Hi!
I have to dilute my drug (powder) in 100%DMSO. I need to have atleast 3 serial dilutions in 100% DMSO before the final dilution (0.1% dmso) in the media.
the question is should I filter the highest concentration ( in DMSO) or the last one in the media?
The final dilution will have only 1ul of the drug/dmso and Im scared that I lose it after filteration. Can you recommend a good filter?
We have celloluse acetate surfactant free 0.2 in the lab. I am not sure if I can use that for DMSO.
Hello,
Why do you want to filter the solution?
If your drug is completely soluble in DMSO, or if you don't want to make a supersaturated solution, I think you don't need to filter it. Just do "up-and-down" step properly and make sure there is no sediment.
If your drug is not fully soluble in DMSO, you should not filter first dilution (highest concentration). In this case, the amount of drug that should be transferred to the second dilution, would be less than what you want.
Thank you for the reply. I want to filter to avoid possible infection. I have weighed the powder outside of cell lab but the dmso is sterile
Ok. Got it.
If you want to know about drug waste during filteration, you can measure your solution absorbance easily. If the absorbance before filteration is equal to the absorbance after filteration, so it could be concluded that you don't waste the drug.
There is another way too.
If your drug is not sensitive to UV light, put the powder under UV lamp for sterilization.
So you would not need to filter the solution.
wow! how can I make sure its not sensitive to UV light? never heard if this
You could search about it on databases such as PubChem.
Most drugs are "not" sensitive. Specially in power form. Covalent bonds are too strong to be destroyed by UV light.
Mostly, ultraviolet light may cause the formation of hydrogen bonds between different parts of a drug molecule or cause the conversion of the drug into optical isomers. As I remember it mostly occurs in solution form. That's why I said to put the drug "powder" under ultraviolet light, because in this case there is no solvent! And solids are more resistant to UV light than liquids.
Hello Kimia Hosseini
You should dilute your drug powder in 100% DMSO and filter sterilize using 0.2um filter. Filter sterilization of the drug solution in 100% DMSO should be done using nylon or PTFE membrane filters as these are DMSO compatible.
You may refer to the link below for the syringe filters solvent compatibility chart.
https://www.restek.com/row/technical-literature-library/articles/syringe-filters-solvent-compatibility-chart/
Best.
But isn't 100%DMSO enough to kill any possible life form in the solution?
Personally, I wouldn't filter out of fear of not knowing the actual concentration of my drug.
Thanks everyone. I think I will avoid filtering. My supervisor also believes it is very unlikely to see infection growing in 100% DMSO.
Thank you so much for your suggestions
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