Ce travail a été soutenu par un financement fourni par le Bureau de la recherche navale. J. Fontana reconnaît le Conseil national de recherches pour un associateship postdoctoral.

1. Monocouches auto-assemblées ligand nanoparticules A titre d&#39;exemple illustratif de la technique d&#39;auto-assemblage, macroscopiques, coiffées films monocouches nanosphères d&#39;or alcane-thiols sont produites comme suit: <ol><li> Concentré nanosphères 15 nm d&#39;or (disponibles dans le commerce à une densité en nombre: 10 12 particules / ml) à ~ 10 13 particules / ml dans de l&#39;eau. <ol><li> Placer 15 ml de la suspension aqueuse diluée de nanosphères dans un filtre centrifuge ultra (100 K de limite nominale du poids moléculaire). </li><li> Centrifuger le filtre / flacon à 4500 x g pendant 2 minutes, ou jusqu&#39;à ce que seulement quelques ml restent dans la chambre de filtration. </li></ol></li><li> Remettre en suspension dans la nanosphère environ 1 ml d&#39;eau désionisée (DI) de l&#39;eau de telle sorte que la concentration des nanoparticules est de 10 13 particules / ml. La suspension est stable pendant plusieurs heures une fois remises en suspension dans de l&#39;eau DI. <ol><li> Vérifier la densité de nombre et de confirmer les nanoparticules haavez pas agrégées. Diluer la suspension de nanoparticules concentré par un facteur de 1:10 retour à la concentration initiale en plaçant 0,150 ml de la suspension dans une cuve (1 cm de longueur de trajet), et à cette ajouter 1,35 ml d&#39;eau DI. </li><li> Placer la cuvette dans un spectromètre et mesurer le spectre de la suspension et la suspension d&#39;origine absorbance. Comparer la position de crête et la largeur à mi-hauteur pour assurer une agrégation n&#39;a pas eu lieu. L&#39;amplitude des pics d&#39;absorbance pour les deux échantillons doit être approximativement la même, assurant ainsi l&#39;échantillon concentré est plus dense par un facteur de 10. </li></ol></li><li> Dans un flacon en verre propre de 20 ml de borosilicate séparée ajouter 1 ml de tétrahydrofurane (THF). </li><li> Ajouter les ligands thiol-alcanes (par exemple 5 ml de 1,6-hexanedithiol et 5 ml de 1-dodécanethiol) pour le THF et agiter la solution pour mélanger uniformément. Ligand Assez doit être ajouté afin de couvrir au moins toute la surface des nanoparticules en suspension. Excess ligand augmente la vitesse et l&#39;efficacité de la réaction. </li><li> Dans une hotte, verser le contenu de la fiole contenant les nanosphères d&#39;or dans le flacon de THF-ligands. </li><li> Visser le plus vite sur le couvercle et secouer vigoureusement le flacon pendant 15 secondes. </li><li> Retirer le couvercle et mettre le flacon dans la hotte, la figure 1 (a). En fonction des ligands utilisés, les domaines des films de nanoparticules d&#39;or forment rapidement à l&#39;interface air-liquide, la figure 1 (c). Les films sont alors commencer à traduire les côtés de la cuvette, la figure 1 (d). Presque tous les nanoparticules sont coiffés avec un groupe thiol du ligand, retiré de la suspension, et transportées vers les côtés de la fiole à l&#39;intérieur de 1 h, la figure 1 (e). </li></ol> 2. Transfert des monocouches sur des substrats amovibles <ol><li> Pour transférer les films sur verre amovible et de silicium des substrats de plaquettes: couper les substrats dans une zone de 12,5 mm x 25,4 mm en utilisant unstylo de traçage / roue. <ol><li> Verre Supports: Nettoyer à l&#39;aide d&#39;un rinçage à l&#39;acétone, suivi d&#39;un rinçage à l&#39;alcool isopropylique, et enfin un rinçage à l&#39;eau déminéralisée. Laissez les substrats à sécher, passez à la section 2.2. </li><li> Silicon Wafer supports: dans une hotte préparer la solution Piranha (3 parties d&#39;acide sulfurique concentré à une partie de 30% de peroxyde d&#39;hydrogène, ATTENTION: comburant, corrosif). Placer 15 ml d&#39;acide sulfurique dans un flacon de 20 ml en verre de borosilicate. Pour cette ajouter lentement 5 ml de 30% de peroxyde d&#39;hydrogène. Ne pas boucher le flacon. Faites preuve de prudence; le mélange est fortement exothermique. Voir la référence pour plus d&#39;informations de sécurité 19. </li><li> Plonger délicatement les substrats de plaquettes de silicium dans une solution Piranha pendant 30 min, retirer, rincer avec de l&#39;eau DI et sec avec de l&#39;azote. </li><li> A titre d&#39;étape facultative, le flacon utilisé pour l&#39;échange de ligand des nanoparticules et de l&#39;auto-assemblage peut être salinisée à forcer tous les nanoparticules sur le substrat de verre ou silicon tranche au lieu des murs de la fiole de verre, sinon passez à la section 2.2. </li><li> Remplir le flacon en verre avec une solution piranha (ATTENTION: comburant, corrosif), reportez-vous à la section 2.1.2. </li><li> Amener le flacon à tremper pendant 30 min. Après 30 minutes rincer le flacon avec de l&#39;eau déminéralisée. </li><li> Remplir le flacon avec 1% v / v de l&#39;hexaméthyldisilazane dans l&#39;acétone et le capuchon. </li><li> Laisser le flacon scellé à tremper pendant 24 heures, puis rincer avec de l&#39;eau DI et sec avec de l&#39;azote. </li></ol></li><li> Avant agitation (section 1.6), insérez le support dans le flacon. Visser le couvercle et secouer. </li><li> Après avoir secoué retirer le couvercle et, en utilisant des pinces, placer le substrat presque verticale contre la paroi du flacon. </li><li> Utiliser une pipette pour enrober le mélange de réaction sur le substrat. La réaction s&#39;arrête lorsque tout le solvant organique est évaporé ou tous les nanoparticules ont été retirés de la suspension. </li></ol> 3. Analyse monocouche <ol><li> Estimer laemballer l&#39;efficacité des nanosphères dans la monocouche rapidement en observant la transmission et des propriétés de réflexion du film. Éclairer la monocouche sur substrats de verre par derrière avec une source de lumière blanche. Avec une source de lumière blanche, un film de couleur uniforme doit être observée pour la haute densité des films monocouches de nanoparticules dans la transmission et la réflexion d&#39;or comme observé dans la réflexion, la figure 2. </li><li> Utilisez un spectromètre (voir section 1.2.2) afin de quantifier le spectre d&#39;absorption macroscopique des monocouches, la figure 4. Normaliser le spectre d&#39;absorption avec une lame de verre propre. Monter le film monocouche, sur un substrat de verre, dans le trajet des rayons du spectromètre et de collecter le spectre d&#39;absorbance. Remarque: le pic d&#39;absorbance doit être nettement décalées vers le rouge de plusieurs centaines de nanomètres en fonction du ligand utilisé. Le facteur de qualité du pic d&#39;absorbance doit être comparable à la valeur de la suspension diluée, mais seulement légèrement broadened (Figure 4). Si le pic d&#39;absorption est très large ou pas bien défini alors les films monocouches sont probablement de mauvaise qualité, passez à la section 3.3 pour une caractérisation plus poussée. </li><li> Examiner la structure nanoscopique des nanosphères en utilisant la microscopie électronique à balayage (MEB) de monocouches transférées sur des substrats de plaquettes de silicium (voir section 2.1.2), comme illustré sur la figure 3. Lorsque les films sont sur ​​le verre des substrats se connectent bande conductrice à l&#39;un des coins de la feuille et la terre au pied SEM pour éviter les charges et permettre l&#39;imagerie. </li></ol> 4. Technique de transfert de phase efficace pour organiques solubles nanoparticules <ol><li> Pour utiliser la technique comme un moyen efficace pour fonctionnaliser les nanoparticules avec des ligands thiols, décanter la solution restante à partir du fond de la fiole une fois la réaction terminée, la section 1.7, et sécher le matériau dans le flacon sous atmosphère d&#39;azote. </li><li> Ajouter un solvant organique (par exemple,le chloroforme, le toluène) à remettre en suspension les nanoparticules avec près de 100% de transfert de phase et la récupération des particules. </li><li> Répétez la section 1.2.1 pour s&#39;assurer que les nanoparticules ne sont pas agrégées sur la remise en suspension dans le solvant organique. Si le pic d&#39;absorbance est le panneau, par rapport à la suspension d&#39;origine, sonication de l&#39;échantillon pendant 15 min à l&#39;aide redisperser les nanoparticules, la figure 4. </li></ol>

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Les auteurs n&#39;ont rien à révéler.

Ce protocole décrit une seule «one-pot» technique d&#39;auto-assemblage pour créer macroscopiques films monocouches de nanoparticules ligand par transfert de phase, la séparation de phase et des gradients de tension de surface. L&#39;avantage de cette technique est qu&#39;elle combine trois processus d&#39;auto-assemblage dans un seul processus, à faible coût; par éliminer rapidement et efficacement le transfert des nanoparticules, l&#39;assemblage des particules dans des monocouches à l&#39;interface air-liqui...

L&#39;auto-assemblage de films de nanoparticules macroscopiques a attiré une grande attention pour leurs propriétés uniques, déterminées à partir de la géométrie et la composition des éléments 5 et peut conduire à une large gamme d&#39;applications optiques, électroniques et chimiques 14.6. Pour ces films auto-assemblage de nanoparticules métalliques coiffés de ligands doivent être emballés dans de haute densité, monocouches. Toutefois, plusieurs questions d&#39;assemblage doivent être abordées pour faire avancer le développement de ces matériaux. Tout d&#39;abord, tensioactif stabilisé nanoparticules métalliques sont généralement synthétisés par voie humide-chimie dans les suspensions diluées 15. Pour éviter l&#39;agrégation et pour contrôler l&#39;espacement interparticulaire des nanoparticules dans les films, les nanoparticules ont besoin d&#39;être coiffé avec des coquilles de ligands. Après les nanoparticules ont été fonctionnalisé avec des ligands les nanoparticules restent habituellement dans des suspensions relativement diluées. Une technique est alors neEDED à s&#39;auto-assembler des nanoparticules dans macroscopiques, à haute densité, des films monocouches 16, 17. Cheng et al. 18 phases transféré nanotubes d&#39;or en utilisant du polystyrène thiolée dans une suspension tétrahydrofuranne-eau. Les nanotubes ont été ensuite remises en suspension dans du chloroforme et une goutte a été placée à l&#39;interface air-eau et on évapore lentement, en formant des films monocouches. Bigioni et al. 17 créé monocouches macroscopiques de DODECANETHIOL plafonné nanosphères d&#39;or à l&#39;aide de l&#39;excès de ligand et l&#39;évaporation du solvant rapide, mais les nanosphères nécessaire pour être transféré avant la phase d&#39;auto-assemblage. Une fois que les films monocouches sont formées dont ils ont besoin généralement d&#39;être transportés sur un substrat. Mayya et al. Nanosphères 3 confiné à une interface eau-toluène et les a transférés sur des substrats modèles de libre-en utilisant des gradients de tension superficielle. De même, Johnson <em&gt; et al. quatre nanosphères d&#39;argent en suspension dans un excès de ligand et ensuite convertis en les nanoparticules les parois de la fiole en utilisant des gradients de tension de surface à partir de deux fluides non miscibles. Bien que les techniques d&#39;assemblage existent pour répondre à chacune de ces questions, le besoin de techniques plus efficaces est nécessaire pour aider au développement de la production de film de nanoparticules à grande échelle. Ici, nous démontrons une technique simple et robuste qui combine les trois questions d&#39;auto-assemblage décrits ci-dessus en un seul «one-pot» technique, illustré à la figure 1. Un solvant organique miscible (par exemple le tétrahydrofuranne, sulfoxyde dimeythl), est utilisé pour d&#39;abord rapidement et efficacement fonctionnaliser thiol-ligands (par exemple thiol-alcanes, thiol-ène, thiol-phénols) sur les nanoparticules (par exemple, des nanosphères d&#39;or, des nanotubes, etc.) Le mélange entraîne alors l&#39;auto-assemblage de nanoparticules dans macroscopique, haute densité, Monolayer films à l&#39;interface air-liquide à l&#39;aide de la séparation de phase. Enfin, les films monocouches de nanoparticules forment une connexion sur des substrats à l&#39;aide de modèles, des gradients de tension de surface à partir de la / le mélange de solvant organique de l&#39;eau, la figure 2 et la figure 3.

<table border="0" cellpadding="0" cellspacing="0" width="628">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:224px;">1-6 hexanedithiol</td>
			<td style="width:97px;">Sigma</td>
			<td style="width:140px;">H12005-5G</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:224px;">1-dodecanethiol</td>
			<td style="width:97px;">Sigma</td>
			<td style="width:140px;">471364-100ML</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:224px;">20 ml liquid scintillation vials</td>
			<td style="width:97px;">Sigma</td>
			<td style="width:140px;">Z253081-1PAK</td>
			<td></td>
		</tr>
		<tr height="24">
			<td height="24" style="height:25px;width:224px;">acetone</td>
			<td style="width:97px;">Sigma</td>
			<td>650501-1L</td>
			<td></td>
		</tr>
		<tr height="24">
			<td height="24" style="height:24px;width:224px;">amicon ultra-15 centrifugal filter&#160;</td>
			<td style="width:97px;">Millipore</td>
			<td style="width:140px;">100K</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:224px;">centrifuge</td>
			<td style="width:97px;">Sorvall&#160;</td>
			<td style="width:140px;">RC5B</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:224px;">centrifuge&#160;</td>
			<td style="width:97px;">Eppendorf</td>
			<td style="width:140px;">5810R</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:224px;">deionized water&#160;</td>
			<td style="width:97px;">in-house&#39;</td>
			<td style="width:140px;">N/A</td>
			<td></td>
		</tr>
		<tr height="24">
			<td height="24" style="height:25px;width:224px;">glass slides</td>
			<td style="width:97px;">Sigma</td>
			<td style="width:140px;">CLS294875X25-72EA</td>
			<td></td>
		</tr>
		<tr height="24">
			<td height="24" style="height:24px;width:224px;">15 nm gold nanospheres</td>
			<td style="width:97px;">Ted Pella, Inc</td>
			<td style="width:140px;">15703-1</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:224px;">hexamethyldisilazane</td>
			<td style="width:97px;">Sigma</td>
			<td style="width:140px;">52619-50ML</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:224px;">hydrogen peroxide (30%)</td>
			<td style="width:97px;">Sigma</td>
			<td style="width:140px;">216763-100ML</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:224px;">scanning electron microscope</td>
			<td style="width:97px;">Carl Zeiss</td>
			<td style="width:140px;">Model 55</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:224px;">polished silicon wafer</td>
			<td style="width:97px;">Sun Edison</td>
			<td style="width:140px;">N/A</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:224px;">spectrometer</td>
			<td style="width:97px;">OceanOptics</td>
			<td style="width:140px;">USB4000-VIS-NIR</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:224px;">sulfuric acid</td>
			<td style="width:97px;">Fisher</td>
			<td style="width:140px;">A300-212</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:224px;">tetrahydrofuran</td>
			<td style="width:97px;">Sigma</td>
			<td style="width:140px;">401757-100ML</td>
			<td></td>
		</tr>
	</tbody>
</table>

a technique to functionalize and self-assemble macroscopic nanoparticle-ligand monolayer films onto template-free substrates

Ce protocole décrit une technique d&#39;auto-assemblage pour créer des films monocouches macroscopiques composés de nanoparticules revêtues de ligands 1, 2. La technique simple, robuste et évolutive fonctionnalise efficacement nanoparticules métalliques avec des ligands thiols dans un mélange eau / solvant organique miscible permettant le greffage rapide de groupes thiol sur la surface des nanoparticules d&#39;or. Les ligands hydrophobes sur les nanoparticules puis rapidement la phase de séparer les nanoparticules de la suspension de base aqueuse et les confinent à l&#39;interface air-liquide. Ceci entraîne les nanoparticules de ligands à coiffe pour former des domaines en monocouche à l&#39;interface air-liquide. L&#39;utilisation de solvants organiques miscibles à l&#39;eau est importante car elle permet le transport des nanoparticules à partir de l&#39;interface de connexion sur des substrats modèles. Le débit est médiée par une surface gradient de tension 3, 4 et crée macroscopique, à haute densité, monocouche nanopfilms d&#39;articles-ligand. Cette technique d&#39;auto-assemblage peut être généralisé pour inclure l&#39;utilisation de particules de compositions différentes, la taille et la forme et peut conduire à un procédé d&#39;assemblage efficace de produire des films à faible coût, macroscopiques, à haute densité, monocouche de nanoparticules pour des applications répandues .

La figure 1 (a) montre une suspension de nanosphères d&#39;or, des ligands de type thiol-alcanes, le tétrahydrofuranne et l&#39;eau dans un flacon de verre immédiatement après le mélange. Un schématique des trois étapes principales d&#39;auto-assemblage, le transfert de phase, la séparation de phases, et la surface gradient de tension à médiation transport de film est représenté sur la figure 1 (b) en tant que vue développée à l&#39;interface air-liquide à proximité de ...

Watch this Scientific Journal Video about A Technique to Functionalize and Self-assemble Macroscopic Nanoparticle-ligand Monolayer Films onto Template-free Substrates at JoVE.com

A Technique to Functionalize and Self-assemble Macroscopic Nanoparticle-ligand Monolayer Films onto Template-free Substrates

Une technique simple, robuste et évolutive pour fonctionnaliser et s&#39;auto-assembler macroscopiques monocouche films de nanoparticules sur des substrats ligand libre-modèle est décrit dans le présent protocole.

Une technique pour fonctionnaliser et auto-assemblage de nanoparticules macroscopiques-ligand monocouches Films sur substrats libre-modèle

This protocol describes a self-assembly technique to create macroscopic monolayer films composed of ligand-coated nanoparticles1,2. The simple, robust and ...

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Research

JoVE Journal

Chemistry

10.8K vues.  Naval Research Laboratory.  Une technique simple, robuste et évolutive pour fonctionnaliser et s'auto-assembler macroscopiques monocouche films de nanoparticules sur des substrats ligand libre-modèle est décrit dans le présent protocole. 

Vidéo: A Technique to Functionalize and Self-assemble Macroscopic Nanoparticle-ligand Monolayer Films onto Template-free Substrates

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

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 differentiation into osteoblasts, thus stimulating healing and de novo bone formation. The clinical use of recombinant human BMP-2 (rhBMP-2) in conjunction with scaffolds has raised recent controversies, based on the mode of presentation and the amount to be delivered. The protocol presented here provides a simple and efficient way to deliver BMP-2 for in vitro studies on cells. We describe how to form a self-assembled monolayer consisting of a heterobifunctional linker, and show the subsequent binding step to obtain covalent immobilization of rhBMP-2. With this approach it is possible to achieve a sustained presentation of BMP-2 while maintaining the biological activity of the protein. In fact, the surface immobilization of BMP-2 allows targeted investigations by preventing unspecific adsorption, while reducing the amount of growth factor and, most notably, hindering uncontrolled release from the surface. Both short- and long-term signaling events triggered by BMP-2 are taking place when cells are exposed to surfaces presenting covalently immobilized rhBMP-2, making this approach suitable for in vitro studies on cell responses to BMP-2 stimulation.

We describe a method for accomplishing efficient immobilization of BMP-2 on surfaces. Our approach is based on the formation of a self-assembled monolayer to achieve the covalent binding of BMP-2 via its free amine residues. This method is a useful tool to study signaling at the cell membrane.

Liaison covalente de BMP-2 sur les surfaces en utilisant une approche monocouche auto-assemblée

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 ...

Recherche

Chimie

Towards Biomimicking Wood: Fabricated Free-standing Films of Nanocellulose, Lignin, and a Synthetic Polycation

Woody materials are comprised of plant cell walls that contain a layered secondary cell wall composed of structural polymers of polysaccharides and lignin. Layer-by-layer (LbL) assembly process which relies on the assembly of oppositely charged molecules from aqueous solutions was used to build a freestanding composite film of isolated wood polymers of lignin and oxidized nanofibril cellulose (NFC). To facilitate the assembly of these negatively charged polymers, a positively charged polyelectrolyte, poly(diallyldimethylammomium chloride) (PDDA), was used as a linking layer to create this simplified model cell wall. The layered adsorption process was studied quantitatively using quartz crystal microbalance with dissipation monitoring (QCM-D) and ellipsometry. The results showed that layer mass/thickness per adsorbed layer increased as a function of total number of layers. The surface coverage of the adsorbed layers was studied with atomic force microscopy (AFM). Complete coverage of the surface with lignin in all the deposition cycles was found for the system, however, surface coverage by NFC increased with the number of layers. The adsorption process was carried out for 250 cycles (500 bilayers) on a cellulose acetate (CA) substrate. Transparent free-standing LBL assembled nanocomposite films were obtained when the CA substrate was later dissolved in acetone. Scanning electron microscopy (SEM) of the fractured cross-sections showed a lamellar structure, and the thickness per adsorption cycle (PDDA-Lignin-PDDA-NC) was estimated to be 17 nm for two different lignin types used in the study. The data indicates a film with highly controlled architecture where nanocellulose and lignin are spatially deposited on the nanoscale (a polymer-polymer nanocomposites), similar to what is observed in the native cell wall.

The objective of this research was to form synthetic plant cell wall tissue using layer-by-layer assembly of nanocellulose fibrils and isolated lignin assembled from dilute aqueous suspensions.&#160; Surface measurement techniques of quartz crystal microbalance and atomic force microscopy were used to monitor the formation of the polymer-polymer nanocomposite material.

Vers Biomimicking Bois: Films Fabrication libre-debout de nanocellulose, lignine, et un polycation synthétique

Woody materials are comprised of plant cell walls that contain a layered secondary cell wall composed of structural polymers of polysaccharides and ...

Atomically Defined Templates for Epitaxial Growth of Complex Oxide Thin Films

Atomically defined substrate surfaces are prerequisite for the epitaxial growth of complex oxide thin films. In this protocol, two approaches to obtain such surfaces are described. The first approach is the preparation of single terminated perovskite SrTiO3 (001) and DyScO3 (110) substrates. Wet etching was used to selectively remove one of the two possible surface terminations, while an annealing step was used to increase the smoothness of the surface. The resulting single terminated surfaces allow for the heteroepitaxial growth of perovskite oxide thin films with high crystalline quality and well-defined interfaces between substrate and film. In the second approach, seed layers for epitaxial film growth on arbitrary substrates were created by Langmuir-Blodgett (LB) deposition of nanosheets. As model system Ca2Nb3O10- nanosheets were used, prepared by delamination of their layered parent compound HCa2Nb3O10. A key advantage of creating seed layers with nanosheets is that relatively expensive and size-limited single crystalline substrates can be replaced by virtually any substrate material.

Various procedures are outlined to prepare atomically defined templates for epitaxial growth of complex oxide thin films. Chemical treatments of single crystalline SrTiO3 (001) and DyScO3 (110) substrates were performed to obtain atomically smooth, single terminated surfaces. Ca2 Nb3 O10- nanosheets were used to create atomically defined templates on arbitrary substrates.

Modèles atomique définies pour croissance épitaxiale d&#39;oxyde complexe couches minces

Atomically defined substrate surfaces are prerequisite for the epitaxial growth of complex oxide thin films. In this protocol, two approaches to obtain ...

Fabrication of Large-area Free-standing Ultrathin Polymer Films

This procedure describes a method for the fabrication of large-area and ultrathin free-standing polymer films. Typically, ultrathin films are prepared using either sacrificial layers, which may damage the film or affect its mechanical properties, or they are made on freshly cleaved mica, a substrate that is difficult to scale. Further, the size of ultrathin film is typically limited to a few square millimeters. In this method, we modify a surface with a polyelectrolyte that alters the strength of adhesion between polymer and deposition substrate. The polyelectrolyte can be shown to remain on the wafer using spectroscopy, and a treated wafer can be used to produce multiple films, indicating that at best minimal amounts of the polyelectrolyte are added to the film. The process has thus far been shown to be limited in scalability only by the size of the coating equipment, and is expected to be readily scalable to industrial processes. In this study, the protocol for making the solutions, preparing the deposition surface, and producing the films is described.

We describe a method for the fabrication of large-area (up to 13 cm diameter) and ultrathin (as thin as 8 nm) polymer films. Instead of using a sacrificial interlayer to delaminate the film from its substrate, we use a self-limiting surface treatment suitable for arbitrarily large areas.

Fabrication de grande Zone de libre-debout ultraminces films polymères

This procedure describes a method for the fabrication of large-area and ultrathin free-standing polymer films.  Typically, ultrathin films are prepared ...

Preparation of Mica and Silicon Substrates for DNA Origami Analysis and Experimentation

The designed nature and controlled, one-pot synthesis of DNA origami provides exciting opportunities in many fields, particularly nanoelectronics. Many of these applications require interaction with and adhesion of DNA nanostructures to a substrate. Due to its atomically flat and easily cleaned nature, mica has been the substrate of choice for DNA origami experiments. However, the practical applications of mica are relatively limited compared to those of semiconductor substrates. For this reason, a straightforward, stable, and repeatable process for DNA origami adhesion on derivatized silicon oxide is presented here. To promote the adhesion of DNA nanostructures to silicon oxide surface, a self-assembled monolayer of 3-aminopropyltriethoxysilane (APTES) is deposited from an aqueous solution that is compatible with many photoresists. The substrate must be cleaned of all organic and metal contaminants using Radio Corporation of America (RCA) cleaning processes and the native oxide layer must be etched to ensure a flat, functionalizable surface. Cleanrooms are equipped with facilities for silicon cleaning, however many components of DNA origami buffers and solutions are often not allowed in them due to contamination concerns. This manuscript describes the set-up and protocol for in-lab, small-scale silicon cleaning for researchers who do not have access to a cleanroom or would like to incorporate processes that could cause contamination of a cleanroom CMOS clean bench. Additionally, variables for regulating coverage are discussed and how to recognize and avoid common sample preparation problems is described.

Reproducible cleaning processes for substrates used in DNA origami research are described, including bench-top RCA cleaning and derivatization of silicon oxide. Protocols for surface preparation, DNA origami deposition, drying parameters, and simple experimental set-ups are illustrated.

Préparation de Mica et Silicon substrats pour l&#39;ADN Origami Analyse et Expérimentation

The designed nature and controlled, one-pot synthesis of DNA origami provides exciting opportunities in many fields, particularly nanoelectronics. Many of ...

Cooling Rate Dependent Ellipsometry Measurements to Determine the Dynamics of Thin Glassy Films

This report aims to fully describe the experimental technique of using ellipsometry for cooling rate dependent Tg (CR-Tg) experiments. These measurements are simple high-throughput characterization experiments, which can determine the glass transition temperature (Tg), average dynamics, fragility and the expansion coefficient of the super-cooled liquid and glassy states for a variety of glassy materials. This technique allows for these parameters to be measured in a single experiment, while other methods must combine a variety of different techniques to investigate all of these properties. Measurements of dynamics close to Tg are particularly challenging. The advantage of cooling rate dependent Tg measurements over other methods which directly probe bulk and surface relaxation dynamics is that they are relatively quick and simple experiments, which do not utilize fluorophores or other complicated experimental techniques. Furthermore, this technique probes the average dynamics of technologically relevant thin films in temperature and relaxation time (&#964;&#945;) regimes relevant to the glass transition (&#964;&#945; &#62; 100 sec). The limitation to using ellipsometry for cooling rate dependent Tg experiments is that it cannot probe relaxation times relevant to measurements of viscosity (&#964;&#945; &#60;&#60; 1 sec). Other cooling rate dependent Tg measurement techniques, however, can extend the CR-Tg method to faster relaxation times. Furthermore, this technique can be used for any glassy system so long as the integrity of the film remains throughout the experiment.

Here, we present a protocol for cooling rate dependent ellipsometry experiments, which can determine the glass transition temperature (Tg), average dynamics, fragility and the expansion coefficient of the super-cooled liquid and glass for a variety of glassy materials.

La vitesse de refroidissement à charge Dimensions Ellipsométrie à déterminer la dynamique de Thin Films vitreux

This report aims to fully describe the experimental technique of using ellipsometry for cooling rate dependent Tg (CR-Tg) experiments. These measurements ...

Deacetylation Assays to Unravel the Interplay between Sirtuins (SIRT2) and Specific Protein-substrates

Acetylation has emerged as an important post-translational modification (PTM) regulating a plethora of cellular processes and functions. This is further supported by recent findings in high-resolution mass spectrometry based proteomics showing that many new proteins and sites within these proteins can be acetylated. However the identity of the enzymes regulating these proteins and sites is often unknown. Among these enzymes, sirtuins, which belong to the class III histone lysine deacetylases, have attracted great interest as enzymes regulating the acetylome under different physiological or pathophysiological conditions. Here we describe methods to link SIRT2, the cytoplasmic sirtuin, with its substrates including both in vitro and in vivo deacetylation assays. These assays can be applied in studies focused on other members of the sirtuin family to unravel the specific role of sirtuins and are necessary in order to establish the regulatory interplay of specific deacetylases with their substrates as a first step to better understand the role of protein acetylation. Furthermore, such assays can be used to distinguish functional acetylation sites on a protein from what may be non-regulatory acetylated lysines, as well as to examine the interplay between a deacetylase and its substrate in a physiological context.

Deacetylation Assays to Unravel the Interplay between Sirtuins SIRT2 and Specific Protein-substrates

This protocol describes the required steps to execute in vitro and in vivo deacetylation assays in order to establish the role of proteins as specific deacetylation substrates for sirtuins and further study the role of reversible - lysine acetylation as a post-translational modification.

Désacétylation essais pour démêler les Interplay entre sirtuines (SIRT2) et protéines substrats spécifiques

Acetylation has emerged as an important post-translational modification (PTM) regulating a plethora of cellular processes and functions. This is further ...

Capillary Electrophoresis to Monitor Peptide Grafting onto Chitosan Films in Real Time

Free-solution capillary electrophoresis (CE) separates analytes, generally charged compounds in solution through the application of an electric field. Compared to other analytical separation techniques, such as chromatography, CE is cheap, robust and effectively requires no sample preparation (for a number of complex natural matrices or polymeric samples). CE is fast and can be used to follow the evolution of mixtures in real time (e.g., chemical reaction kinetics), as the signals observed for the separated compounds are directly proportional to their quantity in solution.
Here, the efficiency of CE is demonstrated for monitoring the covalent grafting of peptides onto chitosan films for subsequent biomedical applications. Chitosan&#39;s antimicrobial and biocompatible properties make it an attractive material for biomedical applications such as cell growth substrates. Covalently grafting the peptide RGDS (arginine - glycine - aspartic acid - serine) onto the surface of chitosan films aims at improving cell attachment. Historically, chromatography and amino acid analysis have been used to provide a direct measurement of the amount of grafted peptide. However, the fast separation and absence of sample preparation provided by CE enables equally accurate yet real-time monitoring of the peptide grafting process. CE is able to separate and quantify the different components of the reaction mixture: the (non-grafted) peptide and the chemical coupling agents. In this way the use of CE results in improved films for downstream applications.
The chitosan films were characterized through solid-state NMR (nuclear magnetic resonance) spectroscopy. This technique is more time-consuming and cannot be applied in real time, but yields a direct measurement of the peptide and thus validates the CE technique.

Free solution capillary electrophoresis is a fast, cheap and robust analytical method that enables the quantitative monitoring of chemical reactions in real time. Its utility for rapid, convenient and precise analysis is demonstrated here through analysis of covalent peptide grafting onto chitosan films for improved cell adhesion.

Electrophorèse Capillaire pour surveiller Peptide greffant sur chitosan Films en temps réel

Free-solution capillary electrophoresis (CE) separates analytes, generally charged compounds in solution through the application of an electric field. ...

Reactive Vapor Deposition of Conjugated Polymer Films on Arbitrary Substrates

We demonstrate a method of conformally coating conjugated polymers on arbitrary substrates using a custom-designed, low-pressure reaction chamber. Conductive polymers, poly(3,4-ethylenedioxythiophene) (PEDOT) and poly(3,4-propylenedioxythiophene) (PProDOT), and a semiconducting polymer, poly(thieno[3,2-b]thiophene) (PTT), were deposited on unconventional highly-disordered and textured substrates with high surface areas, such as paper, towels and fabrics. This reported deposition chamber is an improvement of previous vapor reactors because our system can accommodate both volatile and nonvolatile monomers, such as 3,4-propylenedioxythiophene and thieno[3,2-b]thiophene. Utilization of both solid and liquid oxidants are also demonstrated. One limitation of this method is that it lacks sophisticated in situ thickness monitors. Polymer coatings made by the commonly used solution-based coating methods, such as spin-coating and surface grafting, are often not uniform or susceptible to mechanical degradation. This reported vapor phase deposition method overcomes those drawbacks and is a strong alternative to common solution-based coating methods. Notably, polymer films coated by the reported method are uniform and conformal on rough surfaces, even at a micrometer scale. This feature allows for future application of vapor deposited polymers in electronics devices on flexible and highly textured substrates.

This paper presents a protocol for reactive vapor deposition of poly(3,4-ethylenedioxythiophene), poly(3,4-propylenedioxythiophene), and poly(thieno[3,2-b]thiophene) films on glass slides and rough substrates, such as textiles and paper.

Réactif de Vapor Deposition de Films polymères conjugués sur substrats arbitraires

We demonstrate a method of conformally coating conjugated polymers on arbitrary substrates using a custom-designed, low-pressure reaction chamber. ...

Solution-Processed "Silver-Bismuth-Iodine" Ternary Thin Films for Lead-Free Photovoltaic Absorbers

Bismuth-based hybrid perovskites are regarded as promising photo-active semiconductors for environment-friendly and air-stable solar cell applications. However, poor surface morphologies and relatively high bandgap energies have limited their potential. Silver-bismuth-iodine (Ag-Bi-I) is a promising semiconductor for optoelectronic devices. Therefore, we demonstrate the fabrication of Ag-Bi-I ternary thin films using material solution processing. The resulting thin films exhibit controlled surface morphologies and optical bandgaps according to their thermal annealing temperatures. In addition, it has been reported that Ag-Bi-I ternary systems crystallize to AgBi2I7, Ag2BiI5, etc. according to the ratio of the precursor chemicals. The solution-processed AgBi2I7 thin films exhibit a cubic-phase crystal structure, dense, pinhole-free surface morphologies with grains ranging in size from 200 to 800 nm, and an indirect bandgap of 1.87 eV. The resultant AgBi2I7 thin films show good air stability and energy band diagrams, as well as surface morphologies and optical bandgaps suitable for lead-free and air-stable single-junction solar cells. Very recently, a solar cell with 4.3% power conversion efficiency was obtained by optimizing the Ag-Bi-I crystal compositions and solar cell device architectures.

Solution-Processed &quot;Silver-Bismuth-Iodine&quot; Ternary Thin Films for Lead-Free Photovoltaic Absorbers

Herein, we present detailed protocols for solution-processed silver-bismuth-iodine (Ag-Bi-I) ternary semiconductor thin films fabricated on TiO2-coated transparent electrodes and their potential application as air-stable and lead-free optoelectronic devices.

Solution-traité « Silver-Bismuth-iode » ternaire minces pour absorbeurs photovoltaïques sans plomb

Bismuth-based hybrid perovskites are regarded as promising photo-active semiconductors for environment-friendly and air-stable solar cell applications. ...