Este trabajo fue apoyado por la NSF / DOE Asociación de Ciencia y Tecnología Plasma (NSF Grant No. CBET-0853777 y el DOE el subsidio N º DE SC0001169), STTR Fase I del proyecto (NSF STTR Fase I No.1010133). Los autores desean agradecer al Programa de Investigación PPPL fuera del hotel con el apoyo de la Oficina de Ciencias de la Energía de Fusión para el apoyo a las experiencias de arco.

1. Preparación de ánodos <ol><li> Polvo de níquel escala (99,8%, 300 mesh) y el itrio en polvo (99,9%, malla 40), según la radio molar de 4,2:1 en forma de polvo catalizador. </li><li> Mezclar el polvo de catalizador con polvo de grafito (99,9995%, malla 200) muy bien. Rellene el polvo mezclado con varilla de grafito hueco (5 mm de diámetro exterior, 2,5 mm de diámetro interno y 75 mm de longitud) con firmeza. Asegúrese de que la radio molar total de C: Ni: Y en la barra del ánodo es 94.8:4.2:1, que es la relación óptima para sintetizar SWCNT 9. </li><li> Instalar la barra de cátodo (grafito puro, 13 mm de diámetro) y la barra del ánodo de peluche dentro de la cámara cilíndrica (acero inoxidable, 152 mm de diámetro y 254 mm de longitud). Ajuste la distancia de separación entre el cátodo y el ánodo a 3 mm. </li></ol> 2. Sustrato de configuración <ol><li> Coloque un imán permanente cuboides (25 mm × 25 mm × 100 mm) dentro de la cámara a unos 25 mm de distancia desde el eje de los electrodos. El Ultra-High-Temp Alnico imán utilizadoen el experimento tiene el peso de 650 gramos. Utilice la configuración cuando la brecha entre los electrodos se colocan a una distancia de alrededor de h = 75 mm (Figura 1a) de la parte inferior del imán permanente. </li><li> Cortar la hoja de 0,3 mm de espesor de molibdeno (99,95%) como el de 25 mm x 100 mm forma rectangular. Eliminar la contaminación superficial por dismembrator ultrasonido en acetona y etanol durante 30 minutos con una amplitud de 50% de ultrasonidos, 150 w de potencia de salida y 40 kHz de frecuencia. </li><li> Instale la hoja de molibdeno conectar un lado del imán permanente, y convertir este lado hacia los electrodos. </li><li> Medir el campo magnético en el espacio entre los electrodos por un Gaussmeter. Mantener el campo magnético promedio entre los electrodos es de 0,06 T. </li></ol> 3. Ignición de arco de plasma <ol><li> De bombeo de la cámara cilíndrica a la presión de menos de 10 -1 Torr vacío y luego se llena con helio (99,995%) y 500 Torr. </li><li> Conectar los electrodos de arco de DC welding fuente de alimentación y establecer la fuente de alimentación de corriente de arco de unos 75 A. </li><li> Registre los valores en tiempo real de la corriente de arco de tensión de arco, y la presión de la cámara para el análisis post-experimento. </li><li> Ver el video de arco de las ventanas derecha y de adelante por dos cámaras digitales simultáneamente. Las instantáneas después de 1 segundo de arco de partida se muestran en la Figura 1b (de derecha ventana) y Figura 1d (del visor). </li><li> Ejecute el arco de 15 segundos. Enfriar la cámara por convección natural, por lo menos 20 minutos. </li></ol> 4. Después de la síntesis de análisis y caracterización <ol><li> Use unas pinzas para arrancar las escamas de la deposición de la superficie de la hoja de molibdeno en el que se dirige el chorro de arco de plasma. Otra muestra se recoge desde el cuello negro del cátodo. Observar la morfología de ambos lados de escamas de deposición bajo SEM (voltaje de aceleración de 30 KV se utilizó). </li><li> En cuanto a la preparación de muestras para<html> TEM análisis, las películas delgadas de la muestra se obtuvieron mediante la caída de fundición de una suspensión de metanol-solución SWCNT dispersos después de ultrasonidos durante 60 minutos usando dismembrator ultrasonidos con 50% de ultrasonidos amplitud. Observar la morfología de la película delgada en JEOL TEM con la tensión de 100 KV después de la volatilización de una solución de metanol. Para la posición de interés en la muestra, el patrón de difracción de electrones se pueden obtener con la longitud de la cámara CCD de 50 cm asociado con TEM. </li><li> La espectroscopia Raman se llevó a cabo en un sistema de micro-Raman basado en un 200 mW Lexel 3000 Ar láser de ion (de salida ajustable sola línea), con la óptica holográfica, un espectrómetro de 0,5 m y un nitrógeno líquido refrigerado detector CCD, la longitud de onda 514 nm, que corresponde a la de energía de 2.33 eV. Mediciones Raman cubierto el rango de 100 cm -1 a 3100 cm -1, y se llevaron a cabo en la superficie de copos de grafeno. </li></ol> 5. Resultados representante &quot;&gt; Las instantáneas de vídeo obtenidas de forma simultánea desde ventanas derecho y frontal de la cámara se muestran en la Figura 1b, d de h = 75 mm. Estas imágenes ilustran perturbación significativa de la columna de arco de plasma en presencia de un campo magnético externo en comparación con la columna del arco simetría axial observado en el caso sin un campo magnético 10. Figura 2a y 2b muestra la morfología típica de las partículas y el catalizador SWCNT recogidos en el cuello de cátodo sin campo magnético y el campo magnético de B = 0,06 Tesla en TEM, respectivamente. Se puede observar que SWCNT con el campo magnético son apretadas en manojos con diámetros que van de 2 a 20 nm debido a la interacción de van der Waals entre SWCNT individual. En comparación, el SWCNT sin campo magnético tienen el diámetro más grande de paquetes y de mayor diámetro individual, lo cual es consistente con el análisis del espectro Raman. Además, el campo magnético can dar lugar a la SWCNT con mayor pureza se muestra en la Figura 2a y 2b. La influencia más interesante del campo magnético es que los copos de grafeno puede ser obtenida de la superficie de las escamas de la deposición, que está cerca a la hoja de molibdeno en el mismo proceso. Figura 2c y 2d muestran el SEM y TEM imágenes de copos de grafeno, así como unos pocos- grafeno capa obtenida a partir de la muestra tomada en el lugar correspondieron a aviones de arco de plasma. La inserción de la figura 2d muestra el patrón de difracción de electrones asociados con el grafeno. El patrón hexagonal puntos de difracción de electrones se presenta la evidencia de las estructuras cristalinas bien ordenada. Espectro Raman es una poderosa herramienta para la caracterización de los copos de grafeno y SWCNT. Los picos típicos observados en el grafeno son los picos G y 2D a ~ 1600 cm -1 y ~ 2700 cm -1, respectivamente, con la longitud de onda de excitación de 514 nm. El Gpico se debe a las vibraciones en el avión que se puede observar en todos los materiales de carbono sp2. El pico 2D es una de segundo orden del pico de D, pero se ve incluso en sistemas que no son desordenados, debido a los fonones cuarto fin de impulso al proceso de cambio de doble resonancia. Desempeña un papel crucial en la caracterización de grafeno. La intensidad I (2D) / I (G) es de aproximadamente 4 de grafeno monocapa y disminuye con la adición de capas posteriores, por lo que es posible estimar el espesor de las capas de grafeno. 11 Figura 3 indica que el valor de I (2D) / I (G) es de alrededor de 1, que puede ser la evidencia de las pocas capas de grafeno. El modo de respiración radial (RBM) entre 120 y 350 cm -1 en el espectro Raman se pueden utilizar para identificar el diámetro de los nanotubos a través de la frecuencia de vibración coherente de los átomos de C en la dirección radial. La relación experimental entre la frecuencia y el diámetro es SWCNT RBM ω = A / d t + B, donde el o los parámetrosf A e igual a 234 y 10 cm-1 B, respectivamente, para el SWCNT típica forma de paquetes. De la Figura 3, las frecuencias de RBM SWCNT con y sin campo magnético son 163,8 y 215,2 cm-1, que corresponde a los diámetros SWCNT individual media de 1,52 y 1,14 nm, respectivamente. <img alt="Figura 1." src="/files/ftp_upload/3455/3455fig1.jpg" /> Figura 1. Distribución del campo magnético de simulación por software FEMM 4.2 (a), fotografía de arco de plasma chorro de la derecha del viewport (b), diagrama esquemático de la posición de los electrodos y el campo magnético de dirección en la brecha para el caso en que la brecha entre los electrodos se coloca unos 75 mm por encima del fondo de imán permanente (c), y una fotografía del arco chorro de plasma de la vista Frontal (d). <img alt="Figura 2." src="/files/ftp_upload/3455/3455fig2.jpg" /> Figura 2. Imagen representativa de TEM como de síntesisPaquetes SWCNT sin campo magnético (a) y los paquetes SWCNT con el campo magnético (b), típica imagen de SEM de copos de grafeno sintetizado con el campo magnético (c), y la imagen de TEM de grafeno con el campo magnético. El recuadro es el electrón área seleccionada patrón de difracción muestra la estructura cristalina de grafeno. <img alt="Figura 3." src="/files/ftp_upload/3455/3455fig3.jpg" /> Figura 3. Espectro Raman de las muestras con el campo magnético en el rango de 100 a 3100 cm -1. Recuadro: espectro Raman de las muestras sin campo magnético alrededor de las frecuencias de la RBM. <img alt="Figura 4." src="/files/ftp_upload/3455/3455fig4.jpg" /> Figura 4. Nanoestructura región el crecimiento y la densidad del número de carbono y el níquel para el arco de la Nota A. 60 que las densidades de carbono y el níquel se muestra en el lado izquierdo y derecho de los electrodos, coexisten en la misma región.

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No tenemos nada que revelar.

En las instantáneas de vídeo se muestra en la Figura 1b y 1d, para el caso de que la brecha entre los electrodos se colocan a una distancia de aproximadamente h = 75 mm desde el fondo de imán permanente, hay que señalar que el cambio de posición del imán (que probamos cambio imán a lo largo de los resultados del eje z, y girando el imán sobre) en la desviación del flujo de chorro de arco en la dirección x que corresponde a la dirección de la fuerza J x B se ilustra en la <str...

Tabla de reactivos y equipos específicos: <table border="1"><tbody><tr><th> Nombre del reactivo </th><th> Empresa </th><th> Número de catálogo </th><th> Comentarios (opcional) </th></tr><tr><td> Metanol </td><td> Acros orgánicos </td><td> 423950010 </td><td></td></tr><tr><td> Níquel en polvo </td><td> Alfa Aesar </td><td> 10581 </td><td></td></tr><tr><td> Itrio en polvo </td><td> Acros orgánicos </td><td> 318060050 </td><td></td></tr><tr><td> Polvo de grafito </td><td> Alfa Aesar </td><td> 40799 </td><td></td></tr><tr><td> Hueca caña de grafito </td><td> Saturno Industrias </td><td> POCO EDM 3 </td><td></td></tr><tr><td> Imán permanente </td><td> McMaster-Carr </td><td> 57315K51 </td><td></td></tr><tr><td> Molibdeno hoja </td><td> Dingqi Ciencia. y Tecnología. </td><td> 080504-11 </td><td></td&gt; </tr><tr><td> Ultrasónico dismembrator </td><td> Fisher Scientific </td><td> Modelo 150T </td><td></td></tr><tr><td> De efecto Hall Gaussmeter </td><td> AI </td><td> Modelo 100 </td><td></td></tr><tr><td> Fuente de alimentación de soldadura </td><td> Miller Electric </td><td> Gold Star 600SS </td><td></td></tr><tr><td> Bomba de vacío </td><td> J / B </td><td> DV-85N </td><td></td></tr><tr><td> SEM </td><td> Zeiss </td><td> LEO 1430VP </td><td></td></tr><tr><td> TEM </td><td> JEOL </td><td> 1200 EX </td><td></td></tr><tr><td> Raman </td><td> Horiba </td><td> HR800 </td><td></td></tr></tbody></table>

simultaneous synthesis of single-walled carbon nanotubes and graphene in a magnetically-enhanced arc plasma

Nanoestructuras de carbono como los nanotubos de carbono de pared simple (SWCNT) y el grafeno atraer a un diluvio de interés de los estudiosos en la actualidad debido a su aplicación muy prometedora para sensores moleculares, transistores de efecto de campo y super dispositivos electrónicos delgados y flexibles 4.1. Descarga de arco anódica con el apoyo de la erosión del material del ánodo es uno de los métodos más prácticos y eficientes, que pueden proporcionar información específica de no-equilibrio los procesos y una gran afluencia de materiales de carbono para el desarrollo de estructuras a una temperatura relativamente alta, y por lo tanto el as- sintetizados tienen pocos defectos estructurales y una mejor cristalinidad. Para mejorar aún más la capacidad de control y la flexibilidad de la síntesis de nanoestructuras de carbono en el arco de descarga, los campos magnéticos pueden ser aplicados durante el proceso de síntesis de acuerdo con las fuertes respuestas magnéticas de plasmas de arco. Se demostró que el mayor arco magnético-Discharge puede aumentar la duración media de SWCNT 5, reducir la distribución del diámetro de las partículas del catalizador metálico y 6 de los nanotubos de carbono, y cambiar la relación de los metálicos y semiconductores 7 nanotubos de carbono, así como llevar a la síntesis de grafeno 8. Por otra parte, vale la pena señalar que cuando se introduce un campo magnético no uniforme con la componente normal de la corriente en el arco, la fuerza de Lorentz a lo largo de la dirección de J × B puede generar el chorro de plasma y hacer la entrega efectiva de las partículas de iones de carbono y flujo de calor a las muestras. Como resultado, los grandes copos de grafeno de alta pureza y nanotubos de carbono se han generado simultáneamente por tales nuevo método de arco magnético mejorada anódico. Arco de imágenes, microscopía electrónica de barrido (SEM), microscopio electrónico de transmisión (TEM) y la espectroscopia Raman fueron empleados para analizar la caracterización de nanoestructuras de carbono. Estos resultados indican unaamplio espectro de oportunidades para manipular las propiedades de nanoestructuras producidas en plasmas por medio de controlar las condiciones de arco.

Watch this Scientific Journal Video about Simultaneous Synthesis of Single-walled Carbon Nanotubes and Graphene in a Magnetically-enhanced Arc Plasma at JoVE.com

Simultaneous Synthesis of Single-walled Carbon Nanotubes and Graphene in a Magnetically-enhanced Arc Plasma

Descarga de arco anódica es uno de los métodos más prácticos y eficaces para sintetizar nanoestructuras de carbono diferentes. Para aumentar la capacidad de control del arco y la flexibilidad, un campo magnético no uniforme fue presentado a proceso de la síntesis de un solo paso de copos de grafeno a gran escala y de alta pureza nanotubos de carbono.

Síntesis simultánea de los nanotubos de carbono de pared simple y grafeno en un arco de plasma magnético mejorada

Carbon nanostructures such as single-walled carbon nanotubes (SWCNT) and graphene attract a deluge of interest of scholars nowadays due to their very ...

simultaneous-synthesis-single-walled-carbon-nanotubes-graphene

Research

JoVE Journal

Bioengineering

15.2K vistas.  The George Washington University. Descarga de arco anódica es uno de los métodos más prácticos y eficaces para sintetizar nanoestructuras de carbono diferentes. Para aumentar la capacidad de control del arco y la flexibilidad, un campo magnético no uniforme fue presentado a proceso de la síntesis de un solo paso de copos de grafeno a gran escala y de alta pureza nanotubos de carbono.

Video: Simultaneous Synthesis of Single-walled Carbon Nanotubes and Graphene in a Magnetically-enhanced Arc Plasma

Graphene Coatings for Biomedical Implants

Atomically smooth graphene as a surface coating has potential to improve implant properties. This demonstrates a method for coating nitinol alloys with nanometer thick layers of graphene for applications as a stent material. Graphene was grown on copper substrates via chemical vapor deposition and then transferred onto nitinol substrates. In order to understand how the graphene coating could change biological response, cell viability of rat aortic endothelial cells and rat aortic smooth muscle cells was investigated. Moreover, the effect of graphene-coatings on cell adhesion and morphology was examined with fluorescent confocal microscopy. Cells were stained for actin and nuclei, and there were noticeable differences between pristine nitinol samples compared to graphene-coated samples. Total actin expression from rat aortic smooth muscle cells was found using western blot. Protein adsorption characteristics, an indicator for potential thrombogenicity, were determined for serum albumin and fibrinogen with gel electrophoresis. Moreover, the transfer of charge from fibrinogen to substrate was deduced using Raman spectroscopy. It was found that graphene coating on nitinol substrates met the functional requirements for a stent material and improved the biological response compared to uncoated nitinol. Thus, graphene-coated nitinol is a viable candidate for a stent material.

Graphene offers potential as a coating material for biomedical implants. In this study we demonstrate a method for coating nitinol alloys with nanometer thick layers of graphene and determine how graphene may influence implant response.

Revestimientos de grafeno para Implantes Biomédicos

Atomically smooth graphene as a surface coating has potential to improve implant properties. This demonstrates a method for coating nitinol alloys with ...

Investigación

Bioingeniería

Localization and Relative Quantification of Carbon Nanotubes in Cells with Multispectral Imaging Flow Cytometry

Carbon-based nanomaterials, like carbon nanotubes (CNTs), belong to this type of nanoparticles which are very difficult to discriminate from carbon-rich cell structures and de facto there is still no quantitative method to assess their distribution at cell and tissue levels. What we propose here is an innovative method allowing the detection and quantification of CNTs in cells using a multispectral imaging flow cytometer (ImageStream, Amnis). This newly developed device integrates both a high-throughput of cells and high resolution imaging, providing thus images for each cell directly in flow and therefore statistically relevant image analysis. Each cell image is acquired on bright-field (BF), dark-field (DF), and fluorescent channels, giving access respectively to the level and the distribution of light absorption, light scattered and fluorescence for each cell. The analysis consists then in a pixel-by-pixel comparison of each image, of the 7,000-10,000 cells acquired for each condition of the experiment. Localization and quantification of CNTs is made possible thanks to some particular intrinsic properties of CNTs: strong light absorbance and scattering; indeed CNTs appear as strongly absorbed dark spots on BF and bright spots on DF with a precise colocalization.
This methodology could have a considerable impact on studies about interactions between nanomaterials and cells given that this protocol is applicable for a large range of nanomaterials, insofar as they are capable of absorbing (and/or scattering) strongly enough the light.

In this study, the main purpose was to monitor the cellular uptake and eventual exocytosis of carbon nanotubes (CNTs). From this perspective, we proposed here a unique method using multispectral imaging flow cytometry allowing a quantification and localization of CNTs in a statistically relevant number of cells.

Localización y cuantificación relativa de nanotubos de carbono en las células con multiespectral de imágenes de Citometría de Flujo

Carbon-based nanomaterials, like carbon nanotubes (CNTs), belong to this type of nanoparticles which are very difficult to discriminate from carbon-rich ...

Synthesis of an Intein-mediated Artificial Protein Hydrogel

We present the synthesis of a highly stable protein hydrogel mediated by a split-intein-catalyzed protein trans-splicing reaction. The building blocks of this hydrogel are two protein block-copolymers each containing a subunit of a trimeric protein that serves as a crosslinker and one half of a split intein. A highly hydrophilic random coil is inserted into one of the block-copolymers for water retention. Mixing of the two protein block copolymers triggers an intein trans-splicing reaction, yielding a polypeptide unit with crosslinkers at either end that rapidly self-assembles into a hydrogel. This hydrogel is very stable under both acidic and basic conditions, at temperatures up to 50 &#176;C, and in organic solvents. The hydrogel rapidly reforms after shear-induced rupture. Incorporation of a &#34;docking station peptide&#34; into the hydrogel building block enables convenient incorporation of &#34;docking protein&#34;-tagged target proteins. The hydrogel is compatible with tissue culture growth media, supports the diffusion of 20 kDa molecules, and enables the immobilization of bioactive globular proteins. The application of the intein-mediated protein hydrogel as an organic-solvent-compatible biocatalyst was demonstrated by encapsulating the horseradish peroxidase enzyme and corroborating its activity.

We present the synthesis of a split-intein-mediated protein hydrogel. The building blocks of this hydrogel are two protein copolymers each containing a subunit of a trimeric protein that serves as a crosslinker and one half of a split intein. Mixing of the two protein copolymers triggers an intein trans-splicing reaction, yielding a polypeptide unit that self-assembles into a hydrogel. This hydrogel is highly pH- and temperature-stable, compatible with organic solvents, and easily incorporates functional globular proteins.

Síntesis de una proteína artificial mediada Intein hidrogel

We present the synthesis of a highly stable protein hydrogel mediated by a split-intein-catalyzed protein trans-splicing reaction. The building blocks of ...

Synthesis of Keratin-based Nanofiber for Biomedical Engineering

Electrospinning, due to its versatility and potential for applications in various fields, is being frequently used to fabricate nanofibers. Production of these porous nanofibers is of great interest due to their unique physiochemical properties. Here we elaborate on the fabrication of keratin containing poly (&#949;-caprolactone) (PCL) nanofibers (i.e., PCL/keratin composite fiber). Water soluble keratin was first extracted from human hair and mixed with PCL in different ratios. The blended solution of PCL/keratin was transformed into nanofibrous membranes using a laboratory designed electrospinning set up. Fiber morphology and mechanical properties of the obtained nanofiber were observed and measured using scanning electron microscopy and tensile tester. Furthermore, degradability and chemical properties of the nanofiber were studied by FTIR. SEM images showed uniform surface morphology for PCL/keratin fibers of different compositions. These PCL/keratin fibers also showed excellent mechanical properties such as Young&#39;s modulus and failure point. Fibroblast cells were able to attach and proliferate thus proving good cell viability. Based on the characteristics discussed above, we can strongly argue that the blended nanofibers of natural and synthetic polymers can represent an excellent development of composite materials that can be used for different biomedical applications.

Electrospun nanofibers have a high surface area to weight ratio, excellent mechanical integrity, and support cell growth and proliferation. These nanofibers have a wide range of biomedical applications. Here we fabricate keratin/ PCL nanofibers, using the electrospinning technique, and characterize the fibers for possible applications in tissue engineering.

Síntesis de nanofibras a base de Queratina de Ingeniería Biomédica

Electrospinning, due to its versatility and potential for applications in various fields, is being frequently used to fabricate nanofibers. Production of ...

Engineering Molecular Recognition with Bio-mimetic Polymers on Single Walled Carbon Nanotubes

Semiconducting single-wall carbon nanotubes (SWNTs) are a class of optically active nanomaterial that fluoresce in the near infrared, coinciding with the optical window where biological samples are most transparent. Here, we outline techniques to adsorb amphiphilic polymers and polynucleic acids onto the surface of SWNTs to engineer their corona phases and create novel molecular sensors for small molecules and proteins. These functionalized SWNT sensors are both biocompatible and stable. Polymers are adsorbed onto the nanotube surface either by direct sonication of SWNTs and polymer or by suspending SWNTs using a surfactant followed by dialysis with polymer. The fluorescence emission, stability, and response of these sensors to target analytes are confirmed using absorbance and near-infrared fluorescence spectroscopy. Furthermore, we demonstrate surface immobilization of the sensors onto glass slides to enable single-molecule fluorescence microscopy to characterize polymer adsorption and analyte binding kinetics.

We present a protocol for engineering the corona phase of near infrared fluorescent single walled carbon nanotubes (SWNTs) using amphiphilic polymers and DNA to develop sensors for molecular targets without known recognition elements.

Ingeniería Molecular Recognition con polímeros biomiméticos en una sola pared nanotubos de carbono

Semiconducting single-wall carbon nanotubes (SWNTs) are a class of optically active nanomaterial that fluoresce in the near infrared, coinciding with the ...

Targeted Plasma Membrane Delivery of a Hydrophobic Cargo Encapsulated in a Liquid Crystal Nanoparticle Carrier

The controlled delivery of drug/imaging agents to cells is critical for the development of therapeutics and for the study of cellular signaling processes. Recently, nanoparticles (NPs) have shown significant promise in the development of such delivery systems. Here, a liquid crystal NP (LCNP)-based delivery system has been employed for the controlled delivery of a water-insoluble dye, 3,3&#8242;-dioctadecyloxacarbocyanine perchlorate (DiO), from within the NP core to the hydrophobic region of a plasma membrane bilayer. During the synthesis of the NPs, the dye was efficiently incorporated into the hydrophobic LCNP core, as confirmed by multiple spectroscopic analyses. Conjugation of a PEGylated cholesterol derivative to the NP surface (DiO-LCNP-PEG-Chol) enabled the binding of the dye-loaded NPs to the plasma membrane in HEK 293T/17 cells. Time-resolved laser scanning confocal microscopy and F&#246;rster resonance energy transfer (FRET) imaging confirmed the passive efflux of DiO from the LCNP core and its insertion into the plasma membrane bilayer. Finally, the delivery of DiO as a LCNP-PEG-Chol attenuated the cytotoxicity of DiO; the NP form of DiO exhibited ~30-40% less toxicity compared to DiOfree delivered from bulk solution. This approach demonstrates the utility of the LCNP platform as an efficient modality for the membrane-specific delivery and modulation of hydrophobic molecular cargos.

A liquid crystal nanoparticle (LCNP) nanocarrier is exploited as a vehicle for the controlled delivery of a hydrophobic cargo to the plasma membrane of living cells.

Targeted membrana plasmática Entrega de cargo encapsulado hidrofóbico en un cristal líquido portador de nanopartículas

The controlled delivery of drug/imaging agents to cells is critical for the development of therapeutics and for the study of cellular signaling processes. ...

DNA Nanotubes as a Versatile Tool to Study Semiflexible Polymers

Mechanical properties of complex, polymer-based soft matter, such as cells or biopolymer networks, can be understood in neither the classical frame of flexible polymers nor of rigid rods. Underlying filaments remain outstretched due to their non-vanishing backbone stiffness, which is quantified via the persistence length (lp), but they are also subject to strong thermal fluctuations. Their finite bending stiffness leads to unique, non-trivial collective mechanics of bulk networks, enabling the formation of stable scaffolds at low volume fractions while providing large mesh sizes. This underlying principle is prevalent in nature (e.g., in cells or tissues), minimizing the high molecular content and thereby facilitating diffusive or active transport. Due to their biological implications and potential technological applications in biocompatible hydrogels, semiflexible polymers have been subject to considerable study. However, comprehensible investigations remained challenging since they relied on natural polymers, such as actin filaments, which are not freely tunable. Despite these limitations and due to the lack of synthetic, mechanically tunable, and semiflexible polymers, actin filaments were established as the common model system. A major limitation is that the central quantity lp cannot be freely tuned to study its impact on macroscopic bulk structures. This limitation was resolved by employing structurally programmable DNA nanotubes, enabling controlled alteration of the filament stiffness. They are formed through tile-based designs, where a discrete set of partially complementary strands hybridize in a ring structure with a discrete circumference. These rings feature sticky ends, enabling the effective polymerization into filaments several microns in length, and display similar polymerization kinetics as natural biopolymers. Due to their programmable mechanics, these tubes are versatile, novel tools to study the impact of lp on the single-molecule as well as the bulk scale. In contrast to actin filaments, they remain stable over weeks, without notable degeneration, and their handling is comparably straightforward.

Semiflexible polymers display unique mechanical properties that are extensively applied by living systems. However, systematic studies on biopolymers are limited since properties such as polymer rigidity are inaccessible. This manuscript describes how this limitation is circumvented by programmable DNA nanotubes, enabling experimental studies on the impact of filament rigidity.

Nanotubos de ADN como una herramienta versátil para el estudio de polímeros Semiflexible

Mechanical properties of complex, polymer-based soft matter, such as cells or biopolymer networks, can be understood in neither the classical frame of ...

Melt Electrospinning Writing of Three-dimensional Poly(&#949;-caprolactone) Scaffolds with Controllable Morphologies for Tissue Engineering Applications

This tutorial reflects on the fundamental principles and guidelines for electrospinning writing with polymer melts, an additive manufacturing technology with great potential for biomedical applications. The technique facilitates the direct deposition of biocompatible polymer fibers to fabricate well-ordered scaffolds in the sub-micron to micro scale range. The establishment of a stable, viscoelastic, polymer jet between a spinneret and a collector is achieved using an applied voltage and can be direct-written. A significant benefit of a typical porous scaffold is a high surface-to-volume ratio which provides increased effective adhesion sites for cell attachment and growth. Controlling the printing process by fine-tuning the system parameters enables high reproducibility in the quality of the printed scaffolds. It also provides a flexible manufacturing platform for users to tailor the morphological structures of the scaffolds to their specific requirements. For this purpose, we present a protocol to obtain different fiber diameters using melt electrospinning writing (MEW) with a guided amendment of the parameters, including flow rate, voltage and collection speed. Furthermore, we demonstrate how to optimize the jet, discuss often experienced technical challenges, explain troubleshooting techniques and showcase a wide range of printable scaffold architectures.

Melt Electrospinning Writing of Three-dimensional Poly(&amp;#949;-caprolactone) Scaffolds with Controllable Morphologies for Tissue Engineering Applications

This protocol serves as a comprehensive guideline to fabricate scaffolds via electrospinning with polymer melts in a direct writing mode. We systematically outline the process and define the appropriate parameter settings for achieving targeted scaffold architectures.

Escritura de Electrospinning de andamios Poly(ε-caprolactone) tridimensional con morfologías controlables para aplicaciones de ingeniería de tejidos del derretimiento

This tutorial reflects on the fundamental principles and guidelines for electrospinning writing with polymer melts, an additive manufacturing technology ...

Microhoneycomb Monoliths Prepared by the Unidirectional Freeze-drying of Cellulose Nanofiber Based Sols: Method and Extensions

Monolithic honeycomb structures have been attractive to multidisciplinary fields due to their high strength-to-weight ratio. Particularly, microhoneycomb monoliths (MHMs) with micrometer-scale channels are expected as efficient platforms for reactions and separations because of their large surface areas. Up to now, MHMs have been prepared by a unidirectional freeze-drying (UDF) method only from very limited precursors. Herein, we report a protocol from which a series of MHMs consisting of different components can be obtained. Recently, we found that cellulose nanofibers function as a distinct structure-directing agent towards the formation of MHMs through the UDF process. By mixing the cellulose nanofibers with water soluble substances which do not yield MHMs, a variety of composite MHMs can be prepared. This significantly enriches the chemical constitution of MHMs towards versatile applications.

Here, we present a general protocol to prepare a variety of microhoneycomb monoliths (MHMs) in which fluid can pass through with an extremely low pressure drop. MHMs obtained are expected to be used as filters, catalyst supports, flow-type electrodes, sensors and scaffolds for biomaterials.

Monolitos de Microhoneycomb preparados por la liofilización unidireccional de nanofibras de celulosa basan Sols: método y extensiones

Monolithic honeycomb structures have been attractive to multidisciplinary fields due to their high strength-to-weight ratio. Particularly, microhoneycomb ...

Synthesis of Multi-walled Carbon Nanotubes Modified with Silver Nanoparticles and Evaluation of Their Antibacterial Activities and Cytotoxic Properties

In this study, multi-walled carbon nanotubes (MWCNTs) were treated with an aqueous sulfuric acid solution to form an oxygen-based functional group. Silver MWCNTs were prepared by the reductive deposition of silver from an aqueous solution of AgNO3 on the oxidized MWCNTs. Given the unique color of the CNTs, it was not possible to apply them to the minimum inhibitory concentration or mitochondrial toxicity assays to evaluate the toxicity and antibacterial properties, since they would interfere with the assays. The inhibition zone and minimum bactericidal concentration for the Ag-MWCNTs were measured and Live/Dead and Trypan Blue assays were used to measure the toxicity and antibacterial properties without interfering with the color of the CNTs.

In this study, antimicrobial nanomaterials were synthesized by acidic oxidation of multiwalled carbon nanotubes and subsequent reductive deposition of silver nanoparticles. Antimicrobial activity and cytotoxicity tests were performed with the as-prepared nanomaterials.

Síntesis de nanotubos de carbono multipared modificados con nanopartículas de plata y la evaluación de sus actividades antibacterianas y propiedades citotóxicas

In this study, multi-walled carbon nanotubes (MWCNTs) were treated with an aqueous sulfuric acid solution to form an oxygen-based functional group. Silver ...