Briefly, first, the water-in-oil emulsion is shaped by
brief sonication of a two-phase system, containing
phospholipids in organic solvent such as isopropyl ether
or diethyl ether or a mixture of isopropyl ether and
chloroform with aqueous buffer. The organic solvents
are detached under reduced pressure, resulting in the
creation of a viscous gel. The liposomes are shaped
when residual solvent is detached during continued rotary
evaporation under reduced pressure. With this
method, high encapsulation efficiency up to 65% can be
obtained in a medium of low ionic strength for example
0.01 M NaCl. The method has been used to encapsulate
small, large, and macromolecules. The main drawback of
the technique is the contact of the materials to be
encapsulated to organic solvents and to brief periods of
sonication. These conditions may possibly result in the
breakage of DNA strands or the denaturation of some
proteins [32]. Modified reverse phase evaporation
method was presented by Handa et al., and the main
benefit of the method is that the liposomes had high encapsulation
efficiency (about 80%) [33].