Fig. 4.

Schematic illustration of the different methods for radiolabelling liposomes. (A) Surface radiolabelling: the radionuclide, with or without a chelator, can be linked to the liposomal membrane via a PEG chain or incorporated directly into the lipid bilayer. (B) Intraliposomal radiolabelling: the radionuclide is encapsulated within the aqueous core. Ionophores can be used to transport radionuclides across the bilayer where they can be bound by chelators or drugs inside the liposomes, or radioactive compounds/complexes can passively cross the bilayer and become trapped.