Rapid 64Cu radiolabeling and in vivo evaluation of DSPE–NODAGA liposomes in a murine mammary tumor model

Understanding the in vivo behavior of nanomedicines is critical for optimizing their therapeutic efficacy and facilitating personalized treatment strategies. In the quest to develop positron emission tomography (PET) methodology for liposome biodistribution studies, we systematically compared three liposome radiolabeling strategies - remote loading of ⁶⁴Cu into liposomes containing the hydrophilic chelator NOTA, membrane labeling using ATSM, and surface labeling with DSPE-NODAGA (phospholipid DSPE conjugated with chelator NODAGA) - to identify an effective method for liposome radiolabeling with ⁶⁴Cu. Our results demonstrated that DSPE-NODAGA incorporated in PEGylated liposomes allows for achieving 100 % radiochemical yield of ⁶⁴Cu at room temperature within just 5 min. Stability studies confirmed liposome integrity and minimal transchelation or dissociation in serum over 24 h, highlighting its suitability for in vivo applications. PET/MR imaging in healthy and tumor-bearing mice revealed prolonged circulation of ⁶⁴Cu-labeled PEGylated liposomes (PL-NODAGA) and significant tumor accumulation, validating DSPE-NODAGA's potential for real-time tracking of liposome delivery. These findings establish the incorporation of DSPE-NODAGA as a robust and adaptable platform for PET-based monitoring of lipidic nanomedicine.