Esta labor fue apoyada con fondos provistos por la Oficina de Investigación Naval. J. Fontana reconoce el Consejo Nacional de Investigación para un miembro asociado postdoctoral.

1. Monocapas Ligando en nanopartículas autoensambladas Como un ejemplo ilustrativo de la técnica de auto-ensamblaje,, películas monocapa macroscópicas-alcano tiol cubiertas de nanoesfera oro se producen de la siguiente manera: <ol><li> Concentrado 15 nm nanoesferas de oro (disponibles comercialmente a una densidad número: 10 12 partículas / ml) a ~ 10 13 partículas / ml en agua. <ol><li> Coloque 15 ml de la suspensión de agua nanoesfera diluida en un filtro centrífugo ultra alta (100 K Límite nominal de peso molecular). </li><li> Centrifugar el filtro / vial a 4500 xg durante 2 min o hasta que sólo unos pocos ml permanecen en la cámara de filtro. </li></ol></li><li> Resuspender el nanoesferas en aproximadamente 1 ml de agua desionizada (DI) de agua tal que la concentración de nanopartículas es 10 13 partículas / ml. La suspensión es estable durante varias horas una vez resuspendidas en agua DI. <ol><li> Compruebe la densidad del número y confirme las nanopartículas haNo he agregado. Diluir la suspensión de nanopartículas se concentró por un factor de 1:10 de nuevo a la concentración original mediante la colocación de 0.150 ml de la suspensión en una cubeta (1 cm de longitud de trayectoria), y para este añadir 1,35 ml de agua DI. </li><li> Colocar la cubeta en un espectrómetro y medir el espectro de absorbancia de la suspensión y la suspensión original. Compara la posición del pico y la anchura a media altura para asegurar que no se ha producido la agregación. La magnitud de los picos de absorbancia para ambas muestras debe ser aproximadamente la misma, asegurando así la muestra concentrada es más denso en un factor de 10. </li></ol></li><li> En una cubeta de vidrio de 20 ml de borosilicato separada añadir 1 ml de tetrahidrofurano (THF). </li><li> Añadir los ligandos tiol-alcano (por ejemplo, 5 ml de 1,6-hexanoditiol y 5 ml de 1-dodecanotiol) al THF y se agita la solución para mezclar uniformemente. Suficiente ligando debe añadirse para cubrir al menos toda la superficie de las nanopartículas en suspensión. ExceSS ligando aumenta la velocidad y eficiencia de la reacción. </li><li> En una campana extractora, verter el contenido del vial que contiene las nanoesferas de oro en el vial de THF ligandos. </li><li> Enroscar lo antes posible en la tapa y agitar el vial vigorosamente durante 15 segundos. </li><li> Retire la tapa y ajustar el vial en la campana de humos, la Figura 1 (a). En función de los ligandos utilizados, los dominios de las películas de nanopartículas de oro se forman rápidamente en la interfase aire-líquido, la Figura 1 (c). Las películas empezarán entonces a traducir hasta los lados del vial, la Figura 1 (d). Casi todas las nanopartículas tienen un tope con tiol-ligando, retirado de la suspensión, y se transportan a los lados del vial dentro de 1 h, la Figura 1 (e). </li></ol> 2. Transferencia de las monocapas sobre sustratos extraíbles <ol><li> Para transferir las películas sobre vidrio extraíble y sustratos de obleas de silicio: cortar los sustratos en un área de 12,5 mm x 25,4 mm utilizando unapluma de trazado / rueda. <ol><li> Sustratos de vidrio: limpia utilizando un enjuague de acetona, seguido por un enjuague de alcohol isopropílico, y, finalmente, un enjuague de agua DI. Permita que los sustratos que se seque, pase a la sección 2.2. </li><li> Oblea de silicio Sustratos: en una campana extractora de preparar la solución Piranha (3 partes de ácido sulfúrico concentrado y 1 parte de 30% de peróxido de hidrógeno, PRECAUCIÓN: oxidante, corrosivo). Colocar 15 ml de ácido sulfúrico en un vial de vidrio de borosilicato de 20 ml. Para este complemento lentamente 5 ml de peróxido de hidrógeno al 30%. No tapar el vial. Tenga precaución; la mezcla es muy exotérmica. Véase la referencia para obtener más información de seguridad 19. </li><li> Sumerja cuidadosamente los sustratos de obleas de silicio en la solución Piranha durante 30 minutos, retirar, enjuagar con agua desionizada y secar con nitrógeno. </li><li> Como un paso opcional, el vial utilizado para el intercambio de ligandos de nanopartículas y de auto-ensamblaje puede ser salinizada para forzar todas las nanopartículas sobre el sustrato de vidrio o SIlicon oblea en lugar de las paredes de la ampolla de vidrio, de lo contrario pase a la sección 2.2. </li><li> Llene el frasco de vidrio con una solución de pirañas (PRECAUCIÓN: oxidante, corrosivo), consulte la sección 2.1.2. </li><li> Dejar que el vial en remojo durante 30 min. Después de 30 min enjuagar el frasco con agua DI. </li><li> Llenar vial con 1% v / v de hexametildisilazano en acetona y la tapa. </li><li> Deje que el frasco sellado en remojo durante 24 horas, luego enjuague con agua desionizada y secar con nitrógeno. </li></ol></li><li> Antes de la agitación (sección 1.6) insertar el sustrato en el vial. Tornillo en la tapa y agitar. </li><li> Después de sacudir quitar la tapa y, con unas pinzas, coloque el sustrato casi vertical contra la pared del vial. </li><li> Utilizar una pipeta para recubrir la mezcla de reacción sobre el sustrato. La reacción se detiene cuando todo el disolvente orgánico se haya evaporado todo o la nanopartícula se han eliminado de la suspensión. </li></ol> 3. Análisis Monocapa <ol><li> Estimar elembalaje de la eficiencia de las nanoesferas en la monocapa rápidamente mediante la observación de la transmisión y propiedades de reflexión de la película. Ilumine la monocapa sobre sustratos de vidrio por detrás con una fuente de luz blanca. Con una fuente de luz blanca, una película de color uniforme debe ser observado por alta densidad películas monocapa de nanopartículas en la transmisión y una reflexión de oro-como se observa en la reflexión, la Figura 2. </li><li> Utilice un espectrómetro (ver sección 1.2.2) para cuantificar el espectro de absorción macroscópica de las monocapas, Figura 4. Normalizar el espectro de absorción con un portaobjetos de vidrio limpio. Montar la película monocapa, sobre un sustrato de vidrio, en la trayectoria del haz del espectrómetro y recoger el espectro de absorción. Nota: El pico de absorbancia debe ser significativamente rojos-desplazado varios cientos de nanómetros, dependiendo del ligando utilizado. El factor de calidad del pico de absorbancia debería ser comparable al valor suspensión diluida, pero sólo ligeramente broadened (Figura 4). Si el pico de absorbancia es muy amplia o no bien definida luego las películas monocapa son probablemente de mala calidad, pase a la sección 3.3 para una mayor caracterización. </li><li> Examinar la organización nanoscópico de las nanoesferas mediante microscopía electrónica de barrido (SEM) de las monocapas transferidas sobre sustratos de obleas de silicio (véase la sección 2.1.2) como se muestra en la Figura 3. Si las películas son en vidrio sustratos conectan cinta conductora a una esquina de la película y lo molía en el pedestal SEM para impedir la carga y permitir que imágenes. </li></ol> 4. Técnica de Transferencia Eficiente de fase para orgánicos solubles nanopartículas <ol><li> Para utilizar la técnica como un medio eficaz para funcionalizar las nanopartículas con tiol-ligandos, se decanta la solución restante de la parte inferior del vial después de la reacción es completa, la sección 1.7, y secar el material en el vial en atmósfera de nitrógeno. </li><li> Añadir un disolvente orgánico (por ejemplo,cloroformo, tolueno) para volver a suspender las nanopartículas con transferencia de fase de partículas casi el 100% y la recuperación. </li><li> Repita la sección 1.2.1 para asegurar las nanopartículas no han agregado al volver a la suspensión en el disolvente orgánico. Si el pico de absorbancia es bordo, relativa a la suspensión original, someter a ultrasonidos la muestra durante 15 min para ayudar a redispersar las nanopartículas, la figura 4. </li></ol>

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Los autores no tienen nada que revelar.

Este protocolo describe una técnica única &quot;one-pot&quot; auto-ensamblaje para crear macroscópicas películas monocapa en nanopartículas ligando mediante transferencia de fase, la separación de fases y los gradientes de tensión superficial. La ventaja de esta técnica es que combina tres procesos de autoensamblaje en un proceso sencillo y de bajo costo; por forma rápida y eficiente eliminar la transferencia de las nanopartículas, el montaje de las partículas en monocapas en la interfase aire-líquido y el t...

El autoensamblaje de películas de nanopartículas macroscópicas ha atraído gran atención por sus propiedades únicas determinadas a partir de la geometría y la composición de los elementos 5 y puede conducir a la de una amplia gama de aplicaciones ópticas, electrónicas y químicas 6-14. Para este tipo de películas auto-ensamblan nanopartículas metálicas coronadas con ligandos deben ser embalados en alta densidad, monocapas. Sin embargo, varias cuestiones de montaje deben ser abordados para avanzar en el desarrollo de este tipo de materiales. En primer lugar, tensioactivo estabilizado nanopartículas metálicas son típicamente sintetizados por métodos de química húmeda en suspensiones diluidas 15. Para evitar la agregación y para controlar el espaciado entre partículas de las nanopartículas en las películas, las nanopartículas deben ser cubiertas con conchas de ligando. Después de que las nanopartículas han sido funcionalizado con ligandos de las nanopartículas típicamente permanecen en suspensiones relativamente diluidas. Una técnica es entonces NEEDED para auto-ensamblan las nanopartículas en, de alta densidad, películas monocapa macroscópicos 16, 17. Cheng et al. 18 fase transfiere nanorods oro usando poliestireno tiolado en una suspensión de agua-tetrahidrofurano. Los nanorods donde luego re-suspendió en cloroformo y una gota se colocó en una interfase aire-agua y se evapora lentamente, formando películas monocapa. Bigioni et al. 17 creado monocapas macroscópicas de dodecanotiol cubiertas nanoesferas de oro utilizando el exceso de ligando y evaporación del disolvente rápido, pero las nanoesferas necesita para ser transferido antes de la fase de auto-ensamblaje. Una vez que se forman las películas monocapa que típicamente necesitan ser transportados sobre un sustrato. Mayya et al. 3 confinada nanoesferas en una interfase agua-tolueno y los transferidos sobre sustratos en plantillas gratis con gradientes de tensión superficial. Del mismo modo, Johnson <em&gt; et al. 4 nanoesferas de plata en suspensión en exceso de ligando y luego traducen las nanopartículas hasta las paredes del vial utilizando gradientes de tensión superficial a partir de dos líquidos inmiscibles. Aunque existen técnicas de montaje para abordar cada uno de estos temas se necesita la necesidad de técnicas más eficientes para ayudar en el desarrollo de la producción de película de nanopartículas a gran escala. Aquí se demuestra una técnica sencilla y robusta que combina los tres problemas de auto-ensamblaje descritos anteriormente en a una sola técnica de &quot;un solo recipiente &#39;, que se muestra en la Figura 1. Un disolvente orgánico miscible en agua (por ejemplo, tetrahidrofurano, sulfóxido de dimeythl), se utiliza para primero de forma rápida y eficiente funcionalizar tiol-ligandos (por ejemplo,-alcano tiol, tiol-eno, tiol-fenol) en las nanopartículas (por ejemplo, nanoesferas de oro, nanovarillas, etc.) La mezcla se lleva a la auto-montaje de las nanopartículas en macroscópico, de alta densidad, Monolayer películas en la interfase aire-líquido utilizando la separación de fases. Finalmente, las películas monocapa de nanopartículas forman sobre sustratos-libre de la plantilla utilizando gradientes de tensión superficial de la mezcla de agua / disolvente orgánico, la Figura 2 y la Figura 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

Este protocolo describe una técnica de auto-ensamblaje para crear películas monocapa macroscópicos formados por nanopartículas ligando recubierto 1, 2. La técnica sencilla, robusta y escalable funcionaliza eficiente nanopartículas metálicas con tiol-ligandos en una mezcla de agua / disolvente orgánico miscible con lo que permite un rápido injerto de grupos tiol sobre la superficie de nanopartículas de oro. Los ligandos hidrófobos sobre las nanopartículas luego rápidamente fase se separan las nanopartículas de la suspensión de base acuosa y se limitan a la interfase aire-líquido. Esto impulsa las nanopartículas ligando-capsulado para formar dominios monocapa en la interfase aire-líquido. El uso de disolventes orgánicos miscibles en agua es importante, ya que permite el transporte de las nanopartículas de la interfaz sobre sustratos-libre de la plantilla. El flujo está mediada por una tensión gradiente de la superficie 3, 4 y crea macroscópica, de alta densidad, nanop monocapapelículas artículo ligando. Esta técnica de auto-ensamblaje puede ser generalizado para incluir el uso de partículas de diferentes composiciones, tamaño y forma y puede dar lugar a un método de montaje eficiente de producir películas de bajo costo, macroscópicas, de alta densidad, de nanopartículas monocapa para aplicaciones muy extendidas .

La Figura 1 (a) muestra una suspensión de nanoesferas de oro, ligandos-alcano tiol, tetrahidrofurano y agua en un vial de vidrio inmediatamente después de la mezcla. Un esquemática de las tres etapas principales de autoensamblaje, de transferencia de fase, separación de fases, y la superficie de gradiente de tensión de transporte de película mediada se muestra en la Figura 1 (b) como una vista ampliada en la interfase aire-líquido cerca de la pared del vial. <p class="jove_co...

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

Una técnica simple, robusta y escalable para funcionalizar y auto-ensamblan películas monocapa en nanopartículas ligando macroscópicas en soportes plantilla gratuita se describe en este protocolo.

Una técnica para funcionalizar y auto-ensamblan macroscópicas nanopartículas ligando monocapa Films en soportes de plantillas gratis

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

a-technique-to-functionalize-self-assemble-macroscopic-nanoparticle

Research

JoVE Journal

Chemistry

10.8K vistas.  Naval Research Laboratory.  Una técnica simple, robusta y escalable para funcionalizar y auto-ensamblan películas monocapa en nanopartículas ligando macroscópicas en soportes plantilla gratuita se describe en este protocolo. 

Video: 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.

Unión covalente de BMP-2 en las superficies utilizando una monocapa enfoque de auto-ensamblada

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 ...

Investigación

Química

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.

Hacia Biomimicking Madera: Fabricada en monobloque películas de nanocellulose, lignina, y una Policatión sintético

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.

Plantillas Atómicamente definidos para crecimiento epitaxial de óxido complejo Películas Delgadas

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.

La fabricación de superficies de gran autoportante ultrafinos Polymer Films

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.

Preparación de Mica y Silicon Sustratos para el Análisis de Origami ADN y Experimentación

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.

Enfriamiento Puntúa Medidas Elipsometría Dependientes para determinar la dinámica de Thin Films vidriosos

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.

Ensayos de desacetilación para desentrañar la interacción entre las sirtuinas (SIRT2) y proteína-sustratos específicos

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.

La electroforesis capilar para supervisar Péptido injerto sobre quitosano películas en tiempo real

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.

Deposición de Vapor reactivo de polímero conjugado películas sobre sustratos de arbitrarias

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.

Solución procesada "Plata, bismuto, yodo" ternario películas delgadas para absorbedores fotovoltaicas sin plomo

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