Funding for this research was provided by the Italian Ministry of Health under the frame of EuroNanoMed II (European Innovative Research &amp; Technological Development Projects in Nanomedicine, project title: ''InNaSERSS'').

1. Síntese de ouro nanobastões Nota: Use água altamente purificada por toda parte. <ol><li> Preparação das sementes de ouro <ol><li> Dissolve-se 364,4 mg de brometo de hexadeciltrimetilamónio (CTAB) em 5 ml de água, sob ultra-sons a 40 ° C até a solução se tornar clara. Deixar a solução de CTAB arrefecer até à temperatura ambiente. </li><li> Separadamente, preparar 5 ml de ácido tetracloroáurico (HAuCl 4) em água (0,5 mM). </li><li> Adicionar a solução de HAuCl 4 para a solução de CTAB sob agitação magnética vigorosa, mantendo a temperatura constante a 27 ° C. </li><li> Preparar 600 ul de boro-hidreto de sódio (NaBH4) em solução de água (10 mM) a 4 ° C. Adicionar esta solução à mistura, sob agitação vigorosa. Verifique se a cor da solução muda imediatamente de amarelo para marrom. </li><li> Agita-se a suspensão durante 20 min antes da utilização. Conserve a suspensão sementes por não mais de 24 horas a tempera quartotura. </li><li> Verificar as dimensões das sementes usando um espectrofotómetro de UV-Vis. Certifique-se de que as sementes estão suficientemente pequeno (cerca de 2 nm) para ser utilizado na preparação de nanorods ouro por espectroscopia de UV-visível. Nota: Espectro deve ser semelhante ao que é apresentado na Figura 1 sementes maiores, identificados pela presença de um pico em torno de 505-520 nm plasmónico não devem ser usados ​​porque são susceptíveis de produzir nanopartículas esféricas.. </li></ol></li><li> Preparação da &quot;solução de crescimento&quot; de nanobastões de ouro. <ol><li> Dissolve-se 182,2 mg de CTAB em conjunto com 22 mg de hidroquinona em 5 ml de água a 40 ° C, utilizando ultra-sons. Arrefecer a solução para 27 ° C. </li><li> Preparar 200 ul de nitrato de prata mM 4 (AgNO 3). </li><li> Separadamente, preparar 5 ml de uma solução 1 mM de ácido tetracloroáurico (HAuCl 4). </li><li> Primeiro adicione a solução de nitrato de prata preparada no passo 1.2.2. Em seguida, adicione o HAuCl 4 solução preparada no passo 1.2.3 para a solução de CTAB e hidroquinona preparado no passo 1.2.1, sob agitação magnética. </li><li> Imediatamente depois, adicionar sob agitação magnética de 12 ul da suspensão de sementes previamente preparado de acordo com o protocolo relatado no passo 1.1 e deixar que o início da reacção. Verifique se a suspensão muda de cor em cerca de 30 min. </li><li> Controlar a formação dos nanobastões, verificando o espectro UV-visível da suspensão, como descrito no capítulo 4, a cada 5 minutos. Prosseguir até que o espectro é estável. Para permitir a formação completa dos nanorods, deixar a suspensão sob agitação durante mais 30 minutos (Figura 2). </li><li> Dividir a suspensão em tubos (1 ml de suspensão para cada tubo) e centrifugar a 10000 xg durante 10 min. nanorods ouro formar um precipitado escuro no fundo do tubo. </li><li> Ressuspender o precipitado de cada tubo em 1 ml de água. Misture o conteúdo dos tubos e armazenar o suspension de nanobastões de ouro à temperatura ambiente. </li><li> Caracterizar os nanobastões obtidas por microscopia eletrônica de espectroscopia e transmissão UV-visível como descrito no ponto 4 (Figura 3). </li></ol></li></ol> 2. Ajuste a relação de aspecto de nanobastões pela variação da concentração de íons Ag + <ol><li> Prepara-se uma solução de nitrato de prata com uma concentração de 4 mM, dissolvendo 3,4 mg de AgNO3 em 5 ml de água. </li><li> Prepara-se três frascos diferentes a solução com CTAB e hidroquinona como descrito na secção 1.2.1, respectivamente e adicionar 100 ul, 150 ul e 200 ul de solução de nitrato de prata. </li><li> Adicione o 4 solução HAuCl acordo com preparada para o passo 1.2.3 e prosseguir com a preparação de nanobastões de ouro, como descrito a partir do ponto 1.2.5. </li><li> Caracterizar os nanobastões obtidos por espectroscopia UV-visível e microscopia eletrônica de transmissão. Tubos de ensaio com menores quantidades de Ag + resultar em nanorods mais curtos (proporção de 2 e 2,2, respectivamente) (Figura 4). </li></ol> 3. Ajustando a Relação de Aspecto da nanobastões pela variação da concentração de CTAB <ol><li> Preparar diferentes lotes de ouro nanorods com diferentes concentrações de CTAB na &quot;solução de crescimento&quot;. Use concentrações de 10 a 100 mm para produzir nanobastões de ouro com tamanho diferente e relação de aspecto. As concentrações de CTAB utilizados em cada experiência estão resumidos na Tabela 1 com a correspondente quantidade de miligramas utilizado. Dissolve-se as diferentes quantidades de CTAB sempre com 22 mg de hidroquinona em 5 ml de água. </li><li> Adicionar 200 ul de solução de nitrato de prata (preparado de acordo com o passo 1.2.2) e 5 ml de HAuCl 4 solução de (preparada de acordo como descrito no passo 1.2.3) em cada frasco, sob agitação magnética. </li><li> Adicionar 12 ul de suspensão de sementes e observar a mudança de cor da mistura final. </li><li> Parea agitação quando a cor da suspensão e o espectro de UV-visível são estabilizadas; o tempo de reacção depende da concentração de CTAB na solução de crescimento. </li><li> Centrifugar a 10000 xg durante 10 min e ressuspender em água. </li><li> Caracterizar os nanobastões obtidos por espectroscopia UV-visível e microscopia eletrônica de transmissão. Uma menor concentração de CTAB irá resultar em nanorods mais curtos, enquanto uma concentração mais elevada dará mais longos, mas maiores nanorods. Por contrário a proporção dos nanorods aspecto será maior na gama de cerca de 40-50 mM e irá diminuir tanto a concentrações mais baixas e mais altas (Figura 5 e Figura 6). </li></ol> 4. Caracterização de ouro nanobastões <ol><li> Espectroscopia de UV-visível <ol><li> Dilui-se 100 ul de solução nanorods com 400 ul de água num micro-cuvete de plástico e adquirir o espectro de absorção no UV-visível (comprimento de onda entre 400 e 840 nm)de acordo com o protocolo do fabricante. </li><li> Recolhe espectros de UV-visível (comprimento de onda entre 400 e 840 nm) da solução de crescimento a cada 5 minutos, a fim de estudar a cinética da reacção. </li></ol></li><li> Microscopia Eletrônica de Transmissão (TEM) <ol><li> Recolhe imagens TEM de cada amostra de nanorods, para a medição do tamanho e da proporção de aspecto nanorods obtidos. Preparar as amostras colocando uma gota de suspensão (4 uL) para uma ultra-finas grelhas de cobre de malha 200 revestidas com Formvar e deixar secar ao ar a 4 ° C. Analisar a amostra a MET usando uma voltagem de aceleração de 200 kV, de acordo com o protocolo do fabricante. </li></ol></li></ol>

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The authors have nothing to disclose.

O protocolo aqui apresentado é aplicável a hidroquinona, uma molécula aromática caracterizada por um fraco potencial de redução, para produzir nanorods ouro. Existem duas principais vantagens da presente protocolo para a via sintética mais vulgarmente empregue com base na utilização de ácido ascórbico: a primeira é que a hidroquinona é capaz de reduzir quase quantitativamente os iões de ouro que permitam a produção de uma maior quantidade de nanorods ouro 11 A. Esta última é dada pelo facto ...

As nanopartículas de ouro (AuNPs) são um dos mais difundidos e nanoestruturas promissores para ser utilizada em aplicações biomédicas. A sua utilização é essencial em muitas ponto-de-cuidado diagnóstico in vitro produtos 1 Eles têm sido propostos como uma ferramenta eficaz para um certo número de outras aplicações diferentes:., Como um agente de contraste em estudos de imagem, 2 como um sistema de entrega de droga 3 e quanto drogas para a termoterapia induzida pela luz (ou terapia fototérmico). 4 o grande potencial de AuNPs conduziu, nos últimos vinte anos, intensa investigação sobre o desenvolvimento de nova síntese que é capaz de aumentar o controlo sobre o tamanho e a forma obtida. 5 Isto é porque diferentes tipos de AuNPs são, de facto, mais adequado do que outros para aplicações específicas. Entre os diferentes nanoestruturas de ouro, nanorods ouro (AuNRs) têm emergido como um dos sistemas mais interessantes. AuNRs são caracterizados por dois Plasmopicos nic associados com a oscilação de electrões ao longo do eixo longitudinal e os eixos transversais, respectivamente. 6 É particularmente importante que a posição do pico longitudinal mais intenso pode ser sintonizado precisamente entre 620 e 800 nm, dependendo da relação das hastes aspecto . Esta região corresponde à janela biológica, 7 em que os tecidos humanos quase não absorvem a luz, permitindo o desenvolvimento de um número de aplicações fotónicas in vivo envolvendo AuNPs. Apesar de um grande interesse por este tipo de nanoestruturas, os protocolos de síntese para a preparação de AuNRs sofrem de várias limitações. Na maioria dos casos, nanorods são preparados de acordo com um método de dois passos desenvolvida por Sau e colegas de trabalho. 8 no seu protocolo, nanorods são sintetizados por redução de iões de ouro, utilizando o ácido ascórbico em presença de sementes de ouro pré-formados, os iões de prata e uma grande quantidade de brometo de hexadecil-trimetilamónio (CTAB), ACsurfactante linear ationic. O inconveniente deste protocolo é de que o rendimento de redução dos iões de ouro é relativamente baixa (cerca de 20%) 9 e que uma elevada quantidade de CTAB, um reagente dispendioso que é responsável por mais de metade do custo total para os reagentes na síntese, é preciso. O desenvolvimento de uma via de síntese nova e mais eficaz é daí considerada como sendo uma importante necessidade, permitindo a difusão de abordagens com base em biomédicas AuNRs. Na primeira parte do presente trabalho, apresentamos um protocolo otimizado para a preparação de AuNR tendo uma proporção de cerca de três aspectos. A síntese é baseada no uso de hidroquinona como um agente redutor suave e que permite a preparação de AuNR com uma redução de quase quantitativa de iões de ouro, fazendo uso de uma quantidade reduzida de CTAB. 10 Este protocolo para a preparação dos AuNRs baseia numa abordagem em duas fases em que as sementes de ouro são usados ​​em uma &quot;Sol crescimentoution &quot;. Na segunda parte, vamos mostrar como finamente ajustar o tamanho e formato do AuNR obtido de duas maneiras. A primeira forma, semelhante ao protocolo padrão à base de ácido ascórbico, é para variar a quantidade de iões de prata presentes na &quot;solução de crescimento&quot;. A segunda maneira baseia-se na variação da quantidade de CTAB que pode ser reduzida até uma concentração de 10 mM (perto da concentração micelar crítica relatado pelo fornecedor) para se obter nanorods curtas bem definidos.

<table border="0" cellpadding="0" cellspacing="0" width="756">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Gold(III) chloride trihydrate</td>
			<td style="width:115px;">Sigma Aldrich</td>
			<td style="width:99px;">520918</td>
			<td style="width:327px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Hydroquinone</td>
			<td>Sigma Aldrich</td>
			<td>H17902</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Silver Nitrate</td>
			<td>Sigma Aldrich</td>
			<td>209139</td>
			<td>toxic</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Sodium Borohydride</td>
			<td>Sigma Aldrich</td>
			<td>480886</td>
			<td></td>
		</tr>
		<tr height="148">
			<td height="148" style="height:148px;width:216px;">Hexadecyltrimethylammonium bromide (CTAB)</td>
			<td>Sigma Aldrich</td>
			<td>H5882</td>
			<td style="width:327px;">Acute Tox. (oral). In this study we tested three different batches of CTAB (H5882) from Sigma Aldrich. Two of them were marked as made in China while one as made in India. In our experience only the batches marked as made in China were effective for the preparation of AuNR</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Spectrophotometer</td>
			<td style="width:115px;">Thermo scientific&#160;</td>
			<td style="width:99px;">Nanodrop 2000C</td>
			<td></td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:216px;">TEM</td>
			<td style="width:115px;">JEOL</td>
			<td>2100</td>
			<td></td>
		</tr>
	</tbody>
</table>

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.

Os espectros de UV visível das sementes de ouro pode ser visto na Figura 1. Os espectros de UV visível adquiridas em tempos diferentes após a injecção das sementes de ouro são apresentados na Figura 2. Imagens Os espectros de UV visível e de microscopia electrónica de transmissão (TEM) das nanorods ouro obtidos são mostrados na Figura 3. microscópica de UV visível e os espectros de transmissão de electrão (TEM) de imagens n...

Watch this Scientific Journal Video about Hydroquinone Based Synthesis of Gold Nanorods at JoVE.com

Hydroquinone Based Synthesis of Gold Nanorods

Este documento descreve um protocolo para a síntese de ouro nanorods, baseado no uso de hidroquinona como agente de redução, mais os diferentes mecanismos para controlar o tamanho e a relação de aspecto.

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 ...

hydroquinone-based-synthesis-of-gold-nanorods

Research

JoVE Journal

Chemistry

13.6K visualizações.  Fondazione Don Carlo Gnocchi ONLUS (Don Carlo Gnocchi Foundation).  Este documento descreve um protocolo para a síntese de ouro nanorods, baseado no uso de hidroquinona como agente de redução, mais os diferentes mecanismos para controlar o tamanho e a relação de aspecto. 

Vídeo: Hydroquinone Based Synthesis of Gold Nanorods

Template Directed Synthesis of Plasmonic Gold Nanotubes with Tunable IR Absorbance

A nearly parallel array of pores can be produced by anodizing aluminum foils in acidic environments1, 2. Applications of anodic aluminum oxide (AAO) membranes have been under development since the 1990's and have become a common method to template the synthesis of high aspect ratio nanostructures, mostly by electrochemical growth or pore-wetting. Recently, these membranes have become commercially available in a wide range of pore sizes and densities, leading to an extensive library of functional nanostructures being synthesized from AAO membranes. These include composite nanorods, nanowires and nanotubes made of metals, inorganic materials or polymers 3-10. Nanoporous membranes have been used to synthesize nanoparticle and nanotube arrays that perform well as refractive index sensors, plasmonic biosensors, or surface enhanced Raman spectroscopy (SERS) substrates 11-16, as well as a wide range of other fields such as photo-thermal heating 17, permselective transport 18, 19, catalysis 20, microfluidics 21, and electrochemical sensing 22, 23. Here, we report a novel procedure to prepare gold nanotubes in AAO membranes. Hollow nanostructures have potential application in plasmonic and SERS sensing, and we anticipate these gold nanotubes will allow for high sensitivity and strong plasmon signals, arising from decreased material dampening 15.

Solution-suspendable gold nanotubes with controlled dimensions can be synthesized by electrochemical deposition in porous anodic aluminum oxide (AAO) membranes using a hydrophobic polymer core. Gold nanotubes and nanotube arrays hold promise for applications in plasmonic biosensing, surface-enhanced Raman spectroscopy, photo-thermal heating, ionic and molecular transport, microfluidics, catalysis and electrochemical sensing.

Dirigido modelo de síntese de nanotubos de Ouro plasmônicos com Absorbância IR Tunable

A nearly parallel array of pores can be produced by anodizing aluminum foils in acidic environments1, 2. Applications of anodic aluminum oxide (AAO) ...

Química

Synthesis and Catalytic Performance of Gold Intercalated in the Walls of Mesoporous Silica

As a promising catalytically active nano reactor, gold nanoparticles intercalated in mesoporous silica (GMS) were successfully synthesized and properties of the materials were investigated. We used a one pot sol-gel approach to intercalate gold nano particles in the walls of mesoporous silica. To start with the synthesis, P123 was used as template to form micelles. Then TESPTS was used as a surface modification agent to intercalate gold nano particles. Following this process, TEOS was added in as a silica source which underwent a polymerization process in acid environment. After hydrothermal processing and calcination, the final product was acquired. Several techniques were utilized to characterize the porosity, morphology and structure of the gold intercalated mesoporous silica. The results showed a stable structure of mesoporous silica after gold intercalation. Through the oxidation of benzyl alcohol as a benchmark reaction, the GMS materials showed high selectivity and recyclability.

Here, we present a protocol with a sol-gel process to synthesize gold intercalated in the walls of mesoporous materials (GMS), which is confirmed to possess a mesoporous matrix with gold intercalated in the walls imparting great stability and recyclability.

Síntese e desempenho catalítico de ouro intercalados nas paredes de mesoporosos Silica

As a promising catalytically active nano reactor, gold nanoparticles intercalated in mesoporous silica (GMS) were successfully synthesized and properties ...

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

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

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

Um método simples para o tamanho Síntese controlada de estáveis ​​Oligoméricas Clusters de nanopartículas em condições ambientais

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

Photochemical Oxidative Growth of Iridium Oxide Nanoparticles on CdSe@CdS Nanorods

We demonstrate a procedure for the photochemical oxidative growth of iridium oxide catalysts on the surface of seeded cadmium selenide-cadmium sulfide (CdSe@CdS) nanorod photocatalysts. Seeded rods are grown using a colloidal hot-injection method and then moved to an aqueous medium by ligand exchange. CdSe@CdS nanorods, an iridium precursor and other salts are mixed and illuminated. The deposition process is initiated by absorption of photons by the semiconductor particle, which results with formation of charge carriers that are used to promote redox reactions. To insure photochemical oxidative growth we used an electron scavenger. The photogenerated holes oxidize the iridium precursor, apparently in a mediated oxidative pathway. This results in the growth of high quality crystalline iridium oxide particles, ranging from 0.5 nm to about 3 nm, along the surface of the rod. Iridium oxide grown on CdSe@CdS heterostructures was studied by a variety of characterization methods, in order to evaluate its characteristics and quality. We explored means for control over particle size, crystallinity, deposition location on the CdS rod, and composition. Illumination time and excitation wavelength were found to be key parameters for such control. The influence of different growth conditions and the characterization of these heterostructures are described alongside a detailed description of their synthesis. Of significance is the fact that the addition of iridium oxide afforded the rods astounding photochemical stability under prolonged illumination in pure water (alleviating the requirement for hole scavengers).

A protocol for the photochemical oxidative growth of small crystalline iridium oxide nanoparticles on the surface of CdSe@CdS seeded rod nanoparticles is presented.

Fotoquímica Crescimento oxidativo da Iridium nanopartículas de óxido de CdSe @ CdS nanobastões

We demonstrate a procedure for the photochemical oxidative growth of iridium oxide catalysts on the surface of seeded cadmium selenide-cadmium sulfide ...

Synthesis and Evaluation of a Ruthenium-based Mitochondrial Calcium Uptake Inhibitor

We detail the synthesis and purification of a mitochondrial calcium uptake inhibitor, [(OH2)(NH3)4Ru(&#181;-O)Ru(NH3)4(OH2)]5+. The optimized synthesis of this compound commences from [Ru(NH3)5Cl]Cl2 in 1 M NH4OH in a closed container, yielding a green solution. Purification is accomplished with cation-exchange chromatography. This compound is characterized and verified to be pure by UV-vis and IR spectroscopy. The mitochondrial calcium uptake inhibitory properties are assessed in permeabilized HeLa cells by fluorescence spectroscopy.

A protocol for the synthesis, purification, and characterization of a ruthenium-based inhibitor of mitochondrial calcium uptake is presented. A procedure to evaluate its efficacy in permeabilized mammalian cells is demonstrated.

Síntese e avaliação de um inibidor de absorção de cálcio mitocondrial rutênio-baseado

We detail the synthesis and purification of a mitochondrial calcium uptake inhibitor, [(OH2)(NH3)4Ru(&#181;-O)Ru(NH3)4(OH2)]5+. The optimized synthesis of ...

Rapid Nanoprobe Signal Enhancement by In Situ Gold Nanoparticle Synthesis

The use of nanoprobes such as gold, silver, silica or iron-oxide nanoparticles as detection reagents in bioanalytical assays can enable high sensitivity and convenient colorimetric readout. However, high densities of nanoparticles are typically needed for detection. The available synthesis-based enhancement protocols are either limited to gold and silver nanoparticles or rely on precise enzymatic control and optimization. Here, we present a protocol to enhance the colorimetric readout of gold, silver, silica, and iron oxide nanoprobes. It was observed that the colorimetric signal can be improved by up to a 10000-fold factor. The basis for such signal enhancement strategies is the chemical reduction of Au3+ to Au0. There are several chemical reactions that enable the reduction of Au3+ to Au0. In the protocol, Good&#39;s buffers and H2O2 are used and it is possible to favor the deposition of Au0 onto the surface of existing nanoprobes, in detriment of the formation of new gold nanoparticles. The protocol consists of the incubation of the microarray with a solution consisting of chloroauric acid and H2O2 in 2-(N-morpholino)ethanesulfonic acid pH 6 buffer following the nanoprobe-based detection assay. The enhancement solution can be applied to paper and glass-based sensors. Moreover, it can be used in commercially available immunoassays as demonstrated by the application of the method to a commercial allergen microarray. The signal development requires less than 5 min of incubation with the enhancement solution and the readout can be assessed by naked eye or low-end image acquisition devices such as a table-top scanner or a digital camera.

Rapid Nanoprobe Signal Enhancement by In Situ Gold Nanoparticle Synthesis

In this work, a protocol for signal enhancement of nanoprobe-based biosensing is presented. The protocol is based on the reduction of chloroauric acid onto the surface of existing nanoprobes that consist of gold, silver, silica or iron-oxide nanoparticles.

Sinal de nanossondas rápida realce pela síntese de nanopartículas de ouro em Situ

The use of nanoprobes such as gold, silver, silica or iron-oxide nanoparticles as detection reagents in bioanalytical assays can enable high sensitivity ...

Synthesis of Bimetallic Pt/Sn-based Nanoparticles in Ionic Liquids

We demonstrate a method for the synthesis of bimetallic nanoparticles consisting of Pt and Sn. A synthesis strategy is used in which the particular physico-chemical properties of ionic liquids (ILs) are exploited to control both nucleation and growth processes. The nanoparticles form colloidal sols of very high colloidal stability in the IL, which is particularly interesting in view of their use as quasi-homogeneous catalysts. Procedures for both nanoparticle extraction in conventional solvents and for nanoparticle precipitation are presented. The size, structure and composition of the synthesized nanocrystals are confirmed using inductively coupled plasma atomic emission spectroscopy (ICP-AES), X-ray diffraction analysis (XRD) and transmission electron microscopy (TEM) with energy-dispersive X-ray spectroscopy (EDX). By this, we show that the nanocrystals are random-type alloy and of small (2-3 nm) size. The catalytic activity and selectivity in the hydrogenation of &#945;,&#946;-unsaturated aldehydes is tested in a semi-continuous batch-type reactor. In this context, the bimetallic Pt/Sn-based nanoparticles reveal a high selectivity towards the unsaturated alcohol.

A protocol for the synthesis of bimetallic nanoparticles in ionic liquids and the procedure of their catalytic testing in the selective hydrogenation of unsaturated aldehydes are described.

Síntese de Nanopartículas Bimetálicas à Base de Pt/Sn em Líquidos Iônicos

We demonstrate a method for the synthesis of bimetallic nanoparticles consisting of Pt and Sn. A synthesis strategy is used in which the particular ...

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 ...

Assembly of Gold Nanorods into Chiral Plasmonic Metamolecules Using DNA Origami Templates

The inherent addressability of DNA origami structures makes them ideal templates for the arrangement of metal nanoparticles into complex plasmonic nanostructures. The high spatial precision of a DNA origami-templated assembly allows controlling the coupling between plasmonic resonances of individual particles and enables tailoring optical properties of the constructed nanostructures. Recently, chiral plasmonic systems attracted a lot of attention due to the strong correlation between the spatial configuration of plasmonic assemblies and their optical responses (e.g., circular dichroism [CD]). In this protocol, we describe the whole workflow for the generation of DNA origami-based chiral assemblies of gold nanorods (AuNRs). The protocol includes a detailed description of the design principles and experimental procedures for the fabrication of DNA origami templates, the synthesis of AuNRs, and the assembly of origami-AuNR structures. In addition, the characterization of structures using transmission electron microscopy (TEM) and CD spectroscopy is included. The described protocol is not limited to chiral configurations and can be adapted for the construction of various plasmonic architectures.

We describe the detailed protocol for the DNA origami-based assembly of gold nanorods into chiral plasmonic metamolecules with strong chiroptical responses. The protocol is not limited to chiral configurations and can be easily adapted for the fabrication of various plasmonic architectures.

Montagem de Nanobastões de Ouro em Metamoléculas Plasmônicas Quirais Usando Modelos de Origami de DNA

The inherent addressability of DNA origami structures makes them ideal templates for the arrangement of metal nanoparticles into complex plasmonic ...

Photodeposition of Pd onto Colloidal Au Nanorods by Surface Plasmon Excitation

A protocol is described to photocatalytically guide Pd deposition onto Au nanorods (AuNR) using surface plasmon resonance (SPR). Excited plasmonic hot electrons upon SPR irradiation drive reductive deposition of Pd on colloidal AuNR in the presence of [PdCl4]2-. Plasmon-driven reduction of secondary metals potentiates covalent, sub-wavelength deposition at targeted locations coinciding with electric field &#8220;hot-spots&#8221; of the plasmonic substrate using an external field (e.g., laser). The process described herein details a solution-phase deposition of a catalytically-active noble metal (Pd) from a transition metal halide salt (H2PdCl4) onto aqueously-suspended, anisotropic plasmonic structures (AuNR). The solution-phase process is amenable to making other bimetallic architectures. Transmission UV-vis monitoring of the photochemical reaction, coupled with ex situ XPS and statistical TEM analysis, provide immediate experimental feedback to evaluate properties of the bimetallic structures as they evolve during the photocatalytic reaction. Resonant plasmon irradiation of AuNR in the presence of [PdCl4]2- creates a thin, covalently-bound Pd0 shell without any significant dampening effect on its plasmonic behavior in this representative experiment/batch. Overall, plasmonic photodeposition offers an alternative route for high-volume, economical synthesis of optoelectronic materials with sub-5 nm features (e.g., heterometallic photocatalysts or optoelectronic interconnects).

A protocol for anisotropic photodeposition of Pd onto aqueously-suspended Au nanorods via localized surface plasmon excitation is presented.

Fotodeposição de PD em au Nanorods coloidal pela excitação de superfície Plasmon

A protocol is described to photocatalytically guide Pd deposition onto Au nanorods (AuNR) using surface plasmon resonance (SPR). Excited plasmonic hot ...