Este trabajo fue apoyado por JCO A * STAR Investigatorship conceder (proyecto Nº 1437 00135), A * STAR ciencia e Ingeniería Consejo Sector público financiación de la investigación (proyecto no. 1421200076) y un proyectos de investigación conjuntos de JSP-NUS conceden (WBS R143-000-611-133).

<ol>
	<li>Figuerola, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=End-to-End+Assembly+of+Shape-Controlled+Nanocrystals+via+a+Nanowelding+Approach+Mediated+by+Gold+Domains.">End-to-End Assembly of Shape-Controlled Nanocrystals via a Nanowelding Approach Mediated by Gold Domains.</a> Adv. Mat. 21, 550-554 (2009).</li><li>Tang, Z., Kotov, N. A., Giersig, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Spontaneous+Organization+of+Single+CdTe+Nanoparticles+into+Luminescent+Nanowires.">Spontaneous Organization of Single CdTe Nanoparticles into Luminescent Nanowires.</a> Science. 297, 237-240 (2002).</li><li>Kim, D., Kim, W. D., Kang, M. S., Kim, S. -. H., Lee, D. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Self-Organization+of+Nanorods+into+Ultra-Long+Range+Two-Dimensional+Monolayer+End-to-End+Network.">Self-Organization of Nanorods into Ultra-Long Range Two-Dimensional Monolayer End-to-End Network.</a> Nano Lett. 15, 714-720 (2015).</li><li>Schliehe, C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ultrathin+PbS+Sheets+by+Two-Dimensional+Oriented+Attachment.">Ultrathin PbS Sheets by Two-Dimensional Oriented Attachment.</a> Science. 329, 550-553 (2010).</li><li>Chakrabortty, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Facet+to+facet+Linking+of+Shape+Anisotropic+Inorganic+Nanocrystals+with+Site+Specific+and+Stoichiometric+Control.">Facet to facet Linking of Shape Anisotropic Inorganic Nanocrystals with Site Specific and Stoichiometric Control.</a> Nano Lett. 16, 6431-6436 (2016).</li><li>Leatherdale, C. A., Woo, W. K., Mikulec, F. V., Bawendi, M. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=On+the+Absorption+Cross+Section+of+CdSe+Nanocrystal+Quantum+Dots.">On the Absorption Cross Section of CdSe Nanocrystal Quantum Dots.</a> J Phys Chem B. 106, 7619-7622 (2002).</li><li>Dabbousi, B. O., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=(CdSe)ZnS+Core-Shell+Quantum+Dots:+Synthesis+and+Characterization+of+a+Size+Series+of+Highly+Luminescent+Nanocrystallites.">(CdSe)ZnS Core-Shell Quantum Dots: Synthesis and Characterization of a Size Series of Highly Luminescent Nanocrystallites.</a> J Phys Chem B. 101, 9463-9475 (1997).</li><li>Carbone, L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Synthesis+and+Micrometer-Scale+Assembly+of+Coilloidal+CdSe/CdS+Nanorods+Prepared+by+Seeded+Grwoth+Approach.">Synthesis and Micrometer-Scale Assembly of Coilloidal CdSe/CdS Nanorods Prepared by Seeded Grwoth Approach.</a> Nano Lett. 7, 2942-2950 (2007).</li><li>Shaviv, E., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Absorption+properties+of+Metal-Semiconductor+Hybrid+Nanoparticles.">Absorption properties of Metal-Semiconductor Hybrid Nanoparticles.</a> ACS Nano. 5, 4712-4719 (2011).</li><li>Lim, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Controlled+Synthesis+of+CdSe+Tetrapods+with+High+Morphological+Uniformity+by+the+Persistent+Kinetic+Growth+and+the+Halide-Mediated+Phase+Transformation.">Controlled Synthesis of CdSe Tetrapods with High Morphological Uniformity by the Persistent Kinetic Growth and the Halide-Mediated Phase Transformation.</a> Chem Mat. 25, 1443-1449 (2013).</li></ol>

No tenemos nada que revelar.

La vinculación técnica descrita en este trabajo permite cadmio forma anisotrópica calcógeno nanopartículas que pueden experimentar intercambio catiónico con Ag+ que se ensamblarán, faceta a faceta, en montajes como cadenas lineales o ramificadas redes. Fracaso para formar asambleas bien dispersos, extensa de nanopartículas enlazadas faceta a faceta suele ser debido a dos razones: () la ODPA no se dispersan bien en la solución que contiene NR, que puede ser abordada por sonicando la mezcla para la pres...

La Asamblea dirigida del semiconductor coloidal NCs ofrece un camino sintético para la fabricación de nanoestructuras cuyas propiedades fisicoquímicas sean la suma colectiva de o radicalmente diferentes de sus individuales de bloques NC1 , 2 , 3 , 4. entre los diversos enfoques para ensamblaje de nanopartículas, el método de accesorio orientada - en que NCs son esencialmente fusionados entre sí - está parado hacia fuera como uno que permite el acoplamiento electrónico entre partículas. Sin embargo, convencional accesorio orientado típicamente requiere el delicado equilibrio de la partícula dipolo, ligando y las interacciones solvente-basó que son generalmente difíciles de ejecutar y hacer aplicable a diferentes sistemas de NC.
Recientemente hemos desarrollado un método de química húmeda de unirse covalentemente a cadmio forma anisotrópica calcógeno NCs introduciendo un intermedio reactivo inorgánico a través de un proceso de nucleación sitio selectivo. Posteriormente, las partículas están unidas por la fusión espontánea de los reactivos inorgánicos dominios intermedios5. Aunque la técnica aún se basa en un mecanismo orientado a conexión, hay mucho menos necesidad de considerar las interacciones entre partículas débiles, permitiendo más flexibilidad y control. La vinculación de cadmio forma anisotrópica calcógeno NCs se lleva a cabo primera convirtiendo sus facetas de punta a calcógeno plata mediante un proceso de intercambio catiónico parcial (en solución); Esto es seguido por la remoción selectiva de ligandos apaciguando la superficie. El NCs luego vienen juntos a través de la fusión de las facetas de chalcogenide plata expuestos, resultando en asambleas de cadmio calcógeno NCs ligadas end-to-end.
En este protocolo, se demuestra que la vinculación técnica puede aplicarse a una variedad de cadmio forma anisotrópica calcógeno NCs (es decir, semillas de CdSe CdS NRs y sembrado de CdSe CdSe NRs o TPs), que rinde lineares largas cadenas NR o TP muy ramificado redes. Estos resultados sugieren que la técnica puede extenderse a una amplia variedad de formas de NC y chalcogenides metálicos susceptibles de intercambio de catión plata.

<table width="724">
	<colgroup>
		<col />
		<col span="2" />
		<col />
	</colgroup>
	<tbody>
		<tr height="22">
			<td height="22" style="width:288px;height:22px;">Cadmium oxide (CdO), 99.5%</td>
			<td style="width:123px;">Sigma Aldrich</td>
			<td style="width:123px;"></td>
			<td style="width:191px;">Highly toxic</td>
		</tr>
		<tr height="43">
			<td height="43" style="width:288px;height:43px;">Tri-n-octylphosphine oxide (TOPO), 90 % and 99%</td>
			<td style="width:123px;">Sigma Aldrich</td>
			<td style="width:123px;"></td>
			<td style="width:191px;">Technical and analytical grade</td>
		</tr>
		<tr height="47">
			<td height="47" style="width:288px;height:47px;">Cadmium acetylacetonate (Cd(acac)2), 99.9%</td>
			<td style="width:123px;">Sigma Aldrich</td>
			<td style="width:123px;"></td>
			<td style="width:191px;">Highly toxic</td>
		</tr>
		<tr height="22">
			<td height="22" style="width:288px;height:22px;">Hexadecanediol (HDDO), 90%</td>
			<td style="width:123px;">Sigma Aldrich</td>
			<td style="width:123px;"></td>
			<td style="width:191px;">Technical grade</td>
		</tr>
		<tr height="22">
			<td height="22" style="width:288px;height:22px;">1-octadecene (ODE), 90%</td>
			<td style="width:123px;">Sigma Aldrich</td>
			<td style="width:123px;"></td>
			<td style="width:191px;">Technical grade</td>
		</tr>
		<tr height="22">
			<td height="22" style="width:288px;height:22px;">Dodecylamine (DDA), 98%</td>
			<td style="width:123px;">Sigma Aldrich</td>
			<td style="width:123px;"></td>
			<td style="width:191px;">Toxic</td>
		</tr>
		<tr height="47">
			<td height="47" style="width:288px;height:47px;">Cadmium nitrate tetrahydrate ((CdNO3)2.4H2O), 98%</td>
			<td style="width:123px;">Sigma Aldrich</td>
			<td style="width:123px;"></td>
			<td style="width:191px;">Highly toxic</td>
		</tr>
		<tr height="22">
			<td height="22" style="width:288px;height:22px;">Myristic acid (MA), 99%</td>
			<td style="width:123px;">Sigma Aldrich</td>
			<td style="width:123px;"></td>
			<td style="width:191px;">Analytical grade</td>
		</tr>
		<tr height="22">
			<td height="22" style="width:288px;height:22px;">Octyl phosphonic acid (OPA), 97%</td>
			<td style="width:123px;">Sigma Aldrich</td>
			<td style="width:123px;"></td>
			<td style="width:191px;">Analytical grade</td>
		</tr>
		<tr height="22">
			<td height="22" style="width:288px;height:22px;">Oleylamine (Oly), 70%</td>
			<td style="width:123px;">Sigma Aldrich</td>
			<td style="width:123px;"></td>
			<td style="width:191px;">Technical grade</td>
		</tr>
		<tr height="43">
			<td height="43" style="width:288px;height:43px;">Hexadecyltrimethylammonium bromide (CTAB), 95%</td>
			<td style="width:123px;">Sigma Aldrich</td>
			<td style="width:123px;"></td>
			<td style="width:191px;">Toxic</td>
		</tr>
		<tr height="22">
			<td height="22" style="width:288px;height:22px;">Selenium pellets (Se, 5 mm), 99.99%</td>
			<td style="width:123px;">Sigma Aldrich</td>
			<td style="width:123px;"></td>
			<td style="width:191px;">Analytical grade</td>
		</tr>
		<tr height="22">
			<td height="22" style="width:288px;height:22px;">Hexadecylamine (HDA), 90%</td>
			<td style="width:123px;">Alfa Aesar</td>
			<td style="width:123px;"></td>
			<td style="width:191px;">Technical grade, toxic</td>
		</tr>
		<tr height="22">
			<td height="22" style="width:288px;height:22px;">n-tetradecylphosphonic acid (TDPA), 98%&#160;</td>
			<td style="width:123px;">Alfa Aesar</td>
			<td style="width:123px;"></td>
			<td style="width:191px;">Analytical grade</td>
		</tr>
		<tr height="26">
			<td height="26" style="width:288px;height:26px;">Silver nitrate (AgNO3), 99.9%</td>
			<td style="width:123px;">Alfa Aesar</td>
			<td style="width:123px;"></td>
			<td style="width:191px;">Analytical grade</td>
		</tr>
		<tr height="22">
			<td height="22" style="width:288px;height:22px;">Oleic acid (OA), 90%</td>
			<td style="width:123px;">Alfa Aesar</td>
			<td style="width:123px;"></td>
			<td style="width:191px;">Technical grade</td>
		</tr>
		<tr height="43">
			<td height="43" style="width:288px;height:43px;">Tri-n-octylphosphine (TOP), 97%</td>
			<td style="width:123px;">Strem</td>
			<td style="width:123px;"></td>
			<td style="width:191px;">Analytical grade, toxic, air sensitive</td>
		</tr>
		<tr height="22">
			<td height="22" style="width:288px;height:22px;">n-hexylphosphonic acid (HPA), 97%</td>
			<td style="width:123px;">Strem</td>
			<td style="width:123px;"></td>
			<td style="width:191px;">Analytical grade</td>
		</tr>
		<tr height="22">
			<td height="22" style="width:288px;height:22px;">n-octadecylphosphonic acid (ODPA), 97%</td>
			<td style="width:123px;">Strem</td>
			<td style="width:123px;"></td>
			<td style="width:191px;">Analytical grade</td>
		</tr>
		<tr height="22">
			<td height="22" style="width:288px;height:22px;">Tellurium powder (Te), 99.9%</td>
			<td style="width:123px;">Strem</td>
			<td style="width:123px;"></td>
			<td style="width:191px;">Air sensitive</td>
		</tr>
		<tr height="43">
			<td height="43" style="width:288px;height:43px;">Tri-n-butylphosphine (TBP), 99%</td>
			<td style="width:123px;">Strem</td>
			<td style="width:123px;"></td>
			<td style="width:191px;">Analytical grade, highly toxic, air sensitive</td>
		</tr>
		<tr height="22">
			<td height="22" style="width:288px;height:22px;">Diisooctylphosphonic acid (DIPA), 90%</td>
			<td style="width:123px;">Fluka</td>
			<td style="width:123px;"></td>
			<td style="width:191px;">Technical grade, toxic</td>
		</tr>
	</tbody>
</table>

facet-to-facet linking of shape-anisotropic colloidal cadmium chalcogenide nanostructures

Aquí, describimos un protocolo que permite de forma anisotrópica cadmio calcógeno nanocristales (NCs), como nanobarras (NRs) y tetrápodos (TPs), covalente y site-specifically vinculados a través de sus aspectos finales, dando como resultado polímeros como lineal o ramificado cadenas. El procedimiento de enlace comienza con un proceso de intercambio catiónico en la que las facetas de la final del calcógeno cadmio NCs se convierten primero a calcógeno plata. Esto es seguido por la eliminación selectiva de los ligandos en la superficie. Esto resulta en cadmio calcógeno NCs con calcógeno plata altamente reactivo extremo facetas que espontáneamente al con con mutuamente, estableciendo un apego de faceta a faceta entre partículas. A través de la juiciosa elección de las concentraciones de precursores, se puede producir una extensa red de NCs vinculados. Caracterización estructural de las NCs vinculados se lleva a cabo a través de baja y alta resolución microscopia electrónica de transmisión (TEM), así como energía-dispersivo espectroscopia de rayos x, que confirman la presencia de dominios de chalcogenide plata entre cadenas de cadmio calcógeno NCs.

Usando semillas de CdSe CdS NRs como modelo, como se ilustra en la figura 1(a), hemos demostrado que podemos utilizar un proceso de intercambio de Ag+ parcial específicamente transformar las facetas en los consejos NR para Ag2S. Las facetas de2S Ag son capsuladas por DDA, que reacciona con ODPA mediante una reacción ácido-base para formar una sal insoluble5. Esto hace que los ligando...

Watch this Scientific Journal Video about Facet-to-facet Linking of Shape-anisotropic Colloidal Cadmium Chalcogenide Nanostructures at JoVE.com

Facet-to-facet Linking of Shape-anisotropic Colloidal Cadmium Chalcogenide Nanostructures

Un protocolo que detalla cómo forma anisotrópica cadmio coloidal calcógeno nanocristales pueden ser covalente a través de sus facetas de extremo se presenta aquí.

Faceta a faceta vincular de forma anisotrópica cadmio coloidal calcógeno nanoestructuras

Here, we describe a protocol that allows for shape-anisotropic cadmium chalcogenide nanocrystals (NCs), such as nanorods (NRs) and tetrapods (TPs), to be ...

facet-to-facet-linking-shape-anisotropic-colloidal-cadmium

Research

JoVE Journal

Chemistry

7.6K vistas.  National University of Singapore. Un protocolo que detalla cómo forma anisotrópica cadmio coloidal calcógeno nanocristales pueden ser covalente a través de sus facetas de extremo se presenta aquí.

Video: Facet-to-facet Linking of Shape-anisotropic Colloidal Cadmium Chalcogenide Nanostructures

Gyroid Nickel Nanostructures from Diblock Copolymer Supramolecules

Nanoporous metal foams possess a unique combination of properties - they are catalytically active, thermally and electrically conductive, and furthermore, have high porosity, high surface-to-volume and strength-to-weight ratio. Unfortunately, common approaches for preparation of metallic nanostructures render materials with highly disordered architecture, which might have an adverse effect on their mechanical properties. Block copolymers have the ability to self-assemble into ordered nanostructures and can be applied as templates for the preparation of well-ordered metal nanofoams. Here we describe the application of a block copolymer-based supramolecular complex - polystyrene-block-poly(4-vinylpyridine)(pentadecylphenol) PS-b-P4VP(PDP) - as a precursor for well-ordered nickel nanofoam. The supramolecular complexes exhibit a phase behavior similar to conventional block copolymers and can self-assemble into the bicontinuous gyroid morphology with two PS networks placed in a P4VP(PDP) matrix. PDP can be dissolved in ethanol leading to the formation of a porous structure that can be backfilled with metal. Using electroless plating technique, nickel can be inserted into the template&#39;s channels. Finally, the remaining polymer can be removed via pyrolysis from the polymer/inorganic nanohybrid resulting in nanoporous nickel foam with inverse gyroid morphology.

This article describes the preparation of well-ordered nickel nanofoams via electroless metal deposition onto nanoporous templates obtained from self-assembled diblock copolymer based supramolecules.

Gyroid Níquel Nanoestructuras de copolímero de dibloques supramoléculas

Nanoporous metal foams possess a unique combination of properties - they are catalytically active, thermally and electrically conductive, and furthermore, ...

Investigación

Química

Quantitative and Qualitative Examination of Particle-particle Interactions Using Colloidal Probe Nanoscopy

Colloidal Probe Nanoscopy (CPN), the study of the nano-scale interactive forces between a specifically prepared colloidal probe and any chosen substrate using the Atomic Force Microscope (AFM), can provide key insights into physical interactions present within colloidal systems. Colloidal systems are widely existent in several applications including, pharmaceuticals, foods, paints, paper, soil and minerals, detergents, printing and much more.1-3 Furthermore, colloids can exist in many states such as emulsions, foams and suspensions. Using colloidal probe nanoscopy one can obtain key information on the adhesive properties, binding energies and even gain insight into the physical stability and coagulation kinetics of the colloids present within. Additionally, colloidal probe nanoscopy can be used with biological cells to aid in drug discovery and formulation development. In this paper we describe a method for conducting colloidal probe nanoscopy, discuss key factors that are important to consider during the measurement, and show that both quantitative and qualitative data that can be obtained from such measurements.

Colloidal probe nanoscopy can be used within a variety of fields to gain insight into the physical stability and coagulation kinetics of colloidal systems and aid in drug discovery and formulation sciences using biological systems. The method described within provides a quantitative and qualitative means to study such systems.

El examen cuantitativo y cualitativo de las interacciones entre partículas Uso coloidal Sonda Nanoscopia

Colloidal Probe Nanoscopy (CPN), the study of the nano-scale interactive forces between a specifically prepared colloidal probe and any chosen substrate ...

Synthesis of Indoxyl-glycosides for Detection of Glycosidase Activities

Indoxyl glycosides proved to be valuable and versatile tools for monitoring glycosidase activities. Indoxyls are released by enzymatic hydrolysis and are rapidly oxidized, for example by atmospheric oxygen, to indigo type dyes. This reaction enables fast and easy screening in vivo without isolation or purification of enzymes, as well as rapid tests on agar plates or in solution (e.g., blue-white screening, micro-wells) and is used in biochemistry, histochemistry, bacteriology and molecular biology. Unfortunately the synthesis of such substrates proved to be difficult, due to various side reactions and the low reactivity of the indoxyl hydroxyl function. Especially for glucose type structures low yields were observed. Our novel approach employs indoxylic acid ester as key intermediates. Indoxylic acid esters with varied substitution patterns were prepared on scalable pathways. Phase transfer glycosylations with those acceptors and peracetylated glycosyl halides can be performed under common conditions in high yields. Ester cleavage and subsequent mild silver mediated glycosylation yields the peracetylated indoxyl glycosides in high yields. Finally deprotection is performed according to Zempl&#233;n.

Indoxyl glycosides are well-established and widely used tools for enzyme screening and enzyme activity monitoring. Especially for glucose type structures previous syntheses proved to be challenging and low yielding. Our novel approach employs indoxylic acid esters as precious intermediates to yield a considerable number of indoxyl glycosides in good yields.

Síntesis de indoxil-glucósidos para la detección de glucosidasa Actividades

Indoxyl glycosides proved to be valuable and versatile tools for monitoring glycosidase activities. Indoxyls are released by enzymatic hydrolysis and are ...

Synthesis and Exfoliation of Discotic Zirconium Phosphates to Obtain Colloidal Liquid Crystals

Due to their abundance in natural clay and potential applications in advanced materials, discotic nanoparticles are of interest to scientists and engineers. Growth of such anisotropic nanocrystals through a simple chemical method is a challenging task. In this study, we fabricate discotic nanodisks of zirconium phosphate [Zr(HPO4)2&#183;H2O] as a model material using hydrothermal, reflux and microwave-assisted methods. Growth of crystals is controlled by duration time, temperature, and concentration of reacting species. The novelty of the adopted methods is that discotic crystals of size ranging from hundred nanometers to few micrometers can be obtained while keeping the polydispersity well within control. The layered discotic crystals are converted to monolayers by exfoliation with tetra-(n)-butyl ammonium hydroxide [(C4H9)4NOH, TBAOH]. Exfoliated disks show isotropic and nematic liquid crystal phases. Size and polydispersity of disk suspensions is highly important in deciding their phase behavior.

A two dimensional model material of discotic zirconium phosphate was developed. The inorganic crystal with lamellar structure was synthesized by hydrothermal, reflux, and microwave-assisted methods. On exfoliation with organic molecules, layered crystals can be converted to monolayers, and nematic liquid crystal phase was formed at sufficient concentration of monolayers.

Síntesis y exfoliación de Discotic circonio fosfatos para obtener cristales líquidos coloidal

Due to their abundance in natural clay and potential applications in advanced materials, discotic nanoparticles are of interest to scientists and ...

Visualization of Ambient Mass Spectrometry with the Use of Schlieren Photography

This manuscript outlines how to visualize mass spectrometry ambient ionization sources using schlieren photography. In order to properly optimize the mass spectrometer, it is necessary to characterize and understand the physical principles of the source. Most commercial ambient ionization sources utilize jets of nitrogen, helium, or atmospheric air to facilitate the ionization of the analyte. As a consequence, schlieren photography can be used to visualize the gas streams by exploiting the differences in refractive index between the streams and ambient air for visualization in real time. The basic setup requires a camera, mirror, flashlight, and razor blade. When properly configured, a real time image of the source is observed by watching its reflection. This allows for insight into the mechanism of action in the source, and pathways to its optimization can be elucidated. Light is shed on an otherwise invisible situation.

This paper presents a protocol for the visualization of gaseous streams of an ambient ionization source using schlieren photography and mass spectrometry.

La visualización del ambiente Espectrometría de Masas con el uso de la fotografía Schlieren

This manuscript outlines how to visualize mass spectrometry ambient ionization sources using schlieren photography. In order to properly optimize the mass ...

Preparation and Characterization of C60/Graphene Hybrid Nanostructures

Physical thermal deposition in a high vacuum environment is a clean and controllable method for fabricating novel molecular nanostructures on graphene. We present methods for depositing and passively manipulating C60 molecules on rippled graphene that advance the pursuit of realizing applications involving 1D C60/graphene hybrid structures. The techniques applied in this exposition are geared towards high vacuum systems with preparation areas capable of supporting molecular deposition as well as thermal annealing of the samples. We focus on C60 deposition at low pressure using a homemade Knudsen cell connected to a scanning tunneling microscopy (STM) system. The number of molecules deposited is regulated by controlling the temperature of the Knudsen cell and the deposition time. One-dimensional (1D) C60 chain structures with widths of two to three molecules can be prepared via tuning of the experimental conditions. The surface mobility of the C60 molecules increases with annealing temperature allowing them to move within the periodic potential of the rippled graphene. Using this mechanism, it is possible to control the transition of 1D C60 chain structures to a hexagonal close packed quasi-1D stripe structure.

Preparation and Characterization of C60/Graphene Hybrid Nanostructures

Here we present a protocol for the fabrication of C60/graphene hybrid nanostructures by physical thermal evaporation. Particularly, the proper manipulation of deposition and annealing conditions allow the control over the creation of 1D and quasi 1D C60 structures on rippled graphene.

Preparación y caracterización de nanoestructuras de C60/Graphene híbrido

Physical thermal deposition in a high vacuum environment is a clean and controllable method for fabricating novel molecular nanostructures on graphene. We ...

The Effect of Ultraviolet Radiation on the Chemical Bath Deposition of Bis(thiourea) Cadmium Chloride Crystals and the Subsequent CdS Obtention

In this work, the effects on the preparation of bis(thiourea) cadmium chloride crystals when illuminated with ultraviolet (UV) light at a wavelength of 367 nm using the chemical bath deposition technique are studied comparatively. Two experiments are performed to make a comparison: one without UV light and the other with the aid of UV light. Both experiments are performed under equal conditions, at a temperature of 343 K and with a pH of 3.2. The precursors used are cadmium chloride (CdCl2) and thiourea [CS(NH2)2], which are dissolved in 50 mL of deionized water with an acidic pH. In this experiment, the interaction of electromagnetic radiation is sought at the moment the chemical reaction is carried out. The results demonstrate the existence of an interaction between the crystals and the UV light; the UV light assistance causes crystal growths in an acicular shape. Also, the final product obtained is cadmium sulfide and shows no evident difference when synthesized with or without the use of UV light.

The Effect of Ultraviolet Radiation on the Chemical Bath Deposition of Bisthiourea Cadmium Chloride Crystals and the Subsequent CdS Obtention

This article presents a protocol for the synthesis of bis(thiourea) cadmium chloride crystals by chemical bath deposition. Two experiments are described: one aided by ultraviolet light compared to one without ultraviolet light.

El efecto de la radiación ultravioleta en la deposición química del baño de Bis(thiourea) cadmio cloruro cristales y la posterior obtención de CdS

In this work, the effects on the preparation of bis(thiourea) cadmium chloride crystals when illuminated with ultraviolet (UV) light at a wavelength of ...

Photoelectron Imaging of Anions Illustrated by 310 Nm Detachment of F&#8722;

Anion photoelectron imaging is a very efficient method for the study of energy states of bound negative ions, neutral species and interactions of unbound electrons with neutral molecules/atoms. State-of-the-art in vacuo anion generation techniques allow application to a broad range of atomic, molecular, and cluster anion systems. These are separated and selected using time-of-flight mass spectrometry. Electrons are removed by linearly polarized photons (photo detachment) using table-top laser sources which provide ready access to excitation energies from the infra-red to the near ultraviolet. Detecting the photoelectrons with a velocity mapped imaging lens and position sensitive detector means that, in principle, every photoelectron reaches the detector and the detection efficiency is uniform for all kinetic energies. Photoelectron spectra extracted from the images via mathematical reconstruction using an inverse Abel transformation reveal details of the anion internal energy state distribution and the resultant neutral energy states. At low electron kinetic energy, typical resolution is sufficient to reveal energy level differences on the order of a few millielectron-volts, i.e., different vibrational levels for molecular species or spin-orbit splitting in atoms. Photoelectron angular distributions extracted from the inverse Abel transformation represent the signatures of the bound electron orbital, allowing more detailed probing of electronic structure. The spectra and angular distributions also encode details of the interactions between the outgoing electron and the residual neutral species subsequent to excitation. The technique is illustrated by the application to an atomic anion (F&#8722;), but it can also be applied to the measurement of molecular anion spectroscopy, the study of low lying anion resonances (as an alternative to scattering experiments) and femtosecond (fs) time resolved studies of the dynamic evolution of anions.

Here, we present a protocol for photoelectron imaging of anionic species. Anions generated in vacuo and separated by mass spectrometry are probed using velocity mapped photoelectron imaging, providing details of anion and neutral energy levels, anion and neutral structure and the nature of the anion electronic state.

La proyección de imagen del fotoelectrón de aniones ilustrado por 310 Nm la separación de F−

Anion photoelectron imaging is a very efficient method for the study of energy states of bound negative ions, neutral species and interactions of unbound ...

Stable DNA Motifs, 1D and 2D Nanostructures Constructed from Small Circular DNA Molecules

This article presents a detailed protocol for synthesis of small circular DNA molecules, annealing of circular DNA motifs, and construction of 1D and 2D DNA nanostructures. Over decades, the rapid development of DNA nanotechnology is attributed to the use of linear DNAs as the source materials. For example, the DAO (double crossover, antiparallel, odd half-turns) tile is well-known as a building block for construction of 2D DNA lattices; the core structure of DAO is made from two linear single-stranded (ss) oligonucleotides, like two ropes making a right hand granny&#160;knot. Herein, a new type of DNA tiles called cDAO (coupled DAO) are built using a small circular ss-DNA of c64nt or c84nt (circular 64 or 84 nucleotides) as the scaffold strand and several linear ss-DNAs as the staple strands. Perfect 1D and 2D nanostructures are assembled from cDAO tiles: infinite nanowires, nanospirals, nanotubes, nanoribbons; and finite nano-rectangles. Detailed protocols are described: 1) preparation by T4 ligase and purification by denaturing PAGE (polyacrylamide gel electrophoresis) of small circular oligonucleotides, 2) annealing of stable circular tiles, followed by native PAGE analysis, 3) assembling of infinite 1D nanowires, nanorings, nanospirals, infinite 2D lattices of nanotubes and nanoribbons, and finite 2D nano-rectangles, followed by AFM (Atomic Force Microscopy) imaging. The method is simple, robust, and affordable for most labs.

This article presents a detailed protocol for T4 ligation and denaturing PAGE purification of small circular DNA molecules, annealing and native PAGE analysis of circular tiles, assembling and AFM imaging of 1D and 2D DNA nanostructures, as well as agarose gel electrophoresis and centrifugation purification of finite DNA nanostructures.

Motivos de ADN estable, 1D y 2D nanoestructuras construyen a partir de moléculas de ADN Circular pequeño

This article presents a detailed protocol for synthesis of small circular DNA molecules, annealing of circular DNA motifs, and construction of 1D and 2D ...

Gene-therapy Inspired Polycation Coating for Protection of DNA Origami Nanostructures

DNA origami nanostructures hold an immense potential to be used for biological and medical applications. However, low-salt conditions and nucleases in physiological fluids induce denaturation and degradation of self-assembled DNA nanostructures. In non-viral gene delivery, enzymatic degradation of DNA is overcome by the encapsulation of the negatively charged DNA in a cationic shell. Herein, inspired by gene delivery advancements, a simple, one-step and robust methodology is presented for the stabilization of DNA origami nanostructures by coating them with chitosan and linear polyethyleneimine. The polycation coating efficiently protects DNA origami nanostructures in Mg-depleted and nuclease-rich media. This method also preserves the full addressability of enzyme- and aptamer-based functionalization of DNA nanostructures.

Here, a protocol for the protection of DNA origami nanostructures in Mg-depleted and nuclease-rich media using natural cationic polysaccharide chitosan and synthetic linear polyethyleneimine (LPEI) coatings is presented.

Terapia génica inspirado POLICATIÓN recubrimiento para protección de nanoestructuras de Origami de ADN

DNA origami nanostructures hold an immense potential to be used for biological and medical applications. However, low-salt conditions and nucleases in ...