DCH, MB y FK fueron apoyados por un seguimiento EPSRC el Fondo. BL-V y DS fueron cada apoyados por becas de doctorado MRC. KC fue apoyado por la financiación de la Plataforma de Medicina Regenerativa del Reino Unido.

1 Síntesis de PHNGAD (Poli [1,6-hexanodiol / neopentil glicol / di (etilenglicol)-ácido adípico -alt] diol) <img alt="Esquema 1" fo:content-width="5in" src="/files/ftp_upload/51723/51723scheme1.jpg" width="500" /> Esquema 1: Síntesis de PHNAGD Representación esquemática de la síntesis de PHNAGD.. PHNAGD se preparó por la reacción de 1,6-Hexanodiol, dietilenglicol, neoppentyl y ácido adípico. PHNAGD, Poly [1,6-hexanodiol / neopentil glicol / di (etilenglicol)-ácido adípico -alt] diol. <ol><li> Aplicar un tratamiento térmico a los monómeros de 1,6-hexanodiol, di (etilenglicol) y neopentilglicol a 40 ° C durante 48 horas en un horno de vacío para eliminar el agua residual. Permitir al frío a temperatura ambiente bajo vacío. </li><li> Añadir 22 mmol de cada monómero y ácido adípico (55 mmol) a un matraz de fondo redondo de dos bocas, equipado con una barra de agitación y conectado a un aparato de Dean-Stark. </li><li> Coloque todo el conjunto bajo un vacío y calentar suavemente el glassware a 40 ° C durante 6 horas, con el fin de evitar cualquier absorción de humedad durante la adición de la sustancia química en el matraz. </li><li> Añadir medio de una jeringa, gota a gota, 0,0055 mol del catalizador de titanio (IV) butóxido de potasio. </li><li> Se agita la mezcla de reacción a 180 ° C, bajo una atmósfera de N2 durante 24 horas, y recoger el agua residual en la trampa Dean-Stark. Deje que el producto se enfríe a temperatura ambiente. </li></ol> 2 Síntesis de PU134 <img alt="Esquema 2" fo:content-width="5in" src="/files/ftp_upload/51723/51723scheme2.jpg" width="500" /> Esquema 2: Síntesis de PU134 Representación esquemática de la síntesis de poliuretano 134. PU134 se preparó por la reacción de 1,0 equivalentes de un PHNGAD con 2,0 equiv de un 4,4 &#39;-metilenbis (isocianato de fenilo), seguido por la adición de 1,0. equiv de un extensor de cadena de 1,4-butanodiol. <ol><li> Mezclar un equivalente de la PHNGAD poliol (Mn ~ 1800 Da, 3,2 mmol) con dos equivalentes de 4&#39;4-metilenbis (isocianato de fenilo) (6,4 mmol) en N, N-dimetilformamida (12 ml). </li><li> Se agita la mezcla de reacción a 70 ° C, bajo una atmósfera de N2. </li><li> Añadir medio de una jeringa, gota a gota el catalizador de titanio (IV) butóxido de potasio (0,8% en peso). </li><li> Después de 1 hora, añadir un equivalente del prolongador de cadena de 1,4-butanodiol (3,2 mmol). Aumentar la temperatura a 90 ° C y se agita durante 24 h bajo una atmósfera de N2. </li><li> Después de la reacción, recoger el poliuretano por precipitación por adición de éter dietílico (hexano o el agua también podría ser utilizado) gota a gota a la solución de reacción hasta que se produce la precipitación. </li><li> Centrifugar la solución a 5.300 xg durante 5 min. </li><li> Decantar el sobrenadante y secar a 40 ° C en un horno de vacío hasta que el disolvente se evapora. Nota: Con el fin de garantizar que el producto final de la reacción poseen los parámetros correctos con respecto a la distribución de peso molecular, los principales grupos funcionalesps del polímero, y las temperaturas de fusión y de transición vítrea, diversas técnicas y métodos de análisis se puede utilizar, tal como cromatografía de permeación en gel o espectroscopia FITR. </li></ol> 3 Preparación de Soluciones PU134 <ol><li> Pesar 200 mg de PU134 en una botella de vidrio. </li><li> Diluir PU134 a una concentración final de 2% en una serie de disolventes: cloroformo, una combinación de cloroformo y tolueno en proporción 1: 1, tetrahidrofurano, y la combinación de tetrahidrofurano y diclorometano en proporción 1: 1. Nota: La elección del disolvente adecuado varía dependiendo del polímero de usar. Diferentes disolventes poseen diferentes puntos de ebullición que pueden afectar a la solubilización del polímero. </li><li> Agitar la solución vigorosamente durante 20 min a temperatura ambiente usando un agitador a una velocidad de 200 mot / min, hasta que la solución se vuelve homogénea y se observó ningún precipitado. </li></ol> 4. revestimiento de cristal diapositivas con PU134 <ol><li> Coloque un round 15 mm 2 cubreobjetos en la recubridora de rotación. </li><li> Aplique 50 l de la solución PU134 a cada uno usando una pipeta. Ajustar el volumen de la solución PU134 en consecuencia para el tamaño requerido cubreobjetos manteniendo el volumen a la superficie relación proporcional. </li><li> Haga girar cada cubreobjetos de 7 segundos a 23 x g. </li><li> Aire cubreobjetos seco a temperatura ambiente durante al menos 24 horas antes de la esterilización. </li></ol> 5. irradiación de Cubreobjetos <ol><li> Gamma-irradiar cubreobjetos recubiertos de polímero mediante la aplicación de una dosis de 10 Grays usando un irradiador de laboratorio durante 12 min. </li><li> UV irradiar polímero recubierto cubreobjetos usando una 30 W, lámpara de rayos UV durante 16 minutos cada lado. </li><li> Coloque el cubreobjetos recubierto de polímero en una placa de cultivo tisular adecuado de acuerdo con el tamaño de diapositiva. </li></ol> 6. Microscopía Electrónica de Barrido <ol><li> Oro escudo cubreobjetos polímero mediante pulverización catódica de 200 seg en una atmósfera de 5 x 10 -1 milibares de presión. </li><li> Capturar la micrographs del cubreobjetos recubierto con polímero utilizando un microscopio electrónico de barrido a un voltaje de aceleración de 20 kV en modo de imagen de electrones secundarios. </li></ol> 7. Observaciones Microscopía de Fuerza Atómica <ol><li> Analiza un área de 20 x 20 m de la superficie del polímero. </li><li> Establecer una velocidad de barrido de 1,32 Hz a 1,60 Hz. </li><li> Configurar una resolución de 512 x 512 píxeles en la región explorada. </li><li> Calcula la raíz cuadrada media (RMS o Rq) del recubrimiento mediante el uso de la media de desviaciones de altitud tomadas del plano medio de datos de imagen, expresado como: <img fo:content-width="1in" src="/files/ftp_upload/51723/51723eq1.jpg" width="123" /> Cuando Zi es el valor actual Z, y N es el número de puntos dentro del área determinada. </li><li> 7.5 Se calcula la desviación o la media de rugosidad superficial (Ra) de la imagen utilizando, <img fo:content-width="1.5in" src="/files/ftp_upload/51723/51723eq2.jpg" width="154" /> Cuando Z (x) es la función que describe tque la superficie del perfil se analiza en términos de altura (Z) y la posición (x) de la muestra sobre la longitud de evaluación &quot;L&quot;. Ra representa el valor medio de la superficie con respecto al plano central. </li></ol> 8. Cultivo Celular y Diferenciación <ol><li> Cultura y diferenciar lo humano línea de células madre embrionarias (células madre) H9 como se describe en Hay 17. </li><li> Separar las células usando un reactivo de disociación y replate ellos en PU134 portaobjetos recubiertos en el Día 9 del proceso de diferenciación, en presencia de un medio libre de suero como se describe en Szkolnicka 18,19. Nota: Se prefiere el uso de una disociación celular enzimática para el desprendimiento de células físico. </li></ol> 9. citocromo P450 ensayo funcional <ol><li> Medir la actividad de CYP3A, siguiendo las instrucciones del fabricante. </li><li> Incubar hepatocitos derivados de células madre en el Día 13 o día 19, y medios sin células - como control negativo, con el substr apropiadacomió durante 5 horas a 37 ° C. </li><li> Recoger los sobrenadantes de las células y los medios de comunicación, llevar a cabo el ensayo según las instrucciones del fabricante. </li><li> Medir el nivel de actividad de CYP y relativa normalizada para el área de superficie (cm 2). </li></ol> 10. Inmunoticción <ol><li> Lave hESC deriva hepatocitos con PBS, durante 1 min, repita dos veces. </li><li> Añadir hielo frío metanol al 100% para fijar las células, en lugar de -20 ° C durante 10 min. </li><li> Lavar las células con PBS durante 5 min y repetir dos veces. </li><li> Se incuban las células con PBS / T (0,1% de Tween) / 10% de BSA durante 1 hora a RT. </li><li> Aspirar la solución PBST y añadir el anticuerpo primario apropiado diluido en PBS / T (0,1% de Tween) / 1% de BSA, se incuba a 4 ° C con suave agitación O / N. </li><li> Lavar las células con PBS / T (0,1% de Tween) / BSA al 1% durante 5 min y repetir tres veces. </li><li> Diluir el anticuerpo apropiado en PBS / T (0,1% de Tween) / 1% de BSA, añadir a las células y se incuba en la oscuridad a RT durante 1 h con agitación suave. </li><li> Lavar las células con PBS durante 5 min y repetir tres veces. </li><li> Añadir MOWIOL 488 (que contiene DAPI 1: 1.000) a cada pocillo, añadir un cubreobjetos con cuidado para reducir el número de burbujas de aire. Tienda células fija a 4 ° C en la oscuridad. Observe tinción utilizando un microscopio con un filtro adecuado y la lámpara fluorescente. Los anticuerpos primarios y secundarios optimizados se enumeran en la Tabla 1. </li></ol>

<ol>
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O. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=UV+and+gamma+irradiation+effects+on+surface+properties+of+polyurethane+derivate+from+castor+oil.">UV and gamma irradiation effects on surface properties of polyurethane derivate from castor oil.</a> Pol&#237;meros. 23 (3), 305-311 (2013).</li><li>Rosu, L., Cascaval, C. N., Ciobanu, C., Rosu, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effect+of+UV+radiation+on+the+semi-interpenetrating+polymer+networks+based+on+polyurethane+and+epoxy+maleate+of+bisphenol+A.">Effect of UV radiation on the semi-interpenetrating polymer networks based on polyurethane and epoxy maleate of bisphenol A.</a> Journal of Photochemistry and Photobilogy A: Chemistry. 169 (2), 177-185 (2005).</li><li>Yang, X. F., Tallman, D. E., Bierwagen, G. P., Croll, S. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Blistering+and+degradation+of+polyurethane+coatings+under+different+accelerated+weathering+tests.">Blistering and degradation of polyurethane coatings under different accelerated weathering tests.</a> Polymer Degradation and Stability. 77 (1), 103-109 (2002).</li></ol>

DCH es CSO, Director, fundador y accionista de FibromEd Products Ltd. MB y JPI son accionistas fundadores en FibromEd Products Ltd.

Muchos de los métodos actuales utilizados para generar hepatocitos a partir de células madre se basan en matrices indefinidos de origen animal. Estos sustratos pueden ser costosos y altamente variable, que afecta a la función celular y la estabilidad, lo que representa una barrera significativa a la aplicación. Por lo tanto, se realizó una pantalla para materiales sintéticos que apoyan la cultura de células madre de hepatocitos derivados. Hemos identificado, un poliuretano sencilla (PU134), formado por la polimer...

Los materiales biológicos han sido ampliamente utilizados en el mantenimiento y diferenciación de células madre pluripotentes 1. Al tiempo que permite, estos sustratos biológicos a menudo contienen una gran cantidad de componentes no definidos. Matrigel es un sustrato comúnmente utilizado para el cultivo de células madre y la diferenciación. Desafortunadamente, su composición variable influye en la función celular y el fenotipo. Aunque una variedad de matrices biológicas alternativas, más definidos se han utilizado 2-7, su origen animal o pobre escalabilidad les hace candidatos inadecuados para la fabricación industrial. Por lo tanto, la identificación de alternativas sintéticas, con composición definida y un rendimiento fiable, son objetivos clave en la investigación de células madre. En un intento de superar las limitaciones de los sustratos de cultivo de células definidos, colaboraciones interdisciplinarios entre la química y la biología han identificado materiales sintéticos con la capacidad de soportar el fenotipo celular. Synthsustratos etic son escalables, rentables, y se pueden fabricar en complejas estructuras 3D, imitando el entorno en vivo. Debido a estas propiedades sustratos sintéticos han sido ampliamente utilizados para apoyar y conducir la diferenciación de muchos tipos de células 8-10. Ensayos avanzados y de alto rendimiento han facilitado la rápida detección de los materiales sintéticos, de grandes bibliotecas, y entregado nuevos materiales con propiedades flexibles con amplias aplicaciones en la investigación y el desarrollo 11-13 biomédica. La utilización de un alto rendimiento, tecnología de tramado polímero micro-array, identificamos rápidamente en un sencillo de poliuretano (PU134), adecuado para el mantenimiento de los hepatocitos derivados de células madre humanas. Este polímero se encontró que era superior a sustratos derivados de animales con respecto a la diferenciación y la función de los hepatocitos 14-16. Hemos optimizado posteriormente el proceso de condiciones de recubrimiento, la topografía y la esterilización para acceder a efectosen el rendimiento del polímero en la estabilización de función de los hepatocitos y la vida útil. Esto tiene implicaciones significativas en cuanto a la comprensión de los fundamentos de la biología de los hepatocitos para el modelado basado en células y aplicaciones de medicina regenerativa. La tecnología aquí descrita representa un ejemplo de cómo la superficie de un polímero sintético puede ser optimizado para preservar el fenotipo celular. Creemos que la combinación de esta tecnología con un protocolo de diferenciación de hepatocitos sin suero eficiente tiene el potencial de proporcionar una producción escalable de hepatocitos para su uso en modelado in vitro y la medicina regenerativa.

<table border="0" cellpadding="0" cellspacing="0">
	<tbody>
		<tr>
			<td></td>
			<td></td>
			<td></td>
			<td>Synthesis, preparation, coating and characterization of polymer PU134 coated coverslips</td>
		</tr>
		<tr>
			<td>Shaker</td>
			<td>Edmun B&#252;hler</td>
			<td>KS-15</td>
			<td></td>
		</tr>
		<tr>
			<td>Irradiator</td>
			<td>CIS Biointernational</td>
			<td>IBL 637&#160;</td>
			<td></td>
		</tr>
		<tr>
			<td>Spin coater</td>
			<td>Specialty Coating System</td>
			<td>&#160;P-6708</td>
			<td></td>
		</tr>
		<tr>
			<td>Scanning Electron Microscope&#160;</td>
			<td>Philips</td>
			<td>XL30CPSEM</td>
			<td></td>
		</tr>
		<tr>
			<td>Atomic Force Microscope</td>
			<td>DimensionV Nanoscope, VEECO</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>p4-GLO CYP3A4</td>
			<td>Promega</td>
			<td>V8902</td>
			<td></td>
		</tr>
		<tr>
			<td>UV bulb</td>
			<td>ESCO</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>NanoScope analysis software</td>
			<td>VEECO</td>
			<td></td>
			<td>version 1.20</td>
		</tr>
		<tr>
			<td>Fluorescence microscope</td>
			<td>Olympus</td>
			<td>TH45200</td>
			<td>Use Volocity 4 Software</td>
		</tr>
		<tr>
			<td>Tissue culture plates</td>
			<td>Corning, UK&#160;</td>
			<td>3527</td>
			<td></td>
		</tr>
		<tr>
			<td>glass slides</td>
			<td>Scientific Laboratory Supplies</td>
			<td>MIC3308</td>
			<td></td>
		</tr>
		<tr>
			<td>Diethylene glycol</td>
			<td>Sigma&#8211;Aldrich</td>
			<td>93171</td>
			<td></td>
		</tr>
		<tr>
			<td>&#160;1,6-hexanediol</td>
			<td>Sigma&#8211;Aldrich</td>
			<td>240117</td>
			<td></td>
		</tr>
		<tr>
			<td>Neopentyl glycol</td>
			<td>Sigma&#8211;Aldrich</td>
			<td>408255</td>
			<td></td>
		</tr>
		<tr>
			<td>Adipic acid</td>
			<td>Sigma&#8211;Aldrich</td>
			<td>9582</td>
			<td></td>
		</tr>
		<tr>
			<td>anhydrous N,N-Dimethylformamide</td>
			<td>Sigma&#8211;Aldrich</td>
			<td>227056</td>
			<td></td>
		</tr>
		<tr>
			<td>Diethyl ether</td>
			<td>Sigma&#8211;Aldrich</td>
			<td>676845</td>
			<td></td>
		</tr>
		<tr>
			<td>titanium (IV) butoxide&#160;</td>
			<td>Sigma&#8211;Aldrich</td>
			<td>244112</td>
			<td></td>
		</tr>
		<tr>
			<td>1,4-butanediol&#160;</td>
			<td>Sigma&#8211;Aldrich</td>
			<td>493732</td>
			<td></td>
		</tr>
		<tr>
			<td>Vacuum oven</td>
			<td>Thermoscientific</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>4,4&#8217;-Methylenebis(phenyl isocyanate)</td>
			<td>Sigma&#8211;Aldrich</td>
			<td>101688</td>
			<td></td>
		</tr>
		<tr>
			<td>Tetrahydrofurane</td>
			<td>Sigma&#8211;Aldrich</td>
			<td>401757</td>
			<td></td>
		</tr>
		<tr>
			<td>Sputter coater</td>
			<td>Bal-Tec SCD 050</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td></td>
			<td></td>
			<td></td>
			<td>Inmunostaining</td>
		</tr>
		<tr>
			<td>Phosphate buffer saline (-MgCl2, -CaCl2)</td>
			<td>Gibco</td>
			<td>10010031</td>
			<td>&#160;Store at room temperature</td>
		</tr>
		<tr>
			<td>PBST, PBS made up with 0.1% TWEEN 20&#160;</td>
			<td>&#160; Scientific Laboratory Supplies Ltd</td>
			<td>EC607&#160;</td>
			<td></td>
		</tr>
		<tr>
			<td>Methanol</td>
			<td>&#160; Scientific Laboratory Supplies Ltd</td>
			<td>CHE5010</td>
			<td></td>
		</tr>
		<tr>
			<td>Bovine Serum Albumin</td>
			<td>Sigma-Aldrich, UK</td>
			<td>A7906</td>
			<td></td>
		</tr>
		<tr>
			<td>MOWIOL 488 DAPI</td>
			<td>Calbiochem</td>
			<td>475904</td>
			<td>Made up in Tris HCL and glycerol as per manufacturers instructions</td>
		</tr>
		<tr>
			<td></td>
			<td></td>
			<td></td>
			<td>Cell culture and Functional assay</td>
		</tr>
		<tr>
			<td>CYP3A activity pGLO kit</td>
			<td>Promega</td>
			<td>V8902</td>
			<td></td>
		</tr>
		<tr>
			<td>Hepatozyme</td>
			<td>Gibco</td>
			<td>17705021</td>
			<td></td>
		</tr>
		<tr>
			<td>TryLE express</td>
			<td>Life Technologies</td>
			<td><a href="http://www.lifetechnologies.com/order/catalog/product/12604013">12604013</a></td>
			<td></td>
		</tr>
	</tbody>
</table>

stabilizing hepatocellular phenotype using optimized synthetic surfaces

Currently, one of the major limitations in cell biology is maintaining differentiated cell phenotype. Biological matrices are commonly used for culturing and maintaining primary and pluripotent stem cell derived hepatocytes. While biological matrices are useful, they permit short term culture of hepatocytes, limiting their widespread application. We have attempted to overcome the limitations using a synthetic polymer coating. Polymers represent one of the broadest classes of biomaterials and possess a wide range of mechanical, physical and chemical properties, which can be fine-tuned for purpose. Importantly, such materials can be scaled to quality assured standards and display batch-to-batch consistency. This is essential if cells are to be expanded for high through-put screening in the pharmaceutical testing industry or for cellular based therapy. Polyurethanes (PUs) are one group of materials that have shown promise in cell culture. Our recent progress in optimizing a polyurethane coated surface, for long-term culture of human hepatocytes displaying stable phenotype, is presented and discussed.

Disolvente de polímero influye en la topografía de la superficie del polímero recubierto Poliuretano 134 se solubilizó en cloroformo, ya sea solo o en combinación con tolueno o tetrahidrofurano o diclorometano y los portaobjetos de vidrio mediante revestimiento por centrifugación con las diferentes formulaciones. Microscopía electrónica de barrido (SEM) y microscopía de fuerza atómica (AFM) se utilizaron para caracterizar las propiedades físicas de los revestimien...

Watch this Scientific Journal Video about Stabilizing Hepatocellular Phenotype Using Optimized Synthetic Surfaces at JoVE.com

Stabilizing Hepatocellular Phenotype Using Optimized Synthetic Surfaces

Este artículo se centrará en el desarrollo de superficies de polímero recubierto de largo plazo, la cultura estable de células madre derivadas de hepatocitos humanos.

Estabilizar hepatocelular Fenotipo Usando superficies sintéticas optimizadas

Currently, one of the major limitations in cell biology is maintaining differentiated cell phenotype. Biological matrices are commonly used for culturing ...

stabilizing-hepatocellular-phenotype-using-optimized-synthetic

Research

JoVE Journal

Chemistry

10.2K vistas.  University of Edinburgh.  Este artículo se centrará en el desarrollo de superficies de polímero recubierto de largo plazo, la cultura estable de células madre derivadas de hepatocitos humanos. 

Video: Stabilizing Hepatocellular Phenotype Using Optimized Synthetic Surfaces

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.

Unión covalente de BMP-2 en las superficies utilizando una monocapa enfoque de auto-ensamblada

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 ...

Investigación

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.

Hacia Biomimicking Madera: Fabricada en monobloque películas de nanocellulose, lignina, y una Policatión sintético

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

In Situ SIMS and IR Spectroscopy of Well-defined Surfaces Prepared by Soft Landing of Mass-selected Ions

Soft landing of mass-selected ions onto surfaces is a powerful approach for the highly-controlled preparation of materials that are inaccessible using conventional synthesis techniques. Coupling soft landing with in situ characterization using secondary ion mass spectrometry (SIMS) and infrared reflection absorption spectroscopy (IRRAS) enables analysis of well-defined surfaces under clean vacuum conditions. The capabilities of three soft-landing instruments constructed in our laboratory are illustrated for the representative system of surface-bound organometallics prepared by soft landing of mass-selected ruthenium tris(bipyridine) dications, [Ru(bpy)3]2+ (bpy = bipyridine), onto carboxylic acid terminated self-assembled monolayer surfaces on gold (COOH-SAMs). In situ time-of-flight (TOF)-SIMS provides insight into the reactivity of the soft-landed ions. In addition, the kinetics of charge reduction, neutralization and desorption occurring on the COOH-SAM both during and after ion soft landing are studied using in situ Fourier transform ion cyclotron resonance (FT-ICR)-SIMS measurements. In situ IRRAS experiments provide insight into how the structure of organic ligands surrounding metal centers is perturbed through immobilization of organometallic ions on COOH-SAM surfaces by soft landing. Collectively, the three instruments provide complementary information about the chemical composition, reactivity and structure of well-defined species supported on surfaces.

In Situ SIMS and IR Spectroscopy of Well-defined Surfaces Prepared by Soft Landing of Mass-selected Ions

Soft landing of mass-selected ions onto surfaces is a powerful approach for the highly-controlled preparation of novel materials. Coupled with analysis by in situ secondary ion mass spectrometry (SIMS) and infrared reflection absorption spectroscopy (IRRAS), soft landing provides unprecedented insights into the interactions of well-defined species with surfaces.

In Situ SIMS y espectroscopia IR de superficies bien definidas Preparado por Soft Landing de iones seleccionados-Mass

Soft landing of mass-selected ions onto surfaces is a powerful approach for the highly-controlled preparation of materials that are inaccessible using ...

Synthetic Methodology for Asymmetric Ferrocene Derived Bio-conjugate Systems via Solid Phase Resin-based Methodology

Early detection is a key to successful treatment of most diseases, and is particularly imperative for the diagnosis and treatment of many types of cancer. The most common techniques utilized are imaging modalities such as Magnetic Resonance Imaging (MRI), Positron Emission Topography (PET), and Computed Topography (CT) and are optimal for understanding the physical structure of the disease but can only be performed once every four to six weeks due to the use of imaging agents and overall cost. With this in mind, the development of &#8220;point of care&#8221; techniques, such as biosensors, which evaluate the stage of disease and/or efficacy of treatment in the clinician&#8217;s office and do so in a timely manner, would revolutionize treatment protocols.1 As a means to exploring ferrocene based biosensors for the detection of biologically relevant molecules2, methods were developed to produce ferrocene-biotin bio-conjugates described herein. This report will focus on a biotin-ferrocene-cysteine system that can be immobilized on a gold surface.

The synthesis of asymmetric species of ferrocene is challenging using solution techniques. This report focuses on the methods carried out to produce a ferrocene-biotin bioconjugate using facile and clean reactions accomplished via solid-phase synthesis. Incorporation of a thiolate moiety is shown to impart the ability for immobilization on gold surfaces.

Metodología sintética para asimétrica Ferroceno derivados Sistemas de Bio-conjugadas vía sólida metodología a base de resina de fase

Early detection is a key to successful treatment of most diseases, and is particularly imperative for the diagnosis and treatment of many types of cancer. ...

Optimization of Synthetic Proteins: Identification of Interpositional Dependencies Indicating Structurally and/or Functionally Linked Residues

Protein alignments are commonly used to evaluate the similarity of protein residues, and the derived consensus sequence used for identifying functional units (e.g., domains). Traditional consensus-building models fail to account for interpositional dependencies &#8211; functionally required covariation of residues that tend to appear simultaneously throughout evolution and across the phylogentic tree. These relationships can reveal important clues about the processes of protein folding, thermostability, and the formation of functional sites, which in turn can be used to inform the engineering of synthetic proteins. Unfortunately, these relationships essentially form sub-motifs which cannot be predicted by simple &#8220;majority rule&#8221; or even HMM-based consensus models, and the result can be a biologically invalid &#8220;consensus&#8221; which is not only never seen in nature but is less viable than any extant protein. We have developed a visual analytics tool, StickWRLD, which creates an interactive 3D representation of a protein alignment and clearly displays covarying residues. The user has the ability to pan and zoom, as well as dynamically change the statistical threshold underlying the identification of covariants. StickWRLD has previously been successfully used to identify functionally-required covarying residues in proteins such as Adenylate Kinase and in DNA sequences such as endonuclease target sites.

Synthetic protein sequences based on consensus motifs typically ignore co-evolving residues, that imply interpositional dependencies (IPDs). IPDs can be essential to activity, and designs that disregard them may result in suboptimal results. This protocol uses StickWRLD to identify IPDs and help inform rational protein design, resulting in more efficient results.

Optimización de las proteínas sintéticas: Identificación de interposicional Dependencias de indicación Estructuralmente y / o Residuos Funcionalmente Vinculados

Protein alignments are commonly used to evaluate the similarity of protein residues, and the derived consensus sequence used for identifying functional ...

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 ...

Color Spot Test As a Presumptive Tool for the Rapid Detection of Synthetic Cathinones

Synthetic cathinones are a large class of new psychoactive substances (NPS) that are increasingly prevalent in drug seizures made by law enforcement and other border protection agencies globally. Color testing is a presumptive identification technique indicating the presence or absence of a particular drug class using rapid and uncomplicated chemical methods. Owing to their relatively recent emergence, a color test for the specific identification of synthetic cathinones is not currently available. In this study, we introduce a protocol for the presumptive identification of synthetic cathinones, employing three aqueous reagent solutions: copper(II) nitrate, 2,9-dimethyl-1,10-phenanthroline (neocuproine) and sodium acetate. Small pin-head sized amounts (approximately 0.1-0.2 mg) of the suspected drugs are added to the wells of a porcelain spot plate, and each reagent is then added dropwise sequentially before heating on a hotplate. A color change from very light blue to yellow-orange after 10 min indicates the likely presence of synthetic cathinones. The highly stable and specific test reagent has the potential for use in the presumptive screening of unknown samples for synthetic cathinones in a forensic laboratory. However, the nuisance of an added heating step for the color change result limits the test to laboratory application and decreases the likelihood of an easy translation to field testing.

Here we present a simple, inexpensive, and selective chemical spot test protocol for the detection of synthetic cathinones, a class of new psychoactive substances. The protocol is suitable for use in various areas of law enforcement that encounter illicit material.

Prueba color como una herramienta presuntiva para la detección rápida de sintético Cathinones

Synthetic cathinones are a large class of new psychoactive substances (NPS) that are increasingly prevalent in drug seizures made by law enforcement and ...

Characterization of Synthetic Polymers via Matrix Assisted Laser Desorption Ionization Time of Flight (MALDI-TOF) Mass Spectrometry

There are many techniques that can be employed in the characterization of synthetic homopolymers, but few provide as useful of information for end group analysis as matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF MS). This tutorial demonstrates methods for optimization of the sample preparation, spectral acquisition, and data analysis of synthetic polymers using MALDI-TOF MS. Critical parameters during sample preparation include the selection of the matrix, identification of an appropriate cationization salt, and tuning the relative proportions of the matrix, cation, and analyte. The acquisition parameters, such as mode (linear or reflector), polarization (positive or negative), acceleration voltage, and delay time, are also important. Given some knowledge of the chemistry involved to synthesize the polymer and optimizing both the data acquisition parameters and the sample preparation conditions, spectra should be obtained with sufficient resolution and mass accuracy to enable the unambiguous determination of the end groups of most homopolymers (masses below 10,000) in addition to the repeat unit mass and the overall molecular weight distribution. Though demonstrated on a limited set of polymers, these general techniques are applicable to a much wider range of synthetic polymers for determining mass distributions, though end group determination is only possible for homopolymers with narrow dispersity.

Characterization of Synthetic Polymers via Matrix Assisted Laser Desorption Ionization Time of Flight MALDI-TOF Mass Spectrometry

A protocol for the matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF MS) characterization of synthetic polymers is described including the optimization of sample preparation, spectral acquisition, and data analysis.

Caracterización de polímeros sintéticos vía matriz asistida por láser desorción de ionización tiempo de vuelo (MALDI-TOF) espectrometría de masas

There are many techniques that can be employed in the characterization of synthetic homopolymers, but few provide as useful of information for end group ...

Light-driven Molecular Motors on Surfaces for Single Molecular Imaging

The design and synthesis of a synthetic system that aims for the direct visualization of a synthetic rotary motor at the single molecule level on surfaces are demonstrated. This work requires careful design, considerable synthetic effort, and proper analysis. The rotary motion of the molecular motor in solution is shown by 1H NMR and UV-vis absorption spectroscopy techniques. In addition, the method to graft the motor onto an amine-coated quartz is described. This method helps to gain more insight into molecular machines.

The manuscript describes how to synthesize and graft a molecular motor on surfaces for single molecular imaging.

Motores moleculares basadas en la luz en superficies para la proyección de imagen Molecular solo

The design and synthesis of a synthetic system that aims for the direct visualization of a synthetic rotary motor at the single molecule level on surfaces ...

A Facile Synthetic Method to Obtain Bismuth Oxyiodide Microspheres Highly Functional for the Photocatalytic Processes of Water Depuration

Bismuth oxyhalide (BiOI) is a promising material for sunlight-driven-environmental photocatalysis. Given that the physical structure of this kind of materials is highly related to its photocatalytic performance, it is necessary to standardize the synthetic methods in order to obtain the most functional architectures and, thus, the highest photocatalytic efficiency. Here, we report a reliable route to obtain BiOI microspheres via the solvothermal process, using Bi(NO3)3 and potassium iodide (KI) as precursors, and ethylene glycol as a template. The synthesis is standardized in a 150 mL autoclave, at 126 &#176;C for 18 h. This results in 2-3 &#181;m-sized mesoporous microspheres, with a relevant specific surface area (61.3 m2/g). Shortening the reaction times in the synthesis results in amorphous structures, while higher temperatures lead to a slight increase in the porosity of the microspheres, with no effect in the photocatalytic performance. The materials are photo-active under UV-A/visible light irradiation for the degradation of the antibiotic ciprofloxacin in water. This method has demonstrated to be effective in interlaboratory tests, obtaining similar BiOI microspheres in Mexican and Chilean research groups.

This article describes a synthetic method to obtain bismuth oxyiodide microspheres, which are highly functional to perform the photocatalytic removal of organic pollutants, such as ciprofloxacin, in water under UV-A/visible light irradiation.

Un fácil método sintético para obtener microesferas de Oxyiodide de bismuto altamente funcional para los procesos fotocatalíticos de depuración de aguas

Bismuth oxyhalide (BiOI) is a promising material for sunlight-driven-environmental photocatalysis. Given that the physical structure of this kind of ...