Synthesis of 19F MRI Nanotracers by Dispersion Polymerization- Induced Self-Assembly of N-(2,2,2-Trifluoroethyl)acrylamide in Water

19F magnetic resonance imaging (MRI) using fluoropolymer tracers has recently emerged as a promising, non-invasive diagnostic tool in modern medicine. However, despite its potential, 19F MRI remains overlooked and underused due to the limited availability or unfavorable properties of fluorinated tracers. Herein, we report a straightforward synthetic route to highly fluorinated 19F MRI nanotracers via aqueous dispersion polymer-ization-induced self-assembly of a water-soluble fluorinated monomer. A polyethylene glycol-based macromolecular chain-transfer agent was extended by RAFT-mediated N-(2,2,2-trifluoroethyl)acrylamide (TFEAM) polymerization in water, providing fluorine-rich self-assembled nanoparticles in a single step. The resulting nanoparticles had different morphologies and sizes ranging from 60 to 220 nm. After optimizing their structure to maximize the magnetic relaxation of the fluorinated core, we obtained a strong 19F NMR/MRI signal in an aqueous environment. Their non-toxicity was confirmed on primary human dermal fibroblasts. Moreover, we visualized the nanoparticles by 19F MRI, both in vitro (in aqueous phantoms) and in vivo (after subcutaneous injection in mice), thus confirming their biomedical potential.

Automated summary

A straightforward synthetic route to highly fluorinated 19F MRI nanotracers was reported, using water-soluble fluorinated monomers and polymerization-induced self-assembly. The resulting nanoparticles exhibited strong 19F NMR/MRI signals in an aqueous environment and were confirmed to be non-toxic.