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Dansyl is listed as having a peak at 700 nm in the table at
http://www.olympusmicro.com/primer/techniques/fluorescence/multiphoton/multi
photonintro.html
<http://www.olympusmicro.com/primer/techniques/fluorescence/multiphoton/mult
iphotonintro.html>

It only has a data point (DN) in the upper of the two graphs.

Molecular Probes 1-photon spectra is at
http://probes.invitrogen.com/servlets/spectra?fileid=113moh
<http://probes.invitrogen.com/servlets/spectra?fileid=113moh>  with the
excitation peak at 334 nm (
http://probes.invitrogen.com/media/spectra/data/113moh.txt
<http://probes.invitrogen.com/media/spectra/data/113moh.txt> ).

Try a few wavelengths with several different objective lenses: Mary
Dickinson's JBO 2003 article (Pubmed ID 12880336) shows big differences
across excitation wavelengths for different objective lenses. The MP
cross-section is nice to know, but the objective lens transmission spectrum
matters.

Can you see your stained specimen with the 340 nm exciter of a Fura-2 filter
set? The 1-photon spectra of Dansyl resembles Fura-2 w/calcium.



Best wishes,


George


-----Original Message-----
From: Miller, Jason [mailto:[log in to unmask]]
Sent: Thursday, August 04, 2005 9:16 PM
To: [log in to unmask]
Subject: multiphoton excitation of monodansyl cadaverine (MDC)


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Hi all-

I have looked rather high and low for any sources on multiphoton excitation
of monodansyl cadaverine (MDC) but haven't found any (I still haven't found
a good common resource for MP cross-sections of common fluorophores- does
anyone know of one?). I have a SP Mai Tai NLO system and have tried looking
for optimal excitation of MDC (we're trying to evaluate putative markers of
autophagy) across the laser's tunable spectrum (710-990 nm) but really only
get some very weak emission at 740 nm and even less at all other excitation
wavelengths. Is MDC known to be a poor multiphoton fluorophore? It doesn't
seem like I'm getting rapid bleach rates- just weak absorption.

Sincere thanks-
Jason Miller
UCSF

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