This work was supported by the Marie Curie International Reintegration Grant (EP7). P. D. acknowledges the support of the Israel Council for Higher Education.

1. Sugestão Modificação <ol><li> Compra de nitreto de silício (Si 3 N 4) cantilevers de AFM com pontas de silício (raio cantilever nominal de ~ 2 nm). </li><li> Limpar cada cantilever AFM por imersão em etanol anidro durante 20 min. Seca-se à temperatura ambiente. Em seguida, tratar as consolas por expondo-os a O2 do plasma durante 5 min. </li><li> Suspender as pontas limpas acima (3 cm) contendo uma solução metiltrietoxisilano e 3- (aminopropil) silano em uma proporção de 15: 1 (v / v) em um exsicador sob uma atmosfera inerte (azoto ou árgon) e ligar o exsicador até uma bomba de vácuo. Vácuo durante 2 horas para formar uma monocamada destes dois tipos de compostos de silano misturadas. </li><li> Use um suporte de ponta metálica (fabricada para este processo) para colocar as dicas em uma placa quente. Em seguida, secar as pontas durante 10 minutos a 70 ° C sob condições atmosféricas. Antes do uso, limpe a placa quente, titular metálico e pinças usando etanol. </li><li> Arrefecer as dicas no quarto temperatura, e depois mergulhar as pontas em uma solução de Fluorenilmetiloxicarbonilo-PEG-N-hidroxi-succinimida (Fmoc-PEG-NHS, PM 5000 Da) a uma concentração de 5 mM em clorofórmio contendo 0,5% (v / v) de trietilamina durante 1 h a temperatura do quarto. </li><li> Mergulhe as pontas em clorofórmio durante 5 minutos e, em seguida, mergulhá-lo em dimetilformamida (DMF) durante mais 5 minutos. A fim de desproteger o grupo Fmoc de as moléculas de PEG ligadas, mergulhar as pontas em piperidina a 20% (v / v) em DMF durante 30 min. Mergulhar as pontas em DMF, durante 4 minutos e, em seguida, em N-metil-2-pirrolidona (NMP) para adicional de 4 minutos. Repita o sequencial mergulhar três vezes. </li><li> Para o acoplamento de aminoácidos, imergir as pontas em uma solução contendo N-terminal de amino ácido protegido (AA) / di-isopropiletilamina (DIPEA) / 2- (1H-benzotriazol-1-il) -1,1,3,3-tetrametilurónio hexafluophosphate (HBTU), numa proporção molar de 1: 1: 1 com uma concentração total de 30 mM em 5 mL de NMP durante 1,5 h. </li><li> Para o acoplamento de péptidos, mergulhe as pontas em uma solução cont 5 mLaining 40 mg do péptido protegido (terminal N e cadeias laterais, por exemplo, Fmoc-Gln (Trt) -Pro-Ala-Ser (tBu) -Ser (tBu) -Arg (PBF) -Tyr (tBu) -COOH). , 15 mg de 2- (1H-benzotriazol-1-il) -1,1,3,3-tetrametilurio hexafluorofosfato (HBTU), e 5 ml de DIPEA em NMP durante 2 h. </li><li> Mergulhe as pontas em NMP durante 4 min. Em seguida, para proteger a mandrilagem livre / não reagido NH2 pelo grupo acetilo, mergulhar as pontas durante 30 min numa mistura de anidrido acético / DIPEA a uma razão molar de 4: 1 e uma concentração total de 0,65 M em NMP. </li><li> Para o acoplamento de péptido, realizar duas etapas adicionais. <ol><li> A fim de desproteger as cadeias laterais do péptido, imergir as pontas em uma solução contendo 95% de TFA, 2,5% de tri-isopropilsilano e 2,5% de água durante 1 h, e, em seguida, lava-se com clorofórmio e DMF. </li><li> De modo a remover o grupo Fmoc do péptido, imergir as pontas em piperidina a 20% (v / v) em DMF durante 30 min. </li></ol></li><li> Sequencialmente mergulhar o péptido / amino ácido-funcionalizard dicas para quatro minutos cada em DMF (para péptidos) ou NMP (para os aminoácidos), clorofórmio, 50% de etanol e água. Por fim, seque a ponta no ar. </li></ol> 2. Preparação de Superfície <ol><li> Prepare mica. Clivar os substratos (9,9 mm de diâmetro) antes de cada utilização, usando fita adesiva. Em seguida, lavar as superfícies com água destilada tripla (TPB). </li><li> Prepare TiO 2 -Revestido silício. <ol><li> Cortar o wafer de silício (100) em 2 cm quadrados usando uma caneta de diamante. </li><li> Colocar o substrato num tubo de ensaio de 15 ml cheio com acetona e sonicar durante cinco minutos num banho de ultra-sons. Em seguida, colocar esta superfície de um tubo de ensaio de 15 ml cheio com isopropanol e sonicar durante 5 minutos. Secar o substrato utilizando nitrogênio. </li><li> Dissolve-se o agente tensioactivo (por exemplo, BYK-348) em etanol para preparar uma solução a 5% (peso / volume). Em seguida, adicionar 0,02 ml da solução de agente tensioactivo a uma dispersão de 2 2 ml de 30% de TiO. </li><li> A partir da solução resultante, gota-cast 0.2 mL em um substrato de Si limpa. </li><li> Recozer estas superfícies fundidas-gota a 250 ° C durante 2 h em ar. 41 </li></ol></li></ol> 3. única molécula de medidas de força Espectroscopia <ol><li> Anexar a superfície desejada a um suporte metálico de AFM com cola de dois componentes comercialmente disponíveis. Colocar o suporte da metálico no suporte do copo da AFM, que tem a forma de uma pequena placa de Petri. Preencha este suporte com tampão Tris (pH 50 mM = 7,4) ou qualquer meio desejado. Em seguida, coloque o titular no palco AFM baixo do suporte da ponta. </li><li> Calibrar os braços de suporte de AFM com constantes de mola que variam de 10 a 30 pN / nm, utilizando o método de flutuação térmica 26 (incluído no software AFM) com uma incerteza absoluta de cerca de 10%. </li><li> Medir a força da interacção por se aproximar do aminoácido ou ponta funcionalizada-péptido para o substrato até que esteja em contacto com o substrato com uma compressãoforça de ~ 200 pN e, em seguida, imediatamente retrair a ponta a várias velocidades, de 0,1 a 0,8 ^ m / s, para uma distância de ~ 200 nm. </li></ol> Análise 4. Dados <ol><li> Converter os valores de deformação (V) para forçar multiplicando a sensibilidade fotodíodo (V / m) e utilizando a constante da mola determinado experimentalmente. 42 Isto é feito automaticamente pelo software AFM. <ol><li> Para obter curvas FD com um eventos única molécula, ficha várias centenas de curvas (800-1,500). Obter dois picos numa curva de uma única molécula de: o primeiro pico indica interacções não específicas entre a ponta e a superfície e o segundo corresponde ao pico da interacção específica da molécula com a superfície. Quando, a curva FD conter mais do que estes dois picos, descartá-las a partir do cálculo da força mais provável. NOTA: Apenas eventos de adesão individuais são tidas em conta (de 10 a 30% das curvas). 43 </li></ol></li><li&gt; Para calcular a taxa de carregamento aparente, ajuste de pelo menos 50 força vs. curvas distância com a corrente sem-fim-like (WLC) modelo 44 pouco antes da ruptura para obter um conjunto de taxas de carregamento, que são então utilizados para a preparação de histogramas as taxas de carga aparente. Derivar as forças unbinding entre os péptidos ácidos aminados e / superfície do salto em força depois da separação do raio de acção do substrato. </li></ol>

Os autores declaram que não têm interesses financeiros concorrentes.

Os passos 1.3, 1.4 e 1.7 no protocolo deve ser realizado com cuidado extenso e de uma forma muito suave. No passo 1.3, a ponta não deve estar em contacto com a mistura de silano e o processo de silanização deve ser realizada numa atmosfera inerte (de humidade livre). 45 Isto é feito a fim de evitar a formação de camadas múltiplas e porque as moléculas de silano prontamente sofrer hidrólise na presença de humidade. 45 No passo 1.4, a t...

A interacção entre as proteínas e minerais inorgânicos conduz à construção de materiais compósitos com propriedades distintivas. Isto inclui materiais com elevada resistência mecânica ou as propriedades ópticas únicas. 1, 2, por exemplo, a combinação da proteína de colagénio com a hidroxiapatite mineral, quer gera ossos moles ou duras para diferentes funcionalidades. 3 péptidos curtos, também podem ligar-se materiais inorgânicos com alta especificidade. 4, 5, 6 A especificidade destes péptidos foi usado para a criação de novos materiais magnéticos e electrónicos, 7, 8, 9 fabricar materiais nanoestruturados, crescimento de cristais, 10 e sintetizar nanopartículas. 11 Para entender o mecanismo subjacente interações entre peptídeos ou proteínas e materiais inorgânicos, portanto, nos permitem projetar novos materiais compósitos com melhores propriedades de adsorção. Além disso, uma vez que a interfase de implantes com uma resposta imunitária é mediada por proteínas, uma melhor compreensão das interacções de proteínas com materiais inorgânicos vai melhorar a nossa capacidade para conceber implantes. Outra área importante, que envolve proteínas que interagem com superfícies inorgânicas é a fabricação de materiais anti-incrustações. 12, 13, 14, 15 A incrustação biológica é um processo em que organismos indesejáveis anexar a uma superfície. Ele tem muitas implicações prejudiciais sobre nossas vidas. Por exemplo, biofouling de bactérias sobre dispositivos médicos leva a infecções hospitalares. Biofouling de organismos marinhos em barcos e navios de grande porte aumenta o<html> o consumo de combustível. 12, 16, 17, 18 -Molécula única força espectroscopia (SMFS), usando um AFM, pode medir directamente as interacções entre um aminoácido ou um péptido com um substrato. 19, 20, 21, 22, 23, 24, 25, 26 Outros métodos, como a exibição de fagos, 27, 28 microbalança de cristal de quartzo (QCM) 29 ou ressonância de plasma de superfície (SPR) 29, 30, 31, 32,ref &quot;&gt; 33 medida as interações de peptídeos e proteínas para superfícies inorgânicas em massa. 34, 35, 36 Isto significa que os resultados obtidos por estes métodos referem-se a conjuntos de moléculas ou agregados. Em SMFS, uma ou poucas moléculas são fixadas à ponta de AFM e as suas interacções com o substrato desejado é medido. Esta abordagem pode ser expandido para estudar o dobramento de proteínas, puxando a proteína a partir da superfície. Além disso, ele pode ser usado para medir as interacções entre células e proteínas e a ligação dos anticorpos para os seus ligandos. 37, 38, 39, 40 Este artigo descreve detalhadamente como anexar tanto peptídeos ou aminoácidos para a ponta do AFM usando química silanol. Além disso, o documento explica como realizar medições de força e como analisar aresultados.

<table border="0" cellpadding="0" cellspacing="0" width="638">
	<colgroup>
		<col />
		<col />
		<col />
		<col />
	</colgroup>
	<tbody>
		<tr height="173">
			<td height="173" style="height:173px;width:164px;">Silicon nitride (Si3N4) AFM cantilevers with silicon tips</td>
			<td style="width:147px;">Bruker (Camarilo, CA, USA)</td>
			<td style="width:64px;"></td>
			<td style="width:264px;">MSNL10, nominal cantilevers radius ~2 nm&#160;</td>
		</tr>
		<tr height="106">
			<td height="106" style="height:106px;width:164px;">Methyltriethoxysilane&#160;</td>
			<td style="width:147px;">Acros Organics (New Jersey, USA)</td>
			<td style="width:64px;"></td>
			<td style="width:264px;">For Silaylation of the AFM tip&#160;</td>
		</tr>
		<tr height="106">
			<td height="106" style="height:106px;width:164px;">3-(Aminopropyl) triethoxysilane</td>
			<td style="width:147px;">Sigma-Aldrich (Jerusalem, Israel)</td>
			<td style="width:64px;"></td>
			<td style="width:264px;">Used for tip modification&#160;</td>
		</tr>
		<tr height="106">
			<td height="106" style="height:106px;width:164px;">Triisopropylsilane</td>
			<td style="width:147px;">Sigma-Aldrich (Jerusalem, Israel)</td>
			<td style="width:64px;"></td>
			<td style="width:264px;">Used for tip modification</td>
		</tr>
		<tr height="85">
			<td height="85" style="height:85px;width:164px;">N-Ethyldiisopropylamine</td>
			<td style="width:147px;">Alfa-Aesar (Lancashire, UK)</td>
			<td style="width:64px;"></td>
			<td style="width:264px;">Used for tip modification</td>
		</tr>
		<tr height="85">
			<td height="85" style="height:85px;width:164px;">Triethylamine</td>
			<td style="width:147px;">Alfa-Aesar (Lancashire, UK)</td>
			<td style="width:64px;"></td>
			<td style="width:264px;">Used for tip modification</td>
		</tr>
		<tr height="85">
			<td height="85" style="height:85px;width:164px;">Piperidine</td>
			<td style="width:147px;">Alfa-Aesar (Lancashire, UK)</td>
			<td style="width:64px;"></td>
			<td style="width:264px;">Used for tip modification</td>
		</tr>
		<tr height="232">
			<td height="232" style="height:232px;width:164px;">Fluorenylmethyloxycarbonyl-PEG-N-hydroxysuccinimide&#160; (Fmoc-PEG-NHS)</td>
			<td style="width:147px;">Iris Biotech GmbH (Deutschland, Germany)</td>
			<td style="width:64px;"></td>
			<td style="width:264px;">Used as the covalent flexible linker&#160; (MW = 5000 Da)</td>
		</tr>
		<tr height="253">
			<td height="253" style="height:253px;width:164px;">2-(1H-benzotriazol-1-yl)-1,1,3,3,-tetramethyluronium hexafluorophosphate (HBTU)</td>
			<td style="width:147px;">Alfa Aser (Heysham, England)</td>
			<td style="width:64px;"></td>
			<td style="width:264px;">Used as a coupling reagent.&#160;</td>
		</tr>
		<tr height="148">
			<td height="148" style="height:148px;width:164px;">N-methyl-2-pyrrolidone (NMP)</td>
			<td style="width:147px;">Acros Organics (New Jersey, USA)</td>
			<td style="width:64px;"></td>
			<td style="width:264px;">Used as Solvent in Tip modification procedure</td>
		</tr>
		<tr height="148">
			<td height="148" style="height:148px;width:164px;">DMF (dimethylformamide)</td>
			<td style="width:147px;">Merck (Darmstadt, Germany)</td>
			<td style="width:64px;"></td>
			<td style="width:264px;">Used as Solvent in Tip modification procedure</td>
		</tr>
		<tr height="106">
			<td height="106" style="height:106px;width:164px;">Trifluoro acetic acid (TFA)</td>
			<td style="width:147px;">Merck (Darmstadt, Germany)</td>
			<td style="width:64px;"></td>
			<td style="width:264px;"></td>
		</tr>
		<tr height="106">
			<td height="106" style="height:106px;width:164px;">Acetic anhydride</td>
			<td style="width:147px;">Merck (Darmstadt, Germany)</td>
			<td style="width:64px;"></td>
			<td style="width:264px;"></td>
		</tr>
		<tr height="106">
			<td height="106" style="height:106px;width:164px;">Peptides</td>
			<td style="width:147px;">GL Biochem (Shanghai, China).</td>
			<td style="width:64px;"></td>
			<td style="width:264px;"></td>
		</tr>
		<tr height="106">
			<td height="106" style="height:106px;width:164px;">Phenylalanine and Tyrosine&#160;</td>
			<td style="width:147px;">Biochem (Darmstadt, Germany)&#160;</td>
			<td style="width:64px;"></td>
			<td style="width:264px;"></td>
		</tr>
		<tr height="240">
			<td height="361" rowspan="7" style="height:361px;width:164px;">30% TiO2 dispersion in the mixture of solvent 2-(2-Methoxyethoxy) ethanol (DEGME) and Ethyl 3-Ethoxypropionate (EEP)</td>
			<td rowspan="7" style="width:147px;">Applied Vision Laboratories (Jerusalem, Israel)</td>
			<td rowspan="7" style="width:64px;"></td>
			<td rowspan="7" style="width:264px;">(30%) in the mixture of solvent 2-(2 Methoxyethoxy) ethanol (DEGME) and Ethyl 3-Ethoxypropionate (EEP)</td>
		</tr>
		<tr height="20">
		</tr>
		<tr height="20">
		</tr>
		<tr height="20">
		</tr>
		<tr height="20">
		</tr>
		<tr height="20">
		</tr>
		<tr height="21">
		</tr>
		<tr height="148">
			<td height="148" style="height:148px;width:164px;">Mica substrates</td>
			<td style="width:147px;">TED PELLA, INC. (Redding, California, USA)</td>
			<td style="width:64px;"></td>
			<td style="width:264px;">9.9 mm diameter</td>
		</tr>
	</tbody>
</table>

insights into the interactions of amino acids and peptides with inorganic materials using single-molecule force spectroscopy

As interacções entre as proteínas ou péptidos e materiais inorgânicos levar a vários processos interessantes. Por exemplo, combinando proteínas com minerais conduz à formação de materiais compósitos com propriedades únicas. Além disso, o processo de incrustação biológica indesejável é iniciada pela adsorção de biomoléculas, principalmente proteínas, nas superfícies. Esta camada orgânica é uma camada de adesão de bactérias e que lhes permite interagir com a superfície. Compreender as forças fundamentais que governam as interações na interface orgânica-inorgânica, é importante para muitas áreas de pesquisa e poderia levar à concepção de novos materiais para aplicações ópticas, mecânicas e biomédicas. Este artigo demonstra uma técnica de espectroscopia de força única molécula que utiliza um AFM para medir a força de aderência entre ambos péptidos ou aminoácidos e superfícies inorgânicas bem definidas. Esta técnica envolve um protocolo para a fixação da biomolécula a AFMponta através de um ligante flexível covalente e única molécula de medidas de espectroscopia de força por parte microscópio de força atômica. Além disso, uma análise dessas medidas está incluída.

A Figura 1 apresenta o procedimento de modificação de ponta. No primeiro passo, um tratamento com plasma modifica a superfície da ponta de nitreto de silício. A ponta apresenta grupos OH. Estes grupos serão, em seguida, reagir com os silanos. No final deste passo, a superfície da ponta vai ser coberta por grupos -NH2 livres. Estas aminas livres vai então reagir com Fmoc-PEG-NHS, um ligante covalente. O grupo Fmoc do ligante é removido por PEG pipyridin...

Watch this Scientific Journal Video about Insights into the Interactions of Amino Acids and Peptides with Inorganic Materials Using Single-Molecule Force Spectroscopy at JoVE.com

Insights into the Interactions of Amino Acids and Peptides with Inorganic Materials Using Single-Molecule Force Spectroscopy

Aqui apresentamos um protocolo para medir a força das interações entre uma superfície inorgânica bem definida e tanto peptídeos ou aminoácidos por única molécula de medidas de espectroscopia de força utilizando um microscópio de força atômica (AFM). As informações obtidas a partir da medição é importante para entender melhor a interfase material de peptídeo-inorgânico.

Insights sobre as interações de aminoácidos e peptídeos com Materiais Inorgânicos Usando Single-Molecule Força Spectroscopy

The interactions between proteins or peptides and inorganic materials lead to several interesting processes. For example, combining proteins with minerals ...

insights-into-interactions-amino-acids-peptides-with-inorganic

Research

JoVE Journal

Chemistry

8.0K visualizações.  The Hebrew University of Jerusalem.  Aqui apresentamos um protocolo para medir a força das interações entre uma superfície inorgânica bem definida e tanto peptídeos ou aminoácidos por única molécula de medidas de espectroscopia de força utilizando um microscópio de força atômica (AFM). As informações obtidas a partir da medição é importante para entender melhor a interfase material de peptídeo-inorgânico. 

Vídeo: Insights into the Interactions of Amino Acids and Peptides with Inorganic Materials Using Single-Molecule Force Spectroscopy

Formation of Ordered Biomolecular Structures by the Self-assembly of Short Peptides

In nature, complex functional structures are formed by the self-assembly of biomolecules under mild conditions. Understanding the forces that control self-assembly and mimicking this process in vitro will bring about major advances in the areas of materials science and nanotechnology. Among the available biological building blocks, peptides have several advantages as they present substantial diversity, their synthesis in large scale is straightforward, and they can easily be modified with biological and chemical entities1,2. Several classes of designed peptides such as cyclic peptides, amphiphile peptides and peptide-conjugates self-assemble into ordered structures in solution. Homoaromatic dipeptides, are a class of short self-assembled peptides that contain all the molecular information needed to form ordered structures such as nanotubes, spheres and fibrils3-8. A large variety of these peptides is commercially available.
This paper presents a procedure that leads to the formation of ordered structures by the self-assembly of homoaromatic peptides. The protocol requires only commercial reagents and basic laboratory equipment. In addition, the paper describes some of the methods available for the characterization of peptide-based assemblies. These methods include electron and atomic force microscopy and Fourier-Transform Infrared Spectroscopy (FT-IR). Moreover, the manuscript demonstrates the blending of peptides (coassembly) and the formation of a &#34;beads on a string&#34;-like structure by this process.9 The protocols presented here can be adapted to other classes of peptides or biological building blocks and can potentially lead to the discovery of new peptide-based structures and to better control of their assembly.

This paper describes the formation of highly ordered peptide-based structures by the spontaneous process of self-assembly. The method utilizes commercially available peptides and common lab equipment. This technique can be applied to a large variety of peptides and may lead to the discovery of new peptide-based assemblies.

A formação de estruturas biomoleculares ordenada pelo auto-montagem de pequenos peptídeos

In nature, complex functional structures are formed by the self-assembly of biomolecules under mild conditions. Understanding the forces that control ...

Química

Preparation of Silica Nanoparticles Through Microwave-assisted Acid-catalysis

Microwave-assisted synthetic techniques were used to quickly and reproducibly produce silica nanoparticle sols using an acid catalyst with nanoparticle diameters ranging from 30-250 nm by varying the reaction conditions. Through the selection of a microwave compatible solvent, silicic acid precursor, catalyst, and microwave irradiation time, these microwave-assisted methods were capable of overcoming the previously reported shortcomings associated with synthesis of silica nanoparticles using microwave reactors. The siloxane precursor was hydrolyzed using the acid catalyst, HCl. Acetone, a low-tan &#948; solvent, mediates the condensation reactions and has minimal interaction with the electromagnetic field. Condensation reactions begin when the silicic acid precursor couples with the microwave radiation, leading to silica nanoparticle sol formation. The silica nanoparticles were characterized by dynamic light scattering data and scanning electron microscopy, which show the materials&#39; morphology and size to be dependent on the reaction conditions. Microwave-assisted reactions produce silica nanoparticles with roughened textured surfaces that are atypical for silica sols produced by St&#246;ber&#39;s methods, which have smooth surfaces.

Silica nanoparticles were prepared using acid-catalysis of a siloxane precursor and microwave-assisted synthetic techniques resulting in the controlled growth of nanomaterials ranging from 30-250 nm in diameter. The growth dynamics can be controlled by varying the initial silicic acid concentration, time of the reaction, and temperature of reaction.

Microwave-assisted synthetic techniques were used to quickly and reproducibly produce silica nanoparticle sols using an acid catalyst with nanoparticle ...

The Synthesis of [Sn10(Si(SiMe3)3)4]2- Using a Metastable Sn(I) Halide Solution Synthesized via a Co-condensation Technique

The number of well-characterized metalloid tin clusters, synthesized by applying the disproportionation of a metastable Sn(I) halide in the presence of a sterically demanding ligand, has increased in recent years. The metastable Sn(I) halide is synthesized at&#160;&#34;outer space conditions&#34; via the preparative co-condensation technique. Thereby, the subhalide is synthesized in an oven at high temperatures, around 1,300 &#176;C, and at reduced pressure by the reaction of elemental tin with hydrogen halide gas (e.g., HCl). The subhalide (e.g., SnCl) is trapped within a matrix of an inert solvent, like toluene at -196 &#176;C. Heating the solid matrix to -78 &#176;C gives a metastable solution of the subhalide. The metastable subhalide solution is highly reactive but can be stored at -78 &#176;C for several weeks. On heating the solution to room temperature, a disproportionation reaction occurs, leading to elemental tin and the corresponding dihalide. By applying bulky ligands like Si(SiMe3)3, the intermediate metalloid cluster compounds can be trapped before complete disproportionation to elemental tin. Hence, the reaction of a metastable Sn(I)Cl solution with Li-Si(SiMe3)3 gives [Sn10(Si(SiMe3)3)4]2- 1 as black crystals in high yield. 1 is formed via a complex reaction sequence including salt metathesis, disproportionation, and degradation of larger clusters. Further, 1 can be analyzed by various methods like NMR or single crystal X-ray structure analysis.

The Synthesis of [Sn10SiSiMe334]2- Using a Metastable SnI Halide Solution Synthesized via a Co-condensation Technique

The disproportionation reaction of a metastable Sn(I) chloride solution, obtained via the preparative co-condensation technique, is used for the synthesis of a metalloid tin cluster compound.

A síntese de [Sn<sub&gt; 10</sub&gt; (Si (SiMe<sub&gt; 3</sub&gt;)<sub&gt; 3</sub&gt;)<sub&gt; 4</sub&gt;]<sup&gt; 2</sup<sup&gt; -</sup&gt; Usando um Metastable Sn (I) Solução Halide Sintetizado por meio de uma técnica de co-condensação

The number of well-characterized metalloid tin clusters, synthesized by applying the disproportionation of a metastable Sn(I) halide in the presence of a ...

Synthesis of Cyclic Polymers and Characterization of Their Diffusive Motion in the Melt State at the Single Molecule Level

We demonstrate a method for the synthesis of cyclic polymers and a protocol for characterizing their diffusive motion in a melt state at the single molecule level. An electrostatic self-assembly and covalent fixation (ESA-CF) process is used for the synthesis of the cyclic poly(tetrahydrofuran) (poly(THF)). The diffusive motion of individual cyclic polymer chains in a melt state is visualized using single molecule fluorescence imaging by incorporating a fluorophore unit in the cyclic chains. The diffusive motion of the chains is quantitatively characterized by means of a combination of mean-squared displacement (MSD) analysis and a cumulative distribution function (CDF) analysis. The cyclic polymer exhibits multiple-mode diffusion which is distinct from its linear counterpart. The results demonstrate that the diffusional heterogeneity of polymers that is often hidden behind ensemble averaging can be revealed by the efficient synthesis of the cyclic polymers using the ESA-CF process and the quantitative analysis of the diffusive motion at the single molecule level using the MSD and CDF analyses.

A protocol for the synthesis and characterization of diffusive motion of cyclic polymers at the single molecule level is presented.

Síntese de polímeros cíclicos e Caracterização do seu movimento difusivo no estado fundido na molécula de nível único

We demonstrate a method for the synthesis of cyclic polymers and a protocol for characterizing their diffusive motion in a melt state at the single ...

Electrochemical Impedance Spectroscopy as a Tool for Electrochemical Rate Constant Estimation

Electrochemical impedance spectroscopy (EIS) was used for advanced characterization of organic electroactive compounds along with cyclic voltammetry (CV). In the case of fast reversible electrochemical processes, current is predominantly affected by the rate of diffusion, which is the slowest and limiting stage. EIS is a powerful technique that allows separate analysis of stages of charge transfer that have different AC frequency response. The capability of the method was used to extract the value of charge transfer resistance, which characterizes the rate of charge exchange on the electrode-solution interface. The application of this technique is broad, from biochemistry up to organic electronics. In this work, we are presenting the method of analysis of organic compounds for optoelectronic applications.

Electrochemical impedance spectroscopy (EIS) of species that undergo reversible oxidation or reduction in solution was used for determination of rate constants of oxidation or reduction.

Espectroscopia de impedância eletroquímica como uma ferramenta para estimativa de constante taxa eletroquímica

Electrochemical impedance spectroscopy (EIS) was used for advanced characterization of organic electroactive compounds along with cyclic voltammetry (CV). ...

Determination of Thermodynamic Properties of Alkaline Earth-liquid Metal Alloys Using the Electromotive Force Technique

A novel electrochemical cell based on a CaF2 solid-state electrolyte has been developed to measure the electromotive force (emf) of binary alkaline earth-liquid metal alloys as functions of both composition and temperature in order to acquire thermodynamic data. The cell consists of a chemically stable solid-state CaF2-AF2 electrolyte (where A is the alkaline-earth element such as Ca, Sr, or Ba), with binary A-B alloy (where B is the liquid metal such as Bi or Sb) working electrodes, and a pure A metal reference electrode. Emf data are collected over a temperature range of 723 K to 1,123 K in 25 K increments for multiple alloy compositions per experiment and the results are analyzed to yield activity values, phase transition temperatures, and partial molar entropies/enthalpies for each composition.

This protocol describes the measurement of the electromotive force of alkaline-earth elements in liquid metal alloys at high temperatures (723-1,123 K) to determine their thermodynamic properties, including activity, partial molar entropy, partial molar enthalpy, and phase transition temperatures, over a wide composition range.

Determinação de propriedades termodinâmicas de líquidos alcalinos terrosos de ligas metálicas utilizando a técnica de força eletromotriz

A novel electrochemical cell based on a CaF2 solid-state electrolyte has been developed to measure the electromotive force (emf) of binary alkaline ...

Probing the Structure and Dynamics of Interfacial Water with Scanning Tunneling Microscopy and Spectroscopy

Water/solid interfaces are ubiquitous and play a key role in many environmental, biophysical, and technological processes. Resolving the internal structure and probing the hydrogen-bond (H-bond) dynamics of the water molecules adsorbed on solid surfaces are fundamental issues of water science, which remains a great challenge owing to the light mass and small size of hydrogen. Scanning tunneling microscopy (STM) is a promising tool for attacking these problems, thanks to its capabilities of sub-&#197;ngstr&#246;m spatial resolution, single-bond vibrational sensitivity, and atomic/molecular manipulation. The designed experimental system consists of a Cl-terminated tip and a sample fabricated by dosing water molecules in situ onto the Au(111)-supported NaCl(001) surfaces. The insulating NaCl films electronically decouple the water from the metal substrates, so the intrinsic frontier orbitals of water molecules are preserved. The Cl-tip facilitates the manipulation of the single water molecules, as well as gating the orbitals of water to the proximity of Fermi level (EF) via tip-water coupling. This paper outlines the detailed methods of submolecular resolution imaging, molecular/atomic manipulation, and single-bond vibrational spectroscopy of interfacial water. These studies open up a new route for investigating the H-bonded systems at the atomic scale.

Here, we present a protocol to investigate the structure and dynamics of interfacial water at the atomic scale, in terms of submolecular resolution imaging, molecular manipulation, and single-bond vibrational spectroscopy.

Sondagem da Estrutura e Dinâmica da Água Interfacial com Microscopia de Tunelamento de Varredura e Espectroscopia

Water/solid interfaces are ubiquitous and play a key role in many environmental, biophysical, and technological processes. Resolving the internal ...

Elemental-sensitive Detection of the Chemistry in Batteries through Soft X-ray Absorption Spectroscopy and Resonant Inelastic X-ray Scattering

Energy storage has become more and more a limiting factor of today's sustainable energy applications, including electric vehicles and green electric grid based on volatile solar and wind sources. The pressing demand of developing high-performance electrochemical energy storage solutions, i.e., batteries, relies on both fundamental understanding and practical developments from both the academy and industry. The formidable challenge of developing successful battery technology stems from the different requirements for different energy-storage applications. Energy density, power, stability, safety, and cost parameters all have to be balanced in batteries to meet the requirements of different applications. Therefore, multiple battery technologies based on different materials and mechanisms need to be developed and optimized. Incisive tools that could directly probe the chemical reactions in various battery materials are becoming critical to advance the field beyond its conventional trial-and-error approach. Here, we present detailed protocols for soft X-ray absorption spectroscopy (sXAS), soft X-ray emission spectroscopy (sXES), and resonant inelastic X-ray scattering (RIXS) experiments, which are inherently elemental-sensitive probes of the transition-metal 3d and anion 2p states in battery compounds. We provide the details on the experimental techniques and demonstrations revealing the key chemical states in battery materials through these soft X-ray spectroscopy techniques.

Here, we present a protocol for typical experiments of soft X-ray absorption spectroscopy (sXAS) and resonant inelastic X-ray scattering (RIXS) with applications in battery material studies.

Elemental-sensíveis à deteção da química em baterias através de espectroscopia de absorção de raios-x moles e espalhamento inelástico de raios-x ressonante

Energy storage has become more and more a limiting factor of today's sustainable energy applications, including electric vehicles and green electric grid ...

DNA Origami-Mediated Substrate Nanopatterning of Inorganic Structures for Sensing Applications

Structural DNA nanotechnology provides a viable route for building from the bottom-up using DNA as construction material. The most common DNA nanofabrication technique is called DNA origami, and it allows high-throughput synthesis of accurate and highly versatile structures with nanometer-level precision. Here, it is shown how the spatial information of DNA origami can be transferred to metallic nanostructures by combining the bottom-up DNA origami with the conventionally used top-down lithography approaches. This allows fabrication of billions of tiny nanostructures in one step onto selected substrates. The method is demonstrated using bowtie DNA origami to create metallic bowtie-shaped antenna structures on silicon nitride or sapphire substrates. The method relies on the selective growth of a silicon oxide layer on top of the origami deposition substrate, thus resulting in a patterning mask for following lithographic steps. These nanostructure-equipped surfaces can be further used as molecular sensors (e.g., surface-enhanced Raman spectroscopy (SERS)) and in various other optical applications at the visible wavelength range owing to the small feature sizes (sub-10 nm). The technique can be extended to other materials through methodological modifications; therefore, the resulting optically active surfaces may find use in development of metamaterials and metasurfaces.

Here, we describe a protocol to create discrete and accurate inorganic nanostructures on substrates using DNA origami shapes as guiding templates. The method is demonstrated by creating plasmonic gold bowtie-shaped antennas on a transparent substrate (sapphire).

DNA origami-mediada substrato Nanopatterning de estruturas inorgânicas para aplicações de sensoriamento

Structural DNA nanotechnology provides a viable route for building from the bottom-up using DNA as construction material. The most common DNA ...

Covalent Attachment of Single Molecules for AFM-based Force Spectroscopy

Atomic force microscopy (AFM)-based single molecule force spectroscopy is an ideal tool for investigating the interactions between a single polymer and surfaces. For a true single molecule experiment, covalent attachment of the probe molecule is essential because only then can hundreds of force-extension traces with one and the same single molecule be obtained. Many traces are in turn necessary to prove that a single molecule alone is probed. Additionally, passivation is crucial for preventing unwanted interactions between the single probe molecule and the AFM cantilever tip as well as between the AFM cantilever tip and the underlying surface. The functionalization protocol presented here is reliable and can easily be applied to a variety of polymers. Characteristic single molecule events (i.e., stretches and plateaus) are detected in the force-extension traces. From these events, physical parameters such as stretching force, desorption force and desorption length can be obtained. This is particularly important for the precise investigation of stimuli-responsive systems at the single molecule level. As exemplary systems poly(ethylene glycol) (PEG), poly(N-isopropylacrylamide) (PNiPAM) and polystyrene (PS) are stretched and desorbed from SiOx (for PEG and PNiPAM) and from hydrophobic self-assembled monolayer surfaces (for PS) in aqueous environment.

Covalent attachment of probe molecules to atomic force microscopy (AFM) cantilever tips is an essential technique for the investigation of their physical properties. This allows us to determine the stretching force, desorption force and length of polymers via AFM-based single molecule force spectroscopy with high reproducibility.

Ligação covalente de moléculas únicas para espectroscopia de força baseada em AFM

Atomic force microscopy (AFM)-based single molecule force spectroscopy is an ideal tool for investigating the interactions between a single polymer and ...