I have tried with chloroform-methanol (2:1 v/v) but the emulsion produced after sonication is not stable. Also, lipids don't dissolve well in pure ethyl ether.
* I used to obtain REVs by, first, dissolving the lipids in 9 mL of ethyl ether (I had no problems to solve them) and, second, adding 3 mL of aqueous medium (aqueous medium to ether volume ratio = 1/3).
* Then probe sonication was applied for 5 minutes to obtain an emulsion. The sample was kept into an ice bath to avoid phospholipid hydrolysis.
* Next, the emulsion is rotoevaporated at 25 ºC at 460 mmHg of pressure and slow rotation. During the process, emulsion collapses and a compact gel mass is formed and later on it becomes fluid again. This takes about 30 minutes.
* After that, 1 mL of the aqueous medium is added and maximum vacuum is applied for about 20 min and high rotation speed to allow ether evaporation.
* The aqueous sample obtained is the diluted with the aqueous medium to the desired final lipid concentration.The final maximum lipid concentration in the aqueous phase should not exceed 50 mg/mL (take this into account in the first step of the method).
The final suspension contains mostly unilamellar big liposomes (depending on the lipid composition also small liposomes can be formed, for example, if there are negatively charged phospholipids) that can be extruded.
Mixture of ethanol / ethyl acetate (3:1v/v) will go good for single or mixture of lipids by REV in liposomal formulation.
Dear all, the following documents deal with Reverse-phase Evaporation Vesicles ( REV). Please feel free to ask me if you don't have access to anyone of them. My Regards
https://www.researchgate.net/publication/321970386_Preparation_of_Drug_Liposomes_by_Reverse-Phase_Evaporation
https://doi.org/10.1080/026520499289220
10.17352/ojpp.000007
Hi;
First dissolve the phospholipids in an organic solvent such as diethyl ether or isopropyl ether or in chloroform:isopropyl ether 1:1 mixture and add the aqueous phase containing the hydrophilic molecules.
With my best regards
thank you all for your advices. Ramon Barnadas-Rodríguez what kind of phospholipids do you use? I am using DSPC as major component but can't get it dissolved in ether. I have also tried other solvents but none of them generates stable emulsions (phase separation in a few minutes)
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