Agradecemos ao Prof JP Spatz (Departamento de Química Biofísica, da Universidade de Heidelberg e do Departamento de Novos Materiais e Biosystems, do Instituto Max Planck para Sistemas Inteligentes, Stuttgart) por seu apoio gentil. O apoio financeiro do Max-Planck-Gesellschaft ea Deutsche Forschungsgemeinschaft (DFG SFB/TR79 a EAC-A.) São também reconheceu muito.

1. Síntese de 11-Mercaptoundecanoyl-N-hidroxissuccinimida (NHS-MU) <ol><li> Adicionar gota a gota uma solução de 500 mg de N-hidroxissuccinimida e 30 mg de 4 - (dimetilamino) piridina em 10 ml de acetona (aa) a 1 g de ácido 11-mercaptoundecanóico em 40 ml de diclorometano (aa), à temperatura ambiente (RT). </li><li> Arrefecer a reacção até 0 ° C e adicionar gota a gota 1,1 g de N, N &#39;-diciclohexilcarbodiimida em 10 ml de diclorometano (sob atmosfera de azoto). Manter a reacção a baixa temperatura durante 1 hora e, em seguida, agita-se à TA durante a noite. </li><li> Filtrar o precipitado e secá-lo, sob pressão reduzida. Purifica-se o produto por cromatografia flash com o benzeno de petróleo e acetato de etilo (aa) em uma proporção de 1:1. </li></ol> 2. Preparação de Layers Ouro Homogêneos <ol><li> Lamelas de vidro limpos com toalhetes de precisão e sonicar las durante 5 minutos em uma solução contendo uma mistura de 1:1 de acetato de etilo (pa) e metanol (pa). Rinse substratos com metanol e secar sob fluxo de nitrogênio. </li><li> Colocar os substratos limpos no dispositivo de revestimento por pulverização. Evacuar a câmara. Retirar a camada de óxido de cromo superior da meta de cromo por pulverização catódica para 60 seg. Coloque as amostras debaixo da viga e revesti-los com uma camada de crómio de 10 nm, seguido por revestimento com uma camada de ouro de 40 nm de metal. </li></ol> 3. Imobilização de superfície de BMP-2 <ol><li> Dissolve-MU-NHS em N, N-dimethlyformamide (DMF) a uma concentração final de cerca de 1 mM e incubar substratos de ouro na solução de MU-NHS à TA durante 4 h sob atmosfera de azoto. </li><li> Sonicar superfícies em DMF durante 2 minutos, enxaguar com DMF e MeOH e secar sob fluxo de azoto. </li><li> Prepara-se uma solução estoque de rhBMP-2 em HCl 4 mM estéril com uma concentração de 100 ug / ml (de loja alíquotas a -80 ° C). Para diluições de trabalho (3,5 ug / ml), dilui-se a solução de reserva em PBS / NaCl (PBS contendo 1 M de NaCl) e umdjust para pH 8,5, imediatamente antes de usar. </li><li> Incubar superfícies funcionalizadas MU-NHS na solução de trabalho de rhBMP-2, a 4 ° C durante a noite. Retirar o sobrenadante da incubação. Sonicar superfícies em PBS / NaCl durante 2 min e lavagem 3 x com PBS estéril / NaCl. </li></ol> 4. Superfície Caracterização <ol><li> Para bloquear a adsorção inespecífica do anticorpo, incubar as superfícies com BSA 5% (w / v) em solução de PBS durante 1 hora à temperatura ambiente, seguido por incubação com um anticorpo anti-BMP-2 do anticorpo (a 1:100 em 1% (w / v ) solução de BSA / PBS) durante 1 hora à temperatura ambiente. Lave as superfícies duas vezes com PBS e sonicado por 30 seg. </li><li> Incubar substratos com anticorpo secundário conjugado com HRP (1:1000 em 1% (w v) / solução de BSA / PBS) durante 30 min à temperatura ambiente, em seguida, lavar duas vezes com PBS. </li><li> Use Ampliflu ensaio Vermelho para medir a atividade enzimática HRP a 570 nm com um leitor de placas. </li></ol> 5. Análise da atividade biológica <ol><li> Semente 1 x 10 5 rato mioblastos C2C12 por poço em 6-bem plmados em meio de crescimento, que consiste em um DMEM de glicose elevada contendo piruvato suplementado com 10% FBS, 1% de penicilina / estreptomicina e incubar durante 24 horas a 37 ° C / 5% de CO 2. </li><li> Starve células em DMEM isento de soro durante 3-5 horas antes da semeadura sobre as superfícies decoradas com imobilizada BMP-2. </li><li> Para efeitos de investigação da indução de sinalização de curto prazo, substituir o meio por 200 ul de DMEM fresco isento de soro e colocar os imobilizadas BMP-2 superfícies superiores das células. A superfície deve ser tratado com pinças de ponta fina para evitar arranhões. </li><li> Remova suavemente superfícies e aspirar o meio com uma pipeta, lavar as células duas vezes com PBS. Continuar a análise das respostas das células. </li><li> Para a análise da actividade biológica de longo prazo, de células de placa sobre as superfícies e cultura los a 37 ° C / 5% de CO 2 em condições de soro baixo (2% de FBS) durante seis dias. </li></ol>

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Neste protocolo, descrevem a preparação de superfícies funcionalizadas com bioactivo rhBMP-2. Esta abordagem compreende dois passos: 1) a formação inicial de uma monocamada auto-montagem (SAM) de um ligante bifuncional sobre a superfície de ouro, 2) de imobilização covalente da proteína de rhBMP-2. Em trabalhos anteriores, que validou a ligação efectiva do ligante bifuncional e o factor de crescimento, e demonstraram que a superfície imobilizada-rhBMP-2 mantém a sua actividade biológica 19. A bi...

A proteína morfogenética óssea 2 (BMP-2) é um membro do factor de crescimento transformante (TGF-β) familiar e actua como indutor da formação de novo osso, bem como regulador de vários tecidos durante o desenvolvimento embrionário e adulto homeostase 1-3. Cada monómero do biologicamente activo homodimérica proteína BMP-2 contém um motivo &quot;nó de cisteína&quot;, que é altamente conservada em todos os quatro BMPs. Seis dos sete resíduos de cisteína que formam ligações dissulfureto intramoleculares que estabilizam cada monómero, enquanto a sétima cisteína está envolvido na dimerização, formando uma ligação intramolecular entre os dois monómeros de 5,6. Este nó de cisteína altamente conservado define a estrutura tridimensional da proteína BMP-2 e determina as suas propriedades únicas, tais como a resistência ao calor, desnaturantes e ácida de pH 7-9. BMP-2 liga-se a serina / treonina-quinase de receptores transmembranares, induzindo deste modo a transdução de sinal <sup&gt; 10-12. Dependendo do modo de oligomerização do receptor, diferentes vias de sinalização são activados: uma cascata de sinalização Smad-independente leva a indução de fosfatase alcalina através de sinalização de p38, enquanto que uma via dependente de Smad activado pelos resultados da fosforilação do receptor no complexo de Smad translocação nuclear e activação da transcrição de genes-alvo específicos, tais como o inibidor da diferenciação (Id), 12-14. No osso, a BMP-2 induz a diferenciação de células estaminais mesenquimais em osteoblastos, estimulando, assim, a cicatrização e formação de novo de osso. Actualmente, expressa de forma recombinante BMP-2 é aplicada clinicamente para melhorar a cicatrização de sítios fracturados. Uma estratégia comum na engenharia de tecido ósseo é a utilização de factores de crescimento injectáveis, que é menos invasiva em relação aos sistemas de distribuição local. No entanto, estudos in vivo e aplicações clínicas têm demonstrado que a sua meia-vida biológica curta, loc inespecíficazação e rápida de domiciliação de BMP-2 pode levar a vários problemas locais, ectópica e sistêmicas 15. Assim, para obter uma apresentação eficaz, o aprisionamento ou imobilização de BMP-2 no interior de ou sobre materiais é necessário para o seu local de entrega e mantida no local alvo. Entrega sustentada pode ser conseguida com métodos de retenção não covalentes, tais como a retenção física, adsorção ou complexação de iões 16. No entanto, sabe-se que a adsorção não específica de proteínas para as superfícies podem resulta em desnaturação das moléculas de 17. Para a ligação de fatores de crescimento covalente, diferentes tipos de suportes foram desenvolvidos ao longo da última década. A utilização de moléculas de ligação bifuncionais, que se destinam a grupos amino ou carboxilo da proteína, por exemplo, é um tipo de abordagem que não requer, necessariamente, a modificação de proteínas para alcançar a sua imobilização. De facto, enquanto que a modificação de proteínas oferece a vantagem de controlar a orientação da proteína,a introdução dos domínios artificiais, as etiquetas e cadeias peptídicas específicas do local pode alterar a actividade biológica dos factores de crescimento 17. Assim, para contornar a desnaturação devido à interacção com o material de apoio, as superfícies podem ser previamente funcionalizados, por exemplo, com uma monocamada auto-montada (SAM) de uma molécula de ligação, seguido de acoplamento do fator desejado 18. Usámos uma abordagem baseada no SAM para imobilizar covalentemente BMP-2 para uma superfície de direccionamento dos seus resíduos de amina livre e têm mostrado que a proteína imobilizada retém a sua actividade biológica tanto a curto e longo prazo 19. Este protocolo fornece uma maneira simples e eficiente para entregar BMP-2 em células para estudos in vitro sobre os mecanismos que ocorrem na membrana celular e regulam a sinalização intracelular responsável pela sinalização osteogênica.

<table border="1">
	<tbody>
		<tr>
			<td>Name of Material/ Equipment</td>
			<td>Company</td>
			<td>Catalog Number</td>
			<td>Comments/Description</td>
		</tr>
		<tr>
			<td>N-hydroxysuccinimide</td>
			<td>Sigma-Aldrich</td>
			<td>130672</td>
			<td></td>
		</tr>
		<tr>
			<td>4-(dimethylamino)pyridin</td>
			<td>Sigma-Aldrich</td>
			<td>522805</td>
			<td></td>
		</tr>
		<tr>
			<td>Acetone</td>
			<td>AppliChem</td>
			<td>A2282</td>
			<td></td>
		</tr>
		<tr>
			<td>11-mercaptoundecanoic acid</td>
			<td>Sigma-Aldrich</td>
			<td>674427</td>
			<td></td>
		</tr>
		<tr>
			<td>Dichlormethane</td>
			<td>Merck</td>
			<td>106050</td>
			<td></td>
		</tr>
		<tr>
			<td>N,N&#39;-dicyclohexylcarbodiimide</td>
			<td>Sigma-Aldrich</td>
			<td>D80002</td>
			<td></td>
		</tr>
		<tr>
			<td>Petroleum benzene</td>
			<td>Merck</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Glass coverslips</td>
			<td>Carl Roth</td>
			<td>M 875</td>
			<td></td>
		</tr>
		<tr>
			<td>Ethylacetate</td>
			<td>AppliChem</td>
			<td>A3550</td>
			<td></td>
		</tr>
		<tr>
			<td>Methanol</td>
			<td>Carl Roth</td>
			<td>4627</td>
			<td></td>
		</tr>
		<tr>
			<td>N,N-dimethylformamide</td>
			<td>Carl Roth</td>
			<td>T921</td>
			<td></td>
		</tr>
		<tr>
			<td>rhBMP-2</td>
			<td>R&#38;D Systems</td>
			<td>355-BM</td>
			<td>Carrier-free; expressed in E.coli</td>
		</tr>
		<tr>
			<td>PBS</td>
			<td>PAA</td>
			<td>H15-002</td>
			<td></td>
		</tr>
		<tr>
			<td>NaCl</td>
			<td>Carl Roth</td>
			<td>HN00.2</td>
			<td></td>
		</tr>
		<tr>
			<td>Poly(dimethyl siloxane) (PDMS)</td>
			<td>Dow Corning</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Sylgard 184 silicone elastomer kit</td>
			<td>Dow Corning</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Anti-rhBMP-2</td>
			<td>Sigma</td>
			<td>B9553</td>
			<td></td>
		</tr>
		<tr>
			<td>Goat anti-mouse IgG-HRP</td>
			<td>Santa Cruz</td>
			<td>sc-2005</td>
			<td>Secondary antibody</td>
		</tr>
		<tr>
			<td>Ampliflu Red assay</td>
			<td>Sigma</td>
			<td>90101</td>
			<td></td>
		</tr>
		<tr>
			<td>Dulbecco&#39;s Modified Eagle Medium (DMEM) (1x), liquid</td>
			<td>Gibco</td>
			<td>41966</td>
			<td>High glucose</td>
		</tr>
		<tr>
			<td>Fetal Bovine Serum (FBS)</td>
			<td>Sigma</td>
			<td>F7524</td>
			<td>Sterile filtered, cell culture tested</td>
		</tr>
		<tr>
			<td>Pen/Strep</td>
			<td>Gibco</td>
			<td>15140</td>
			<td></td>
		</tr>
		<tr>
			<td>Trypsin 0.05% (1x) with EDTA 4Na</td>
			<td>Gibco</td>
			<td>25300</td>
			<td></td>
		</tr>
		<tr>
			<td>Glycine (0.1 M)</td>
			<td>Riedel-de Ha&#235;n</td>
			<td>33226</td>
			<td></td>
		</tr>
		<tr>
			<td>IGEPAL CA-630 (1%)</td>
			<td>Sigma</td>
			<td>I8896</td>
			<td>Lysis buffer (ALP assay)19</td>
		</tr>
		<tr>
			<td>Magnesium chloride (MgCl2)(1 mM)</td>
			<td>Carl Roth</td>
			<td>HNO3.2</td>
			<td></td>
		</tr>
		<tr>
			<td>Zinc chloride (ZnCl2) (1 mM)</td>
			<td>Carl Roth</td>
			<td>3533.1</td>
			<td></td>
		</tr>
		<tr>
			<td>p-nitrophenylphosphate (pNPP)</td>
			<td>Sigma</td>
			<td>S0942</td>
			<td>Phosphatase substrate</td>
		</tr>
		<tr>
			<td>Anti-mysin heavy chain (MHC)</td>
			<td>Developmental Studies Hybridoma Bank, University of Iowa</td>
			<td>MF20</td>
			<td>Monoclonal antibody</td>
		</tr>
		<tr>
			<td>Alexa Fluor 488 Goat anti-mouse IgG</td>
			<td>Invitrogen</td>
			<td>A11001</td>
			<td></td>
		</tr>
		<tr>
			<td>DAPI</td>
			<td>Sigma</td>
			<td>D9542</td>
			<td></td>
		</tr>
		<tr>
			<td></td>
			<td></td>
			<td></td>
			<td>Equipment</td>
		</tr>
		<tr>
			<td>Ultrsonic bath (Sonorex Super RK 102H), Frequency 35 kHz</td>
			<td>BANDELIN electronic GmbH &#38; Co. KG</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>MED 020 Sputtercoating system</td>
			<td>BAL-TEC AG</td>
			<td></td>
			<td>Coating conditions 
			Cr: 120 mA, 1.3 x 10-2 mbar, 30 sec 
			Au: 60 mA, 5.0 x 10-2 mbar, 45 sec</td>
		</tr>
		<tr>
			<td>Tecan Infinite M200 Plate reader</td>
			<td>Tecan</td>
			<td></td>
			<td></td>
		</tr>
	</tbody>
</table>

covalent binding of bmp-2 on surfaces using a self-assembled monolayer approach

A proteína morfogenética óssea 2 (BMP-2) é um factor de crescimento incorporados na matriz extracelular do tecido ósseo. BMP-2 atua como gatilho da diferenciação de células mesenquimais em osteoblastos, estimulando, assim, a cura e formação de osso novo. O uso clínico de humano recombinante BMP-2 (rhBMP-2) em conjunto com andaimes suscitou controvérsias recentes, com base no modo de apresentação e a quantidade a ser entregue. O protocolo aqui apresentado fornece um meio simples e eficaz para entregar a BMP-2 para os estudos in vitro em células. Descrevemos como para formar uma monocamada auto-montada que consiste num ligante heterobifuncional, e mostram o passo de ligação posterior para obter a imobilização covalente de rhBMP-2. Com esta abordagem, é possível conseguir uma apresentação sustentada de BMP-2, enquanto que a manutenção da actividade biológica da proteína. Na verdade, a superfície de imobilização de BMP-2 permite investigações orientadas, impedindo anúncios inespecíficasorption, enquanto reduz a quantidade de factor de crescimento e, mais notavelmente, dificultando a libertação não controlada da superfície. Ambos os eventos de sinalização de curto e longo prazo são desencadeadas por BMP-2 está a ter lugar quando as células são expostas a superfícies que apresentam covalentemente imobilizada a rhBMP-2, tornando esta abordagem adequada para estudos in vitro sobre as respostas celulares a BMP-2 de estimulação.

Em nossa configuração, o ouro foi escolhido como excipiente, uma vez que fornece um sistema biologicamente inespecífica, mas quimicamente ajustável. Além disso, a aplicação de camadas auto-montagem implica muitas vantagens: SAM adsorver espontaneamente através dos seus grupos &quot;cabeça-&quot; sobre metais e monocamadas de formulário com poucos defeitos, enquanto os grupos terminais funcionais pode ser modificado. Assim, eles proporcionam uma plataforma para adaptar as propriedades da interface de um modo ai...

Watch this Scientific Journal Video about Covalent Binding of BMP-2 on Surfaces Using a Self-assembled Monolayer Approach at JoVE.com

Covalent Binding of BMP-2 on Surfaces Using a Self-assembled Monolayer Approach

Descreve-se um método para realizar a imobilização eficiente de BMP-2 em superfícies. A nossa abordagem é baseada na formação de uma monocamada auto-montada para alcançar a ligação da BMP-2 por meio dos seus resíduos de amina livres covalente. Este método é uma ferramenta útil para o estudo de sinalização na membrana celular.

A ligação covalente de BMP-2 em superfícies com uma monocamada auto-montada Abordagem

Bone morphogenetic protein 2 (BMP-2) is a growth factor embedded in the extracellular matrix of bone tissue. BMP-2 acts as trigger of mesenchymal cell ...

covalent-binding-bmp-2-on-surfaces-using-self-assembled-monolayer

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Organic Chemistry

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Unit 1

Covalent Bonding and Structure

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13.8K visualizações.  University of Heidelberg.  Descreve-se um método para realizar a imobilização eficiente de BMP-2 em superfícies. A nossa abordagem é baseada na formação de uma monocamada auto-montada para alcançar a ligação da BMP-2 por meio dos seus resíduos de amina livres covalente. Este método é uma ferramenta útil para o estudo de sinalização na membrana celular. 

Vídeo: Covalent Binding of BMP-2 on Surfaces Using a Self-assembled Monolayer Approach

Stabilizing Hepatocellular Phenotype Using Optimized Synthetic Surfaces

Currently, one of the major limitations in cell biology is maintaining differentiated cell phenotype. Biological matrices are commonly used for culturing and maintaining primary and pluripotent stem cell derived hepatocytes. While biological matrices are useful, they permit short term culture of hepatocytes, limiting their widespread application. We have attempted to overcome the limitations using a synthetic polymer coating. Polymers represent one of the broadest classes of biomaterials and possess a wide range of mechanical, physical and chemical properties, which can be fine-tuned for purpose. Importantly, such materials can be scaled to quality assured standards and display batch-to-batch consistency. This is essential if cells are to be expanded for high through-put screening in the pharmaceutical testing industry or for cellular based therapy. Polyurethanes (PUs) are one group of materials that have shown promise in cell culture. Our recent progress in optimizing a polyurethane coated surface, for long-term culture of human hepatocytes displaying stable phenotype, is presented and discussed.

This article will focus on developing polymer coated surfaces for long-term, stable culture of stem cell derived human hepatocytes.

Estabilização hepatocelular Fenótipo Usando superfícies sintéticas otimizados

Currently, one of the major limitations in cell biology is maintaining differentiated cell phenotype. Biological matrices are commonly used for culturing ...

Química

An Inverse Analysis Approach to the Characterization of Chemical Transport in Paints

The ability to directly characterize chemical transport and interactions that occur within a material (i.e., subsurface dynamics) is a vital component in understanding contaminant mass transport and the ability to decontaminate materials. If a material is contaminated, over time, the transport of highly toxic chemicals (such as chemical warfare agent species) out of the material can result in vapor exposure or transfer to the skin, which can result in percutaneous exposure to personnel who interact with the material. Due to the high toxicity of chemical warfare agents, the release of trace chemical quantities is of significant concern. Mapping subsurface concentration distribution and transport characteristics of absorbed agents enables exposure hazards to be assessed in untested conditions. Furthermore, these tools can be used to characterize subsurface reaction dynamics to ultimately design improved decontaminants or decontamination procedures. To achieve this goal, an inverse analysis mass transport modeling approach was developed that utilizes time-resolved mass spectroscopy measurements of vapor emission from contaminated paint coatings as the input parameter for calculation of subsurface concentration profiles. Details are provided on sample preparation, including contaminant and material handling, the application of mass spectrometry for the measurement of emitted contaminant vapor, and the implementation of inverse analysis using a physics-based diffusion model to determine transport properties of live chemical warfare agents including distilled mustard (HD) and the nerve agent VX.

In this paper, a procedure for quantifying the mass transport parameters of chemicals in various materials is presented. This process involves employing an inverse-analysis based diffusion model to vapor emission profiles recorded by real-time, mass spectrometry in high vacuum.

Uma abordagem de análise inversa à caracterização dos Transportes Química em Tintas

The ability to directly characterize chemical transport and interactions that occur within a material (i.e., subsurface dynamics) is a vital component in ...

Facile Preparation of Internally Self-assembled Lipid Particles Stabilized by Carbon Nanotubes

We present a facile method to prepare nanostructured lipid particles stabilized by carbon nanotubes (CNTs). Single-walled (pristine) and multi-walled (functionalized) CNTs are used as stabilizers to produce Pickering type oil-in-water (O/W) emulsions. Lipids namely, Dimodan U and Phytantriol are used as emulsifiers, which in excess water self-assemble into the bicontinuous cubic Pn3m phase. This highly viscous phase is fragmented into smaller particles using a probe ultrasonicator in presence of conventional surfactant stabilizers or CNTs as done here. Initially, the CNTs (powder form) are dispersed in water followed by further ultrasonication with the molten lipid to form the final emulsion. During this process the CNTs get coated with lipid molecules, which in turn are presumed to surround the lipid droplets to form a particulate emulsion that is stable for months. The average size of CNT-stabilized nanostructured lipid particles is in the submicron range, which compares well with the particles stabilized using conventional surfactants. Small angle X-ray scattering data confirms the retention of the original Pn3m cubic phase in the CNT-stabilized lipid dispersions as compared to the pure lipid phase (bulk state). Blue shift and lowering of the intensities in characteristic G and G&#39; bands of CNTs observed in Raman spectroscopy characterize the interaction between CNT surface and lipid molecules. These results suggest that the interactions between the CNTs and lipids are responsible for their mutual stabilization in aqueous solutions. As the concentrations of CNTs employed for stabilization are very low and lipid molecules are able to functionalize the CNTs, the toxicity of CNTs is expected to be insignificant while their biocompatibility is greatly enhanced. Hence the present approach finds a great potential in various biomedical applications, for instance, for developing hybrid nanocarrier systems for the delivery of multiple functional molecules as in combination therapy or polytherapy.

We report on a smart application of carbon nanotubes for kinetic stabilization of lipid particles that contain self-assembled nanostructures in their cores. The preparation of lipid particles requires rather low concentrations of carbon nanotubes permitting their use in biomedical applications such as drug delivery.

Preparação Facile da Internamente auto-montados Lipid partículas estabilizada por nanotubos de carbono

We present a facile method to prepare nanostructured lipid particles stabilized by carbon nanotubes (CNTs). Single-walled (pristine) and multi-walled ...

Highly Stable, Functional Hairy Nanoparticles and Biopolymers from Wood Fibers: Towards Sustainable Nanotechnology

Nanoparticles, as one of the key materials in nanotechnology and nanomedicine, have gained significant importance during the past decade. While metal-based nanoparticles are associated with synthetic and environmental hassles, cellulose introduces a green, sustainable alternative for nanoparticle synthesis. Here, we present the chemical synthesis and separation procedures to produce new classes of hairy nanoparticles (bearing both amorphous and crystalline regions) and biopolymers based on wood fibers. Through periodate oxidation of soft wood pulp, the glucose ring of cellulose is opened at the C2-C3 bond to form 2,3-dialdehyde groups. Further heating of the partially oxidized fibers (e.g., T = 80 &#176;C) results in three products, namely fibrous oxidized cellulose, sterically stabilized nanocrystalline cellulose (SNCC), and dissolved dialdehyde modified cellulose (DAMC), which are well separated by intermittent centrifugation and co-solvent addition. The partially oxidized fibers (without heating) were used as a highly reactive intermediate to react with chlorite for converting almost all aldehyde to carboxyl groups. Co-solvent precipitation and centrifugation resulted in electrosterically stabilized nanocrystalline cellulose (ENCC) and dicarboxylated cellulose (DCC). The aldehyde content of SNCC and consequently surface charge of ENCC (carboxyl content) were precisely controlled by controlling the periodate oxidation reaction time, resulting in highly stable nanoparticles bearing more than 7 mmol functional groups per gram of nanoparticles (e.g., as compared to conventional NCC bearing &#60;&#60; 1 mmol functional group/g). Atomic force microscopy (AFM), transmission electron microscopy (TEM), and scanning electron microscopy (SEM) attested to the rod-like morphology. Conductometric titration, Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR), dynamic light scattering (DLS), electrokinetic-sonic-amplitude (ESA) and acoustic attenuation spectroscopy shed light on the superior properties of these nanomaterials.

Synthesis schemes to prepare highly stable wood fiber-based hairy nanoparticles and functional cellulose-based biopolymers have been detailed.

Altamente estável, funcional Hairy Nanopartículas e Biopolímeros de fibras de madeira: Rumo a nanotecnologia Sustentável

Nanoparticles, as one of the key materials in nanotechnology and nanomedicine, have gained significant importance during the past decade. While ...

Microfluidic-based Synthesis of Covalent Organic Frameworks (COFs): A Tool for Continuous Production of COF Fibers and Direct Printing on a Surface

Covalent Organic Frameworks (COFs) are a class of porous covalent materials which are frequently synthesized as unprocessable crystalline powders. The first COF was reported in 2005 with much effort centered on the establishment of new synthetic routes for its preparation. To date, most available synthetic methods for COF synthesis are based on bulk mixing under solvothermal conditions. Therefore, there is increasing interest in developing systematic protocols for COF synthesis that provide for fine control over reaction conditions and improve COF processability on surfaces, which is essential for their use in practical applications. Herein, we present a novel microfluidic-based method for COF synthesis where the reaction between two constituent building blocks, 1,3,5-benzenetricarbaldehyde (BTCA) and 1,3,5-tris(4-aminophenyl)benzene (TAPB), takes place under controlled diffusion conditions and at room temperature. Using such an approach yields sponge-like, crystalline fibers of a COF material, hereafter called MF-COF. The mechanical properties of MF-COF and the dynamic nature of the approach allow the continuous production of MF-COF fibers and their direct printing onto surfaces. The general method opens new potential applications requiring advanced printing of 2D or 3D COF structures on flexible or rigid surfaces.

Microfluidic-based Synthesis of Covalent Organic Frameworks COFs: A Tool for Continuous Production of COF Fibers and Direct Printing on a Surface

We present a novel microfluidic-based method for synthesis of covalent organic frameworks (COFs). We demonstrate how this approach can be used to produce continuous COF fibers, and also 2D or 3D COF structures on surfaces.

Síntese com base em microfluídicas de estruturas orgânicas covalentes (COFs): uma ferramenta para produção contínua de fibras COF e impressão direta em uma superfície

Covalent Organic Frameworks (COFs) are a class of porous covalent materials which are frequently synthesized as unprocessable crystalline powders. The ...

Light-driven Molecular Motors on Surfaces for Single Molecular Imaging

The design and synthesis of a synthetic system that aims for the direct visualization of a synthetic rotary motor at the single molecule level on surfaces are demonstrated. This work requires careful design, considerable synthetic effort, and proper analysis. The rotary motion of the molecular motor in solution is shown by 1H NMR and UV-vis absorption spectroscopy techniques. In addition, the method to graft the motor onto an amine-coated quartz is described. This method helps to gain more insight into molecular machines.

The manuscript describes how to synthesize and graft a molecular motor on surfaces for single molecular imaging.

Motores moleculares orientado a luz em superfícies para única imagem Molecular

The design and synthesis of a synthetic system that aims for the direct visualization of a synthetic rotary motor at the single molecule level on surfaces ...

Analysis of Complex Molecules and Their Reactions on Surfaces by Means of Cluster-Induced Desorption/Ionization Mass Spectrometry

Desorption/Ionization Induced by Neutral SO2 Clusters (DINeC) is employed as a very soft and efficient desorption/ionization technique for mass spectrometry (MS) of complex molecules and their reactions on surfaces. DINeC is based on a beam of SO2 clusters impacting on the sample surface at low cluster energy. During cluster-surface impact, some of the surface molecules are desorbed and ionized via dissolvation in the impacting cluster; as a result of this dissolvation-mediated desorption mechanism, low cluster energy is sufficient and the desorption process is extremely soft. Both surface adsorbates and molecules of which the surface is composed of can be analyzed. Clear and fragmentation-free spectra from complex molecules such as peptides and proteins are obtained. DINeC does not require any special sample preparation, in particular no matrix has to be applied. The method yields quantitative information on the composition of the samples; molecules at a surface coverage as low as 0.1 % of a monolayer can be detected. Surface reactions such as H/D exchange or thermal decomposition can be observed in real-time and the kinetics of the reactions can be deduced. Using a pulsed nozzle for cluster beam generation, DINeC can be efficiently combined with ion trap mass spectrometry. The matrix-free and soft nature of the DINeC process in combination with the MSn capabilities of the ion trap allows for very detailed and unambiguous analysis of the chemical composition of complex organic samples and organic adsorbates on surfaces.

Neutral SO2 clusters of low kinetic energy (&#60; 0.8 eV/constituent) are used to desorb complex surface molecules such as peptides or lipids for further analysis by means of mass spectrometry using an ion trap mass spectrometer. No special sample preparation is required, and real-time observation of reactions is possible.

Análise de Moléculas Complexas e Suas Reações em Superfícies por meio da espectrometria de desormetria/desonização induzida por cluster

Desorption/Ionization Induced by Neutral SO2 Clusters (DINeC) is employed as a very soft and efficient desorption/ionization technique for mass ...

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 ...

Synthesis of pH Dependent Pyrazole, Imidazole, and Isoindolone Dipyrrinone Fluorophores using a Claisen-Schmidt Condensation Approach

Methine-bridged conjugated bicyclic aromatic compounds are common constituents of a range of biologically relevant molecules such as porphyrins, dipyrrinones, and pharmaceuticals. Additionally, restricted rotation of these systems often results in highly to moderately fluorescent systems as observed in 3H,5H-dipyrrolo[1,2-c:2',1'-f]pyrimidin-3-ones, xanthoglows, pyrroloindolizinedione analogs, BODIPY analogs, and the phenolic and imidazolinone ring systems of Green Fluorescent Protein (GFP). This manuscript describes an inexpensive and operationally simple method of performing a Claisen-Schmidt condensation to generate a series of fluorescent pH dependent pyrazole/imidazole/isoindolone dipyrrinone analogs. While the methodology illustrates the synthesis of dipyrrinone analogs, it can be translated to produce a wide range of conjugated bicyclic aromatic compounds. The Claisen-Schmidt condensation reaction utilized in this method is limited in scope to nucleophiles and electrophiles that are enolizable under basic conditions (nucleophile component) and non-enolizable aldehydes (electrophile component). Additionally, both the nucleophilic and electrophilic reactants must contain functional groups that will not inadvertently react with hydroxide. Despite these limitations, this methodology offers access to completely novel systems that can be employed as biological or molecular probes.

The Claisen-Schmidt condensation reaction is an important methodology for the generation of methine-bridged conjugated bicyclic aromatic compounds. Through utilizing a base-mediated variant of the aldol reaction, a range of fluorescent and/or biologically relevant molecules can be accessed through a generally inexpensive and operationally simple synthetic approach.

Síntese de pyrazole dependente de pH, Imidazol e Isoindolone Dipyrrinone Fluorophores usando uma Abordagem de Condensação Claisen-Schmidt

Methine-bridged conjugated bicyclic aromatic compounds are common constituents of a range of biologically relevant molecules such as porphyrins, ...

Analysis of Organochlorine Pesticides in a Soil Sample by a Modified QuEChERS Approach Using Ammonium Formate

Currently, the QuEChERS method represents the most widely used sample preparation protocol worldwide for analyzing pesticide residues in a broad variety of matrices both in official and non-official laboratories. The QuEChERS method using ammonium formate has previously proven to be advantageous compared to the original and the two official versions. On the one hand, the simple addition of 0.5 g of ammonium formate per gram of sample is sufficient to induce phase separation and achieve good analytical performance. On the other hand, ammonium formate reduces the need for maintenance in routine analyses. Here, a modified QuEChERS method using ammonium formate was applied for the simultaneous analysis of organochlorine pesticide (OCP) residues in agricultural soil. Specifically, 10 g of the sample was hydrated with 10 mL of water and then extracted with 10 mL of acetonitrile. Next, phase separation was carried out using 5 g of ammonium formate. After centrifugation, the supernatant was subjected to a dispersive solid-phase extraction clean-up step with anhydrous magnesium sulfate, primary-secondary amine, and octadecylsilane. Gas chromatography-mass spectrometry was used as the analytical technique. The QuEChERS method using ammonium formate is demonstrated as a successful alternative for extracting OCP residues from a soil sample.

The present protocol describes the utilization of ammonium formate for phase partitioning in QuEChERS, together with gas chromatography-mass spectrometry, to successfully determine organochlorine pesticide residues in a soil sample.

Análise de pesticidas organoclorados em uma amostra de solo por uma abordagem QuEChERS modificada usando formato de amônio

Currently, the QuEChERS method represents the most widely used sample preparation protocol worldwide for analyzing pesticide residues in a broad variety ...