Hi,
I am using C2C12 cells. I need to treat them with dexamethasone. I would like to know which is the best solvent to dissolve dexamethasone so that it is not toxic to the cells? I am using dex from Sigma
Sigma says methanol, but it is surely toxic.
You can try ethanol, DMSO and DMF (dimethylformamide).
https://www.caymanchem.com/pdfs/11015.pdf
Solubility in ethanol should be comparable to that of methanol (25 mg/mL).
In addition, Sigma recommends:
" Dilute 1 mg/ml stock solution 1:50 with sterile media and store frozen in working aliquots to avoid repeated freeze-thaw. "
This means you prepare an initial stock at 25 mg/mL in ethanol (volatile) or DMSO (not volatile), then dilute parts of that to 1 mg/mL and then dilute it further with sterile medium at a ratio of 1:50, split in aliquots and store off.
Overall, I recommend DMSO over ethanol. You prepare a high conc. stock and then split them in very small liquots (20-30 uL per tubes). DMSO freezes below 0 C, which is good for storage.
Nai-Kei Wong Thank you very much for your answer but eventually we are now dissolving dex in ethanol. DMSO seems to be very toxic to the cells that I am using. They are behaving better with dex in ethanol.
Hello,
The problem with ethanol is that it is volatile. Over time, it will slowly escape from your tubes (a fraction becomes vapor. Once you opens a tube, you lose that). Thus, your concentrations may become uncertain, after long storage.
You are right, that DMSO may have unexpected effects on certain cell types -- leading to death or differentiation.
So it seems ethanol is a solution of some kind for short term.
Good luck on the experiments.
Nai-Kei Wong Thank you very much for such a useful tip! I did not realise this with ethanol. You are right that it cannot be frozen in ethanol. I have prepared aliquots after dissolving dex in ethanol and it does not get frozen. Could you please tell me how long can dex in ethanol be stored before its concentrations may start changing during evaporation?
Nai-Kei Wong Hi....I am still waiting for your answer. How long can dex in ethanol be stored?
Hello, I would suggest 0.5 to 1 year, if the stock is prepared in ethanol and stored at low temperature. Try to use parafilm to seal off the caps of the tubes or container holding the stock solution (to reduce the rate of ethanol escaping as vapor). The freezing point of ethanol is -114.1C. So the stock may not freeze even at -80C in a freezer. Good luck on the exp.!
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