Tumor-targeting, superparamagnetic polymeric vesicles as highly efficient MRI contrast probes

Tumor-targeting polymeric vesicles were prepared using a mixture of two amphiphilic block copolymers, namely, folate-poly(ethylene glycol)-poly(D,L-lactide) (folate-PEG-PDLLA) and NH2-PEG-PDLLA. The copolymers were synthesized through sequential anionic polymerization in a well-controlled manner. Hydrophilic superparamagnetic iron oxide nanoparticles (SPIONs) were encapsulated in the aqueous core of the polymeric vesicles. Similar to the hydrophilic SPIONs, the SPION-loaded polymeric vesicles exhibited the superparamagnetic property. Moreover, the SPION-loaded polymeric vesicles demonstrated a higher r2/r1 value than a commercially available T2 agent, Resovist®, which can be attributed to the high SPION loading level and the SPION clustering effect in the aqueous core of the vesicles. Thus, tumor-targeting, SPION-loaded polymer vesicles can serve as highly efficient T2 contrast probes for cancer diagnosis and treatment.