Small and bright quantum dots

[Niklas Lorén]

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Dear all,

I am looking for stable and bright quantum dots in the size range 3 to 20 nm. We have laser lines accessible in the range 456 nm to 635 nm. I would be happy for any advice about where to find such quantum dots (or other very bright particles) in that size range.

Best regards
Niklas Lorén

[Jürgen Schmied]

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Commercial Post

Dear Niklas,

please have a look at GATTA-Beads from GATTAquant. www.gattabeads.com
GATTA-Beads are a new type of fluorescent bead and offer several advantages, especially in the size-range 10-20 nm.
GATTA-Beads are:
- very homogenous in size and brightness
- the beads are very bright. Despite the diameter of only 23 nm they are comparable with 40 nm conventional beads
- they can be labeled with all sorts of organic dyes, e.g. Alexa, ATTO, Cy dyes

Please let me know if you have any further questions.

Best regards,
Jürgen Schmied
CEO - GATTAquant

-----Ursprüngliche Nachricht-----
Von: Confocal Microscopy List [mailto:[hidden email]] Im Auftrag von Niklas Lor én
Gesendet: Dienstag, 2. Mai 2017 18:42
An: [hidden email]
Betreff: Small and bright quantum dots

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Dear all,

I am looking for stable and bright quantum dots in the size range 3 to 20 nm. We have laser lines accessible in the range 456 nm to 635 nm. I would be happy for any advice about where to find such quantum dots (or other very bright particles) in that size range.

Best regards
Niklas Lorén

[George McNamara]

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Hi Niklas,

consider BB515 (Brilliant Blue) or BV480 (Brilliant Violet) ...
spectrumviewer shows there is also a BB700.

https://www.bdbiosciences.com/us/applications/research/multicolor-flow/m/745795/sampledata/bluelaser

https://www.bdbiosciences.com/us/applications/multicolor/s/brilliantdyes

For Spectrum Viewer, for BV480, set the fluorochrome to BV480 and
excitation to 457 nm (drop down list above graph).

I have not seen an extinction coefficient or quantum yield for either
BB515 or BV480, so will GUESS: E.c. 1,000,000 M-1 cm-1, QY ~0.5. My
guesses are somewhat lower than BV421 specifications, which Biolegend
has online at https://www.biolegend.com/brilliantviolet  (2,500,000 and
0.65).

When using Brilliant's, or ThermoFisher's Super Bright's (currently
2plex, each for 405 nm excitation)

https://www.thermofisher.com/content/dam/LifeTech/global/life-sciences/Cell%20analysis/pdf/Super_Bright_Polymer_Dyes_Flyer_FC08032_1.pdf

the manufacturers each recommend their staining buffers so their
products do not cross-aggregate (ex. BV421 is ok on its own,
co-aggregate with other BVs, BUVs, BBs). This is a whole lot better than
the old Molecular Probes / Invitrogen quantum dots that were massive
aggregates in the tube. If you want to read up on recent "Vivid" QDots, see:

Prost S, Kishen REB, Kluth DC, Bellamy COC (2016) Working with
Commercially Available Quantum Dots for Immunofluorescence on Tissue
Sections. PLoS ONE 11(9): e0163856. doi:10.1371/journal.pone.0163856


best wishes,
George
p.s. the Brilliant's and Super Brights were developed mostly for flow
cytometry. for fluorescence microscopy, a lot higher excitation power,
especially "at the point" of a point scanning confocal microscope, by
default, so you may evaluate lower laser power (457 nm is usually a
relatively weak laser line), and scan speed (I think: faster is better,
carefully adjust detector settings and line or frame summing for best
signal to noise).

On 5/2/2017 11:42 AM, Niklas Lor én wrote:

> *****
> To join, leave or search the confocal microscopy listserv, go to:
> http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
> Post images on http://www.imgur.com and include the link in your posting.
> *****
>
> Dear all,
>
> I am looking for stable and bright quantum dots in the size range 3 to 20 nm. We have laser lines accessible in the range 456 nm to 635 nm. I would be happy for any advice about where to find such quantum dots (or other very bright particles) in that size range.
>
> Best regards
> Niklas Lorén

--


George McNamara, PhD
Houston, TX 77054
[hidden email]
https://www.linkedin.com/in/georgemcnamara
https://works.bepress.com/gmcnamara/75   (may need to use Microsoft Edge or Firefox, rather than Google Chrome)
http://www.ncbi.nlm.nih.gov/myncbi/browse/collection/44962650

[George McNamara]

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more for this thread: small quantum dots (~10 nm) and fluorescent dyes
were found to behave differently than commercial BIG quantum dots in
this paper from Paul Selvin's lab.

I especially like their improvement in affinity of monomeric
streptavidin (page 23):

"The measured koff of mSA-S25R/T48F (mSA-RF) is 37 fold lower compared
to original mSA, i.e. t½ = 402 min, and ~ 5 fold lower than the best
mutant to date, i.e. mSA-S25H (Figure S8c)."

http://biorxiv.org/content/early/2016/12/27/096966

doi:https://doi.org/10.1101/096966


  Super-resolution Imaging of Synaptic and Extra-synaptic Pools of AMPA
  Receptors with Different- sized Fluorescent Probes

Whether AMPA receptors (AMPARs) enter into neuronal synapses, by
exocytosis from an internal pool, or by diffusion from an external
membrane-bound pool, is hotly contested. 3D super-resolution fluorescent
nanoscopy to measure the dynamics and placement of AMPAR is a powerful
method for addressing this issue. However, probe size and accessibility
to tightly packed spaces can be limiting. We have therefore labeled
AMPARs with differently sized fluorophores: small organic fluorescent
dyes (~ 4 nm), small quantum dots (sQD, ~10 nm in diameter), or big
(commercial) quantum dots (bQD, ~ 20 nm in diameter). We then compared
their diffusion rate, trajectories, and placement with respect to a
postsynaptic density (PSD) protein, Homer 1c. Labeled with the small
probes of sQDs or organic fluorophores, we find that AMPARs are located
largely within PSDs (~73-93%), and generally reside in "nanodomains"
with constrained diffusion. In contrast, when labeled with bQDs, only
5-10% of AMPARs are within PSDs. The results can be explained by
relatively free access, or lack thereof, to synaptic clefts of the
AMPARs when labeled with small or big probes, respectively. This implies
that AMPARs primarily enter PSDs soon after their exocytosis and not
from a large diffusive pool of extrasynaptic AMPARs.




On 5/2/2017 11:42 AM, Niklas Lor én wrote:

> *****
> To join, leave or search the confocal microscopy listserv, go to:
> http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
> Post images on http://www.imgur.com and include the link in your posting.
> *****
>
> Dear all,
>
> I am looking for stable and bright quantum dots in the size range 3 to 20 nm. We have laser lines accessible in the range 456 nm to 635 nm. I would be happy for any advice about where to find such quantum dots (or other very bright particles) in that size range.
>
> Best regards
> Niklas Lorén
>

--




George McNamara, PhD
Houston, TX 77054
[hidden email]
https://www.linkedin.com/in/georgemcnamara
https://works.bepress.com/gmcnamara/75/
http://www.ncbi.nlm.nih.gov/myncbi/browse/collection/44962650