Este trabajo fue apoyado por la Fundación Nacional de Investigación de Corea (2013R1A1A1061387) y fondo de investigación KU-KIST.

1. Preparación de Precursor <ol><li> Preparación de óxido de grafeno (GO): <ol><li> Preparación GO utilizando el método de Hummer 14 modificado <ol><li> Añadir 3,0 g de escamas de grafito a una mezcla de H 2 SO 4 concentrado / H 3 PO 4 (360: 40 ml) a TA. (Nota: Especial cuidado se debe tomar durante el uso de ácidos fuertes H 2 SO 4 y H 3 PO 4.) </li><li> Añadir KMnO 4 (18,0 g) lentamente con agitación y enfriamiento en un baño de hielo para mantener la temperatura de la mezcla de reacción a &lt;35 ° C. (La solución convertirse pegajosa con un mayor tiempo de reacción, la necesidad de utilizar el método adecuado para mantener la agitación eficiente.) (Nota: Especial cuidado se debe tener al tiempo que añade KMnO4 debido a la reacción exotérmica.) </li><li> Se agita durante 12 horas a 50 ° C y luego se enfría hasta TA y verter mezcla de reacción sobre hielo (400 ml) que contenía 30% de H 2 O 2 (3 ml). </li><li> Se filtra la reaction mezcla utilizando un metal US Standard prueba tamiz (300 micras) para eliminar el grafito que no ha reaccionado y centrifugar la (velocidad de 4722 xg durante 2 hr) filtrado para eliminar el sobrenadante. </li><li> Repetir la etapa de centrifugación con 200 ml de agua, 200 ml de HCl al 30%, 200 ml de etanol, y agua destilada otra vez hasta pH del alcance solución a 5.0-6.0. </li><li> Liofilizar las soluciones finales para producir un polvo GO esponjosa. </li><li> Con el fin de obtener una solución de GO nanométricas, se disuelven 20 mg de polvo de GO en 40 ml triple del agua destilada (&gt; 18 mO), y luego exfoliar por sonicación prolongada (35% de la amplitud, 500 W, 2 hr) hasta que toda la distribución del tamaño de convertirse por debajo de 150 nm, a continuación, centrifugar dos veces (que 10.625 xg velocidad, 15 min) para eliminar los precipitados (grandes hojas pasan ONU-exfoliada). </li></ol></li></ol></li><li> Preparación de nanopartículas plasmónica <ol><li> Preparación de AuNPs <ol><li> Forma esférica nanopartículas de oro estabilizadas con citrato (AunPs, OD = 1,0) de 30 nm de tamaño de partículas se utilizó para la reducción de r-GO. </li></ol></li><li> Preparación de AuNRs 15 <ol><li> Preparar la solución de semillas mediante la adición de una solución recién preparada 0,6 ml enfriada con hielo de NaBH 4 solución (0,01 M) en una solución acuosa de redacción solución mezcla de 0,25 ml de HAuCl4 (0,01 M) y 9,75 ml de bromuro de cetiltrimetilamonio (CTAB, 0,1 M ). </li><li> Se agita la mezcla resultante vigorosamente durante 0,5 minutos y luego mantenerla a 28 ° C durante 3 horas. </li><li> Preparar la solución de crecimiento mediante la mezcla de 475 ml de CTAB (0,1 M), 3 ml de AgNO 3 (0,01 M) y 20 ml de HAuCl4 (0,01 M). </li><li> A continuación, añadir 3,2 ml recién preparada de ácido ascórbico (0,01 M) a la mezcla seguido por la adición de 0,8 ml de una solución acuosa de HCl (1,0 M). </li><li> En el paso final añadir 3,2 ml de solución de semilla para la solución de crecimiento a 28 ° C y someter la mezcla de reacción a la inversión rápida durante unos segundos. Finalmente, keep la mezcla resultante en reposo durante al menos 6 h. </li><li> Analizar los AuNRs preparados con espectroscopía UV-visible para los máximos de absorción (λ max) y el análisis TEM (típicamente la relación λ max y el aspecto se encontró que era 730 nm y 3,5, respectivamente). </li></ol></li><li> Preparación de AuNSs 16 <ol><li> Preparar la solución acuosa de stock de 4- (2-hidroxietil) -1-piperazinetanosulfónico ácido (HEPES) con la concentración de 100 mM, y ajustar el pH a 7,4 a 25 ° C mediante la adición de solución de NaOH 1,0 M. </li><li> Mezclar 20 ml de tampón de fosfato (100 mM) con 30 ml de ácido 2- [4- (2-hidroxietil) -1-piperazinil] etanosulfónico (100 mM). </li><li> A continuación, añadir 500 l de trihidrato de cloruro de oro (III) (20 mM) a la mezcla anterior y mantenerla en 28,5 ° C durante 30 minutos en baño de agua. Después se pudieron observar cambios de color Solución de color amarillo claro a azul verdoso 30 min. </li><li> Centrifugar la solución a una velocidad de 8928 xg durante 30 min y dispersarlos precipitados en agua destilada. </li><li> Por último, analizar la AuNSs preparado con espectroscopía UV-visible para los máximos de absorción (λ max) y el análisis de TEM para la confirmación partículas de tamaño que se encontró que 740 nm y 30 nm, respectivamente. </li></ol></li></ol></li></ol> 2. Preparación de r-GO Usando luz visible y AuNPs <ol><li> Añadir 1 ml de nanopartículas plasmónicas (ABS 1.0 a 520 nm para AuNPs, Abs 1,0 a 750 nm para AuNRs, y Abs 1,0 a 730 nm para AuNSs, respectivamente) y 100 l de hidróxido de amonio (28%, w / v%) a 10 ml de solución GO (OD 1,0 a 230 nm, 0,125 mg ml -1) se coloca en un reactor de vidrio Pyrex equipado con una camisa de circulación de agua. </li><li> Irradiar la mezcla con la lámpara de Xe (densidad de potencia de 1,56 W cm -2) durante 30 min con la circulación de agua a través de la chaqueta de circulación de agua para mantener la temperatura a 25 ° C y centrifugar la solución a una velocidad de 10.625 xg durante 15 min aeliminar las nanopartículas de oro. </li><li> Tome el sobrenadante que contiene el r-GO para analizar con UV-Visible espectrofotómetro (r-GO debe mostrar la banda de absorción característica a 270 nm) en el rango de 200-900 nm preparado. </li></ol> 3. Objetivo Detección de ADN utilizando r-GO Solution 17 <ol><li> Por extinción de fluorescencia, añadir 20 l de 10 -6 ssDNA modificado con Cy3 M (5&#39;-CTT ATC ATC AAT TCA TAA CAA TAA TCC CTC-Cy3-3 &#39;) en una solución de GO o r-GO contiene 25 l de GO (0.125 mg ml -1) o r-GO (0,125 mg ml -1) en 1,955 l de solución 0,3 M PBS (tampón fosfato 10 mM, NaCl 0,3 M) y se incuba durante 10 min a TA. </li><li> Medir la intensidad de fluorescencia de estas muestras con espectrofluorómetro (λ = 529 nm ex). </li><li> Para la detección de objetivos, añadir 200 l de solución de oligonucleótido diana (5&#39;-GAG GGA TTA TTG TTA AAT TCA GAT AAG GAT- 3 &#39;) en tres concentraciones diferentes (10 -6 &lt;/ sup&gt; M, 10 -7 M, 10 -8 M) en la solución o r GO-GO que contiene 20 l de 10 -6 M ssDNA-Cy3, 25 l de GO o r-GO (0,125 mg ml -1) y 1.755 l de 0,3 M de PBS para el experimento de recuperación de fluorescencia. 17 Notas: Fuentes de luz y Reactor La luz visible (400-780 nm) de origen. La luz visible irradia a través del reactor vidrio Pyrex (diámetro ventana = 1,1 cm) que contiene la solución GO utilizando lámpara de Xe (1,56 W / cm2 de potencia). La energía fotónica aplicada al reactor se calcula que es 4,8 × 10 21 fotones por min (Figura 2A-2C). Infrarrojo cercano (NIR) láser. Láser NIR (diámetro ventana = 13,2 cm) con una densidad de potencia de 0,36 W / cm2, y longitud de onda de funcionamiento de 808 nm se ha utilizado como la fuente de luz del infrarrojo cercano para reacciones de reducción GO (Figura 2E). La energía de los fotones se calcula para ser 2,43 × 10 21 fotones por min. Reactor: reactor de vidrio Pyrex (diámetro ventana = 1,1 cm; volumen de reacción = 10 ml) equipado con una camisa de circulación de agua se utiliza tanto para la luz visible y la luz NIR irradiados reacciones de reducción GO (Figura 2F). </li></ol>

<ol>
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No tenemos nada que revelar.

Irradiación de luz visible sobre una solución GO durante 30 minutos con nanopartículas de oro (AuNPs, AuNSs y AuNRs) mostró los rápidos cambios de color de la luz de color amarillo-marrón a negro (Figura 1). Para obtener el producto r-GO de alta pureza con un alto rendimiento, existen dos factores importantes necesitan seguir. Uno de ellos es el uso de AuNPs como un catalizador de plasmónica eficiente, ya AuNPs pueden absorber fuertemente la luz visible entre otras estructuras (es decir,...

<html> Método 1 y el vapor químico a base La primera scotch-tape desarrollado deposición 2 eran excelentes métodos para producir el estado prístino de un grafeno, pero la formación de la capa síntesis a gran grafeno escala o de grafeno en la superficie con amplia área se han considerado como una limitación clave de la . los métodos anteriores 3 Uno de posible solución para gran escala la síntesis de r-GO será método sintético químico húmedo que requiere en primer lugar las reacciones con oxidantes fuertes, extensa tratamiento físico tales como sonicación para producir IR hoja, y finalmente la reducción de funcionalidades de oxígeno tales como hidroxilo, epóxido y grupos carbonilo en GO es esencial a fin de recuperar sus propiedades físicas originales. 4 En su mayoría, se llevó a la reducción de salir con cualquiera de los métodos químicos usando hidrazina o sus derivados 5 o por el método de tratamiento térmico (550-1,100 ° C) en una atmósfera inerte o reductora. 6 jove_content &quot;&gt; Estos procesos requieren los productos químicos tóxicos, largo tiempo de reacción y la temperatura alta que aumentó la demanda total de energía para la síntesis de la r-GO. 7 Si bien los procesos de reducción de foto-irradiación como, proceso 8 foto-térmica inducida por UV usando un xenón pulsada flash, 9 pulsos láser asistida 10 y foto-térmica de calefacción con luces de flash de la cámara 11 también han sido reportados para la preparación de r-GO. En general, la baja eficiencia de conversión de los métodos fotoinducidas propaga al uso de UV o pulsada irradiación láser que puede entregar alta energía fotónica. La baja energía de los fotones de la luz visible limita su uso y no llamaron mucho para la síntesis de la r-GO. Excelentes propiedades de absorción de la luz de las nanopartículas plasmónicas en las regiones visibles y / o NIR puede mejorar en gran medida los inconvenientes actuales del uso de la luz visible para la síntesis de la r-GO. 12,13 condiciones suaves de reacción, tiempo de reacción corto y el uso limitado de ch tóxicosemicals podrían hacer que el plasmón inducida luz visible asistida reducción fotocatalítica de GO como un método alternativo de utilidad. En presente método, se describe el método sintético r-GO eficiente y sencilla utilizando nanopartículas plasmónicas y luz visible. Se encontró que el progreso de la reacción a ser fuertemente dependiente de las estructuras de nanopartículas plasmónicas tales como nanopartículas esféricas de oro (AuNPs), nanorods oro (AuNRs), y nanoestrellas de oro (AuNSs). El uso de AuNPs mostró la reducción más eficiente de GO y las nanopartículas son fácilmente extraíbles y reciclables para el uso repetido (Figura 1). El r-GO sintetizó usando luz visible y AuNPs mostró casi igual calidad en comparación con el r-GO preparado por método químico bien conocido (hidracina) como se ha demostrado mediante el uso de varias mediciones analíticas y el método de detección de ADN basado en la fluorescencia de temple / recuperación.

<table border="0" cellpadding="0" cellspacing="0">
	<tbody>
		<tr>
			<td>Cy3 modifeid ssDNA</td>
			<td>IDT(Iowa, USA)</td>
			<td></td>
			<td>HPLC purified by IDT</td>
		</tr>
		<tr>
			<td>Gold nanoparticles (30 nm)</td>
			<td>Ted Pella, Inc(Redding, CA, USA).</td>
			<td>15706-20</td>
			<td>colloidal solution</td>
		</tr>
		<tr>
			<td>4-(2-hydroxyethyl)-1-piperazineethane sulfonic acid (HEPES) (99.5%)</td>
			<td>Sigma-Aldrich (St. Louis, MO, USA)</td>
			<td>7365-45-9</td>
			<td></td>
		</tr>
		<tr>
			<td>Gold(III)Chloride Hydrate (99.999%)</td>
			<td>Sigma-Aldrich (St. Louis, MO, USA)</td>
			<td>&#160;27988-77-8</td>
			<td>strongly hygroscopic</td>
		</tr>
		<tr>
			<td>Sodium Borohydride (99.99%)</td>
			<td>Sigma-Aldrich (St. Louis, MO, USA)</td>
			<td>16940-66-2</td>
			<td></td>
		</tr>
		<tr>
			<td>Hexadecyltrimethylammonium bromide (&#8805;99%)</td>
			<td>Sigma-Aldrich (St. Louis, MO, USA)</td>
			<td>57-09-0</td>
			<td></td>
		</tr>
		<tr>
			<td>L-Ascorbic Acid(&#8805;99.0%)</td>
			<td>Sigma-Aldrich (St. Louis, MO, USA)</td>
			<td>50-81-7</td>
			<td></td>
		</tr>
		<tr>
			<td>Sodium Chloride (99.5%)</td>
			<td>Sigma-Aldrich (St. Louis, MO, USA)</td>
			<td>7647-14-5</td>
			<td></td>
		</tr>
		<tr>
			<td>Silver Nitrate&#160; (&#8805;99.0%)</td>
			<td>Sigma-Aldrich (St. Louis, MO, USA)</td>
			<td>7761-88-8</td>
			<td></td>
		</tr>
		<tr>
			<td>Graphite</td>
			<td>Sigma-Aldrich (St. Louis, MO, USA)</td>
			<td>7782-42-5</td>
			<td></td>
		</tr>
		<tr>
			<td>Sulfuric acid</td>
			<td>Sigma-Aldrich (St. Louis, MO, USA)</td>
			<td>7664-93-9</td>
			<td></td>
		</tr>
		<tr>
			<td>Phophoric acid</td>
			<td>Sigma-Aldrich (St. Louis, MO, USA)</td>
			<td>7664-38-2</td>
			<td></td>
		</tr>
		<tr>
			<td>Potassium permanganate</td>
			<td>Sigma-Aldrich (St. Louis, MO, USA)</td>
			<td>7722-64-7</td>
			<td></td>
		</tr>
		<tr>
			<td>Hydrogen peroxide</td>
			<td>JUNSEI</td>
			<td>23150-0350</td>
			<td></td>
		</tr>
		<tr>
			<td>Ammonium hydroxide</td>
			<td>Sigma-Aldrich (St. Louis, MO, USA)</td>
			<td>1336-21-6</td>
			<td></td>
		</tr>
		<tr>
			<td>Xe-lamp</td>
			<td>&#160;Cermax, Waltham, USA</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>NIR Laser</td>
			<td>Class-IV, Sanctity Laser, Shanghai, China&#160;</td>
			<td></td>
			<td>6W (output power)</td>
		</tr>
		<tr>
			<td>UV-Vis spectrophotometer&#160;</td>
			<td>S-3100, SINCO, South Korea</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Transmission Electron Microscopy</td>
			<td>H-7650, Hitachi, Japan</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Spectro Fluorometer</td>
			<td>Jasco FP-6500, Tokyo, Japan</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>X-ray Photoelectron Spectrometer</td>
			<td>AXIS&#8211;NOVA, KRATOS Inc., UK</td>
			<td></td>
			<td></td>
		</tr>
	</tbody>
</table>

visible-light induced reduction of graphene oxide using plasmonic nanoparticle

El presente trabajo demuestra la, y la energía método simple, libre de químicos, rápido eficiente para producir óxido de grafeno reducido (r-GO) solución a temperatura ambiente usando irradiación con luz visible con nanopartículas plasmónicas. La nanopartícula plasmónica se utiliza para mejorar la eficiencia de la reducción de GO. Sólo se tarda 30 min a TA mediante la iluminación de las soluciones con Xe-lámpara, las soluciones r-GO se pueden obtener mediante la eliminación total de las nanopartículas de oro por simple etapa de centrifugación. Las nanopartículas de oro esféricas (AuNPs) en comparación con las otras nanoestructuras es la nanoestructura plasmónica más adecuado para la preparación r-GO. El óxido de grafeno reducido preparado usando la luz visible y AuNPs fue igualmente cualitativa como reduce químicamente el óxido de grafeno, que fue apoyada por diversas técnicas analíticas como la espectroscopia UV-Vis, espectroscopia Raman, difracción de rayos X en polvo y XPS. El óxido de grafeno reducido preparado con luz visible muestra excelentes propiedades de enfriamiento sobre el fluormoléculas escent modificados en ssDNA y recuperación de fluorescencia excelente para la detección de ADN diana. Se encontró que la r-GO preparado por AuNPs reciclados para ser de la misma calidad con la de reducido químicamente r-GO. El uso de la luz visible con nanopartículas plasmónica demuestra el buen método alternativo para la síntesis de la r-GO.

La figura 1 muestra el esquema general para la luz visible y la reacción de reducción r-GO plasmónica de nanopartículas a base. La figura 2 muestra la configuración fundamental para las reacciones. Después de la reacción, se requiere la etapa de centrifugación para eliminar el fotocatalizador utilizado (AuNSs, AuNRs, o AuNPs) como se muestra en la Figura 3A. El análisis HRTEM muestra la eliminación completa de las nanopartículas en el sobrenadante (r-GO) <str...

Watch this Scientific Journal Video about Visible-light Induced Reduction of Graphene Oxide Using Plasmonic Nanoparticle at JoVE.com

Visible-light Induced Reduction of Graphene Oxide Using Plasmonic Nanoparticle

Un protocolo sencillo para la preparación de la reducción de óxido de grafeno usando luz visible y de nanopartículas plasmónica se describe.

Luz visible reducción inducida de grafeno Óxido Usando plasmónica de nanopartículas

Present work demonstrates the simple, chemical free, fast, and energy efficient method to produce reduced graphene oxide (r-GO) solution at RT using ...

visible-light-induced-reduction-graphene-oxide-using-plasmonic

Research

JoVE Journal

Engineering

14.3K vistas.  Korea University.  Un protocolo sencillo para la preparación de la reducción de óxido de grafeno usando luz visible y de nanopartículas plasmónica se describe. 

Video: Visible-light Induced Reduction of Graphene Oxide Using Plasmonic Nanoparticle

Design, Fabrication, and Experimental Characterization of Plasmonic Photoconductive Terahertz Emitters

In this video article we present a detailed demonstration of a highly efficient method for generating terahertz waves. Our technique is based on photoconduction, which has been one of the most commonly used techniques for terahertz generation 1-8. Terahertz generation in a photoconductive emitter is achieved by pumping an ultrafast photoconductor with a pulsed or heterodyned laser illumination. The induced photocurrent, which follows the envelope of the pump laser, is routed to a terahertz radiating antenna connected to the photoconductor contact electrodes to generate terahertz radiation. Although the quantum efficiency of a photoconductive emitter can theoretically reach 100%, the relatively long transport path lengths of photo-generated carriers to the contact electrodes of conventional photoconductors have severely limited their quantum efficiency. Additionally, the carrier screening effect and thermal breakdown strictly limit the maximum output power of conventional photoconductive terahertz sources. To address the quantum efficiency limitations of conventional photoconductive terahertz emitters, we have developed a new photoconductive emitter concept which incorporates a plasmonic contact electrode configuration to offer high quantum-efficiency and ultrafast operation simultaneously. By using nano-scale plasmonic contact electrodes, we significantly reduce the average photo-generated carrier transport path to photoconductor contact electrodes compared to conventional photoconductors 9. Our method also allows increasing photoconductor active area without a considerable increase in the capacitive loading to the antenna, boosting the maximum terahertz radiation power by preventing the carrier screening effect and thermal breakdown at high optical pump powers. By incorporating plasmonic contact electrodes, we demonstrate enhancing the optical-to-terahertz power conversion efficiency of a conventional photoconductive terahertz emitter by a factor of 50 10.

We describe methods for the design, fabrication, and experimental characterization of plasmonic photoconductive emitters, which offer two orders of magnitude higher terahertz power levels compared to conventional photoconductive emitters.

Diseño, Fabricación y Caracterización Experimental de Plasmónicos Emisores terahercios fotoconductoras

In this video article we present a detailed demonstration of a highly efficient method for generating terahertz waves. Our technique is based on ...

Investigación

Ingeniería

Evaluating Plasmonic Transport in Current-carrying Silver Nanowires

Plasmonics is an emerging technology capable of simultaneously transporting a plasmonic signal and an electronic signal on the same information support1,2,3. In this context, metal nanowires are especially desirable for realizing dense routing networks4. A prerequisite to operate such shared nanowire-based platform relies on our ability to electrically contact individual metal nanowires and efficiently excite surface plasmon polaritons5 in this information support. In this article, we describe a protocol to bring electrical terminals to chemically-synthesized silver nanowires6 randomly distributed on a glass substrate7. The positions of the nanowire ends with respect to predefined landmarks are precisely located using standard optical transmission microscopy before encapsulation in an electron-sensitive resist. Trenches representing the electrode layout are subsequently designed by electron-beam lithography. Metal electrodes are then fabricated by thermally evaporating a Cr/Au layer followed by a chemical lift-off. The contacted silver nanowires are finally transferred to a leakage radiation microscope for surface plasmon excitation and characterization8,9. Surface plasmons are launched in the nanowires by focusing a near infrared laser beam on a diffraction-limited spot overlapping one nanowire extremity5,9. For sufficiently large nanowires, the surface plasmon mode leaks into the glass substrate9,10. This leakage radiation is readily detected, imaged, and analyzed in the different conjugate planes in leakage radiation microscopy9,11. The electrical terminals do not affect the plasmon propagation. However, a current-induced morphological deterioration of the nanowire drastically degrades the flow of surface plasmons. The combination of surface plasmon leakage radiation microscopy with a simultaneous analysis of the nanowire electrical transport characteristics reveals the intrinsic limitations of such plasmonic circuitry.

Silver nanowires can simultaneously transport electrons and optical information in the form of surface plasmons. A procedure is described here to realize such a shared circuitry and the limitations at propagating both information carriers are evaluated.

Plasmonics is an emerging technology capable of simultaneously transporting a plasmonic signal and an electronic signal on the same information ...

Development of a 3D Graphene Electrode Dielectrophoretic Device

The design and fabrication of a novel 3D electrode microdevice using 50 &#181;m thick graphene paper and 100 &#181;m double sided tape is described. The protocol details the procedures to construct a versatile, reusable, multiple layer, laminated dielectrophoresis chamber. Specifically, six layers of 50 &#181;m x&#160;0.7 cm x&#160;2 cm graphene paper and five layers of double sided tape were alternately stacked together, then clamped to a glass slide. Then a 700 &#956;m diameter micro-well was drilled through the laminated structure using a computer-controlled micro drilling machine. Insulating properties of the tape layer between adjacent graphene layers were assured by resistance tests. Silver conductive epoxy connected alternate layers of graphene paper and formed stable connections between the graphene paper and external copper wire electrodes. The finished device was then clamped and sealed to a glass slide. The electric field gradient was modeled within the multi-layer device. Dielectrophoretic behaviors of 6 &#956;m polystyrene beads were demonstrated in the 1 mm deep micro-well, with medium conductivities ranging from 0.0001 S/m to 1.3 S/m, and applied signal frequencies from 100 Hz to 10 MHz. Negative dielectrophoretic responses were observed in three dimensions over most of the conductivity-frequency space and cross-over frequency values are consistent with previously reported literature values. The device did not prevent AC electroosmosis and electrothermal flows, which occurred in the low and high frequency regions, respectively. The graphene paper utilized in this device is versatile and could subsequently function as a biosensor after dielectrophoretic characterizations are complete.

A microdevice with high throughput potential is used to demonstrate three-dimensional (3D) dielectrophoresis (DEP) with novel materials. Graphene nanoplatelet paper and double sided tape were alternately stacked; a 700 &#956;m micro-well was drilled transverse to the layers. DEP behavior of polystyrene beads was demonstrated in the micro-well.

Desarrollo de un dispositivo 3D grafeno Electrodo dielectroforéticas

The design and fabrication of a novel 3D electrode microdevice using 50 &#181;m thick graphene paper and 100 &#181;m double sided tape is described. The ...

Writing and Low-Temperature Characterization of Oxide Nanostructures

Oxide nanoelectronics is a rapidly growing field which seeks to develop novel materials with multifunctional behavior at nanoscale dimensions. Oxide interfaces exhibit a wide range of properties that can be controlled include conduction, piezoelectric behavior, ferromagnetism, superconductivity and nonlinear optical properties. Recently, methods for controlling these properties at extreme nanoscale dimensions have been discovered and developed. Here are described explicit step-by-step procedures for creating LaAlO3/SrTiO3 nanostructures using a reversible conductive atomic force microscopy technique. The processing steps for creating electrical contacts to the LaAlO3/SrTiO3 interface are first described. Conductive nanostructures are created by applying voltages to a conductive atomic force microscope tip and locally switching the LaAlO3/SrTiO3 interface to a conductive state. A versatile nanolithography toolkit has been developed expressly for the purpose of controlling the atomic force microscope (AFM) tip path and voltage. Then, these nanostructures are placed in a cryostat and transport measurements are performed. The procedures described here should be useful to others wishing to conduct research in oxide nanoelectronics.

Oxide nanostructures provide new opportunities for science and technology. The interfacial conductivity between LaAlO3 and SrTiO3 can be controlled with near-atomic precision using a conductive atomic force microscopy technique. The protocol for creating and measuring conductive nanostructures at LaAlO3/SrTiO3 interfaces is demonstrated.

La escritura y la caracterización de baja temperatura de óxido de Nanoestructuras

Oxide nanoelectronics is a rapidly growing field which seeks to develop novel materials with multifunctional behavior at nanoscale dimensions.  Oxide ...

Synthesis and Functionalization of 3D Nano-graphene Materials: Graphene Aerogels and Graphene Macro Assemblies

Efforts to assemble graphene into three-dimensional monolithic structures have been hampered by the high cost and poor processability of graphene. Additionally, most reported graphene assemblies are held together through physical interactions (e.g., van der Waals forces) rather than chemical bonds, which limit their mechanical strength and conductivity. This video method details recently developed strategies to fabricate mass-producible, graphene-based bulk materials derived from either polymer foams or single layer graphene oxide. These materials consist primarily of individual graphene sheets connected through covalently bound carbon linkers. They maintain the favorable properties of graphene such as high surface area and high electrical and thermal conductivity, combined with tunable pore morphology and exceptional mechanical strength and elasticity. This flexible synthetic method can be extended to the fabrication of polymer/carbon nanotube (CNT) and polymer/graphene oxide (GO) composite materials. Furthermore, additional post-synthetic functionalization with anthraquinone is described, which enables a dramatic increase in charge storage performance in supercapacitor applications.

This video method describes the synthesis of high surface area, monolithic 3D graphene-based materials derived from polymer precursors as well as single layer graphene oxide.

Síntesis y funcionalización de 3D Materiales Nano-grafeno: grafeno aerogeles y grafeno Asambleas Macro

Efforts to assemble graphene into three-dimensional monolithic structures have been hampered by the high cost and poor processability of graphene. ...

Measurement of Scattering Nonlinearities from a Single Plasmonic Nanoparticle

Plasmonics, which are based on the collective oscillation of electrons due to light excitation, involve strongly enhanced local electric fields and thus have potential applications in nonlinear optics, which requires extraordinary optical intensity. One of the most studied nonlinearities in plasmonics is nonlinear absorption, including saturation and reverse saturation behaviors. Although scattering and absorption in nanoparticles are closely correlated by the Mie theory, there has been no report of nonlinearities in plasmonic scattering until very recently. 
Last year, not only saturation, but also reverse saturation of scattering in an isolated plasmonic particle was demonstrated for the first time. The results showed that saturable scattering exhibits clear wavelength dependence, which seems to be directly linked to the localized surface plasmon resonance (LSPR). Combined with the intensity-dependent measurements, the results suggest the possibility of a common mechanism underlying the nonlinear behaviors of scattering and absorption. These nonlinearities of scattering from a single gold nanosphere (GNS) are widely applicable, including in super-resolution microscopy and optical switches. 
In this paper, it is described in detail how to measure nonlinearity of scattering in a single GNP and how to employ the super-resolution technique to enhance the optical imaging resolution based on saturable scattering. This discovery features the first super-resolution microscopy based on nonlinear scattering, which is a novel non-bleaching contrast method that can achieve a resolution as low as l/8 and will potentially be useful in biomedicine and material studies.

Saturable and reverse saturable scattering were discovered in isolated plasmonic particles and adopted as a novel non-bleaching contrast method in super-resolution microscopy. Here the experimental procedures of detecting and extracting nonlinear scattering are explained in detail, as well as how to enhance resolution with the aid of saturated excitation microscopy.

La medición de la dispersión no linealidades de una nanopartícula Individual plasmónicas

Plasmonics, which are based on the collective oscillation of electrons due to light excitation, involve strongly enhanced local electric fields and thus ...

Iridium Oxide-reduced Graphene Oxide Nanohybrid Thin Film Modified Screen-printed Electrodes as Disposable Electrochemical Paper Microfluidic pH Sensors

A facile, controllable, inexpensive and green electrochemical synthesis of IrO2-graphene nanohybrid thin films is developed to fabricate an easy-to-use integrated paper microfluidic electrochemical pH sensor for resource-limited settings. Taking advantages from both pH meters and strips, the pH sensing platform is composed of hydrophobic barrier-patterned paper micropad (&#181;PAD) using polydimethylsiloxane (PDMS), screen-printed electrode (SPE) modified with IrO2-graphene films and molded acrylonitrile butadiene styrene (ABS) plastic holder. Repetitive cathodic potential cycling was employed for graphene oxide (GO) reduction which can completely remove electrochemically unstable oxygenated groups and generate a 2D defect-free homogeneous graphene thin film with excellent stability and electronic properties. A uniform and smooth IrO2 film in nanoscale grain size is anodically electrodeposited onto the graphene film, without any observable cracks. The resulting IrO2-RGO electrode showed slightly super-Nernstian responses from pH 2-12 in Britton-Robinson (B-R) buffers with good linearity, small hysteresis, low response time and reproducibility in different buffers, as well as low sensitivities to different interfering ionic species and dissolved oxygen. A simple portable digital pH meter is fabricated, whose signal is measured with a multimeter, using high input-impedance operational amplifier and consumer batteries. The pH values measured with the portable electrochemical paper-microfluidic pH sensors were consistent with those measured using a commercial laboratory pH meter with a glass electrode.

The study demonstrates the growth of iridium oxide-reduced graphene oxide (IrO2-RGO) nanohybrid thin films on irregular and rough screen-printed carbon substrate through a green electrochemical synthesis, and their implementation as a pH sensor with a patterned paper-fluidic platform.

Iridium grafeno óxido nanohíbrido Thin Film Modificados electrodos serigrafiados reducida de óxido-como Papel desechable de microfluidos electroquímico de pH Sensores

A facile, controllable, inexpensive and green electrochemical synthesis of IrO2-graphene nanohybrid thin films is developed to fabricate an easy-to-use ...

Preparation of ZnO Nanorod/Graphene/ZnO Nanorod Epitaxial Double Heterostructure for Piezoelectrical Nanogenerator by Using Preheating Hydrothermal

Well-aligned ZnO nanostructures have been intensively studied over the last decade for remarkable physical properties and enormous applications. Here, we describe a one-step fabrication technique to synthesis freestanding ZnO nanorod/graphene/ZnO nanorod double heterostructure. The preparation of the double heterostructure is performed by using thermal chemical vapor deposition (CVD) and preheating hydrothermal technique. In addition, the morphological properties were characterized by using the scanning electron microscopy (SEM). The utility of freestanding double heterostructure is demonstrated by fabricating the piezoelectric nanogenerator. The electrical output is improved up to 200% compared to that of a single heterostructure owing to the coupling effect of the piezoelectricity between the arrays of ZnO nanorods on the top and bottom of graphene. This unique double heterostructure have a tremendous potential for applications of electrical and optoelectrical devices where the high number density and specific surface area of nanorod are needed, such as pressure sensor, immuno-biosensor and dye-sensitized solar cells.

One-step fabrication method for obtaining freestanding epitaxial double heterostructure is presented. This approach could achieve ZnO coverage with a higher number density than that of the epitaxial single heterostructure, leading to a piezoelectric nanogenerator with an increased output electrical performance.

Preparación de ZnO nanorod / grafeno / ZnO nanorod epitaxialLa heteroestructura doble para piezoeléctricas nanogenerador mediante precalentamiento Hidrotermal

Well-aligned ZnO nanostructures have been intensively studied over the last decade for remarkable physical properties and enormous applications. Here, we ...

Multifunctional Hybrid Fe2O3-Au Nanoparticles for Efficient Plasmonic Heating

One of the most widely used methods for manufacturing colloidal gold nanospherical particles involves the reduction of chloroauric acid (HAuCl4) to neutral gold Au(0) by reducing agents, such as sodium citrate or sodium borohydride. The extension of this method to decorate iron oxide or similar nanoparticles with gold nanoparticles to create multifunctional hybrid Fe2O3-Au nanoparticles is straightforward. This approach yields fairly good control over Au nanoparticle dimensions and loading onto Fe2O3. Additionally, the Au metal size, shape, and loading can easily be tuned by changing experimental parameters (e.g., reactant concentrations, reducing agents, surfactants, etc.). An advantage of this procedure is that the reaction can be done in air or water, and, in principle, is amenable to scaling up. The use of such optically tunable Fe2O3-Au nanoparticles for hyperthermia studies is an attractive option as it capitalizes on plasmonic heating of gold nanoparticles tuned to absorb light strongly in the VIS-NIR region. In addition to its plasmonic effects, nanoscale Au provides a unique surface for interesting chemistries and catalysis. The Fe2O3 material provides additional functionality due to its magnetic property. For example, an external magnetic field could be used to collect and recycle the hybrid Fe2O3-Au nanoparticles after a catalytic experiment, or alternatively, the magnetic Fe2O3 can be used for hyperthermia studies through magnetic heat induction. The photothermal experiment described in this report measures bulk temperature change and nanoparticle solution mass loss as functions of time using infrared thermocouples and a balance, respectively. The ease of sample preparation and the use of readily available equipment are distinct advantages of this technique. A caveat is that these photothermal measurements assess the bulk solution temperature and not the surface of the nanoparticle where the heat is transduced and the temperature is likely to be higher.

Multifunctional Hybrid Fe2O3-Au Nanoparticles for Efficient Plasmonic Heating

We describe the synthesis and properties of multifunctional Fe2O3-Au nanoparticles produced by a wet chemical approach and investigate their photothermal properties using laser irradiation. The composite Fe2O3-Au nanoparticles retain the properties of both materials, creating a multifunctional structure with excellent magnetic and plasmonic properties.

Multifuncional híbrido Fe<sub&gt; 2</sub&gt; O<sub&gt; 3</sub&gt; -Au Nanopartículas para la calefacción eficiente plasmónicas

One of the most widely used methods for manufacturing colloidal gold nanospherical particles involves the reduction of chloroauric acid (HAuCl4) to ...

Advanced Compositional Analysis of Nanoparticle-polymer Composites Using Direct Fluorescence Imaging

The fabrication of polymer-nanoparticle composites is extremely important in the development of many functional materials. Identifying the precise composition of these materials is essential, especially in the design of surface catalysts, where the surface concentration of the active component determines the activity of the material. Antimicrobial materials which utilize nanoparticles are a particular focus of this technology. Recently swell encapsulation has emerged as a technique for inserting antimicrobial nanoparticles into a host polymer matrix. Swell encapsulation provides the advantage of localizing the incorporation to the external surfaces of materials, which act as the active sites of these materials. However, quantification of this nanoparticle uptake is challenging. Previous studies explore the link between antimicrobial activity and surface concentration of the active component, but this is not directly visualized. Here we show a reliable method to monitor the incorporation of nanoparticles into a polymer host matrix via swell encapsulation. We show that the surface concentration of CdSe/ZnS nanoparticles can be accurately visualized through cross-sectional fluorescence imaging. Using this method, we can quantify the uptake of nanoparticles via swell encapsulation and measure the surface concentration of encapsulated particles, which is key in optimizing the activity of functional materials.

Here we present a reliable method to monitor the incorporation of nanoparticles into a polymer host matrix via swell encapsulation. We show that the surface concentration of cadmium selenide quantum dots can be accurately visualized through cross-sectional fluorescence imaging.