[par]

Does anybody know what cosolvent can be used in cell culture systems. for some samples that are hydrophobic and could not be solvend in the aqueous medium what cosolvent or surfactant can be used?

[dayglo]

You should check the literature. There are a lot of studies where they test drugs or labeling systems which are not totally soluble in water. I could name some that in small percentages I think would be okay, but I don't want to mislead you, in case I'm wrong quoting off the top of my head. I would look in journals like ACS Chemical Biology and Nature Chemical Biology.