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>

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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><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&amp;#160;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>&amp;nbsp;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 (&amp;ge;99%)</td><td>Sigma-Aldrich (St. Louis, MO, USA)</td><td>57-09-0</td><td></td></tr><tr><td>L-Ascorbic Acid(&amp;ge;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&amp;nbsp; (&amp;ge;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>&amp;nbsp;Cermax, Waltham, USA</td><td></td><td></td></tr><tr><td>NIR Laser</td><td>Class-IV, Sanctity Laser, Shanghai, China&amp;nbsp;</td><td></td><td>6W (output power)</td></tr><tr><td>UV-Vis spectrophotometer&amp;nbsp;</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&amp;ndash;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

Universidad de Cartagena UDEC

Research

JoVE Journal

Engineering

14.4K 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

Template Directed Synthesis of Plasmonic Gold Nanotubes with Tunable IR Absorbance

A nearly parallel array of pores can be produced by anodizing aluminum foils in acidic environments1, 2. Applications of anodic aluminum oxide (AAO) membranes have been under development since the 1990's and have become a common method to template the synthesis of high aspect ratio nanostructures, mostly by electrochemical growth or pore-wetting. Recently, these membranes have become commercially available in a wide range of pore sizes and densities, leading to an extensive library of functional nanostructures being synthesized from AAO membranes. These include composite nanorods, nanowires and nanotubes made of metals, inorganic materials or polymers 3-10. Nanoporous membranes have been used to synthesize nanoparticle and nanotube arrays that perform well as refractive index sensors, plasmonic biosensors, or surface enhanced Raman spectroscopy (SERS) substrates 11-16, as well as a wide range of other fields such as photo-thermal heating 17, permselective transport 18, 19, catalysis 20, microfluidics 21, and electrochemical sensing 22, 23. Here, we report a novel procedure to prepare gold nanotubes in AAO membranes. Hollow nanostructures have potential application in plasmonic and SERS sensing, and we anticipate these gold nanotubes will allow for high sensitivity and strong plasmon signals, arising from decreased material dampening 15.

Solution-suspendable gold nanotubes with controlled dimensions can be synthesized by electrochemical deposition in porous anodic aluminum oxide (AAO) membranes using a hydrophobic polymer core. Gold nanotubes and nanotube arrays hold promise for applications in plasmonic biosensing, surface-enhanced Raman spectroscopy, photo-thermal heating, ionic and molecular transport, microfluidics, catalysis and electrochemical sensing.

Plantilla Dirigida Síntesis de nanotubos de oro plasmónicos con Tunable absorbancia IR

A nearly parallel array of pores can be produced by anodizing aluminum foils in acidic environments1, 2. Applications of anodic aluminum oxide (AAO) ...

Investigación

Química

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 ...

Ingeniería

Utilization of Plasmonic and Photonic Crystal Nanostructures for Enhanced Micro- and Nanoparticle Manipulation

A method to manipulate the position and orientation of submicron particles nondestructively would be an incredibly useful tool for basic biological research. Perhaps the most widely used physical force to achieve noninvasive manipulation of small particles has been dielectrophoresis(DEP).1 However, DEP on its own lacks the versatility and precision that are desired when manipulating cells since it is traditionally done with stationary electrodes. Optical tweezers, which utilize a three dimensional electromagnetic field gradient to exert forces on small particles, achieve this desired versatility and precision.2 However, a major drawback of this approach is the high radiation intensity required to achieve the necessary force to trap a particle which can damage biological samples.3 A solution that allows trapping and sorting with lower optical intensities are optoelectronic tweezers (OET) but OET's have limitations with fine manipulation of small particles; being DEP-based technology also puts constraint on the property of the solution.4,5
This video article will describe two methods that decrease the intensity of the radiation needed for optical manipulation of living cells and also describe a method for orientation control. The first method is plasmonic tweezers which use a random gold nanoparticle (AuNP) array as a substrate for the sample as shown in Figure 1. The AuNP array converts the incident photons into localized surface plasmons (LSP) which consist of resonant dipole moments that radiate and generate a patterned radiation field with a large gradient in the cell solution. Initial work on surface plasmon enhanced trapping by Righini et al and our own modeling have shown the fields generated by the plasmonic substrate reduce the initial intensity required by enhancing the gradient field that traps the particle.6,7,8 The plasmonic approach allows for fine orientation control of ellipsoidal particles and cells with low optical intensities because of more efficient optical energy conversion into mechanical energy and a dipole-dependent radiation field. These fields are shown in figure 2 and the low trapping intensities are detailed in figures 4 and 5. The main problems with plasmonic tweezers are that the LSP's generate a considerable amount of heat and the trapping is only two dimensional. This heat generates convective flows and thermophoresis which can be powerful enough to expel submicron particles from the trap.9,10 The second approach that we will describe is utilizing periodic dielectric nanostructures to scatter incident light very efficiently into diffraction modes, as shown in figure 6.11 Ideally, one would make this structure out of a dielectric material to avoid the same heating problems experienced with the plasmonic tweezers but in our approach an aluminum-coated diffraction grating is used as a one-dimensional periodic dielectric nanostructure. Although it is not a semiconductor, it did not experience significant heating and effectively trapped small particles with low trapping intensities, as shown in figure 7. Alignment of particles with the grating substrate conceptually validates the proposition that a 2-D photonic crystal could allow precise rotation of non-spherical micron sized particles.10 The efficiencies of these optical traps are increased due to the enhanced fields produced by the nanostructures described in this paper.

Plasmonic tweezers and photonic crystal nanostructures are shown to produce useful enhancements in the efficiency and orientation control of optically trapping micro- and nano-particles.

Utilización de nanoestructuras fotónicas de cristal plasmónicos y para la manipulación mejorada de Micro y nanopartículas

A method to manipulate the position and orientation of submicron particles nondestructively would be an incredibly useful tool for basic biological ...

Bioingeniería

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 ...

In Situ Synthesis of Gold Nanoparticles without Aggregation in the Interlayer Space of Layered Titanate Transparent Films

Combinations of metal oxide semiconductors and gold nanoparticles (AuNPs) have been investigated as new types of materials. The in situ synthesis of AuNPs within the interlayer space of semiconducting layered titania nanosheet (TNS) films was investigated here. Two types of intermediate films (i.e., TNS films containing methyl viologen (TNS/MV2+) and 2-ammoniumethanethiol (TNS/2-AET+)) were prepared. The two intermediate films were soaked in an aqueous tetrachloroauric(III) acid (HAuCl4) solution, whereby considerable amounts of Au(III) species were accommodated within the interlayer spaces of the TNS films. The two types of obtained films were then soaked in an aqueous sodium tetrahydroborate (NaBH4) solution, whereupon the color of the films immediately changed from colorless to purple, suggesting the formation of AuNPs within the TNS interlayer. When only TNS/MV2+ was used as the intermediate film, the color of the film gradually changed from metallic purple to dusty purple within 30 min, suggesting that aggregation of AuNPs had occurred. In contrast, this color change was suppressed by using the TNS/2-AET+ intermediate film, and the AuNPs were stabilized for over 4 months, as evidenced by the characteristic extinction (absorption and scattering) band from the AuNPs.

In Situ Synthesis of Gold Nanoparticles without Aggregation in the Interlayer Space of Layered Titanate Transparent Films

Here, we present a protocol for the in situ synthesis of gold nanoparticles (AuNPs) within the interlayer space of layered titanate films without the aggregation of AuNPs. No spectral change was observed even after 4 months. The synthesized material has expected applications in catalysis, photo-catalysis, and the development of cost-effective plasmonic devices.

In Situ Síntesis de nanopartículas de oro sin agregación en el espacio entre capas de Capas de titanato películas transparentes

Combinations of metal oxide semiconductors and gold nanoparticles (AuNPs) have been investigated as new types of materials. The in situ synthesis of AuNPs ...

Fabrication of Periodic Gold Nanocup Arrays Using Colloidal Lithography

Within recent years, the field of plasmonics has exploded as researchers have demonstrated exciting applications related to chemical and optical sensing in combination with new nanofabrication techniques. A plasmon is a quantum of charge density oscillation that lends nanoscale metals such as gold and silver unique optical properties. In particular, gold and silver nanoparticles exhibit localized surface plasmon resonances-collective charge density oscillations on the surface of the nanoparticle-in the visible spectrum. Here, we focus on the fabrication of periodic arrays of anisotropic plasmonic nanostructures. These half-shell (or nanocup) structures can exhibit additional unique light-bending and polarization-dependent optical properties that simple isotropic nanostructures cannot. Researchers are interested in the fabrication of periodic arrays of nanocups for a wide variety of applications such as low-cost optical devices, surface-enhanced Raman scattering, and tamper indication. We present a scalable technique based on colloidal lithography in which it is possible to easily fabricate large periodic arrays of nanocups using spin-coating and self-assembled commercially available polymeric nanospheres. Electron microscopy and optical spectroscopy from the visible to near-infrared (near-IR) was performed to confirm successful nanocup fabrication. We conclude with a demonstration of the transfer of nanocups to a flexible, conformal adhesive film.

We demonstrate the fabrication of periodic gold nanocup arrays using colloidal lithographic techniques and discuss the importance of nanoplasmonic films.

Fabricación de matrices Nanocup oro periódicas usando litografía coloidal

Within recent years, the field of plasmonics has exploded as researchers have demonstrated exciting applications related to chemical and optical sensing ...

Determination of the Excitation and Coupling Rates Between Light Emitters and Surface Plasmon Polaritons

We have developed a unique method to measure the excitation and coupling rates between the light emitters and surface plasmon polaritons (SPPs) arising from metallic periodic arrays without involving time-resolved techniques. We have formulated the rates by quantities that can be measured by simple optical measurements. The instrumentation based on angle- and polarization-resolved reflectivity and photoluminescence spectroscopy will be described in detail here. Our approach is intriguing due to its simplicity, which requires routine optics and several mechanical stages, and thus is highly affordable to most of the research laboratories.

This protocol describes the instrumentation for determining the excitation and coupling rates between light emitters and Bloch-like surface plasmon polaritons arising from periodic arrays.

Determinación de la excitación y el acoplamiento entre emisores de luz y plasmón superficial Polaritons

We have developed a unique method to measure the excitation and coupling rates between the light emitters and surface plasmon polaritons (SPPs) arising ...

Performing Spectroscopy on Plasmonic Nanoparticles with Transmission-Based Nomarski-Type Differential Interference Contrast Microscopy

Differential interference contrast (DIC) microscopy is a powerful imaging tool that is most commonly employed for imaging microscale objects using visible-range light. The purpose of this protocol is to detail a proven method for preparing plasmonic nanoparticle samples and performing single particle spectroscopy on them with DIC microscopy. Several important steps must be followed carefully in order to perform repeatable spectroscopy experiments. First, landmarks can be etched into the sample substrate, which aids in locating the sample surface and in tracking the region of interest during experiments. Next, the substrate must be properly cleaned of debris and contaminants that can otherwise hinder or obscure examination of the sample. Once a sample is properly prepared, the optical path of the microscope must be aligned, using Kohler Illumination. With a standard Nomarski style DIC microscope, rotation of the sample may be necessary, particularly when the plasmonic nanoparticles exhibit orientation-dependent optical properties. Because DIC microscopy has two inherent orthogonal polarization fields, the wavelength-dependent DIC contrast pattern reveals the orientation of rod-shaped plasmonic nanoparticles. Finally, data acquisition and data analyses must be carefully performed. It is common to represent DIC-based spectroscopy data as a contrast value, but it is also possible to present it as intensity data. In this demonstration of DIC for single particle spectroscopy, the focus is on spherical and rod-shaped gold nanoparticles.

The goal of this protocol is to detail a proven approach for the preparation of plasmonic nanoparticle samples and for performing single particle spectroscopy on them with differential interference contrast (DIC) microscopy.

Realización de espectroscopía en nanopartículas Plasmónicas con microscopía de contraste de interferencia diferencial de tipo Nomarski basado en la transmisión

Differential interference contrast (DIC) microscopy is a powerful imaging tool that is most commonly employed for imaging microscale objects using ...

Photodeposition of Pd onto Colloidal Au Nanorods by Surface Plasmon Excitation

A protocol is described to photocatalytically guide Pd deposition onto Au nanorods (AuNR) using surface plasmon resonance (SPR). Excited plasmonic hot electrons upon SPR irradiation drive reductive deposition of Pd on colloidal AuNR in the presence of [PdCl4]2-. Plasmon-driven reduction of secondary metals potentiates covalent, sub-wavelength deposition at targeted locations coinciding with electric field &#8220;hot-spots&#8221; of the plasmonic substrate using an external field (e.g., laser). The process described herein details a solution-phase deposition of a catalytically-active noble metal (Pd) from a transition metal halide salt (H2PdCl4) onto aqueously-suspended, anisotropic plasmonic structures (AuNR). The solution-phase process is amenable to making other bimetallic architectures. Transmission UV-vis monitoring of the photochemical reaction, coupled with ex situ XPS and statistical TEM analysis, provide immediate experimental feedback to evaluate properties of the bimetallic structures as they evolve during the photocatalytic reaction. Resonant plasmon irradiation of AuNR in the presence of [PdCl4]2- creates a thin, covalently-bound Pd0 shell without any significant dampening effect on its plasmonic behavior in this representative experiment/batch. Overall, plasmonic photodeposition offers an alternative route for high-volume, economical synthesis of optoelectronic materials with sub-5 nm features (e.g., heterometallic photocatalysts or optoelectronic interconnects).

A protocol for anisotropic photodeposition of Pd onto aqueously-suspended Au nanorods via localized surface plasmon excitation is presented.

Fotodeposición de Pd en Colloidal Au Nanorods por Surface Plasmon Excitation

A protocol is described to photocatalytically guide Pd deposition onto Au nanorods (AuNR) using surface plasmon resonance (SPR). Excited plasmonic hot ...

Graphene-Assisted Quasi-van der Waals Epitaxy of AlN Film on Nano-Patterned Sapphire Substrate for Ultraviolet Light Emitting Diodes

This protocol demonstrates a method for graphene-assisted quick growth and coalescence of AlN on nano-pattened sapphire substrate (NPSS). Graphene layers are directly grown on NPSS using catalyst-free atmospheric-pressure chemical vapor deposition (APCVD). By applying nitrogen reactive ion etching (RIE) plasma treatment, defects are introduced into the graphene film to enhance chemical reactivity. During metal-organic chemical vapor deposition (MOCVD) growth of AlN, this N-plasma treated graphene buffer enables AlN quick growth, and coalescence on NPSS is confirmed by cross-sectional scanning electron microscopy (SEM). The high quality of AlN on graphene-NPSS is then evaluated by X-ray rocking curves (XRCs) with narrow (0002) and (10-12) full width at half-maximum (FWHM) as 267.2 arcsec and 503.4 arcsec, respectively. Compared to bare NPSS, AlN growth on graphene-NPSS shows significant reduction of residual stress from 0.87 GPa to 0.25 Gpa, based on Raman measurements. Followed by AlGaN multiple quantum wells (MQWS) growth on graphene-NPSS, AlGaN-based deep ultraviolet light-emitting-diodes (DUV LEDs) are fabricated. The fabricated DUV-LEDs also demonstrate obvious, enhanced luminescence performance. This work provides a new solution for the growth of high quality AlN and fabrication of high performance DUV-LEDs using a shorter process and less costs.

A protocol for graphene-assisted growth of high-quality AlN films on nano-patterned sapphire substrate is presented.

Cuasi-van der Waals asistida por grafeno epitaxy de película alN sobre sustrato de zafiro nano-patrón para diodos emisores de luz ultravioleta

This protocol demonstrates a method for graphene-assisted quick growth and coalescence of AlN on nano-pattened sapphire substrate (NPSS). Graphene layers ...