Los autores agradecen a Svilen Bobev por su ayuda con los espectros de difracción de rayos X y K. Booksh de asistencia con el equipo Sputter.

1. Síntesis de árbol-como ZnO / CdSSe nanoestructuras <ol><li> El pretratamiento y el oro de recubrimiento de sustratos de zafiro NOTA: La película de oro actúa como un catalizador en el crecimiento de los nanocables de ZnO. <ol><li> diapositivas de zafiro limpio (un avión, 10 x 10 x 1 mm) en el 99,5% de etanol con 5 min de tratamiento con ultrasonidos para preparar el sustrato de Au pulverización catódica. </li><li> Depositar a 10 nm (± 2 nm) de espesor de película de oro sobre los portaobjetos de zafiro con un dispositivo de recubrimiento por pulverización catódica y objetivo de oro. </li></ol></li><li> Síntesis de nanocables de ZnO NOTA: La etapa de sonicación 1.2.2 resultados en una ZnO homogénea y carbono (/ C ZnO) mezcla. Después de mezclar, la mezcla cambia a un color gris. La etapa de compactación 1.2.3 asegura que el aire no está presente en la mezcla y que el ZnO y el carbono están en estrecho contacto. Después de CVD, una película blanca de nanocables de ZnO debe ser depositado sobre el sustrato, lado que mira hacia el barco. <ol><li> Mezclar 1 g de ZnO y nanopowder activcarbono ated (proporción en masa de 50:50) en 10 ml de etanol al 99,5% y mezclar bien con una espátula. </li><li> Sonicar la mezcla en un baño de agua a 20 ºC durante 30 minutos, y luego se seca en un horno durante ~ 5 horas a 80 ºC. </li><li> Colocar la mezcla ZnO / C en un bote de aluminio y compacto bien con una espátula. </li><li> Colocar los portaobjetos de zafiro recubiertas de oro en la parte superior de la embarcación de alúmina, con el lado recubierto de oro hacia abajo. Coloque el barco de alúmina en el centro del tubo de cuarzo en un horno de tubo horizontal. </li><li> Purgar el tubo de cuarzo durante 1 hora con Ar a un caudal de 40 sccm a temperatura ambiente (RT). Aumentar la temperatura de RT a 900 ºC a una velocidad de 80 ºC / min y mantener constante el caudal de argón. </li><li> Mantenga la temperatura a 900 ° C durante 2 horas. Abrir el tubo de cuarzo en ambos extremos mediante la eliminación de las entradas de gas tapón de goma y dejar que entre aire en el tubo para proporcionar oxígeno para la reacción. </li><li> Mantenga la temperatura de reacción a 900 ° C durante 3 horas con el rutapones bber quitados. Enfriar a temperatura ambiente a una velocidad de 10 ºC / min. </li><li> Tome el barco y la corredera fuera del horno. </li></ol></li><li> La deposición de ramas CdSSe en nanocables de ZnO NOTA: El barco de alúmina de CdS / Se fue representada en el centro del tubo de cuarzo. Los nanocables de ZnO preparados se enfrentan hacia arriba y eran de 10 cm abajo de la embarcación. Después de este segundo CVD, un / película de color amarillo anaranjado, que es la nanoestructura ZnO / CdSSe, debe ser depositado en la diapositiva. <ol><li> Mezclar 0,5 g de CdS y CdSe (CdS / Se) y polvo (fracción de masa de 50:50) y colocar la mezcla en un bote de alúmina. Compactar bien la mezcla. </li><li> Coloque el bote de alúmina de CdS / SE y la muestra de ZnO nanocables preparado previamente en el tubo de cuarzo. </li><li> Purgar el tubo con Ar a un caudal de 40 sccm a RT durante 1 hr. Aumentar la temperatura de reacción a 820 ºC a una velocidad de 80 ºC / min. Mantenga la temperatura a 820 ºC durante 30 min. </li><li> Enfriar a RT auna velocidad de 10 ºC / min. Tome el barco y la corredera fuera del horno. </li></ol></li><li> Síntesis de las muestras de control: ZnO y CdSSe nanocables <ol><li> Sintetizar nanocables de ZnO como en la sección 1.2, en las mismas condiciones experimentales. </li><li> Sintetizar nanocables CdSSe como en la sección 1.3, en las mismas condiciones experimentales, con la misma cantidad de CdS y composición CdSe, pero con una, tobogán zafiro recubierto de oro limpia como sustrato en lugar de la corredera de ZnO-depositado. </li></ol></li></ol> 2. Caracterización morfológica y cristalográfica <ol><li> Montar la muestra en la etapa SEM con una abrazadera y colocar la muestra en la cámara de vacío del instrumento SEM. Tomar imágenes de SEM en el modo de alta resolución con una distancia de trabajo de 12,0 mm a una tensión de 3 kV y una ampliación de entre 3,000X y 10.000X 11,12. </li><li> Tomar datos EDS con la misma muestra utilizando el detector de rayos X a la misma distancia de trabajo de12.0 mm. Poner el instrumento a modo de análisis y ajuste el voltaje a 20 kV, lo que resulta en una corriente de 20 a 40 mu 13. </li><li> Recoger los espectros de difracción de rayos X en un difractómetro de polvo de rayos X usando radiación filtrada Cu Ka (λ = 1,5418 Å) 11,12. </li></ol> 3. PL espectroscopia de emisión y Medidas de por vida PL Tiempo de resolver NOTA: Los espectros de PL y recuento de fotones individuales correlacionado con el tiempo (TCSPC) mediciones en RT se llevaron a cabo usando un amplificado Ti: oscilador de zafiro después de segunda generación armónica (SHG), produciendo un tren de 50 impulsos FSEC centradas en una longitud de onda de 400 nm y con una potencia de salida de 1,76 mW 14. <ol><li> Fijar la muestra en un soporte de muestras que posiciona la cara de muestra hasta el láser y al detector. Alinear el láser para centrarse en la muestra. Medir los espectros de emisión PL de las muestras de 500-nm a longitudes de onda 900 nm utilizando un espectrómetro de fibra. </li><li> Use un detector de fotón único (avalanche fotodiodo o célula fotoeléctrica) para medir los tiempos de vida PL tiempo de resolverse con un filtro de vidrio de color y un filtro de interferencia de paso de banda de 500 o 650 nm. </li><li> Insertar ZnO, CdSSe, o ZnO / CdSSe se desliza en el soporte de muestra. Medir los nanocables de ZnO puro con el filtro de paso de banda de 500 nm y las muestras CdSSe o ZnO / CdSSe con un filtro de paso de banda de 650 nm. </li><li> Utilice un contador de fotón único correlacionado con el tiempo o un osciloscopio rápido para medir los tiempos de vida de decaimiento de fluorescencia con resolución temporal. </li></ol>

<ol>
	<li>Swank, R. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Surface+Properties+of+II-VI.">Surface Properties of II-VI.</a> Compounds. Phys. Rev. 153 (3), 844-849 (1967).</li><li>Bagnall, D. 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=Optically+pumped+lasing+of+ZnO+at+room+temperature.">Optically pumped lasing of ZnO at room temperature.</a> Appl Phys. Lett. 70 (17), 2230-2232 (1997).</li><li>Zheng, Z. K., Xie, W., Lim, Z. S., You, L., Wang, J. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=CdS+sensitized+3D+hierarchical+TiO2/ZnO+heterostructure+for+efficient+solar+energy+conversion.">CdS sensitized 3D hierarchical TiO2/ZnO heterostructure for efficient solar energy conversion.</a> Sci. Rep. 4, (2014).</li><li>Anta, J. A., Guill&#233;n, E., Tena-Zaera, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=ZnO-Based+Dye-Sensitized+Solar+Cells.">ZnO-Based Dye-Sensitized Solar Cells.</a> J. Phys. Chem. C. 116 (21), 11413-11425 (2012).</li><li>Pelligra, C. I., Majewski, P. W., Osuji, C. O. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Large+area+vertical+alignment+of+ZnO+nanowires+in+semiconducting+polymer+thin+films+directed+by+magnetic+fields.">Large area vertical alignment of ZnO nanowires in semiconducting polymer thin films directed by magnetic fields.</a> Nanoscale. 5 (21), 10511-10517 (2013).</li><li>Reddy, N. K., Devika, M., Shpaisman, N., Ben-Ishai, M., Patolsky, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Synthesis+and+cathodoluminescence+properties+of+CdSe/ZnO+hierarchical+nanostructures.">Synthesis and cathodoluminescence properties of CdSe/ZnO hierarchical nanostructures.</a> J. Mater. Chem. 21 (11), 3858-3864 (2011).</li><li>Lee, Y. L., Chi, C. F., Liau, S. Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=CdS/CdSe+Co-Sensitized+TiO2+Photoelectrode+for+Efficient+Hydrogen+Generation+in+a+Photoelectrochemical+Cell.">CdS/CdSe Co-Sensitized TiO2 Photoelectrode for Efficient Hydrogen Generation in a Photoelectrochemical Cell.</a> Chem. Mater. 22 (3), 922-927 (2010).</li><li>Rinc&#243;n, M. E., S&#225;nchez, M., Ruiz-Garc&#237;a, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Photocorrosion+of+Coupled+CdS/CdSe+Photoelectrodes+Coated+with+ZnO:+Atomic+Force+Microscopy+and+X-Ray+Diffraction+Studies.">Photocorrosion of Coupled CdS/CdSe Photoelectrodes Coated with ZnO: Atomic Force Microscopy and X-Ray Diffraction Studies.</a> J. Electrochem. Soc. 145 (10), 3535-3544 (1998).</li><li>Leschkies, K. S., 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=Photosensitization+of+ZnO+Nanowires+with+CdSe+Quantum+Dots+for+Photovoltaic+Devices.">Photosensitization of ZnO Nanowires with CdSe Quantum Dots for Photovoltaic Devices.</a> Nano Lett. 7 (6), 1793-1798 (2007).</li><li>Gonzalez-Valls, I., Lira-Cantu, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Vertically-aligned+nanostructures+of+ZnO+for+excitonic+solar+cells:+a+review.">Vertically-aligned nanostructures of ZnO for excitonic solar cells: a review.</a> Energy Environ Sci. 2 (1), 19-34 (2009).</li><li>Zhu, 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=Synthesis+of+vertically+aligned+ultra-long+ZnO+nanowires+on+heterogeneous+substrates+with+catalyst+at+the+root.">Synthesis of vertically aligned ultra-long ZnO nanowires on heterogeneous substrates with catalyst at the root.</a> Nanotechnology. 23 (5), 055604 (2012).</li><li>Yang, P., 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=Controlled+Growth+of+ZnO+Nanowires+and+Their+Optical+Properties.">Controlled Growth of ZnO Nanowires and Their Optical Properties.</a> Adv. Func. Mater. 12 (5), 323-331 (2002).</li><li>Myung, Y., 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=Composition-Tuned+ZnO&#8722;CdSSe+Core&#8722;Shell+Nanowire+Arrays.">Composition-Tuned ZnO&#8722;CdSSe Core&#8722;Shell Nanowire Arrays.</a> ACS Nano. 4 (7), 3789-3800 (2010).</li><li>Pan, A., 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=Color-Tunable+Photoluminescence+of+Alloyed+CdSxSe1-x+Nanobelts.">Color-Tunable Photoluminescence of Alloyed CdSxSe1-x Nanobelts.</a> J. Am. Chem. Soc. 127 (45), 15692-15693 (2005).</li><li>Rakshit, T., Mondal, S. P., Manna, I., Ray, S. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=CdS-decorated+ZnO+nanorod+heterostructures+for+improved+hybrid+photovoltaic+devices.">CdS-decorated ZnO nanorod heterostructures for improved hybrid photovoltaic devices.</a> ACS Appl. Mater. Inter. 4 (11), 6085-6095 (2012).</li><li>Nan, W. N., 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=Crystal+Structure+Control+of+Zinc-Blende+CdSe/CdS+Core/Shell+Nanocrystals:+Synthesis+and+Structure-Dependent+Optical+Properties.">Crystal Structure Control of Zinc-Blende CdSe/CdS Core/Shell Nanocrystals: Synthesis and Structure-Dependent Optical Properties.</a> J. Am. Chem. Soc. 134 (48), 19685-19693 (2012).</li><li>Li, Z., Nieto-Pescador, J., Carson, A. J., Blake, J. C., Gundlach, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Efficient+Z-scheme+charge+separation+in+novel+vertically+aligned+ZnO/CdSSe+nanotrees.">Efficient Z-scheme charge separation in novel vertically aligned ZnO/CdSSe nanotrees.</a> Nanotechnology. 27 (13), 135401 (2016).</li></ol>

Datos y cifras en este artículo se citan en la bibliografía de la nanotecnología por Li et al. 17.

La alineación vertical de nanocables de ZnO (tallos) se basa en el crecimiento epitaxial sobre el sustrato. Nanocables de ZnO crecen preferentemente a lo largo de la &lt;0001&gt; dirección que coincide con la periodicidad de la a-plano de zafiro 12. Por lo tanto, el tipo y la calidad del sustrato son muy importantes. Diferentes espesores de la capa de oro sobre el substrato, de 5 nm a 20 nm, se han probado y no mostró diferencias significativas en el crecimiento de nanocables de ZnO. La longitud de los nan...

ZnO es un semiconductor II-VI que ofrece un intervalo de banda (BG) de 3,3 eV, una alta movilidad de electrones, y un 1,2 energía de enlace gran excitón. Se trata de un material semiconductor abundante, con una gran cantidad de aplicaciones presentes y futuras en dispositivos ópticos, células solares, y fotocatálisis. Sin embargo, ZnO es transparente, lo que limita su aplicación en la gama espectral visible. Por lo tanto, materiales absorbentes de luz visible, tales como semiconductores estrecha brecha de 3, 4 moléculas de colorante, y polímeros fotosensibles 5, con frecuencia han sido empleados para sensibilizar ZnO a la absorción de la luz visible. CdS (BG 2.43 eV) y CdSe (BG 1.76 eV) son comunes semiconductores II-VI-gap estrecho y se han investigado intensamente. Los parámetros de BG y de celosía de la aleación ternaria CdSSe se pueden ajustar mediante la variación de las relaciones molares de los componentes de VI 6,7. nanocompuestos ZnO / CdSSe se han reportado para dar lugar a photov eficienteconversión de energía oltaic 8,9. La combinación de la vía de transporte de electrones eficiente de los nanocables de ZnO alineados verticalmente hacia un sustrato con la mejora de la absorción de luz visible de las ramas CdSSe condujo a la transferencia eficiente de electrones entre el tallo y las ramas 9,10. Por lo tanto, se sintetizó una nueva nanoestructura ZnO / CdSSe en forma de árbol, donde nanocables de ZnO alineados verticalmente están decoradas con ramas CdSSe. Este material compuesto puede actuar como un bloque de construcción para los nuevos dispositivos de conversión de energía solar. Este protocolo describe cómo se cultivan las matrices de nanocables de ZnO sobre un sustrato de zafiro mediante la deposición química de vapor de un solo paso (CVD) a partir de polvos de ZnO y C, siguiendo un procedimiento que ha sido previamente publicado 11. Tras el crecimiento de los nanocables de ZnO, un segundo paso de CVD se emplea para crecer ramas CdSSe en los nanocables de ZnO. Empleamos de difracción de rayos X en polvo (XRD), microscopía electrónica de barrido (SEM), yespectroscopia de rayos X de energía dispersiva (EDS) para medir la estructura cristalina, morfología y composición de los nanotrees ZnO / CdSSe (NTs). El mecanismo de transferencia de propiedades ópticas y portador de carga entre las ramas y el tallo había sido investigada por la fotoluminiscencia (PL) y espectroscopia de mediciones de toda la vida PL tiempo de resolverse.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>ZnO</td>
			<td>Sigma Aldrich</td>
			<td>1314-13-2</td>
			<td></td>
		</tr>
		<tr>
			<td>Activated Carbon</td>
			<td>Alfa</td>
			<td>231-153-3</td>
			<td></td>
		</tr>
		<tr>
			<td>CdSe</td>
			<td>Sigma Aldrich</td>
			<td>1306-24-7</td>
			<td></td>
		</tr>
		<tr>
			<td>CdS</td>
			<td>Sigma Aldrich</td>
			<td>1306-23-6</td>
			<td></td>
		</tr>
		<tr>
			<td>Sapphire</td>
			<td>MTI</td>
			<td>2SP</td>
			<td>a-plane, 10 &#215; 10 &#215; 1 mm</td>
		</tr>
		<tr>
			<td>Furnace</td>
			<td>Lindberg Blue M</td>
			<td>SSP</td>
			<td></td>
		</tr>
		<tr>
			<td>Scanning electron microscope</td>
			<td>Hitachi</td>
			<td>S5700</td>
			<td>assembled with an Oxford Inca X-act detector</td>
		</tr>
		<tr>
			<td>X-ray powder diffractometer&#160;</td>
			<td>Rigaku&#160;</td>
			<td>MiniFlex</td>
			<td>filtered Cu K&#945; radiation (&#955;=1.5418 &#197;)</td>
		</tr>
		<tr>
			<td>Amplified Ti:sapphire oscillator&#160;</td>
			<td>Coherent Mantis</td>
			<td>Coherent Legend-Elite</td>
			<td></td>
		</tr>
		<tr>
			<td>Single photon detection module&#160;</td>
			<td>ID Quantique</td>
			<td>ID-100</td>
			<td></td>
		</tr>
		<tr>
			<td>Sputter coater</td>
			<td>Cressington</td>
			<td>308</td>
			<td>assembled with gold target</td>
		</tr>
		<tr>
			<td>Fiber probe spectrometer</td>
			<td>Photon Control</td>
			<td>SPM-002</td>
			<td></td>
		</tr>
		<tr>
			<td>Colored Glass Filter</td>
			<td>Thorlabs</td>
			<td>FGB37-A - &#216;25 mm BG40</td>
			<td>AR Coated: 350 - 700 nm&#160;</td>
		</tr>
		<tr>
			<td>Compressed argon gas</td>
			<td>Keen</td>
			<td>7440-37-1</td>
			<td></td>
		</tr>
	</tbody>
</table>

synthesis of hierarchical zno/cdsse heterostructure nanotrees

Un procedimiento de deposición de vapor químico de dos etapas se emplea aquí para preparar jerárquicos ZnO / CdSSe hetero-nanoestructuras en forma de árbol. Las estructuras se componen de ramas CdSSe cultivadas en nanocables de ZnO que están alineadas verticalmente sobre un sustrato de zafiro transparente. La morfología se midió a través de microscopía electrónica de barrido. La estructura cristalina se determinó por análisis de difracción de polvo de rayos X. Tanto el ZnO tallo y las ramas CdSSe tener una estructura de cristal predominantemente wurtzita. La relación molar de S y de Se en las ramas CdSSe se midió por espectroscopia de rayos X de dispersión de energía. Las ramas CdSSe dan lugar a una fuerte absorción de la luz visible. Fotoluminiscencia (PL) espectroscopía demostró que el tallo y las ramas forman una heterounión de tipo II. mediciones de toda la vida PL mostraron una disminución en el tiempo de vida de la emisión de los árboles, en comparación con la emisión de ZnO individuo tallos o ramas CdSSe e indicar la transferencia de carga rápida entre CdSSe y ZnO. el verticamente alineado ZnO se debe proporcionar una vía de transporte de electrones directa al sustrato y permitir la separación de la carga eficiente después de fotoexcitación por la luz visible. La combinación de las propiedades mencionadas anteriormente hace ZnO / CdSSe nanotrees candidatos prometedores para aplicaciones en células solares, la fotocatálisis, y dispositivos opto-electrónicos.

La Figura 1 muestra el mecanismo de crecimiento de ZnO / CdSSe NT. El procedimiento consistió en un proceso catalítico de vapor-líquido-sólido (VLS) seguido de un crecimiento no catalítica vapor-sólido (VS). En el primer paso VLS, ZnO y C reaccionan en la atmósfera Ar, resultando en Zn metálico y óxido de carbono. Zn se disuelve posteriormente en el precursor de oro sobre el sustrato de zafiro. nanocables de ZnO crecen desde el Zn disuelto y oxígeno residual. E...

Watch this Scientific Journal Video about Synthesis of Hierarchical ZnO/CdSSe Heterostructure Nanotrees at JoVE.com

Synthesis of Hierarchical ZnO/CdSSe Heterostructure Nanotrees

A continuación, preparamos y caracterizar nuevos jerárquicos nanoestructuras de ZnO / CdSSe forma de árbol, donde las ramas CdSSe se cultivan en nanocables de ZnO alineados verticalmente. Los nanotrees resultantes son un material potencial para la conversión de energía solar y otros dispositivos optoelectrónicos.

Síntesis del jerárquica ZnO / CdSSe heteroestructura Nanotrees

A two-step chemical vapor deposition procedure is here employed to prepare tree-like hierarchical ZnO/CdSSe hetero-nanostructures. The structures are ...

synthesis-of-hierarchical-znocdsse-heterostructure-nanotrees

Research

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Chemistry

9.9K vistas.  University of Delaware.  A continuación, preparamos y caracterizar nuevos jerárquicos nanoestructuras de ZnO / CdSSe forma de árbol, donde las ramas CdSSe se cultivan en nanocables de ZnO alineados verticalmente. Los nanotrees resultantes son un material potencial para la conversión de energía solar y otros dispositivos optoelectrónicos. 

Video: Synthesis of Hierarchical ZnO/CdSSe Heterostructure Nanotrees

Synthesis of Immunotargeted Magneto-plasmonic Nanoclusters

Magnetic and plasmonic properties combined in a single nanoparticle provide a synergy that is advantageous in a number of biomedical applications including contrast enhancement in novel magnetomotive imaging modalities, simultaneous capture&#160;and detection of circulating tumor cells (CTCs),&#160;and multimodal molecular imaging combined with photothermal therapy of cancer cells. These applications have stimulated significant interest in development of protocols for synthesis of magneto-plasmonic nanoparticles with optical absorbance in the near-infrared (NIR) region and a strong magnetic moment. Here, we present a novel protocol for synthesis of such hybrid nanoparticles that is based on an oil-in-water microemulsion method. The unique feature of the protocol described herein is synthesis of magneto-plasmonic nanoparticles of various sizes from primary blocks which also have magneto-plasmonic characteristics. This approach yields nanoparticles with a high density of magnetic and plasmonic functionalities which are uniformly distributed throughout the nanoparticle volume. The hybrid nanoparticles can be easily functionalized by attaching antibodies through the Fc moiety leaving the Fab portion that is responsible for antigen binding available for targeting.

Here, we describe a protocol for synthesis of magneto-plasmonic nanoparticles with a strong magnetic moment and a strong near-infrared (NIR) absorbance. The protocol also includes antibody conjugation to the nanoparticles through the Fc moiety for various biomedical applications which require molecular specific targeting.

Nanoclusters Síntesis de Immunotargeted Magneto-plasmónica

Magnetic and plasmonic properties combined in a single nanoparticle provide a synergy that is advantageous in a number of biomedical applications ...

Investigación

Química

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 ...

Synthesis of Indoxyl-glycosides for Detection of Glycosidase Activities

Indoxyl glycosides proved to be valuable and versatile tools for monitoring glycosidase activities. Indoxyls are released by enzymatic hydrolysis and are rapidly oxidized, for example by atmospheric oxygen, to indigo type dyes. This reaction enables fast and easy screening in vivo without isolation or purification of enzymes, as well as rapid tests on agar plates or in solution (e.g., blue-white screening, micro-wells) and is used in biochemistry, histochemistry, bacteriology and molecular biology. Unfortunately the synthesis of such substrates proved to be difficult, due to various side reactions and the low reactivity of the indoxyl hydroxyl function. Especially for glucose type structures low yields were observed. Our novel approach employs indoxylic acid ester as key intermediates. Indoxylic acid esters with varied substitution patterns were prepared on scalable pathways. Phase transfer glycosylations with those acceptors and peracetylated glycosyl halides can be performed under common conditions in high yields. Ester cleavage and subsequent mild silver mediated glycosylation yields the peracetylated indoxyl glycosides in high yields. Finally deprotection is performed according to Zempl&#233;n.

Indoxyl glycosides are well-established and widely used tools for enzyme screening and enzyme activity monitoring. Especially for glucose type structures previous syntheses proved to be challenging and low yielding. Our novel approach employs indoxylic acid esters as precious intermediates to yield a considerable number of indoxyl glycosides in good yields.

Síntesis de indoxil-glucósidos para la detección de glucosidasa Actividades

Indoxyl glycosides proved to be valuable and versatile tools for monitoring glycosidase activities. Indoxyls are released by enzymatic hydrolysis and are ...

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 ...

Hydroquinone Based Synthesis of Gold Nanorods

Gold nanorods are an important kind of nanoparticles characterized by peculiar plasmonic properties. Despite their widespread use in nanotechnology, the synthetic methods for the preparation of gold nanorods are still not fully optimized. In this paper we describe a new, highly efficient, two-step protocol based on the use of hydroquinone as a mild reducing agent. Our approach allows the preparation of nanorods with a good control of size and aspect ratio (AR) simply by varying the amount of hexadecyl trimethylammonium bromide (CTAB) and silver ions (Ag+) present in the "growth solution". By using this method, it is possible to markedly reduce the amount of CTAB, an expensive and cytotoxic reagent, necessary to obtain the elongated shape. Gold nanorods with an aspect ratio of about 3 can be obtained in the presence of just 50 mM of CTAB (versus 100 mM used in the standard protocol based on the use of ascorbic acid), while shorter gold nanorods are obtained using a concentration as low as 10 mM.

This paper describes a protocol for the synthesis of gold nanorods, based on the use of hydroquinone as reducing agent, plus the different mechanisms for controlling their size and aspect ratio.

Hidroquinona basado Síntesis de oro Nanorods

Gold nanorods are an important kind of nanoparticles characterized by peculiar plasmonic properties. Despite their widespread use in nanotechnology, the ...

Synthesis and Mass Spectrometry Analysis of Oligo-peptoids

Peptoids are sequence-controlled peptide-mimicking oligomers consisting of N-alkylated glycine units. Among many potential applications, peptoids have been thought of as a type of molecular information storage. Mass spectrometry analysis has been considered the method of choice for sequencing peptoids. Peptoids can be synthesized via solid phase chemistry using a repeating two-step reaction cycle. Here we present a method to manually synthesize oligo-peptoids and to analyze the sequence of the peptoids using tandem mass spectrometry (MS/MS) techniques. The sample peptoid is a nonamer consisting of alternating N-(2-methyloxyethyl)glycine (Nme) and N-(2-phenylethyl)glycine (Npe), as well as an N-(2-aminoethyl)glycine (Nae) at the N-terminus. The sequence formula of the peptoid is Ac-Nae-(Npe-Nme)4-NH2, where Ac is the acetyl group. The synthesis takes place in a commercially available solid-phase reaction vessel. The rink amide resin is used as the solid support to yield the peptoid with an amide group at the C-terminus. The resulting peptoid product is subjected to sequence analysis using a triple-quadrupole mass spectrometer coupled to an electrospray ionization source. The MS/MS measurement produces a spectrum of fragment ions resulting from the dissociation of charged peptoid. The fragment ions are sorted out based on the values of their mass-to-charge ratio (m/z). The m/z values of the fragment ions are compared against the nominal masses of theoretically predicted fragment ions, according to the scheme of peptoid fragmentation. The analysis generates a fragmentation pattern of the charged peptoid. The fragmentation pattern is correlated to the monomer sequence of the neutral peptoid. In this regard, MS analysis reads out the sequence information of the peptoids.

A protocol is described for the manual synthesis of oligo-peptoids followed by sequence analysis by mass spectrometry.

Síntesis y análisis de espectrometría de masas de peptoides Oligo

Peptoids are sequence-controlled peptide-mimicking oligomers consisting of N-alkylated glycine units. Among many potential applications, peptoids have ...

Synthesis of Substrate-Bound Au Nanowires Via an Active Surface Growth Mechanism

Advancing synthetic capabilities is important for the development of nanoscience and nanotechnology. The synthesis of nanowires has always been a challenge, as it requires asymmetric growth of symmetric crystals. Here, we report a distinctive synthesis of substrate-bound Au nanowires. This template-free synthesis employs thiolated ligands and substrate adsorption to achieve the continuous asymmetric deposition of Au in solution at ambient conditions. The thiolated ligand prevented the Au deposition on the exposed surface of the seeds, so the Au deposition only occurs at the interface between the Au seeds and the substrate. The side of the newly deposited Au nanowires is immediately covered with the thiolated ligand, while the bottom facing the substrate remains ligand-free and active for the next round of Au deposition. We further demonstrate that this Au nanowire growth can be induced on various substrates, and different thiolated ligands can be used to regulate the surface chemistry of the nanowires. The diameter of the nanowires can also be controlled with mixed ligands, in which another &#34;bad&#34; ligand could turn on the lateral growth. With the understanding of the mechanism, Au nanowire-based nanostructures can be designed and synthesized.

We report a solution-based method to synthesize substrate-bound Au nanowires. By tuning the molecular ligands used during the synthesis, the Au nanowires can be grown from various substrates with different surface properties. Au nanowire-based nanostructures can also be synthesized by adjusting the reaction parameters.

Síntesis de nanocables de Au sustrato enlazado mediante un mecanismo activo crecimiento superficial

Advancing synthetic capabilities is important for the development of nanoscience and nanotechnology. The synthesis of nanowires has always been a ...

Solid-phase Synthesis of [4.4] Spirocyclic Oximes

A convenient synthetic route for spirocyclic heterocycles is well sought after due to the molecule&#39;s potential use in biological systems. By means of solid-phase synthesis, regenerating Michael (REM) linker strategies, and 1,3-dipolar cycloaddition, a library of structurally similar heterocycles, both with and without a spirocyclic center, can be constructed. The main advantages of the solid-support synthesis are as follows: first, each reaction step can be driven to completion using a large excess of reagents resulting in high yields; next, the use of commercially available starting materials and reagents keep the costs low; finally, the reaction steps are easy to purify via simple filtration. The REM linker strategy is attractive because of its recyclability and traceless nature. Once a reaction scheme is completed, the linker can be reused multiple times. In a typical solid-phase synthesis, the product contains either a part of or the whole linker, which can prove undesirable. The REM linker is &#34;traceless&#34; and the point of attachment between the product and the polymer is indistinguishable. The high diastereoselectivity of the intramolecular 1,3-dipolar cycloaddition is well documented. Limited by the insolubility of the solid support, the reaction progression can only be monitored by a change in the functional groups (if any) via infrared (IR) spectroscopy. Thus, the structural identification of intermediates cannot be characterized by conventional nuclear magnetic resonance (NMR) spectroscopy. Other limitations to this method stem from the compatibilities of the polymer/linker to the desired chemical reaction scheme. Herein we report a protocol that allows for the convenient production of spirocyclic heterocycles that, with simple modifications, can be automated with high-throughput techniques.

Here we present a protocol to demonstrate an efficient method for the synthesis of spirocyclic heterocycles. The five-step process utilizes solid-phase synthesis and regenerating Michael linker strategies. Generally difficult to synthesize, we present a customizable method for the synthesis of spirocyclic molecules otherwise inaccessible to other modern approaches.

Síntesis en fase sólida de oximas espirocícliclos [4,4]

A convenient synthetic route for spirocyclic heterocycles is well sought after due to the molecule&#39;s potential use in biological systems. By means of ...

Synthesis and Characterization of Amphiphilic Gold Nanoparticles

Gold nanoparticles covered with a mixture of 1-octanethiol (OT) and 11-mercapto-1-undecane sulfonic acid (MUS) have been extensively studied because of their interactions with cell membranes, lipid bilayers, and viruses. The hydrophilic ligands make these particles colloidally stable in aqueous solutions and the combination with hydrophobic ligands creates an amphiphilic particle that can be loaded with hydrophobic drugs, fuse with the lipid membranes, and resist nonspecific protein adsorption. Many of these properties depend on nanoparticle size and the composition of the ligand shell. It is, therefore, crucial to have a reproducible synthetic method and reliable characterization techniques that allow the determination of nanoparticle properties and the ligand shell composition. Here, a one-phase chemical reduction, followed by a thorough purification to synthesize these nanoparticles with diameters below 5 nm, is presented. The ratio between the two ligands on the surface of the nanoparticle can be tuned through their stoichiometric ratio used during synthesis. We demonstrate how various routine techniques, such as transmission electron microscopy (TEM), nuclear magnetic resonance (NMR), thermogravimetric analysis (TGA), and ultraviolet-visible (UV-Vis) spectrometry, are combined to comprehensively characterize the physicochemical parameters of the nanoparticles.

Amphiphilic gold nanoparticles can be used in many biological applications. A protocol to synthesize gold nanoparticles coated by a binary mixture of ligands and a detailed characterization of these particles is presented.

Síntesis y caracterización de nanopartículas de oro anfifílicas

Gold nanoparticles covered with a mixture of 1-octanethiol (OT) and 11-mercapto-1-undecane sulfonic acid (MUS) have been extensively studied because of ...

Hierarchical and Programmable One-Pot Oligosaccharide Synthesis

This article presents a general experimental protocol for programmable one-pot oligosaccharide synthesis and demonstrates how to use Auto-CHO software for generating potential synthetic solutions. The programmable one-pot oligosaccharide synthesis approach is designed to empower fast oligosaccharide synthesis of large amounts using thioglycoside building blocks (BBLs) with the appropriate sequential order of relative reactivity values (RRVs). Auto-CHO is a cross-platform software with a graphical user interface that provides possible synthetic solutions for programmable one-pot oligosaccharide synthesis by searching a BBL library (containing about 150 validated and &#62;50,000 virtual BBLs) with accurately predicted RRVs by support vector regression. The algorithm for hierarchical one-pot synthesis has been implemented in Auto-CHO and uses fragments generated by one-pot reactions as new BBLs. In addition, Auto-CHO allows users to give feedback for virtual BBLs to keep valuable ones for further use. One-pot synthesis of stage-specific embryonic antigen 4 (SSEA-4), which is a pluripotent human embryonic stem cell marker, is demonstrated in this work.

This protocol demonstrates how to use the Auto-CHO software for hierarchical and programmable one-pot synthesis of oligosaccharides. It also describes the general procedure for RRV determination&#160;experiments and one-pot glycosylation of SSEA-4.

Síntesis jerárquica y programable de oligosacáridos de una olla

This article presents a general experimental protocol for programmable one-pot oligosaccharide synthesis and demonstrates how to use Auto-CHO software for ...