Este trabalho foi financiado pela Fundação de Pesquisa Nacional da Coreia (2013R1A1A1061387) e fundo de investigação KU-KIST.

1. Preparação do Precursor <ol><li> Preparação de óxido de grafeno (GO): <ol><li> GO preparação pelo método de Hummer 14 modificado <ol><li> Adicionar 3,0 g de flocos de grafite, a uma mistura de H 2 SO 4 concentrado / H 3 PO 4 (360: 40 ml) à TA. (Nota: Especial cuidado deve ser tomado durante a utilização de ácidos fortes H 2 SO 4 e H 3 PO 4). </li><li> Adicionar KMnO4 (18,0 g) lentamente com agitação e arrefecimento num banho de gelo para manter a temperatura da mistura de reacção a &lt;35 ° C. (A solução tornar-se pegajoso com o aumento do tempo de reação, precisará usar método adequado para manter a agitação eficiente.) (Nota: Cuidado especial deve ser tomado ao adicionar KMnO4 devido à reacção exotérmica). </li><li> Agita-se durante 12 h a 50 ° C e depois arrefece-se para a TA e vertendo-se sobre gelo mistura de reacção (400 ml) contendo 30% de H 2 O 2 (3 mL). </li><li> Filtra-se a reaction mistura utilizando um metal padrão americana testar crivo (300 um) para remover grafite que não reagiu e o centrífuga (velocidade de 4.722 x g durante 2 horas) filtrado para remover o sobrenadante. </li><li> Repetir o passo de centrifugação com 200 ml de água, 200 ml de HCl a 30%, 200 ml de etanol, e água destilada até o pH novamente de solução alcance a 5,0-6,0. </li><li> Liofilizar as soluções finais para produzir um pó fofo GO. </li><li> A fim de fazer a solução de GO nanométricos, dissolver 20 mg de GO em pó em 40 ml de água destilada triplo (&gt; 18 mohms), e, em seguida, esfoliar por sonicação prolongada (35% de amplitude, a 500 W, 2 h) até que toda a distribuição do tamanho de tornar abaixo de 150 nm, em seguida, centrifugar-lo duas vezes (velocidade de 10.625 xg, 15 min) para remover precipitados (folhas grandes GO esfoliada-ONU). </li></ol></li></ol></li><li> Preparação de nanopartículas plasmonic <ol><li> Preparação de AuNPs <ol><li> Estabilizado com citrato de forma esférica de nanopartículas de ouro (AuNPs, OD = 1,0) tamanho de partículas de 30 nm foi utilizado para a redução de R-GO. </li></ol></li><li> Preparação de 15 AuNRs <ol><li> Preparar a solução de sementes pela adição de 0,6 ml de solução gelada preparada de fresco de NaBH4 solução (0,01 M) a uma solução de mistura de composição aquosa de 0,25 ml de HAuCl 4 (0,01 M) e 9,75 ml de brometo de cetiltrimetilamónio (CTAB, 0,1 M ). </li><li> Agita-se a mistura resultante vigorosamente durante 0,5 minutos e depois mantê-la a 28 ° C durante 3 h. </li><li> Preparar a solução de crescimento através da mistura de 475 ml de CTAB (0,1 M), 3 mL de AgNO3 (0,01 M) e 20 ml de HAuCl 4 (0,01 M). </li><li> Em seguida, adicione preparada de fresco 3,2 ml de ácido ascórbico (0,01 M) à mistura seguido pela adição de 0,8 ml de uma solução aquosa de HCl (1,0 M). </li><li> No passo final, adicionar 3,2 ml de solução de sementes à solução de crescimento a 28 ° C e submeter a mistura reaccional a rápida inversão durante alguns segundos. Finalmente, keep a mistura resultante em repouso durante pelo menos 6 horas. </li><li> Analisar os AuNRs preparados com espectroscopia de UV-Visível para absorção máxima (λ max) e análise de TEM (tipicamente a relação de aspecto λ max e verificou-se ser 730 nm e 3,5, respectivamente). </li></ol></li><li> Preparação de 16 AuNSs <ol><li> Preparar uma solução aquosa estoque de 4- (2-hidroxietil) -1-piperazinoetanossulfónico ácido (HEPES) com a concentração de 100 mM e ajustar o pH a 7,4 a 25 ° C através da adição de solução 1,0 M de NaOH. </li><li> Misturar 20 ml de tampão de fosfato (100 mM) com 30 ml de 2- [4- (2-hidroxietil) -1-piperazinil] etanossulfónico (100 mM). </li><li> Em seguida, adicionar 500 mL de tri-hidrato de ouro (III), cloreto de (20 mM) à mistura acima e manter a 28,5 ° C durante 30 min em banho de água. Solução mudanças de cor de amarelo claro para azul esverdeado depois de 30 minutos pode ser observada. </li><li> Centrifugar a solução a velocidade de 8.928 xg durante 30 min e dispersarOs precipitados em água destilada. </li><li> Finalmente, analisar o AuNSs preparado com espectroscopia UV-Visível para absorção máxima (λ max) e análise TEM para a confirmação de tamanho das partículas que é encontrado para ser 740 nm e 30 nm, respectivamente. </li></ol></li></ol></li></ol> 2. Preparação de r-GO Usando luz visível e AuNPs <ol><li> Adicionar 1 ml de nanopartículas plasmonic (ABS 1.0 a 520 nm para AuNPs, Abs 1,0 a 750 nm para AuNRs, e Abs 1,0 a 730 nm para AuNSs, respectivamente) e 100 ul de hidróxido de amónio (28%, w / v%) para 10 ml de solução de GO (1,0 OD a 230 nm, 0,125 mg ml -1) colocado em um reactor de vidro Pyrex equipado com uma camisa com circulação de água. </li><li> Irradiar a mistura com lâmpada Xe (densidade de potência de 1,56 W cm2) durante 30 minutos com a circulação de água através do revestimento com circulação de água para manter a temperatura a 25 ° C e depois centrifugar a solução a uma velocidade 10.625 xg durante 15 min pararemover nanopartículas de ouro. </li><li> Tome-se o sobrenadante contendo a r-ir para analisar com espectrofotómetro de UV-Visível (R-GO deve mostrar a banda de absorção característico a 270 nm) na gama de 200-900 nm preparado. </li></ol> 3. Detecção do ADN Alvo Utilizando R-GO 17 Solução <ol><li> Por extinção de fluorescência, adicionar 20 ul de 10 -6 M ssDNA Cy3-modificado (5&#39;-ATC CTT ATC AAT ATT TAA CAA TAA TCC CTC-Cy3-3 &#39;) em solução GO ou r-GO contendo 25 ul de GO (0,125 mg ml-1) ou R-GO (0,125 mg mL -1), em 1,955 ml de solução 0,3 M de PBS (tampão fosfato 10 mM, NaCl 0,3 M) e incubar durante 10 min à temperatura ambiente. </li><li> Medir a intensidade de fluorescência destas amostras com espectrofluorímetro (λ ex = 529 nm). </li><li> Para a detecção do alvo, adicione 200 ml de solução de oligonucleotídeo alvo (5&#39;-GAG GGA ATT TTG TTA AAT ATT GAT AAG GAT- 3 &#39;) em três concentrações diferentes (10 -6 &lt;/ sup&gt; M, 10 -7 M, 10 -8 M) na solução de GO ou R-GO contendo 20 ul de 10 -6 M ADNcs-Cy3, 25 ul de GO ou R-GO (0,125 mg mL -1) , e 1,755 mL de 0,3 M de PBS para a experiência de recuperação de fluorescência. 17 Notas: Fontes de Luz e Reactor A luz visível (400-780 nm) de origem. A luz visível irradiar através Pyrex reator de vidro (diâmetro janela = 1,1 cm), contendo solução GO usando lâmpada Xe (1,56 W / cm 2 de energia). A energia dos fotões aplicada ao reactor é calculada como sendo de 4,8 x 10 21 fótons por min (Figura 2A-2C). Infravermelho próximo (NIR) laser. NIR laser (diâmetro janela = 13,2 cm) com uma densidade de potência de 0,36 W / cm 2, e comprimento de onda de funcionamento de 808 nm foi utilizada como a fonte de luz do infravermelho próximo para reacções de redução GO (Figura 2E). A energia do fóton é calculada para ser 2,43 × 10 21 fótons por min. Reactor: Pyrex reator de vidro (diâmetro janela = 1,1 cm; volume de reacção = 10 ml) equipado com uma jaqueta com circulação de água é utilizada para luz visível e NIR luz irradiada reações de redução GO (Figura 2F). </li></ol>

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Não temos nada a divulgar.

Visível irradiação de luz em solução GO durante 30 minutos com nanopartículas de ouro (AuNPs, AuNSs &amp; AuNRs) mostrou as mudanças de cor rápidas de luz amarela-marrom a cor preta (Figura 1). Para obter produto altamente puro de R-GO, com elevado rendimento, existem dois factores importantes precisa seguir. Um deles é o uso de um catalisador como AuNPs plasmonic eficiente, uma vez que pode absorver AuNPs fortemente a luz visível, entre outras estruturas (por exemplo, AuNRs, AuNSs). ...

<html> Método 1 e de vapor químico baseado o primeiro scotch-tape desenvolvido deposição 2 foram excelentes métodos para produzir o estado primitivo de um grafeno, mas a formação da camada de síntese de grafeno em grande escala ou grafeno na superfície com área ampla, foram considerados como uma limitação fundamental do métodos anteriores 3 Uma de solução possível para grande escala de síntese de R-GO será método sintético molhado-química que requer em primeiro lugar as reacções com agentes de oxidação fortes, extenso tratamento físico tal como sonicação para produzir VAI folha, e, finalmente, a redução de funcionalidades de oxigénio tal. como hidroxilo, epóxido e grupos carbonilo em GO é essencial, a fim de recuperar as suas propriedades físicas originais Principalmente 4., a redução de GO foi levada a cabo com qualquer método químico usando hidrazina ou dos seus derivados 5 ou por método de tratamento térmico (° 550-1,100 C) numa atmosfera inerte ou redutora. 6 jove_content &quot;&gt; Estes processos necessitam dos produtos químicos tóxicos, longo tempo de reação e temperatura elevada que o aumento da demanda total de energia para a síntese de r-GO. 7 Enquanto os processos de redução de irradiação de fotos, tais como, processo 8 foto-térmico induzido por UV usando um pulsada de xenônio flash, 9 pulsada a laser assistida 10 e fotoï¿½tï¿½rmica aquecimento com luzes de flash da câmara 11 também foram descritos para a preparação de R-GO. Em geral, a baixa eficiência de conversão dos métodos foto-induzidas propagada para o uso de UV ou pulsada irradiação laser que pode oferecer alta energia dos fótons. A energia do fóton baixo da luz visível limita o seu uso e não atraiu muito para a síntese de r-GO. Excelentes propriedades de absorção de luz de nanopartículas plasmonic nas regiões visíveis e / ou NIR pode melhorar significativamente as desvantagens atuais da utilização de luz visível para a síntese de R-GO. 12,13 condições de reacção suaves, curto tempo de reacção e utilização limitada de CH tóxicoemicals poderia fazer a luz visível plasmon induzida assistida redução fotocatalítica de GO como um método alternativo útil. No presente método, nós descrevemos o método sintético r-GO eficiente e simples, usando nanopartículas plasmonic e luz visível. O progresso da reacção foi encontrado para ser fortemente dependente das estruturas de nanopartículas plasmonic tais como as nanopartículas de ouro (esféricas AuNPs), ouro nanorods (AuNRs), e nanostars ouro (AuNSs). O uso de AuNPs mostrou a redução mais eficiente de GO e as nanopartículas são facilmente removíveis e reciclável para o uso repetido (Figura 1). A r-GO sintetizado usando a luz visível e AuNPs mostrou quase igual qualidade em comparação com o r-GO preparados por método químico conhecido (hidrazina) como demonstrado pelo uso de várias medições analíticas e do método de detecção de ADN com base extinção de fluorescência / recuperação.

<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

O presente trabalho demonstra a e método simples, química livre, rápido, eficiente da energia para produzir reduzida solução de óxido de grafeno (r-GO) à temperatura ambiente usando a luz visível irradiação com nanopartículas plasmonic. A nanopartícula plasmonic é utilizado para melhorar a eficiência de redução de GO. Leva apenas 30 min à temperatura ambiente, iluminando as soluções com Xe-lâmpada, as soluções de r-Go pode ser obtido por remoção completamente nanopartículas de ouro através de uma simples etapa de centrifugação. As nanopartículas de ouro esférico (AuNPs) em comparação com as outras nanoestruturas é a nanoestrutura plasmonic mais adequados para a preparação de R-GO. O óxido de grafeno reduzido preparados utilizando luz visível e AuNPs foi igualmente qualitativa como quimicamente reduzida óxido de grafeno, que foi apoiado por várias técnicas analíticas, tais como espectroscopia UV-Vis, espectroscopia Raman, pó de DRX e XPS. O óxido de grafeno reduzido preparado com luz visível mostra excelentes propriedades de têmpera sobre o fluormoléculas escent modificado em ADNcs e excelente recuperação de fluorescência para a detecção de ADN alvo. É encontrado o r-GO preparado por AuNPs reciclados para ser de mesma qualidade com que quimicamente reduzida de r-GO. A utilização de luz visível com nanopartículas plasmonic demonstra a boa método alternativo para a síntese de R-GO.

A Figura 1 mostra o esquema geral para a luz visível e reacção de redução à base de nanopartículas plasmonic R-GO. A Figura 2 mostra a configuração instrumental para as reacções. Depois da reacção, é necessário o passo de centrifugação para remover o fotocatalisador utilizado (AuNSs, AuNRs, ou AuNPs) como mostrado na Figura 3A. A análise HRTEM mostra a remoção completa das nanopartículas no sobrenadante (R-GO) (Figura 3B),</...

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

Um protocolo simples para a preparação de óxido de grafeno reduzido utilizando luz visível e nanopartículas plasmonic é descrito.

De luz visível redução induzida de óxido de grafeno Usando nanopartículas plasmonic

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 visualizações.  Korea University.  Um protocolo simples para a preparação de óxido de grafeno reduzido utilizando luz visível e nanopartículas plasmonic é descrito. 

Vídeo: 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.

Dirigido modelo de síntese de nanotubos de Ouro plasmônicos com Absorbância IR Tunable

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

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.

Avaliando plasmônicos Transporte em Prata atual de transporte de nanofios

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

Engenharia

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.

Utilização de Nanoestruturas Cristal plasmônicos e Fotônica para Manipulação de Micro-e Nanopartículas melhorada

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

Bioengenharia

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.

Híbrido multifuncional Fe<sub&gt; 2</sub&gt; ó<sub&gt; 3</sub&gt; -au Nanopartículas para Aquecimento plasmonic Eficiente

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 Síntese de Nanopartículas de Ouro sem agregação no espaço Interlayer de Layered titanato filmes 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.

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 ...

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.

Determinação de excitação e taxas entre emissores de luz e Polaritons de Plasmon de superfície de acoplamento

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.

Realização de espectroscopia em nanopartículas Plasmonicas com microscopia de contraste de interferência diferencial de tipo Nomarski baseado em transmissão

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.

Fotodeposição de PD em au Nanorods coloidal pela excitação de superfície Plasmon

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.

Quasi-van der Waals Estributivo assistido por grafeno de Filme aln em substrato de safira nano-padronizado para diodos emissores 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 ...