Este trabajo es apoyado por la oficina de investigación del ejército de Estados Unidos bajo la subvención W911NF-15-1-0414.

1. preparación de la célula Knudsen caseros
<ol><li>
Preparar los componentes para la célula Knudsen
	<ol>
<li>Compra un CF brida base paso de poder (2,75" CF, 4 pernos de acero inoxidable). Perfore dos agujeros roscados a través del paso, en los puntos de cruce entre un diámetro 1,30" línea y su circunferencia.</li>
		<li>Preparar un tubo de vidrio (0,315" diámetro (OD), 2,50" longitud exterior).</li>
		<li>Compra de láminas delgadas de cobre (99,9%) con espesor de 0.005". Cortar una hoja a las dimensiones de L 7.5" x 5.0" W con un par de tijeras y rizo a un hueco columniform escudo con un diámetro de 1,45" con la mano (Figura 1a).</li>
		<li>Preparar el termopar tipo K (Cromel/Cromel) con un diámetro de 0.005" cortando una longitud de 3" para los cables el Cromel y Cromel. Pelar las capas de aislante alrededor de 0.5" de largo en ambos extremos de ambos cables.</li>
		<li>Corte un 0,01" diámetro alambre de tungsteno (99.95%) a una longitud de aproximadamente 60". Enróllela en forma de resorte con un diámetro de 0,315" envolviéndola firmemente alrededor de una barra de un diámetro comparable del tubo de vidrio.</li>
		<li>Comprar una pieza de cerámica. Preparar una pieza cuboide adecuada con un agujero en el medio que se adapta a la dimensión del cristal (5 en Figura 1b).</li>
		<li>Cortar 2 barras de diámetro estándar acero roscado 0,10" un 7" por las bandas y corte con una máquina de torno.</li>
		<li>Cortar un alambre de cobre de diámetro 0,01" suave, un aproximado de 30" usando una tijera.</li>
		<li>Preparar 4 barras de cobre hueco con un diámetro de OD de 0,094" cortando tres barras a un 2" de largo y una barra a una longitud de 4" con un corte lateral.</li>
	</ol>
</li>
	<li>
Montar estas piezas en la célula Knudsen
	<ol>
<li>Limpie todos los componentes mencionados en el paso 1.1 utilizando ultrasonidos limpieza a 42 kHz en acetona durante 30 minutos.</li>
		<li>Monte 2 barras roscadas acero estándar en los orificios de la brida CF del paso de energía. Nota: Los orificios están roscados (7 en Figura 1b).</li>
		<li>Monte la parte inferior de la mitad de las 4 barras de cobre hueco en la parte superior de los 4 pines del paso de energía CF brida insertando el pasador en las barras de cobre hueco y fijación por un cortador lateral (6 en la Figura 1b).</li>
		<li>Monte la pieza de cerámica en la posición de 2,5" alto de la parte inferior de las varillas roscadas con alambre de cobre suave. Nota: Esta pieza apoyará el tubo de vidrio en el siguiente paso (5 en Figura 1b).</li>
		<li>Deslice el tubo de vidrio en el resorte de espiral de tungsteno. Apriete la parte inferior del tubo de vidrio en el orificio de la pieza cerámica. Use cable de cobre suave para sostener el extremo superior del tubo de vidrio en el extremo superior de las varillas roscadas (3 y 4 en Figura 1b).</li>
		<li>Sujete el extremo superior del resorte en la barra de cobre largo, definida como A. Agarre el extremo inferior del resorte en una de las barras de cobre más cortas, definidas como B (A y B en la Figura 1b).</li>
		<li>Tuerza un extremo pelado del cromel y Cromel cables juntos (2 en Figura 1b).</li>
		<li>Coloque el extremo conjunto trenzado por lo que toca muy de cerca la parte inferior exterior del tubo de vidrio. Inmovilizarlo con la ayuda de la pieza cerámica.</li>
		<li>Agarre el otro extremo pelado de la Cromel de alambre en uno las izquierda 2 menor de barras de cobre, definidas como C. Agarre el otro extremo pelado del cable Cromel en la barra de cobre corto izquierdo, definido como D (C y D en Figura 1b).</li>
		<li>Poner el escudo columniform hueco cobre rizado en el paso de energía de CF con bridas (Figura 1a).</li>
	</ol>
</li>
</ol>2. prepare la fuente de60 C en la celda de caseros Knudsen
<ol><li>Carga la fuente de60 C en la célula Knudsen casera.<ol>
<li>Cargar aproximadamente 50 mg de polvo de60 C (99,5% de pureza) en el tubo de cristal de la casera célula Knudsen. Nota: La precisión más allá de 1 mg de la masa del polvo es innecesario.</li>
		<li>Montar la célula Knudsen en una rama de la cerradura de la carga.</li>
	</ol>
</li>
	<li>El bloqueo de carga de la bomba.<ol>
<li>Encienda la bomba para el bloqueo de carga. Primero encienda la válvula de agua para la refrigeración de la bomba de turbo, luego encienda el ventilador para enfriar la bomba mecánica. Luego encienda la bomba mecánica y por último encienda la bomba de turbo.</li>
		<li>Compruebe la presión en el bloqueo de carga y esperar aproximadamente 10 horas. Nota: La presión a la salida de la bomba turbo debe ser 6.0 x 10-2 mbar.</li>
		<li>Encienda el medidor de iones montado en la cerradura de la carga a una presión más baja (típicamente por debajo de 10-6 mbar).</li>
		<li>Controlar la presión en el bloqueo de carga: la presión debe ser en el rango de 10-8 mbar después de 10 h de bombeo.</li>
	</ol>
</li>
	<li>Recueza la fuente de60 C en la célula Knudsen casera.<ol>
<li>Recueza la fuente de60 C en la célula Knudsen casera poco a poco (1,5 ° C/min) a 250 ° C por 2 h para la desgasificación conectando un poder suministrar en dos alfileres del paso de energía de CF con bridas, que están conectados a la fuente de tungsteno rizado.</li>
		<li>Aumentar la temperatura de recocido a 300 ° C, que es superior a la temperatura de deposición (270 ° C).</li>
		<li>Cocer a 300 º C durante 0,5 h para mayor desgasificación.</li>
		<li>Disminuir la temperatura a 270 ° C para la deposición.</li>
	</ol>
</li>
</ol>3. prepare el grafeno atómicamente limpia en la cámara UHV
<ol><li>Transferir el grafeno (en hoja de cobre) desde el carrusel de almacenamiento de la muestra a la placa de recocido en la cámara de ultra alto vacío preparación del sistema STM (un lugar especial para la preparación y recocido una muestra en ultra alto vacío).</li>
	<li>Recueza el sustrato de grafeno a una presión base de baja 10-10 mbar dentro de la cámara de preparación poco a poco aumentando la temperatura a 400 ° C.</li>
	<li>Esperar 12 h eliminar las impurezas residuales en la superficie del grafeno.</li>
	<li>Disminuir la temperatura de recocido para sustrato de grafeno gradualmente a la temperatura ambiente.</li>
</ol>4. depósito C 60 sobre sustrato de grafeno mediante la célula Knudsen caseros en bloqueo de carga
<ol><li>Transferencia del sustrato de grafeno a la cerradura de la carga.<ol>
<li>Coloque la placa en la cámara de preparación en la posición de transferencia. Transferir el grafeno atómicamente limpia a la cerradura de la carga para deposición C60, después de tener el C60 fuente preparado y grafeno atómicamente limpia.</li>
		<li>Abra la válvula entre el bloqueo de carga y el compartimiento de la preparación.</li>
		<li>Transferencia del sustrato de grafeno de la placa en la cámara de preparación para el bloqueo de carga con la herramienta de rutinas de carga.</li>
		<li>Coloque el sustrato grafeno abajo (C60 viene de la fuente abajo).</li>
	</ol>
</li>
	<li>Depósito C60 sobre el substrato de grafeno. Nota: C60 moléculas transferencia de la célula Knudsen casera al sustrato de grafeno a 270 ° C.<ol>
<li>Espere 1 minuto con una velocidad de deposición de 0,9 monocapa/min.</li>
		<li>Transferir la muestra de /graphene de60C a la sala de preparación.</li>
	</ol>
</li>
</ol>5. prepare la C 60 /Graphene muestra que será medida en la cámara principal de STM
<ol><li>Recueza la muestra de /graphene de60C a 150 ° C con una tasa de 3,1 ° C/min durante 2 h en la sala de preparación de vacío ultra alto.</li>
	<li>Analizar la muestra de /graphene de60C con STM en la cámara principal del STM.</li>
	<li>Recueza la muestra de /graphene de60C a 210 ° C con una tasa de 3,1 ° C/min durante 2 h.</li>
	<li>Analizar la muestra de /graphene de60C con STM.</li>
</ol>

<ol>
	<li>Gutzler, R., Heckl, W. M., Lackinger, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Combination+of+a+Knudsen+effusion+cell+with+a+quartz+crystal+microbalance:+In+situ+measurement+of+molecular+evaporation+rates+with+a+fully+functional+deposition+source.">Combination of a Knudsen effusion cell with a quartz crystal microbalance: In situ measurement of molecular evaporation rates with a fully functional deposition source.</a> Review of Scientific Instruments. 81, 015108 (2010).</li><li>de Barros, A. L. F., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+simple+experimental+arrangement+for+measuring+the+vapour+pressures+and+sublimation+enthalpies+by+the+Knudsen+effusion+method:+Application+to+DNA+and+RNA+bases.">A simple experimental arrangement for measuring the vapour pressures and sublimation enthalpies by the Knudsen effusion method: Application to DNA and RNA bases.</a> Nuclear Instruments &amp; Methods in Physics Research Section a-Accelerators Spectrometers Detectors and Associated Equipment. 560, (2006).</li><li>Shukla, A. K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Versatile+UHV+compatible+Knudsen+type+effusion+cell.">Versatile UHV compatible Knudsen type effusion cell.</a> Review of Scientific Instruments. 75, 4467 (2004).</li><li>Cho, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Structural+and+Electronic+Decoupling+of+C60+from+Epitaxial+Graphene+on+SiC.">Structural and Electronic Decoupling of C60 from Epitaxial Graphene on SiC.</a> Nano Letters. 12, 3018 (2012).</li><li>Jung, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Atomically+resolved+orientational+ordering+of+C60+molecules+on+epitaxial+graphene+on+Cu(111).">Atomically resolved orientational ordering of C60 molecules on epitaxial graphene on Cu(111).</a> Nanoscale. 6 (111), 11835 (2014).</li><li>Li, G., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Self-assembly+of+C60+monolayer+on+epitaxially+grown,+nanostructured+graphene+on+Ru(0001)+surface.">Self-assembly of C60 monolayer on epitaxially grown, nanostructured graphene on Ru(0001) surface.</a> Applied Physics Letters. 100 (0001), 013304 (2012).</li><li>Lu, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Using+the+Graphene+Moire+Pattern+for+the+Trapping+of+C60+and+Homoepitaxy+of+Graphene.">Using the Graphene Moire Pattern for the Trapping of C60 and Homoepitaxy of Graphene.</a> Acs Nano. 6, 944 (2012).</li><li>Zhou, H. T., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Direct+imaging+of+intrinsic+molecular+orbitals+using+two-dimensional,+epitaxially-grown,+nanostructured+graphene+for+study+of+single+molecule+and+interactions.">Direct imaging of intrinsic molecular orbitals using two-dimensional, epitaxially-grown, nanostructured graphene for study of single molecule and interactions.</a> Applied Physics Letters. 99, 153101 (2011).</li><li>Belaish, I., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Spin+Cast+Thin-Films+of+Fullerenes+and+Fluorinated+Fullerenes+-+Preparation+and+Characterization+by+X-Ray+Reflectivity+and+Surface+Diffuse-X-Ray+Scattering.">Spin Cast Thin-Films of Fullerenes and Fluorinated Fullerenes - Preparation and Characterization by X-Ray Reflectivity and Surface Diffuse-X-Ray Scattering.</a> Journal of Applied Physics. 71, 5248 (1992).</li><li>Bezmel'nitsyn, V. N., Eletskii, A. V., Okun', M. V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fullerenes+in+solutions.">Fullerenes in solutions.</a> Uspekhi Fizicheskikh Nauk. 168, 1195 (1998).</li><li>Ma, D. N., Sandoval, S., Muralidharan, K., Raghavan, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effect+of+surface+preparation+of+copper+on+spin-coating+driven+self-assembly+of+fullerene+molecules.">Effect of surface preparation of copper on spin-coating driven self-assembly of fullerene molecules.</a> Microelectronic Engineering. 170, 8 (2017).</li><li>Chen, C. H., Zheng, H. S., Mills, A., Heflin, J. R., Tao, C. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Temperature+Evolution+of+Quasi-one-dimensional+C60+Nanostructures+on+Rippled+Graphene.">Temperature Evolution of Quasi-one-dimensional C60 Nanostructures on Rippled Graphene.</a> Scientific Reports. 5, 14336 (2015).</li></ol>

No tenemos nada que revelar.

Las técnicas descritas en este protocolo están diseñadas para deposición térmica de materiales orgánicos y otros materiales de alta presión de vapor. Estas técnicas pueden integrarse con sistemas de vacío ultra altos que tienen áreas de preparación de muestra capaces de soportar la evaporación molecular así como térmico de recocido. Para este experimento específico se pretende depositar moléculas de60 C en sustrato de grafeno y el estudio del autoensamblaje de C60 y el efecto térmic...

Este protocolo explica cómo depositar y manipular moléculas de60 C en grafeno que 1D y cuasi - D 1 C60 cadena estructuras pueden realizarse. Las técnicas en este experimento fueron desarrolladas para hacer frente a la necesidad de guiar adsorbatos en configuraciones deseables sin tener que depender de la manipulación manual, lo cual es lenta y puede requerir gran esfuerzo. Los procedimientos aquí descritos se basan en el uso de un sistema de vacío alta con un área de preparación de muestra capaz de soportar la deposición molecular y recocido térmico de las muestras. STM se utiliza para caracterizar las muestras, pero pueden aplicarse otras técnicas de resolución molecular.
La evaporación térmica de las moléculas dentro de una célula Knudsen es una manera eficiente y limpia para preparar láminas delgadas. En este protocolo, se utiliza una célula Knudsen se evapore C60 moléculas sobre un sustrato de grafeno. Este evaporador de célula Knudsen consiste principalmente en un tubo de cuarzo, un filamento de calefacción, cables de termopar y pasantes1,2,3. El tubo de cuarzo se utiliza para dar cabida a las moléculas, los calores de filamento de tungsteno las moléculas en el cuarzo del tubo a través de la aplicación actual, y los alambres del termopar se utilizan para medir la temperatura. En los experimentos, la tasa de deposición es controlada por ajuste la fuente de temperatura en la célula Knudsen. Los cables de termopar se unen a la pared exterior del tubo de cuarzo y por lo tanto suelen medir una temperatura de la pared exterior que es ligeramente diferente de la temperatura interior de la célula donde se encuentra el origen molecular. Para obtener la temperatura exacta en el tubo de cuarzo, se realizó la calibración con dos configuraciones de termopar para medir temperatura interior y exterior del tubo y registran la diferencia de temperatura. De esta manera, más precisamente podemos controlar la temperatura de la fuente durante los experimentos moleculares de la evaporación utilizando cables termopar exterior del tubo de cuarzo. Porque una pequeña cantidad de las moléculas sublimadas estará en una fase gaseosa a una presión más baja, cuando las moléculas se evaporan, hay generalmente un cambio de la presión asociada. Por lo tanto, hacemos un seguimiento el cambio de la presión en el bloqueo de carga cuidadosamente.
Este evaporador puede utilizarse para depositar diversas fuentes de molécula como C60, C70, cloruro de subphthalocyanine de boro, Ga, Al, Hg4,5,6,7,8. En comparación con otras técnicas de preparación de película fina, por ejemplo, spin casting9,10,11, la evaporación térmica de alto vacío es mucho más limpio y versátil puesto que no hay ningún solvente para la deposición. Además, el proceso de desgasificación antes de la deposición mejora la pureza de la fuente, eliminar las posibles impurezas.

<table>
	<tbody>
		<tr>
			<td>CF Flanged power feedthrough</td>
			<td>Kurt J. Lesker</td>
			<td>EFT0042033</td>
			<td></td>
		</tr>
		<tr>
			<td>Copper sheets</td>
			<td>Alfa Aesar</td>
			<td>7440-50-8</td>
			<td></td>
		</tr>
		<tr>
			<td>Thermocouple chromel/alumel wires</td>
			<td>Omega Engineering</td>
			<td>ST032034/ST080042</td>
			<td></td>
		</tr>
		<tr>
			<td>Tungsten wires</td>
			<td>Alfa Aesar</td>
			<td>7440-33-7</td>
			<td></td>
		</tr>
		<tr>
			<td>Stainless steel rods</td>
			<td>McMaster-Carr</td>
			<td>95412A868</td>
			<td></td>
		</tr>
		<tr>
			<td>Copper wires</td>
			<td>McMaster-Carr</td>
			<td>8873K28</td>
			<td></td>
		</tr>
		<tr>
			<td>Hollow copper rods</td>
			<td>McMaster-Carr</td>
			<td>7190K52</td>
			<td></td>
		</tr>
		<tr>
			<td>C60</td>
			<td>MER Corporation</td>
			<td>MR6LP</td>
			<td></td>
		</tr>
	</tbody>
</table>

preparation and characterization of c60/graphene hybrid nanostructures

Deposición física termal en un alto ambiente de vacío es un método limpio y controlable para la fabricación de nuevas nanoestructuras moleculares en grafeno. Se presentan métodos para depositar y manipular pasivo C60 moléculas de grafeno ondulado que avanzan en la búsqueda de aplicaciones realizando D C 1 y60estructuras híbridas de /graphene. Las técnicas aplicadas en esta exposición están orientadas a sistemas de vacío alta con zonas de preparación capaces de soportar la deposición molecular así como recocido térmico de las muestras. Nos centramos en la deposición de60 C a baja presión usando una célula Knudsen casera conectada a un sistema de microscopia (STM) túnel de exploración. El número de moléculas depositadas se regula mediante el control de la temperatura de la célula de Knudsen y el tiempo de deposición. Unidimensional (1D) C60 cadena las estructuras con un ancho de dos a tres moléculas pueden prepararse mediante la adaptación de las condiciones experimentales. La movilidad superficial de las moléculas de60 C aumenta con la temperatura de recocido que les permite moverse dentro el potencial periódico del grafeno ondulado. Mediante este mecanismo, es posible controlar la transición de 1 D C60 estructuras de cadena a una estructura de banda hexagonal estrecha llena cuasi - 1D.

Tras la evaporación, es templado el grafeno con el recién depositado C60 a 150 ° C por 2 h. La imagen STM a gran escala en la Figura 2a muestra una estructura característica cuasi - 1 D C60 cadena encontró después de este proceso inicial de recocido. Una inspección más cercana en la figura 2b muestra información detallada de esta estructura de 1 D, en el cual cada brillante protuberancia esférica r...

Watch this Scientific Journal Video about Preparation and Characterization of C60/Graphene Hybrid Nanostructures at JoVE.com

Preparation and Characterization of C60/Graphene Hybrid Nanostructures

Preparación y caracterización de nanoestructuras de C60/Graphene híbrido

Aquí presentamos un protocolo para la fabricación de nanoestructuras de C60/graphene híbrido por evaporación térmica física. Particularmente, la manipulación adecuada de deposición y recocidas condiciones permiten el control sobre la creación de 1D y cuasi 1 C60 estructuras en grafeno ondulado.

Physical thermal deposition in a high vacuum environment is a clean and controllable method for fabricating novel molecular nanostructures on graphene. We ...

preparation-and-characterization-of-c60graphene-hybrid-nanostructures

Research

JoVE Journal

Chemistry

Preparation and Characterization of C60/Graphene Hybrid Nanostructures

9.4K vistas.  Virginia Tech. Aquí presentamos un protocolo para la fabricación de nanoestructuras de C60/graphene híbrido por evaporación térmica física. Particularmente, la manipulación adecuada de deposición y recocidas condiciones permiten el control sobre la creación de 1D y cuasi 1 C60 estructuras en grafeno ondulado.

Video: Preparation and Characterization of C60/Graphene Hybrid Nanostructures

Gyroid Nickel Nanostructures from Diblock Copolymer Supramolecules

Nanoporous metal foams possess a unique combination of properties - they are catalytically active, thermally and electrically conductive, and furthermore, have high porosity, high surface-to-volume and strength-to-weight ratio. Unfortunately, common approaches for preparation of metallic nanostructures render materials with highly disordered architecture, which might have an adverse effect on their mechanical properties. Block copolymers have the ability to self-assemble into ordered nanostructures and can be applied as templates for the preparation of well-ordered metal nanofoams. Here we describe the application of a block copolymer-based supramolecular complex - polystyrene-block-poly(4-vinylpyridine)(pentadecylphenol) PS-b-P4VP(PDP) - as a precursor for well-ordered nickel nanofoam. The supramolecular complexes exhibit a phase behavior similar to conventional block copolymers and can self-assemble into the bicontinuous gyroid morphology with two PS networks placed in a P4VP(PDP) matrix. PDP can be dissolved in ethanol leading to the formation of a porous structure that can be backfilled with metal. Using electroless plating technique, nickel can be inserted into the template&#39;s channels. Finally, the remaining polymer can be removed via pyrolysis from the polymer/inorganic nanohybrid resulting in nanoporous nickel foam with inverse gyroid morphology.

This article describes the preparation of well-ordered nickel nanofoams via electroless metal deposition onto nanoporous templates obtained from self-assembled diblock copolymer based supramolecules.

Gyroid Níquel Nanoestructuras de copolímero de dibloques supramoléculas

Nanoporous metal foams possess a unique combination of properties - they are catalytically active, thermally and electrically conductive, and furthermore, ...

Investigación

Química

Split-and-pool Synthesis and Characterization of Peptide Tertiary Amide Library

Peptidomimetics are great sources of protein ligands. The oligomeric nature of these compounds enables us to access large synthetic libraries on solid phase by using combinatorial chemistry. One of the most well studied classes of peptidomimetics is peptoids. Peptoids are easy to synthesize and have been shown to be proteolysis-resistant and cell-permeable. Over the past decade, many useful protein ligands have been identified through screening of peptoid libraries. However, most of the ligands identified from peptoid libraries do not display high affinity, with rare exceptions. This may be due, in part, to the lack of chiral centers and conformational constraints in peptoid molecules. Recently, we described a new synthetic route to access peptide tertiary amides (PTAs). PTAs are a superfamily of peptidomimetics that include but are not limited to peptides, peptoids and N-methylated peptides. With side chains on both &#945;-carbon and main chain nitrogen atoms, the conformation of these molecules are greatly constrained by sterical hindrance and allylic 1,3 strain. (Figure 1) Our study suggests that these PTA molecules are highly structured in solution and can be used to identify protein ligands. We believe that these molecules can be a future source of high-affinity protein ligands. Here we describe the synthetic method combining the power of both split-and-pool and sub-monomer strategies to synthesize a sample one-bead one-compound (OBOC) library of PTAs.

Peptide tertiary amides (PTAs) are a superfamily of peptidomimetics that include but are not limited to peptides, peptoids and N-methylated peptides. Here we describe a synthetic method which combines&#160;both split-and-pool and sub-monomer strategies to synthesize a one-bead one-compound library of PTAs.

Síntesis Split-y-piscina y caracterización del péptido Terciario Amida Biblioteca

Peptidomimetics are great sources of protein ligands. The oligomeric nature of these compounds enables us to access large synthetic libraries on solid ...

Synthesis and Characterization of Functionalized Metal-organic Frameworks

Metal-organic frameworks have attracted extraordinary amounts of research attention, as they are attractive candidates for numerous industrial and technological applications. Their signature property is their ultrahigh porosity, which however imparts a series of challenges when it comes to both constructing them and working with them. Securing desired MOF chemical and physical functionality by linker/node assembly into a highly porous framework of choice can pose difficulties, as less porous and more thermodynamically stable congeners (e.g., other crystalline polymorphs, catenated analogues) are often preferentially obtained by conventional synthesis methods. Once the desired product is obtained, its characterization often requires specialized techniques that address complications potentially arising from, for example, guest-molecule loss or preferential orientation of microcrystallites. Finally, accessing the large voids inside the MOFs for use in applications that involve gases can be problematic, as frameworks may be subject to collapse during removal of solvent molecules (remnants of solvothermal synthesis). In this paper, we describe synthesis and characterization methods routinely utilized in our lab either to solve or circumvent these issues. The methods include solvent-assisted linker exchange, powder X-ray diffraction in capillaries, and materials activation (cavity evacuation) by supercritical CO2 drying. Finally, we provide a protocol for determining a suitable pressure region for applying the Brunauer-Emmett-Teller analysis to nitrogen isotherms, so as to estimate surface area of MOFs with good accuracy.

Synthesis, activation, and characterization of intentionally designed metal-organic framework materials is challenging, especially when building blocks are incompatible or unwanted polymorphs are thermodynamically favored over desired forms. We describe how applications of solvent-assisted linker exchange, powder X-ray diffraction in capillaries and activation via supercritical CO2 drying, can address some of these challenges.

Marcos de síntesis y caracterización de funcionalizado metal-orgánico

Metal-organic frameworks have attracted extraordinary amounts of research attention, as they are attractive candidates for numerous industrial and ...

Preparation and Characterization of SDF-1&#945;-Chitosan-Dextran Sulfate Nanoparticles

Chitosan (CS) and dextran sulfate (DS) are charged polysaccharides (glycans), which form polyelectrolyte complex-based nanoparticles when mixed under appropriate conditions. The glycan nanoparticles are useful carriers for protein factors, which facilitate the in vivo delivery of the proteins and sustain their retention in the targeted tissue. The glycan polyelectrolyte complexes are also ideal for protein delivery, as the incorporation is carried out in aqueous solution, which reduces the likelihood of inactivation of the proteins. Proteins with a heparin-binding site adhere to dextran sulfate readily, and are, in turn, stabilized by the binding. These particles are also less inflammatory and toxic when delivered in vivo. In the protocol described below, SDF-1&#945; (Stromal cell-derived factor-1&#945;), a stem cell homing factor, is first mixed and incubated with dextran sulfate. Chitosan is added to the mixture to form polyelectrolyte complexes, followed by zinc sulfate to stabilize the complexes with zinc bridges. The resultant SDF-1&#945;-DS-CS particles are measured for size (diameter) and surface charge (zeta potential). The amount of the incorporated SDF-1&#945; is determined, followed by measurements of its in vitro release rate and its chemotactic activity in a particle-bound form.

The objective of this protocol is to incorporate SDF-1&#945;, a stem cell homing factor, into dextran sulfate-chitosan nanoparticles. The resultant particles are measured for their size and zeta potential, as well as the content, activity, and in vitro release rate of SDF-1&#945; from the nanoparticles.

Preparación y caracterización de SDF-1α-quitosano-sulfato de dextrano Nanopartículas

Chitosan (CS) and dextran sulfate (DS) are charged polysaccharides (glycans), which form polyelectrolyte complex-based nanoparticles when mixed under ...

Preparation and Characterization of Individual and Multi-drug Loaded Physically Entrapped Polymeric Micelles

Amphiphilic block copolymers like polyethyleneglycol-block-polylactic acid (PEG-b-PLA) can self-assemble into micelles above their critical micellar concentration forming hydrophobic cores surrounded by hydrophilic shells in aqueous environments. The core of these micelles can be utilized to load hydrophobic, poorly water soluble drugs like docetaxel (DTX) and everolimus (EVR). Systematic characterization of the micelle structure and drug loading capabilities are important before in vitro and in vivo studies can be conducted. The goal of the protocol described herein is to provide the necessary characterization steps to achieve standardized micellar products. DTX and EVR have intrinsic solubilities of 1.9 and 9.6 &#181;g/ml respectively Preparation of these micelles can be achieved through solvent casting which increases the aqueous solubility of DTX and EVR to 1.86 and 1.85 mg/ml, respectively. Drug stability in micelles evaluated at room temperature over 48 hr indicates that 97% or more of the drugs are retained in solution. Micelle size was assessed using dynamic light scattering and indicated that the size of these micelles was below 50 nm and depended on the molecular weight of the polymer. Drug release from the micelles was assessed using dialysis under sink conditions at pH 7.4 at 37 oC over 48 hr. Curve fitting results indicate that drug release is driven by a first order process indicating that it is diffusion driven.

The goal of this protocol is to describe the preparation and characterization of physically entrapped, poorly water soluble drugs in micellar drug delivery systems composed of amphiphilic block copolymers.

Preparación y Caracterización de Individual y Multi-fármaco cargado físicamente atrapado poliméricos micelas

Amphiphilic block copolymers like polyethyleneglycol-block-polylactic acid (PEG-b-PLA) can self-assemble into micelles above their critical micellar ...

Synthesis, Characterization, and Functionalization of Hybrid Au/CdS and Au/ZnS Core/Shell Nanoparticles

Plasmonic nanoparticles are an attractive material for light harvesting applications due to their easily modified surface, high surface area and large extinction coefficients which can be tuned across the visible spectrum. Research into the plasmonic enhancement of optical transitions has become popular, due to the possibility of altering and in some cases improving photo-absorption or emission properties of nearby chromophores such as molecular dyes or quantum dots. The electric field of the plasmon can couple with the excitation dipole of a chromophore, perturbing the electronic states involved in the transition and leading to increased absorption and emission rates. These enhancements can also be negated at close distances by energy transfer mechanism, making the spatial arrangement of the two species critical. Ultimately, enhancement of light harvesting efficiency in plasmonic solar cells could lead to thinner and, therefore, lower cost devices. The development of hybrid core/shell particles could offer a solution to this issue. The addition of a dielectric spacer between a gold nanoparticles and a chromophore is the proposed method to control the exciton plasmon coupling strength and thereby balance losses with the plasmonic gains. A detailed procedure for the coating of gold nanoparticles with CdS and ZnS semiconductor shells is presented. The nanoparticles show high uniformity with size control in both the core gold particles and shell species allowing for a more accurate investigation into the plasmonic enhancement of external chromophores.

The synthesis of uniform gold nanoparticles coated with semiconductor shells of CdS or ZnS is performed. The semiconductor coating is conducted by first depositing a silver sulfide shell and exchanging the silver cations for zinc or cadmium cations.

Síntesis, caracterización y funcionalización de híbridos Au / CdS y Au / ZnS Core / Shell nanopartículas

Plasmonic nanoparticles are an attractive material for light harvesting applications due to their easily modified surface, high surface area and large ...

Synthesis and Characterization of Supramolecular Colloids

Control over colloidal assembly is of utmost importance for the development of functional colloidal materials with tailored structural and mechanical properties for applications in photonics, drug delivery and coating technology. Here we present a new family of colloidal building blocks, coined supramolecular colloids, whose self-assembly is controlled through surface-functionalization with a benzene-1,3,5-tricarboxamide (BTA) derived supramolecular moiety. Such BTAs interact via directional, strong, yet reversible hydrogen-bonds with other identical BTAs. Herein, a protocol is presented that describes how to couple these BTAs to colloids and how to quantify the number of coupling sites, which determines the multivalency of the supramolecular colloids. Light scattering measurements show that the refractive index of the colloids is almost matched with that of the solvent, which strongly reduces the van der Waals forces between the colloids. Before photo-activation, the colloids remain well dispersed, as the BTAs are equipped with a photo-labile group that blocks the formation of hydrogen-bonds. Controlled deprotection with UV-light activates the short-range hydrogen-bonds between the BTAs, which triggers the colloidal self-assembly. The evolution from the dispersed state to the clustered state is monitored by confocal microscopy. These results are further quantified by image analysis with simple routines using ImageJ and Matlab. This merger of supramolecular chemistry and colloidal science offers a direct route towards light- and thermo-responsive colloidal assembly encoded in the surface-grafted monolayer.

A protocol for the synthesis and characterization of colloids coated with supramolecular moieties is described. These supramolecular colloids undergo self-assembly upon the activation of the hydrogen-bonds between the surface-anchored molecules by UV-light.

Síntesis y caracterización de supramoleculares Coloides

Control over colloidal assembly is of utmost importance for the development of functional colloidal materials with tailored structural and mechanical ...

Low-energy Cathodoluminescence for (Oxy)Nitride Phosphors

Nitride and oxynitride (Sialon) phosphors are good candidates for the ultraviolet and visible emission applications. High performance, good stability and flexibility of their emission properties can be achieved by controlling their composition and dopants. However, a lot of work is still required to improve their properties and to reduce the production cost. A possible approach is to correlate the luminescence properties of the Sialon particles with their local structural and chemical environment in order to optimize their growth parameters and find novel phosphors. For such a purpose, the low-voltage cathodoluminescence (CL) microscopy is a powerful technique. The use of electron as an excitation source allows detecting most of the luminescence centers, revealing their luminescence distribution spatially and in depth, directly comparing CL results with the other electron-based techniques, and investigating the stability of their luminescence properties under stress. Such advantages for phosphors characterization will be highlighted through examples of investigation on several Sialon phosphors by low-energy CL.

Low-energy Cathodoluminescence for OxyNitride Phosphors

An excellent chemical and luminescence stabilities of (oxy)nitride phosphors present it as an promising alternative to currently used sulfide and oxide phosphors. In this paper, we present the way to investigate its local luminescence properties using low-energy cathodoluminescence (CL).

Catodoluminiscencia de baja energía para (Oxy) Los fósforos de nitruro

Nitride and oxynitride (Sialon) phosphors are good candidates for the ultraviolet and visible emission applications. High performance, good stability and ...

Preparation and In Vitro Characterization of Dendrimer-based Contrast Agents for Magnetic Resonance Imaging

Paramagnetic complexes of gadolinium(III) with acyclic or macrocyclic chelates are the most commonly used contrast agents (CAs) for magnetic resonance imaging (MRI). Their purpose is to enhance the relaxation rate of water protons in tissue, thus increasing the MR image contrast and the specificity of the MRI measurements. Current clinically approved contrast agents are low molecular weight molecules that are rapidly cleared from the body. The use of dendrimers as carriers of paramagnetic chelators can play an important role in the future development of more efficient MRI contrast agents. Specifically, the increase in local concentration of the paramagnetic species results in a higher signal contrast. Furthermore, this CA provides a longer tissue retention time due to its high molecular weight and size. Here, we demonstrate a convenient procedure for the preparation of macromolecular MRI contrast agents based on poly(amidoamine) (PAMAM) dendrimers with monomacrocyclic DOTA-type chelators (DOTA &#8211; 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetate). The chelating unit was appended by exploiting the reactivity of the isothiocyanate (NCS) group towards the amine surface groups of the PAMAM dendrimer to form thiourea bridges. Dendrimeric products were purified and analyzed by means of nuclear magnetic resonance spectroscopy, mass spectrometry, and elemental analysis. Finally, high resolution MR images were recorded and the signal contrasts obtained from the prepared dendrimeric and the commercially available monomeric agents were compared.

Preparation and In Vitro Characterization of Dendrimer-based Contrast Agents for Magnetic Resonance Imaging

This protocol describes the preparation and characterization of a dendrimeric magnetic resonance imaging (MRI) contrast agent that carries cyclen-based macrocyclic chelates coordinating paramagnetic gadolinium ions. In a series of MRI experiments in vitro, this agent produced an amplified MRI signal when compared to the commercially available monomeric analogue.

Preparación y<em&gt; In Vitro</em&gt; Caracterización de los agentes de contraste basados ​​en dendrímeros de Imágenes por Resonancia Magnética

Paramagnetic complexes of gadolinium(III) with acyclic or macrocyclic chelates are the most commonly used contrast agents (CAs) for magnetic resonance ...

Influence of Hybrid Perovskite Fabrication Methods on Film Formation, Electronic Structure, and Solar Cell Performance

Hybrid organic/inorganic halide perovskites have lately been a topic of great interest in the field of solar cell applications, with the potential to achieve device efficiencies exceeding other thin film device technologies. Yet, large variations in device efficiency and basic physical properties are reported. This is due to unintentional variations during film processing, which have not been sufficiently investigated so far. We therefore conducted an extensive study of the morphology and electronic structure of a large number of CH3NH3PbI3 perovskite where we show how the preparation method as well as the mixing ratio of educts methylammonium iodide and lead(II) iodide impact properties like film formation, crystal structure, density of states, energy levels, and ultimately the solar cell performance.

We present an extensive study on the effects of different fabrication methods for organic/inorganic perovskite thin films by comparing crystal structures, density of states, energy levels, and ultimately the solar cell performance.

Influencia de los híbridos Métodos de Fabricación perovskita en la formación de película, Estructura electrónica y el rendimiento de la célula solar

Hybrid organic/inorganic halide perovskites have lately been a topic of great interest in the field of solar cell applications, with the potential to ...