这项工作是由居里夫人国际重返社会格兰特和由德国和以色列基金会的支持。我们承认雅尔Razvag先生原子力显微镜分析。

1。同芳香族二肽的自组装<ol><li>称量所需的肽在其冻干形式（ 例如 NH 2-PHE-PHE-OH，的Boc-Phe-苯丙氨酸-COOH）和通过在1,1,1,3,3,3 -六氟溶解肽制备的原液基-2 -丙醇（HFP）到适当的浓度（ 例如 100毫克/毫升为NH 2-PHE-PHE-OH和Boc-苯丙氨酸-苯丙氨酸-COOH）的7,17,46。 </li><li>采用涡和地方在板凳上，直到肽完全溶解，溶液似乎很清楚（几分钟）混合溶液中。 </li><li>稀释的肽储备溶液，用适当的溶剂中，以适当的浓度（NH 2-PHE-PHE-OH中的三次蒸馏水（TDW）对碳纳米管的形成，例如 2毫克/毫升;通过加入2微升的肽的储备溶液至98微升TDW，的Boc-Phe-苯丙氨酸-COOH的乙醇为球形结构的形成5毫克/毫升）。 </li><li>保持该溶液于室温24小时。 </li><li>为了避免任何预聚合，准备新鲜的原液每一个实验。 </li></ol> 2。两个同芳香族二肽Coassembly <ol><li>通过混合TDW和无水乙醇的等体积制备50％乙醇的溶液中。用旋涡混合两种解决方案。 </li><li>称量2毫克的NH 2-PHE-PHE-OH的肽和1毫克的Boc-Phe-苯丙氨酸-OH的肽组成。溶于HFP每种肽以100毫克/毫升的浓度。 </li><li>采用涡流混合肽原液，并将其放置在板凳上，直到肽完全溶解和解决方案似乎是清楚的。 </li><li>融合的肽储备液至所需的比例。在这个特定的实验中混合10微升的NH 2-PHE-PHE-OH的肽6微升的Boc-Phe-苯丙氨酸-OH肽（以5:3分别末期比）组成。由于HFP溶剂的高波动性，建议准备了大量的这种原液（在LEAST 10微升）。 </li><li>用旋涡混合的混合肽原液。 </li><li>稀混合的肽储备液，用50％乙醇至所需的最终浓度。在这个特定的实验中，为了分别得到的5毫克/毫升的最终浓度为NH 2-PHE-PHE-OH和3毫克/毫升的Boc-Phe-苯丙氨酸-OH添加8微升的混合肽原液到92微升的50％乙醇溶液中。用移液管轻轻摇匀瓶内的溶液。 </li><li>保持该溶液于室温放置24小时。 </li><li>应当指出的是，由于溶剂的高挥发性的性质，本实验是在肽的浓度的微小变化敏感。因此，新鲜原液应为每个实验做好准备。 </li></ol> 3。自组装结构用扫描电子显微镜（SEM）表征<ol><li>孵化后24小时，应用的肽溶液的10微升滴在玻璃科夫ř滑移和干燥在室温。 </li><li>涂层在玻璃上使用溅射涂布机90秒一薄层金（几个纳米）的样品。 </li><li>图片使用SEM工作在10〜20千伏的程序集。 </li></ol> 4。自组装结构利用透射电子显微镜（TEM）表征<ol><li>放置在200目铜网上覆盖有碳和由聚合物膜支持稳定的肽溶液的10微升下降。 </li><li> 1分钟后取出用滤纸将多余的液体。 </li><li>制备的2％乙酸双氧铀中TDW的溶液。过滤用0.22微米的过滤器单元中的溶液。 </li><li>染色的样品（阴性染色），将一滴在网格上10微升乙酸双氧铀溶液。 </li><li> 30秒后，用滤纸除去多余的液体。应当指出的是，虽然负染提高了图像的对比度，这是没有必要在所有的情况下。 </li><li>图像上个样品Ë电网通过透射电镜在120千伏运行。 </li></ol> 5。大会的原子力显微镜（AFM）三维表征<ol><li>准备样品，使用第3.1段所述的程序的原子力显微镜分析。 </li><li>使用原子力显微镜的仪器在AC模式下工作的玻璃样品进行分析。使用硅悬臂梁与3 N / m的弹簧常数和75 kHz的谐振频率。 </li><li>开始扫描大面积的网格，以便找到所需的结构。然后集中在一个特定的较小的区域，然后扫描它（扫描尺寸为2.5微米×2.5微米的图像包含在这个手稿）。 </li></ol> 6。通过FT-IR的二级结构的表征<ol><li>应用肽解决了氟化钙窗口的30微升滴。 </li><li>使该溶液干燥在RT。 </li><li>水在IR光谱中的吸附是在1650厘米-1。该峰是在肽键的酰胺I带的中心。这也是肽和蛋白质47α-螺旋结构一个典型的峰值。为了克服这个问题，避免水的信号，一个氢 - 氘交换，必须执行。放置在干燥的肽样品一滴重水（D 2 O）。下拉应足够大，以完全覆盖在窗口上的肽存款。 </li><li>让样品在真空下干燥。 </li><li>重复步骤6.3和6.4倍，以确保最大的氢 - 氘交换。保存样品在真空下，直到它的分析。 </li><li>使用氘化硫酸三甘氨酸（DTGS）检测器记录的FT-IR谱。用FT-IR系统包括一个清洗气体发生器中，为了防止湿度在试样的周围的环境。对短肽的样品，最好是扫描样品2,000×以4cm -1的分辨率。的透射率极小值可通过这样来确定与仪器ftware供给。 </li></ol>

作者宣称，他们有没有竞争的财务权益。

总之，本文说明中，基于肽的组件可以在体外形成的容易性。该过程涉及市售的肽和溶剂，并且它自发地发生的环境条件下，当加入的极性溶剂的试管中。关键的是要使用HFP作为肽的溶剂，由于肽在其他的有机溶剂的溶解度低。此外，由于HFP的高挥发性，有必要准备新鲜原液每个实验。此外，该储备液的体积应高于10微升和溶解的多肽的转移到极性溶剂（水）应迅速进行。 <p class="jove_con...

自然形成了生物分子自组装的过程有序和功能结构。了解管理这个自发过程的力量可能会导致模仿自组装体外 ，因此在材料科学10,11的区域重大进展的能力。肽，具体而言，抱很大的希望作为一个生物分子构建模块，因为他们目前大型结构的多样性，易于化学合成的，并且可以很容易地与生物和化学实体功能化。多肽自组装领域是率先由查德理和他的同事，谁表现肽纳米管的自组装由环肽交替D-和L-氨基酸12。其他成功的方法的肽组件的设计，包括线性bolaamphiphile肽5，两亲分子（AP）6，非共轭自补离子肽13，表面活性剂样肽<suP&gt; 4,14，和二嵌段copolypeptides 15。 一个更近的方法包括短芳族肽的自组装，称为同芳香族二肽。这些肽仅包含2个氨基酸，芳香性质（ 例如苯丙氨酸，苯丙氨酸，二碳酸二叔丁酯（BOC）-苯丙氨酸-Phe的生产）7,8,16-21。由这些同芳香族肽形成的结构包括管状结构，球状，片状组件和纤维6,8,15,21-32。在某些情况下，纤维产生原纤网能够产生水凝胶33-37。这些组件已被开发用于生物传感，药物输送，分子电子学等的应用程序。38-45 本文介绍了需要的，以便开始同芳香族肽的自发自组装的实验步骤。此外，它提出了肽的过程coassembly。这个过程涉及一种以上类型的肽的自组装体单体。 我们的示范包括两种市售的肽的coassembly：将二苯基丙氨酸肽（NH 2-PHE-PHE-COOH）和它的Boc保护的类似物（的Boc-Phe-苯丙氨酸-OH）。每个肽自组装成超分子结构：的二苯基丙氨酸的肽形式的管状组件和的Boc-Phe-苯丙氨酸-OH肽自组装成任一球或纤维取决于溶剂7,17,46。我们混合两种肽在一定比率和特征将得到的组合件通过电子显微镜，力显微镜和FT-IR光谱。该方法证实，它由球形元件的直径为几微米（1-4微米），它们由细长的组件的直径为几百纳米连接（〜300-800纳米）的基于肽的结构的形成。该组件像串珠串在它们的形态，如球形结构似乎就被螺纹细长的组件。因此，我们称之为这些程序集“生物分子项链”。在“生物分子项链”可以作为一种新的生物材料作为药物输送剂或作为支架用于电子应用。此外，通向肽的自组装体的方法可用于与其它类肽和生物分子。这可能会导致更好的了解参与自组装和新的有序结构形成的势力。

<table border="1">
	<tbody>
		<tr>
			<td>Name of Material/ Equipment</td>
			<td>Company</td>
			<td>Catalog Number</td>
			<td>Comments/Description</td>
		</tr>
		<tr>
			<td>NH2-Phe-Phe-OH</td>
			<td>Bachem</td>
			<td>G-2925.0001</td>
			<td></td>
		</tr>
		<tr>
			<td>Boc-Phe-Phe-OH</td>
			<td>Bachem</td>
			<td>A-3205.0005</td>
			<td></td>
		</tr>
		<tr>
			<td>1,1,1,3,3,3-hexafluoro-2-propanol</td>
			<td>Sigma-Aldrich</td>
			<td>52512-100ML</td>
			<td></td>
		</tr>
		<tr>
			<td>Ethanol absolute (Dehydrated) AR sterile</td>
			<td>Bio-Lab Ltd.</td>
			<td>52555</td>
			<td>Blending with TDW for the preparation of 50% solution</td>
		</tr>
		<tr>
			<td>Uranyl acetate</td>
			<td>Sigma-Aldrich</td>
			<td>73943</td>
			<td>For negative staining. It is possible to work without it.</td>
		</tr>
		<tr>
			<td>glass cover slip</td>
			<td>Marienfeld Laboratory Glassware</td>
			<td>110590</td>
			<td></td>
		</tr>
		<tr>
			<td>TEM grids</td>
			<td>Electron Microscopy Sciences</td>
			<td>FCF200-Cu-50</td>
			<td>Formvar/Carbon 200 Mesh, Cu</td>
		</tr>
		<tr>
			<td>Quantitive filter paper</td>
			<td>Whatman</td>
			<td>1001055</td>
			<td></td>
		</tr>
		<tr>
			<td>Deuterium Oxide (D2O)</td>
			<td>Sigma-Aldrich</td>
			<td>151882-100G</td>
			<td>99.9 atom % D</td>
		</tr>
		<tr>
			<td>CaF2 window</td>
			<td>PIKE Technologies</td>
			<td>160-1212</td>
			<td>25 mm x 2 mm window. For FT-IR measurments</td>
		</tr>
		<tr>
			<td>AFM tips</td>
			<td>NanoScience Instruments</td>
			<td>CFMR</td>
			<td>Aspire probes, CFMR-25 series</td>
		</tr>
		<tr>
			<td>Filter units</td>
			<td>Millipore</td>
			<td>SLGV033RS</td>
			<td>Millex-GV, 0.22 &#956;m, PVDF, 33 mm, gamma sterilized</td>
		</tr>
		<tr>
			<td>SEM</td>
			<td>FEI</td>
			<td></td>
			<td>Quanta 200 ESEM</td>
		</tr>
		<tr>
			<td>TEM</td>
			<td>FEI</td>
			<td></td>
			<td>Tecnai T12 G2 Spirit</td>
		</tr>
		<tr>
			<td>AFM</td>
			<td>JPK Instruments</td>
			<td></td>
			<td>A JPK NanoWizard3</td>
		</tr>
		<tr>
			<td>FT-IR</td>
			<td>Thermo Fisher Scientific</td>
			<td></td>
			<td>Nicolet 6700 advanced gold spectrometer</td>
		</tr>
		<tr>
			<td>FT-IR Purge</td>
			<td>Parker</td>
			<td></td>
			<td>BALSTON FT-IR Purge Gas Generator model 75-52</td>
		</tr>
		<tr>
			<td>OMNIC (Nicolet) software</td>
			<td>Thermo Nicolet Corporation</td>
			<td></td>
			<td>For FT-IR spectra analysis</td>
		</tr>
		<tr>
			<td>Vortex mixer</td>
			<td>Wisd Laboratory Equipment</td>
			<td></td>
			<td>ViseMix VM</td>
		</tr>
		<tr>
			<td>Weight</td>
			<td>Mettler Toledo</td>
			<td></td>
			<td>NewClassic MS</td>
		</tr>
		<tr>
			<td>Sputter coater</td>
			<td>Polaron</td>
			<td></td>
			<td>SC7640 Sputter Coater</td>
		</tr>
	</tbody>
</table>

formation of ordered biomolecular structures by the self-assembly of short peptides

在自然界中，复杂的功能性结构是由生物分子的自组装体在温和条件下形成的。了解控制自组装的力量和体外模拟这一过程将带来在材料科学和纳米技术等领域的重大进展。在现有的生物积木，肽具有若干优点，因为它们呈现大幅度的多样性，其在大规模的合成是直接的，并且它们可以很容易地与生物和化学实体1,2修改。几类设计的肽，如环肽，两亲性分子的肽和肽结合物自组装成有序结构在溶液中。同芳香族二肽，是一类含有需要形成有序结构，例如纳米管，球体和纤维3-8的所有分子信息短的自组装肽。种类繁多的这些肽是市售。 <p级=“jove_content”&gt;本文提出，导致由同芳香族肽的自组装形成有序结构的过程。该协议只需要商业试剂和基本的实验室设备。此外，本文描述了一些可用于基于肽的程序集的表征的方法。这些方法包括电子和原子力显微镜和傅里叶变换红外光谱（FT-IR）。此外，演示文稿的肽的混合（coassembly）及类似结构通过该方法是“上一个珠子串”的形成。9这里介绍的协议可以潜在地适用于其它类的肽或生物构建块的，并且可以导致新的基于肽的结构的发现和更好地控制他们的集会。

本文描述了一种形成有序结构在纳米和微米尺度由肽的自组装体的方法。为了证明这一点，我们提出简单的过程，表征了两个简单的芳香肽的coassembly（ 图1）。一个肽是NH 2-PHE-PHE-OH（二苯基丙氨酸）的肽，其能够自组装在水性溶液与纳米尺寸7中空管状结构。其他的肽是其Boc保护的类似物，的Boc-Phe-苯丙氨酸-OH。这种肽可形成纤维状结构中的乙醇17,46水溶液和球...

Watch this Scientific Journal Video about Formation of Ordered Biomolecular Structures by the Self-assembly of Short Peptides at JoVE.com

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

本文描述了通过自组装的自发过程中形成高度有序的基于肽的结构。该方法利用市售的肽和普通的实验室设备。这一技术可以应用到大量的各种肽，并可能导致新的基于肽的装配体的发现。

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 ...

formation-ordered-biomolecular-structures-self-assembly-short

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SCIENTISTS IN ACTION

12.7K 次观看.  The Hebrew University of Jerusalem. 本文描述了通过自组装的自发过程中形成高度有序的基于肽的结构。该方法利用市售的肽和普通的实验室设备。这一技术可以应用到大量的各种肽，并可能导致新的基于肽的装配体的发现。 

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

Origami Inspired Self-assembly of Patterned and Reconfigurable Particles

There are numerous techniques such as photolithography, electron-beam lithography and soft-lithography that can be used to precisely pattern two dimensional (2D) structures. These technologies are mature, offer high precision and many of them can be implemented in a high-throughput manner. We leverage the advantages of planar lithography and combine them with self-folding methods1-20 wherein physical forces derived from surface tension or residual stress, are used to curve or fold planar structures into three dimensional (3D) structures. In doing so, we make it possible to mass produce precisely patterned static and reconfigurable particles that are challenging to synthesize.
In this paper, we detail visualized experimental protocols to create patterned particles, notably, (a) permanently bonded, hollow, polyhedra that self-assemble and self-seal due to the minimization of surface energy of liquefied hinges21-23 and (b) grippers that self-fold due to residual stress powered hinges24,25. The specific protocol described can be used to create particles with overall sizes ranging from the micrometer to the centimeter length scales. Further, arbitrary patterns can be defined on the surfaces of the particles of importance in colloidal science, electronics, optics and medicine. More generally, the concept of self-assembling mechanically rigid particles with self-sealing hinges is applicable, with some process modifications, to the creation of particles at even smaller, 100 nm length scales22, 26 and with a range of materials including metals21, semiconductors9 and polymers27. With respect to residual stress powered actuation of reconfigurable grasping devices, our specific protocol utilizes chromium hinges of relevance to devices with sizes ranging from 100 &mu;m to 2.5 mm. However, more generally, the concept of such tether-free residual stress powered actuation can be used with alternate high-stress materials such as heteroepitaxially deposited semiconductor films5,7 to possibly create even smaller nanoscale grasping devices.

We describe experimental details of the synthesis of patterned and reconfigurable particles from two dimensional (2D) precursors. This methodology can be used to create particles in a variety of shapes including polyhedra and grasping devices at length scales ranging from the micro to centimeter scale.

折纸灵感的图案和可重构颗粒自组装

There are numerous techniques such as photolithography, electron-beam lithography and soft-lithography that can be used to precisely pattern two ...

科研

化学

Microwave-assisted Functionalization of Poly(ethylene glycol) and On-resin Peptides for Use in Chain Polymerizations and Hydrogel Formation

One of the main benefits to using poly(ethylene glycol) (PEG) macromers in hydrogel formation is synthetic versatility. The ability to draw from a large variety of PEG molecular weights and configurations (arm number, arm length, and branching pattern) affords researchers tight control over resulting hydrogel structures and properties, including Young&#8217;s modulus and mesh size. This video will illustrate a rapid, efficient, solvent-free, microwave-assisted method to methacrylate PEG precursors into poly(ethylene glycol) dimethacrylate (PEGDM). This synthetic method provides much-needed starting materials for applications in drug delivery and regenerative medicine. The demonstrated method is superior to traditional methacrylation methods as it is significantly faster and simpler, as well as more economical and environmentally friendly, using smaller amounts of reagents and solvents. We will also demonstrate an adaptation of this technique for on-resin methacrylamide functionalization of peptides. This on-resin method allows the N-terminus of peptides to be functionalized with methacrylamide groups prior to deprotection and cleavage from resin. This allows for selective addition of methacrylamide groups to the N-termini of the peptides while amino acids with reactive side groups (e.g.&#160;primary amine of lysine, primary alcohol of serine, secondary alcohols of threonine, and phenol of tyrosine) remain protected, preventing functionalization at multiple sites. This article will detail common analytical methods (proton Nuclear Magnetic Resonance spectroscopy (;H-NMR) and Matrix Assisted Laser Desorption Ionization Time of Flight mass spectrometry (MALDI-ToF)) to assess the efficiency of the functionalizations. Common pitfalls and suggested troubleshooting methods will be addressed, as will modifications of the technique which can be used to further tune macromer functionality and resulting hydrogel physical and chemical properties. Use of synthesized products for the formation of hydrogels for drug delivery and cell-material interaction studies will be demonstrated, with particular attention paid to modifying hydrogel composition to affect mesh size, controlling hydrogel stiffness and drug release.

Microwave-assisted Functionalization of Polyethylene glycol and On-resin Peptides for Use in Chain Polymerizations and Hydrogel Formation

This video will illustrate a rapid, efficient method to methacrylate poly(ethylene glycol), enabling chain polymerizations and hydrogel synthesis. It will demonstrate how to similarly introduce methacrylamide functionalities into peptides, detail common analytical methods to assess functionalization efficiency, provide suggestions for troubleshooting and advanced modifications, and demonstrate typical hydrogel characterization techniques.

保利的微波辅助功能化（乙二醇）和On-树脂链聚合反应，并形成水凝胶的肽使用

One of the main benefits to using poly(ethylene glycol) (PEG) macromers in hydrogel formation is synthetic versatility. The ability to draw from a large ...

Self-assembly of Complex Two-dimensional Shapes from Single-stranded DNA Tiles

Current methods in DNA nano-architecture have successfully engineered a variety of 2D and 3D structures using principles of self-assembly. In this article, we describe detailed protocols on how to fabricate sophisticated 2D shapes through the self-assembly of uniquely addressable single-stranded DNA tiles which act as molecular pixels on a molecular canvas. Each single-stranded tile (SST) is a 42-nucleotide DNA strand composed of four concatenated modular domains which bind to four neighbors during self-assembly. The molecular canvas is a rectangle structure self-assembled from SSTs. A prescribed complex 2D shape is formed by selecting the constituent molecular pixels (SSTs) from a 310-pixel molecular canvas and then subjecting the corresponding strands to one-pot annealing. Due to the modular nature of the SST approach we demonstrate the scalability, versatility and robustness of this method. Compared with alternative methods, the SST method enables a wider selection of information polymers and sequences through the use of de novo designed and synthesized short DNA strands.

DNA tiling is an effective approach to make programmable nanostructures. We describe the protocols to construct complex two-dimensional shapes by the self-assembly of single-stranded DNA tiles.

复杂的二维形状的从单链DNA的瓷砖自组装

Current methods in DNA nano-architecture have successfully engineered a variety of 2D and 3D structures using principles of self-assembly. In this ...

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

The interactions between proteins or peptides and inorganic materials lead to several interesting processes. For example, combining proteins with minerals leads to the formation of composite materials with unique properties. In addition, the undesirable process of biofouling is initiated by the adsorption of biomolecules, mainly proteins, on surfaces. This organic layer is an adhesion layer for bacteria and allows them to interact with the surface. Understanding the fundamental forces that govern the interactions at the organic-inorganic interface is therefore important for many areas of research and could lead to the design of new materials for optical, mechanical and biomedical applications. This paper demonstrates a single-molecule force spectroscopy technique that utilizes an AFM to measure the adhesion force between either peptides or amino acids and well-defined inorganic surfaces. This technique involves a protocol for attaching the biomolecule to the AFM tip through a covalent flexible linker and single-molecule force spectroscopy measurements by atomic force microscope. In addition, an analysis of these measurements is included.

Here we present a protocol to measure the force of interactions between a well-defined inorganic surface and either peptides or amino acids by single-molecule force spectroscopy measurements using an atomic force microscope (AFM). The information obtained from the measurement is important to better understand the peptide-inorganic material interphase.

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 ...

Grafting Multiwalled Carbon Nanotubes with Polystyrene to Enable Self-Assembly and Anisotropic Patchiness

We demonstrate a straightforward protocol to graft pristine multiwalled carbon nanotubes (MWCNTs) with polystyrene (PS) chains at the sidewalls through a free-radical polymerization strategy to enable the modulation of the nanotube surface properties and produce supramolecular self-assembly of the nanostructures. First, a selective hydroxylation of the pristine nanotubes through a biphasic catalytically mediated oxidation reaction creates superficially distributed reactive sites at the sidewalls. The latter reactive sites are subsequently modified with methacrylic moieties using a silylated methacrylic precursor to create polymerizable sites. Those polymerizable groups can address further polymerization of styrene to produce a hybrid nanomaterial containing PS chains grafted to the nanotube sidewalls. The polymer-graft content, amount of silylated methacrylic moieties introduced and hydroxylation modification of the nanotubes are identified and quantified by Thermogravimetric Analysis (TGA). The presence of reactive functional groups hydroxyl and silylated methacrylate are confirmed by Fourier Transform Infrared Spectroscopy (FT-IR). Polystyrene-grafted carbon nanotube solutions in tetrahydrofuran (THF) provide wall-to-wall collinearly self-assembled nanotubes when cast samples are analyzed by transmission electron microscopy (TEM). Those self-assemblies are not obtained when suitable blanks are similarly cast from analogous solutions containing non-grafted counterparts. Therefore, this method enables the modification of the nanotube anisotropic patchiness at the sidewalls which results into spontaneous auto-organization at the nanoscale.

A procedure for the synthesis of polystyrene-grafted multiwalled carbon nanotubes using successive chemical modification steps to selectively introduce the polymer chains to the sidewalls and their self-assembly via anisotropic patchiness is presented.

用聚苯乙烯接枝多壁纳米碳纳米管使自组装和各向异性斑块

We demonstrate a straightforward protocol to graft pristine multiwalled carbon nanotubes (MWCNTs) with polystyrene (PS) chains at the sidewalls through a ...

Liquid-cell Transmission Electron Microscopy for Tracking Self-assembly of Nanoparticles

Drying a nanoparticle dispersion is a versatile way to create self-assembled structures of nanoparticles, but the mechanism of this process is not fully understood. We have traced the trajectories of individual nanoparticles using liquid-cell transmission electron microscopy (TEM) to investigate the mechanism of the assembly process. Herein, we present the protocols used for liquid-cell TEM studies of the self-assembly mechanism. First, we introduce the detailed synthetic protocols used to produce uniformly sized platinum and lead selenide nanoparticles. Next, we present the microfabrication processes used to produce liquid cells with silicon nitride or silicon windows and then describe the loading and imaging procedures of the liquid-cell TEM technique. Several notes are included to provide helpful tips for the entire process, including how to manage the fragile cell windows. The individual motions of nanoparticles tracked by liquid-cell TEM revealed that changes in the solvent boundaries caused by evaporation affected the self-assembly process of nanoparticles. The solvent boundaries drove nanoparticles to primarily form amorphous aggregates, followed by flattening of the aggregates to produce a 2-dimensional (2D) self-assembled structure. These behaviors are also observed for different nanoparticle types and different liquid-cell compositions.

Here we introduce experimental protocols for the real-time observation of a self-assembly process using liquid-cell transmission electron microscopy.

用于跟踪纳米粒子自组装的液体细胞透射电子显微镜

Drying a nanoparticle dispersion is a versatile way to create self-assembled structures of nanoparticles, but the mechanism of this process is not fully ...

Fabrication of Spherical and Worm-shaped Micellar Nanocrystals by Combining Electrospray, Self-assembly, and Solvent-based Structure Control

Micellar nanocrystals (micelles with encapsulated nanocrystals) have become an emerging major class of nanobiomaterials. We describe a method of fabricating micellar nanocrystals based on combining top-down electrospray, bottom-up self-assembly, and solvent-based structure control. This method involves first using electrospray to generate uniform ultrafine liquid droplets, each of which functions as a micro-reactor in which self-assembly reaction occurs forming micellar nanocrystals, with the structures (micelle shape and nanocrystal encapsulation) controlled by the organic solvent used. This method is largely continuous and produces high quality micellar nanocrystal products with an inexpensive structure control approach. By using a water-miscible organic solvent tetrahydrofuran (THF), worm-shaped micellar nanocrystals can be produced due to solvent-induced/facilitated micelle fusion. Compared with the common spherical micellar nanocrystals, worm-shaped micellar nanocrystals can offer minimized non-specific cellular uptake, thus enhancing biological targeting. By co-encapsulating multiple nanocrystals into each micelle, multifunctional or synergistic effects can be achieved. Current limitations of this fabrication method, which will be part of the future work, primarily include imperfect encapsulation in the micellar nanocrystal product and the incompletely continuous nature of the process.

The present work describes a method to fabricate micellar nanocrystals, an emerging major class of nanobiomaterials. This method combines top-down electrospray, bottom-up self-assembly, and solvent-based structure control. The fabrication method is largely continuous, can produce high quality products, and possesses an inexpensive means of structure control.

结合电喷雾、自组装和溶剂型结构控制制备球形和蜗杆状胶束纳米晶

Micellar nanocrystals (micelles with encapsulated nanocrystals) have become an emerging major class of nanobiomaterials. We describe a method of ...

Synthesis and Characterization of 1,2-Dithiolane Modified Self-Assembling Peptides

This report focuses on the synthesis of an N-terminus 1,2-dithiolane modified self-assembling peptide and the characterization of the resulting self-assembled supramolecular structures. The synthetic route takes advantage of solid-phase peptide synthesis with the on-resin coupling of the dithiolane precursor molecule, 3-(acetylthio)-2-(acetylthiomethyl)propanoic acid, and the microwave-assisted thioacetate deprotection of the peptide N-terminus before final cleavage from the resin to yield the 1,2-dithiolane modified peptide. After the high-performance liquid chromatography (HPLC) purification of the 1,2-dithiolane peptide, derived from the nucleating core of the A&#946; peptide associated with Alzheimer&#39;s disease, the peptide is shown to self-assemble into cross-&#946; amyloid fibers. Protocols to characterize the amyloid fibers by Fourier-transform infrared spectroscopy (FT-IR), circular dichroism spectroscopy (CD) and transmission electron microscopy (TEM) are presented. The methods of N-terminal modification with a 1,2-dithiolane moiety to well-characterized self-assembling peptides can now be explored as model systems to develop post-assembly modification strategies and explore dynamic covalent chemistry on supramolecular peptide nanofiber surfaces.

A protocol for the synthesis of a 1,2-dithiolane modified peptide and the characterization of the supramolecular structures resulting from the peptide self-assembly.

12-Dithiolane 改性自组装肽的合成与表征

This report focuses on the synthesis of an N-terminus 1,2-dithiolane modified self-assembling peptide and the characterization of the resulting ...

Luminophore Formation in Various Conformations of Bovine Serum Albumin by Binding of Gold(III)

The purpose of the presented protocols is to study the process of Au(III) binding to BSA, yielding conformation change-induced red fluorescence (&#955;em = 640 nm) of BSA-Au(III) complexes. The method adjusts the pH to show that the emergence of the red fluorescence is correlated with the pH-induced equilibrium transitions of the BSA conformations. Red fluorescent BSA-Au(III) complexes can only be formed with an adjustment of pH at or above 9.7, which corresponds to the &#34;A-form&#34; conformation of BSA. The protocol to adjust the BSA to Au molar ratio and to monitor the time-course of the process of Au(III) binding is described. The minimum number of Au(III) per BSA, to produce the red fluorescence, is less than seven. We describe the protocol in steps to illustrate the presence of multiple Au(III) binding sites in BSA. First, by adding copper (Cu(II)) or nickel (Ni(II)) cations followed by Au(III), this method reveals a binding site for Au(III) that is not the red fluorophore. Second, by modifying BSA by thiol capping agents, another nonfluorophore-forming Au(III) binding site is revealed. Third, changing the BSA conformation by cleaving and capping of the disulfide bonds, the possible Au(III) binding site(s) are illustrated. The protocol described, to control the BSA conformations and Au(III) binding, can be generally applied to study the interactions of other proteins and metal cations.

Luminophore Formation in Various Conformations of Bovine Serum Albumin by Binding of GoldIII

The protocols for studying the binding of gold cations (Au(III)) to various conformations of bovine serum albumin (BSA) as well as for characterizing the conformational dependent unique BSA-Au fluorescence are presented.

结合金 (III.) 对牛血清白蛋白不同构象的 Luminophore 形成

The purpose of the presented protocols is to study the process of Au(III) binding to BSA, yielding conformation change-induced red fluorescence (&#955;em ...

Calcium Carbonate Formation in the Presence of Biopolymeric Additives

Biomineralization is the formation of minerals in the presence of organic molecules, often related with functional and/or structural roles in living organisms. It is a complex process and therefore a simple, in vitro, system is required to understand the effect of isolated molecules on the biomineralization process. In many cases, biomineralization is directed by biopolymers in the extracellular matrix. In order to evaluate the effect of isolated biopolymers on the morphology and structure of calcite in vitro, we have used the vapor diffusion method for the precipitation of calcium carbonate, scanning electron microscopy and micro Raman for the characterization, and ultraviolet-visible (UV/Vis) absorbance for measuring the quantity of a biopolymer in the crystals. In this method, we expose the isolated biopolymers, dissolved in a calcium chloride solution, to gaseous ammonia and carbon dioxide that originate from the decomposition of solid ammonium carbonate. Under the conditions where the solubility product of calcium carbonate is reached, calcium carbonate precipitates and crystals are formed. Calcium carbonate has different polymorphs that differ in their thermodynamic stability: amorphous calcium carbonate, vaterite, aragonite, and calcite. In the absence of biopolymers, under clean conditions, calcium carbonate is mostly present in the calcite form, which is the most thermodynamically stable polymorph of calcium carbonate. This method examines the effect of the biopolymeric additives on the morphology and structure of calcium carbonate crystals. Here, we demonstrate the protocol through the study of an extracellular bacterial protein, TapA, on the formation of calcium carbonate crystals. Specifically, we focus on the experimental set up, and characterization methods, such as optical and electron microscopy as well as Raman spectroscopy.

We describe a protocol for the precipitation and characterization of calcium carbonate crystals that form in the presence of biopolymers.

生物聚合物添加剂中碳酸钙的形成

Biomineralization is the formation of minerals in the presence of organic molecules, often related with functional and/or structural roles in living ...