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Brightest nanoparticles shun quantum

1/19/2011 05:40 PM EST
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R_Colin_Johnson
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re: Brightest nanoparticles shun quantum
R_Colin_Johnson   1/19/2011 6:41:38 PM
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Quantum dots used to be the world's brightest nanoparticles, but now Clarkson University has one-upped quantum confinement in favor of encapsulating fluorescent organic nanoparticles inside silicon dioxide. I am sure that quantum-dot researchers will volley back to try and regain the lead. Nevertheless, @NextGenLog I predict that ultra-sensitive detectors using functionalized silica nanoparticles will appear in three years.

pixies
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re: Brightest nanoparticles shun quantum
pixies   1/19/2011 8:36:31 PM
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I did not read the original article, but "brightness" seems to be a poor choice of metric. When comparing two emitters, Quantum Efficiency is usually the proper measure. You can have a emitter with a low quantum efficiency but still make it brighter by cranking up the injection current. I guess what the author was trying to say is that since the nanoparticles were not quantized, the Density of State at the emission energy was higher therefore each particle was capable of emitting more photons.

R_Colin_Johnson
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re: Brightest nanoparticles shun quantum
R_Colin_Johnson   1/19/2011 10:32:10 PM
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Using both together would be a fluorescent nanoparticle whose size is matched to the wavelength of its emission, thus combining quantum confinement with particle fluorescence. Not sure whether such a hybrid is feasible, but I am sure that it is a lot easier to imagine than to do.

R_Colin_Johnson
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re: Brightest nanoparticles shun quantum
R_Colin_Johnson   1/19/2011 10:55:34 PM
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Though experiments can only take us so far, but it sounds like you may be onto something that's worth a try!

wilber_xbox
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re: Brightest nanoparticles shun quantum
wilber_xbox   1/19/2011 11:29:44 PM
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If i understood the news correctly then large number of fluorescent organic molecules are trapped into nanoporous SiO2, which has higher brightness than a quantum dot. Although each organic fluorescent molecules is a quantum dot, nanoporous SiO2 is acting as a medium only to confine all the molecules at one place. So it is not SiO2 which is fluorescent. And the higher brightness is due to the higher number of the organic molecules (quantum dots).

wilber_xbox
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re: Brightest nanoparticles shun quantum
wilber_xbox   1/19/2011 11:38:37 PM
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If i go by the logic that the bigger the size of porous SiO2 nanoparticle the higher the number of fluorescent organic molecules trapped into it, then why the brightness is only 34 times than that of quantum dot? Are they comparing the same size particles and dots or is there any limit on the size of produced SiO2 nanoparticles?

R_Colin_Johnson
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re: Brightest nanoparticles shun quantum
R_Colin_Johnson   1/20/2011 12:03:02 AM
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The researchers started with ultra-bright but micron-sized silica particles in 2007, and since then have been working to downsize them to the nanoscale. At first brightness suffered from the downsizing, but now they are going public because they claim to have succeeded in making ultra-bright, yet very small, fluorescent nanoparticles.

R_Colin_Johnson
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re: Brightest nanoparticles shun quantum
R_Colin_Johnson   1/20/2011 12:20:01 AM
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I checked with the researchers, and they say that the fluorescent dyes inside are not quantum dots, but conventional organic marker-dyes already used in biomedical applications. The reason they can make conventional fluorescent marker-dyes brighter than quantum dots, is that their silicon dioxide shells are porous--thus they can pack more dye into its internal channels. Usually you can't pack the dyes together tightly, because they clump, degrading fluorescence, but by packing them in separate internal channels, the mesoporous silica shells allow more dye per unit area.

Warren3
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re: Brightest nanoparticles shun quantum
Warren3   1/20/2011 1:02:07 AM
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The positive impact from improved sensetivity (smaller number of indicators needed to create a given visual response) should be significant. Size does matter though and even 20nm particles might be too much for some (many?) applications.

R_Colin_Johnson
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re: Brightest nanoparticles shun quantum
R_Colin_Johnson   1/20/2011 2:03:11 AM
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These researchers are not using quantum dots, but instead are using traditional organic fluorescent dyes--but packing then more tightly than is possible without the channels inside their silica shells. I asked them about quantum dots, but they said they could get a wider gamut of colors by using different combinations of colored organic dyes.

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