Este trabalho foi apoiado por Ogden Faculdade de Ciências e Engenharia, incluindo suporte interno do Departamento de Química e do Escritório de Investigação (PACR 13-8032) da Western Kentucky University. A assistência do Dr. John Andersland no Centro de Microscopia WKU (MEV) e Professor Associado Yan Cao do Instituto WKU para Ciência de Combustão e Engenharia (análise BET) tem sido fundamental para a realização deste trabalho.

1. Preparação da Emulsão <ol><li> Índice de emulsão <ol><li> Massa uma quantidade adequada de sal para produzir 10 ml de solução de 0,03-M. Para platina (IV) medida cloreto de 0,101 g, para o zinco (II) cloreto (ZnCl2) medida 0,032 g, e cloreto de sódio (NaCl) medida 0,018 g. </li><li> Em tubos de ensaio individuais, cada dissolver o sal em 10 ml de água Dl. Reservada para uso posterior. </li><li> Utilize a 20 mL, frasco de vidro selado para o conteúdo ao longo deste procedimento. Tare um equilíbrio para o frasco de vidro. </li><li> Pesar polidimetilsiloxano terminado em vinilo por lentamente despejando-a sobre uma haste de agitação e para dentro do frasco de vidro que descansa na escala zerada. Pesar 1,02 g (equivalente a 1.080 mL). Nota: A elevada viscosidade deste polímero torna impraticável pipetagem. </li><li> Pipetar 1,02 ml de n-heptano para o frasco. Adicionar 2 gotas de agente tensioactivo não iónico (monooleato de sorbitano) ao frasco. Pipetar 0,3 ml de solução salina e 0,45 ml de di-água ao frasco. </li><li> Selar o frasco de vidro por estragar a tampa firmemente. Agita-se vigorosamente durante 60 segundos para iniciar a emulsão antes de iniciar sonicação. </li></ol></li><li> Construção de água-banho Sonicator Aparelho <ol><li> Preencha sonicador com água até a linha de preenchimento mínimo. Adicione 250 ml de água da torneira para um copo de 400 ml. Encha o copo de 400 ml com gelo, de modo que o nível da água é apenas na borda. </li><li> Coloque este recipiente no interior do banho de água sonicador. Verifique a linha de preenchimento-no sonicator, ajustando, se necessário. Coloque um anel de ficar junto ao banho-maria sonicator. </li><li> Usando dois anel de suporte grampos, posicioná-los de modo a que o braço se estende para fora, perpendicularmente ao anel de suporte e uma outra está estendido para o banho de água de modo que está a apontar para baixo para dentro do copo cheio com água gelada. Anexar outro grampo para o anel de suporte com um termómetro para baixo no copo de 400 ml de modo a que a temperatura pode ser monitorizada ao longo de sonicação. </li></ol></li><li> Emulsificação Procedimento <ol><li> Colocar o frasco contendo emulsão de modo que ele é inteiramente submerso no copo de 400 ml, ao garantir que na braçadeira saliente para dentro da proveta. </li><li> Assegure-se que o frasco de vidro contendo a mistura de PDMS não estiver em contacto com as paredes do copo para eliminar o calor provocado pelo atrito. </li><li> Ligue o sonicator e definir o tempo de ultra-sons durante 7 min. Uma vez que a emulsão é muito sensível ao calor, assegurar que a temperatura no interior da taça é entre 0 e 5 ° C ao longo de sonicação. Comece sonicação uma vez que a temperatura no interior do copo é desejável. </li><li> Após 7 minutos de ultra-sons, remover o frasco e agitar suavemente / redemoinho durante 1 min, mantendo a parte superior do frasco para eliminar quaisquer aglomerados que possam formar na emulsão. </li><li> Elimine o conteúdo da proveta. Recarga com 250 ml de água e adicionar gelo ao preenchimento para dentro de 1 cm do topo do copo. </li><li> Coloque o frasco de volta no gancho metálico. Mergulhe-o sob a água gelada para resume ultra-sons durante 7 min. </li><li> Repita os passos 1.3.3 a 1.3.6 para um total de oito períodos de sonicação, 7-mínimo, ou até que a sonicação parece ser homogénea e sem aglomerados estão presentes. Armazenar à temperatura ambiente. NOTA: A emulsificação deve ser estável durante vários dias, mas pode ser recuperado por sonicação como acima em intervalos de 7 min até que apareça homogénea. Armazenar à temperatura ambiente. </li></ol></li></ol> 2. A reticulação <ol><li> Instalação para Adição de trietoxissilano / Solução surfactante <ol><li> Pipetar 5,4 ml trietoxissilano num tubo de ensaio. Coloque em um rack de tubo de ensaio sob o capô para uso posterior. </li><li> Encha um copo de 400 ml com água gelada e coloque-o sob o capô. Próximo ao local copo de 400 ml um anel de ficar com uma braçadeira anexado, estendido diretamente sobre a abertura do copo. Este será o banho de gelo durante a adição de silano. </li><li> Colocar uma placa quente sobre o outro lado do anel de suporte. Encha um copo de 800 ml com cerca de 700 ml deagua de torneira. Coloque-o sobre a placa de aquecimento. </li><li> Ligue a placa quente e manter uma temperatura de 75 a 85 ° C no interior do copo de 800 ml. Anexar uma braçadeira com um termómetro para o suporte anelar de modo que a temperatura da água dentro da proveta de 800 ml, pode ser monitorizada. </li><li> Produzir a solução de agente tensioactivo por dissolução de 0,5 g de sulfato de dodecilo de sódio a 375 ml de água (4,62 mm). Adicionar cerca de 10 ml de solução de surfactante a um tubo de ensaio limpo vazio. </li><li> Anexar outro grampo para o anel de suporte sob o capô com o tubo de ensaio surfactante fixadas de modo que o seu nível de líquido está abaixo da superfície da água dentro da proveta de 800 ml. Permita 10 minutos para o equilíbrio térmico. </li><li> Molhar um pedaço de papel de filtro e colocá-lo no topo de um pequeno funil. Coloque a haste do funil para dentro de um balão de Erlenmeyer de 250 ml e colocar o balão sob o capô. </li></ol></li><li> A adição de silano <ol><li> Coloque o frasco de emulsão no grampo sobre o gelo-água bicoer no interior do exaustor. Coloque a mistura de PDMS na pinça de modo que o conteúdo do frasco estão abaixo da superfície da água. A adição do silano provoca uma reacção exotérmica, portanto, a emulsão deve ser mantido frio, a fim de manter a sua estrutura. </li><li> Remover a tampa do frasco de vidro para evitar a acumulação gasoso. </li><li> Lentamente o tubo de ensaio contendo silano para dentro do frasco de vidro numa corrente contínua durante um período de cerca de 10 seg (cerca de 0,5 ml / seg). ATENÇÃO: A adição de silano inicia uma reacção exotérmica e a libertação de cloreto de hidrogénio cáustico (HCl) de gás. O frasco vai se tornar extremamente quente e um gás tóxico irá evoluir a partir da mistura. Não mexa o conteúdo ao adicionar o silano. </li><li> Depois de adicionar trietoxissilano completamente, mexa delicadamente o conteúdo com uma haste de agitação de vidro, enquanto vestindo uma luva de proteção de calor. Aguarde 2 min ou até paradas de gás evolução do frasco. </li><li> Folldevido a reticulação, não há separação de fases visível na amostra. Se aglomerados estão presentes, selar o frasco e agite durante 20 segundos rigorosamente, mantendo o frasco pela tampa. </li></ol></li><li> Produção Bead <ol><li> Use, uma pipeta de Pasteur de vidro limpo para desenhar a emulsão reticulada a partir do frasco de vidro. Adicionar a emulsão reticulada gota a gota à solução de tensioactivo (o qual deve ser mantida entre 75 e 85 ° C) para dentro do tubo de ensaio, tendo o mínimo de tempo possível de entre as gotas. </li><li> 30 seg 1 min depois da adição da emulsão, a solução de agente tensioactivo irá começar a desenvolver-se lentamente o gás como os sólidos comecem a formar-se dentro do tubo de ensaio. </li><li> Enquanto vestindo luvas de protecção térmica, pegue o tubo de ensaio fora da braçadeira e despeje todo o seu conteúdo para o aparelho de filtração sob o capô. Filtrar durante 5 min. Remover o papel de filtro a partir do filtro. </li><li> Transfira os sólidos filtrados em um vidro de relógio e pérolas separadas para O / N secagem sob o hood. Limpeza das esferas pode ser adiada indefinidamente. Loja grânulos à TA seco num frasco de vidro selado até ser necessário, e limpo imediatamente antes da utilização. </li></ol></li><li> Bead Limpeza <ol><li> Criar um outro aparelho de filtração sob o capô e colocar as pérolas secas dentro do funil na parte superior do papel de filtro. </li><li> Use um frasco de lavagem de plástico cheio de DI-água para enxaguar as contas suavemente, movendo-os ligeiramente para garantir que todas as contas são lavados. </li><li> Deixe as contas secar durante 1 hora, colocando-os em um vidro de relógio sob o capô. Utilizar um frasco de lavagem cheio com hexanos para enxaguar os grânulos utilizando o mesmo método para a lavagem com água. </li><li> Coloque as contas em um vidro de relógio. Coloque o vidro de relógio e as contas sob o capô para secar. </li><li> Depois as contas estão completamente secos, coloque-os em um pequeno frasco de vidro selado e armazenar a RT para uso futuro. </li></ol></li><li> Montagem dos grânulos para análise em MEV e SEM Configurações <ol><li> Coloque uma tira de afazeresfita condutiva uble lados de carbono na parte superior do topo para o qual os grânulos irão ser montadas. Com uma tesoura, cortar ao redor do topo para garantir que não trava fita sobre as bordas. </li><li> Coloque um pedaço de papel de filtro sob a ponta sobre uma superfície plana. Remover a camada superior da fita de modo que a parte inferior de adesivo é exposto. </li><li> Delicadamente despeje os grânulos sobre o topo. Algumas pérolas vai ficar com a fita, mas a maioria vai saltar fora e terra sobre o papel de filtro. Derrame-los de volta para o frasco se ficassem no papel de filtro. Repita, se necessário, lavando todas as pérolas (de acordo com 2.4.2 a 2.4.5) que se tornam contaminados. </li><li> Para garantir as contas estão seguros no canhoto, use uma seringa e levemente soprar muito estreitamente à superfície do topo. Despeje mais contas sobre o stub, se apenas alguns aderida à fita. Certifique-se de que todas as contas são seguros antes de colocar o stub para a câmara de SEM e evacuando-lo. </li><li> Uma vez que as amostras foram montadas adequadamente eles já estão prontos para sofrer SEM analysis 15. Coletar imagens no modo LOW VAC em 15 keV para optimizar a resolução das características da superfície do talão. </li></ol></li></ol>

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The authors have nothing to disclose.

Os grânulos produzidos utilizando este protocolo (e ajustando a concentração de eletrólitos e identidade) são fundamentalmente diferentes daquelas produzidas com uma emulsão de baixa força iónica, como pode ser visto através da comparação das Figura 1A a outras imagens SEM na Figura 1. Nosso relatório inicial usado PtCl 4, com a intenção de catalisar a polimerização ulterior reticulação na interface aquosa-14 alifático. Nesse relatório, grandes ...

Polydimethylsiloxane (PDMS) is one of the most widely used silicone compounds. Its biocompatibility has led to widespread use in implant and other biomedical engineering structures1,2. It is trivially cross-linked into elastic structures using an organosilyl compound (such as triethoxysilane), a simple and reliable procedure which has made it useful for cast polymer applications where some flexibility is required3. Once cross-linked, PDMS is largely inert, particularly in biological conditions, and is therefore useful for a variety of food and medical applications4,5. Ease of casting, chemical inertness, and hydrophobicity have made it a natural choice for microfluidic devices6,7. Its affinity for non-halogenated, non-polar organic compounds has made it a popular stationary phase in separations chemistry8-10. 
Recently, microbubble fabrications have been used to generate porous beads for use as catalyst structural substrates or in chemical separations11,12. In both applications, ideal materials will have a maximized surface-area-to-volume (SAV) ratio for best efficiency. In a microbubble fabrication process, microstructuring of materials is typically accomplished by isolating the polymer in aliphatic &#8220;microbubbles&#8221; by emulsification in an aqueous continuous phase. The initial report of microporous PDMS beads produced them by mechanical emulsification of two phases (aliphatic and aqueous)13. The stock PDMS liquid (and its cross-linking agent) is dissolved into the aliphatic phase, which is structured into microscopic beads by being forced to cavitate within the (continuous) aqueous phase. The emulsification is stabilized by the addition of a non-ionic surfactant. When the emulsion is added dropwise to a heated bath, solid beads form by agglomeration of the microbubbles into clusters of tiny spheres of cross-linked PDMS. Our goal in this protocol is to modify this procedure to develop beads with an inverted porosity to improve the SAV ratio of the material.
As reported previously, control of the beads can be directed to some extent by the aliphatic:aqueous ratios in the emulsion. However, we have reported recently that addition of platinum(IV) chloride (PtCl4) inverts the porosity: materials are formed in which the PDMS is riddled with concave pores14. This indicates that the aqueous layer cavitates inside the aliphatic one, despite having similar aliphatic:aqueous ratios to those published in the original work13. The primary advantage of our method is that this concave porosity should naturally result in an increased SAV ratio, and thus, improved efficiency for analytical chemistry applications. While we are continuing to explore the specific effects of the addition of the platinum compound, we show here that the same effect can be accomplished using any aqueously soluble ionic compound, though perhaps to a reduced extent. Because our techniques also differ in some key aspects from what has been previously reported, we present our protocols here as a video to encourage others to extend our methods. Most notably, we use a common bath sonicator of the type used to clean glassware or other equipment, rather than the (considerably more expensive) probe sonicator often used in microbubble fabrication. This adjusted approach to the microbubble fabrication procedure could potentially be extended for the production of large quantities of bulk materials as well, creating porous sheets or slabs which could have applications for biomedical devices, aerospace and automotive industry, or substrates for chemical catalysis. Users seeking to generate high-SAV-ratio, microstructured materials using other similar polymers for such analyses may find that our protocols can be extended to any polymer for which the microbubble emulsion technique can be applied.

<table border="0">
	<tbody>
		<tr>
			<td>Poly(dimethylsiloxane), vinyl terminated</td>
			<td>Sigma-Aldrich</td>
			<td>68083-19-2</td>
			<td></td>
		</tr>
		<tr>
			<td>n-Heptane</td>
			<td>Sigma-Aldrich</td>
			<td>142-82-5</td>
			<td>Flammable</td>
		</tr>
		<tr>
			<td>Triethoxysilane</td>
			<td>Sigma-Aldrich</td>
			<td>998-30-1</td>
			<td>Flammable, Accutely Toxic</td>
		</tr>
		<tr>
			<td>Sorbitan Monoleate (Span-80)</td>
			<td>Fluker</td>
			<td>1338-43-8</td>
			<td></td>
		</tr>
		<tr>
			<td>Platinum (IV) Chloride</td>
			<td>Sigma-Aldrich</td>
			<td>13454-96-1</td>
			<td>Accutely Toxic</td>
		</tr>
		<tr>
			<td>Zinc (II) Chloride</td>
			<td>Sigma-Aldrich</td>
			<td>7646-85-7</td>
			<td></td>
		</tr>
		<tr>
			<td>Sodium Chloride</td>
			<td>Sigma-Aldrich</td>
			<td>7647-14-5</td>
			<td></td>
		</tr>
		<tr>
			<td>2.8L Water Bath Sonicator</td>
			<td>VWR</td>
			<td>97043-964</td>
			<td></td>
		</tr>
	</tbody>
</table>

microbubble fabrication of concave-porosity pdms beads

Microbubble fabrication (by use of a fine emulsion) provides a means of increasing the surface-area-to-volume (SAV) ratio of polymer materials, which is particularly useful for separations applications. Porous polydimethylsiloxane (PDMS) beads can be produced by heat-curing such an emulsion, allowing the interface between the aqueous and aliphatic phases to mold the morphology of the polymer. In the procedures described here, both polymer and crosslinker (triethoxysilane) are sonicated together in a cold-bath sonicator. Following a period of cross-linking, emulsions are added dropwise to a hot surfactant solution, allowing the aqueous phase of the emulsion to separate, and forming porous polymer beads. We demonstrate that this method can be tuned, and the SAV ratio optimized, by adjusting the electrolyte content of the aqueous phase in the emulsion. Beads produced in this way are imaged with scanning electron microscopy, and representative SAV ratios are determined using Brunauer&#8211;Emmett&#8211;Teller (BET) analysis. Considerable variability with the electrolyte identity is observed, but the general trend is consistent: there is a maximum in SAV obtained at a specific concentration, after which porosity decreases markedly.

Imagens representativas de SEM de grânulos resultantes a partir de emulsões com diferentes condições electrolíticas são mostrados na Figura 1. A Figura 1A mostra um grânulo semelhantes aos obtidos por Dufaud, et al. 13, produzido utilizando os nossos procedimentos, sem a adição de qualquer electrólito. Grânulos mostrado na Figura 1B-D, resultando em diferentes morfologias para cada ião de metal. Para todas as imagens apre...

Watch this Scientific Journal Video about Microbubble Fabrication of Concave-porosity PDMS Beads at JoVE.com

Microbubble Fabrication of Concave-porosity PDMS Beads

Procedures used to generate microstructured concave-porosity polydimethylsiloxane beads are presented. Effects of electrolyte concentration and identity within the aqueous phase are particularly emphasized.

Fabricação de microbolhas de Côncavo-porosidade Beads PDMS

Microbubble fabrication (by use of a fine emulsion) provides a means of increasing the surface-area-to-volume (SAV) ratio of polymer materials, which is ...

microbubble-fabrication-of-concave-porosity-pdms-beads

Research

JoVE Journal

Chemistry

8.2K visualizações.  Western Kentucky University. Procedures used to generate microstructured concave-porosity polydimethylsiloxane beads are presented. Effects of electrolyte concentration and identity within the aqueous phase are particularly emphasized. 

Vídeo: Microbubble Fabrication of Concave-porosity PDMS Beads

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 ...

Química

Flow-pattern Guided Fabrication of High-density Barcode Antibody Microarray

Antibody microarray as a well-developed technology is currently challenged by a few other established or emerging high-throughput technologies. In this report, we renovate the antibody microarray technology by using a novel approach for manufacturing and by introducing new features. The fabrication of our high-density antibody microarray is accomplished through perpendicularly oriented flow-patterning of single stranded DNAs and subsequent conversion mediated by DNA-antibody conjugates. This protocol outlines the critical steps in flow-patterning DNA, producing and purifying DNA-antibody conjugates, and assessing the quality of the fabricated microarray. The uniformity and sensitivity are comparable with conventional microarrays, while our microarray fabrication does not require the assistance of an array printer and can be performed in most research laboratories. The other major advantage is that the size of our microarray units is 10 times smaller than that of printed arrays, offering the unique capability of analyzing functional proteins from single cells when interfacing with generic microchip designs. This barcode technology can be widely employed in biomarker detection, cell signaling studies, tissue engineering, and a variety of clinical applications.

This protocol outlines the fabrication of a large-scale, multiplexed two-dimensional DNA or antibody array, with potential applications in cell signaling studies and biomarker detection.

Flow-padrão Fabrication guiada de alta densidade Barcode Antibody Microarray

Antibody microarray as a well-developed technology is currently challenged by a few other established or emerging high-throughput technologies. In this ...

Immobilization of Multi-biocatalysts in Alginate Beads for Cofactor Regeneration and Improved Reusability

We have recently developed a simple, reusable and coupled whole-cell biocatalytic system with the capability of cofactor regeneration and biocatalyst immobilization for improved production yield and sustained synthesis. Described herewith is the experimental procedure for the development of such a system consisting of two E. coli strains that express functionally complementary enzymes. Together, these two enzymes can function co-operatively to mediate the regeneration of expensive cofactors for improving the product yield of the bioreaction. In addition, the method of synthesizing an immobilized form of the coupled biocatalytic system by encapsulation of whole cells in calcium alginate beads is reported. As an example, we present the improved biosynthesis of L-xylulose from L-arabinitol by coupling E. coli cells expressing the enzymes L-arabinitol dehydrogenase or NADH oxidase. Under optimal conditions and using an initial concentration of 150 mM L-arabinitol, the maximal L-xylulose yield reached 96%, which is higher than those reported in the literature. The immobilized form of the coupled whole-cell biocatalysts demonstrated good operational stability, maintaining 65% of the yield obtained in the first cycle after 7 cycles of successive re-use, while the free cell system almost completely lost the catalytic activity. Therefore, the methods reported here provides two strategies that could help improve the industrial production of L-xylulose, as well as other value-added compounds requiring the use of cofactors in general.

Presented is the protocol for co-immobilizing whole-cell biocatalysts for cofactor regeneration and improved reusability, using the production of L-xylulose as an example. The cofactor regeneration is achieved by coupling two Escherichia coli strains expressing functionally complementary enzymes; the whole-cell biocatalyst immobilization is achieved by cell encapsulation in calcium alginate beads.

Imobilização de Multi-biocatalisadores em alginato Beads para Cofator Regeneração e melhorada Reutilização

We have recently developed a simple, reusable and coupled whole-cell biocatalytic system with the capability of cofactor regeneration and biocatalyst ...

Influence of Hybrid Perovskite Fabrication Methods on Film Formation, Electronic Structure, and Solar Cell Performance

Hybrid organic/inorganic halide perovskites have lately been a topic of great interest in the field of solar cell applications, with the potential to achieve device efficiencies exceeding other thin film device technologies. Yet, large variations in device efficiency and basic physical properties are reported. This is due to unintentional variations during film processing, which have not been sufficiently investigated so far. We therefore conducted an extensive study of the morphology and electronic structure of a large number of CH3NH3PbI3 perovskite where we show how the preparation method as well as the mixing ratio of educts methylammonium iodide and lead(II) iodide impact properties like film formation, crystal structure, density of states, energy levels, and ultimately the solar cell performance.

We present an extensive study on the effects of different fabrication methods for organic/inorganic perovskite thin films by comparing crystal structures, density of states, energy levels, and ultimately the solar cell performance.

Influência do híbrido Métodos perovskita Fabricação na formação do filme, Estrutura Eletrônica e desempenho da célula solar

Hybrid organic/inorganic halide perovskites have lately been a topic of great interest in the field of solar cell applications, with the potential to ...

Fabrication and Testing of Photonic Thermometers

In recent years, a push for developing novel silicon photonic devices for telecommunications has generated a vast knowledge base that is now being leveraged for developing sophisticated photonic sensors. Silicon photonic sensors seek to exploit the strong confinement of light in nano-waveguides to transduce changes in physical state to changes in resonance frequency. In the case of thermometry, the thermo-optic coefficient, i.e., changes in refractive index due to temperature, causes the resonant frequency of the photonic device such as a Bragg grating to drift with temperature. We are developing a suite of photonic devices that leverage recent advances in telecom compatible light sources to fabricate cost-effective photonic temperature sensors, which can be deployed in a wide variety of settings ranging from controlled laboratory conditions, to the noisy environment of a factory floor or a residence. In this manuscript, we detail our protocol for the fabrication and testing of photonic thermometers.

We describe the process of fabrication and testing of photonic thermometers.

Fabricação e teste dos termómetros fotônicos

In recent years, a push for developing novel silicon photonic devices for telecommunications has generated a vast knowledge base that is now being ...

Fabrication and Testing of Catalytic Aerogels Prepared Via Rapid Supercritical Extraction

Protocols for preparing and testing catalytic aerogels by incorporating metal species into silica and alumina aerogel platforms are presented. Three preparation methods are described: (a) the incorporation of metal salts into silica or alumina wet gels using an impregnation method; (b) the incorporation of metal salts into alumina wet gels using a co-precursor method; and (c) the addition of metal nanoparticles directly into a silica aerogel precursor mixture. The methods utilize a hydraulic hot press, which allows for rapid (&#60;6 h) supercritical extraction and results in aerogels of low density (0.10 g/mL) and high surface area (200-800 m2/g). While the work presented here focuses on the use of copper salts and copper nanoparticles, the approach can be implemented using other metal salts and nanoparticles. A protocol for testing the three-way catalytic ability of these aerogels for automotive pollution mitigation is also presented. This technique uses custom-built equipment, the Union Catalytic Testbed (UCAT), in which a simulated exhaust mixture is passed over an aerogel sample at a controlled temperature and flow rate. The system is capable of measuring the ability of the catalytic aerogels, under both oxidizing and reducing conditions, to convert CO, NO and unburned hydrocarbons (HCs) to less harmful species (CO2, H2O and N2). Example catalytic results are presented for the aerogels described.

Here we present protocols for preparing and testing catalytic aerogels by incorporating metal species into silica and alumina aerogel platforms. Methods for preparing materials using copper salts and copper-containing nanoparticles are featured. Catalytic testing protocols demonstrate the effectiveness of these aerogels for three-way catalysis applications.

Fabricação e teste de catalítico Aerogels preparado através da rápida extração supercrítica

Protocols for preparing and testing catalytic aerogels by incorporating metal species into silica and alumina aerogel platforms are presented. Three ...

Preparation of Poly(pentafluorophenyl acrylate) Functionalized SiO2 Beads for Protein Purification

We demonstrate a simple method to prepare poly(pentafluorophenyl acrylate) (poly(PFPA)) grafted silica beads for antibody immobilization and subsequent immunoprecipitation (IP) application. The poly(PFPA) grafted surface is prepared via a simple two-step process. In the first step, 3-aminopropyltrimethoxysilane (APTMS) is deposited as a linker molecule onto the silica surface. In the second step, poly(PFPA) homopolymer, synthesized via the reversible addition and fragmentation chain transfer (RAFT) polymerization, is grafted to the linker molecule through the exchange reaction between the pentafluorophenyl (PFP) units on the polymer and the amine groups on APTMS. The deposition of APTMS and poly(PFPA) on the silica particles are confirmed by X-ray photoelectron spectroscopy (XPS), as well as monitored by the particle size change measured via dynamic light scattering (DLS). To improve the surface hydrophilicity of the beads, partial substitution of poly(PFPA) with amine-functionalized poly(ethylene glycol) (amino-PEG) is also performed. The PEG-substituted poly(PFPA) grafted silica beads are then immobilized with antibodies for IP application. For demonstration, an antibody against protein kinase RNA-activated (PKR) is employed, and IP efficiency is determined by Western blotting. The analysis results show that the antibody immobilized beads can indeed be used to enrich PKR while non-specific protein interactions are minimal.

Preparation of Polypentafluorophenyl acrylate Functionalized SiO2 Beads for Protein Purification

A protocol for the preparation of poly(pentafluorophenyl acrylate) (poly(PFPA)) grafted silica beads is presented. The poly(PFPA) functionalized surface is then immobilized with antibodies and used successfully for the protein separation through immunoprecipitation.

Preparação de Poly(pentafluorophenyl acrylate) acrescida SiO2 grânulos para purificação de proteínas

We demonstrate a simple method to prepare poly(pentafluorophenyl acrylate) (poly(PFPA)) grafted silica beads for antibody immobilization and subsequent ...

Fabrication of Thin Film Silver/Silver Chloride Electrodes with Finely Controlled Single Layer Silver Chloride

This paper aims to present a protocol to form smooth and well-controlled films of silver/silver chloride (Ag/AgCl) with designated coverage on top of thin film silver electrodes. Thin film silver electrodes sized 80 &#181;m x 80 &#181;m and 160 &#181;m x 160 &#181;m were sputtered on quartz wafers with a chromium/gold (Cr/Au) layer for adhesion. After passivation, polishing and cathodic cleaning processes, the electrodes underwent galvanostatic oxidation with consideration of Faraday&#39;s Law of Electrolysis to form smooth layers of AgCl with a designated degree of coverage on top of the silver electrode. This protocol is validated by inspection of scanning electron microscope (SEM) images of the surface of the fabricated Ag/AgCl thin film electrodes, which highlights the functionality and performance of the protocol. Sub-optimally fabricated electrodes are fabricated as well for comparison. This protocol can be widely used to fabricate Ag/AgCl electrodes with specific impedance requirements (e.g., probing electrodes for impedance sensing applications like impedance flow cytometry and interdigitated electrode arrays).

This paper aims to present a method to form smooth and well-controlled films of silver chloride (AgCl) with designated coverage on top of thin film silver electrodes.

Fabricação de eletrodos de cloreto de prata/prata de filme fino com cloreto de prata de camada única finamente controlado

This paper aims to present a protocol to form smooth and well-controlled films of silver/silver chloride (Ag/AgCl) with designated coverage on top of thin ...

Grânulos modificados com porfirina em citometria de fluxo

Porphyrin-Modified Beads for Use as Compensation Controls in Flow Cytometry

Flow cytometry can rapidly characterize and quantify diverse cell populations based on fluorescence measurements. The cells are first stained with one or more fluorescent reagents, each functionalized with a different fluorescent molecule (fluorophore) that binds to cells selectively based on their phenotypic characteristics, such as cell surface antigen expression. The intensity of fluorescence from each reagent bound to cells can be measured on the flow cytometer using channels that detect a specified range of wavelengths. When multiple fluorophores are used, the light from individual fluorophores often spills over into undesired detection channels, which requires a correction to the fluorescence intensity data in a process called compensation. 
Compensation control particles, typically polymer beads bound to a single fluorophore, are needed for each fluorophore used in a cell labeling experiment. Data from compensation particles from the flow cytometer are used to apply a correction to the fluorescence intensity measurements. This protocol describes the preparation and purification of polystyrene compensation beads covalently functionalized with the fluorescent reagent meso-tetra(4-carboxyphenyl) porphine (TCPP) and their application in flow cytometry compensation. In this work, amine-functionalized polystyrene beads were treated with TCPP and the amide coupling reagent EDC (N-(3-dimethylaminopropyl)-N&#8242;-ethylcarbodiimide hydrochloride) at pH 6 and at room temperature for 16 h with agitation. The TCPP beads were isolated by centrifugation and resuspended in a pH 7 buffer for storage. TCPP-related particulates were observed as a byproduct. The number of these particulates could be reduced using an optional filtration protocol. The resultant TCPP beads were successfully used on a flow cytometer for compensation in experiments with human sputum cells labeled with multiple fluorophores. The TCPP beads proved stable following storage in a refrigerator for 300 days.

Autor em destaque: grânulos modificados por porfirina para uso como controles de compensação em citometria de fluxo  

The protocol describes how porphyrin-based compensation beads for flow cytometry are prepared by the reaction of amine-functionalized polystyrene beads with the porphyrin TCPP and the amide coupling reagent EDC. A filtration procedure is used to reduce the particulate byproducts.

Pérolas Modificadas com Porfirina para Uso como Controle de Compensação em Citometria de Fluxo

Flow cytometry can rapidly characterize and quantify diverse cell populations based on fluorescence measurements. The cells are first stained with one or ...