我们感谢教授太平绅士斯帕茨（生物物理化学系，海德堡大学以及新材料和生物系统学系，马克斯普朗克研究所的智能系统，斯图加特）对他的鼎力支持。从马克斯 - 普朗克协会与德意志研究联合会（DFG SFB/TR79到EAC-A）的财政支持也大大承认。

1。 11-Mercaptoundecanoyl-N-琥珀酰亚胺酯（MU-NHS）的合成<ol><li>逐滴加入500毫克N-羟基琥珀酰亚胺的溶液和30mg 4 - （二甲氨基）吡啶在10ml丙酮（PA）的1克11-巯基十一酸的40ml二氯甲烷（PA）在室温（RT）。 </li><li>将反应冷却至0℃，并逐滴加入1.1克N，N&#39; -二环己基碳在10毫升二氯甲烷中（氮气氛下）。保持在低温下进行1小时反应，然后在室温搅拌过夜。 </li><li>过滤出沉淀，干燥，减压。通过快速色谱纯化，用石油苯和乙酸乙酯（PA）以1:1的比率提纯产物。 </li></ol> 2。齐金层的制备<ol><li>干净的玻璃盖玻片精确湿巾含有乙酸乙酯（PA）和甲醇（PA）1:1混合物的溶液超声仪处理他们5分钟。 RINSË基板用甲醇和在氮气流中干枯脱落。 </li><li>将干净的基板中的溅射涂覆装置。疏散室。通过溅射60秒从铬靶中取出最上面的氧化铬层。将样品在金属梁和涂层它们与10纳米的铬层，接着用40nm金层覆盖的下面。 </li></ol> 3。 BMP-2的表面固定<ol><li>溶解的MU-NHS在N，N-dimethlyformamide酰胺（DMF），以约1mM的终浓度和孵育金衬底中的MU-NHS的溶液在室温氮气气氛下4小时。 </li><li>在DMF中的声处理的表面，持续2分钟，冲洗，用DMF和MeOH，并在氮气流干燥关闭。 </li><li>制备的rhBMP-2的储备溶液在无菌4mM的盐酸与100微克/毫升（店铺等份在-80℃下）的浓度。对于工作稀释液（3.5微克/毫升），稀原液在PBS /氯化钠（PBS含有1M NaCl的）和一个djust至pH 8.5在使用前立即。 </li><li>孵育功能化MU-NHS在4℃的的rhBMP-2工作液过夜表面。除去培养上清。在PBS / NaCl中2分钟声处理的表面和洗3次，用无菌PBS / NaCl洗涤。 </li></ol> 4。表面表征<ol><li>以阻止抗体的非特异性吸附，孵育用5％BSA的表面（重量/体积）中1小时，在室温下，接着温育用抗BMP-2抗体（1:100，以1％（w / v的PBS溶液）BSA / PBS溶液）处理1小时，在室温。用PBS超声，持续30秒洗两次面。 </li><li>孵育底物与HRP偶联的二抗（1:1,000以1％（重量/体积）BSA / PBS溶液）30分钟，在RT，然后用PBS洗两次。 </li><li>使用Ampliflu红测定法测量的HRP酶的活性在570nm处用酶标仪。 </li></ol> 5。生物活性分析<ol><li>种子1×10 5个鼠C2C12每孔在6孔PL成肌细胞阿泰在生长培养基中，由含有丙酮酸补充有10％FBS，1％青霉素/链霉素和37℃/ 5％CO 2孵育在他们24小时的高葡萄糖DMEM中。 </li><li>饥饿的细胞在无血清的DMEM培养前3-5小时至播种到装饰有固定的BMP-2的表面上。 </li><li>对于短期的信号感应的调查，以200μl的新鲜的无血清DMEM替换培养基，然后将固定化的BMP-2的表面上的细胞。表面应该用细尖镊子处理，以避免刮伤。 </li><li>轻轻地取出面和吸出培养基用移液管，用PBS洗细胞两次。进到细胞反应的分析。 </li><li>对于长期的生物活性，板单元的分析到六天表面并对其进行培养，在37℃/ 5％CO 2在低血清条件下（2％FBS）中。 </li></ol>

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作者什么都没有透露。

在这个协议中，我们描述了功能化与生物活性的rhBMP-2表面的准备。该方法包括两个步骤:在金表面的双官能连接体的自组装单层（SAM）的1）初步形成，2）共价的rhBMP-2蛋白的固定化。在以前的工作中，我们验证了双官能连接子和生长因子的有效结合，并表明表面固定化的rhBMP-2保持其生物活性19。在固定化的形式呈现的生长因子的生物活性也已显示在其他研究中，表明该蛋白的释放以及随后...

骨形态发生蛋白-2（BMP-2）是转化生长因子（TGF-β）家族，并作为新生骨形成的诱导剂，以及几种组织的胚胎发育和成年人中调节动态平衡1-3的成员。 具有生物活性的同型二聚体的BMP-2蛋白的每个单体包含一个"半胱氨酸结"的主题，它是高度保守的所有骨形成蛋白4。六七个半胱氨酸残基形成稳定的每个单体分子内二硫键，而第七个半胱氨酸参与二聚化，形成了两种单体5,6之间的分子键。这个高度保守的半胱氨酸结定义了BMP-2蛋白的三维结构，并确定其独特的性能，如对热，变性剂和酸性pH 7-9的阻力。 BMP-2的结合的丝氨酸/苏氨酸激酶的跨膜受体，从而诱导信号转导<sup&gt; 10-12。取决于受体寡聚化的模式下，不同的信号通路被激活:一个Smad蛋白非依赖性信号传导级联通过p38信号导致的碱性磷酸酶诱导，而Smad蛋白依赖性途径通过受体磷酸化的结果中的Smad复合物的核转位和活化的转录活化具体靶基因，例如分化的抑制剂（ID）12-14。 在骨，BMP-2诱导间充质干细胞分化为成骨细胞，从而刺激愈合和从头形成骨。目前，重组表达的BMP-2是临床应用，以提高骨折部位的愈合。在骨组织工程常见的策略是利用注射生长因子，相比本地投递系统，是创伤小。然而， 在体内研究和临床应用表明，短的生物半衰期，非特异性禄alization和BMP-2的快速局部间隙可能导致一些地方，异位和系统性问题15。因此，为了获得有效的演示，BMP-2的范围内或之上的材料的包封或固定是必要的，它的本地和持续递送于靶位点。持续释放可以通过非共价的保留的方法，如物理截留，吸附或离子络合16来实现。然而，它是已知的蛋白质的非特异性吸附到表面可导致分子17的变性。为共价的生长因子结合，已经开发了不同类型的支撑件，在过去十年。使用双官能连接基的分子靶向的蛋白质的氨基或羧基基团例如，是一种类型的，这并不一定需要的蛋白质修饰，以实现其固定的方法。事实上，当蛋白质修饰提供调控蛋白定向的优势，引入人工结构域，肽标记和特定于站点的链可改变生长的生物活性因子17。因此，为了规避变性由于与支撑材料的相互作用，表面可以事先官能化，例如，有自组装单分子层的连接分子（SAM），接着是所需的因子18的耦合。我们已经使用了基于SAM的方法，共价固定化的BMP-2在表面上通过靶向其游离胺残基且已经表明，固定化的蛋白保留其短期和长期的生物活性19。这个协议提供了一种简单而有效的方式提供的BMP-2的细胞的体外研究在其上发生在细胞膜和调节负责信令成骨细胞内信号传导的机制。

<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>N-hydroxysuccinimide</td>
			<td>Sigma-Aldrich</td>
			<td>130672</td>
			<td></td>
		</tr>
		<tr>
			<td>4-(dimethylamino)pyridin</td>
			<td>Sigma-Aldrich</td>
			<td>522805</td>
			<td></td>
		</tr>
		<tr>
			<td>Acetone</td>
			<td>AppliChem</td>
			<td>A2282</td>
			<td></td>
		</tr>
		<tr>
			<td>11-mercaptoundecanoic acid</td>
			<td>Sigma-Aldrich</td>
			<td>674427</td>
			<td></td>
		</tr>
		<tr>
			<td>Dichlormethane</td>
			<td>Merck</td>
			<td>106050</td>
			<td></td>
		</tr>
		<tr>
			<td>N,N&#39;-dicyclohexylcarbodiimide</td>
			<td>Sigma-Aldrich</td>
			<td>D80002</td>
			<td></td>
		</tr>
		<tr>
			<td>Petroleum benzene</td>
			<td>Merck</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Glass coverslips</td>
			<td>Carl Roth</td>
			<td>M 875</td>
			<td></td>
		</tr>
		<tr>
			<td>Ethylacetate</td>
			<td>AppliChem</td>
			<td>A3550</td>
			<td></td>
		</tr>
		<tr>
			<td>Methanol</td>
			<td>Carl Roth</td>
			<td>4627</td>
			<td></td>
		</tr>
		<tr>
			<td>N,N-dimethylformamide</td>
			<td>Carl Roth</td>
			<td>T921</td>
			<td></td>
		</tr>
		<tr>
			<td>rhBMP-2</td>
			<td>R&#38;D Systems</td>
			<td>355-BM</td>
			<td>Carrier-free; expressed in E.coli</td>
		</tr>
		<tr>
			<td>PBS</td>
			<td>PAA</td>
			<td>H15-002</td>
			<td></td>
		</tr>
		<tr>
			<td>NaCl</td>
			<td>Carl Roth</td>
			<td>HN00.2</td>
			<td></td>
		</tr>
		<tr>
			<td>Poly(dimethyl siloxane) (PDMS)</td>
			<td>Dow Corning</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Sylgard 184 silicone elastomer kit</td>
			<td>Dow Corning</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Anti-rhBMP-2</td>
			<td>Sigma</td>
			<td>B9553</td>
			<td></td>
		</tr>
		<tr>
			<td>Goat anti-mouse IgG-HRP</td>
			<td>Santa Cruz</td>
			<td>sc-2005</td>
			<td>Secondary antibody</td>
		</tr>
		<tr>
			<td>Ampliflu Red assay</td>
			<td>Sigma</td>
			<td>90101</td>
			<td></td>
		</tr>
		<tr>
			<td>Dulbecco&#39;s Modified Eagle Medium (DMEM) (1x), liquid</td>
			<td>Gibco</td>
			<td>41966</td>
			<td>High glucose</td>
		</tr>
		<tr>
			<td>Fetal Bovine Serum (FBS)</td>
			<td>Sigma</td>
			<td>F7524</td>
			<td>Sterile filtered, cell culture tested</td>
		</tr>
		<tr>
			<td>Pen/Strep</td>
			<td>Gibco</td>
			<td>15140</td>
			<td></td>
		</tr>
		<tr>
			<td>Trypsin 0.05% (1x) with EDTA 4Na</td>
			<td>Gibco</td>
			<td>25300</td>
			<td></td>
		</tr>
		<tr>
			<td>Glycine (0.1 M)</td>
			<td>Riedel-de Ha&#235;n</td>
			<td>33226</td>
			<td></td>
		</tr>
		<tr>
			<td>IGEPAL CA-630 (1%)</td>
			<td>Sigma</td>
			<td>I8896</td>
			<td>Lysis buffer (ALP assay)19</td>
		</tr>
		<tr>
			<td>Magnesium chloride (MgCl2)(1 mM)</td>
			<td>Carl Roth</td>
			<td>HNO3.2</td>
			<td></td>
		</tr>
		<tr>
			<td>Zinc chloride (ZnCl2) (1 mM)</td>
			<td>Carl Roth</td>
			<td>3533.1</td>
			<td></td>
		</tr>
		<tr>
			<td>p-nitrophenylphosphate (pNPP)</td>
			<td>Sigma</td>
			<td>S0942</td>
			<td>Phosphatase substrate</td>
		</tr>
		<tr>
			<td>Anti-mysin heavy chain (MHC)</td>
			<td>Developmental Studies Hybridoma Bank, University of Iowa</td>
			<td>MF20</td>
			<td>Monoclonal antibody</td>
		</tr>
		<tr>
			<td>Alexa Fluor 488 Goat anti-mouse IgG</td>
			<td>Invitrogen</td>
			<td>A11001</td>
			<td></td>
		</tr>
		<tr>
			<td>DAPI</td>
			<td>Sigma</td>
			<td>D9542</td>
			<td></td>
		</tr>
		<tr>
			<td></td>
			<td></td>
			<td></td>
			<td>Equipment</td>
		</tr>
		<tr>
			<td>Ultrsonic bath (Sonorex Super RK 102H), Frequency 35 kHz</td>
			<td>BANDELIN electronic GmbH &#38; Co. KG</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>MED 020 Sputtercoating system</td>
			<td>BAL-TEC AG</td>
			<td></td>
			<td>Coating conditions 
			Cr: 120 mA, 1.3 x 10-2 mbar, 30 sec 
			Au: 60 mA, 5.0 x 10-2 mbar, 45 sec</td>
		</tr>
		<tr>
			<td>Tecan Infinite M200 Plate reader</td>
			<td>Tecan</td>
			<td></td>
			<td></td>
		</tr>
	</tbody>
</table>

covalent binding of bmp-2 on surfaces using a self-assembled monolayer approach

骨形态发生蛋白-2（BMP-2）是嵌入在骨组织中的细胞外基质的生长因子。 BMP-2作为间充质细胞分化为成骨细胞的触发器，从而刺激愈合和新生骨形成。与支架结合临床使用的重组人BMP-2（的rhBMP-2）提出了一些争议，根据演示文稿的方式和交付量。这里介绍的协议提供了一种简单而有效的方式提供的BMP-2的体外研究细胞。我们描述了如何形成自组装单分子层组成的异双功能连接物，并显示在下面的结合步骤中获得的rhBMP-2的共价固定。用这种方法，可以实现BMP-2的持续文稿，同时保持了蛋白质的生物活性。事实上，BMP-2的表面固定允许有针对性的调查，防止非特异性的广告orption，同时减少的生长因子的量和，最值得注意的是，阻碍了从表面不受控制的释放。由BMP-2引起的短期和长期的信号传导事件正在发生时，细胞暴露于表面呈共价固定的rhBMP-2，使得该方法适于在体外研究细胞对BMP-2刺激。

在我们的设置中，黄金被选为赋形剂，因为它提供了一种生物，但非特异性化学可调系统。另外，自组装单分子膜的应用嗣继承很多益处:通过自组装膜对金属和形式的单层缺陷少其"头部基团"自发地吸附，而其末端官能基团可以被进一步修饰。因此，他们提供一个平台，在受控而高度适应性的方式20定制界面的属性。 对于BMP-2对金涂覆的表面上的固定化，我们使用了?...

Watch this Scientific Journal Video about Covalent Binding of BMP-2 on Surfaces Using a Self-assembled Monolayer Approach at JoVE.com

Covalent Binding of BMP-2 on Surfaces Using a Self-assembled Monolayer Approach

我们描述了用于实现BMP-2的有效固定化在表面上的方法。我们的方法是基于一个自组装单层实现共价通过其游离胺残基的BMP-2的结合的形成。这个方法是研究信令在细胞膜的有用工具。

BMP-2的共价结合利用表面上的自组装单层膜法

Bone morphogenetic protein 2 (BMP-2) is a growth factor embedded in the extracellular matrix of bone tissue. BMP-2 acts as trigger of mesenchymal cell ...

covalent-binding-bmp-2-on-surfaces-using-self-assembled-monolayer

Research

Education

JoVE Journal

JoVE Core

Organic Chemistry

Chemistry

Unit 1

Covalent Bonding and Structure

SCIENTISTS IN ACTION

13.9K 次观看.  University of Heidelberg. 我们描述了用于实现BMP-2的有效固定化在表面上的方法。我们的方法是基于一个自组装单层实现共价通过其游离胺残基的BMP-2的结合的形成。这个方法是研究信令在细胞膜的有用工具。 

视频: Covalent Binding of BMP-2 on Surfaces Using a Self-assembled Monolayer Approach

Investigating Single Molecule Adhesion by Atomic Force Spectroscopy

Atomic force spectroscopy is an ideal tool to study molecules at surfaces and interfaces. An experimental protocol to couple a large variety of single molecules covalently onto an AFM tip is presented. At the same time the AFM tip is passivated to prevent unspecific interactions between the tip and the substrate, which is a prerequisite to study single molecules attached to the AFM tip. Analyses to determine the adhesion force, the adhesion length, and the free energy of these molecules on solid surfaces and bio-interfaces are shortly presented and external references for further reading are provided. Example molecules are the poly(amino acid) polytyrosine, the graft polymer PI-g-PS and the phospholipid POPE (1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoethanolamine). These molecules are desorbed from different surfaces like CH3-SAMs, hydrogen terminated diamond and supported lipid bilayers under various solvent conditions. Finally, the advantages of force spectroscopic single molecule experiments are discussed including means to decide if truly a single molecule has been studied in the experiment.

A protocol to couple a large variety of single molecules covalently onto an AFM tip is presented. Procedures and examples to determine the adhesion force and free energy of these molecules on solid supports and bio-interfaces are provided.

调查单分子粘附的原子力谱

Atomic force spectroscopy is an ideal tool to study molecules at surfaces and interfaces. An experimental protocol to couple a large variety of single ...

科研

工程学

Covalent Immobilization of Proteins for the Single Molecule Force Spectroscopy

In recent years, atomic force microscopy (AFM) based single molecule force spectroscopy (SMFS) extended our understanding of molecular properties and functions. It gave us the opportunity to explore a multiplicity of biophysical mechanisms, e.g., how bacterial adhesins bind to host surface receptors in more detail. Among other factors, the success of SMFS experiments depends on the functional and native immobilization of the biomolecules of interest on solid surfaces and AFM tips. Here, we describe a straightforward protocol for the covalent coupling of proteins to silicon surfaces using silane-PEG-carboxyls and the well-established N-hydroxysuccinimid/1-ethyl-3-(3-dimethyl-aminopropyl)carbodiimid (EDC/NHS) chemistry in order to explore the interaction of pilus-1 adhesin RrgA from the Gram-positive bacterium Streptococcus pneumoniae (S. pneumoniae) with the extracellular matrix protein fibronectin (Fn). Our results show that the surface functionalization leads to a homogenous distribution of Fn on the glass surface and to an appropriate concentration of RrgA on the AFM cantilever tip, apparent by the target value of up to 20% of interaction events during SMFS measurements and revealed that RrgA binds to Fn with a mean force of 52 pN. The protocol can be adjusted to couple via site specific free thiol groups. This results in a predefined protein or molecule orientation and is suitable for other biophysical applications besides the SMFS.

This protocol describes the covalent immobilization of proteins with a heterobifunctional silane coupling agent to silicon-oxide surfaces designed for the atomic force microscopy based single molecule force spectroscopy which is exemplified by the interaction of RrgA (pilus-1 tip adhesin of S. pneumoniae) with fibronectin.

单分子力谱中蛋白质共价固定化的研究

In recent years, atomic force microscopy (AFM) based single molecule force spectroscopy (SMFS) extended our understanding of molecular properties and ...

生物化学

Antifouling Self-assembled Monolayers on Microelectrodes for Patterning Biomolecules

We present a procedure for forming a poly(ethylene glycol) (PEG) trimethoxysilane self-assembled monolayer (SAM) on a silicon substrate with gold microelectrodes. The PEG-SAM is formed in a single assembly step and prevents biofouling on silicon and gold surfaces. The SAM is used to coat microelectrodes patterned with standard, positive-tone lithography. Using the microtubule as an example, we apply a DC voltage to induce electrophoretic migration to the SAM-coated electrode in a reversible manner. A flow chamber is used for imaging the electrophoretic migration and microtubule patterning in situ using epifluorescence microscopy. This method is generally applicable to biomolecule patterning, as it employs electrophoresis to immobilize target molecules and thus does not require specific molecular interactions. Further, it avoids problems encountered when attempting to pattern the SAM molecules directly using lithographic techniques. The compatibility with electron beam lithography allows this method to be used to pattern biomolecules at the nanoscale.

We present a procedure for forming a poly(ethylene glycol) self-assembled monolayer (PEG-SAM) on a silicon substrate with gold microelectrodes. The PEG-SAM is formed in a single step and prevents biofouling on silicon and gold surfaces. Electrophoresis is then used for patterning biomolecules down to the nanoscale.

防污图案生物分子自组装膜的微电极为

We present a procedure for forming a poly(ethylene glycol) (PEG) trimethoxysilane self-assembled monolayer (SAM) on a silicon substrate with gold ...

生物学

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 ...

化学

Biomimetic Materials to Characterize Bacteria-host Interactions

Bacterial attachment to host cells is one of the earliest events during bacterial colonization of host tissues and thus a key step during infection. The biochemical and functional characterization of adhesins mediating these initial bacteria-host interactions is often compromised by the presence of other bacterial factors, such as cell wall components or secreted molecules, which interfere with the analysis. This protocol describes the production and use of biomimetic materials, consisting of pure recombinant adhesins chemically coupled to commercially available, functionalized polystyrene beads, which have been used successfully to dissect the biochemical and functional interactions between individual bacterial adhesins and host cell receptors. Protocols for different coupling chemistries, allowing directional immobilization of recombinant adhesins on polymer scaffolds, and for assessment of the coupling efficiency of the resulting &#8220;bacteriomimetic&#8221; materials are also discussed. We further describe how these materials can be used as a tool to inhibit pathogen mediated cytotoxicity and discuss scope, limitations and further applications of this approach in studying bacterial - host interactions.

Bacterial attachment to host cells is a key step during host colonization and infection. This protocol describes the generation of polymer-coupled recombinant adhesins as biomimetic materials which allow analysis of the contribution of individual adhesins to these processes, independent of other bacterial factors.

仿生材料表征细菌宿主相互作用

Bacterial attachment to host cells is one of the earliest events during bacterial colonization of host tissues and thus a key step during infection. The ...

免疫与感染

Analysis of Transforming Growth Factor &#223; Family Cleavage Products Secreted Into the Blastocoele of Xenopus laevis Embryos

The two arms of the Transforming Growth Factor &#223; (Tgf&#223;) superfamily, represented by Tgf&#223;/Nodal or Bone morphogenetic protein (Bmp) ligands, respectively, play essential roles in embryonic development and adult homeostasis. Members of the Tgf&#223; family are made as inactive precursors that dimerize and fold within the endoplasmic reticulum. The precursor is subsequently cleaved into ligand and prodomain fragments. Although only the dimeric ligand can engage Tgf&#223; receptors and activate downstream signaling, there is growing recognition that the prodomain moiety contributes to ligand activity. This article describes a protocol that can be used to identify cleavage products generated during activation of Tgf&#223; precursor proteins. RNA encoding Tgf&#223; precursors are first microinjected into X. laevis embryos. The following day, cleavage products are collected from the blastocoele of&#160;gastrula stage embryos and analyzed on Western blots. This protocol can be completed relatively quickly, does not require expensive reagents and provides a source of concentrated Tgf&#223; cleavage products under physiologic conditions.

Analysis of Transforming Growth Factor &#223; Family Cleavage Products Secreted Into the Blastocoele of Xenopus laevis Embryos

When Transforming Growth Factor &#223; family precursor proteins are ectopically expressed in Xenopus laevis embryos, they dimerize, get cleaved and are secreted into the blastocoele, which begins at the late blastula to early gastrula stage. We describe a method for aspirating cleavage products from the blastocoele cavity for immunoblot analysis.

转变生长因子的分析 - 家族产品分泌到 异种胚胎 的爆炸

The two arms of the Transforming Growth Factor &#223; (Tgf&#223;) superfamily, represented by Tgf&#223;/Nodal or Bone morphogenetic protein (Bmp) ligands, ...

发育生物学

Site-Directed Immobilization of Bone Morphogenetic Protein 2 to Solid Surfaces by Click Chemistry

Different therapeutic strategies for the treatment of non-healing long bone defects have been intensively investigated. Currently used treatments present several limitations that have led to the use of biomaterials in combination with osteogenic growth factors, such as bone morphogenetic proteins (BMPs). Commonly used absorption or encapsulation methods require supra-physiological amounts of BMP2, typically resulting in a so-called initial burst release effect that provokes several severe adverse side effects. A possible strategy to overcome these problems would be to covalently couple the protein to the scaffold. Moreover, coupling should be performed in a site-specific manner in order to guarantee a reproducible product outcome. Therefore, we created a BMP2 variant, in which an artificial amino acid (propargyl-L-lysine) was introduced into the mature part of the BMP2 protein by codon usage expansion (BMP2-K3Plk). BMP2-K3Plk was coupled to functionalized beads through copper catalyzed azide-alkyne cycloaddition (CuAAC). The biological activity of the coupled BMP2-K3Plk was proven in vitro and the osteogenic activity of the BMP2-K3Plk-functionalized beads was proven in cell based assays. The functionalized beads in contact with C2C12 cells were able to induce alkaline phosphatase (ALP) expression in locally restricted proximity of the bead. Thus, by this technique, functionalized scaffolds can be produced that can trigger cell differentiation towards an osteogenic lineage. Additionally, lower BMP2 doses are sufficient due to the controlled orientation of site-directed coupled BMP2. With this method, BMPs are always exposed to their receptors on the cell surface in the appropriate orientation, which is not the case if the factors are coupled via non-site-directed coupling techniques. The product outcome is highly controllable and, thus, results in materials with homogeneous properties, improving their applicability for the repair of critical size bone defects.

Biomaterials doped with Bone Morphogenetic Protein 2 (BMP2) have been used as a new therapeutic strategy to heal non-union bone fractures. To overcome side effects resulting from an uncontrollable release of the factor, we propose a new strategy to site-directly immobilize the factor, thus creating materials with improved osteogenic capabilities.

点化学法现场定向固定骨形态发生蛋白2到固体表面

Different therapeutic strategies for the treatment of non-healing long bone defects have been intensively investigated. Currently used treatments present ...

生物工程

聚合物接枝金属有机框架单层的自组装

Synthesis and Characterization of Self-Assembled Metal-Organic Framework Monolayers Using Polymer-Coated Particles

Metal-organic frameworks (MOFs) are materials with potential applications in fields such as gas adsorption and separation, catalysis, and biomedicine. Attempts to enhance the utility of MOFs have involved the preparation of various composites, including polymer-grafted MOFs. By directly grafting polymers to the external surface of MOFs, issues of incompatibility between polymers and MOFs can be overcome. Polymer brushes grafted from the surface of MOFs can serve to stabilize the MOF while enabling particle assembly into self-assembled metal-organic framework monolayers (SAMMs) via polymer-polymer interactions.
Control over the chemical composition and molecular weight of the grafted polymer can allow for tuning of the SAMM characteristics. In this work, instructions are provided on how to immobilize a chain transfer agent (CTA) onto the surface of the MOF UiO-66 (UiO = Universitetet i Oslo). The CTA&#160;serves as initiation sites for the growth of polymers. Once polymer chains are grown from the MOF surface, the formation of SAMMs is achieved through self-assembly at an air-water interface. The resulting SAMMs are characterized and shown to be freestanding by scanning electron microscopy imaging. The methods presented in this paper are expected to make the preparation of SAMMs more accessible to the research community and thereby expand their potential use as a&#160;MOF-polymer composite.

作者聚焦:探索自组装的 MOF-聚合物复合材料

A protocol for the synthesis and characterization of self-assembled metal-organic framework monolayers is provided using polymer-grafted, metal-organic framework (MOF) crystals. The procedure shows that polymer-grafted MOF particles can be self-assembled at an air-water interface resulting in well-formed, free-standing, monolayer structures as evidenced by scanning electron microscopy imaging.

使用聚合物包覆颗粒的自组装金属有机框架单层的合成和表征

Metal-organic frameworks (MOFs) are materials with potential applications in fields such as gas adsorption and separation, catalysis, and biomedicine. ...