19F magnetic resonance imaging (MRI) is a powerful noninvasive molecular imaging technique for the detection of important diseases. The major challenge of 19F MRI is signal attenuation caused by the reduced mobility of probes with increased fluorine content. Here we report the synthesis of perfluoropolyether (PFPE) end-functionalised homopolymer of oligo(ethylene glycol) methyl ether acrylate (poly(OEGA)m-PFPE) for the development of highly sensitive 19F MRI contrast agents (CAs). The structural characteristics, conformation/aggregation behaviour, 19F NMR/MRI properties were studied in detail. Dynamic light scattering and molecular dynamics simulations were conducted and demonstrated that the poly(OEGA)20-PFPE polymer undergoes single-chain folding in water while polymers with less OEGA content experience multiple-chain aggregation. Long 19F T2 relaxation times were obtained (&gt; 85 ms) and no obvious decrease was observed with increasing fluorine content up to ~30 wt %. Moreover, the signal-to-noise ratio increases linearly with increasing concentration of fluorine. In a comparative study, partly-fluorinated statistical copolymers containing trifluoroethyl acrylate (TFEA) were also prepared. The 19F T2 of the TFEA-based polymers dropped dramatically with an increase in fluorine content. Cell uptake and NMR performance within the cells was also examined, showing robust uptake of all PFPE-based polymers and high in-cell mobility of fluorinated polymer segments. To date, this is the first report of the synthesis of polymeric PFPE-based CAs and our results show that the PFPE-based polymers are an exciting new class of 19F MRI CAs with extremely high fluorine content and outstanding sensitivity.

PFPE-based polymeric 19F MRI agents: A new class of contrast agents with outstanding sensitivity

253rd National Meeting (2017)

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