Esta pesquisa foi realizada no laboratório nacional Noroeste Pacífico (PNNL), que é operado pelo Battelle Memorial Institute para o departamento de energia (DOE) sob o n º do contrato DE-AC05-76RL01830. Os autores reconhecem com gratidão apoio do departamento de estado dos EUA, através do fundo de ativos de verificação chave (V fundo) sob SIAA15AVCVPO10 de acordo interinstitucional.

1. preparação de material <ol><li>coloque vários wafers de silício de 2 pol. em um portador de quartzo para limpeza e carregar os wafers de silício para o sistema de condicionamento de plasma. Bomba a câmara de vácuo para baixo até que ele atinja pelo menos 75 mTorr. Isto pode levar alguns minutos.</li>
	<li>Começar o fluxo de gás de O 2 (30 sccm) e permitir que a pressão estabilizar. Defina o tempo de gravar a 15 min. Uma vez que a pressão da câmara se estabilizou iniciar plasma radiofrequência (RF) 13,56 MHz 250 W. 
	Nota: Este passo limpa os wafers de silício de qualquer orgânica contamina e functionalizes a superfície com hidroxilados (-OH) partes, assegurando assim uma superfície hidrofílica.</li>
	<li>Enquanto espera para a limpeza de plasma passo para finalizar, retire as adquiridos comercialmente nanoesferas de poliestireno (170 nm de diâmetro, 10% de sólidos, 0,5% de sódio Dodecil sulfato) da geladeira (4 ° C). Permitir que o contêiner aquecer a temperatura ambiente.</li>
	<li>Brevemente vórtice (1 min) e proceda à sonicação (35 kHz, 1 min), as poliestireno nanoesferas para minimizar a aglomeração nanosphere.</li>
	<li>Dentro de um frasco de vidro limpo, medir 1,0 mL das nanoesferas de poliestireno 170 nm e adicionar 1,0 mL de H 2 O para obter uma suspensão coloidal de 5% de sólidos.</li>
	<li>Depois de 15 min, interromper o fluxo de O 2, ventilar a câmara de vácuo e retire as bolachas recém limpas.</li>
</ol> 2. Rotação-revestimento de poliestireno nanoesferas modelo <ol><li>descarregar o silício limpo bolachas do gravador de plasma. Em seguida, monte um wafer de 2 pol. para o spin-revestidor. Certifique-se de que está bem centrada e que o-Ring está livre de quaisquer detritos. Iniciar o aspirador e certifique-se de que a hóstia está bem presa ao palco.</li>
	<li>Definir os parâmetros de rotação de camada a rotação. Esses parâmetros variam com base no tamanho nanosphere. Para uma solução de 5% 170 nm nanoesferas, definir a rotação-aplicador para um processo de 1 passo com um tempo de 1 min, uma velocidade de 3.000 rpm e uma aceleração de 2.000 rpm/s.</li>
	<li>Usando uma seringa descartável, retirar ~ 1 mL de suspensão coloidal do frasco. Reserve o frasco. Pegue um filtro de seringa 5 µm e coloque-o na extremidade da seringa. Pressione a seringa até que uma gota de suspensão limpa a ponta. O filtro remove indesejáveis agregados e partículas que pode reduzir significativamente a qualidade do filme.</li>
	<li>Depósito suficiente suspensão diretamente no centro do wafer tal que aproximadamente 2/3 da superfície é coberta. Tente minimizar bolhas porque aqueles podem afetar a qualidade do filme. Feche a tampa do aplicador de rotação e pressione Iniciar. Durante esse processo, é possível ver os efeitos de interferência de película fina na superfície do wafer como as nanoesferas auto-montagem. Isso irá variar com base no diâmetro nanosphere.</li>
	<li>Remover a bolacha revestido de rotação depois de desactivar o vácuo. Limpe a bacia e a tampa da rotação-aplicador para remover o excesso nanoesferas.</li>
</ol> 3. Avaliação da qualidade e preparação para a gravura de cinema <ol><li>visualmente para avaliar a qualidade do filme Self montado pela procura de defeitos visíveis como listras ou furos que podem ter sido causados por partículas durante o processo de rotação-revestimento.</li>
	<li>Para avaliar a qualidade do filme, colocando a bolacha debaixo de um microscópio óptico. Limites de grão e alguns defeitos são normais. Se a bolacha tem grandes áreas sem revestimento ou multicamadas óbvias, é necessário ajustar os parâmetros de rotação para obter um filme mais uniforme. Microscopia eletrônica também pode ser utilizada para avaliar a qualidade do filme.</li>
	<li>Ligar a fonte de luz para o microscópio e o foco para a superfície da bolacha de silício usando um objectivo X 20. Avaliar a qualidade em vários pontos durante todo o wafer de garantir uniformidade.</li>
	<li>a qualidade do filme final verificar é a utilização de microscopia eletrônica de varredura (SEM) para visualizar o nanosphere auto-montagem em nanoescala. É possível avaliar o grau de multicamadas, buracos e limites de grão/defeitos em pequenas porções de wafer relativamente rapidamente usando esta técnica.</li>
	<li>, Uma vez que se obteve um filme suficiente, coloque a bolacha dentro de um forno (107 ° C) por 2 min recozer as nanoesferas Self montadas. Isso ajuda a incentivar a adesão ao substrato e produz uma superfície de nanopatterned melhor após condicionamento.</li>
</ol> 4. Gravura, deposição de Metal e caracterização óptica <ol><li>carregar o wafer recozido para o gravador de plasma e iniciar a bomba abaixo processo.</li>
	<li>, Uma vez que a câmara de vácuo atinge pelo menos 75 mTorr, começar o fluxo de gás de O 2 (20 sccm) e aguarde a pressão estabilizar. Iniciar o plasma RF (75 W) para 165 s.</li>
	<li>Quando estiver concluído o ciclo de plasma RF, interromper o fluxo de O 2 e a câmara de ventilação.</li>
	<li>o substrato está gravada e pronta para a deposição de metal. Transporte da amostra para um sputter coater e depositar uma fina (20 nm) camada de ouro. Variando de ângulos de deposição pode ser usado para alterar as propriedades ópticas do nanocups. Neste caso, a deposição de metais normalmente incidente ao substrato foi realizada.</li>
	<li>Após a deposição de metais, o substrato pode ser caracterizado usando espectroscopia óptica. Concentre-se a microspectrophotometer sobre a superfície do substrato metalizado e medir os espectros de reflectância. Para 170 nm gravado nanosphere matrizes, o LECC foi no 615 nm.</li>
	<li>Usando fita de adesivo sensível à pressão, coloque delicadamente o filme em contacto com o substrato. Pode ser necessário remover quaisquer bolhas de ar que se formou na interface usando uma pinça.</li>
	<li>, Uma vez que a fita está em contacto com o substrato, a fita pode ser imediatamente descascada para remover o nanocups da superfície do substrato. Delicadamente a casca volta a fita e o resultado é uma película flexível e conformal de ouro nanocups.</li>
</ol>

<ol>
	<li>Fang, Y., Sun, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Nanoplasmonic+waveguides:+towards+applications+in+integrated+nanophotonic+circuits.">Nanoplasmonic waveguides: towards applications in integrated nanophotonic circuits.</a> Light Sci Appl. 4, e294 (2015).</li><li>Li, J. F., Anema, J. R., Wandlowski, T., Tian, Z. Q. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Dielectric+shell+isolated+and+graphene+shell+isolated+nanoparticle+enhanced+Raman+spectroscopies+and+their+applications.">Dielectric shell isolated and graphene shell isolated nanoparticle enhanced Raman spectroscopies and their applications.</a> Chemical Society Reviews. 44 (23), 8399-8409 (2015).</li><li>Wang, 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=Large+Area+Plasmonic+Color+Palettes+with+Expanded+Gamut+Using+Colloidal+Self-Assembly.">Large Area Plasmonic Color Palettes with Expanded Gamut Using Colloidal Self-Assembly.</a> ACS Photonics. , (2016).</li><li>Taylor, A. B., Michaux, P., Mohsin, A. S. M., Chon, J. W. 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. S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Angle-+and+Spectral-Dependent+Light+Scattering+from+Plasmonic+Nanocups.">Angle- and Spectral-Dependent Light Scattering from Plasmonic Nanocups.</a> ACS Nano. 5 (9), 7254-7262 (2011).</li><li>Mirin, N. A., Halas, N. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Light-Bending+Nanoparticles.">Light-Bending Nanoparticles.</a> Nano Letters. 9 (3), 1255-1259 (2009).</li><li>Eggleston, M. S., Messer, K., Zhang, L., Yablonovitch, E., Wu, M. 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Os autores não têm nada para divulgar.

Este protocolo demonstra uma técnica eficiente e de baixo custo para a fabricação de matrizes periódicas de plasmônico nanocups ouro. Esta técnica é particularmente vantajosa porque evita série descendente processos tais como litografia de feixe de elétrons ou feixe de íon focalizado de trituração. A técnica apresentada mostra que nanoesferas poliméricas comercialmente disponíveis podem ser montadas self de uma maneira simples para servir como um modelo de tamanho nano para processamento adicional.
<p ...

O surgimento de plasmonics em conjunto com técnicas de síntese e nanofabricação melhorada ter trazido sobre uma ampla variedade de tecnologias excitantes tais como sub difração limitada os circuitos, detecção avançada de química ede sensoriamento óptico 1 ,2,3. Neste protocolo, demonstramos uma técnica escalável e de custo relativamente baixo capaz de fabricar nanopatterned plasmônico substratos usando nanoesferas poliméricas comercialmente disponíveis e uma etapa de condicionamento seguido por deposição de metal. Ao contrário de outras técnicas para fabricar nanopatterned de substratos, tais como o elétron feixe litografia4, esta técnica pode rapidamente e eficientemente ser escalada para wafers de 300 mm e além, com o mínimo de esforço e usos uma transferência passo para produzir flexível e conformal filmes5.
Desde a época romana, sabemos que certos metais como ouro e prata podem ter propriedades óticas brilhantes quando são finamente divididos. Hoje, entendemos que estas partículas metálicas apresentam um efeito chamado "ressonância de plasmon de superfície localizada" (LECC), quando suas dimensões se aproxima à escala nanométrica. LECC é análogo a uma onda estacionária, na qual elétrons fracamente ligados, encontrados no metal coerentemente oscilam quando a luz de determinadas frequências ilumina as partículas de metal. Nanoestruturas anisotrópicas são de particular interesse porque ressonâncias ópticas exclusivas podem surgir como resultado de6,7,8da simetria.
A iluminação de estruturas (nanocup) meia-concha com luz pode excitar modos de plasmon de dipolo magnético, dependendo de fatores como o ângulo de deposição do metal, a orientação do substrato em relação a luz incidente, ou dipolo elétrico e a polarização da luz incidente9. Nanocups muitas vezes têm sido considerados análogos ao tridimensionais ressonadores-split-anel, no qual a frequência de ressonância pode aproximadas como um oscilador LC10,11. A frequência de ressonância para o tamanho de nanoesferas poliméricas usados aqui (170 nm), a quantidade de ouro depositado (20 nm), e as taxas de ataque ácido produzem frequências de ressonância, abrangendo o visível e próximo-ir
As propriedades ópticas de nanocups o ouro podem ser medidas em transmissão ou reflexão, dependendo do substrato utilizado para o revestimento de rotação. O protocolo apresentado, escolhemos usar wafers de silício de 2 pol. como substrato e executar medidas de refletância depois da deposição de metal. As medições foram realizadas utilizando um microscópio acoplado a um espectrômetro dispersivo com uma fonte de luz halógena. Também tivemos sucesso com o uso de substratos de vidro, permitindo a transmissão e reflexão medições imediatamente após a deposição de metal. Além disso, esta técnica pode ser facilmente dimensionada e não está limitada a bolachas de 2 pol.. Devido à ampla comercial disponibilidade de nanoesferas poliméricas monodisperso de alta qualidade, é simples para ajustar as propriedades ópticas dessas estruturas, simplesmente iniciando com nanoesferas de diferente tamanhos.
Neste protocolo, uma técnica para fabricar anisotrópico ouro meia-concha (ou nanocup), usando um método chamado litografia coloidal de nanoestruturas é demonstrada. Coloidal litografia usa auto-montagem de altamente monodisperso nanosphere poliméricos para rapidamente padrão de um substrato que pode ser subsequentemente transformado em um substrato plasmônico depois por pulverização catódica, revestimento com uma camada fina de ouro. Da mesma forma, é possível ajustar a anisotropia do substrato pela inclinação do substrato de amostra durante a deposição de metal. As estruturas resultantes são sensíveis à polarização devido a anisotropia do nanostructure formado. Aqui, demonstramos um particular caso e realizar caracterização óptica e decolagem para transferir as estruturas para uma película transparente, flexível.

<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

Nos últimos anos, o campo de plasmonics explodiu como pesquisadores demonstraram excitantes aplicações relacionadas com a química e a óptica sensoriamento em combinação com novas técnicas de nanofabricação. Um plasmon é um quantum de oscilação de densidade de carga que empresta a nanoescala metais como ouro e prata exclusivos propriedades óticas. Em particular, nanopartículas de ouro e prata apresentam oscilações de densidade de carga de ressonâncias-coletivo de plasmon de superfície localizadas na superfície de nanopartículas-ao espectro visível. Aqui, focalizamos a fabricação de matrizes periódicas de nanoestruturas plasmônico anisotrópicas. Estas estruturas meia-concha (ou nanocup) podem exibir adicional única luz de flexão e dependente da polarização propriedades ópticas que nanoestruturas isotrópica simples não podem. Os pesquisadores estão interessados na fabricação de matrizes periódicas de nanocups para uma ampla variedade de aplicações, tais como aparelhos ópticos de baixo custo, superfície-enhanced Raman dispersando e indicação da calcadeira. Apresentamos uma técnica escalável baseada em litografia coloidal, em que é possível fabricar facilmente grandes matrizes periódicas de nanocups usando a rotação-revestimento e auto montada nanoesferas poliméricas comercialmente disponíveis. Microscopia eletrônica de varredura e espectroscopia ótica do visível ao infravermelho (infravermelho próximo) foi realizada para confirmar o sucesso nanocup fabricação. Concluímos com uma demonstração da transferência de nanocups para uma película adesiva flexível, conformal.

Nanocups de ouro foram preparadas usando 170 nm de diâmetro nanoesferas poliestireno. Após recozimento por 2 min a 107 ° C e gravura com um 75 W, 20 sccm O2 plasma para 165 s, o filme resultante foi caracterizado usando SEM (Figura 1). Para avaliar a qualidade do filme girar-fundido, óptica microscopia-além de inspeção visual-maio ser usado (Figura 2). Filmes de alta qualidade devem ser essencialmente livres de ...

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Fabrication of Periodic Gold Nanocup Arrays Using Colloidal Lithography

Demonstramos a fabricação de matrizes de periódicos nanocup ouro usando técnicas litográficas coloidais e discutir a importância dos filmes nanoplasmonic.

Fabricação de matrizes de periódicos Nanocup ouro usando litografia coloidal

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

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Research

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7.1K visualizações.  Energy and Environment Directorate. Demonstramos a fabricação de matrizes de periódicos nanocup ouro usando técnicas litográficas coloidais e discutir a importância dos filmes nanoplasmonic.

Vídeo: 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.

Uma técnica para funcionalizar e auto-montar macroscópicas Nanopartículas-ligante monocamada Films em substratos sem Modelo

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

Química

Nanofabrication of Gate-defined GaAs/AlGaAs Lateral Quantum Dots

A quantum computer is a computer composed of quantum bits (qubits) that takes advantage of quantum effects, such as superposition of states and entanglement, to solve certain problems exponentially faster than with the best known algorithms on a classical computer. Gate-defined lateral quantum dots on GaAs/AlGaAs are one of many avenues explored for the implementation of a qubit. When properly fabricated, such a device is able to trap a small number of electrons in a certain region of space. The spin states of these electrons can then be used to implement the logical 0 and 1 of the quantum bit. Given the nanometer scale of these quantum dots, cleanroom facilities offering specialized equipment- such as scanning electron microscopes and e-beam evaporators- are required for their fabrication. Great care must be taken throughout the fabrication process to maintain cleanliness of the sample surface and to avoid damaging the fragile gates of the structure. This paper presents the detailed fabrication protocol of gate-defined lateral quantum dots from the wafer to a working device. Characterization methods and representative results are also briefly discussed. Although this paper concentrates on double quantum dots, the fabrication process remains the same for single or triple dots or even arrays of quantum dots. Moreover, the protocol can be adapted to fabricate lateral quantum dots on other substrates, such as Si/SiGe.

This paper presents a detailed fabrication protocol for gate-defined semiconductor lateral quantum dots on gallium arsenide heterostructures. These nanoscale devices are used to trap few electrons for use as quantum bits in quantum information processing or for other mesoscopic experiments such as coherent conductance measurements.

Nanofabricação de GaAs / AlGaAs Quantum Dots laterais de porta definidos

A quantum computer is a computer composed of quantum bits (qubits) that takes advantage of quantum effects, such as superposition of states and ...

Engenharia

Ultrahigh Density Array of Vertically Aligned Small-molecular Organic Nanowires on Arbitrary Substrates

In recent years &pi;-conjugated organic semiconductors have emerged as the active material in a number of diverse applications including large-area, low-cost displays, photovoltaics, printable and flexible electronics and organic spin valves. Organics allow (a) low-cost, low-temperature processing and (b) molecular-level design of electronic, optical and spin transport characteristics. Such features are not readily available for mainstream inorganic semiconductors, which have enabled organics to carve a niche in the silicon-dominated electronics market. The first generation of organic-based devices has focused on thin film geometries, grown by physical vapor deposition or solution processing. However, it has been realized that organic nanostructures can be used to enhance performance of above-mentioned applications and significant effort has been invested in exploring methods for organic nanostructure fabrication.	
A particularly interesting class of organic nanostructures is the one in which vertically oriented organic nanowires, nanorods or nanotubes are organized in a well-regimented, high-density array. Such structures are highly versatile and are ideal morphological architectures for various applications such as chemical sensors, split-dipole nanoantennas, photovoltaic devices with radially heterostructured "core-shell" nanowires, and memory devices with a cross-point geometry. Such architecture is generally realized by a template-directed approach. In the past this method has been used to grow metal and inorganic semiconductor nanowire arrays. More recently &pi;-conjugated polymer nanowires have been grown within nanoporous templates. However, these approaches have had limited success in growing nanowires of technologically important &pi;-conjugated small molecular weight organics, such as tris-8-hydroxyquinoline aluminum (Alq3), rubrene and methanofullerenes, which are commonly used in diverse areas including organic displays, photovoltaics, thin film transistors and spintronics.	
Recently we have been able to address the above-mentioned issue by employing a novel "centrifugation-assisted" approach. This method therefore broadens the spectrum of organic materials that can be patterned in a vertically ordered nanowire array. Due to the technological importance of Alq3, rubrene and methanofullerenes, our method can be used to explore how the nanostructuring of these materials affects the performance of aforementioned organic devices. The purpose of this article is to describe the technical details of the above-mentioned protocol, demonstrate how this process can be extended to grow small-molecular organic nanowires on arbitrary substrates and finally, to discuss the critical steps, limitations, possible modifications, trouble-shooting and future applications.

We report a simple method for fabricating an ultrahigh density array of vertically ordered small-molecular organic nanowires. This method allows for synthesis of complex heterostructured hybrid nanowire geometries, which can be inexpensively grown on arbitrary substrates. These structures have potential applications in organic electronics, optoelectronics, chemical sensing, photovoltaics and spintronics.

Ultra Density Array of alinhados verticalmente Nanofios orgânicos pequeno-moleculares sobre substratos Arbitrárias

In  recent years &pi;-conjugated  organic semiconductors have emerged as the active material in a number of  diverse applications including large-area, ...

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).

Síntese, Assembléia e Caracterização de monocamada Protected Films nanopartículas de ouro para Eletroquímica monocamada Protein

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

Bioengenharia

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 Síntese de nanopatch Antenas para aplicações em plasmônica e 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 ...

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.

Microfabricação de Padrões de Ouro Nanoporosos para celular-primas estudos de interacção

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.

Nanofabricação baseado em substrato de grande área de nanopartículas de ouro controláveis e personalizáveis através de Dewetting tampado

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

Síntese de Nanopartículas de Ouro

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

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.

Grande área varredura sonda Nanolitografia facilitada pelo alinhamento automatizado e sua aplicação para fabricação de substrato para estudos de cultura 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.

Fabricação de gradiente Nanopattern pela técnica de Nanoimprinting térmica e rastreio da resposta das células formadoras endoteliais humanas

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