Hello,
I am preparing liposomes with the thin film hydration method. I am working with DPPC,, DSPE-PEG 2000 and Cholesterol in methanol/chloroform (1/2 ratio). The phospholipids weight are about 150 mg in 50 mL flask. The question and problem is that why sometimes I have some white spots (accumulation of phospholipids) in inner surface of the flask during the thin layer and how I can prevent formation of this white spots?
Best regards,
Ali
Dear ali
Unfortunatly i didnt work about liposomes. Im so sorry i couldnt help u.
Mahnaz
Hi Ali,
it happend to me some times with complex lipid mixture in high concentration.
I think 150 mg in a 50 mL flask is a bit much you can try to divide your sample in smaller flask or take a bigger flask whatever works best for you.
another thing I use to do is to play with the solvent mixture, vacuum, or speed of the rotavap.
you'll have to find the right condition for your lipid mixture and even then it is not guaranteed that you'll some white spot now and then.
hope it helped a little
cheers,
Etienne
Dear Etienne,
Thanks for you reply. Actually, I tried with 100 mL flask and I had the same problem. Also, I used to work with only chloroform without methanol. But, sometimes I had it!!
Dear Ali,
1. Why do you think that the white spots are bad? I've never experienced that slight non-homogeneities cause problems later on during hydration.
2. Do you use a new flask? Sometimes the lipid film has another structure at scratches and dents inside.
3. For this composition use only chloroform; you don't need the methanol, and it might cause precipitation of your lipids.
Dear Sven,
Thanks for your reply. I used to work with only chloroform and the spots were bigger!. By adding methanol and sonication, the problem a little bit was fixed. Do you think methanol make a problem during the formation of the thin layer or hydration or even after that?
It might, I don't have too much experience with it, but most lipids are better soluble in chloroform than methanol.
Can you show a picture of these white spots? I still don't think it might not matter for your final product.
During rotavap, take care with the pressure (don't go too low) and choose the appropriate rotation speed to get a good film.
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