualitative information about valence changes of certain elements, and the mechanisms proposed based on such information are often highly disputable. In this article, we report a series of standardized methods, including the fabrication of solid-state electrochemical cells, electrochemistry measurements, the disassembly of cells, the collection of MOF electrochemical intermediates, and physical measurements of the intermediates under the protection of inert gases. By using these methods for quantitatively clarifying the electronic and spin state evolution within a single electrochemical step of redox-active MOFs, one can provide clear insight into the nature of electrochemical energy storage mechanisms not only for MOFs, but also for all other materials with strongly correlated electronic structures.

作者聚焦：氧化还原活性金属有机框架固态电化学中中间体的磁力表征  

Ex situ magnetic surveys can directly provide bulk and local information on a magnetic electrode to reveal its charge storage mechanism step by step. Herein, electron spin resonance (ESR) and magnetic susceptibility are demonstrated to monitor the evaluation of paramagnetic species and their concentration in a redox-active metal-organic framework (MOF).

氧化还原-活性金属-有机骨架固态电化学中中间体的磁力表征

Electrochemical energy storage has been a widely discussed application of redox-active metal-organic frameworks (MOFs) in the past 5 years. Although MOFs ...

相图表征使用磁珠用作液体载体

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变磁B2有序化的FeRh外延层溅射生长和表征

混频磁探测仪在平面样品成像磁性微粒

用荧光显微镜监测对称和非对称溶液条件下带电泡的相行为

设计磁响应稀土离子螯合磷脂组件的制备方法及双折射测量

结构转换的原位和原位研究方法: 金属玻璃结晶的实例

液晶中磁调谐铁电极化的测量

具有可调纳米尺度尺寸和成分的锰铁氧体簇的稳定水悬浮液

氧化还原-活性金属-有机骨架固态电化学中中间体的磁力表征

氧化还原-活性金属-有机骨架固态电化学中中间体的磁力表征

氧化还原-活性金属-有机骨架固态电化学中中间体的磁力表征

相图表征使用磁珠用作液体载体

摘要

探索更多视频

此视频中的章节

变磁B2有序化的FeRh外延层溅射生​​长和表征

混频磁探测仪在平面样品成像磁性微粒

用荧光显微镜监测对称和非对称溶液条件下带电泡的相行为

设计磁响应稀土离子螯合磷脂组件的制备方法及双折射测量

结构转换的原位和原位研究方法: 金属玻璃结晶的实例

液晶中磁调谐铁电极化的测量

具有可调纳米尺度尺寸和成分的锰铁氧体簇的稳定水悬浮液

氧化还原-活性金属-有机骨架固态电化学中中间体的磁力表征

氧化还原-活性金属-有机骨架固态电化学中中间体的磁力表征

氧化还原-活性金属-有机骨架固态电化学中中间体的磁力表征

变磁B2有序化的FeRh外延层溅射生长和表征