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Dave,

You can try PicoGreen. It is very bright and remains bright after fixation, however it also stains mitochondrial DNA. I do not know if it can survive paraffin embedding and dewaxing. 

Alexander


Alexander Jurkevich, PhD
Associate Director
Molecular Cytology Core
University of Missouri


-----Original Message-----
From: Confocal Microscopy List [mailto:[log in to unmask]] On Behalf Of Dave Johnston
Sent: Wednesday, February 01, 2017 8:25 AM
To: [log in to unmask]
Subject: fixable, dead cell nuclear counterstain.

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Can anyone recommend a non membrane permiable, fixable, nuclear counterstain, which neither fluoresces far red, nor requires hard UV excitation (so DAPI is out) which can then withstand wax embedding for histology? We have a user who wants to test a novel delivery system into which an aqueous phase dye can be incorporated, the test being that if the delivery system gets into a cell and is processed, the dye will be released and enter the nucleus to bind the DNA and stain the cell. The experiments will be in vivo, hence there is a need to fix and wax embed.

I know that there are membrane impermeant, fixable cytosolic amine reactive dyes which would stain the cell if delivered this way but wondered about a nuclear stain.

There seems relatively little literature on fixable DNA dyes or does one assume that aldehyde based fixation will cross-link any already incorporated dye.

Thanks in advance,

Dave Johnston,
Biomedical Imaging Unit, 
Southampton.