DMSO dilution vs. inhibitor dissolving; which 1st? - (Dec/06/2009 )

I am culturing macrophages and then introducing an inhibitor after a week of culturing. The inhibitor must be dissolved in DMSO. Do I dissolve in 100% DMSO first and then dilute w/ my cell medium to achieve 0.1% DMSO? Or is the DMSO diluted first and then the inhibitor dissolved?

I'd definitely recommend the first option: first dissolve your inhibitor in DMSO, then dilute (otherwise your inhibitor might never go in solution in the first place).

Are you sure it has to be dissolved in DMSO? If you are talking about a peptide inhibitor, you can try dissolving it in 50% acetonitrile and then diluting it to your working dilution. A 5% concentration of acetonitrile usually does not cause problems.
Otherwise, I would agree with the previous post = first dissolve in 100% DMSO and then dilute to 0.1%, but in our experience if you can not dissolve something in aqueous buffer in the first place it will precipitate in your working dilution sooner or later.

Miha

you first dissolve in 100% dmso (as others have already pointed out).

but...

is the dilution to 0.1% made before adding to the culture (not likely for reasons of solubility) or is that the final concentration of dmso in the culture (very likely)?

mdfenko on Dec 7 2009, 08:14 AM said:

Thanks everyone for the answers. I really appreciate it.