Peptide-functionalized gadolinium liposomes enable HER2-targeted molecular MRI of breast cancer

Targeted molecular magnetic resonance imaging (MRI) of HER2-positive breast cancer remains challenging because of the limited sensitivity of conventional gadolinium-based contrast agents. Herein, we developed multifunctional gadolinium-loaded liposomes functionalized with A9-derived HER2-targeting peptides to achieve selective tumor recognition and enhanced MRI performance. The liposomes exhibited good colloidal stability, enhanced relaxivity compared with free Gd-DTPA, and negligible cytotoxicity. Surface functionalization significantly increased binding to HER2-overexpressing BT-474 cells, with peptide-functionalized liposomes showing the highest affinity. In a preliminary HER2-positive breast cancer xenograft model, peptide-targeted liposomes showed tumor uptake and sustained MRI contrast enhancement, whereas non-functionalized liposomes showed lower tumour contrast enhancement. These preliminary observations support further investigation of peptide-functionalized gadolinium liposomes as a promising molecular MRI platform for HER2-targeted imaging and future theranostic applications.