Potential usage of thermosensitive liposomes for macromolecule delivery

Since transient swelling during phase transition of liposomes with hyper-osmotic internal aqueous phase may cause permeation of large molecules through the lipid bilayer, this type of liposomes can be useful for delivering macromolecules. In fact, thermosensitive liposomes containing an internal solution with osmotic pressure 2-fold higher than the physiologic level and sized through 200-nm pore, released encapsulated macromolecules such as dextran (M_r 144000) effectively when they were incubated at 40-42°C. These liposomes were stable in the presence of serum compared to the liposomes with internal osmotic pressure more than 3-fold higher than the physiologic level.