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Dossier : les secrets de la couleur | Futura-Sciences

Dossier : les secrets de la couleur | Futura-Sciences | fluorescence | Scoop.it

Découvrez le dossier La couleur dans tous ses éclats. Un tour d'horizon sur la couleur, omniprésente dans la nature et dans notre culture. Vision des couleurs, nuances, teintes, fluorescence et luminescence... Le secret de la couleur !


Via Moguy Watt
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DNA and quantum dots: All that glitters is not gold

DNA and quantum dots: All that glitters is not gold | fluorescence | Scoop.it
A NIST team has shown that by bringing gold nanoparticles close to the dots and using a DNA template to control the distances, the intensity of a quantum dot's fluorescence can be predictably increased or decreased.

Via Luís Bastos
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Luís Bastos's curator insight, January 25, 2013 11:18 AM

A team of researchers at the National Institute of Standards and Technology (NIST) has shown that by bringing gold nanoparticles close to the dots and using a DNA template to control the distances, the intensity of a quantum dot's fluorescence can be predictably increased or decreased.* This breakthrough opens a potential path to using quantum dots as a component in better photodetectors, chemical sensors and nanoscale lasers.

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Video: Creating Transient Cell Membrane Pores Using a Standard Inkjet Printer

Video: Creating Transient Cell Membrane Pores Using a Standard Inkjet Printer | fluorescence | Scoop.it

"Bioprinting has a wide range of applications and significance, including tissue engineering, direct cell application therapies, and biosensor microfabrication.1-10 Recently, thermal inkjet printing has also been used for gene transfection.8,9 The thermal inkjet printing process was shown to temporarily disrupt the cell membranes without affecting cell viability. The transient pores in the membrane can be used to introduce molecules, which would otherwise be too large to pass through the membrane, into the cell cytoplasm.8,9,11
The application being demonstrated here is the use of thermal inkjet printing for the incorporation of fluorescently labeled g-actin monomers into cells. The advantage of using thermal ink-jet printing to inject molecules into cells is that the technique is relatively benign to cells.8, 12 Cell viability after printing has been shown to be similar to standard cell plating methods1,8. In addition, inkjet printing can process thousands of cells in minutes, which is much faster than manual microinjection. The pores created by printing have been shown to close within about two hours. However, there is a limit to the size of the pore created (~10 nm) with this printing technique, which limits the technique to injecting cells with small proteins and/or particles. 8,9,11
A standard HP DeskJet 500 printer was modified to allow for cell printing.3, 5, 8 The cover of the printer was removed and the paper feed mechanism was bypassed using a mechanical lever. A stage was created to allow for placement of microscope slides and coverslips directly under the print head. Ink cartridges were opened, the ink was removed and they were cleaned prior to use with cells. The printing pattern was created using standard drawing software, which then controlled the printer through a simple print command. 3T3 fibroblasts were grown to confluence, trypsinized, and then resuspended into phosphate buffered saline with soluble fluorescently labeled g-actin monomers. The cell suspension was pipetted into the ink cartridge and lines of cells were printed onto glass microscope cover slips. The live cells were imaged using fluorescence microscopy and actin was found throughout the cytoplasm. Incorporation of fluorescent actin into the cell allows for imaging of short-time cytoskeletal dynamics and is useful for a wide range of applications.13-15..."


Via Gerd Moe-Behrens
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Francisco J. Menéndez González's curator insight, April 10, 2013 3:37 AM

cómo convertir una simple impresora en una 3D Bioprinter....¿Dónde podré comprar los cartuchos?¿podré imprimir desde un word?. No estamos tan lejos.......

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A flexible, transparent gesture sensor for touch-free, transparent user interfaces

A flexible, transparent gesture sensor for touch-free, transparent user interfaces | fluorescence | Scoop.it

A new method of capturing images based on a flat, flexible, transparent, and potentially disposable polymer sheet has been developed by a team of researchers at Johannes Kepler University Linz in Austria.

 

The new imager, which resembles a flexible plastic film, uses fluorescent particles to capture incoming light and channel a portion of it to an array of sensors framing the sheet. With no electronics or internal components, the imager’s simple design makes it ideal for a new breed of imaging technologies, including user interface devices that can respond to gestures (touch not required).

 

“To our knowledge, we are the first to present an image sensor that is fully transparent – no integrated microstructures, such as circuits – and is flexible and scalable at the same time,” says team leader Oliver Bimber.

 

The sensor is based on a polymer film known as a luminescent concentrator (LC). It is suffused with tiny fluorescent particles that absorb a very specific wavelength (blue light for example) and then reemit it at a longer wavelength (green light for example). Some of the reemitted fluorescent light is scattered out of the imager, but a portion of it travels throughout the interior of the film to the outer edges, where arrays of optical sensors (similar to 1-D pinhole cameras) capture the light.

 

A computer then combines the signals to create a gray-scale image. “With fluorescence, a portion of the light that is reemitted actually stays inside the film,” says Bimber. “This is the basic principle of our sensor.”

 

For the luminescent concentrator to work as an imager, Bimber and his colleagues had to determine precisely where light was falling across the entire surface of the film. This was the major technical challenge because the polymer sheet cannot be divided into individual pixels like the CCD camera inside a smartphone. Instead, fluorescent light from all points across its surface travels to all the edge sensors.

 

The solution came from the phenomenon of light attenuation, or dimming, as it travels through the polymer. The longer it travels, the dimmer it becomes. So by measuring the relative brightness of light reaching the sensor array, it was possible to calculate where the light entered the film.

 

The main application the researchers envision for this new technology is in touch-free, transparent user interfaces that could seamlessly overlay a television or other display technology. This would give computer operators or video-game players full gesture control without the need for cameras or other external motion-tracking devices.


Via Dr. Stefan Gruenwald
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Genetics & Evolution

Genetics & Evolution | fluorescence | Scoop.it

Behold the green-glowing eel! And it's one popular in sushi! Scientists have decoded protein the first protein ever found that generates fluorescence in a vertebrate -- and it's unlike any biological fluorescent molecule ever seen before.


Via Ursula Sola de Hinestrosa
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Les scientifiques découvrent la clé de la fluorescence verte pour le nano-assemblage

Les scientifiques découvrent la clé de la fluorescence verte pour le nano-assemblage | fluorescence | Scoop.it
L'organisation de la vie requiert des nanostructures fondées sur les protéines, qui à leur tour sont arrangées de façon précise afin de déterminer leurs fonctions spécifiques.
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Un peptide fluorescent ciblé pour le diagnostic précoce de l ... - Journal International de Médecine (Inscription)

Un peptide fluorescent ciblé pour le diagnostic précoce de l ...
Journal International de Médecine (Inscription)
Il apparait chaque année dans le monde 480 000 nouveaux cas de cancer de l'œsophage, fatals dans près de 85 % des cas.
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PHOTOS. Un arbre fluorescent pour remplacer les éclairages de rue - Le Huffington Post

PHOTOS. Un arbre fluorescent pour remplacer les éclairages de rue
Le Huffington Post
Une manière de remplacer à long-terme les moyens d'éclairages traditionnels et pourquoi pas, dans un futur proche, chaque lampadaire par un arbre fluorescent.
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Des nanocristaux « super-fluorescents » - Techniques de l'Ingénieur

Des nanocristaux « super-fluorescents » - Techniques de l'Ingénieur | fluorescence | Scoop.it

Nanocristaux fluorescents à température cryogénique : des chercheurs ont réussi à neutraliser l’effet Auger et ainsi renforcer la fluorescence.


Via ESPCI Paris
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ESPCI Paris's curator insight, May 22, 2013 5:46 AM

Un  nanocristal 100% fluo ? C’est possible à température cryogénique. Publiés dans Nature Nanotechnology, les travaux des chercheurs de Groupe d’Etude de la Matière Condensée - GEMaC (CNRS / UVSQ) et du Laboratoire de Physique et d’Etude des Matériaux - LPEM (CNRS / ESPCI / UPMC) expliquent comment le contrôle de l’effet Auger annule toute perte de fluorescence.

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Une protéine à la fluorescence inégalée pour illuminer les cellules de l'intérieur

Une protéine à la fluorescence inégalée pour illuminer les cellules de l'intérieur | fluorescence | Scoop.it

Des scientifiques du CNRS, de l'ESRF, du CEA, des Universités Joseph Fourier, d'Amsterdam et d'Oxford ont créé une molécule capable d'éclairer l'intérieur des cellules vivantes avec une lumière turquoise, trois fois plus brillante qu'auparavant. Pour étudier les interactions entre protéines…


Via Serge Meunier
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La fluorescence des scorpions un peu mieux connue

La fluorescence des scorpions un peu mieux connue | fluorescence | Scoop.it
Des chercheurs sont parvenus à résoudre une partie de l'énigme de la fluorescence des scorpions....

Via Bernadette Cassel
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Une nouvelle protéine fluorescente 3 fois plus brillante que les autres

Une nouvelle protéine fluorescente 3 fois plus brillante que les autres | fluorescence | Scoop.it

La fluorescence est couramment utilisée en microscopie pour révéler les mécanismes intracellulaires, notamment les interactions entre protéines. Mais la luminosité émise est parfois trop faible pour étudier des réactions rapides.

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Breaking the DNA-binding code of Ralstonia solanacearum TAL effectors provides new possibilities to generate plant resistance genes against bacterial wilt disease - New Phytologist

(Via T. Lahaye & T. Schreiber) De Lange et al 2013 Ralstonia solanacearum is a devastating bacterial phytopathogen with a broad host range. Ralstonia solanacearum injected effector proteins (Rips) are key to the successful invasion of host plants. We have characterized Brg11(hrpB-regulated 11), the first identified member of a class of Rips with high sequence similarity to the transcription activator-like (TAL) effectors of Xanthomonas spp., collectively termed RipTALs. Fluorescence microscopy of in planta expressed RipTALs showed nuclear localization. Domain swaps between Brg11 and Xanthomonas TAL effector (TALE) AvrBs3 (avirulence protein triggering Bs3 resistance) showed the functional interchangeability of DNA-binding and transcriptional activation domains. PCR was used to determine the sequence of brg11 homologs from strains infecting phylogenetically diverse host plants. Brg11 localizes to the nucleus and activates promoters containing a matching effector-binding element (EBE). Brg11 and homologs preferentially activate promoters containing EBEs with a 5′ terminal guanine, contrasting with the TALE preference for a 5′ thymine. Brg11 and other RipTALs probably promote disease through the transcriptional activation of host genes. Brg11 and the majority of homologs identified in this study were shown to activate similar or identical target sequences, in contrast to TALEs, which generally show highly diverse target preferences. This information provides new options for the engineering of plants resistant to R. solanacearum.


Via dromius
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En vidéo : la réponse des globules blancs à une attaque laser

En vidéo : la réponse des globules blancs à une attaque laser | fluorescence | Scoop.it
L'édition 2012 du concours Nikon Small World in Motion a été marquée par la fluorescence, puisque les trois lauréats ont su l'exploiter pour réaliser leurs vidéos. La séquence gagnante dévoile la réponse d'un système immunitaire à une attaque laser.
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La fluorescence, un signe de bonne santé chez les coraux

La fluorescence, un signe de bonne santé chez les coraux | fluorescence | Scoop.it
Certains coraux brillent et cette lumière peut être un outil efficace pour évaluer leur état de santé estiment les chercheurs de la Scripps Institution of Oceanography.

Via Marine Etard, Francis Le Guen
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Stéphane Crémier's curator insight, March 21, 2013 4:20 AM

Beauté et santé intimement liées !

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Une protéine d'anguille bientôt utilisée dans les labos d'analyses sanguines ?

Une protéine d'anguille bientôt utilisée dans les labos d'analyses sanguines ? | fluorescence | Scoop.it
L’unagi, une anguille d’eau douce japonaise, abrite une protéine fluorescente qui pourrait servir de base à de nouveaux tests pour évaluer l’état du foie. 

Via Hubert MESSMER @Zehub on Twitter
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