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Does anyone have experience with microscope imaging of very low IRDye 800 signals in 
tissue sections? Particularly I am interested in two things:

1) What equipment you are using successfully.

2) Photostability issues.

We are using the following setup:

Mercury arc lamp, SP-106 filter set from Chroma, Hamamatsu Orca BT-1024G on a Zeiss 
Axioimager, 63X 1.4 NA oil immersion lens. Sections are either paraffin or frozen 10 to 
20 µm thick.

We have also tried, Xenon arc, halogen cranked up to 12V, 41009 filter set from Chroma. 
None of these helped much. I have checked for and removed IR filters at every accessible 
place in the lightpath. I am sure we are putting a lot of light into the specimen because 
you can see it very brightly even though the center wavelength of the excitation filter is 
740 nm. Also, we can detect the autofluorescent signal, just nothing specific.

Scanning the tissue sections on a Licor gel scanner gives a detectable signal. The control 
sections are negative on the scanner.

Hoping someone can help.

Kate Luby-Phelps