The authors present an interesting method to increase the retention of
radiolabeled nanoparticles for tumor imaging. They took a small
radiolabeled peptide sequence that cleaves at certain junctions in the
presence of furin and subsequently condenses to form a dimer, then
self-assembles into nanoparticles. The key here is that furin is a
protein that's overexpressed in certain cancer cells, so the
radiolabeled nanoparticles would only self-assemble in cancer cells.