Os autores agradecem Svilen Bobev por sua ajuda com os espectros de DRX e K. Booksh de assistência com o equipamento de pulverização catódica coater.

1. Síntese de árvore-como ZnO / CdSSe Nanoestruturas <ol><li> O pré-tratamento e ouro revestimento de substratos de safira NOTA: O filme de ouro actua como um catalisador no crescimento dos nanofios de ZnO. <ol><li> lâminas de safira limpa (a-avião, 10 × 10 × 1 mm) em 99,5% de etanol com 5 min de sonicação para preparar o substrato para Au pulverização catódica. </li><li> Depositar a 10 nm (± 2 nm) filme -grossa de ouro nas lâminas de safira com um revestidor por crepitação e alvo de ouro. </li></ol></li><li> Síntese de nanofios de ZnO NOTA: O passo de sonicação 1.2.2 resulta em uma ZnO homogênea e carbono (/ C ZnO) mistura. Após a mistura, a mistura muda para uma cor cinza. A etapa de compactação 1.2.3 garante que nenhum ar está presente na mistura e que o ZnO e carbono estão em contato próximo. Depois de DCV, uma película branca de nanofios de ZnO deve ser depositado sobre o substrato, lado voltado para baixo para o barco. <ol><li> Misture 1 g de nanopowder ZnO e activated carbono (fracção de massa de 50:50) em 10 ml de etanol a 99,5% e agita-se bem com uma espátula. </li><li> Sonicar a mistura num banho de água a 20 ºC durante 30 min, e em seguida secá-lo numa estufa durante ~ 5 horas a 80 ºC. </li><li> Coloque a mistura de ZnO / C numa barquinha de alumina e compacta-lo bem com uma espátula. </li><li> Colocar as lâminas de safira revestido a ouro no topo da barquinha de alumina, com o lado revestido a ouro voltado para baixo. Coloque a barquinha de alumina no centro do tubo de quartzo num forno tubular horizontal. </li><li> Purga-se o tubo de quartzo, durante 1 h com atmosfera de Ar a uma taxa de fluxo de 40 sccm à temperatura ambiente (RT). Aumentar a temperatura de RT a 900 ° C a uma taxa de 80 ° C / min e manter constante a taxa de fluxo de árgon. </li><li> Mantenha a temperatura a 900 ° C durante 2 horas. Abrir o tubo de quartzo em ambas as extremidades, removendo as entradas de gás e de rolha de borracha que o ar entre o tubo para fornecer oxigénio para a reacção. </li><li> Manter a temperatura da reacção a 900 ° C durante 3 h com o RUrolhas bber removido. Arrefecer até à TA, a uma taxa de 10 ° C / min. </li><li> Pegue o barco e deslizar para fora do forno. </li></ol></li><li> Deposição de ramos CdSSe em nanofios de ZnO NOTA: O barco de alumina do CDS / Se foi apresentada no centro do tubo de quartzo. Os nanofios de ZnO foram preparadas virada para cima, e foram de 10 cm a jusante a partir do barco. Após esta segunda DCV, uma laranja / filme amarelo, que é a nanoestrutura ZnO / CdSSe, deve ser depositada sobre a lâmina. <ol><li> Misture 0,5 g de CDs e CdSe (CDS / Se) bem pó (fração de massa de 50:50) e coloque a mistura em um barco de alumina. Compactar bem a mistura. </li><li> Coloque o barco alumina do CDS / SE e da amostra de ZnO nanofio previamente preparado no tubo de quartzo. </li><li> Purga-se o tubo com atmosfera de Ar a uma taxa de fluxo de 40 sccm à TA durante 1 h. Aumentar a temperatura de reacção para 820 ° C a uma taxa de 80 ° C / min. Mantenha a temperatura a 820 ° C durante 30 min. </li><li> Arrefecer até à RT emuma taxa de 10 ° C / min. Pegue o barco e deslizar para fora do forno. </li></ol></li><li> Síntese das amostras de controlo: ZnO e CdSSe nanofios <ol><li> Sintetizar nanofios de ZnO como na secção 1.2, sob as mesmas condições experimentais. </li><li> Sintetizar nanofios CdSSe como no ponto 1.3, sob as mesmas condições experimentais, com a mesma quantidade de CDs e composição CdSe, mas com, um slide de safira revestido a ouro limpo como substrato em vez do slide depositados-ZnO. </li></ol></li></ol> 2. morfológica e cristalográfica Caracterização <ol><li> Montar a amostra na fase SEM com uma braçadeira e colocar a amostra na câmara de vácuo do instrumento SEM. Tome imagens de MEV no modo de alta resolução com uma distância de trabalho de 12,0 mm a uma tensão de 3 kV e uma ampliação entre 3,000X e 10.000 vezes 11,12. </li><li> Tome dados de EDS com a mesma amostra usando o detector de raios-X à mesma distância de trabalho de12.0 mm. Ajustar o instrumento para o modo de análise e ajustar a tensão de 20 kV, resultando em uma corrente de 20 a 40 uA 13. </li><li> Recolhe espectros de DRX, em um difractómetro de pó por raios-X usando radiação Cu Ka filtrada (λ = 1,5418 Â) 11,12. </li></ol> 3. PL Espectroscopia de Emissão e Medidas Lifetime PL resolvida no tempo Observação: Os espectros de PL e contagem de fotão único correlacionados em tempo (TCSPC) medições a RT foram realizadas utilizando um amplificado Ti: oscilador safira após a segunda geração de harmónica (SHG), a produção de um trem de 50 impulsos FSEC centrado no comprimento de onda de 400 nm e com uma potência de saída de 1,76 mW 14. <ol><li> Fixar a amostra num suporte de amostras que posiciona a face da amostra até o laser e o detector. Alinhar o laser para focar a amostra. Medir o espectro de emissão PL das amostras a partir de 500 nm, comprimentos de onda de 900 nm utilizando um espectrómetro de fibra. </li><li> Use um detector de fóton único (avalanche foto diodo ou phototube) para medir vidas PL resolvidas no tempo com um filtro de vidro de cor e um filtro de interferência de banda de 500 ou 650 nm. </li><li> Inserir ZnO, CdSSe ou ZnO / CdSSe desliza no suporte da amostra. Meça os nanofios de ZnO puros com o filtro de banda de 500 nm e as amostras CdSSe ou ZnO / CdSSe com um filtro de banda de 650 nm. </li><li> Usar um contador de fóton único correlacionados em tempo ou um osciloscópio rápido para medir o tempo de vida de fluorescência de decaimento resolvidas no tempo. </li></ol>

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Dados e números neste artigo são citados na literatura em nanotecnologia por Li et al. 17.

O alinhamento vertical das nanofios de ZnO (hastes) baseia-se no crescimento epitaxial sobre o substrato. Nanofios de ZnO crescer preferencialmente ao longo da &lt;0001&gt; direção que combina com a periodicidade de um plano de safira 12. Portanto, o tipo e a qualidade do substrato são muito importantes. Diferentes espessuras do revestimento de ouro no substrato, a partir de 5 nm a 20 nm, foram testados e mostraram nenhuma diferença significativa no crescimento de nanofios de ZnO. O comprimento dos nanofi...

ZnO é um semicondutor II-VI com um gap (BG) de 3,3 eV, uma alta mobilidade de elétrons e um 1,2 energia de ligação grande éxciton. É um material semicondutor abundante com uma infinidade de aplicações presentes e futuras em dispositivos ópticos, células solares, e fotocatálise. No entanto, ZnO é transparente, o que limita a sua aplicação na gama espectral visível. Portanto, materiais absorventes de luz visível, tais como semicondutores narrow-gap 3, moléculas de corante 4, e polímeros fotossensíveis 5, têm sido frequentemente utilizados para sensibilizar ZnO a absorção de luz visível. CDs (BG 2,43 eV) e CdSe (BG 1,76 eV) são comuns II-VI semicondutores narrow-gap e têm sido intensamente investigados. Os parâmetros de BG e gelosia da liga ternária CdSSe pode ser ajustado através da variação das razões molares dos componentes VI 6,7. nanocompósitos ZnO / CdSSe ter sido relatada como resultando em photov eficienteconversão de energia oltaic 8,9. Combinando a via de transporte de elétrons eficiente de nanofios de ZnO alinhados verticalmente contra um substrato com a absorção de luz visível melhoria dos ramos CdSSe levou à transferência de elétrons eficiente entre o caule e ramos 9,10. Assim, sintetizamos uma nova árvore-como ZnO / CdSSe nanoestrutura, onde nanofios de ZnO alinhados verticalmente são decorados com ramos CdSSe. Este material compósito pode actuar como um bloco de construção de novos dispositivos de conversão de energia solar. Este protocolo descreve como matrizes de nanofios de ZnO são cultivados num substrato de safira por deposição de vapor químico de um passo (DCV) a partir de pós de ZnO e C, seguindo um procedimento que foi anteriormente publicado a 11. Seguindo o crescimento de nanofios de ZnO, um segundo passo de DCV é empregue para crescer em ramos CdSSe os nanofios de ZnO. Empregamos de difracção de raios-X em pó (XRD), microscopia electrónica de varrimento (SEM), eespectroscopia de raios-X de energia dispersiva (EDS) para medir a estruturas de cristal, morfologia e composição das nanotrees ZnO / CdSSe (NTs). O mecanismo de transferência de propriedades ópticas e carga transportadora entre os ramos e caule foram investigados por fotoluminescência (PL) espectroscopia e as medições ao longo da vida PL resolvidas no tempo.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>ZnO</td>
			<td>Sigma Aldrich</td>
			<td>1314-13-2</td>
			<td></td>
		</tr>
		<tr>
			<td>Activated Carbon</td>
			<td>Alfa</td>
			<td>231-153-3</td>
			<td></td>
		</tr>
		<tr>
			<td>CdSe</td>
			<td>Sigma Aldrich</td>
			<td>1306-24-7</td>
			<td></td>
		</tr>
		<tr>
			<td>CdS</td>
			<td>Sigma Aldrich</td>
			<td>1306-23-6</td>
			<td></td>
		</tr>
		<tr>
			<td>Sapphire</td>
			<td>MTI</td>
			<td>2SP</td>
			<td>a-plane, 10 &#215; 10 &#215; 1 mm</td>
		</tr>
		<tr>
			<td>Furnace</td>
			<td>Lindberg Blue M</td>
			<td>SSP</td>
			<td></td>
		</tr>
		<tr>
			<td>Scanning electron microscope</td>
			<td>Hitachi</td>
			<td>S5700</td>
			<td>assembled with an Oxford Inca X-act detector</td>
		</tr>
		<tr>
			<td>X-ray powder diffractometer&#160;</td>
			<td>Rigaku&#160;</td>
			<td>MiniFlex</td>
			<td>filtered Cu K&#945; radiation (&#955;=1.5418 &#197;)</td>
		</tr>
		<tr>
			<td>Amplified Ti:sapphire oscillator&#160;</td>
			<td>Coherent Mantis</td>
			<td>Coherent Legend-Elite</td>
			<td></td>
		</tr>
		<tr>
			<td>Single photon detection module&#160;</td>
			<td>ID Quantique</td>
			<td>ID-100</td>
			<td></td>
		</tr>
		<tr>
			<td>Sputter coater</td>
			<td>Cressington</td>
			<td>308</td>
			<td>assembled with gold target</td>
		</tr>
		<tr>
			<td>Fiber probe spectrometer</td>
			<td>Photon Control</td>
			<td>SPM-002</td>
			<td></td>
		</tr>
		<tr>
			<td>Colored Glass Filter</td>
			<td>Thorlabs</td>
			<td>FGB37-A - &#216;25 mm BG40</td>
			<td>AR Coated: 350 - 700 nm&#160;</td>
		</tr>
		<tr>
			<td>Compressed argon gas</td>
			<td>Keen</td>
			<td>7440-37-1</td>
			<td></td>
		</tr>
	</tbody>
</table>

synthesis of hierarchical zno/cdsse heterostructure nanotrees

Um procedimento de deposição de vapor químico de duas etapas é aqui empregue para preparar hierárquicos ZnO / CdSSe hetero-nanoestruturas de árvore. As estruturas são compostas por ramos CdSSe cultivadas em nanofios de ZnO que estão verticalmente alinhados sobre um substrato de safira transparente. A morfologia foi medida através de microscopia eletrônica de varredura. A estrutura cristalina foi determinada por análise de difracção de pó de raios-X. Tanto o ZnO caule e ramos CdSSe tem uma estrutura de cristal predominantemente wurtzita. A proporção molar de S e Se, nos ramos CdSSe foi medido por espectroscopia de raios X de energia dispersiva. Os ramos CdSSe resultar em forte absorção de luz visível. Fotoluminescência (PL) espectroscopia mostraram que o caule e dos ramos formam um heterojunï¿½o tipo II. medições vida PL mostraram uma diminuição no tempo de vida de emissão das árvores, quando em comparação com a emissão de ZnO hastes individuais ou ramos CdSSe e indicar rápida transferência de carga entre CdSSe e ZnO. o verticamente alinhados ZnO hastes proporcionar uma via de transporte de electrões directamente para o substrato e para permitir a separação de carga eficiente após fotoexcitação pela luz visível. A combinação das propriedades acima mencionadas faz ZnO / CdSSe nanotrees candidatos promissores para aplicações em células solares, fotocatálise, e dispositivos opto-electrónicos.

A Figura 1 mostra o mecanismo de crescimento de ZnO / NTs CdSSe. O procedimento envolveu um processo catalítico de vapor-líquido-sólido (VLS), seguido por um crescimento de vapor-sólido não catalítico (VS). No primeiro passo VLS, ZnO e C reagem na atmosfera de Ar, resultando em Zn metálico e óxido de carbono. Zn é subsequentemente dissolvido no precursor de ouro no substrato de safira. nanofios de ZnO crescer a partir do Zn dissolvido e oxigênio residual. No se...

Watch this Scientific Journal Video about Synthesis of Hierarchical ZnO/CdSSe Heterostructure Nanotrees at JoVE.com

Synthesis of Hierarchical ZnO/CdSSe Heterostructure Nanotrees

Aqui, nós preparar e caracterizar novos hierárquicos nanoestruturas de ZnO / CdSSe árvore-like, onde ramos CdSSe são cultivadas em nanofios de ZnO alinhados verticalmente. Os nanotrees resultantes são um material potencial para a conversão de energia solar e outros dispositivos opto-electrónicos.

Síntese de hierárquicos ZnO / CdSSe heterostructure Nanotrees

A two-step chemical vapor deposition procedure is here employed to prepare tree-like hierarchical ZnO/CdSSe hetero-nanostructures. The structures are ...

synthesis-of-hierarchical-znocdsse-heterostructure-nanotrees

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Chemistry

9.9K visualizações.  University of Delaware.  Aqui, nós preparar e caracterizar novos hierárquicos nanoestruturas de ZnO / CdSSe árvore-like, onde ramos CdSSe são cultivadas em nanofios de ZnO alinhados verticalmente. Os nanotrees resultantes são um material potencial para a conversão de energia solar e outros dispositivos opto-electrónicos. 

Vídeo: Synthesis of Hierarchical ZnO/CdSSe Heterostructure Nanotrees

Synthesis of Immunotargeted Magneto-plasmonic Nanoclusters

Magnetic and plasmonic properties combined in a single nanoparticle provide a synergy that is advantageous in a number of biomedical applications including contrast enhancement in novel magnetomotive imaging modalities, simultaneous capture&#160;and detection of circulating tumor cells (CTCs),&#160;and multimodal molecular imaging combined with photothermal therapy of cancer cells. These applications have stimulated significant interest in development of protocols for synthesis of magneto-plasmonic nanoparticles with optical absorbance in the near-infrared (NIR) region and a strong magnetic moment. Here, we present a novel protocol for synthesis of such hybrid nanoparticles that is based on an oil-in-water microemulsion method. The unique feature of the protocol described herein is synthesis of magneto-plasmonic nanoparticles of various sizes from primary blocks which also have magneto-plasmonic characteristics. This approach yields nanoparticles with a high density of magnetic and plasmonic functionalities which are uniformly distributed throughout the nanoparticle volume. The hybrid nanoparticles can be easily functionalized by attaching antibodies through the Fc moiety leaving the Fab portion that is responsible for antigen binding available for targeting.

Here, we describe a protocol for synthesis of magneto-plasmonic nanoparticles with a strong magnetic moment and a strong near-infrared (NIR) absorbance. The protocol also includes antibody conjugation to the nanoparticles through the Fc moiety for various biomedical applications which require molecular specific targeting.

Síntese de Immunotargeted magneto-plasmónico Nanoclusters

Magnetic and plasmonic properties combined in a single nanoparticle provide a synergy that is advantageous in a number of biomedical applications ...

Química

Synthesis and Characterization of Functionalized Metal-organic Frameworks

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

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

Síntese e caracterização de funcionalizados metal-organic frameworks

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

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.

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

Synthesis and Characterization of Supramolecular Colloids

Control over colloidal assembly is of utmost importance for the development of functional colloidal materials with tailored structural and mechanical properties for applications in photonics, drug delivery and coating technology. Here we present a new family of colloidal building blocks, coined supramolecular colloids, whose self-assembly is controlled through surface-functionalization with a benzene-1,3,5-tricarboxamide (BTA) derived supramolecular moiety. Such BTAs interact via directional, strong, yet reversible hydrogen-bonds with other identical BTAs. Herein, a protocol is presented that describes how to couple these BTAs to colloids and how to quantify the number of coupling sites, which determines the multivalency of the supramolecular colloids. Light scattering measurements show that the refractive index of the colloids is almost matched with that of the solvent, which strongly reduces the van der Waals forces between the colloids. Before photo-activation, the colloids remain well dispersed, as the BTAs are equipped with a photo-labile group that blocks the formation of hydrogen-bonds. Controlled deprotection with UV-light activates the short-range hydrogen-bonds between the BTAs, which triggers the colloidal self-assembly. The evolution from the dispersed state to the clustered state is monitored by confocal microscopy. These results are further quantified by image analysis with simple routines using ImageJ and Matlab. This merger of supramolecular chemistry and colloidal science offers a direct route towards light- and thermo-responsive colloidal assembly encoded in the surface-grafted monolayer.

A protocol for the synthesis and characterization of colloids coated with supramolecular moieties is described. These supramolecular colloids undergo self-assembly upon the activation of the hydrogen-bonds between the surface-anchored molecules by UV-light.

Síntese e Caracterização de Supramoleculares Colloids

Control over colloidal assembly is of utmost importance for the development of functional colloidal materials with tailored structural and mechanical ...

Hydroquinone Based Synthesis of Gold Nanorods

Gold nanorods are an important kind of nanoparticles characterized by peculiar plasmonic properties. Despite their widespread use in nanotechnology, the synthetic methods for the preparation of gold nanorods are still not fully optimized. In this paper we describe a new, highly efficient, two-step protocol based on the use of hydroquinone as a mild reducing agent. Our approach allows the preparation of nanorods with a good control of size and aspect ratio (AR) simply by varying the amount of hexadecyl trimethylammonium bromide (CTAB) and silver ions (Ag+) present in the "growth solution". By using this method, it is possible to markedly reduce the amount of CTAB, an expensive and cytotoxic reagent, necessary to obtain the elongated shape. Gold nanorods with an aspect ratio of about 3 can be obtained in the presence of just 50 mM of CTAB (versus 100 mM used in the standard protocol based on the use of ascorbic acid), while shorter gold nanorods are obtained using a concentration as low as 10 mM.

This paper describes a protocol for the synthesis of gold nanorods, based on the use of hydroquinone as reducing agent, plus the different mechanisms for controlling their size and aspect ratio.

Hidroquinona baseada Síntese de ouro Nanorods

Gold nanorods are an important kind of nanoparticles characterized by peculiar plasmonic properties. Despite their widespread use in nanotechnology, the ...

Synthesis and Mass Spectrometry Analysis of Oligo-peptoids

Peptoids are sequence-controlled peptide-mimicking oligomers consisting of N-alkylated glycine units. Among many potential applications, peptoids have been thought of as a type of molecular information storage. Mass spectrometry analysis has been considered the method of choice for sequencing peptoids. Peptoids can be synthesized via solid phase chemistry using a repeating two-step reaction cycle. Here we present a method to manually synthesize oligo-peptoids and to analyze the sequence of the peptoids using tandem mass spectrometry (MS/MS) techniques. The sample peptoid is a nonamer consisting of alternating N-(2-methyloxyethyl)glycine (Nme) and N-(2-phenylethyl)glycine (Npe), as well as an N-(2-aminoethyl)glycine (Nae) at the N-terminus. The sequence formula of the peptoid is Ac-Nae-(Npe-Nme)4-NH2, where Ac is the acetyl group. The synthesis takes place in a commercially available solid-phase reaction vessel. The rink amide resin is used as the solid support to yield the peptoid with an amide group at the C-terminus. The resulting peptoid product is subjected to sequence analysis using a triple-quadrupole mass spectrometer coupled to an electrospray ionization source. The MS/MS measurement produces a spectrum of fragment ions resulting from the dissociation of charged peptoid. The fragment ions are sorted out based on the values of their mass-to-charge ratio (m/z). The m/z values of the fragment ions are compared against the nominal masses of theoretically predicted fragment ions, according to the scheme of peptoid fragmentation. The analysis generates a fragmentation pattern of the charged peptoid. The fragmentation pattern is correlated to the monomer sequence of the neutral peptoid. In this regard, MS analysis reads out the sequence information of the peptoids.

A protocol is described for the manual synthesis of oligo-peptoids followed by sequence analysis by mass spectrometry.

Síntese e análise de espectrometria de massa de Oligo-peptoids

Peptoids are sequence-controlled peptide-mimicking oligomers consisting of N-alkylated glycine units. Among many potential applications, peptoids have ...

Synthesis of Substrate-Bound Au Nanowires Via an Active Surface Growth Mechanism

Advancing synthetic capabilities is important for the development of nanoscience and nanotechnology. The synthesis of nanowires has always been a challenge, as it requires asymmetric growth of symmetric crystals. Here, we report a distinctive synthesis of substrate-bound Au nanowires. This template-free synthesis employs thiolated ligands and substrate adsorption to achieve the continuous asymmetric deposition of Au in solution at ambient conditions. The thiolated ligand prevented the Au deposition on the exposed surface of the seeds, so the Au deposition only occurs at the interface between the Au seeds and the substrate. The side of the newly deposited Au nanowires is immediately covered with the thiolated ligand, while the bottom facing the substrate remains ligand-free and active for the next round of Au deposition. We further demonstrate that this Au nanowire growth can be induced on various substrates, and different thiolated ligands can be used to regulate the surface chemistry of the nanowires. The diameter of the nanowires can also be controlled with mixed ligands, in which another &#34;bad&#34; ligand could turn on the lateral growth. With the understanding of the mechanism, Au nanowire-based nanostructures can be designed and synthesized.

We report a solution-based method to synthesize substrate-bound Au nanowires. By tuning the molecular ligands used during the synthesis, the Au nanowires can be grown from various substrates with different surface properties. Au nanowire-based nanostructures can also be synthesized by adjusting the reaction parameters.

Síntese de nanofios de Au substrato ligados através de um mecanismo de crescimento ativo de superfície

Advancing synthetic capabilities is important for the development of nanoscience and nanotechnology. The synthesis of nanowires has always been a ...

Solid-phase Synthesis of [4.4] Spirocyclic Oximes

A convenient synthetic route for spirocyclic heterocycles is well sought after due to the molecule&#39;s potential use in biological systems. By means of solid-phase synthesis, regenerating Michael (REM) linker strategies, and 1,3-dipolar cycloaddition, a library of structurally similar heterocycles, both with and without a spirocyclic center, can be constructed. The main advantages of the solid-support synthesis are as follows: first, each reaction step can be driven to completion using a large excess of reagents resulting in high yields; next, the use of commercially available starting materials and reagents keep the costs low; finally, the reaction steps are easy to purify via simple filtration. The REM linker strategy is attractive because of its recyclability and traceless nature. Once a reaction scheme is completed, the linker can be reused multiple times. In a typical solid-phase synthesis, the product contains either a part of or the whole linker, which can prove undesirable. The REM linker is &#34;traceless&#34; and the point of attachment between the product and the polymer is indistinguishable. The high diastereoselectivity of the intramolecular 1,3-dipolar cycloaddition is well documented. Limited by the insolubility of the solid support, the reaction progression can only be monitored by a change in the functional groups (if any) via infrared (IR) spectroscopy. Thus, the structural identification of intermediates cannot be characterized by conventional nuclear magnetic resonance (NMR) spectroscopy. Other limitations to this method stem from the compatibilities of the polymer/linker to the desired chemical reaction scheme. Herein we report a protocol that allows for the convenient production of spirocyclic heterocycles that, with simple modifications, can be automated with high-throughput techniques.

Here we present a protocol to demonstrate an efficient method for the synthesis of spirocyclic heterocycles. The five-step process utilizes solid-phase synthesis and regenerating Michael linker strategies. Generally difficult to synthesize, we present a customizable method for the synthesis of spirocyclic molecules otherwise inaccessible to other modern approaches.

Fase sólida síntese de [4,4] Spirocyclic oximas

A convenient synthetic route for spirocyclic heterocycles is well sought after due to the molecule&#39;s potential use in biological systems. By means of ...

Synthesis and Characterization of Amphiphilic Gold Nanoparticles

Gold nanoparticles covered with a mixture of 1-octanethiol (OT) and 11-mercapto-1-undecane sulfonic acid (MUS) have been extensively studied because of their interactions with cell membranes, lipid bilayers, and viruses. The hydrophilic ligands make these particles colloidally stable in aqueous solutions and the combination with hydrophobic ligands creates an amphiphilic particle that can be loaded with hydrophobic drugs, fuse with the lipid membranes, and resist nonspecific protein adsorption. Many of these properties depend on nanoparticle size and the composition of the ligand shell. It is, therefore, crucial to have a reproducible synthetic method and reliable characterization techniques that allow the determination of nanoparticle properties and the ligand shell composition. Here, a one-phase chemical reduction, followed by a thorough purification to synthesize these nanoparticles with diameters below 5 nm, is presented. The ratio between the two ligands on the surface of the nanoparticle can be tuned through their stoichiometric ratio used during synthesis. We demonstrate how various routine techniques, such as transmission electron microscopy (TEM), nuclear magnetic resonance (NMR), thermogravimetric analysis (TGA), and ultraviolet-visible (UV-Vis) spectrometry, are combined to comprehensively characterize the physicochemical parameters of the nanoparticles.

Amphiphilic gold nanoparticles can be used in many biological applications. A protocol to synthesize gold nanoparticles coated by a binary mixture of ligands and a detailed characterization of these particles is presented.

Síntese e caracterização de nanopartículas de ouro Anfífilos

Gold nanoparticles covered with a mixture of 1-octanethiol (OT) and 11-mercapto-1-undecane sulfonic acid (MUS) have been extensively studied because of ...

Hierarchical and Programmable One-Pot Oligosaccharide Synthesis

This article presents a general experimental protocol for programmable one-pot oligosaccharide synthesis and demonstrates how to use Auto-CHO software for generating potential synthetic solutions. The programmable one-pot oligosaccharide synthesis approach is designed to empower fast oligosaccharide synthesis of large amounts using thioglycoside building blocks (BBLs) with the appropriate sequential order of relative reactivity values (RRVs). Auto-CHO is a cross-platform software with a graphical user interface that provides possible synthetic solutions for programmable one-pot oligosaccharide synthesis by searching a BBL library (containing about 150 validated and &#62;50,000 virtual BBLs) with accurately predicted RRVs by support vector regression. The algorithm for hierarchical one-pot synthesis has been implemented in Auto-CHO and uses fragments generated by one-pot reactions as new BBLs. In addition, Auto-CHO allows users to give feedback for virtual BBLs to keep valuable ones for further use. One-pot synthesis of stage-specific embryonic antigen 4 (SSEA-4), which is a pluripotent human embryonic stem cell marker, is demonstrated in this work.

This protocol demonstrates how to use the Auto-CHO software for hierarchical and programmable one-pot synthesis of oligosaccharides. It also describes the general procedure for RRV determination&#160;experiments and one-pot glycosylation of SSEA-4.

Síntese de Oligosacárido de um pote programável e hierárquica

This article presents a general experimental protocol for programmable one-pot oligosaccharide synthesis and demonstrates how to use Auto-CHO software for ...