Background fluorescence problem

Posted by simon walker (BI)-2 on
URL: http://confocal-microscopy-list.275.s1.nabble.com/Background-fluorescence-problem-tp7579031.html

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Dear List,
We are imaging very weakly fluorescent live cells (expressing GFP) on a wide-
field system and having issues with a source of background fluorescence.  
When we look at our cells under epi-illumination we see a rapid drop in a weak
background signal (not where the cells are) that fully recovers over a ~10 s
period after the illumination light is switched off.  Our experiments require the
use of DMEM as the imaging medium and this is the likely cause of problem.  It
appears that something in the medium is sticking to the coverglass.  It's not
phenol red as the effect is seen with both phenol red-containing and phenol-
red-free DMEM.  Does anyone know what else it could be?  Has anyone else
seen anything similar?  We're wondering if it could be riboflavin which is in the
DMEM we're using.  Would this stick to glass?

I've seen that Life Technologies now market a substance that allegedly
surpresses background fluorescence in DMEM:
http://products.invitrogen.com/ivgn/product/R37603
Has anyone tried this?  Does anyone know how it works?

Thanks,
Simon