Liu G, Dou S, Cheng D, Leif J, Rusckowski M, Streeter PR, Schultz LD, Hnatowich D, Greiner D. Human islet cell MORF/cMORF pretargeting in a xenogeneic murine transplant model. Mol Pharm. 2011 Mar 1. [Epub ahead of print]

Antibody with conjugated Morpholino binds to a cell marker in-vivo, second Morpholino brings Tc radiolabel and binds first Morpholino.

Advantage: this technique minimizes exposure of organism to radiation as tag is delivered.  Antibodies take a long time to clear the serum.  Pretargeting with the Morpholino-labeled antibody can be done slowly and unbound antibody has time to clear.  Once the radiolabeled complementary Morpholino is added, it clears the plasma relatively quickly but has high affinity for its complementary oligo, so the radiation sticks where it is needed and disappears quickly elsewhere.