The authors thank Prof. Peter Imming and Diana M&#252;ller for synthesis of the Trityl spin probe and Prof. Sebastian Polarz, Martin Wessig and Andreas Schachtschneider for the synthesis of the porous materials. Financial support by the DFG (DR 743/7-1) and within the SPP 1570 is gratefully acknowledged.

注意:使用前请咨询所有相关的材料安全数据表（MSDS）。如果吞入或吸入酒精是有害的，它是易燃的。 1.优化的连续波（CW）EPR参数<ol><li>在1mM的浓度制备的乙醇IPSL的40微升（PA）。 </li><li>取吸管控制器和填充的毛细管与IPSL溶液至2厘米的填充高度。溶液1厘米进一步拉入毛细管使得存在的溶液下方的空气间隙。密封与毛细管密封胶两端的毛细血管。气隙可以防止密封剂的成分扩散到样品。 </li><li>以1cm从毛细管的上下端部的距离环绕毛细管约5厘米长的聚四氟乙烯（PTFE）胶带的两个条带。 </li><li>把毛细管导入的EPR样品管（4内径）。确保PTFE带保持毛细管固定在样品管的中心轴。推毛细管下降到样品管的底部。 </li><li>把样品到谐振器和中心谐振器内的自旋标记物溶液。 </li><li>调通过以下在光谱仪说明手册分光计为临界耦合。 </li><li>初步光谱仪设置<ol><li>使用微波频率设置中心场B使用下式 <img alt="式（1）" src="/files/ftp_upload/54335/54335eq1.jpg" /> 其中g≈2.003为不成对自由基在氮氧化物自旋标记的g因子的粗略估计，h是普朗克常数和μB是玻尔磁。 </li><li>建立一个新的实验"field_sweep"与磁场为横坐标，信号强度为纵坐标。使用下面的参数:Centerfield如在先前步骤中，扫描宽度计算值:400 G，modulati振幅:0.8 G，调制频率:100kHz，微波衰减30分贝点数:2048，扫描次数:1，扫描时间:80秒，时间常数:50毫秒。 </li><li>激活设置扫描模式。对于设置扫描时间常数，选择最低值，光谱仪的优惠。调节接收机增益的值，其中所显示的信号填充显示强度范围的80％，因此，即使有噪声没有数据点具有比最大的80％的较高的强度。禁用设置扫描之后。 </li><li>按"运行"按钮。 </li><li>读出的过零点，从得到的频谱的中心峰的字段值。中间字段设置为该值。 </li><li>就拿水平线工具，测量从点谱宽，其中最左边的峰值开始上升基线水平之上的地步，最右边的峰值返回到基线水平。 </li><li>设置扫描宽度的三倍光谱宽度。 </li></ol></li><li>重新计算谱仪参数<ol><li>计算扫描时间:扫描宽度/扫描速度。使用5 G /秒的扫描速度。 </li><li>计算数据点的最小数目:10 *扫描宽度/线条宽度。 </li><li>计算转换时间:扫描时间/数据点的数目。 </li><li>计算时间常数:0.1 *行宽*扫描时间/扫描宽度。 </li></ol></li><li>衡量一个饱和曲线，以确定最佳微波功率<ol><li>将微波衰减为10 dB，按步骤1.7.3描述调节接收机增益。 </li><li>设置微波衰减到50分贝，记录光谱。如果信噪比低于5:1，增加扫描次数。重复此步骤直到信噪比为5:1或更大。 </li><li>创建新的实验"饱和"使用磁场为横坐标1，微波功率为横坐标2和信号强度作为纵轴。从日复制所有设置E"field_sweep"的实验步骤1.9.2。为横坐标2，微波衰减的开始值设置为10分贝的增量的值为1 dB和点至41以覆盖范围为10分贝至50分贝数。运行实验。 </li><li>创建饱和曲线的电子表格。插入以dB微波衰减到第一列。 </li><li>计算出微波功率的平方根中的Au在与式第二列 <img alt="公式（2）" src="/files/ftp_upload/54335/54335eq2.jpg" /> 其中x是从第一塔以dB微波衰减。 </li><li>使用分光计软件来测量峰峰值为在实验中每个微波衰减的中心谱线的强度。编写强度到电子表格中的第三列。 </li><li>绘制对峰峰值强度（针对2栏第3栏）的微波功率的平方根以获得饱和曲线。 Inclu在德积原点（0,0）。 </li><li>识别饱和曲线的线性状态。最佳微波功率是最高的微波功率是仍处于线性状态。使用相应的衰减设置为所有进一步的实验。 </li></ol></li></ol> 2.确定磁场梯度强度和时间分辨率<ol><li>创建与磁场为横坐标1和信号强度作为纵轴分光计软件新的实验。使梯度线圈控制。 </li><li>从在1.8和1.9.8确定之前的实验复制所有光谱仪的设置。 </li><li>设置磁场梯度强度170克/厘米的朝上样品轴的方向。 </li><li>计算扫描宽度SW = SW 0 + FOV·G，其中SW 0是在1.8.4在不存在磁场梯度的确定的扫描宽度，FOV 是视场（2.5厘米）和G是磁场梯度强度。 </li><li>计算估计像素尺寸=线宽/ G，采用在不存在磁场梯度的记录在1.9.3频谱的线宽。 </li><li>计算扫描时间= SW /扫描速度。使用相同的扫描速度为1.8.1。 </li><li>计算需要使用更高的值的数据点的最小数量 我。N + 1 = 10 *扫描宽度/线宽 二，N 2 = 10 *视图/（G *像素大小）的领域。 </li><li>计算转换时间:扫描时间/数据点的数目。 </li><li>计算时间常数:0.1 *线宽*扫描时间/扫描宽度或更低。 </li><li>通过2.9设置2.3计算参数，并按下"运行"按钮。 </li><li>测量基准的噪声电平以及峰值强度的峰与垂直线工具的中心线。计算出的信噪比。 </li><li>如果信噪比低于5:1，加倍扫描数在光谱仪的参数的"扫描"面板，并重复步骤2.1.3至2.11。 </li></ol> 3.准备样本注意:戴安全防护眼镜。 注:请溶剂在任何时候都完全淹没气凝胶。参见图2的照片和示意图。 <ol><li>填充直径为10厘米，用乙醇（PA）的培养皿高达5mm的高度。 </li><li>把气凝胶入培养皿和圆柱形一块5毫米切断为1厘米的长度。 </li><li>准备一块热缩管的比所述气凝胶筒长约1厘米。 </li><li>使用玻璃管切刀突破200内径的样品管创建4个厘米长的两件。两件应该有两个开口端。 <br/&gt;注意:操作热风枪时，应戴防护眼镜和合适的手套。不要直接对皮肤或衣服气流和易燃材料保持它拿走。 </li><li>插入该样品管件5 mm深入热缩管的一端中的一个。使用加热枪小心加热热缩管的这一端，而不管的其余部分缩小。该热缩管现在应该固定在玻璃管中。 <ol><li>浸没在气凝胶的培养皿玻璃管和热缩管的这种组合。小心地从步骤3.2推片气凝胶到热缩管的开口端。 </li></ol></li><li>填用乙醇（PA）的试管至7厘米的高度。从培养皿转移样品放入试管。虽然这样做，确保热缩管的开口端是面向上方。确保气凝胶在乙醇中完全淹没。 </li><li>插入第二个4厘米长片从步骤3.4到热缩管的开放端的试样管。不适用的力，重力应该足以关闭气凝胶和样品管段之间的间隙。把试管用样品放入烧杯中。 </li><li>填写一个压力锅至少500毫升乙醇中并加入搅拌棒。 </li><li>把含在高压锅内脚架样品的烧杯中。 注意:执行通风橱内的下一步，继续戴安全防护眼镜。 </li><li>库克和搅拌样品在上述的磁力搅拌器环境压力1巴的压力设置。温度必须至少达到90℃。让它尽快达到的压力和压力阀释放乙醇蒸汽冷却。如果热缩套管没有缩水，重复此步骤。 注:立即清洁压力锅用水，以尽量减少乙醇对密封阀的作用。在这一点上，所制备的样品可以储存在乙醇塞弗拉尔个月。 </li></ol> 4.准备光谱仪<ol><li>创建使用磁场为横坐标1 2d的实验，时间为横坐标2和信号强度为纵坐标，以使得磁场扫描记录每个时间步长。使梯度线圈控制。 </li><li>测量之间的时间延迟设置为零。如在第2组点为时间轴的数量确定为20小时/扫描时间设置其他参数。设置微波桥每个切片扫描后执行微调。 </li><li>按照1.7节的步骤调整光谱仪的空谐振器。 </li></ol> 5.准备测量样本注意:此协议的唯一时间关键步骤是5.3至6.2，它是从与另外的自旋标记物，直到在光谱仪中的数据采集开始时的扩散过程的开始。执行这些步骤，而不会引入任何延误。 <ol><li>把一个手指在样品的顶部从第3保持乙醇溶液从底部流出。然后使用注射器从底部5毫米较低的采样管的移除一些乙醇和密封以管密封化合物这一目的。确保有2毫米的高度密封化合物上方的气泡。 </li><li>从除于3 mm只用巴斯德毛细吸管气凝胶上述气凝胶上述样品管中取出所有乙醇。 </li><li>注入20微升的自旋标记物溶液中乙醇对气凝胶的顶部。确保不上气凝胶的顶部创建一个气泡。标记当前时间作为扩散过程的开始。 </li><li>放置在样品中有4个内径的样品管中。使用PTFE带居中样本。 </li><li>使用毡尖笔在68毫米气凝胶的上边缘上方的位置来标记所述外样品管中。这有助于在谐振器正确地定心在样品和所说的C谐振器的输入气凝胶的上边缘低于1毫米。 </li></ol> 6.执行扩散实验<ol><li>放置在样品中的谐振器，以使从5.5对准与谐振器和调分光计为如在分光计的操作手册中描述了临界耦合的聚四氟乙烯支架的顶部标记。 </li><li>使用设置扫描模式，如1.7.3所述，而梯度线圈仍然关闭，设置接收机增益。 </li><li>启动已成立了第4节写下当前时间的实验。要么等待20小时的实验，以完成或停止实验时所记录的信号不超过4小时以上的过程中发生变化。保存结果。 </li></ol> 7.执行数据分析所需的附加实验注:扩散试验后直接和不与莫相同的样品进行实验，在7.1和7.2咏样品。 <ol><li>记录为反卷积点扩散函数<ol><li>从步骤1.7.2切换到"扫场"实验。复制在步骤6从实验的所有设置。 </li><li>记录的光谱和测量的信噪比。如果它小于20:1，增加扫描次数，并重复此工序。否则，保存光谱。 </li></ol></li><li>执行2D成像实验<ol><li>创建与磁场分光计新实验为横坐标1，磁场梯度为横坐标2的角度和信号强度作为纵轴。的参数从步骤6.成像平面设置于YZ平面，这是包括静态磁场B 0的方向和样品轴的平面复制。 </li><li>设置渐变方向到N = FOV /所需的像素尺寸或更高氮角度的数量。 </li><li>开始测量并保存结果。 </li><li>重复次7.1Ë步骤，并保存结果。 </li></ol></li><li>测量谐振器灵敏度分布<ol><li>通过重复步骤1.1至1.5制备在溶液旋探针的另一样品，但这次加入4厘米溶液进入毛细管代替2厘米。 </li><li>跟随在第2步骤记录的样品的光谱与样品轴的方向的磁场梯度。对于步进2.3，使用的角度为3厘米的字段。保存结果。 </li><li>重复测量在不存在磁场梯度的和保存的结果。 </li></ol></li></ol> 8.数据分析<ol><li>重建二维成像实验<ol><li>从装载7.2.3二维成像实验到光谱仪软件的主视窗。 </li><li>从装载7.2.4实验到光谱仪软件的二次视口。 </li><li>去处理&gt;变换&gt;解卷积，选择切片:所有并点击适用于执行反卷积。 </li><li>去卷积的数据保存到磁盘。 </li><li>用下面的命令使用免费提供的图像重建软件20:重建--input result_from_8_1_4.DSC --output reconstructed_image.DSC --steps 100 --size 256 </li><li>从8.1.5加载结果到光谱仪的软件以供日后参考。 </li></ol></li><li>分析记录的扩散试验<ol><li>启动数据分析软件，进入到图3中所示的软件的"装载"标签。从步骤6.3下"扩散试验"装入扩散实验。负载下的"扩散试验W / O梯度"步骤7.1.2对应的点扩散函数。从步骤7.3.2下的"谐振器简介实验"并从步骤7.3.3下的"谐振腔轮廓EXP W / O梯度"的结果，将结果。 </li><li>转到图4中所示的谐振器敏感度标签</s仲&gt;使用7.3.3点扩散函数从实验7.3.2执行数据的卷积。降低噪声功率值，直到结果是嘈杂，然后将其抬，直到噪音刚好消失。 </li><li>去，以便从7.1去卷积使用实验记录在6.2每个场扫描为点扩展函数在图5所示的一维的自旋密度分布标签。降低噪声功率值，直到结果是嘈杂，然后将其抬，直到噪音刚好消失。 </li><li>切换到如图6所示的作物面积选项卡，选中完全位于气凝胶在那里旋转探头正要从上面在该地区的第一时间步进入和内部扩散热图的区域。如果有疑问，从8.1.6加载重建图像光谱仪软件，以帮助识别气凝胶的确切位置。 </li><li>从步骤8.2在样品的向下方向增加的区域，使得没有自旋概率Ë到达的区域的实验时间内的下边界。参见图6，以供参考。 </li><li>切换到图7和压配合所示的涌入标签。左边的面板显示剪切区域从8.2.5沿位置轴的积分。 </li><li>验证中间面板所示的曲线从零开始，并立即开始上升。如果不是的话，回去8.2.5。 </li><li>验证中间面板中显示的红线后面的黑色数据点。 </li></ol></li><li>模拟一维自旋浓度随时间和合适的扩散系数<ol><li>切换到扩散系数选项卡，压配合。 </li><li>等待的计算的结果。 </li><li>验证左侧所示的实验数据显示在右边的数字数据相匹配。 </li><li>阅读翻译宏观扩散系数D 宏的值是DISPLAYED在屏幕上。 </li></ol></li></ol>

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K., Schneider, D. J., Freed, J. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Rapid+determination+of+translational+diffusion+coefficients+using+ESR+imaging.">Rapid determination of translational diffusion coefficients using ESR imaging.</a> J. Magn. Reson. 79 (3), 474-492 (1988).</li><li>Hornak, J. P., Moscicki, J. K., Schneider, D. J., Freed, J. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Diffusion+coefficients+in+anisotropic+fluids+by+ESR+imaging+of+concentration+profiles.">Diffusion coefficients in anisotropic fluids by ESR imaging of concentration profiles.</a> J. Chem. Phys. 84 (6), 3387-3395 (1986).</li><li>Berliner, L. J., Fujii, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=EPR+imaging+of+diffusional+processes+in+biologically+relevant+polymers.">EPR imaging of diffusional processes in biologically relevant polymers.</a> J. Magn. Reson. 69 (1), 68-72 (1986).</li><li>Degtyarev, Y. N., Schlick, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Diffusion+Coefficients+of+Small+Molecules+as+Guests+in+Various+Phases+of+Pluronic+L64+Measured+by+One-Dimensional+Electron+Spin+Resonance+Imaging.">Diffusion Coefficients of Small Molecules as Guests in Various Phases of Pluronic L64 Measured by One-Dimensional Electron Spin Resonance Imaging.</a> Langmuir. 15 (15), 5040-5047 (1999).</li><li>Marek, A., Labsk&#253;, J., Ko&#328;&#225;k, &. #. 2. 6. 8. ;., Pila&#345;, J., Schlick, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Translational+Diffusion+of+Paramagnetic+Tracers+in+HEMA+Gels+and+in+Concentrated+Solutions+of+PolyHEMA+by+1D+Electron+Spin+Resonance+Imaging.">Translational Diffusion of Paramagnetic Tracers in HEMA Gels and in Concentrated Solutions of PolyHEMA by 1D Electron Spin Resonance Imaging.</a> Macromolecules. 35 (14), 5517-5528 (2002).</li><li>Shin, Y. K., Ewert, U., Budil, D. E., Freed, J. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Microscopic+versus+macroscopic+diffusion+in+model+membranes+by+electron+spin+resonance+spectral-spatial+imaging.">Microscopic versus macroscopic diffusion in model membranes by electron spin resonance spectral-spatial imaging.</a> Biophys. J. 59 (4), 950-957 (1991).</li><li>Spitzbarth, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Simultaneous+Monitoring+of+Macroscopic+and+Microscopic+Diffusion+of+Guest+Molecules+in+Silica+and+Organosilica+Aerogels+by+Spatially+and+Time-Resolved+Electron+Paramagnetic+Resonance+Spectroscopy.">Simultaneous Monitoring of Macroscopic and Microscopic Diffusion of Guest Molecules in Silica and Organosilica Aerogels by Spatially and Time-Resolved Electron Paramagnetic Resonance Spectroscopy.</a> J. Phys. Chem. C. 119 (30), 17474-17479 (2015).</li><li>Kruczala, K., Schlick, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Measuring+Diffusion+Coefficients+of+Nitroxide+Radicals+in+Heterophasic+Propylene&#8722;Ethylene+Copolymers+by+Electron+Spin+Resonance+Imaging.">Measuring Diffusion Coefficients of Nitroxide Radicals in Heterophasic Propylene&#8722;Ethylene Copolymers by Electron Spin Resonance Imaging.</a> Macromolecules. 44 (2), 325-333 (2011).</li><li>Wessig, M., Drescher, M., Polarz, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Probing+Functional+Group+Specific+Surface+Interactions+in+Porous+Solids+Using+ESR+Spectroscopy+as+a+Sensitive+and+Quantitative+Tool.">Probing Functional Group Specific Surface Interactions in Porous Solids Using ESR Spectroscopy as a Sensitive and Quantitative Tool.</a> The J. Phys. Chem. C. 117 (6), 2805-2816 (2013).</li><li>Kuschel, A., Polarz, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Organosilica+Materials+with+Bridging+Phenyl+Derivatives+Incorporated+into+the+Surfaces+of+Mesoporous+Solids.">Organosilica Materials with Bridging Phenyl Derivatives Incorporated into the Surfaces of Mesoporous Solids.</a> Adv. Funct. Mater. 18 (8), 1272-1280 (2008).</li><li>Spitzbarth, M., Drescher, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Simultaneous+iterative+reconstruction+technique+software+for+spectral-spatial+EPR+imaging.">Simultaneous iterative reconstruction technique software for spectral-spatial EPR imaging.</a> J. Magn. Reson. 257, 79-88 (2015).</li><li>Stoll, S., Schweiger, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=EasySpin,+a+comprehensive+software+package+for+spectral+simulation+and+analysis+in+EPR.">EasySpin, a comprehensive software package for spectral simulation and analysis in EPR.</a> J. Magn. Reson. 178 (1), 42-55 (2006).</li></ol>

作者什么都没有透露。

该协议允许顺位分子的扩散的监控。一维成像方法已被选中，是因为它允许较高的时间分辨率相比，2D或3D成像。一维方式需要样品的恒定横截面面积，因为所获得的一维图像的强度不仅取决于浓度，而且在样品上的横截面面积。该方法还要求在样品内的自旋探头的EPR谱只在强度上而不是在形状改变。否则更耗时的谱空间成像，必须使用，这是本方案的范围之外。该方法也只限于系统，其中D 宏在于10 -12米2 /秒，7·10 -9 M如果样品中的区域的长度和超过之间的时间段观察1毫米1厘米之间2 /秒之间1小时和72小时16。 一个lthough所述UKON1-GEL和硅胶已在一个样品管被合成，在此过程中样品的合同。这造成气凝胶和样品管，其中禁止一个1d的成像方法来监视扩散的壁之间的间隙。这种并发症已通过将气凝胶热收缩管内部解决。不设有气凝胶和样品管之间的间隙的样品可以直接测量。二维成像实验作为对照实验，以检查旋探针是热收缩管的外面由于泄漏。二维图像可以与在分光计软件实现的滤波反投影算法被重建。在这个协议中，不过使用迭代算法20，即在噪声环境更加坚固的，提出了建议。 在使用EPR成像来研究扩散之前的作品10-15,17，实验的初始状态是精心准备最初配在小的区域中的一定量的自旋探头尽可能并具有完全隔离的样品。对于在此协议中描述的方法，旋探针的初始分布不是关键的，只要有最初不包含自旋探针样品的一部分。自旋探针进入该样品的所观察到的部分的量是直接从扩散数据的测量来确定。数据分析软件实现了在先前的工作16中记载的方法。而分光计软件包括所有需要执行在8.2预处理步骤的功能，这些步骤包括在所提供的数据分析软件。这使得更容易改变和比较的参数的选择。 当适应于不同样品的系统和设备，该光谱参数诸如扫描速度，调制振幅，调制frequ协议ency和微波功率需要根据光谱仪的手动调节，并且还在其上扩散观察需求梯度强度和时间周期被重新评估。在其中扩散在步骤6.3观测到的持续时间取决于维宏 。当一维浓度分布没有显著发生变化的实验可以停止。这也可以在解卷积前的原始数据看出。 有以下这个协议的步骤时，观察到的几个关键点。在这个协议崩溃使用的特定气凝胶和不可逆转地收缩时，他们干出来的，所以关键的是要始终保持在溶剂中淹没气凝胶。为什么高压锅在3.8填充有另外的溶剂和搅拌棒的原因是为了快速创建蒸汽压围绕气凝胶溶剂蒸发之前。当气凝胶干出来的，他们显著减少在Diameter和长度和新鲜样品必须有所准备。毛细管密封化合物会导致的EPR信号，如果它是在与溶剂直接接触，并扩散到谐振器。密封化合物和在步骤5.1溶剂之间的气泡产生的屏障，以防止这种情况的发生。 根据溶剂和样品的几何形状，可能难以在分光计调谐步骤来实现临界耦合。在这种情况下，旋转样本再试，或采取样品并验证气凝胶和包含溶剂的毛细管居中。 期间在步骤8.2.8数据分析，实验测定的自旋标记的涌入可以从配合偏离。如果是这样的话，信号的反褶积数据的信噪比不够，重做步骤8.2.2和8.2.3，增加噪声功率参数，以减少在空间的成本的噪声量解析度。如果信噪比是没有问题的，重做8.2.4通过8.2.8重新选择区域从其中D 宏 计算并确保该试验数据以及配合在自旋探头涌入标签的中间面板是通过原点的线， 如图7所示。

多孔材料发挥在实际应用中，如催化和层析1的主要作用。通过添加表面基团以及调整孔尺寸和表面特性，所述材料可以根据所需的应用程序2,3。多孔材料的功能关键取决于细孔内客体分子的扩散性能。在多孔材料，必须区分微观平移扩散常数D 微 ，它描述在一方面分子长度规模和宏观平移扩散常数D 宏扩散之间进行 另一方面，这是由扩散通过多个细孔，晶界，扭曲和材料的不均匀性的影响。 有几种磁共振方法可用来研究扩散，每个适合的一部分icular尺度。在毫米刻度，核磁共振（NMR）成像4和电子顺磁共振（EPR）成像（如在此协议提交）都可以使用。较小尺度成为通过使用核磁共振脉冲磁场梯度以及EPR实验5,6的访问。在纳米尺度，EPR谱可以通过观察自旋探针7,8之间海森堡交换作用的变化来使用。使用EPR成像范围从工业催化剂支持平移扩散， 例如，氧化铝9，研究各向异性取得高分子凝胶12流体10,11，药物释放系统- 14和膜模型15。 该协议使用EPR成像监测圆柱形spin探测器的宏观动扩散，多孔介质在原地的做法提出了一个。它展示了由日的主机 - 客户系统Ë氮氧spin探测器3-（2-Iodoacetamido）-2,2,5,5-四甲基-1-吡咯烷（IPSL）作为周期性中孔有机二氧化矽内客（PMO）UKON1-GEL气凝胶作为主机和乙醇作为溶剂。该协议已成功以前使用16比较维宏 作为测定用的EPR成像以D 微主机材料UKON1 -凝胶和硅胶和旅客的物种IPSL和三（8-羧基-2,2,6,6- perdeutero四甲基苯并〔1,2-D :4,5-D&#39;]双（1,3）二硫）甲基（三苯甲基），参见图1。 在基于连续波（CW）的EPR成像17的其它方法，扩散需要分光计以外的地方。与此相反，在这里提出的方法在原位方法使用。一系列的一维自旋密度分布ρ1d的快照（T，γ）是记录一段数小时。在此期间，一个快照是在其他之后拍摄并提供具有约5分钟的时间分辨率的实时扩散图案。 UKON1-GEL和硅胶已在3毫米内径的样品管被合成在文献中描述。16,18,19的UKON1 -凝胶和硅胶合成导致样品的收缩。将样品置于一个热缩管，以防止客体分子从气凝胶和样品管的壁之间移动的内部。这一附加步骤是没有必要的，可以直接在样品管进行合成而不改变它们的大小的样品。气凝胶样品崩溃时，他们干出来的，所以他们必须在溶剂中在任何时候都被淹没。所需要的热缩管的温度比在环境压力的乙醇的沸点。因此该协议描述了使用高压锅的提高沸腾的乙醇点。 该协议包括预先为EPR成像实验和用于监视IPSL自旋探头扩散分光计设置合成UKON1-GEL的样品制备。进行数据分析，在本地编写的软件提供并且描述其使用。从分光计的原始数据可以直接装载。软件计算的空间1d中的自旋密度分布ρ1D（T，γ），并考虑到谐振器灵敏度分布。用户可以选择的气凝胶和一个时间窗口，在其上扩散常数将被确定的区域。然后，该软件确定基于选择扩散方程的边界条件，解决了扩散方程。它支持最小二乘拟合找到维宏其中数值解的实验数据的最佳匹配的值。 ρ1D（T，γ）给出直接访问的浓度，并且不通过样品的横截面的变化的影响。对于维宏访问值的范围 估计16 10 7 /秒之间-12米2 /秒和·10 -9 m 2以下。

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>X-Band spectrometer</td>
			<td>Bruker</td>
			<td>E580</td>
			<td></td>
		</tr>
		<tr>
			<td>Spectrometer software</td>
			<td>Bruker</td>
			<td>Xepr 2.6b.108</td>
			<td></td>
		</tr>
		<tr>
			<td>gradient coil system</td>
			<td>Bruker</td>
			<td>E540 GCX2</td>
			<td></td>
		</tr>
		<tr>
			<td>imaging resonator</td>
			<td>Bruker</td>
			<td>TMHS 1007</td>
			<td></td>
		</tr>
		<tr>
			<td>micro-classic pipette controller</td>
			<td>Brand</td>
			<td>25900</td>
			<td></td>
		</tr>
		<tr>
			<td>microcapillary ringcaps 50 &#181;l</td>
			<td>Hirschmann</td>
			<td>9600150</td>
			<td>inner diameter 0.5 mm</td>
		</tr>
		<tr>
			<td>EPR sample tube 2 mm inner diameter</td>
			<td>Bruker</td>
			<td>ER 221TUB/2</td>
			<td></td>
		</tr>
		<tr>
			<td>EPR sample tube 4 mm inner diameter</td>
			<td>Bruker</td>
			<td>ER 221TUB/4</td>
			<td></td>
		</tr>
		<tr>
			<td>heat-shrink tubing DERAY-IB</td>
			<td>DSG-Canusa</td>
			<td>2210048952</td>
			<td>4.8 mm/2.4 mm, 2:1, 95 &#176;C - 200 &#176;C</td>
		</tr>
		<tr>
			<td>heat gun</td>
			<td>Bosch</td>
			<td>PHG 600-3</td>
			<td></td>
		</tr>
		<tr>
			<td>PTFE&#160; band</td>
			<td>VWR</td>
			<td>332362S</td>
			<td>width 12 mm</td>
		</tr>
		<tr>
			<td>test tube</td>
			<td></td>
			<td></td>
			<td>length 16 cm, diameter 1.5 cm</td>
		</tr>
		<tr>
			<td>beaker</td>
			<td></td>
			<td></td>
			<td>250 ml, height 9 cm, diameter 7 cm</td>
		</tr>
		<tr>
			<td>capillary tube sealing</td>
			<td>Fisher Scientific</td>
			<td>02-678</td>
			<td></td>
		</tr>
		<tr>
			<td>pressure cooker, 3l with trivet</td>
			<td>Beem</td>
			<td>Vital-X-Press V2, F1000675</td>
			<td></td>
		</tr>
		<tr>
			<td>magnetic stirrer with heating element</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>ethanol (p.a.)</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>ethanol (techn.)</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>syringe</td>
			<td>Hamilton</td>
			<td>1705</td>
			<td>0.05 ml, custom length: 20 cm,</td>
		</tr>
		<tr>
			<td>Pasteur capillary pipette</td>
			<td></td>
			<td></td>
			<td>length 23 cm</td>
		</tr>
		<tr>
			<td>data analysis software</td>
			<td>homemade</td>
			<td></td>
			<td>Available for download at http://www.uni-konstanz.de/drescher/software. Requires Matlab.</td>
		</tr>
		<tr>
			<td>UKON1-GEL</td>
			<td>kindly provided by Prof. Sebastian Polarz, Martin Wessig and Andreas Schachtschneider&#160;</td>
			<td></td>
			<td>See references 16, 18, 19 for the synthesis</td>
		</tr>
	</tbody>
</table>

in situ monitoring of diffusion of guest molecules in porous media using electron paramagnetic resonance imaging

A method is demonstrated to monitor macroscopic translational diffusion using electron paramagnetic resonance (EPR) imaging. A host-guest system with nitroxide spin probe 3-(2-Iodoacetamido)-2,2,5,5-tetramethyl-1-pyrrolidinyloxy (IPSL) as a guest inside the periodic mesoporous organosilica (PMO) aerogel UKON1-GEL as a host and ethanol as a solvent is used as an example to describe the protocol. Data is shown from a previous publication, where the protocol has been applied to both IPSL and Tris(8-carboxy-2,2,6,6-perdeutero-tetramethyl-benzo[1,2-d:4,5-d&#8242;]bis(1,3)dithiole) methyl (Trityl) as guest molecules and UKON1-GEL and SILICA-GEL as host systems. 
A method is shown to prepare aerogel samples that cannot be synthesized directly in the sample tube for measurement due to a size change during synthesis. The aerogel is attached to sample tubes using heat shrink tubing and a pressure cooker to reach the necessary temperature without evaporating the solvent in the process. The method does not assume a clearly defined initial distribution of guest molecules at the start of the measurement. Instead, it requires a reservoir on top of the aerogel and experimentally determines the influx rate during data analysis.
The diffusion is monitored continually over a period of 20 hr by recording the 1d spin density profile within the sample. The spectrometer settings for the imaging experiment are described quantitatively. Data analysis software is provided to take the resonator sensitivity profile into account and to numerically solve the diffusion equation. The software determines the macroscopic translational diffusion coefficient by least square minimization of the difference between the experiment and the numerical solution of the diffusion equation.

收缩管内的气凝胶的照片和示意图示于图2a和2b。在图2c的二维EPR图像清楚地显示了气凝胶的上边缘。气凝胶上述样品管内ρ1d的强度是低虽然自旋探针的浓度是在至少高达气凝胶内。然而，垂直于图象平面的样本深度是由于样品管的小内径小得多。注意，EPR图像还示出在该样品管无气泡和气凝胶似乎不具有热收缩管的收缩过程中引入的任何裂缝。 图8a示出在UKON1-GEL一个三苯甲基的扩散热图。 图8C示出了用于IPSL在UKON1 -凝胶。Figuress图8b相同的数据</stro纳克&gt;和8D分别示出了匹配选自（a）和（c）的实验数据，该扩散方程的数值解。热图的每个垂直切片显示了自旋探头在一个固定的时间点上的浓度分布。在实验开始时的自旋探头在样品的顶部浓缩。随着时间的增加，他们通过样品传播，而新的旋转探头从顶部进入。热图显示该定性三苯甲基宏观平移扩散比IPSL的宏观平移扩散显著慢。这是可以预料的，因为三苯比IPSL和孔系统更大和溶剂是相同的。 为三苯甲基和IPSL在UKON1 -凝胶和硅胶宏观平移扩散系数示于图9中 。为了比较， 图9还示出了用于IPSL在乙醇中2.1微观平移扩散系数·10 -10米2 /秒，这已经导出用软件21来确定如在先前描述的旋转相关时间从步骤7.1.2拟合谱线形状第16条。 维宏的定量分析 显示了比较IPSL较大的三苯甲基分子的扩散速度较慢。 UKON1-GEL和硅胶之间的比较显示了维宏非常相似的价值观。这是意料之中的，因为气凝胶的孔结构是类似的，自旋探针和存在于UKON1 -凝胶表面基团之间的相互作用是不足够强以显著影响ð 宏 。加入甘油至溶剂的粘度增加，并示出了用于三苯甲基的扩散系数的进一步降低。在UKON1-GEL和硅胶为三苯实验有bEEN重复来自同一批次的样品。误差棒显示维宏的标准偏差。 <img alt="图1" src="/files/ftp_upload/54335/54335fig1.jpg" /> 图 1: 自旋探头的结构式 （a）三苯自旋探头和（b）IPSL探针的结构式。从美国化学学会16许可转载。 <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/54335/54335fig1large.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/54335/54335fig2.jpg" /> 图 2: 准备样品 （ 一 ）照片，（B）示意图和（c）二维自旋密度图像注射日之后29小时在气凝胶的顶级电子自旋探头。从美国化学学会16许可转载。 <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/54335/54335fig2large.jpg" target="_blank">请点击此处查看该图的放大版本。</a> <img alt="图3" src="/files/ftp_upload/54335/54335fig3.jpg" /> 图 3: 加载数据的软件截图图中显示了用于数据分析（步骤8.2.1）软件的加载屏幕。从左至右加载以下数据:从扩散实验的原始数据（步骤6），相应的点扩散函数（步骤7.1），场扫描为填充自旋探头在磁场梯度的存在下沿样品轴线的毛细管（7.3.2）和相应的点扩散函数（步骤7.3.3）。 <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/54335/54335fig3large.jpg" target="_blank">请点击此处</a>查看该图的放大版本。 <img alt="图4" src="/files/ftp_upload/54335/54335fig4.jpg" /> 图 4: 在谐振器灵敏度分布的测定图中显示了用于数据分析（步骤8.2.2）软件的谐振器灵敏度画面。在左边，它示出了用于填充有记录在沿着样品轴线（7.3.2）的磁场梯度的存在下自旋探头毛细管现场扫描并在中间它显示了相应的点扩散函数（步骤7.3。 3）。在右侧，通过使用MATLAB函数deconvreg与指示的噪声功率参数反卷积确定显示沿样品轴的灵敏度谐振器配置文件。 <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/54335/54335fig4large.jpg" target="_blank">请点击此处查看该图的放大版本。</a> 图 5: 对样品中的一维的自旋密度的实验数据图显示用于数据分析（步骤8.2.3）软件的一维的自旋密度分布屏。在左边，它显示了从任意单位的扩散实验（步骤6）的强度。每个垂直线对应于某一时间点，并且是三苯甲基的自旋探头的谱线形状和1d的自旋密度分布的卷积，由谐振器灵敏度分布加权。梯度方向是沿着样品轴从下到上，使得在空间低点在更高的磁场，反之亦然给出信号。黄线由样品，其中该样品管接触气凝胶和自旋探针溶液的直径从样品管气凝胶的较大直径的内径跳跃的顶部创建。蓝线由已由于扩散先进最远入气凝胶的那些自旋探头形成。中间面板显示了用于解卷积的自旋探头的谱线形状。右侧面板显示的颜色由卷积使用Matlab的函数deconvreg为在每个时间点所指示的噪声功率参数确定沿随时间的样本轴编码1d的自旋灵敏度分布。磁场轴已被转换成一个空间位置轴使用磁场梯度强度，其中正值对应于样品和负值的顶部对应于样品的底部。气凝胶的顶部可以被看作是在约3.5毫米的水平线。低于该线，旋探针通过气凝胶的传播可以被看作是在垂直方向上随着时间的增加黄色区域的扩大。 <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/54335/54335fig5large.jpg" target="_blank">请</a>此处查看该图的放大版本。 <img alt="图6" src="/files/ftp_upload/54335/54335fig6.jpg" /> 图6: 裁剪所述1d中自旋密度到感兴趣的区域中的图显示了用于数据分析（步骤8.2.4）软件的作物面积步骤。它示出了从上左侧步骤8.2.3 1d的自旋密度。的数据直接从图5的右手侧面板取和被限制到谐振器灵敏度分布是其最大值的大于10％的区域。右手侧示出了相同的数据，但裁剪为用户已选择的区域。扩散系数将只从该区域被确定。 <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/54335/54335fig6large.jpg" target="_blank">请点击此处查看该图的放大版本。</a> <i毫克ALT ="图7"SRC ="/文件/ ftp_upload / 54335 / 54335fig7.jpg"/&gt; 图7: 确定自旋探针随时间的流入率该图显示用于数据分析（步骤8.2.6）软件的自旋探头涌入步骤。在左手侧的面板的每个垂直切片是相对于为每个时间点的位置的一维的自旋密度的积分函数。负值已被更改为零。中心面板显示每个点的观察区域内的自旋的量在时间上作为单独的数据点，并通过在左手侧的面板的最上面的行确定。红线是数据的指数拟合。在右手侧的面板显示在中央面板的数据的时间导数，并且对应于自旋探头随时间的涌入。以避免由实验数据的数值衍生物引入的噪声，红线已解析从前的参数来计算<html>中心面板的ponential配合和它被用作边界条件来求解扩散等式，在步骤8.2.7.1。通常不需要在左侧的面板，但可用于验证软件使用的中间数据， <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/54335/54335fig7large.jpg" target="_blank">请点击这里查看该图的放大版本。</a> <img alt="图8" src="/files/ftp_upload/54335/54335fig8.jpg" /> 图8:在一段时间1d的自旋密度实验测量ρ1D（T，Y）以任意单位在UKON1-GEL用于:（a）三苯甲基和（c）IPSL溶液和（b）中，（D扩散方程的数值解）， 分别。重印与来自美国化学学会16权限。/54335/54335fig8large.jpg"目标="_空白"&gt;点击此处查看该图的放大版本。 <img alt="图9" src="/files/ftp_upload/54335/54335fig9.jpg" /> 图 9: 获得扩散系数试验获得的宏观平移扩散系数ð 宏 。显示用各个样品从同一批多个测量值的标准偏差。 IPSL的微观平移扩散系数D 宏被表示为用于与在模拟光谱的旋转相关时间的确定的不确定性的估计进行比较的虚线，表示为虚线16。从美国化学学会16许可再版。 <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/54335/54335fig9large.jpg" target="_blank">PLE</a>ASE点击此处查看该图的放大版本。

Watch this Scientific Journal Video about In Situ Monitoring of Diffusion of Guest Molecules in Porous Media Using Electron Paramagnetic Resonance Imaging at JoVE.com

In Situ Monitoring of Diffusion of Guest Molecules in Porous Media Using Electron Paramagnetic Resonance Imaging

A protocol for the in situ monitoring of the diffusion of guest molecules in porous media using electron paramagnetic resonance (EPR) imaging is presented.

在多孔介质中使用电子顺磁共振成像客体分子扩散的原位监测

A method is demonstrated to monitor macroscopic translational diffusion using electron paramagnetic resonance (EPR) imaging. A host-guest system with ...

in-situ-monitoring-diffusion-guest-molecules-porous-media-using

Nanyang Technological University

Research

JoVE Journal

Chemistry

In Situ Monitoring of Diffusion of Guest Molecules in Porous Media Using Electron Paramagnetic Resonance Imaging

6.3K 次观看.  Universität Konstanz. A protocol for the in situ monitoring of the diffusion of guest molecules in porous media using electron paramagnetic resonance (EPR) imaging is presented.

视频: In Situ Monitoring of Diffusion of Guest Molecules in Porous Media Using Electron Paramagnetic Resonance Imaging

Exploring the Radical Nature of a Carbon Surface by Electron Paramagnetic Resonance and a Calibrated Gas Flow

While the first Electron Paramagnetic Resonance (EPR) studies regarding the effects of oxidation on the structure and stability of carbon radicals date back to the early 1980s the focus of these early papers primarily characterized the changes to the structures under extremely harsh conditions (pH or temperature)1-3. It is also known that paramagnetic molecular oxygen undergoes a Heisenberg spin exchange interaction with stable radicals that extremely broadens the EPR signal4-6. Recently, we reported interesting results where this interaction of molecular oxygen with a certain part of the existing stable radical structure can be reversibly affected simply by flowing a diamagnetic gas through the carbon samples at STP7. As flows of He, CO2, and N2 had a similar effect these interactions occur at the surface area of the macropore system.
This manuscript highlights the experimental techniques, work-up, and analysis towards affecting the existing stable radical nature in the carbon structures. It is hoped that it will help towards further development and understanding of these interactions in the community at large.

Stable radicals that are present in carbon substrates interact with paramagnetic oxygen through a Heisenberg spin exchange. This interaction can be significantly reduced under STP conditions by flowing a diamagnetic gas over the carbon system. This manuscript describes a simple method to characterize the nature of those radicals.

通过电子顺磁共振和校准气体流量探索碳表面的激进性质

While the first Electron Paramagnetic Resonance (EPR) studies regarding the effects of oxidation on the structure and stability of carbon radicals date ...

科研

化学

Sequencing of Plant Wall Heteroxylans Using Enzymic, Chemical (Methylation) and Physical (Mass Spectrometry, Nuclear Magnetic Resonance) Techniques

This protocol describes the specific techniques used for the characterization of reducing end (RE) and internal region glycosyl sequence(s) of heteroxylans. De-starched wheat endosperm cell walls were isolated as an alcohol-insoluble residue (AIR)1 and sequentially extracted with water (W-sol Fr) and 1 M KOH containing 1% NaBH4 (KOH-sol Fr) as described by Ratnayake et al. (2014)2. Two different approaches (see summary in Figure 1) are adopted. In the first, intact W-sol AXs are treated with 2AB to tag the original RE backbone chain sugar residue and then treated with an endoxylanase to generate a mixture of 2AB-labelled RE and internal region reducing oligosaccharides, respectively. In a second approach, the KOH-sol Fr is hydrolyzed with endoxylanase to first generate a mixture of oligosaccharides which are subsequently labelled with 2AB. The enzymically released ((un)tagged) oligosaccharides from both W- and KOH-sol Frs are then methylated and the detailed structural analysis of both the native and methylated oligosaccharides is performed using a combination of MALDI-TOF-MS, RP-HPLC-ESI-QTOF-MS and ESI-MSn. Endoxylanase digested KOH-sol AXs are also characterized by nuclear magnetic resonance (NMR) that also provides information on the anomeric configuration. These techniques can be applied to other classes of polysaccharides using the appropriate endo-hydrolases.

Sequencing of Plant Wall Heteroxylans Using Enzymic, Chemical Methylation and Physical Mass Spectrometry, Nuclear Magnetic Resonance Techniques

This protocol describes the specific techniques used for the structural characterization of reducing end (RE) and internal region glycosyl sequence(s) of heteroxylans by tagging the RE with 2 aminobenzamide prior to enzymatic (endoxylanase) hydrolysis and then analysis of the resultant oligosaccharides using mass spectrometry (MS) and nuclear magnetic resonance (NMR).

使用酶法，化学（甲基化）和物理（质谱，核磁共振）技术，植物墙Heteroxylans测序

This protocol describes the specific techniques used for the characterization of reducing end (RE) and internal region glycosyl sequence(s) of ...

Preparation and In Vitro Characterization of Dendrimer-based Contrast Agents for Magnetic Resonance Imaging

Paramagnetic complexes of gadolinium(III) with acyclic or macrocyclic chelates are the most commonly used contrast agents (CAs) for magnetic resonance imaging (MRI). Their purpose is to enhance the relaxation rate of water protons in tissue, thus increasing the MR image contrast and the specificity of the MRI measurements. Current clinically approved contrast agents are low molecular weight molecules that are rapidly cleared from the body. The use of dendrimers as carriers of paramagnetic chelators can play an important role in the future development of more efficient MRI contrast agents. Specifically, the increase in local concentration of the paramagnetic species results in a higher signal contrast. Furthermore, this CA provides a longer tissue retention time due to its high molecular weight and size. Here, we demonstrate a convenient procedure for the preparation of macromolecular MRI contrast agents based on poly(amidoamine) (PAMAM) dendrimers with monomacrocyclic DOTA-type chelators (DOTA &#8211; 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetate). The chelating unit was appended by exploiting the reactivity of the isothiocyanate (NCS) group towards the amine surface groups of the PAMAM dendrimer to form thiourea bridges. Dendrimeric products were purified and analyzed by means of nuclear magnetic resonance spectroscopy, mass spectrometry, and elemental analysis. Finally, high resolution MR images were recorded and the signal contrasts obtained from the prepared dendrimeric and the commercially available monomeric agents were compared.

Preparation and In Vitro Characterization of Dendrimer-based Contrast Agents for Magnetic Resonance Imaging

This protocol describes the preparation and characterization of a dendrimeric magnetic resonance imaging (MRI) contrast agent that carries cyclen-based macrocyclic chelates coordinating paramagnetic gadolinium ions. In a series of MRI experiments in vitro, this agent produced an amplified MRI signal when compared to the commercially available monomeric analogue.

制备及<em&gt;体外</em&gt;磁共振成像基于树状大分子造影剂的表征

Paramagnetic complexes of gadolinium(III) with acyclic or macrocyclic chelates are the most commonly used contrast agents (CAs) for magnetic resonance ...

In Situ Characterization of Boehmite Particles in Water Using Liquid SEM

In situ imaging and elemental analysis of boehmite (AlOOH) particles in water is realized using the System for Analysis at the Liquid Vacuum Interface (SALVI) and Scanning Electron Microscopy (SEM). This paper describes the method and key steps in integrating the vacuum compatible SAVLI to SEM and obtaining secondary electron (SE) images of particles in liquid in high vacuum. Energy dispersive x-ray spectroscopy (EDX) is used to obtain elemental analysis of particles in liquid and control samples including deionized (DI) water only and an empty channel as well. Synthesized boehmite (AlOOH) particles suspended in liquid are used as a model in the liquid SEM illustration. The results demonstrate that the particles can be imaged in the SE mode with good resolution (i.e., 400 nm). The AlOOH EDX spectrum shows significant signal from the aluminum (Al) when compared with the DI water and the empty channel control. In situ liquid SEM is a powerful technique to study particles in liquid with many exciting applications. This procedure aims to provide technical know-how in order to conduct liquid SEM imaging and EDX analysis using SALVI and to reduce potential pitfalls when using this approach.

In Situ Characterization of Boehmite Particles in Water Using Liquid SEM

We present a procedure for real-time imaging and elemental composition analysis of boehmite particles in deionized water by in situ liquid Scanning Electron Microscopy.

原位水中石粒子的液体扫描电镜表征

In situ imaging and elemental analysis of boehmite (AlOOH) particles in water is realized using the System for Analysis at the Liquid Vacuum Interface ...

Microfluidic Chips for In Situ Crystal X-ray Diffraction and In Situ Dynamic Light Scattering for Serial Crystallography

This protocol describes fabricating microfluidic devices with low X-ray background optimized for goniometer based fixed target serial crystallography. The devices are patterned from epoxy glue using soft lithography and are suitable for in situ X-ray diffraction experiments at room temperature. The sample wells are lidded on both sides with polymeric polyimide foil windows that allow diffraction data collection with low X-ray background. This fabrication method is undemanding and inexpensive. After the sourcing of a SU-8 master wafer, all fabrication can be completed outside of a cleanroom in a typical research lab environment. The chip design and fabrication protocol utilize capillary valving to microfluidically split an aqueous reaction into defined nanoliter sized droplets. This loading mechanism avoids the sample loss from channel dead-volume and can easily be performed manually without using pumps or other equipment for fluid actuation. We describe how isolated nanoliter sized drops of protein solution can be monitored in situ by dynamic light scattering to control protein crystal nucleation and growth. After suitable crystals are grown, complete X-ray diffraction datasets can be collected using goniometer based in situ fixed target serial X-ray crystallography at room temperature. The protocol provides custom scripts to process diffraction datasets using a suite of software tools to solve and refine the protein crystal structure. This approach avoids the artefacts possibly induced during cryo-preservation or manual crystal handling in conventional crystallography experiments. We present and compare three protein structures that were solved using small crystals with dimensions of approximately 10-20 &#181;m grown in chip. By crystallizing and diffracting in situ, handling and hence mechanical disturbances of fragile crystals is minimized. The protocol details how to fabricate a custom X-ray transparent microfluidic chip suitable for in situ serial crystallography. As almost every crystal can be used for diffraction data collection, these microfluidic chips are a very efficient crystal delivery method.

Microfluidic Chips for In Situ Crystal X-ray Diffraction and In Situ Dynamic Light Scattering for Serial Crystallography

This protocol describes in detail how to fabricate and operate microfluidic devices for X-ray diffraction data collection at room temperature. Additionally, it describes how to monitor protein crystallization by dynamic light scattering and how to process and analyze obtained diffraction data.

用于原位晶体 x 射线衍射和原位的微流控芯片系列晶体学的动态光散射

This protocol describes fabricating microfluidic devices with low X-ray background optimized for goniometer based fixed target serial crystallography. The ...

Using Graphene Liquid Cell Transmission Electron Microscopy to Study in Situ Nanocrystal Etching

Graphene liquid cell electron microscopy provides the ability to observe nanoscale chemical transformations and dynamics as the reactions are occurring in liquid environments. This manuscript describes the process for making graphene liquid cells through the example of graphene liquid cell transmission electron microscopy (TEM) experiments of gold nanocrystal etching. The protocol for making graphene liquid cells involves coating gold, holey-carbon TEM grids with chemical vapor deposition graphene and then using those graphene-coated grids to encapsulate liquid between two graphene surfaces. These pockets of liquid, with the nanomaterial of interest, are imaged in the electron microscope to see the dynamics of the nanoscale process, in this case the oxidative etching of gold nanorods. By controlling the electron beam dose rate, which modulates the etching species in the liquid cell, the underlying mechanisms of how atoms are removed from nanocrystals to form different facets and shapes can be better understood. Graphene liquid cell TEM has the advantages of high spatial resolution, compatibility with traditional TEM holders, and low start-up costs for research groups. Current limitations include delicate sample preparation, lack of flow capability, and reliance on electron beam-generated radiolysis products to induce reactions. With further development and control, graphene liquid cell may become a ubiquitous technique in nanomaterials and biology, and is already being used to study mechanisms governing growth, etching, and self-assembly processes of nanomaterials in liquid on the single particle level.

Using Graphene Liquid Cell Transmission Electron Microscopy to Study in Situ Nanocrystal Etching

Graphene liquid cell electron microscopy can be used to observe nanocrystal dynamics in a liquid environment with greater spatial resolution than other liquid cell electron microscopy techniques. Etching premade nanocrystals and following their shape using graphene liquid cell Transmission Electron Microscopy can yield important mechanistic information about nanoparticle transformations.

用石墨烯液细胞透射电镜研究原位纳米晶蚀刻

Graphene liquid cell electron microscopy provides the ability to observe nanoscale chemical transformations and dynamics as the reactions are occurring in ...

Photoelectron Imaging of Anions Illustrated by 310 Nm Detachment of F&#8722;

Anion photoelectron imaging is a very efficient method for the study of energy states of bound negative ions, neutral species and interactions of unbound electrons with neutral molecules/atoms. State-of-the-art in vacuo anion generation techniques allow application to a broad range of atomic, molecular, and cluster anion systems. These are separated and selected using time-of-flight mass spectrometry. Electrons are removed by linearly polarized photons (photo detachment) using table-top laser sources which provide ready access to excitation energies from the infra-red to the near ultraviolet. Detecting the photoelectrons with a velocity mapped imaging lens and position sensitive detector means that, in principle, every photoelectron reaches the detector and the detection efficiency is uniform for all kinetic energies. Photoelectron spectra extracted from the images via mathematical reconstruction using an inverse Abel transformation reveal details of the anion internal energy state distribution and the resultant neutral energy states. At low electron kinetic energy, typical resolution is sufficient to reveal energy level differences on the order of a few millielectron-volts, i.e., different vibrational levels for molecular species or spin-orbit splitting in atoms. Photoelectron angular distributions extracted from the inverse Abel transformation represent the signatures of the bound electron orbital, allowing more detailed probing of electronic structure. The spectra and angular distributions also encode details of the interactions between the outgoing electron and the residual neutral species subsequent to excitation. The technique is illustrated by the application to an atomic anion (F&#8722;), but it can also be applied to the measurement of molecular anion spectroscopy, the study of low lying anion resonances (as an alternative to scattering experiments) and femtosecond (fs) time resolved studies of the dynamic evolution of anions.

Here, we present a protocol for photoelectron imaging of anionic species. Anions generated in vacuo and separated by mass spectrometry are probed using velocity mapped photoelectron imaging, providing details of anion and neutral energy levels, anion and neutral structure and the nature of the anion electronic state.

由 F− 310 Nm 支队所示的阴离子光电子成像

Anion photoelectron imaging is a very efficient method for the study of energy states of bound negative ions, neutral species and interactions of unbound ...

Heterogeneous Removal of Water-Soluble Ruthenium Olefin Metathesis Catalyst from Aqueous Media Via Host-Guest Interaction

A highly efficient transition metal catalyst removal method is developed. The water-soluble catalyst contains a newly-designed NHC ligand for the catalyst removal via host-guest interactions. The new NHC ligand possesses an adamantyl (guest) tethered linear ethylene glycol units for hydrophobic inclusion into the cavity of a &#946;-cyclodextrin (&#946;-CD) host compound. The new NHC ligand was applied to a Ru-based olefin metathesis catalyst. The Ru catalyst demonstrated excellent activity in representative ring-closing metathesis (RCM) and ring-opening metathesis polymerization (ROMP) reactions in aqueous media as well as organic solvent, CH2Cl2. After the reaction was complete, the lingering Ru residue was removed from the aqueous solution with the efficiency of more than 99% (53 ppm of Ru residue) by simple filtration utilizing a host-guest interaction between insoluble silica-grafted &#946;-CD (host) and the adamantyl moiety (guest) on the catalyst. The new Ru catalyst also demonstrated high removal efficiency via extraction when the reaction is run in organic solvent by partitioning the crude reaction mixture between layers of diethyl ether and water. In this way, the catalyst stays in aqueous layer only. In organic layer, the residual Ru amount was only 0.14 ppm in the RCM reactions of diallyl compounds.

A removable water-soluble N-heterocyclic carbene (NHC) ligand in aqueous media via host-guest interaction has been developed. We demonstrated representative olefin metathesis reactions in water as well as in dichloromethane. Via either host-guest interaction or extraction, the residual ruthenium (Ru) catalyst was as low as 0.14 ppm after the reaction.

水介质中水溶性钌烯烃置换催化剂的异质化去除与寄主交互作用

A highly efficient transition metal catalyst removal method is developed. The water-soluble catalyst contains a newly-designed NHC ligand for the catalyst ...

Pretargeted Radioimmunotherapy Based on the Inverse Electron Demand Diels-Alder Reaction

While radioimmunotherapy (RIT) is a promising approach for the treatment of cancer, the long pharmacokinetic half-life of radiolabeled antibodies can result in high radiation doses to healthy tissues. Perhaps not surprisingly, several different strategies have been developed to circumvent this troubling limitation. One of the most promising of these approaches is pretargeted radioimmunotherapy (PRIT). PRIT is predicated on decoupling the radionuclide from the immunoglobulin, injecting them separately, and then allowing them to combine in vivo at the target tissue. This approach harnesses the exceptional tumor-targeting properties of antibodies while skirting their pharmacokinetic drawbacks, thereby lowering radiation doses to non-target tissues and facilitating the use of radionuclides with half-lives that are considered too short for use in traditional radioimmunoconjugates. Over the last five years, our laboratory and others have developed an approach to in vivo pretargeting based on the inverse electron-demand Diels-Alder (IEDDA) reaction between trans-cyclooctene (TCO) and tetrazine (Tz). This strategy has been successfully applied to pretargeted positron emission tomography (PET) and single-photon emission computed tomography (SPECT) imaging with a variety of antibody-antigen systems. In a pair of recent publications, we have demonstrated the efficacy of IEDDA-based PRIT in murine models of pancreatic ductal adenocarcinoma and colorectal carcinoma. In this protocol, we describe protocols for PRIT using a 177Lu-DOTA-labeled tetrazine radioligand ([177Lu]Lu-DOTA-PEG7-Tz) and a TCO-modified variant of the colorectal cancer targeting huA33 antibody (huA33-TCO). More specifically, we will describe the construction of huA33-TCO, the synthesis and radiolabeling of [177Lu]Lu-DOTA-PEG7-Tz, and the performance of in vivo biodistribution and longitudinal therapy studies in murine models of colorectal carcinoma.

This protocol describes the synthesis and characterization of a trans-cyclooctene (TCO)-modified antibody and a 177Lu-labeled tetrazine (Tz) radioligand for pretargeted radioimmunotherapy (PRIT). In addition, it details the use of these two constructs for in vivo biodistribution and longitudinal therapy studies in a murine model of colorectal cancer.

基于逆电子需求函数-alder 反应的隐形放射免疫治疗

While radioimmunotherapy (RIT) is a promising approach for the treatment of cancer, the long pharmacokinetic half-life of radiolabeled antibodies can ...

Preparation of Graphene-Supported Microwell Liquid Cells for In Situ Transmission Electron Microscopy

The fabrication and preparation of graphene-supported microwell liquid cells (GSMLCs) for in situ electron microscopy is presented in a stepwise protocol. The versatility of the GSMLCs is demonstrated in the context of a study about etching and growth dynamics of gold nanostructures from a HAuCl4 precursor solution. GSMLCs combine the advantages of conventional silicon- and graphene-based liquid cells by offering reproducible well depths together with facile cell manufacturing and handling of the specimen under investigation. The GSMLCs are fabricated on a single silicon substrate which drastically reduces the complexity of the manufacturing process compared to two-wafer-based liquid cell designs. Here, no bonding or alignment process steps are required. Furthermore, the enclosed liquid volume can be tailored to the respective experimental requirements by simply adjusting the thickness of a silicon nitride layer. This enables a significant reduction of window bulging in the electron microscope vacuum. Finally, a state-of-the-art quantitative evaluation of single particle tracking and dendrite formation in liquid cell experiments using only open source software is presented.

Preparation of Graphene-Supported Microwell Liquid Cells for In Situ Transmission Electron Microscopy

A protocol for preparation of graphene-supported microwell liquid cells for in situ electron microscopy of gold nanocrystals from HAuCl4 precursor solution is presented. Furthermore, an analysis routine is presented to quantify observed etching and growth dynamics.

石墨烯支持的微井液体细胞制备,用于原位透射电子显微镜

The fabrication and preparation of graphene-supported microwell liquid cells (GSMLCs) for in situ electron microscopy is presented in a stepwise protocol. ...