I have been using the thin-film method to encapsulate drug with DSPE-PEG5K. After obtaining the thin film, I added 2ml PBS for hydration. After a short sonication to help dissolve the thin film, the solution is still turbid. Is this normal? The lipid drug w/w ratios I tried are 10:1 and 20:1. My main question is what does the micelle solution look like after hydration? How can I pass through the 0.2uM filter if solution is turbid, as it may clog the filter?
Micelles are clear colloidal solutions. Turbidity represents unloaded drug particles. Filter it by syringe filter, change the filter if it is clogged.
On the other hand, I don't believe lecithin form micelles in water (or PBS); how much pure is yor lecithin? ... You have to hydrate lipids over this temperature to form liposomes. ... question "What can I do against liposome precipitation after sonication? ... if you have mixed micelles lipid-surfactant your solution should be clear
my experience with phospholipid based suspensions is that the solution turns milky after re-hydration. I used DSPE-PEG-2000 as an emulsifying agent, so I am not sure whether DSPE-PEG alone can form micelles, but certainly in the presence of phosopholipids like DSPC, they form liposomes, when re-hydrated above lipid transition temperature. The final solution is milky white, which resemble the pictures you have shared.
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