[Histonet] non-fluorescent tissue marking dyes

[Michael Giacomelli]

I am working on a pathology study involving two photon microscopy of
pathology samples.  For our study we need to be able to mark the
surface aspects of our tissue with dye prior to histology processing
and multiphoton imaging.  Unfortunately, most of the standard tissue
marking dyes we use have extraordinarily strong fluorescence in the
blue/green when excited in the near UV (2 photon wavelength).  This
strong fluorescence then triggers the overcurrent protection on our
detectors if we stray onto the surface aspect.

Are there any tissue marking dyes that are known to survive histology
processing and also generate little or no blue/green fluorescence?
I'm not concerned about yellow/red fluorescence (its filtered out), or
attenuation without fluorescence as we don't generally image the ink
directly, it just sometimes gets in the way.

I've ordered a few dyes for testing based on their composition, but
I'm essentially just guessing because I haven't been able to find much
information.  I suppose not many people need to fluorescent image
inked specimens.

Thanks,
Mike