I am performing DAB:Ni staining in mouse brain cryosections (adult and neonatal). I get a background black precipitate on my sections. In adults it isn't too much of a problem as it seems to be confined to areas that I am less interested in, however in the neonatal sections that I have just started using the precipitate appears across the whole section.
Does anyone know if it is possible to eliminate this background staining? I have outlined my protocol below
I perform an antigen retrieval step, and wash my sections in PBS. I block in normal serum (have used 2% BSA in the past and bg still appears).
The DAB solution is made from sigma tablets and I filter it after it has been dissolved in PBS.
I have attached a picture to show what the bg looks like.