FCS and Protein assay - (Jun/02/2009 )
I am using drugs dissolved in DMSO in Caco-2 FCS-free media but I have been told that my drugs are coming out of solution because I have not added any FCS. However I have avoided using serum media because I need to quantify proteins in the cell supernatant using Bradford assay. Is there a way I can account for the FCS in the media when measuring supernatant protein? I am using 5% FCS.
5% FCS will very likely swamp out you being able to detect any secreted proteins. I would be surprised if your drugs are coming out of solution because there is no FCS, more likely is that they are not very soluble in water.
Thanks for your reply. Yes the drugs I am using are very hydrophobic and polar with lots of benzene rings. They readily dissolve in 100% DMSO (which is what I have dissolved them in). I was just told yesterday by a former PhD student that she got the drugs to stay in solution by adding a small % of FCS plus warming the drugs at 37C before transferring to the tissue culture plates with media. I thought the former was a little strange but at this stage I am willing to try anything! I am also going to reduce the concentration of drugs from 50 to 30 uM but I doubt this will have a huge effect on solubility!
Try dissolving them in dimethyl fomamide, it may mean that they stay in solution better.