Posted by
Maria Calvo-2 on
URL: http://confocal-microscopy-list.275.s1.nabble.com/LaVision-TriM-multiphoton-microscope-tp4962077p4975414.html
Hi,
Answering the question from Colin Rickman, I found in the archives from
2006 an answer from Mike Ignatius to a similar question (he talks about
blinking).
My question was also related to that mail, what types of mounting media
are compatible to Quantum dots?
Thank you!
Maria Calvo
Find below the mail from the archives:
Dear Laurent,
Caution, Vendor's somewhat torn response.
We sell both products and have of course compared them. (I will assume
since you call them QDots that you are using our product.) You asked
about size and blinking.
Size:
The QDot nanocrystal conjugates are indeed larger than organic dyes.
Depending on the color (the redder the bigger) they can reach 10 to 15
nm's and with full IgGs decorating them (2-4 on average) even larger. So
like DPI for printers, larger is not better for high resolution ICC.
However, we only see real big differences when we deconvolve the images,
since this is all sub-resolution.
However, the packing density is less. So while QDot nanocrystals are
brighter in the vial, on your prep they are more likely equivalent in
terms of brightness to Alexa dyes - less dots per unit area when
compared to dyes.
A cautionary note: Please do not use Prolong or Prolong Gold or anything
but cytoseal or PBS glycerol type mountants, such as our SlowFade gold
for mounting QDot Nanocrystals. They will disappear overnight. We have
an ever growing "n" value on this behavior. Our PIS stipulates this with
the product.)
Blinking:
The blinking is certainly apparent to the eye and thus to fast cameras.
Integrating over time avoids this concern - merely reduce your lamp
intensity to help out. We see the blinking with individual dots the
most, while ensembles tend to average out. It is worth noting that some
have found the blinking a nice confirmation that they are looking at a
nanocrystals, not background or organic dyes.
When to use Organic dyes when to use Nanocrystals?
This is where we are sometimes torn. The narrow full width half maximums
of Qdot nanocrystals, as you describe, indeed allow more colors. The
photostability, while terrific for live cell work, rare event detection
and repeated scanning of confocal stacks, is less of a boon in wide
field, single scan experiments. Especially with good dyes and antifades.
So when you need photostability or more colors, nanocrystals are worth
considering.
Mike Ignatius
Molecular Probes/Invitrogen.
------------------------------------------------------------------------
*From:* Confocal Microscopy List [mailto:
[hidden email]]
*On Behalf Of *laurent barbe
*Sent:* Thursday, July 27, 2006 12:49 AM
*To:*
[hidden email]
*Subject:* Qdot vs Alexa
Search the CONFOCAL archive at
http://listserv.acsu.buffalo.edu/cgi-bin/wa?S1=confocalDear users,
I have a quite broad, general question for users who experienced these 2
dyes. I’m doing colocalization study with 3d stacks, which means quite
long exposure. I am doing 4 color imaging, which made me try Qdots to be
able to fit all probes trying to reduce overlapping.
Obviously Qdots are more stable for long exposure than Alexa dyes but
I’d like to have user’s feedbacks from people who compared both.
I also read many times that Qdots blink, even thouh I haven’t faced this
problem yet, as well as Qdots are more ‘bulky’ after conjugation
compared to Alexa.
Any thoughts and feedbacks would be appreciated.
Thanks
Laurent
______________________________________________
Laurent Barbe, Research Fellow
Royal University of Technology (KTH)
School of Nanobiotechnology - Dpt of Biotechnology
Roslagstullsbacken 21, 10601 STOCKHOLM
SWEDEN
Tel: (+46) 855378832
Fax: (+46) 855378323
--
___________________________________
Dra. Maria Calvo
Unitat de Microscòpia Confocal
Serveis Cientificotècnics-C.Casanova
Facultat de Medicina
Universitat de Barcelona- IDIBAPS
C/ Casanova 143
Barcelona 08036
Tel: 34 934037159/39930
Fax: 34 934039946
E-mail:
[hidden email]
___________________________________