This work was supported by the Marie Curie International Reintegration Grant (EP7). P. D. acknowledges the support of the Israel Council for Higher Education.

1.修改提示<ol><li>购买氮化硅（ 的 Si 3 N 4）的AFM悬臂用硅提示（〜2纳米的标称悬臂半径）。 </li><li>通过在无水乙醇中浸泡20分钟，清洁每个AFM悬臂。干燥在常温下。然后通过暴露于O 2等离子体5分钟治疗悬臂。 </li><li>暂停清洁提示上述（3厘米）的含甲基三乙氧基硅烷溶液和3-（氨丙基）三乙氧基硅烷中的15:1的比例（V / V）在惰性气氛（氮气或氩气）下一个干燥器和干燥器连接到真空泵。真空2小时，以形成这两种类型的混合硅烷化合物的的单层。 </li><li>使用金属刀片保持器（用于此工艺制造）放置的尖端的热板上。然后在70℃干燥的大气条件下进行10分钟的提示。在使用前，用乙醇清洗热板，金属支架和镊子。 </li><li>很酷房T提示emperature，然后浸入尖端到在含有0.5％（体积/体积）三乙胺的氯仿5毫浓度芴-PEG-N-羟基琥珀酰亚胺的溶液中（将Fmoc-PEG-NHS，MW 5000道尔顿）1小时室内温度。 </li><li>浸在氯仿中提示5分钟，然后将它浸入二甲基甲酰胺（DMF）额外的5分钟。为了脱保护Fmoc基团所连接的PEG分子，浸在DMF中的20％哌啶（V / V）的尖端30分钟。浸在DMF尖端4分钟，然后在N-甲基-2-吡咯烷酮（NMP）为额外的4分钟。重复顺序浸渍三次。 </li><li>对的氨基酸耦合，浸入尖端到含有N-末端保护的氨基酸（AA）/二异丙基乙胺（DIPEA）/ 2-（1H-苯并三唑-1-基）-1,1,3,3-四甲基脲hexafluophosphate溶液（HBTU），以1:1的摩尔比为1:1，在30毫米的5ml NMP中1.5小时的总浓度。 </li><li>对于肽偶联，浸提示到5 mL溶液续癌宁40毫克被保护的肽的（N末端和侧链，例如将Fmoc-谷氨酰胺（TRT）-Pro - 丙氨酸 - 丝氨酸（TBU）-Ser（TBU）-Arg（PBF）-Tyr（TBU）-COOH）。 ，15毫克2-（1H苯并三唑-1-基）-1,1,3,3-四甲基脲六氟磷酸盐（HBTU），和5ml DIPEA的在NMP 2小时。 </li><li>沾NMP提示4分钟。然后，以由乙酰基保护扩孔空闲/未反应NH 2，以摩尔比4浸在乙酸酐/ DIPEA的混合物30分钟的提示:1和0.65 M在NMP中的总浓度。 </li><li> 用于肽偶联，执行两个额外的步骤。 <ol><li>为了脱保护的肽的侧链，沉浸尖端到含有95％TFA，2.5％三异丙基硅烷和2.5％水1小时的溶液中，然后用氯仿和DMF洗涤。 </li><li>为了除去Fmoc基团的肽的，沉浸尖端到在DMF中的20％哌啶（V / V）30分钟。 </li></ol></li><li>依次蘸肽/氨基酸官能化ð提示各4分钟的DMF（为肽）或NMP（氨基酸），氯仿，50％的乙醇和水。最后干燥在空气中的小费。 </li></ol> 2.表面处理<ol><li>准备云母。用透明胶带切割每次使用前基板（直径9.9毫米）。然后，用三重蒸馏水（TDW）洗涤的表面上。 </li><li>准备二氧化钛涂覆的硅。 <ol><li>切断硅晶片（100）转换成使用金刚石笔2 5cm的正方形。 </li><li>放置在一个15毫升的试管填充有丙酮衬底和超声处理它用于在超声浴五分钟。然后，将这个表面在15毫升的试管填充有异丙醇和超声处理它5分钟。用氮气干燥该衬底。 </li><li>溶解表面活性剂（ 例如 ，BYK-348）的乙醇以制备5％（重量/体积）的溶液中。然后，加入0.02毫升的表面活性剂溶液，以2 30毫升％的TiO 2分散体。 </li><li>从所得到的溶液，滴投0。2毫升干净的Si衬底上。 </li><li>退火在250℃以下滴浇铸表面，在空气中2小时。 41 </li></ol></li></ol> 3.单分子力谱测量<ol><li>用市售的双组分胶附着所需的表面到AFM的金属支架。放置金属支架中的原子力显微镜，其形状为一个小的培养皿的玻璃保持器。填用Tris缓冲液（50mM pH值= 7.4）或任何所希望的培养基此支架。然后，将保持器上的刀片保持器下方的原子力显微镜的阶段。 </li><li>校准用弹簧常数使用具有约10％的绝对不确定度的热波动方法26（包含在AFM软件）从10至30 PN /纳米AFM悬臂。 </li><li>由氨基酸或肽官能尖接近到基片测量的相互作用的力，直到其处于与一压缩基板接触〜200 PN的力，然后立即以各种速度缩回的尖端，从0.1至0.8微米/秒，对于〜200nm的距离。 </li></ol> 4.数据分析<ol><li>乘以光电二极管灵敏度（伏/米），并用实验测定的弹簧常数转换偏转值（V）来强制。 42这是通过AFM软件自动完成。 <ol><li>与一个单分子事件，记录几百曲线（800-1500）获得FD曲线。获得在单分子曲线有两个峰:第一峰值表示尖端与表面和第二个峰对应于与表面分子的特异性相互作用之间的非特异性相互作用。时，将FD曲线含有除这两个峰多，从最可能的力的计算丢弃它们。 注意:仅单个粘附事件都考虑到一个帐户（从10到曲线的30％）。 43 </li></ol></li><lI&gt;为了计算表观负荷率，适合为至少50力与与蜗杆状链（WLC）模型44的距离的曲线只是破裂之前以获得一组负荷率，然后将其用于制备的直方图的明显的负荷率。推导的肽/氨基酸和表面从现行的跳跃之间的解除绑定力从衬底分离所述悬臂之后。 </li></ol>

作者宣称，他们没有竞争的经济利益。

步骤1.3，1.4和1.7中的协议，应广泛护理和在一个非常温和的方式进行。在步骤1.3中，将尖端不应该在用硅烷混合物和硅烷化过程中应在惰性气氛（无水分）进行接触。 45这样做是为了防止多层形成和因硅烷分子容易进行水解在水分存在完成。 45 在步骤1.4中，温度和时间应妥善保管。开始步骤1.5之前，尖端应冷却到室温;否则会被损坏。在偶合步骤（1.7），所述HBTU和被检查的氨基酸或肽应完全溶解于混合物中。偶联后，洗涤用不同溶剂的尖端应该以非常温和的方式进行，以避免尖的任何损害。 所报告的技术可以申请组卷到任何肽或氨基酸。要修改的硅尖，我们使用硅烷。这是可以被改变的一般化学。例如，可以使用两个或一种类型的聚乙二醇化的硅烷的修改小费。 23，25，26如果尖端由金，然后硫醇基团可以用于尖端的修改。替代协议利用次氮（NTA）封端的接头，能够针对组氨酸，重组组氨酸标签蛋白在一起。近日，Lyubchenko 等。所述的合成和的新型聚合物接头的检查和在几个SMFS实验显示了其应用。接头的合成是基于发达磷酸酯（PA）的化学。该化学允许具有预定长度和PA组合物接头的常规合成。这些连接子的长度是均匀的，可与各种官能团来终止。此外，生物分子可以在黄金基板或提示通过天然或工程巯基与硫原子金形成共价键固定。 此方法允许在单分子水平到解除从表面的分子，而不是在本体所需要的力的定量和详细的测量。该技术的未来应用包括蛋白质与前端的附件和的新的混合材料的设计。新型复合材料和功能表面的设计和开发人员将可获得的蛋白质或肽与无机材料之间的相互作用的基本理解。这里提供了用于SMFS用原子力显微镜的协议可以作为用于研究蛋白质，肽和氨基酸的不同表面之间的相互作用的有力工具。

蛋白质和无机矿物质之间的相互作用导致具有独特性能的复合材料结构。这包括与高的机械强度或独特的光学性质的材料。 1，2例如，与矿物羟磷灰石的胶原蛋白的结合产生任一软或硬的骨骼为不同的功能。 3短肽还可以结合具有高度特异性无机材料。 4，5，6，这些肽的特异性已用于设计新的磁性和电子材料，7，8，9的制造纳米结构材料，生长晶体， 10纳米粒子合成。 11了解底层肽或蛋白质和无机材料之间的相互作用，因此使我们能够具有改进的吸附性能设计新型复合材料的机制。另外，由于植入物具有免疫应答相间是由蛋白质介导，更好地理解与无机材料的蛋白质的相互作用会提高我们的设计的植入物的能力。涉及蛋白质与无机表面相互作用的另一个重要领域是防污材料的制造。 12，13，14，15生物污染是不希望的过程，其中生物附着到表面。这对我们的生活的许多不利影响。例如，在医疗设备的细菌生物污损导致医院获得性感染。海洋生物对船和大型船舶生物污染增加<html>燃料的消耗。 12，16，17，18 单分子力谱（SMFS），使用AFM，可以直接测量的氨基酸或与基板的肽之间的相互作用。 19，20，21，22，23，24，25，26其他方法，如噬菌体展示，27，28 石英晶体微天平（QCM）29或表面等离子体共振（SPR）29，30，31，32，裁判"&gt; 33衡量肽和蛋白质来无机表面的散装的相互作用。34，35，36 这意味着，通过这些方法获得的结果涉及分子或聚集体的合奏。在SMFS，一个或非常少的分子被固定在针尖和它们与所需底物相互作用进行测量。这种方法可以扩展通过从表面拉动蛋白质研究蛋白质折叠。此外，它可以被用来测量细胞和蛋白质与抗体与其配体的结合之间的相互作用。 37，38，39，40本文详细介绍了如何可以肽或氨基酸连接到使用硅醇化学针尖。此外，本文介绍如何执行力测量，以及如何分析结果。

<table border="0" cellpadding="0" cellspacing="0" width="638">
	<colgroup>
		<col />
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	</colgroup>
	<tbody>
		<tr height="173">
			<td height="173" style="height:173px;width:164px;">Silicon nitride (Si3N4) AFM cantilevers with silicon tips</td>
			<td style="width:147px;">Bruker (Camarilo, CA, USA)</td>
			<td style="width:64px;"></td>
			<td style="width:264px;">MSNL10, nominal cantilevers radius ~2 nm&#160;</td>
		</tr>
		<tr height="106">
			<td height="106" style="height:106px;width:164px;">Methyltriethoxysilane&#160;</td>
			<td style="width:147px;">Acros Organics (New Jersey, USA)</td>
			<td style="width:64px;"></td>
			<td style="width:264px;">For Silaylation of the AFM tip&#160;</td>
		</tr>
		<tr height="106">
			<td height="106" style="height:106px;width:164px;">3-(Aminopropyl) triethoxysilane</td>
			<td style="width:147px;">Sigma-Aldrich (Jerusalem, Israel)</td>
			<td style="width:64px;"></td>
			<td style="width:264px;">Used for tip modification&#160;</td>
		</tr>
		<tr height="106">
			<td height="106" style="height:106px;width:164px;">Triisopropylsilane</td>
			<td style="width:147px;">Sigma-Aldrich (Jerusalem, Israel)</td>
			<td style="width:64px;"></td>
			<td style="width:264px;">Used for tip modification</td>
		</tr>
		<tr height="85">
			<td height="85" style="height:85px;width:164px;">N-Ethyldiisopropylamine</td>
			<td style="width:147px;">Alfa-Aesar (Lancashire, UK)</td>
			<td style="width:64px;"></td>
			<td style="width:264px;">Used for tip modification</td>
		</tr>
		<tr height="85">
			<td height="85" style="height:85px;width:164px;">Triethylamine</td>
			<td style="width:147px;">Alfa-Aesar (Lancashire, UK)</td>
			<td style="width:64px;"></td>
			<td style="width:264px;">Used for tip modification</td>
		</tr>
		<tr height="85">
			<td height="85" style="height:85px;width:164px;">Piperidine</td>
			<td style="width:147px;">Alfa-Aesar (Lancashire, UK)</td>
			<td style="width:64px;"></td>
			<td style="width:264px;">Used for tip modification</td>
		</tr>
		<tr height="232">
			<td height="232" style="height:232px;width:164px;">Fluorenylmethyloxycarbonyl-PEG-N-hydroxysuccinimide&#160; (Fmoc-PEG-NHS)</td>
			<td style="width:147px;">Iris Biotech GmbH (Deutschland, Germany)</td>
			<td style="width:64px;"></td>
			<td style="width:264px;">Used as the covalent flexible linker&#160; (MW = 5000 Da)</td>
		</tr>
		<tr height="253">
			<td height="253" style="height:253px;width:164px;">2-(1H-benzotriazol-1-yl)-1,1,3,3,-tetramethyluronium hexafluorophosphate (HBTU)</td>
			<td style="width:147px;">Alfa Aser (Heysham, England)</td>
			<td style="width:64px;"></td>
			<td style="width:264px;">Used as a coupling reagent.&#160;</td>
		</tr>
		<tr height="148">
			<td height="148" style="height:148px;width:164px;">N-methyl-2-pyrrolidone (NMP)</td>
			<td style="width:147px;">Acros Organics (New Jersey, USA)</td>
			<td style="width:64px;"></td>
			<td style="width:264px;">Used as Solvent in Tip modification procedure</td>
		</tr>
		<tr height="148">
			<td height="148" style="height:148px;width:164px;">DMF (dimethylformamide)</td>
			<td style="width:147px;">Merck (Darmstadt, Germany)</td>
			<td style="width:64px;"></td>
			<td style="width:264px;">Used as Solvent in Tip modification procedure</td>
		</tr>
		<tr height="106">
			<td height="106" style="height:106px;width:164px;">Trifluoro acetic acid (TFA)</td>
			<td style="width:147px;">Merck (Darmstadt, Germany)</td>
			<td style="width:64px;"></td>
			<td style="width:264px;"></td>
		</tr>
		<tr height="106">
			<td height="106" style="height:106px;width:164px;">Acetic anhydride</td>
			<td style="width:147px;">Merck (Darmstadt, Germany)</td>
			<td style="width:64px;"></td>
			<td style="width:264px;"></td>
		</tr>
		<tr height="106">
			<td height="106" style="height:106px;width:164px;">Peptides</td>
			<td style="width:147px;">GL Biochem (Shanghai, China).</td>
			<td style="width:64px;"></td>
			<td style="width:264px;"></td>
		</tr>
		<tr height="106">
			<td height="106" style="height:106px;width:164px;">Phenylalanine and Tyrosine&#160;</td>
			<td style="width:147px;">Biochem (Darmstadt, Germany)&#160;</td>
			<td style="width:64px;"></td>
			<td style="width:264px;"></td>
		</tr>
		<tr height="240">
			<td height="361" rowspan="7" style="height:361px;width:164px;">30% TiO2 dispersion in the mixture of solvent 2-(2-Methoxyethoxy) ethanol (DEGME) and Ethyl 3-Ethoxypropionate (EEP)</td>
			<td rowspan="7" style="width:147px;">Applied Vision Laboratories (Jerusalem, Israel)</td>
			<td rowspan="7" style="width:64px;"></td>
			<td rowspan="7" style="width:264px;">(30%) in the mixture of solvent 2-(2 Methoxyethoxy) ethanol (DEGME) and Ethyl 3-Ethoxypropionate (EEP)</td>
		</tr>
		<tr height="20">
		</tr>
		<tr height="20">
		</tr>
		<tr height="20">
		</tr>
		<tr height="20">
		</tr>
		<tr height="20">
		</tr>
		<tr height="21">
		</tr>
		<tr height="148">
			<td height="148" style="height:148px;width:164px;">Mica substrates</td>
			<td style="width:147px;">TED PELLA, INC. (Redding, California, USA)</td>
			<td style="width:64px;"></td>
			<td style="width:264px;">9.9 mm diameter</td>
		</tr>
	</tbody>
</table>

insights into the interactions of amino acids and peptides with inorganic materials using single-molecule force spectroscopy

蛋白质或肽和无机材料之间的相互作用导致了一些有趣的流程。例如，含矿物质结合蛋白导致具有独特性能的复合材料的形成。此外，生物结垢的不希望的过程是由生物分子，主要是蛋白质，表面上的吸附开始。该有机层是细菌的粘合层，并允许他们与表面相互作用。理解支配在有机 - 无机界面的相互作用的基本力因此对于研究许多领域重要，并可能导致新的材料设计用于光学，机械和生物医学应用。本文展示了单分子力光谱技术，其利用原子力显微镜测量或肽或氨基酸和良好定义的无机表面之间的粘附力。该技术包括一个协议，用于生物分子附着到AFM小费通过原子力显微镜的共价柔性接头和单分子力谱的测量。此外，这些测量值的分析是包括在内。

图1展示尖端修改程序。在第一步骤中，等离子体处理改变氮化硅尖端的表面上。尖端呈现OH基团。然后这些基团将与硅烷反应。在此步骤结束时，尖端的表面将由自由-NH 2基团所覆盖。然后，这些游离胺将用Fmoc -PEG-NHS，共价连接物反应。 Fmoc基团的PEG连接的是由pipyridine，脱保护试剂除去。最后，该检查的氨基酸或肽分子通过使用偶联试剂HBTU PEG的游离胺基耦合。 与修改后的针尖能够检查氨基酸或肽与所述表面（ 图2）的相互作用。 PEG分子从尖端肽或氨基酸分开，并允许它们自由定向。一个典型的力measu在一个力-距离曲线rement结果（ 图3）。该曲线具有从表面的前端，和一个单一的分子粘附事件的分离的一个特征点。第一峰值表示尖端与表面和第二峰之间的非特异性相互作用是指特定粘附事件。从几百FD曲线可以通过绘制粘附事件与部队的数量来构造一个直方图。这些直方图应用高斯拟合将确定最有可能的力（MPF）。 <img alt="图1" src="/files/ftp_upload/54975/54975fig1.jpg" /> 图1:提示修改程序。针尖的化学修饰的示意图。 <a href="https://ecsource-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/54975/54975fig1large.jpg" target="_blank">请点击此处查看该图的放大版本。</a> 图2:SMF的实验装置。单分子力谱设置的示意图，用于测量氨基酸或肽和所需的表面之间的相互作用。 <a href="https://ecsource-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/54975/54975fig2large.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/54975/54975fig3.jpg" /> 图3:力-距离曲线。典型的单分子的FD曲线（A）的肽谷氨酰胺-脯氨酸-丙氨酸-丝氨酸-丝氨酸-精氨酸-酪氨酸从云母表面，和（B）的氨基酸苯丙氨酸从TiO 2的表面的破裂。 <a href="https://ecsource-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/54975/54975fig3large.jpg" target="_blank">请cli来</a>这里完蛋查看此图的放大版本。 <img alt="图4" src="/files/ftp_upload/54975/54975fig4.jpg" /> 图4:直方图绘制最可能部队（MPF）和图形绘制的力比。负荷率。 （A）中的肽谷氨酰胺-脯氨酸-丙氨酸-丝氨酸-丝氨酸-精氨酸-酪氨酸的破裂力值的典型直方图从云母（以3.1±0.6 NN /秒（N = 7 8）的负载率），（B ）选自TiO 2的氨基酸苯丙氨酸（在4.2±0.7 NN /秒（装载率N = 79））。最可能的力（MPF）的值是基于高斯拟合（黑线）来计算。加载速率的依赖性的破裂力为（C）的肽谷氨酰胺-脯氨酸-丙氨酸-丝氨酸-丝氨酸-精氨酸-酪氨酸和（D）的氨基酸苯丙氨酸。动力学参数是从力的相对于表观装载r的对数的线性图外推吃了。 <a href="https://ecsource-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/54975/54975fig4large.jpg" target="_blank">请点击此处查看该图的放大版本。</a>

Watch this Scientific Journal Video about Insights into the Interactions of Amino Acids and Peptides with Inorganic Materials Using Single-Molecule Force Spectroscopy at JoVE.com

Insights into the Interactions of Amino Acids and Peptides with Inorganic Materials Using Single-Molecule Force Spectroscopy

在这里，我们提出了一个协议使用原子力显微镜（AFM）测量由单分子力光谱测量相互作用的定义明确的无机表面和任一的肽或氨基酸之间的力。从测量中获得的信息是重要的，以便更好地了解肽 - 无机材料相间。

洞察氨基酸和多肽与无机材料的使用相互作用的单分子力谱

The interactions between proteins or peptides and inorganic materials lead to several interesting processes. For example, combining proteins with minerals ...

insights-into-interactions-amino-acids-peptides-with-inorganic

Nanyang Technological University

Research

JoVE Journal

Chemistry

8.0K 次观看.  The Hebrew University of Jerusalem. 在这里，我们提出了一个协议使用原子力显微镜（AFM）测量由单分子力光谱测量相互作用的定义明确的无机表面和任一的肽或氨基酸之间的力。从测量中获得的信息是重要的，以便更好地了解肽 - 无机材料相间。 

视频: Insights into the Interactions of Amino Acids and Peptides with Inorganic Materials Using Single-Molecule Force Spectroscopy

Formation of Ordered Biomolecular Structures by the Self-assembly of Short Peptides

In nature, complex functional structures are formed by the self-assembly of biomolecules under mild conditions. Understanding the forces that control self-assembly and mimicking this process in vitro will bring about major advances in the areas of materials science and nanotechnology. Among the available biological building blocks, peptides have several advantages as they present substantial diversity, their synthesis in large scale is straightforward, and they can easily be modified with biological and chemical entities1,2. Several classes of designed peptides such as cyclic peptides, amphiphile peptides and peptide-conjugates self-assemble into ordered structures in solution. Homoaromatic dipeptides, are a class of short self-assembled peptides that contain all the molecular information needed to form ordered structures such as nanotubes, spheres and fibrils3-8. A large variety of these peptides is commercially available.
This paper presents a procedure that leads to the formation of ordered structures by the self-assembly of homoaromatic peptides. The protocol requires only commercial reagents and basic laboratory equipment. In addition, the paper describes some of the methods available for the characterization of peptide-based assemblies. These methods include electron and atomic force microscopy and Fourier-Transform Infrared Spectroscopy (FT-IR). Moreover, the manuscript demonstrates the blending of peptides (coassembly) and the formation of a &#34;beads on a string&#34;-like structure by this process.9 The protocols presented here can be adapted to other classes of peptides or biological building blocks and can potentially lead to the discovery of new peptide-based structures and to better control of their assembly.

This paper describes the formation of highly ordered peptide-based structures by the spontaneous process of self-assembly. The method utilizes commercially available peptides and common lab equipment. This technique can be applied to a large variety of peptides and may lead to the discovery of new peptide-based assemblies.

生物分子有序结构由短肽的自组装形成

In nature, complex functional structures are formed by the self-assembly of biomolecules under mild conditions. Understanding the forces that control ...

科研

化学

Preparation of Silica Nanoparticles Through Microwave-assisted Acid-catalysis

Microwave-assisted synthetic techniques were used to quickly and reproducibly produce silica nanoparticle sols using an acid catalyst with nanoparticle diameters ranging from 30-250 nm by varying the reaction conditions. Through the selection of a microwave compatible solvent, silicic acid precursor, catalyst, and microwave irradiation time, these microwave-assisted methods were capable of overcoming the previously reported shortcomings associated with synthesis of silica nanoparticles using microwave reactors. The siloxane precursor was hydrolyzed using the acid catalyst, HCl. Acetone, a low-tan &#948; solvent, mediates the condensation reactions and has minimal interaction with the electromagnetic field. Condensation reactions begin when the silicic acid precursor couples with the microwave radiation, leading to silica nanoparticle sol formation. The silica nanoparticles were characterized by dynamic light scattering data and scanning electron microscopy, which show the materials&#39; morphology and size to be dependent on the reaction conditions. Microwave-assisted reactions produce silica nanoparticles with roughened textured surfaces that are atypical for silica sols produced by St&#246;ber&#39;s methods, which have smooth surfaces.

Silica nanoparticles were prepared using acid-catalysis of a siloxane precursor and microwave-assisted synthetic techniques resulting in the controlled growth of nanomaterials ranging from 30-250 nm in diameter. The growth dynamics can be controlled by varying the initial silicic acid concentration, time of the reaction, and temperature of reaction.

Microwave-assisted synthetic techniques were used to quickly and reproducibly produce silica nanoparticle sols using an acid catalyst with nanoparticle ...

The Synthesis of [Sn10(Si(SiMe3)3)4]2- Using a Metastable Sn(I) Halide Solution Synthesized via a Co-condensation Technique

The number of well-characterized metalloid tin clusters, synthesized by applying the disproportionation of a metastable Sn(I) halide in the presence of a sterically demanding ligand, has increased in recent years. The metastable Sn(I) halide is synthesized at&#160;&#34;outer space conditions&#34; via the preparative co-condensation technique. Thereby, the subhalide is synthesized in an oven at high temperatures, around 1,300 &#176;C, and at reduced pressure by the reaction of elemental tin with hydrogen halide gas (e.g., HCl). The subhalide (e.g., SnCl) is trapped within a matrix of an inert solvent, like toluene at -196 &#176;C. Heating the solid matrix to -78 &#176;C gives a metastable solution of the subhalide. The metastable subhalide solution is highly reactive but can be stored at -78 &#176;C for several weeks. On heating the solution to room temperature, a disproportionation reaction occurs, leading to elemental tin and the corresponding dihalide. By applying bulky ligands like Si(SiMe3)3, the intermediate metalloid cluster compounds can be trapped before complete disproportionation to elemental tin. Hence, the reaction of a metastable Sn(I)Cl solution with Li-Si(SiMe3)3 gives [Sn10(Si(SiMe3)3)4]2- 1 as black crystals in high yield. 1 is formed via a complex reaction sequence including salt metathesis, disproportionation, and degradation of larger clusters. Further, 1 can be analyzed by various methods like NMR or single crystal X-ray structure analysis.

The Synthesis of [Sn10SiSiMe334]2- Using a Metastable SnI Halide Solution Synthesized via a Co-condensation Technique

The disproportionation reaction of a metastable Sn(I) chloride solution, obtained via the preparative co-condensation technique, is used for the synthesis of a metalloid tin cluster compound.

的合成[锡<sub&gt; 10</sub&gt;（SI（SIME<sub&gt; 3</sub&gt;）<sub&gt; 3</sub&gt;）<sub&gt; 4</sub&gt;]<sup&gt; 2</sup<sup&gt; -</sup&gt;使用亚稳锡（I）卤溶液通过共缩聚合成技术

The number of well-characterized metalloid tin clusters, synthesized by applying the disproportionation of a metastable Sn(I) halide in the presence of a ...

Synthesis of Cyclic Polymers and Characterization of Their Diffusive Motion in the Melt State at the Single Molecule Level

We demonstrate a method for the synthesis of cyclic polymers and a protocol for characterizing their diffusive motion in a melt state at the single molecule level. An electrostatic self-assembly and covalent fixation (ESA-CF) process is used for the synthesis of the cyclic poly(tetrahydrofuran) (poly(THF)). The diffusive motion of individual cyclic polymer chains in a melt state is visualized using single molecule fluorescence imaging by incorporating a fluorophore unit in the cyclic chains. The diffusive motion of the chains is quantitatively characterized by means of a combination of mean-squared displacement (MSD) analysis and a cumulative distribution function (CDF) analysis. The cyclic polymer exhibits multiple-mode diffusion which is distinct from its linear counterpart. The results demonstrate that the diffusional heterogeneity of polymers that is often hidden behind ensemble averaging can be revealed by the efficient synthesis of the cyclic polymers using the ESA-CF process and the quantitative analysis of the diffusive motion at the single molecule level using the MSD and CDF analyses.

A protocol for the synthesis and characterization of diffusive motion of cyclic polymers at the single molecule level is presented.

环状聚合物的合成及其在熔融状态扩散运动的表征在单分子水平

We demonstrate a method for the synthesis of cyclic polymers and a protocol for characterizing their diffusive motion in a melt state at the single ...

Electrochemical Impedance Spectroscopy as a Tool for Electrochemical Rate Constant Estimation

Electrochemical impedance spectroscopy (EIS) was used for advanced characterization of organic electroactive compounds along with cyclic voltammetry (CV). In the case of fast reversible electrochemical processes, current is predominantly affected by the rate of diffusion, which is the slowest and limiting stage. EIS is a powerful technique that allows separate analysis of stages of charge transfer that have different AC frequency response. The capability of the method was used to extract the value of charge transfer resistance, which characterizes the rate of charge exchange on the electrode-solution interface. The application of this technique is broad, from biochemistry up to organic electronics. In this work, we are presenting the method of analysis of organic compounds for optoelectronic applications.

Electrochemical impedance spectroscopy (EIS) of species that undergo reversible oxidation or reduction in solution was used for determination of rate constants of oxidation or reduction.

电化学阻抗谱作为电化学速率常数估计的一种工具

Electrochemical impedance spectroscopy (EIS) was used for advanced characterization of organic electroactive compounds along with cyclic voltammetry (CV). ...

Determination of Thermodynamic Properties of Alkaline Earth-liquid Metal Alloys Using the Electromotive Force Technique

A novel electrochemical cell based on a CaF2 solid-state electrolyte has been developed to measure the electromotive force (emf) of binary alkaline earth-liquid metal alloys as functions of both composition and temperature in order to acquire thermodynamic data. The cell consists of a chemically stable solid-state CaF2-AF2 electrolyte (where A is the alkaline-earth element such as Ca, Sr, or Ba), with binary A-B alloy (where B is the liquid metal such as Bi or Sb) working electrodes, and a pure A metal reference electrode. Emf data are collected over a temperature range of 723 K to 1,123 K in 25 K increments for multiple alloy compositions per experiment and the results are analyzed to yield activity values, phase transition temperatures, and partial molar entropies/enthalpies for each composition.

This protocol describes the measurement of the electromotive force of alkaline-earth elements in liquid metal alloys at high temperatures (723-1,123 K) to determine their thermodynamic properties, including activity, partial molar entropy, partial molar enthalpy, and phase transition temperatures, over a wide composition range.

用电动势技术测定碱土金属合金的热力学性质

A novel electrochemical cell based on a CaF2 solid-state electrolyte has been developed to measure the electromotive force (emf) of binary alkaline ...

Probing the Structure and Dynamics of Interfacial Water with Scanning Tunneling Microscopy and Spectroscopy

Water/solid interfaces are ubiquitous and play a key role in many environmental, biophysical, and technological processes. Resolving the internal structure and probing the hydrogen-bond (H-bond) dynamics of the water molecules adsorbed on solid surfaces are fundamental issues of water science, which remains a great challenge owing to the light mass and small size of hydrogen. Scanning tunneling microscopy (STM) is a promising tool for attacking these problems, thanks to its capabilities of sub-&#197;ngstr&#246;m spatial resolution, single-bond vibrational sensitivity, and atomic/molecular manipulation. The designed experimental system consists of a Cl-terminated tip and a sample fabricated by dosing water molecules in situ onto the Au(111)-supported NaCl(001) surfaces. The insulating NaCl films electronically decouple the water from the metal substrates, so the intrinsic frontier orbitals of water molecules are preserved. The Cl-tip facilitates the manipulation of the single water molecules, as well as gating the orbitals of water to the proximity of Fermi level (EF) via tip-water coupling. This paper outlines the detailed methods of submolecular resolution imaging, molecular/atomic manipulation, and single-bond vibrational spectroscopy of interfacial water. These studies open up a new route for investigating the H-bonded systems at the atomic scale.

Here, we present a protocol to investigate the structure and dynamics of interfacial water at the atomic scale, in terms of submolecular resolution imaging, molecular manipulation, and single-bond vibrational spectroscopy.

用扫描隧穿显微镜和光谱法探讨界面水的结构和动力学

Water/solid interfaces are ubiquitous and play a key role in many environmental, biophysical, and technological processes. Resolving the internal ...

Elemental-sensitive Detection of the Chemistry in Batteries through Soft X-ray Absorption Spectroscopy and Resonant Inelastic X-ray Scattering

Energy storage has become more and more a limiting factor of today's sustainable energy applications, including electric vehicles and green electric grid based on volatile solar and wind sources. The pressing demand of developing high-performance electrochemical energy storage solutions, i.e., batteries, relies on both fundamental understanding and practical developments from both the academy and industry. The formidable challenge of developing successful battery technology stems from the different requirements for different energy-storage applications. Energy density, power, stability, safety, and cost parameters all have to be balanced in batteries to meet the requirements of different applications. Therefore, multiple battery technologies based on different materials and mechanisms need to be developed and optimized. Incisive tools that could directly probe the chemical reactions in various battery materials are becoming critical to advance the field beyond its conventional trial-and-error approach. Here, we present detailed protocols for soft X-ray absorption spectroscopy (sXAS), soft X-ray emission spectroscopy (sXES), and resonant inelastic X-ray scattering (RIXS) experiments, which are inherently elemental-sensitive probes of the transition-metal 3d and anion 2p states in battery compounds. We provide the details on the experimental techniques and demonstrations revealing the key chemical states in battery materials through these soft X-ray spectroscopy techniques.

Here, we present a protocol for typical experiments of soft X-ray absorption spectroscopy (sXAS) and resonant inelastic X-ray scattering (RIXS) with applications in battery material studies.

软 x 射线吸收光谱和共振非弹性 x 射线散射法检测电池化学成分的元素敏感度

Energy storage has become more and more a limiting factor of today's sustainable energy applications, including electric vehicles and green electric grid ...

DNA Origami-Mediated Substrate Nanopatterning of Inorganic Structures for Sensing Applications

Structural DNA nanotechnology provides a viable route for building from the bottom-up using DNA as construction material. The most common DNA nanofabrication technique is called DNA origami, and it allows high-throughput synthesis of accurate and highly versatile structures with nanometer-level precision. Here, it is shown how the spatial information of DNA origami can be transferred to metallic nanostructures by combining the bottom-up DNA origami with the conventionally used top-down lithography approaches. This allows fabrication of billions of tiny nanostructures in one step onto selected substrates. The method is demonstrated using bowtie DNA origami to create metallic bowtie-shaped antenna structures on silicon nitride or sapphire substrates. The method relies on the selective growth of a silicon oxide layer on top of the origami deposition substrate, thus resulting in a patterning mask for following lithographic steps. These nanostructure-equipped surfaces can be further used as molecular sensors (e.g., surface-enhanced Raman spectroscopy (SERS)) and in various other optical applications at the visible wavelength range owing to the small feature sizes (sub-10 nm). The technique can be extended to other materials through methodological modifications; therefore, the resulting optically active surfaces may find use in development of metamaterials and metasurfaces.

Here, we describe a protocol to create discrete and accurate inorganic nanostructures on substrates using DNA origami shapes as guiding templates. The method is demonstrated by creating plasmonic gold bowtie-shaped antennas on a transparent substrate (sapphire).

脱氧核糖核酸介导基板无机结构纳米图案用于传感应用

Structural DNA nanotechnology provides a viable route for building from the bottom-up using DNA as construction material. The most common DNA ...

Covalent Attachment of Single Molecules for AFM-based Force Spectroscopy

Atomic force microscopy (AFM)-based single molecule force spectroscopy is an ideal tool for investigating the interactions between a single polymer and surfaces. For a true single molecule experiment, covalent attachment of the probe molecule is essential because only then can hundreds of force-extension traces with one and the same single molecule be obtained. Many traces are in turn necessary to prove that a single molecule alone is probed. Additionally, passivation is crucial for preventing unwanted interactions between the single probe molecule and the AFM cantilever tip as well as between the AFM cantilever tip and the underlying surface. The functionalization protocol presented here is reliable and can easily be applied to a variety of polymers. Characteristic single molecule events (i.e., stretches and plateaus) are detected in the force-extension traces. From these events, physical parameters such as stretching force, desorption force and desorption length can be obtained. This is particularly important for the precise investigation of stimuli-responsive systems at the single molecule level. As exemplary systems poly(ethylene glycol) (PEG), poly(N-isopropylacrylamide) (PNiPAM) and polystyrene (PS) are stretched and desorbed from SiOx (for PEG and PNiPAM) and from hydrophobic self-assembled monolayer surfaces (for PS) in aqueous environment.

Covalent attachment of probe molecules to atomic force microscopy (AFM) cantilever tips is an essential technique for the investigation of their physical properties. This allows us to determine the stretching force, desorption force and length of polymers via AFM-based single molecule force spectroscopy with high reproducibility.

基于AFM的力光谱单分子共价附价

Atomic force microscopy (AFM)-based single molecule force spectroscopy is an ideal tool for investigating the interactions between a single polymer and ...