The development of nanoscale delivery vehicles based on polymeric micelles has attracted attention in the diagnostic and therapeotic applications in biomedicine. To construct a micellar magnetic resonance imaging (MRI) contrast agent (CA) with biocompatibility and targeting specificity, researchers synthesized two types of amphiphilic diblock polymers, mPEG-PG(DOTA(Gd))-b-PCL and FA-PEG-b-PCL, to form mixed micelles by coassembly. Consisting of poly(caprolactone) (PCL) as core and poly(glycerol) (PG) and poly(ethylene glycol) (PEG) as shell, and modified with DOTA(Gd) chelates and folic acid (FA), the nanostructure of the miceller system had the functions of MRI contrast enhancement and tumor targeting.
In addition, the mixed micelles with high r1 relaxivity exhibited negligible cytotoxicity estimated by WST test. According to the in vitro and in vivo MRI experiments, it showed excellent targeting specificity to tumor cells and tissue. Furthermore, after injecting the tumor-bearing mice with the mixed micelles, the signal intensity was enhanced and the prominent positive contrast effect was achieved. In a word, the mixed micelles has the potential to be used for tumor-targeted imaging as T1 MRI CA.