I have a collection of phospholipids (DOPC, DSPE-PEG) and cholestorel that I mix together to synthesize liposomes. Normally I recieve the lipids aliquotted dissolved in chloroform in the correct molar ratio to synthesize lipsomes. I store the lipids at -80 degrees C, and at time of use I thaw them, dry them, hydrate them with PBS and extrude them.
However, the last batch of lipids I got came shipped in separate aliquots, so I need to mix them together before use. My question is if I re-aliquot all of the lipids into one time use batches for liposome synthesis, can I re-freeze them all until time of use? Or will this freeze/thaw cycle significantly degrade the lipids?
I personally use lipid stocks stored at -20°C, they can be warmed up to 4°C many times while being stable (checked by NMR and MS). Not entirely sure about -80°C storage though - actually Avanti recommends to not store lipid solutions in organic solvents below -30°C unless they are in sealed glass ampoules. You can check out their storage recommendations here: https://avantilipids.com/tech-support/storage-handling-of-lipids
These lipids can be stored at -20 C in liquid form and used many times. Freeze thaw cycles are not required in my opinion. For storage after liposomal formulation, the main issue is lipid transition temperature and the liposomes should be stored below lipid transition temperatures.
please follow this link, https://avantilipids.com/tech-support/storage-handling-of-lipids .
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