Name: fabrication of periodic gold nanocup arrays using colloidal lithography
Uploaded: 2017-09-02T13:00:00.000+00:00
Duration: 8 min 21 s
Description: Watch this Scientific Journal Video about Fabrication of Periodic Gold Nanocup Arrays Using Colloidal Lithography at JoVE.com

Esta investigación fue realizada en el laboratorio nacional del Noroeste Pacífico (PNNL), que es funcionada por Battelle Memorial Institute para el Departamento de energía (DOE) bajo contrato no. DE-AC05-76RL01830. Los autores agradece apoyo del Departamento de estado de Estados Unidos a través de la clave de verificación activos fondo (V) bajo SIAA15AVCVPO10 de acuerdo interinstitucional.

1. preparación de material <ol><li>coloque varias obleas de silicio de 2 pulgadas en un portador de cuarzo para limpiar y cargar las obleas de silicio en el sistema de grabado de plasma. La cámara de vacío la bomba hacia abajo hasta alcanzar al menos 75 mTorr. Esto puede tardar unos minutos.</li>
	<li>Comenzar el flujo de O 2 (30 sccm) gas y permitir que la presión se estabilice. Configurar el tiempo de etch a 15 min. Una vez se haya estabilizado la presión iniciar el plasma de radiofrecuencia (RF) 13.56 MHz 250 W. 
	Nota: Este paso limpia las obleas de silicio de cualquier materia orgánica contamina y functionalizes la superficie con hidroxilados (-OH) garantizando una superficie hidrofílica grupos.</li>
	<li>Mientras espera para la limpieza del plasma paso para terminar, sacar las nanoesferas poliestireno comercialmente compradas (170 nm de diámetro, 10% de sólidos, dodecil sulfato de sodio de 0,5%) de la nevera (4 ° C). Deje el recipiente a temperatura ambiente.</li>
	<li>Brevemente vortex (1 min) y someter a ultrasonidos (35 kHz, 1 min) las nanoesferas poliestireno para minimizar la aglomeración de nanosphere.</li>
	<li>En un frasco de vidrio limpio, medir 1.0 mL de las nanoesferas poliestireno de 170 nm y añada 1,0 mL de H 2 O para obtener una suspensión coloidal 5% de sólidos.</li>
	<li>Después de 15 minutos, detenga el flujo de O 2, ventilar la cámara de vacío y retirar las obleas recién limpiadas.</li>
</ol> 2. Spin-coating de plantilla de nanoesferas de poliestireno <ol><li>descarga el silicio limpiar obleas del desbastador de plasma. Luego le Monte una oblea de 2 pulgadas en un recubridor de vuelta. Asegúrese de que quede centrada correctamente y que la junta tórica esté libre de cualquier escombro. Iniciar el vacío y asegúrese de que la oblea esté fijada firmemente a la etapa de.</li>
	<li>Configurar los parámetros de vuelta de la máquina de pintar del spin. Estos parámetros varían según el tamaño de nanosphere. Para una solución de 5% 170 nm nanoesferas, establece un recubridor spin en un proceso del 1 paso con un tiempo de vuelta de 1 minuto, una velocidad de 3.000 rpm y una aceleración de 2.000 rpm/s.</li>
	<li>Usando una jeringuilla disponible, retirar ~ 1 mL de suspensión coloidal del frasco. Dejar reposar el frasco. Tomar un filtro de jeringa 5 μm y coloque en el extremo de la jeringa. Presionar la jeringa hasta que una gota de la suspensión pasa por la punta. El filtro elimina indeseables agregados y partículas que puede reducir significativamente la calidad de la película.</li>
	<li>Depositar suficiente suspensión directamente en el centro de la oblea que aproximadamente 2/3 de la superficie está cubierta. Tratar de minimizar las burbujas porque los pueden afectar la calidad de la película. Cierre la tapa del recubridor spin y presione Start. Durante este proceso, es posible ver efectos de interferencia de película delgada en la superficie de la oblea como las nanoesferas uno mismo-montar. Esto variará según el diámetro de nanosphere.</li>
	<li>Quitar la oblea recubierta de vuelta después de desactivar el vacío. Limpie el recipiente y la tapa de la spin coater para quitar exceso nanoesferas.</li>
</ol> 3. Evaluación de la calidad y preparación para grabado de cine <ol><li>evaluar visualmente la calidad de la película uno mismo-montado buscando notables defectos como rayas o agujeros que pueden haber sido causados por partículas durante el proceso de spin-coating.</li>
	<li>Evaluar la calidad de la película mediante la colocación de la oblea debajo de un microscopio óptico. Límites de grano y algunos defectos son normales. Si la oblea tiene grandes áreas sin recubrimiento o multicapas obvio, es necesario ajustar los parámetros de giro para obtener una película más uniforme. La microscopia electrónica puede usarse también para evaluar la calidad de la película.</li>
	<li>Encender la fuente de luz del microscopio y en la superficie de la oblea de silicio con objetivo 20 X. Evaluar la calidad en varios puntos a lo largo de la oblea para asegurar uniformidad.</li>
	<li>La calidad final de la película comprobar es utilizar microscopía electrónica (SEM) para visualizar la nanoesfera uno mismo-montaje a escala nanométrica. Es posible evaluar el grado de multicapas, agujeros y defectos/límites de grano a través de pequeñas porciones de la oblea relativamente rápidamente utilizando esta técnica.</li>
	<li>Una vez obtenida una cantidad suficiente de película, colocar la oblea en un horno (107 ° C) durante 2 min a templar las nanoesferas uno mismo-montado. Esto ayuda a fomentar la adherencia al sustrato y produce una mejor superficie de nanopatterned después del grabado.</li>
</ol> 4. Aguafuerte, Metal deposición y caracterización óptica <ol><li>cargar la oblea del recocido en el desbastador de plasma e iniciar el proceso de vaciado.</li>
	<li>Una vez que la cámara de vacío alcanza por lo menos 75 mTorr, comenzar el flujo de O 2 (20 sccm) gas y esperar a que la presión se estabilice. Iniciar el plasma RF (75 W) para 165 s.</li>
	<li>Una vez que ha completado el ciclo de plasma RF, detener el flujo de O 2 y la cámara de ventilación.</li>
	<li>El sustrato ya está grabado y listo para el depósito de metal. Transportar la muestra a un recubridor sputter y depositan un fino (20 nm) capa de oro. Diferentes ángulos de deposición pueden utilizarse para modificar las propiedades ópticas de la nanocups. En este caso, se llevó a cabo metal deposición normalmente incidente al sustrato.</li>
	<li>Después de la deposición del metal, el sustrato puede caracterizarse mediante espectroscopía óptica. Enfocar la microspectrophotometer sobre la superficie del sustrato metalizado y medir los espectros de reflectancia. Para 170 nm grabado arreglos de nanosphere, el LSPR fue a 615 nm.</li>
	<li>Con cinta de adhesiva sensible a la presión, coloque con cuidado la película en contacto con el sustrato. Puede ser necesario eliminar cualquier burbuja de aire formada en el interfaz de uso de unas pinzas.</li>
	<li>Una vez que la cinta esté en contacto con el sustrato, la cinta puede ser inmediatamente pelada para eliminar la nanocups de la superficie del sustrato. Suavemente la cáscara detrás la cinta y el resultado es una película flexible y conformal de oro nanocups.</li>
</ol>

<ol>
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M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Electron-beam+lithography+of+plasmonic+nanorod+arrays+for+multilayered+optical+storage.">Electron-beam lithography of plasmonic nanorod arrays for multilayered optical storage.</a> Optics Express. 22 (11), 13234-13243 (2014).</li><li>Endo, H., Mochizuki, Y., Tamura, M., Kawai, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fabrication+and+Functionalization+of+Periodically+Aligned+Metallic+Nanocup+Arrays+Using+Colloidal+Lithography+with+a+Sinusoidally+Wrinkled+Substrate.">Fabrication and Functionalization of Periodically Aligned Metallic Nanocup Arrays Using Colloidal Lithography with a Sinusoidally Wrinkled Substrate.</a> Langmuir. 29 (48), 15058-15064 (2013).</li><li>Wang, H., 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=Symmetry+breaking+in+individual+plasmonic+nanoparticles.">Symmetry breaking in individual plasmonic nanoparticles.</a> Proceedings of the National Academy of Sciences. 103 (29), 10856-10860 (2006).</li><li>Wollet, L., 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=Plasmon+hybridization+in+stacked+metallic+nanocups.">Plasmon hybridization in stacked metallic nanocups.</a> Optical Materials Express. 2 (10), 1384-1390 (2012).</li><li>Duempelmann, L., Casari, D., Luu-Dinh, A., Gallinet, B., Novotny, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Color+Rendering+Plasmonic+Aluminum+Substrates+with+Angular+Symmetry+Breaking.">Color Rendering Plasmonic Aluminum Substrates with Angular Symmetry Breaking.</a> ACS Nano. 9 (12), 12383-12391 (2015).</li><li>King, N. 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Los autores no tienen nada que revelar.

Este protocolo muestra una técnica eficiente y de bajo costo para la fabricación de arreglos periódicos de plasmónica nanocups oro. Esta técnica es particularmente ventajosa porque evita serie procesos de arriba hacia abajo como la litografía por haz de electrones o viga de ion enfocada de fresado. La técnica presentada muestra que nanoesferas poliméricos disponibles comercialmente pueden uno mismo-montarse de forma sencilla para servir como una plantilla de tamaño nanométrico para su posterior procesamiento.</...

La aparición de la plasmónica junto con mejorado nanofabricación y técnicas de síntesis han dado lugar a una gran variedad de emocionantes tecnologías tales como secundario-difracción limitada circuitería mejorada Detección química ysensor óptico 1 ,2,3. En este protocolo, se demuestra una técnica escalable y relativamente de bajo costo capaz de la fabricación de sustratos plasmónica nanopatterned usando nanoesferas poliméricos disponibles en el mercado y un paso de grabado seguido por la deposición de metal. A diferencia de otras técnicas para la fabricación de sustratos nanopatterned, tal como electrón viga litografía4, esta técnica puede rápidamente y eficientemente ser escalada a obleas de 300 mm y más allá con un mínimo esfuerzo y utiliza una transferencia paso para producir flexible y conformación de películas5.
Desde la época romana, sabemos que ciertos metales como el oro y la plata pueden tener propiedades ópticas brillantes cuando están finamente divididos. Hoy en día, entendemos que estas partículas metálicas exhiben un efecto llamado el "resonancia de plasmón superficial localizada" (LSPR) cuando sus dimensiones aproximan a la nanoescala. LSPR es análogo a una onda en la cual electrones débilmente enlazados encontradas el metal oscilan coherente cuando las partículas de metal ilumina la luz de ciertas frecuencias. Anisotropic nanoestructuras son de particular interés debido a resonancias ópticas únicas pueden surgir como resultado de la simetría rompe6,7,8.
La iluminación de estructuras de media concha (nanocup) con luz puede excitar dipolo eléctrico o magnético Dipolo plasmon modos, dependiendo de factores como el ángulo de deposición del metal, la orientación del sustrato con respecto a la luz del incidente y el polarización de la luz incidente9. Nanocups a menudo se han considerado análogos a tridimensionales arillo resonadores, en el que la frecuencia de resonancia se puede aproximadas como un oscilador LC10,11. La frecuencia de resonancia para el tamaño de nanoesferas poliméricos utilizados aquí (170 nm), la cantidad de oro depositada (20 nm), y las tarifas de etch frecuencias de resonancia que abarca lo visible y cerca-IR.
Las propiedades ópticas de la nanocups oro pueden medirse ya sea en la transmisión o reflexión, dependiendo del sustrato utilizado por spin-coating. En el protocolo presentado, decidimos utilizar las obleas de silicio de 2 pulgadas como el substrato y realizar mediciones de reflectancia después de deposición de metal. Las mediciones se realizaron utilizando un microscopio acoplado a un espectrómetro dispersivo con una fuente de luz halógena. También hemos tenido éxito con el uso de substratos de vidrio, lo que permite la transmisión y reflexión las mediciones inmediatamente después de la deposición de metal. Además, esta técnica puede escalarse fácilmente y no se limita a las obleas de 2 pulg. Debido a la disponibilidad amplia comercial de nanoesferas polímeros monodispersos de alta calidad, es muy fácil sintonizar las propiedades ópticas de estas estructuras simplemente iniciando con nanoesferas de diferentes tamaños.
En el presente Protocolo, una técnica para fabricar anisotrópico oro media concha (o nanocup) nanoestructuras utilizando un método llamado litografía coloidal está demostrado. Litografía coloidal usa autoensamblaje de altamente monodispersa nanosphere poliméricos para patrón rápidamente un sustrato que puede ser procesado en un sustrato plasmónica después de Farfullar revestimiento una fina capa de oro. Asimismo, es posible sintonizar la anisotropía del sustrato por la inclinación del sustrato de la muestra durante la deposición de metal. Las estructuras resultantes son sensibles a la polarización debido a la anisotropía de la nanoestructura formada. Aquí, demostramos una particular del caso y realizar la caracterización óptica y despegue para transferir las estructuras a una película transparente y flexible.

<table><tbody><tr><td>Polystyrene microspheres</td><td>Bangs Laboratories, Inc.</td><td>PS02N</td><td>170 nm &amp;ndash; 580 nm diameter</td></tr><tr><td>Silicon wafers</td><td>El-CAT, Inc.</td><td>3489</td><td>300 mm thick, one side polished [100]</td></tr><tr><td>Adhesive tape</td><td>3M</td><td>Scotch 600</td><td></td></tr><tr><td>Spin coater</td><td>Laurell</td><td>WS-650-23B</td><td></td></tr><tr><td>Plasma etcher</td><td>Nordson March&amp;nbsp;</td><td>AP-600</td><td></td></tr><tr><td>Microspectrophotometer</td><td>CRAIC</td><td>380-PV</td><td></td></tr><tr><td>Sonicator</td><td>VWR</td><td>97043-932</td><td></td></tr><tr><td>Scintillation vials</td><td>Wheaton</td><td>986734</td><td></td></tr><tr><td>5 um syringe filter</td><td>Millex</td><td>SLSV025LS</td><td></td></tr><tr><td>Oxygen gas</td><td>Oxarc</td><td>PO249&amp;nbsp;</td><td>Industrial Grade 99.5% purity</td></tr><tr><td>Vaccum pump</td><td>Kurt J. Lesker</td><td>Edwards 28</td><td></td></tr><tr><td>Disposable syringes</td><td>Air Tite Products Co.</td><td>14-817-25</td><td>1 mL capacity</td></tr><tr><td>Water</td><td>Sigma-Aldrich</td><td>W4502</td><td></td></tr></tbody></table>

fabrication of periodic gold nanocup arrays using colloidal lithography

Dentro de estos últimos años, el campo de la plasmónica ha explotado como los investigadores han demostrado interesantes aplicaciones relacionadas a los sensores ópticos y químicos en combinación con las nuevas técnicas de nanofabricación. Un plasmón es un quantum de oscilación de la densidad de la carga que se presta a nanoescala metales como el oro y la plata propiedades ópticas únicas. En particular, las nanopartículas de oro y plata muestran oscilaciones de densidad de carga de resonancias colectivas plasmones localizados en la superficie de la nanopartícula en el espectro visible. Aquí, nos centramos en la fabricación de arreglos periódicos de nanoestructuras plasmónica anisotrópico. Estas estructuras media concha (o nanocup) pueden exhibir adicional única luz flexión y dependiente de la polarización propiedades ópticas que simple nanoestructuras isotrópico no pueden. Los investigadores están interesados en la fabricación de arreglos periódicos de nanocups para una amplia variedad de aplicaciones tales como dispositivos ópticos de bajo costo, superficie-realzada Raman dispersión y alterar la indicación. Presentamos una técnica escalable basada en litografía coloidal en la que es posible fabricar fácilmente grandes arreglos periódicos de nanocups mediante spin-coating y uno mismo-montar nanoesferas poliméricos disponibles comercialmente. Microscopía y espectroscopia óptica desde el visible al infrarrojo cercano (cercano IR) fue realizado para confirmar éxito nanocup fabricación. Concluimos con una demostración de la transferencia de nanocups a una película adhesiva flexible, conformal.

Oro nanocups se prepararon con 170 nm diámetro poliestireno nanoesferas. Después de Recocer por 2 min a 107 ° C y el con una 75 W, 20 sccm O2 plasma por 165 s, la película resultante fue caracterizado utilizando SEM (figura 1). Para evaluar la calidad de la película spin-casted, óptica microscopia-además de inspección visual-mayo ser utilizado (figura 2). Películas de alta calidad deben ser esencialmente libre...

Watch this Scientific Journal Video about Fabrication of Periodic Gold Nanocup Arrays Using Colloidal Lithography at JoVE.com

Fabrication of Periodic Gold Nanocup Arrays Using Colloidal Lithography

Demostrar la fabricación de matrices de periódicos nanocup oro coloidal técnicas litográficas y discutir la importancia de las películas de nanoplasmonic.

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 ...

fabrication-periodic-gold-nanocup-arrays-using-colloidal

Research

JoVE Journal

Engineering

7.1K vistas.  Energy and Environment Directorate. Demostrar la fabricación de matrices de periódicos nanocup oro coloidal técnicas litográficas y discutir la importancia de las películas de nanoplasmonic.

Video: Fabrication of Periodic Gold Nanocup Arrays Using Colloidal Lithography

A Technique to Functionalize and Self-assemble Macroscopic Nanoparticle-ligand Monolayer Films onto Template-free Substrates

This protocol describes a self-assembly technique to create macroscopic monolayer films composed of ligand-coated nanoparticles1,2. The simple, robust and scalable technique efficiently functionalizes metallic nanoparticles with thiol-ligands in a miscible water/organic solvent mixture allowing for rapid grafting of thiol groups onto the gold nanoparticle surface. The hydrophobic ligands on the nanoparticles then quickly phase separate the nanoparticles from the aqueous based suspension and confine them to the air-fluid interface. This drives the ligand-capped nanoparticles to form monolayer domains at the air-fluid interface.&#160; The use of water-miscible organic solvents is important as it enables the transport of the nanoparticles from the interface onto template-free substrates.&#160; The flow is mediated by a surface tension gradient3,4 and creates macroscopic, high-density, monolayer nanoparticle-ligand films.&#160; This self-assembly technique may be generalized to include the use of particles of different compositions, size, and shape and may lead to an efficient assembly method to produce low-cost, macroscopic, high-density, monolayer nanoparticle films for wide-spread applications.

A simple, robust and scalable technique to functionalize and self-assemble macroscopic nanoparticle-ligand monolayer films onto template-free substrates is described in this protocol.

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

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

Investigación

Química

Synthesis, Assembly, and Characterization of Monolayer Protected Gold Nanoparticle Films for Protein Monolayer Electrochemistry

Colloidal gold nanoparticles protected with alkanethiolate ligands called monolayer protected gold clusters (MPCs) are synthesized and subsequently incorporated into film assemblies that serve as adsorption platforms for protein monolayer electrochemistry (PME). PME is utilized as the model system for studying electrochemical properties of redox proteins by confining them to an adsorption platform at a modified electrode, which also serves as a redox partner for electron transfer (ET) reactions. Studies have shown that gold nanoparticle film assemblies of this nature provide for a more homogeneous protein adsorption environment and promote ET without distance dependence compared to the more traditional systems modified with alkanethiol self-assembled monolayers (SAM).1-3 In this paper, MPCs functionalized with hexanethiolate ligands are synthesized using a modified Brust reaction4 and characterized with ultraviolet visible (UV-Vis) spectroscopy, transmission electron microscopy (TEM), and proton (1H) nuclear magnetic resonance (NMR). MPC films are assembled on SAM modified gold electrode interfaces by using a "dip cycle" method of alternating MPC layers and dithiol linking molecules. Film growth at gold electrode is tracked electrochemically by measuring changes to the double layer charging current of the system. Analogous films assembled on silane modified glass slides allow for optical monitoring of film growth and cross-sectional TEM analysis provides an estimated film thickness. During film assembly, manipulation of the MPC ligand protection as well as the interparticle linkage mechanism allow for networked films, that are readily adaptable, to interface with redox protein having different adsorption mechanism. For example, Pseudomonas aeruginosa azurin (AZ) can be adsorbed hydrophobically to dithiol-linked films of hexanethiolate MPCs and cytochrome c (cyt c) can be immobilized electrostatically at a carboxylic acid modified MPC interfacial layer. In this report, we focus on the film protocol for the AZ system exclusively. Investigations involving the adsorption of proteins on MPC modified synthetic platforms could further the understanding of interactions between biomolecules and man-made materials, and consequently aid the development of biosensor schemes, ET modeling systems, and synthetic biocompatible materials.5-8

Alkanethiolate stabilized gold colloids known as monolayer protected clusters (MPCs) are synthesized, characterized, and assembled into thin films as an adsorption interface for protein monolayer electrochemistry of simple redox protein like Pseudomonas aeruginosa azurin (AZ) and cytochrome c (cyt c).

Síntesis, de la Asamblea, y caracterización de una sola capa de nanopartículas de oro protegidas Films de Electroquímica de proteínas monocapa

Colloidal gold nanoparticles protected with alkanethiolate ligands called monolayer protected gold clusters (MPCs) are synthesized and subsequently ...

Bioingeniería

Colloidal Synthesis of Nanopatch Antennas for Applications in Plasmonics and Nanophotonics

We present a method for colloidal synthesis of silver nanocubes and the use of these in combination with a smooth gold film, to fabricate plasmonic nanoscale patch antennas. This includes a detailed procedure for the fabrication of thin films with a well-controlled thickness over macroscopic areas using layer-by-layer deposition of polyelectrolyte polymers, namely poly(allylamine) hydrochloride (PAH) and polystyrene sulfonate (PSS). These polyelectrolyte spacer layers serve as a dielectric gap in between silver nanocubes and a gold film. By controlling the size of the nanocubes or the gap thickness, the plasmon resonance can be tuned from about 500 nm to 700 nm. Next, we demonstrate how to incorporate organic sulfo-cyanine5 carboxylic acid (Cy5) dye molecules into the dielectric polymer gap region of the nanopatch antennas. Finally, we show greatly enhanced fluorescence of the Cy5 dyes by spectrally matching the plasmon resonance with the excitation energy and the Cy5 absorption peak. The method presented here enables the fabrication of plasmonic nanopatch antennas with well-controlled dimensions utilizing colloidal synthesis and a layer-by-layer dip-coating process with the potential for low cost and large-scale production. These nanopatch antennas hold great promise for practical applications, for example in sensing, ultrafast optoelectronic devices and for high-efficiency photodetectors.

A protocol for the colloidal synthesis of silver nanocubes and fabrication of plasmonic nanoscale patch antennas with sub-10 nm gaps is presented.

Coloidal Síntesis de Nanopatch antenas para aplicaciones en Plasmonics y Nanofotónica

We present a method for colloidal synthesis of silver nanocubes and the use of these in combination with a smooth gold film, to fabricate plasmonic ...

Ingeniería

Microfabrication of Nanoporous Gold Patterns for Cell-material Interaction Studies

Nanostructured materials with feature sizes in tens of nanometers have enhanced the performance of several technologies, including fuel cells, biosensors, biomedical device coatings, and drug delivery tools. Nanoporous gold (np-Au), produced by a nano-scale self-assembly process, is a relatively new material that exhibits large effective surface area, high electrical conductivity, and catalytic activity. These properties have made np-Au an attractive material to scientific community. Most studies on np-Au employ macro-scale specimens and focus on fundamental science of the material and its catalytic and sensor applications. The macro-scale specimens limit np-Au's potential in miniaturized systems, including biomedical devices. In order to address these issues, we initially describe two different methods to micropattern np-Au thin films on rigid substrates. The first method employs manually-produced stencil masks for creating millimeter-scale np-Au patterns, while the second method uses lift-off photolithography to pattern sub-millimeter-scale patterns. As the np-Au thin films are obtained by sputter-deposition process, they are compatible with conventional microfabrication techniques, thereby amenable to facile integration into microsystems. These systems include electrically-addressable biosensor platforms that benefit from high effective surface area, electrical conductivity, and gold-thiol-based surface bioconjugation. We describe cell culture, immunostaining, and image processing techniques to quantify np-Au's interaction with mammalian cells, which is an important performance parameter for some biosensors. We expect that the techniques illustrated here will assist the integration of np-Au in platforms at various length-scales and in numerous applications, including biosensors, energy storage systems, and catalysts.

We report on techniques to micropattern nanoporous gold thin films via stencil printing and photolithography, as well as methods to culture cells on the microfabricated patterns. In addition, we describe image analysis methods to characterize morphology of the material and the cultured cells using scanning electron and fluorescence microscopy techniques.

Microfabricación de los patrones de oro Nanoporous de Estudios de interacción célula-materiales

Nanostructured materials with feature sizes in tens of nanometers have enhanced the performance of several technologies, including fuel cells, biosensors, ...

Large Area Substrate-Based Nanofabrication of Controllable and Customizable Gold Nanoparticles Via Capped Dewetting

Recent scientific advances in the utilization of metallic nanoparticle for enhanced energy conversion efficiency, improved optical device performance, and high-density data storage have demonstrated the potential benefit of their use in industrial applications. These applications require precise control over nanoparticle size, spacing, and sometimes shape. These requirements have resulted in the use of time and cost intensive processing steps to produce nanoparticles, thus making the transition to industrial application unrealistic. This protocol will resolve this issue by providing a scalable and affordable method for the large-area production of nanoparticle films with improved nanoparticle control compared to the current techniques. In this article, the process will be demonstrated with gold, but other metals can also be used.

This protocol details a novel nano-manufacturing technique that can be used to make controllable and customizable nanoparticle films over large areas based on the self-assembly of dewetting of capped metal films.

Área base de sustrato nanofabricación de nanopartículas de oro personalizables y controlables Via Dewetting tapado

Recent scientific advances in the utilization of metallic nanoparticle for enhanced energy conversion efficiency, improved optical device performance, and ...

A Femtoliter Droplet Array for Massively Parallel Protein Synthesis from Single DNA Molecules

Advances in spatial resolution and detection sensitivity of scientific instrumentation make it possible to apply small reactors for biological and chemical research. To meet the demand for high-performance microreactors, we developed a femtoliter droplet array (FemDA) device and exemplified its application in massively parallel cell-free protein synthesis (CFPS) reactions. Over one million uniform droplets were readily generated within a finger-sized area using a two-step oil-sealing protocol. Every droplet was anchored in a femtoliter microchamber composed of a hydrophilic bottom and a hydrophobic sidewall. The hybrid hydrophilic-in-hydrophobic structure and the dedicated sealing oils and surfactants are crucial for stably retaining the femtoliter aqueous solution in the femtoliter space without evaporation loss. The femtoliter configuration and the simple structure of the FemDA device allowed minimal reagent consumption. The uniform dimension of the droplet reactors made large-scale quantitative and time-course measurements convincing and reliable. The FemDA technology correlated the protein yield of the CFPS reaction with the number of DNA molecules in each droplet. We streamlined the procedures about the microfabrication of the device, the formation of the femtoliter droplets, and the acquisition and analysis of the microscopic image data. The detailed protocol with the optimized low running cost makes the FemDA technology accessible to everyone who has standard cleanroom facilities and a conventional fluorescence microscope in their own place.

The overall goal of the protocol is to prepare over one million ordered, uniform, stable, and biocompatible femtoliter droplets on a 1 cm2 planar substrate that can be used for cell-free protein synthesis.

Un arreglo de gotas Femtoliter para la síntesis masiva de proteínas paralelas a partir de moléculas de ADN únicas

Advances in spatial resolution and detection sensitivity of scientific instrumentation make it possible to apply small reactors for biological and ...

Gold Nanoparticle Synthesis

Gold nanoparticles (Au nanoparticles) that are ~12 nm in diameter were synthesized by rapidly injecting a solution of 150 mg (0.15 mmol) of tetrachloroauric acid in 3.0 g (3.7 mmol, 3.6 mL) of oleylamine (technical grade) and 3.0 mL of toluene into a boiling solution of 5.1 g (6.4 mmol, 8.7 mL) of oleylamine in 147 mL of toluene. While boiling and mixing the reaction solution for 2 hours, the color of the reaction mixture changed from clear, to light yellow, to light pink, and then slowly to dark red. The heat was then turned off, and the solution was allowed to gradually cool down to room temperature for 1 hour. The gold nanoparticles were then collected and separated from the solution using a centrifuge and washed three times; by vortexing and dispersing the gold nanoparticles in 10 mL portions of toluene, and then precipitating the gold nanoparticles by adding 40 mL portions of methanol and spinning them in a centrifuge. The solution was then decanted to remove any remaining byproducts and unreacted starting materials. Drying the gold nanoparticles in a vacuum environment produced a solid black pellet; which could be stored for long periods of time (up to one year) for later use, and then redissolved in organic solvents such as toluene.

A protocol for synthesizing ~12 nm diameter gold nanoparticles (Au nanoparticles) in an organic solvent is presented. The gold nanoparticles are capped with oleylamine ligands to prevent agglomeration. The gold nanoparticles are soluble in organic solvents such as toluene.

Síntesis de nanopartículas de oro

Gold nanoparticles (Au nanoparticles) that are ~12 nm in diameter were synthesized by rapidly injecting a solution of 150 mg (0.15 mmol) of ...

Versatile Technique to Produce a Hierarchical Design in Nanoporous Gold

The potential to generate variable pore sizes, simplistic surface modification, and a breadth of commercial uses in the fields of biosensors, actuators, drug loading and release, and the development of catalysts have unquestionably accelerated the usage of nanoporous gold (NPG)-based nanomaterials in research and development. This article describes the process of the generation of hierarchical bimodal nanoporous gold (hb-NPG) by employing a step-wise procedure involving electrochemical alloying, chemical dealloying techniques, and annealing to create both macro- and mesopores. This is done to improve the utility of NPG by creating a bicontinuous solid/void morphology. The area available for surface modification is enhanced by smaller pores, while molecular transport benefits from the network of larger pores. The bimodal architecture, which is the result of a series of fabrication steps, is visualized using scanning electron microscopy (SEM) as a network of pores that are less than 100 nm in size and connected by ligaments to larger pores that are several hundred nanometers in size. The electrochemically active surface area of the hb-NPG is assessed using cyclic voltammetry (CV), with a focus on the critical roles that both dealloying and annealing play in creating the necessary structure. The adsorption of different proteins is measured by solution depletion technique, revealing the better performance of hb-NPG in terms of protein loading. By changing the surface area to volume ratio, the created hb-NPG electrode offers tremendous potential for biosensor development. The manuscript discusses a scalable method to create hb-NPG surface structures, as they offer a large surface area for the immobilization of small molecules and improved transport pathways for faster reactions.

Nanoporous gold with a hierarchical and bimodal pore size distribution can be produced by combining electrochemical and chemical dealloying. The composition of the alloy can be monitored via EDS-SEM examination as the dealloying process advances. The material's loading capacity can be determined by studying protein adsorption onto the material.

Técnica versátil para producir un diseño jerárquico en oro nanoporoso

The potential to generate variable pore sizes, simplistic surface modification, and a breadth of commercial uses in the fields of biosensors, actuators, ...

Large-area Scanning Probe Nanolithography Facilitated by Automated Alignment and Its Application to Substrate Fabrication for Cell Culture Studies

Scanning probe microscopy has enabled the creation of a variety of methods for the constructive (&#39;additive&#39;) top-down fabrication of nanometer-scale features. Historically, a major drawback of scanning probe lithography has been the intrinsically low throughput of single probe systems. This has been tackled by the use of arrays of multiple probes to enable increased nanolithography throughput. In order to implement such parallelized nanolithography, the accurate alignment of probe arrays with the substrate surface is vital, so that all probes make contact with the surface simultaneously when lithographic patterning begins. This protocol describes the utilization of polymer pen lithography to produce nanometer-scale features over centimeter-sized areas, facilitated by the use of an algorithm for the rapid, accurate, and automated alignment of probe arrays. Here, nanolithography of thiols on gold substrates demonstrates the generation of features with high uniformity. These patterns are then functionalized with fibronectin for use in the context of surface-directed cell morphology studies.

Here we present a protocol for wide-area scanning probe nanolithography enabled by the iterative alignment of probe arrays, as well as the utilization of lithographic patterns for cell-surface interaction studies.

Área análisis sonda Nanolitografía facilitado por alineación automática y su aplicación a la fabricación de sustrato para estudios del cultivo celular

Scanning probe microscopy has enabled the creation of a variety of methods for the constructive (&#39;additive&#39;) top-down fabrication of ...

Fabrication of Gradient Nanopattern by Thermal Nanoimprinting Technique and Screening of the Response of Human Endothelial Colony-forming Cells

Nanotopography can be found in various extracellular matrices (ECMs) around the body and is known to have important regulatory actions upon cellular reactions. However, it is difficult to determine the relation between the size of a nanostructure and the responses of cells owing to the lack of proper screening tools. Here, we show the development of reproducible and cost-effective gradient nanopattern plates for the manipulation of cellular responses. Using anodic aluminum oxide (AAO) as a master mold, gradient nanopattern plates with nanopillars of increasing diameter ranges [120-200&#8239;nm (GP 120/200), 200-280&#8239;nm (GP 200/280), and 280-360&#8239;nm (GP 280/360)] were fabricated by a thermal imprinting technique. These gradient nanopattern plates were designed to mimic the various sizes of nanotopography in the ECM and were used to screen the responses of human endothelial colony-forming cells (hECFCs). In this protocol, we describe the step-by-step procedure of fabricating gradient nanopattern plates for cell engineering, techniques of cultivating hECFCs from human peripheral blood, and culturing hECFCs on nanopattern plates.

Here, we present a protocol for the fabrication of gradient nanopattern plates via thermal nanoimprinting and the method of screening responses of human endothelial progenitor cells to the nanostructures. By using the described technology, it is possible to produce a scaffold that can manipulate cell behavior by physical stimuli.

Fabricación de Nanopattern gradiente térmico Nanoimprinting técnica y proyección de la respuesta de células formadoras de colonias endoteliales humanas

Nanotopography can be found in various extracellular matrices (ECMs) around the body and is known to have important regulatory actions upon cellular ...