Preparation of PFPE-Based Polymeric Nanoparticles via Polymerization-Induced Self-Assembly as Contrast Agents for 19F MRI

Fluorine-19magnetic resonance imaging (F-19 MRI) probeshave received considerable research interest as imaging contrast agents(CAs), but they remain neglected and underutilized due to the limitedfluorine content or poor performance of fluorinated tracers. Here,we present polymeric nanoparticles (NPs) as F-19 MRI CAswith a simple synthesis method and promising imaging performance.First, hydrophilic random copolymers were synthesized from oligo-(ethyleneglycol) methyl ether acrylate and perfluoropolyether methacrylateby reversible addition-fragmentation chain transfer (RAFT) polymerization.The optimal fluorine content, polymer concentration, and cytotoxicityas F-19 MRI CAs were investigated in detail. Then, the optimalcopolymer was selected as the macromolecular chain transfer agent,and the chain extension was performed with 2-(perfluorooctyl ethylmethacrylate). Subsequently, the NPs with different morphologies,such as ellipsoidal, spherical nanoparticles and vesicles, were preparedin situ by the RAFT-mediated polymerization-induced self-assemblymethod. In addition, the F-19 MRI signal and cytotoxicitystudies further confirmed that these polymeric NPs are nontoxic andhave great potential as promising F-19 MRI CAs for biologicalapplications.