This research was supported by the Natural Sciences and Engineering Research Council (NSERC) of Canada, the Canada Research Chairs Program, and Simon Fraser University. This work made use of 4D LABS shared facilities supported by the Canada Foundation for Innovation (CFI), British Columbia Knowledge Development Fund (BCKDF) and Simon Fraser University.

1. Síntesis de la Nayf 4 / Yb 3+ / Er 3+ conversión ascendente nanopartículas (UCNP) <ol><li> La instalación del equipo como sigue: <ol><li> Coloque una capa de 250 ml de calentamiento en una placa de agitación regular y enchufe el manto a la pareja térmica. </li><li> Coloque un matraz de fondo redondo de 250 ml equipado con una barra de agitación magnética en el manto de calentamiento con sujeción adecuada. </li><li> Conecte un adaptador de aire a la parte izquierda del cuello del matraz de fondo redondo y conecte este adaptador de aire a la línea de Schlenk con un tubo de plástico. </li><li> Adjuntar un adaptador de vidrio a la parte derecha del cuello del matraz de fondo redondo y fijar un adaptador de termómetro en el adaptador de vidrio. Inserte la sonda de temperatura en el matraz a través del adaptador de termómetro y enchufar esto en el termopar. </li><li> Adjuntar una cabeza de destilación al cuello medio del matraz de fondo redondo. Coloque un tapón en la parte superior de la cabeza de destilación. Conectar la cabeza a un condensador, seguido por un vacío distillatadaptador de iones y un matraz de fondo redondo de 50 ml. Conecte el adaptador de destilación al vacío a un pelele a través de tubos de plástico. </li></ol></li><li> Pesar 1,17 g (3,9 mmol) de acetato de itrio, 0,439 g de acetato de iterbio y 0,0727 g (0,1 mmol) de acetato de erbio y colocarlos en la reacción matraz de fondo redondo. </li><li> Añadir 30 ml de ácido oleico y 75 ml de octadeceno al matraz usando un cilindro graduado. </li><li> Enjuague el lado de la reacción matraz de fondo redondo utilizando 5 ml de metanol para asegurarse de que ningún ácido oleico y octadeceno se pega a los lados del matraz de reacción. </li><li> Conectar el matraz de reacción a un colector de doble línea Schlenk y gire la válvula correspondiente para mantener el matraz de reacción conectado a la línea de nitrógeno. </li><li> Encienda el termopar, ajustar la temperatura a 80 ° C, y se calienta gradualmente el sistema a esta temperatura. A 80 ° C y después de que se disuelvan todos los materiales de partida, retirar el manto de calefacción y de permitir que la reacciónenfriar a 30 ° C. </li><li> Cuando la temperatura alcanza los 30 ° C, sacar la cabeza de destilación, cambie el adaptador de aire de la parte izquierda del cuello al cuello medio y cerrar el cuello de izquierda con un tapón. Poco a poco introducir vacío al matraz de reacción girando la válvula en la línea de Schlenk desde la línea de nitrógeno a la línea de vacío. Todos los componentes de bajo punto de ebullición se sacó de la reacción en este punto. </li><li> Cuando la solución deje de burbujear, levante la temperatura a 115 ° C en una velocidad de 5 ° C / min. </li><li> Una vez que la temperatura alcanza los 115 ° C, mantener esta temperatura durante 15 minutos, luego retire la camisa de calentamiento y enfriamiento de la reacción a 50 ° C. Después, cambiar rápidamente la puesta en marcha de nuevo a la forma original de volver a colocar la cabeza de destilación al cuello medio y el adaptador de aire a la cabeza de izquierda. </li><li> Pesar 0,74 g (12,5 mmol) de NaOH y 0,50 g (20,0 mmol) de NH 4 F durante el proceso de enfriamiento, y disolverlosen 50 ml de metanol por sonicación. </li><li> Después de la sonicación, se vierte la solución en el matraz de fondo redondo de reacción y enjuagar las paredes del matraz con 5 ml de MeOH. </li><li> Deja la solución de agitar a 50 ° C durante 30 min. </li><li> Aumentar la temperatura a 75 ° C para destilar el metanol. </li><li> Durante la destilación, vaciar el matraz de recogida cuando sea necesario. Una vez finalizada la destilación, calentar la reacción a 300 ° C bajo protección de nitrógeno lo más rápido posible. </li><li> Una vez que la temperatura alcanza 300 ° C, mantener esta temperatura durante 1 hora. Si es necesario, cubra la configuración con papel de aluminio para ayudar a mantener la temperatura. A continuación, retire la fuente de calor y permitir que la reacción se enfríe a temperatura ambiente. </li><li> Una vez que se enfría a temperatura ambiente, se dividió la solución de manera uniforme en tres tubos de centrifugación (tubos de 50 ml, aproximadamente 35 ml de solución por cada tubo), y la parte superior por el tubo a los 50 ml escala utilizando etanol anhidro. Centrífuga todo tél tubos a 3.400 xg durante 15 min. Después de la centrifugación, los UCNPs se deben observar en el lado de los tubos como un precipitado blanco. </li><li> Descartar el sobrenadante y redispersar los pellets UCNPs en hexanos (7,5 ml de hexano por cada tubo), y luego rellenar el tubo con etanol para la escala de 50 ml. Tubos de centrífuga de nuevo a 3400 xg durante 15 min. </li><li> Una vez que la centrifugación es completa, descartar el sobrenadante y redispersar los UCNPs sólidos en 30 ml de CHCl 3 para su uso posterior. </li></ol> 2. nanoconjuntos Asamblea de dispersables en agua que contienen Orgánica Tinte Moléculas y Nanopartículas conversión ascendente <ol><li> Disolver 25 mg (0,0147 mmol) de poli (anhídrido maleico estireno-alt) (PSMA) en 3 ml de CHCl 3 en un vial de centelleo equipado con una barra de agitación magnética. Esta cantidad es una cantidad optimizada después de múltiples ensayos. </li><li> Añadir 250 l (47 mg / ml) de la conversión ascendente nanopartículas solución de cloroformo acciones al Scintivial lación. </li><li> Tapar el frasco y lo coloca en la placa de agitación magnética, y se agita la solución a temperatura ambiente durante 2 horas. </li><li> Pesar 160 mg (0,0773 mmol) de poliéter amina 2070, y se disuelven en 1 ml de CHCl3. A continuación, añadir esta solución a la vial de centelleo en una porción con una pipeta. La solución se volverá a amarillo pálido que indica la reacción de poliéter amina 2070 con los grupos anhídrido en la PSMA. </li><li> Continuar agitando la solución durante la noche a temperatura ambiente. </li><li> Medir la cantidad apropiada de moléculas de colorante orgánicas entonces dispensarla en el vial de centelleo en una porción, se agitó la solución resultante durante 1 hr. <ol><li> Para la muestra TPP-NP (que contiene nanoconjunto cubierta de polímero, tetrafenilporfirina y nanopartículas conversión ascendente), directamente añadir 1 mg de porfirina tetrafenil al vial de centelleo. Para la muestra DAE-UCNP (que contiene nanoconjunto cubierta de polímero, moléculas diarileteno y nanopartículas upconvertings), la cantidad de cada moléculas de diarileteno es 2 × 10 -7 mol. Añadir las dos moléculas de diarileteno en la solución de reacción. Los volúmenes de las dos moléculas diarileteno son: DAE-1o (1,8 mM), 111 l y DAE-2o (1,6 mM), 125 l. </li></ol></li><li> Se elimina el disolvente CHCl 3 bajo presión reducida usando un evaporador rotatorio, a continuación, añadir 3 ml de 0,001 acuosa de NaOH (pH ≈ 11) M al vial de centelleo, después sonicar el vial hasta que se forma una suspensión lechosa. </li><li> Coloque el vial de nuevo en el evaporador rotativo, y retirar con cuidado el resto CHCl3 hasta que la suspensión se ha convertido en una solución clara. </li><li> Transferir la solución del vial de centelleo para dos tubos de centrifugación cónicos de 1,5 ml y centrifugar la solución a 20.600 xg durante 25 min. </li><li> Descartar el sobrenadante, a continuación, añadir un total de 3 ml de H2O desionizada en los dos tubos (1,5 ml por tubo), sonicar los tubos para redispersar los pelletsen el H2O desionizada </li><li> Centrifugar los dos tubos de nuevo a 20.600 xg durante 25 min. </li><li> Descartar el sobrenadante, a continuación, añadir un total de 3 ml de H2O desionizada en los dos tubos (1,5 ml por tubo). Sonicar los tubos para redispersar los pellets en el desionizada H 2 O. </li><li> Filtrar la muestra acuosa nanopartículas dispersión a través de un filtro de jeringa de 0,2 micras para obtener la muestra final para la prueba adicional. </li></ol>

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The authors have nothing to disclose.

Las nanopartículas sintetizadas según este protocolo tienen una distribución de tamaño de 20 a 25 nm centrada en torno al 22,5 nm. 26,27 Se pueden clasificar como partículas esféricas con una estructura reticular 4 acogida α-Nayf. Hay dos pasos críticos en este protocolo. En la síntesis UCNP, es crucial para mantener la temperatura y el tiempo de calentamiento tan preciso como sea posible para asegurar una estrecha distribución de tamaño de partícula. La adición simultánea de NaOH y N...

Hoy en día todavía hay una necesidad urgente de desarrollar nuevos tipos de agentes bio-imágenes. Muchas sondas fluorescentes novedosos han sido bien documentados. 6.1 Sin embargo, las mejoras sustanciales en la resolución de la imagen sigue siendo un desafío. 7 Un método práctico es modular directamente las sondas de fluorescencia entre un estado de emisión &quot;luz&quot; y un estado apagada &#39;oscura&#39;. 8-12 Este método en particular se ha aplicado para desarrollar tecnologías, tales como el agotamiento de la emisión estimulada (STED) 13 microscopía y microscopía óptica de reconstrucción estocástico (Storm). 14 Otro enfoque para modular la fluorescencia es al par de cromóforos fotosensibles junto con sondas fluorescentes. 15,16 Alternar el cromóforo photoresponsive entre dos isómeros donde sólo uno de los isómeros puede actuar como un aceptor de transferencia de energía eficiente, permite el control sobre la extinción de la fluorescencia de The sonda a través de transferencia de energía de resonancia Förster (FRET) y otros mecanismos. El resultado es la creación de un Estado de emisión y un estado templado que puede ser alternado por la exposición del cromóforo photoresponsive a diferentes longitudes de onda de la luz. Cromóforos diarileteno fotosensibles se pueden activar de forma reversible entre un isómero de anillo abierto incolora y un isómero de anillo cerrado de color tras la irradiación con rayos UV y la luz visible. 17-19 La estabilidad térmica de los dos isómeros y espectros de absorción sintonizable del anillo cerrado maquillaje isómero diariletenos muy buenos candidatos como FRET controlable aceptantes. nanopartículas dopado con lantánidos 20-23 Nayf 4 conversión ascendente son útiles para la bio-imágenes. 24 Estas nanopartículas absorben la luz del infrarrojo cercano y emiten luz en varias regiones del espectro visible. Los ejemplos de modulación de la fluorescencia mediante la combinación de cromóforos diarileteno fotosensibles y nanopartículas han sido previamente reportados por nuestro grupo. 25-27 Sin embargo, los sistemas descritos en cada ejemplo requiere una modificación sintética adicional para fijar los diariletenos a la superficie de las nanopartículas, lo que complica el desarrollo de sistemas más diversos. Aquí se demuestra un método sencillo &quot;plug-and-play &#39;para preparar moléculas de colorante orgánico dispersables en agua y nanopartículas conversión ascendente fotosensibles utilizando una estrategia de auto-ensamblaje. La elección de los polímeros; poli (anhídrido maleico estireno-alt) y poliéter amina 2070 proporcionan tanto un entorno hidrófobo e hidrófilo. Las secciones hidrófobas del polímero ayuda para sostener las moléculas orgánicas normalmente insolubles en agua y nanopartículas conversión ascendente juntos, mientras que la región hidrófila del polímero es crítico para mantener la solubilidad en agua. Primero vamos a demostrar la síntesis de las nanopartículas de conversión ascendente por el método de la nucleación térmica. Entonces, vamos a probar how las moléculas orgánicas y nanopartículas conversión ascendente se encapsulan dentro de las regiones hidrófobas de la cubierta de polímero y permanecen estables en medios acuosos simplemente co-agitación una solución de la nanopartículas de conversión ascendente, polímero y diferentes moléculas de colorante orgánico, seguido por un procedimiento de tratamiento conveniente. También demostramos cómo modular la emisión de fluorescencia de los conjuntos utilizando la irradiación de luz externa. Anticipamos el alcance de la utilización de este método &quot;plug-and-play&quot; para hacer nanoconjuntos dispersables en agua continuarán expandiéndose.

<table border="0" cellpadding="0" cellspacing="0">
	<tbody>
		<tr>
			<td>yttrium acetate</td>
			<td>sigma</td>
			<td>326046</td>
			<td>Yttrium(III) acetate hydrate</td>
		</tr>
		<tr>
			<td>ytterbium acetate</td>
			<td>sigma</td>
			<td>544973</td>
			<td>&#160;Ytterbium(III) acetate hydrate&#160;</td>
		</tr>
		<tr>
			<td>erbium acetate</td>
			<td>sigma</td>
			<td>325570</td>
			<td>Erbium(III) acetate hydrate</td>
		</tr>
		<tr>
			<td>oleic acid</td>
			<td>sigma</td>
			<td>75096</td>
			<td>analytical standard</td>
		</tr>
		<tr>
			<td>octadecene</td>
			<td>sigma</td>
			<td>O806&#160;</td>
			<td>Technical grade&#160;</td>
		</tr>
		<tr>
			<td>NaOH</td>
			<td></td>
			<td>S5881&#160;</td>
			<td>reagent grade</td>
		</tr>
		<tr>
			<td>NH4F</td>
			<td></td>
			<td>216011</td>
			<td>ACS reagent</td>
		</tr>
		<tr>
			<td>poly(styrene-alt-maleic anhydride)</td>
			<td>sigma</td>
			<td>4422699</td>
			<td>Average Mn= 1700</td>
		</tr>
		<tr>
			<td>JeffAmine 2070</td>
			<td>Huntsman</td>
			<td>M-2070</td>
			<td></td>
		</tr>
		<tr>
			<td>Varian Carry 300</td>
			<td>Agilent</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>JDSU NIR laser</td>
			<td>JSDU</td>
			<td>L4-9897510-100M</td>
			<td>980 nm diode laser</td>
		</tr>
	</tbody>
</table>

a 'plug and play' method to create water-dispersible nanoassemblies containing an amphiphilic polymer, organic dyes and upconverting nanoparticles

In this protocol, we first describe a procedure to synthesize lanthanide doped upconverting nanoparticles (UCNPs). We then demonstrate how to generate amphiphilic polymers in situ, and describe a protocol to encapsulate the prepared UCNPs and different organic dye molecules (porphyrins and diarylethenes) using polymer shells to form stable water-dispersible nanoassemblies. The nanoassembly samples containing both the UCNPs and the diarylethene organic dyes have interesting photochemical and photophysical properties. Upon 365 nm UV irradiation, the diarylethene group undergoes a visual color change. When the samples are irradiated with visible light of another specific wavelength, the color fades and the samples return to the initial colorless state. The samples also emit visible light from the UCNPs upon irradiation with 980 nm near-infrared light. The emission intensity of the samples can be tuned through alternate irradiation with UV and visible light. Modulation of fluorescence can be performed for many cycles without observable degradation of the samples. This versatile encapsulation procedure allows for the transfer of hydrophobic molecules and nanoparticles from an organic solvent to an aqueous medium. The polymer helps to maintain a lipid-like microenvironment for the organic molecules to aid in preservation of their photochemical behavior in water. Thus this method is ideal to prepare water-dispersible photoresponsive systems. The use of near-infrared light to activate upconverting nanoparticles allows for lower energy light to be used to activate photoreactions instead of more harmful ultraviolet light.

Los espectros de absorción y espectros de fotoluminiscencia se recogieron para la muestra DAE-UCNP. Los espectros de absorción se utilizan para comparar la superposición espectral entre los cromóforos diarileteno cerradas y las nanopartículas conversión ascendente. Las fotografías de las muestras (tanto TPP-UCNP y DAE-UCNP) también se incluyen para demostrar la encapsulación con éxito de moléculas de colorante orgánicos y nanopartículas conversión ascendente, que se encuentran dentro de las conchas de pol?...

Watch this Scientific Journal Video about A 'Plug and Play' Method to Create Water-dispersible Nanoassemblies Containing an Amphiphilic Polymer, Organic Dyes and Upconverting Nanoparticles at JoVE.com

A &#039;Plug and Play&#039; Method to Create Water-dispersible Nanoassemblies Containing an Amphiphilic Polymer, Organic Dyes and Upconverting Nanoparticles

Organic dye molecules and oleic acid coated upconverting nanoparticles are not water-soluble. This protocol describes a &#8216;plug and play&#8217; method that enables the transfer of organic dye molecules and upconverting particles from their initial hydrophobic solvent to water.

Un método &#39;Plug and Play&#39; para crear nanoconjuntos dispersables en agua que contiene un polímero anfífilo, colorantes orgánicos y conversión ascendente Nanopartículas

In this protocol, we first describe a procedure to synthesize lanthanide doped upconverting nanoparticles (UCNPs). We then demonstrate how to generate ...

a-plug-play-method-to-create-water-dispersible-nanoassemblies

Research

JoVE Journal

Chemistry

A 'Plug and Play' Method to Create Water-dispersible Nanoassemblies Containing an Amphiphilic Polymer, Organic Dyes and Upconverting Nanoparticles

9.8K vistas.  Simon Fraser University. Organic dye molecules and oleic acid coated upconverting nanoparticles are not water-soluble. This protocol describes a ‘plug and play’ method that enables the transfer of organic dye molecules and upconverting particles from their initial hydrophobic solvent to water. 

Video: A 'Plug and Play' Method to Create Water-dispersible Nanoassemblies Containing an Amphiphilic Polymer, Organic Dyes and Upconverting Nanoparticles

Analysis of Volatile and Oxidation Sensitive Compounds Using a Cold Inlet System and Electron Impact Mass Spectrometry

This video presents a protocol for the mass spectrometrical analysis of volatile and oxidation sensitive compounds using electron impact ionization. The analysis of volatile and oxidation sensitive compounds by mass spectrometry is not easily achieved, as all state-of-the-art mass spectrometric methods require at least one sample preparation step, e.g., dissolution and dilution of the analyte (electrospray ionization), co-crystallization of the analyte with a matrix compound (matrix-assisted laser desorption/ionization), or transfer of the prepared samples into the ionization source of the mass spectrometer, to be conducted under atmospheric conditions. Here, the use of a sample inlet system is described which enables the analysis of volatile metal organyls, silanes, and phosphanes using a sector field mass spectrometer equipped with an electron impact ionization source. All sample preparation steps and the sample introduction into the ion source of the mass spectrometer take place either under air-free conditions or under vacuum, enabling the analysis of compounds highly susceptible to oxidation. The presented technique is especially of interest for inorganic chemists, working with metal organyls, silanes, or phosphanes, which have to be handled using inert conditions, such as the Schlenk technique. The principle of operation is presented in this video.

This video presents a protocol for the mass spectrometrical analysis of volatile and oxidation sensitive compounds using electron impact ionization. The presented technique is especially of interest for inorganic chemists, working with metal organyls, silanes, or phosphanes which have to be handled using inert conditions, such as the Schlenk technique.

Análisis de compuestos volátiles y sensibles oxidación usando un sistema de entrada de frío y de Impacto electrónico Espectrometría de Masas

This video presents a protocol for the mass spectrometrical analysis of volatile and oxidation sensitive compounds using electron impact ionization. The ...

Investigación

Química

Synthesis and Characterization of Functionalized Metal-organic Frameworks

Metal-organic frameworks have attracted extraordinary amounts of research attention, as they are attractive candidates for numerous industrial and technological applications. Their signature property is their ultrahigh porosity, which however imparts a series of challenges when it comes to both constructing them and working with them. Securing desired MOF chemical and physical functionality by linker/node assembly into a highly porous framework of choice can pose difficulties, as less porous and more thermodynamically stable congeners (e.g., other crystalline polymorphs, catenated analogues) are often preferentially obtained by conventional synthesis methods. Once the desired product is obtained, its characterization often requires specialized techniques that address complications potentially arising from, for example, guest-molecule loss or preferential orientation of microcrystallites. Finally, accessing the large voids inside the MOFs for use in applications that involve gases can be problematic, as frameworks may be subject to collapse during removal of solvent molecules (remnants of solvothermal synthesis). In this paper, we describe synthesis and characterization methods routinely utilized in our lab either to solve or circumvent these issues. The methods include solvent-assisted linker exchange, powder X-ray diffraction in capillaries, and materials activation (cavity evacuation) by supercritical CO2 drying. Finally, we provide a protocol for determining a suitable pressure region for applying the Brunauer-Emmett-Teller analysis to nitrogen isotherms, so as to estimate surface area of MOFs with good accuracy.

Synthesis, activation, and characterization of intentionally designed metal-organic framework materials is challenging, especially when building blocks are incompatible or unwanted polymorphs are thermodynamically favored over desired forms. We describe how applications of solvent-assisted linker exchange, powder X-ray diffraction in capillaries and activation via supercritical CO2 drying, can address some of these challenges.

Marcos de síntesis y caracterización de funcionalizado metal-orgánico

Metal-organic frameworks have attracted extraordinary amounts of research attention, as they are attractive candidates for numerous industrial and ...

A Simple Method for the Size Controlled Synthesis of Stable Oligomeric Clusters of Gold Nanoparticles under Ambient Conditions

Reducing dilute aqueous HAuCl4 with sodium thiocyanate (NaSCN) under alkaline conditions produces 2 to 3 nm diameter nanoparticles. Stable grape-like oligomeric clusters of these yellow nanoparticles of narrow size distribution are synthesized under ambient conditions via two methods. The delay-time method controls the number of subunits in the oligoclusters by varying the time between the addition of HAuCl4 to alkaline solution and the subsequent addition of reducing agent, NaSCN. The yellow oligoclusters produced range in size from ~3 to ~25 nm. This size range can be further extended by an add-on method utilizing hydroxylated gold chloride (Na+[Au(OH4-x)Clx]-) to auto-catalytically increase the number of subunits in the as-synthesized oligocluster nanoparticles, providing a total range of 3 nm to 70 nm. The crude oligocluster preparations display narrow size distributions and do not require further fractionation for most purposes. The oligoclusters formed can be concentrated &#62;300 fold without aggregation and the crude reaction mixtures remain stable for weeks without further processing. Because these oligomeric clusters can be concentrated before derivatization they allow expensive derivatizing agents to be used economically. In addition, we present two models by which predictions of particle size can be made with great accuracy.

We describe a simple method for producing highly stable oligomeric clusters of gold nanoparticles via the reduction of chloroauric acid (HAuCl4) with sodium thiocyanate (NaSCN). The oligoclusters have a narrow size distribution and can be produced with a wide range of sizes and surface coats.

Un método simple para la síntesis controlada de tamaño estables Clusters oligómeros de nanopartículas de oro bajo condiciones ambientales

Reducing dilute aqueous HAuCl4 with sodium thiocyanate (NaSCN) under alkaline conditions produces 2 to 3 nm diameter nanoparticles. Stable grape-like ...

An ELISA Based Binding and Competition Method to Rapidly Determine Ligand-receptor Interactions

A comprehensive understanding of signaling pathways requires detailed knowledge regarding ligand-receptor interaction. This article describes two fast and reliable point-by-point protocols of enzyme-linked immunosorbent assays (ELISAs) for the investigation of ligand-receptor interactions: the direct ligand-receptor interaction assay (LRA) and the competition LRA. As a case study, the ELISA based analysis of the interaction between different lambda interferons (IFNLs) and the alpha subunit of their receptor (IL28RA) is presented: the direct LRA is used for the determination of dissociation constants (KD values) between receptor and IFN ligands, and the competition LRA for the determination of the inhibitory capacity of an oligopeptide, which was designed to compete with the IFNLs at their receptor binding site. Analytical steps to estimate KD and half maximal inhibitory concentration (IC50) values are described. Finally, the discussion highlights advantages and disadvantages of the presented method and how the results enable a better molecular understanding of ligand-receptor interactions.

The presented protocols describe two enzyme-linked immunosorbent assay (ELISA) based techniques for the rapid investigation of ligand-receptor interactions: The first assay allows the determination of dissociation constant between ligand and receptor. The second assay enables a rapid screening of blocking peptides for ligand-receptor interactions.

Un ELISA basado Encuadernación y método Competencia determinación rápida interacciones ligando-receptor

A comprehensive understanding of signaling pathways requires detailed knowledge regarding ligand-receptor interaction. This article describes two fast and ...

The Preparation and Properties of Thermo-reversibly Cross-linked Rubber Via Diels-Alder Chemistry

A method for using Diels Alder thermo-reversible chemistry as cross-linking tool for rubber products is demonstrated. In this work, a commercial ethylene-propylene rubber, grafted with maleic anhydride, is thermo-reversibly cross-linked in two steps. The pending anhydride moieties are first modified with furfurylamine to graft furan groups to the rubber backbone. These pendant furan groups are then cross-linked with a bis-maleimide via a Diels-Alder coupling reaction. Both reactions can be performed under a broad range of experimental conditions and can easily be applied on a large scale. The material properties of the resulting Diels-Alder cross-linked rubbers are similar to a peroxide-cured ethylene/propylene/diene rubber (EPDM) reference. The cross-links break at elevated temperatures (&#62; 150 &#176;C) via the retro-Diels-Alder reaction and can be reformed by thermal annealing at lower temperatures (50-70 &#176;C). Reversibility of the system was proven with infrared spectroscopy, solubility tests and mechanical properties. Recyclability of the material was also shown in a practical way, i.e., by cutting a cross-linked sample into small parts and compression molding them into new samples displaying comparable mechanical properties, which is not possible for conventionally cross-linked rubbers.

A simple two-step approach involving rubber modification and cross-linking yields fully reworkable, elastic rubber products.

La preparación y propiedades de termo-reversible reticulado Química Caucho Vía de Diels-Alder

A method for using Diels Alder thermo-reversible chemistry as cross-linking tool for rubber products is demonstrated. In this work, a commercial ...

An Optimized Protocol for the Efficient Radiolabeling of Gold Nanoparticles by Using a 125I-labeled Azide Prosthetic Group

Here, we demonstrate a detailed protocol for the radiosynthesis of a 125I-labeled azide prosthetic group and its application to the efficient radiolabeling of DBCO-group-functionalized gold nanoparticles using a copper-free click reaction. Radioiodination of the stannylated precursor (2) was carried out by using [125I]NaI and chloramine T as an oxidant at room temperature for 15 min. After HPLC purification of the crude product, the purified 125I-labeled azide (1) was obtained with high radiochemical yield (75 &plusmn; 10%, n = 8) and excellent radiochemical purity (&gt;99%). For the synthesis of radiolabeled 13-nm-sized gold nanoparticles, the DBCO-functionalized gold nanoparticles (3) were prepared by using a thiolated polyethylene glycol polymer. A copper-free click reaction between 1 and 3 gave the 125I-labeled gold nanoparticles (4) with more than 95% of radiochemical yield as determined by radio-thin-layer chromatography (radio-TLC). These results clearly indicate that the present radiolabeling method using a strain-promoted copper-free click reaction will be useful for the efficient and convenient radiolabeling of DBCO-group-containing nanomaterials.

An Optimized Protocol for the Efficient Radiolabeling of Gold Nanoparticles by Using a 125I-labeled Azide Prosthetic Group

A detailed procedure for the synthesis of a 125I-labeled azide and the radiolabeling of dibenzocyclooctyne (DBCO)-group-conjugated, 13-nm-sized gold nanoparticles using a copper-free click reaction is described.

Un protocolo optimizado para el radiomarcaje eficaz de nanopartículas de oro mediante el uso de una<sup&gt; 125</sup&gt; Azida grupo prostético marcado con I

Here, we demonstrate a detailed protocol for the radiosynthesis of a 125I-labeled azide prosthetic group and its application to the efficient ...

Grafting Multiwalled Carbon Nanotubes with Polystyrene to Enable Self-Assembly and Anisotropic Patchiness

We demonstrate a straightforward protocol to graft pristine multiwalled carbon nanotubes (MWCNTs) with polystyrene (PS) chains at the sidewalls through a free-radical polymerization strategy to enable the modulation of the nanotube surface properties and produce supramolecular self-assembly of the nanostructures. First, a selective hydroxylation of the pristine nanotubes through a biphasic catalytically mediated oxidation reaction creates superficially distributed reactive sites at the sidewalls. The latter reactive sites are subsequently modified with methacrylic moieties using a silylated methacrylic precursor to create polymerizable sites. Those polymerizable groups can address further polymerization of styrene to produce a hybrid nanomaterial containing PS chains grafted to the nanotube sidewalls. The polymer-graft content, amount of silylated methacrylic moieties introduced and hydroxylation modification of the nanotubes are identified and quantified by Thermogravimetric Analysis (TGA). The presence of reactive functional groups hydroxyl and silylated methacrylate are confirmed by Fourier Transform Infrared Spectroscopy (FT-IR). Polystyrene-grafted carbon nanotube solutions in tetrahydrofuran (THF) provide wall-to-wall collinearly self-assembled nanotubes when cast samples are analyzed by transmission electron microscopy (TEM). Those self-assemblies are not obtained when suitable blanks are similarly cast from analogous solutions containing non-grafted counterparts. Therefore, this method enables the modification of the nanotube anisotropic patchiness at the sidewalls which results into spontaneous auto-organization at the nanoscale.

A procedure for the synthesis of polystyrene-grafted multiwalled carbon nanotubes using successive chemical modification steps to selectively introduce the polymer chains to the sidewalls and their self-assembly via anisotropic patchiness is presented.

Injerto de nanotubos de carbono pirólisis con poliestireno para permitir uno mismo-Asamblea y pliegues anisotrópico

We demonstrate a straightforward protocol to graft pristine multiwalled carbon nanotubes (MWCNTs) with polystyrene (PS) chains at the sidewalls through a ...

Time-resolved Photophysical Characterization of Triplet-harvesting Organic Compounds at an Oxygen-free Environment Using an iCCD Camera

Here, we present a sensible method of the acquisition and analysis of time-resolved photoluminescence using an ultrafast iCCD camera. This system enables the acquisition of photoluminescence spectra covering the time regime from nanoseconds up to 0.1 s. This enables us to follow the changes in the intensity (decay) and emission of the spectra over time. Using this method, it is possible to study diverse photophysical phenomena, such as the emission of phosphorescence, and the contributions of prompt and delayed fluorescence in molecules showing thermally activated delayed fluorescence (TADF). Remarkably, all spectra and decays are obtained in a single experiment. This can be done for solids (thin film, powder, crystal) and liquid samples, where the only limitations are the spectral sensitivity of the camera and the excitation wavelength (532 nm, 355 nm, 337 nm, and 266 nm). This technique is, thus, very important when investigating the excited state dynamics in organic emitters for their application in organic light-emitting diodes and other areas where triplet harvesting is of paramount importance. Since triplet states are strongly quenched by oxygen, emitters with efficient TADF luminescence, or those showing room temperature phosphorescence (RTP), must be correctly prepared in order to remove any dissolved oxygen from solutions and films. Otherwise, no long-lived emission will be observed. The method of degassing solid samples as presented in this work is basic and simple, but the degassing of liquid samples creates additional difficulties and is particularly interesting. A method of minimizing solvent loss and changing the sample concentration, while still enabling to remove oxygen in a very efficient and a repeatable manner, is presented in this work.

Here, we present a method of the spectroscopic characterization of organic molecules by means of time-resolved photoluminescence spectroscopy on the nanosecond-to-millisecond timescale in oxygen-free conditions. Methods to efficiently remove oxygen from the samples and, thus, limit luminescence quenching are also described.

Tiempo-resolved fotofísicas caracterización de trío cosecha compuestos orgánicos en un libre de oxígeno ambiente usando un iCCD cámara

Here, we present a sensible method of the acquisition and analysis of time-resolved photoluminescence using an ultrafast iCCD camera. This system enables ...

Raman and IR Spectroelectrochemical Methods as Tools to Analyze Conjugated Organic Compounds

In the presented work, two spectroelectrochemical techniques are discussed as tools for the analysis of the structural changes occurring in the molecule on the vibrational level of energy. Raman and IR spectroelectrochemistry can be used for advanced characterization of the structural changes in the organic electroactive compounds. Here, the step-by-step analysis by means of Raman and IR spectroelectrochemistry is shown. Raman and IR spectroelectrochemical techniques provide complementary information about structural changes occurring during an electrochemical process, i.e. allows for the investigation of redox processes and their products. The examples of IR and Raman spectroelectrochemical analysis are presented, in which the products of the redox reactions, both in solution and solid state, are identified.

A protocol of step-by-step Raman and IR spectroelectrochemical analysis is presented.

Raman y métodos IR electroquímicas como herramientas para analizar compuestos orgánicos conjugados

In the presented work, two spectroelectrochemical techniques are discussed as tools for the analysis of the structural changes occurring in the molecule ...

Controlled Photoredox Ring-Opening Polymerization of O-Carboxyanhydrides Mediated by Ni/Zn Complexes

Here, we describe an effective protocol that combines photoredox Ni/Ir catalysis with the use of a Zn-alkoxide for efficient ring-opening polymerization, allowing for the synthesis of isotactic poly(&#945;-hydroxy acids) with expected molecular weights (&#62;140 kDa) and narrow molecular weight distributions (Mw/Mn &#60; 1.1). This ring-opening polymerization is mediated by Ni and Zn complexes in the presence of an alcohol initiator and a photoredox Ir catalyst, irradiated by a blue LED (400 - 500 nm). The polymerization is performed at a low temperature (-15 &#176;C) to avoid undesired side reactions. The complete monomer consumption can be achieved within 4 - 8 hours, providing a polymer close to the expected molecular weight with narrow molecular weight distribution. The resulted number-average molecular weight shows a linear correlation with the degree of polymerization up to 1000. The homodecoupling 1H NMR study confirms that the obtained polymer is isotactic without epimerization. This polymerization reported herein offers a strategy for achieving rapid, controlled O-carboxyanhydrides polymerization to prepare stereoregular poly(&#945;-hydroxy acids) and its copolymers bearing various functional side-chain groups.

Controlled Photoredox Ring-Opening Polymerization of O-Carboxyanhydrides Mediated by Ni/Zn Complexes

A protocol for the controlled photoredox ring-opening polymerization of O-carboxyanhydrides mediated by Ni/Zn complexes is presented.

Controla la polimerización de apertura de Photoredox de O- Carboxyanhydrides mediada por complejos de Ni/Zn

Here, we describe an effective protocol that combines photoredox Ni/Ir catalysis with the use of a Zn-alkoxide for efficient ring-opening polymerization, ...