PET imaging of 64Cu-DOTA-cys-DB-LNP. The DOTA-cys-DB-LNP preparation was radiolabeled with Cu-64 and purified by SEC, yielding two LNP peaks eluting at 16 and 18 minutes. Each preparation was injected into two male NOD/SCID mice bearing LnCap tumors and serial PET imaged over 44 hours. (A) Representative PET imaging of 64Cu-DOTA-cys-DB-LNP peak 1 (16 minutes) over time. Major organs imaged were heart (H), liver (L), and tumor (T). (B) Representative PET imaging of 64Cu-DOTA-cys-DB-LNP peak 2 (18 minutes) over time. At the last time point, computed tomography imaging was performed and overlaid on the PET image. cys-DB, cys-diabody; LNP, lipid nanoparticle; NOD/SCID, non-obese diabetic severe combined immune deficiency; PET, positron emission tomography; SEC, size-exclusion chromatography.