Purification of Liposomes—Detergent Removal Methods
Detergents or surfactants are normally used to facilitate the dilution of lipids in organic solvents. After the formation of liposomes, the excess phospholipids and detergents should be removed. There are several methods to remove the detergents from liposomal solutions, as described below:
Dialysis: This is the most common method for removing detergents, and can be accomplished by using conventional dialysis bags, which work on the basis of equilibrium dialysis [46,47]. Currently, some commercial dialysis devices such as Slide-A-Lyzer Dialysis Cassettes are also available.
Absorption: In this method the mixed micelles or the liposome solutions are treated with organic polystyrene beads such as the XAD-2 beads or Bio-beads SM2. This method is efficient in removing the detergents with low critical micellar concentration values.
Gel permeation chromatography: In this method the separation column contains pretreated beads that adsorb amphiphilic lipids. However, the intact liposomes percolate through the interbead spaces.