Este trabalho foi apoiado com financiamento concedido a partir do Escritório de Pesquisa Naval. J. Fontana reconhece o Conselho Nacional de Pesquisa para um associativismo de pós-doutorado.

1. Monolayers Ligand nanopartículas auto-montados Como um exemplo ilustrativo da técnica de auto-montagem, macroscópicas, tampado filmes monocamada de nanoesferas ouro tiol-alcano são produzidos como se segue: <ol><li> Concentre-se 15 nm nanoesferas de ouro (comercialmente disponíveis a uma densidade número: 10 12 partículas / ml) para ~ 10 13 partículas / ml em água. <ol><li> Colocar 15 ml de água a suspensão diluída de nanosferas em um filtro de ultra-centrífuga (100 K limite nominal de peso molecular). </li><li> Centrifuga-se o filtro / frasco a 4.500 x g durante 2 minutos ou até que só uma pequena quantidade e permanecem na câmara de filtro. </li></ol></li><li> Ressuspender o nanosferas em cerca de 1 ml de água desionizada (DI) de água de modo a que a concentração das nanopartículas é 10 13 partículas / ml. A suspensão é estável durante várias horas, uma vez ressuspensas em água DI. <ol><li> Verifique a densidade de número e confirmar as nanopartículas hanão tenho agregado. Dilui-se a suspensão de nanopartículas concentrado por um factor de 1:10 de volta para a concentração original, colocando 0,150 ml da suspensão numa cuvete (1 cm de percurso), e a esta adicionar 1,35 ml de água DI. </li><li> Coloque a cuvete um espectrómetro e medir o espectro de absorção da suspensão e a suspensão inicial. Compare a posição de pico e largura à meia altura para garantir agregação não ocorreu. A magnitude dos picos de absorvância para ambas as amostras devem ser, aproximadamente, a mesma, garantindo, assim, a amostra concentrada é mais denso por um factor de 10. </li></ol></li><li> Em um frasco de vidro limpo de 20 ml de borosilicato separado adicionar 1 ml de tetrahidrofurano (THF). </li><li> Adicionar os ligandos tiol-alcano (por exemplo, 5 ml de 1,6-hexanoditiol e 5 ml de 1-dodecanotiol) ao THF e agitar a solução para misturar uniformemente. Ligando suficiente deve ser adicionado para cobrir, pelo menos, toda a área de superfície das nanopartículas em suspensão. Excess ligante aumenta a velocidade ea eficiência da reação. </li><li> Em uma coifa, despeje o conteúdo do frasco contendo as nanoesferas de ouro no frasco de THF-ligantes. </li><li> Rapidamente parafuso na tampa e agite o frasco vigorosamente por 15 segundos. </li><li> Remover a tampa e definir o frasco para baixo, na hotte, Figura 1 (a). Dependendo dos ligandos utilizados, os domínios de películas de nanopartículas de ouro formar rapidamente na interface ar-líquido, a Figura 1 (c). Os filmes irá então começar a traduzir-se os lados do tubo, A Figura 1 (d). Quase todas as nanopartículas são cobertas com tiol-ligando, removida a partir da suspensão, e transportados para os lados do frasco para dentro de 1 h, a Figura 1 (e). </li></ol> 2. Transferir as monocamadas sobre substratos removíveis <ol><li> Para transferir as películas no vidro removível e substratos de bolacha de silício: cortar o substrato em uma área de 12,5 milímetros x 25,4 milímetros usando umcaneta traçagem / roda. <ol><li> Os substratos de vidro: limpo usando uma lavagem com acetona, seguido por uma lavagem com álcool isopropílico, e finalmente uma lavagem com água DI. Permita que os substratos para secar, vá para a seção 2.2. </li><li> Silicon Wafer Substratos: em um exaustor preparar solução Piranha (3 partes de ácido sulfúrico concentrado para 1 parte de 30% de peróxido de hidrogênio, CUIDADO: oxidante, corrosivo). Colocar 15 ml de ácido sulfúrico em 20 ml de um frasco de vidro de borosilicato. Para isso adicione lentamente 5 ml de 30% de peróxido de hidrogênio. Não tampar o frasco. Tenha cuidado; a mistura é altamente exotérmica. Veja a referência para mais informações sobre segurança 19. </li><li> Mergulhe cuidadosamente os substratos de wafer de silício em solução Piranha por 30 minutos, retire, lave com água DI e secas com nitrogênio. </li><li> Como passo opcional, o frasco utilizado para a troca de ligando de nanopartículas e de auto-montagem pode ser salinizado para forçar todos os nanopartículas sobre o substrato de vidro ou de SiLicon wafer em vez de as paredes do frasco de vidro, caso contrário, vá para a seção 2.2. </li><li> Encha o frasco de vidro com solução piranha (ATENÇÃO: oxidante, corrosivo), consulte a secção 2.1.2. </li><li> Deixe o frasco de molho por 30 min. Após 30 minutos lave o frasco com água DI. </li><li> Encha frasco com 1% v / v de hexametildissilazano em acetona e tampão. </li><li> Deixe o frasco selado de molho por 24 horas, em seguida, enxágüe com água DI e secas com nitrogênio. </li></ol></li><li> Antes da agitação (secção 1.6) inserir o substrato no interior do frasco. Parafuso na tampa e shake. </li><li> Depois de agitar remover a tampa e, com uma pinça, coloque o substrato quase vertical contra a parede do frasco. </li><li> Usar uma pipeta para revestir a mistura de reacção sobre o substrato. A reacção termina quando todo o solvente orgânico se ter evaporado toda a nanopartícula ou foram removidos a partir da suspensão. </li></ol> 3. Análise monocamada <ol><li> Estimar oeficiência das nanoesferas na monocamada de embalagem rapidamente através da observação da transmissão e as propriedades reflectoras do filme. Iluminar a monocamada sobre substratos de vidro de trás com uma fonte de luz branca. Com uma fonte de luz branca, um filme de cor uniforme devem ser observados para alta densidade de filmes monocamada de nanopartículas na transmissão e uma reflexão ouro-como observado em reflexão, Figura 2. </li><li> Use um espectrômetro (ver secção 1.2.2) para quantificar o espectro de absorção macroscópica das monocamadas, Figura 4. Normalizar o espectro de absorção com uma lâmina de vidro limpa. Monte o filme monocamada, em um substrato de vidro, para o caminho do feixe do espectrômetro e recolher o espectro de absorção. Nota: O pico de absorvância deve ser significativamente vermelho deslocado várias centenas de nanómetros, dependendo do ligando utilizado. O factor de qualidade do pico de absorvância deve ser comparável ao valor da suspensão diluída, mas apenas ligeiramente broadened (Figura 4). Se o pico de absorção é muito amplo ou não bem definida, em seguida, os filmes monocamada são, provavelmente, de má qualidade, vá para a seção 3.3 para posterior caracterização. </li><li> Examinar a organização nanoscopic das nanoesferas, utilizando microscopia electrónica de varrimento (SEM) de monocamadas transferidas para substratos de bolacha de silício (ver secção 2.1.2), como mostrado na Figura 3. Se as películas no vidro são substratos ligar fita condutiva para um canto da película e, triturando-o pedestal SEM para impedir que a carga e permitir imagens. </li></ol> 4. Técnica de Transferência de Fase eficiente para solúveis orgânicos Nanopartículas <ol><li> Para utilizar a técnica como um meio eficaz para funcionalizar as nanopartículas com tiol-ligantes, decantar a solução restante a partir do fundo do frasco, após a reacção estar completa, a secção 1.7, e secar o material no frasco sob azoto. </li><li> Adicionar um solvente orgânico (por exemplo,clorofórmio, tolueno) para re-suspender as nanopartículas com quase 100% de transferência de fase de partículas e de recuperação. </li><li> Repetir a secção 1.2.1 para assegurar que as nanopartículas não agregadas após re-suspensão em solvente orgânico. Se o pico de absorvância é placa, em relação à suspensão inicial, sonicar a amostra durante 15 minutos para ajudar redispersar a nanopartículas, Figura 4. </li></ol>

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Este protocolo descreve um único &quot;one-pot&quot; técnica de automontagem para criar filmes macroscópicos monocamada de nanopartículas-ligante utilizando transferência de fase, separação de fases e gradientes de tensão superficial. A vantagem desta técnica é que ela combina três processos de auto-montagem em um processo único, de baixo custo; através de uma rápida e eficiente transferência de fase as nanopartículas, a montagem das partículas em monocamadas na interface ar-líquido e transportar os fi...

A auto-montagem de filmes de nanopartículas macroscópicas tem atraído muita atenção devido às suas propriedades únicas determinado a partir da geometria e da composição dos elementos 5 e pode conduzir a uma ampla gama de aplicações ópticas, electrónicas e químicas 6-14. Para auto-montar filmes nanopartículas metálicas niveladas com ligantes devem ser embalados em alta densidade, monocamadas. No entanto, vários problemas de montagem precisam ser abordadas para fazer avançar o desenvolvimento deste tipo de materiais. Primeiro, surfactante estabilizado nanopartículas metálicas são tipicamente sintetizados por métodos em química húmida suspensões diluídas 15. Para prevenir a agregação e para controlar o espaçamento interpartículas das nanopartículas em filmes, as nanopartículas têm de ser cobertas com conchas de ligando. Após as nanopartículas têm sido funcionalizado com ligandos as nanopartículas permanecem tipicamente em suspensões relativamente diluídas. A técnica é, em seguida, needed para auto-montar as nanopartículas em macroscópicas, de alta densidade, filmes monocamada 16, 17. 18 fase Cheng et al. Transferido nanobastões de ouro usando poliestireno tiolada em uma suspensão tetra-água. O nanorods, onde, em seguida, re-suspensos em clorofórmio e uma gota foi colocado numa interface ar-água e evaporou-se, lentamente, a formação de películas de monocamada. Bigioni et al. 17 criado monocamadas macroscópicas de dodecanotiol tampado nanoesferas de ouro utilizando o excesso de ligante e rápida evaporação do solvente, mas as nanoesferas precisava ser transferido fase antes de auto-montagem. Uma vez que as películas em monocamada são formados tipicamente eles precisam de ser transportados para um substrato. Mayya et al. 3 nanoesferas confinado em uma interface água-tolueno e transferiu-os em substratos sem modelo usando gradientes de tensão superficial. Da mesma forma, Johnson <em&gt; et al. 4 suspensos nanoesferas de prata em excesso ligante e depois traduzido as nanopartículas até as paredes do frasco utilizando gradientes de tensão superficial de dois fluidos imiscíveis. Embora existam técnicas de montagem para tratar cada uma dessas questões a necessidade de técnicas mais eficientes é necessário para ajudar no desenvolvimento da produção cinematográfica de nanopartículas em grande escala. Aqui demonstramos uma técnica simples e robusta, que combina os três problemas de auto-montagem descrito acima em que uma única técnica de &quot;one-pot&quot;, mostrada na Figura 1. Água Um solvente orgânico miscível (por exemplo, tetra-hidrofurano, sulfóxido de dimeythl), é usado para primeiro rapidamente e eficientemente funcionalizar tiol-ligandos (por exemplo, tiol-alcano, tiol-eno, tiol-fenol) para as nanoparticulas de ouro (por exemplo, nanoesferas, nanorods, etc.) A mistura, em seguida, dirige a auto-montagem das nanopartículas em macroscópico, de alta densidade, monolayer filmes na interface ar-fluido, utilizando a separação das fases. Finalmente, as películas monocamada de nanopartículas formar em substratos isentos de modelo utilizando gradientes de tensão superficial da mistura de água / solvente orgânico, a Figura 2 e Figura 3.

<table border="0" cellpadding="0" cellspacing="0" width="628">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:224px;">1-6 hexanedithiol</td>
			<td style="width:97px;">Sigma</td>
			<td style="width:140px;">H12005-5G</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:224px;">1-dodecanethiol</td>
			<td style="width:97px;">Sigma</td>
			<td style="width:140px;">471364-100ML</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:224px;">20 ml liquid scintillation vials</td>
			<td style="width:97px;">Sigma</td>
			<td style="width:140px;">Z253081-1PAK</td>
			<td></td>
		</tr>
		<tr height="24">
			<td height="24" style="height:25px;width:224px;">acetone</td>
			<td style="width:97px;">Sigma</td>
			<td>650501-1L</td>
			<td></td>
		</tr>
		<tr height="24">
			<td height="24" style="height:24px;width:224px;">amicon ultra-15 centrifugal filter&#160;</td>
			<td style="width:97px;">Millipore</td>
			<td style="width:140px;">100K</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:224px;">centrifuge</td>
			<td style="width:97px;">Sorvall&#160;</td>
			<td style="width:140px;">RC5B</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:224px;">centrifuge&#160;</td>
			<td style="width:97px;">Eppendorf</td>
			<td style="width:140px;">5810R</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:224px;">deionized water&#160;</td>
			<td style="width:97px;">in-house&#39;</td>
			<td style="width:140px;">N/A</td>
			<td></td>
		</tr>
		<tr height="24">
			<td height="24" style="height:25px;width:224px;">glass slides</td>
			<td style="width:97px;">Sigma</td>
			<td style="width:140px;">CLS294875X25-72EA</td>
			<td></td>
		</tr>
		<tr height="24">
			<td height="24" style="height:24px;width:224px;">15 nm gold nanospheres</td>
			<td style="width:97px;">Ted Pella, Inc</td>
			<td style="width:140px;">15703-1</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:224px;">hexamethyldisilazane</td>
			<td style="width:97px;">Sigma</td>
			<td style="width:140px;">52619-50ML</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:224px;">hydrogen peroxide (30%)</td>
			<td style="width:97px;">Sigma</td>
			<td style="width:140px;">216763-100ML</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:224px;">scanning electron microscope</td>
			<td style="width:97px;">Carl Zeiss</td>
			<td style="width:140px;">Model 55</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:224px;">polished silicon wafer</td>
			<td style="width:97px;">Sun Edison</td>
			<td style="width:140px;">N/A</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:224px;">spectrometer</td>
			<td style="width:97px;">OceanOptics</td>
			<td style="width:140px;">USB4000-VIS-NIR</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:224px;">sulfuric acid</td>
			<td style="width:97px;">Fisher</td>
			<td style="width:140px;">A300-212</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:224px;">tetrahydrofuran</td>
			<td style="width:97px;">Sigma</td>
			<td style="width:140px;">401757-100ML</td>
			<td></td>
		</tr>
	</tbody>
</table>

a technique to functionalize and self-assemble macroscopic nanoparticle-ligand monolayer films onto template-free substrates

Este protocolo descreve uma técnica de auto-montagem para criar os filmes monocamada macroscópicas compostas de nanopartículas revestidas com ligando 1, 2. A técnica simples, robusta e escalável functionalizes eficientemente as nanopartículas metálicas com tiol-ligantes em uma mistura de água / solvente orgânico miscível permitindo enxerto rápido de grupos de tiol na superfície das nanopartículas de ouro. Os ligandos hidrófobos nas nanopartículas depois rapidamente fase separar as nanopartículas de suspensão de base aquosa e prendê-los para a interface ar-fluido. Isso leva as nanopartículas cobertas pelo ligante para formar domínios monocamada na interface ar-fluido. O uso de solventes orgânicos miscíveis em água é importante, uma vez que permite que o transporte das nanopartículas da interface em substratos isentos de modelo. O fluxo é mediada por um gradiente de tensão de superfície 3, 4 e cria macroscópico, de alta densidade, nanop monocamadafilmes artigo ligante. Esta técnica de auto-montagem pode ser generalizado para incluir o uso de partículas de diferentes composições, tamanho e forma e pode conduzir a um método de montagem eficiente para produzir filmes de baixo custo, macroscópicas, de alta densidade, de nanopartículas em monocamada para aplicações generalizadas .

A Figura 1 (a) mostra uma suspensão de nanoesferas de ouro, ligandos tiol-alcano, tetrahidrofurano e água num frasco de vidro imediatamente após a mistura. Um diagrama esquemático das três principais etapas de auto-montagem, transferência de fase, a separação de fase, e um gradiente de tensão superficial transporte mediado filme é mostrado na Figura 1 (b) como uma vista expandida na interface ar-líquido, perto da parte lateral do frasco. Os grupos...

Watch this Scientific Journal Video about A Technique to Functionalize and Self-assemble Macroscopic Nanoparticle-ligand Monolayer Films onto Template-free Substrates at JoVE.com

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

Uma técnica simples, robusta e escalável para funcionalizar e auto-montar macroscópicas filmes monocamada de nanopartículas-ligante em substratos sem modelo descrito neste protocolo.

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 ...

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Research

JoVE Journal

Chemistry

10.8K visualizações.  Naval Research Laboratory.  Uma técnica simples, robusta e escalável para funcionalizar e auto-montar macroscópicas filmes monocamada de nanopartículas-ligante em substratos sem modelo descrito neste protocolo. 

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

Covalent Binding of BMP-2 on Surfaces Using a Self-assembled Monolayer Approach

Bone morphogenetic protein 2 (BMP-2) is a growth factor embedded in the extracellular matrix of bone tissue. BMP-2 acts as trigger of mesenchymal cell differentiation into osteoblasts, thus stimulating healing and de novo bone formation. The clinical use of recombinant human BMP-2 (rhBMP-2) in conjunction with scaffolds has raised recent controversies, based on the mode of presentation and the amount to be delivered. The protocol presented here provides a simple and efficient way to deliver BMP-2 for in vitro studies on cells. We describe how to form a self-assembled monolayer consisting of a heterobifunctional linker, and show the subsequent binding step to obtain covalent immobilization of rhBMP-2. With this approach it is possible to achieve a sustained presentation of BMP-2 while maintaining the biological activity of the protein. In fact, the surface immobilization of BMP-2 allows targeted investigations by preventing unspecific adsorption, while reducing the amount of growth factor and, most notably, hindering uncontrolled release from the surface. Both short- and long-term signaling events triggered by BMP-2 are taking place when cells are exposed to surfaces presenting covalently immobilized rhBMP-2, making this approach suitable for in vitro studies on cell responses to BMP-2 stimulation.

We describe a method for accomplishing efficient immobilization of BMP-2 on surfaces. Our approach is based on the formation of a self-assembled monolayer to achieve the covalent binding of BMP-2 via its free amine residues. This method is a useful tool to study signaling at the cell membrane.

A ligação covalente de BMP-2 em superfícies com uma monocamada auto-montada Abordagem

Bone morphogenetic protein 2 (BMP-2) is a growth factor embedded in the extracellular matrix of bone tissue. BMP-2 acts as trigger of mesenchymal cell ...

Química

Towards Biomimicking Wood: Fabricated Free-standing Films of Nanocellulose, Lignin, and a Synthetic Polycation

Woody materials are comprised of plant cell walls that contain a layered secondary cell wall composed of structural polymers of polysaccharides and lignin. Layer-by-layer (LbL) assembly process which relies on the assembly of oppositely charged molecules from aqueous solutions was used to build a freestanding composite film of isolated wood polymers of lignin and oxidized nanofibril cellulose (NFC). To facilitate the assembly of these negatively charged polymers, a positively charged polyelectrolyte, poly(diallyldimethylammomium chloride) (PDDA), was used as a linking layer to create this simplified model cell wall. The layered adsorption process was studied quantitatively using quartz crystal microbalance with dissipation monitoring (QCM-D) and ellipsometry. The results showed that layer mass/thickness per adsorbed layer increased as a function of total number of layers. The surface coverage of the adsorbed layers was studied with atomic force microscopy (AFM). Complete coverage of the surface with lignin in all the deposition cycles was found for the system, however, surface coverage by NFC increased with the number of layers. The adsorption process was carried out for 250 cycles (500 bilayers) on a cellulose acetate (CA) substrate. Transparent free-standing LBL assembled nanocomposite films were obtained when the CA substrate was later dissolved in acetone. Scanning electron microscopy (SEM) of the fractured cross-sections showed a lamellar structure, and the thickness per adsorption cycle (PDDA-Lignin-PDDA-NC) was estimated to be 17 nm for two different lignin types used in the study. The data indicates a film with highly controlled architecture where nanocellulose and lignin are spatially deposited on the nanoscale (a polymer-polymer nanocomposites), similar to what is observed in the native cell wall.

The objective of this research was to form synthetic plant cell wall tissue using layer-by-layer assembly of nanocellulose fibrils and isolated lignin assembled from dilute aqueous suspensions.&#160; Surface measurement techniques of quartz crystal microbalance and atomic force microscopy were used to monitor the formation of the polymer-polymer nanocomposite material.

Rumo Biomimicking Madeira: Fabricados free-standing Filmes de nanocellulose, lignina, e uma policátion sintético

Woody materials are comprised of plant cell walls that contain a layered secondary cell wall composed of structural polymers of polysaccharides and ...

Atomically Defined Templates for Epitaxial Growth of Complex Oxide Thin Films

Atomically defined substrate surfaces are prerequisite for the epitaxial growth of complex oxide thin films. In this protocol, two approaches to obtain such surfaces are described. The first approach is the preparation of single terminated perovskite SrTiO3 (001) and DyScO3 (110) substrates. Wet etching was used to selectively remove one of the two possible surface terminations, while an annealing step was used to increase the smoothness of the surface. The resulting single terminated surfaces allow for the heteroepitaxial growth of perovskite oxide thin films with high crystalline quality and well-defined interfaces between substrate and film. In the second approach, seed layers for epitaxial film growth on arbitrary substrates were created by Langmuir-Blodgett (LB) deposition of nanosheets. As model system Ca2Nb3O10- nanosheets were used, prepared by delamination of their layered parent compound HCa2Nb3O10. A key advantage of creating seed layers with nanosheets is that relatively expensive and size-limited single crystalline substrates can be replaced by virtually any substrate material.

Various procedures are outlined to prepare atomically defined templates for epitaxial growth of complex oxide thin films. Chemical treatments of single crystalline SrTiO3 (001) and DyScO3 (110) substrates were performed to obtain atomically smooth, single terminated surfaces. Ca2 Nb3 O10- nanosheets were used to create atomically defined templates on arbitrary substrates.

Templates atomicamente definidos para crescimento epitaxial do Complexo Óxido Filmes Finos

Atomically defined substrate surfaces are prerequisite for the epitaxial growth of complex oxide thin films. In this protocol, two approaches to obtain ...

Fabrication of Large-area Free-standing Ultrathin Polymer Films

This procedure describes a method for the fabrication of large-area and ultrathin free-standing polymer films. Typically, ultrathin films are prepared using either sacrificial layers, which may damage the film or affect its mechanical properties, or they are made on freshly cleaved mica, a substrate that is difficult to scale. Further, the size of ultrathin film is typically limited to a few square millimeters. In this method, we modify a surface with a polyelectrolyte that alters the strength of adhesion between polymer and deposition substrate. The polyelectrolyte can be shown to remain on the wafer using spectroscopy, and a treated wafer can be used to produce multiple films, indicating that at best minimal amounts of the polyelectrolyte are added to the film. The process has thus far been shown to be limited in scalability only by the size of the coating equipment, and is expected to be readily scalable to industrial processes. In this study, the protocol for making the solutions, preparing the deposition surface, and producing the films is described.

We describe a method for the fabrication of large-area (up to 13 cm diameter) and ultrathin (as thin as 8 nm) polymer films. Instead of using a sacrificial interlayer to delaminate the film from its substrate, we use a self-limiting surface treatment suitable for arbitrarily large areas.

Fabricação de grande-área royalty-pé ultrafinos Polymer Films

This procedure describes a method for the fabrication of large-area and ultrathin free-standing polymer films.  Typically, ultrathin films are prepared ...

Preparation of Mica and Silicon Substrates for DNA Origami Analysis and Experimentation

The designed nature and controlled, one-pot synthesis of DNA origami provides exciting opportunities in many fields, particularly nanoelectronics. Many of these applications require interaction with and adhesion of DNA nanostructures to a substrate. Due to its atomically flat and easily cleaned nature, mica has been the substrate of choice for DNA origami experiments. However, the practical applications of mica are relatively limited compared to those of semiconductor substrates. For this reason, a straightforward, stable, and repeatable process for DNA origami adhesion on derivatized silicon oxide is presented here. To promote the adhesion of DNA nanostructures to silicon oxide surface, a self-assembled monolayer of 3-aminopropyltriethoxysilane (APTES) is deposited from an aqueous solution that is compatible with many photoresists. The substrate must be cleaned of all organic and metal contaminants using Radio Corporation of America (RCA) cleaning processes and the native oxide layer must be etched to ensure a flat, functionalizable surface. Cleanrooms are equipped with facilities for silicon cleaning, however many components of DNA origami buffers and solutions are often not allowed in them due to contamination concerns. This manuscript describes the set-up and protocol for in-lab, small-scale silicon cleaning for researchers who do not have access to a cleanroom or would like to incorporate processes that could cause contamination of a cleanroom CMOS clean bench. Additionally, variables for regulating coverage are discussed and how to recognize and avoid common sample preparation problems is described.

Reproducible cleaning processes for substrates used in DNA origami research are described, including bench-top RCA cleaning and derivatization of silicon oxide. Protocols for surface preparation, DNA origami deposition, drying parameters, and simple experimental set-ups are illustrated.

Preparação de Mica e silício substratos para análise do DNA Origami e Experimentação

The designed nature and controlled, one-pot synthesis of DNA origami provides exciting opportunities in many fields, particularly nanoelectronics. Many of ...

Cooling Rate Dependent Ellipsometry Measurements to Determine the Dynamics of Thin Glassy Films

This report aims to fully describe the experimental technique of using ellipsometry for cooling rate dependent Tg (CR-Tg) experiments. These measurements are simple high-throughput characterization experiments, which can determine the glass transition temperature (Tg), average dynamics, fragility and the expansion coefficient of the super-cooled liquid and glassy states for a variety of glassy materials. This technique allows for these parameters to be measured in a single experiment, while other methods must combine a variety of different techniques to investigate all of these properties. Measurements of dynamics close to Tg are particularly challenging. The advantage of cooling rate dependent Tg measurements over other methods which directly probe bulk and surface relaxation dynamics is that they are relatively quick and simple experiments, which do not utilize fluorophores or other complicated experimental techniques. Furthermore, this technique probes the average dynamics of technologically relevant thin films in temperature and relaxation time (&#964;&#945;) regimes relevant to the glass transition (&#964;&#945; &#62; 100 sec). The limitation to using ellipsometry for cooling rate dependent Tg experiments is that it cannot probe relaxation times relevant to measurements of viscosity (&#964;&#945; &#60;&#60; 1 sec). Other cooling rate dependent Tg measurement techniques, however, can extend the CR-Tg method to faster relaxation times. Furthermore, this technique can be used for any glassy system so long as the integrity of the film remains throughout the experiment.

Here, we present a protocol for cooling rate dependent ellipsometry experiments, which can determine the glass transition temperature (Tg), average dynamics, fragility and the expansion coefficient of the super-cooled liquid and glass for a variety of glassy materials.

Arrefecimento Medidas de freqüência Elipsometria Dependentes para determinar a dinâmica de finas Glassy Films

This report aims to fully describe the experimental technique of using ellipsometry for cooling rate dependent Tg (CR-Tg) experiments. These measurements ...

Deacetylation Assays to Unravel the Interplay between Sirtuins (SIRT2) and Specific Protein-substrates

Acetylation has emerged as an important post-translational modification (PTM) regulating a plethora of cellular processes and functions. This is further supported by recent findings in high-resolution mass spectrometry based proteomics showing that many new proteins and sites within these proteins can be acetylated. However the identity of the enzymes regulating these proteins and sites is often unknown. Among these enzymes, sirtuins, which belong to the class III histone lysine deacetylases, have attracted great interest as enzymes regulating the acetylome under different physiological or pathophysiological conditions. Here we describe methods to link SIRT2, the cytoplasmic sirtuin, with its substrates including both in vitro and in vivo deacetylation assays. These assays can be applied in studies focused on other members of the sirtuin family to unravel the specific role of sirtuins and are necessary in order to establish the regulatory interplay of specific deacetylases with their substrates as a first step to better understand the role of protein acetylation. Furthermore, such assays can be used to distinguish functional acetylation sites on a protein from what may be non-regulatory acetylated lysines, as well as to examine the interplay between a deacetylase and its substrate in a physiological context.

Deacetylation Assays to Unravel the Interplay between Sirtuins SIRT2 and Specific Protein-substrates

This protocol describes the required steps to execute in vitro and in vivo deacetylation assays in order to establish the role of proteins as specific deacetylation substrates for sirtuins and further study the role of reversible - lysine acetylation as a post-translational modification.

Desacetilação Ensaios para desvendar a interação entre Sirtuins (SIRT2) e Proteína-substratos específicos

Acetylation has emerged as an important post-translational modification (PTM) regulating a plethora of cellular processes and functions. This is further ...

Capillary Electrophoresis to Monitor Peptide Grafting onto Chitosan Films in Real Time

Free-solution capillary electrophoresis (CE) separates analytes, generally charged compounds in solution through the application of an electric field. Compared to other analytical separation techniques, such as chromatography, CE is cheap, robust and effectively requires no sample preparation (for a number of complex natural matrices or polymeric samples). CE is fast and can be used to follow the evolution of mixtures in real time (e.g., chemical reaction kinetics), as the signals observed for the separated compounds are directly proportional to their quantity in solution.
Here, the efficiency of CE is demonstrated for monitoring the covalent grafting of peptides onto chitosan films for subsequent biomedical applications. Chitosan&#39;s antimicrobial and biocompatible properties make it an attractive material for biomedical applications such as cell growth substrates. Covalently grafting the peptide RGDS (arginine - glycine - aspartic acid - serine) onto the surface of chitosan films aims at improving cell attachment. Historically, chromatography and amino acid analysis have been used to provide a direct measurement of the amount of grafted peptide. However, the fast separation and absence of sample preparation provided by CE enables equally accurate yet real-time monitoring of the peptide grafting process. CE is able to separate and quantify the different components of the reaction mixture: the (non-grafted) peptide and the chemical coupling agents. In this way the use of CE results in improved films for downstream applications.
The chitosan films were characterized through solid-state NMR (nuclear magnetic resonance) spectroscopy. This technique is more time-consuming and cannot be applied in real time, but yields a direct measurement of the peptide and thus validates the CE technique.

Free solution capillary electrophoresis is a fast, cheap and robust analytical method that enables the quantitative monitoring of chemical reactions in real time. Its utility for rapid, convenient and precise analysis is demonstrated here through analysis of covalent peptide grafting onto chitosan films for improved cell adhesion.

Eletroforese Capilar para monitorar Peptide Enxertia em quitosana Films em Tempo real

Free-solution capillary electrophoresis (CE) separates analytes, generally charged compounds in solution through the application of an electric field. ...

Reactive Vapor Deposition of Conjugated Polymer Films on Arbitrary Substrates

We demonstrate a method of conformally coating conjugated polymers on arbitrary substrates using a custom-designed, low-pressure reaction chamber. Conductive polymers, poly(3,4-ethylenedioxythiophene) (PEDOT) and poly(3,4-propylenedioxythiophene) (PProDOT), and a semiconducting polymer, poly(thieno[3,2-b]thiophene) (PTT), were deposited on unconventional highly-disordered and textured substrates with high surface areas, such as paper, towels and fabrics. This reported deposition chamber is an improvement of previous vapor reactors because our system can accommodate both volatile and nonvolatile monomers, such as 3,4-propylenedioxythiophene and thieno[3,2-b]thiophene. Utilization of both solid and liquid oxidants are also demonstrated. One limitation of this method is that it lacks sophisticated in situ thickness monitors. Polymer coatings made by the commonly used solution-based coating methods, such as spin-coating and surface grafting, are often not uniform or susceptible to mechanical degradation. This reported vapor phase deposition method overcomes those drawbacks and is a strong alternative to common solution-based coating methods. Notably, polymer films coated by the reported method are uniform and conformal on rough surfaces, even at a micrometer scale. This feature allows for future application of vapor deposited polymers in electronics devices on flexible and highly textured substrates.

This paper presents a protocol for reactive vapor deposition of poly(3,4-ethylenedioxythiophene), poly(3,4-propylenedioxythiophene), and poly(thieno[3,2-b]thiophene) films on glass slides and rough substrates, such as textiles and paper.

Depósito de Vapor reativa dos filmes de polímeros conjugados em substratos arbitrários

We demonstrate a method of conformally coating conjugated polymers on arbitrary substrates using a custom-designed, low-pressure reaction chamber. ...

Solution-Processed "Silver-Bismuth-Iodine" Ternary Thin Films for Lead-Free Photovoltaic Absorbers

Bismuth-based hybrid perovskites are regarded as promising photo-active semiconductors for environment-friendly and air-stable solar cell applications. However, poor surface morphologies and relatively high bandgap energies have limited their potential. Silver-bismuth-iodine (Ag-Bi-I) is a promising semiconductor for optoelectronic devices. Therefore, we demonstrate the fabrication of Ag-Bi-I ternary thin films using material solution processing. The resulting thin films exhibit controlled surface morphologies and optical bandgaps according to their thermal annealing temperatures. In addition, it has been reported that Ag-Bi-I ternary systems crystallize to AgBi2I7, Ag2BiI5, etc. according to the ratio of the precursor chemicals. The solution-processed AgBi2I7 thin films exhibit a cubic-phase crystal structure, dense, pinhole-free surface morphologies with grains ranging in size from 200 to 800 nm, and an indirect bandgap of 1.87 eV. The resultant AgBi2I7 thin films show good air stability and energy band diagrams, as well as surface morphologies and optical bandgaps suitable for lead-free and air-stable single-junction solar cells. Very recently, a solar cell with 4.3% power conversion efficiency was obtained by optimizing the Ag-Bi-I crystal compositions and solar cell device architectures.

Solution-Processed &quot;Silver-Bismuth-Iodine&quot; Ternary Thin Films for Lead-Free Photovoltaic Absorbers

Herein, we present detailed protocols for solution-processed silver-bismuth-iodine (Ag-Bi-I) ternary semiconductor thin films fabricated on TiO2-coated transparent electrodes and their potential application as air-stable and lead-free optoelectronic devices.

Solução-processados "Prata-bismuto-iodo" ternário filmes finos para absorventes de chumbo fotovoltaicos

Bismuth-based hybrid perovskites are regarded as promising photo-active semiconductors for environment-friendly and air-stable solar cell applications. ...