*****
To join, leave or search the confocal microscopy listserv, go to:
http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
*****

Hi Matiar

I tried Q Dots on formalin fixed, human brain slices a few years ago without a lot of success. We tried both conjugated secondaries and strep linked dots but like you found penetration an issue. We also got high background sometimes although there did not seem to be any pattern to when this appeared or didn't. We got some hot spots where penetration seemed much higher and I suspect they may have been areas where the tissue was damaged or torn allowing them more room to enter

We had some success on paraffin embedded sections. In the end we gave up on trying and stuck with the tried and true Alexa and Cy dyes we were working with.

Thanks

Ray



-----Original Message-----
From: Confocal Microscopy List [mailto:[log in to unmask]] On Behalf Of Matiar Jafari
Sent: Wednesday, 6 June 2012 12:04 p.m.
To: [log in to unmask]
Subject: Quantum dot (Qdot) penetration in brain slices and fluorophore recommendation

*****
To join, leave or search the confocal microscopy listserv, go to:
http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
*****

Dear ListServ,

We recently purchased some Qdots (Life Technologies) to do some secondary
antibody labeling as their Qdot 625 fell really nicely into our emission
filters range  (624 filter / 40 bandpass), however we only get at best 12
um of penetration cumulatively (6 um front of slice and 6 um back of
slice).  I was wondering if anyone here could comment on the penetration
and if they have any comments on how to get better results.  We've even
tried longer incubation, greater concentration of permeabilization reagent,
and longer permeabilization reagent incubation times all to no avail.

Secondly, I was wondering if anyone could recommend a secondary fluorophore
that has a relatively high two photon action cross section, with good
penetration (at least through 25 um of brain tissue), and that fits well
into our emission filter's range (624/40).

Thank You
-------
Matiar Jafari