I am planning on making working solutions of 17-beta estradiol in DMSO. The drug has been exposed outside of the culture hood. My studies will last up to 7 days, so I am wondering if I should sterilize the drug prior to making the solution in DMSO, or if the DMSO will act as a sterilizer and prevent bacterial growth.
If I do need to sterilize the drug what would be the best method, UV, filtering, etc. I am thinking filtering, but unsure of what size filter.
Thanks.
Hello Joseph, in my opinion I think you should first prepare a stock solution by dissolving 3 mg in 3 mL of 90% ethanol (1 mg/mL concentration). Alternatively, you could make a 100 mM stock of estradiol in 100% ethanol and then subsequently dilute that to 10 mM in 50% ethanol. The 10 mM could then be diluted to 1 mM in water and this is used to make further serial dilutions in "DMSO" after sterilization by filtration (0.2 uM millipore). This way the final concentration of ETOH is less than 0.01% and you do not need an ethanol control. I am wondering why you chose DMSO to prepare working solutions when distilled or de-ionized water would suffice. Note: please store at -20 degC.
I agree with Maurice, I have always use estrogen or tamoxifen in ethanol, not DMSO. However, if you need to use DMSO and your experiments last 7 days you probably won’t need to sterilize your drug. DMSO is very toxic and that is probably going to be enough. The only concern I have is what will happen to the stock solution if stored for long periods.
Thank you for the answers. I will actually use ethanol. The vast majority of papers use ethanol and then dilute down to at least 0.05%. I will create a 1mg/ml solution, filter, and then further dilute until I get my required dosage. Again, thanks for the advice, it was very helpful.
I stored a 100mM stock at -20ºC, but some crystals are formed. Can this cause a decrease in estradiol activity?
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