Zwitterionic Fluorinated Phosphocholine Block Copolymer Nanoparticles with Aggregation-Induced Emission for Dual-Modality 19F MRI/Fluorescence Bioimaging.

Abstract

Fluorine-19 magnetic resonance imaging (19F MRI) offers low-background, concentration-responsive imaging but suffers from low sensitivity and short transverse relaxation times. Aggregation-induced emission (AIE) fluorophores provide complementary optical imaging through strong fluorescence upon aggregation. Here, fluorinated amphiphilic block copolymers were prepared by reversible addition-fragmentation chain-transfer (RAFT) polymerization of dimethylaminoethyl methacrylate (DMAEMA) and tetraphenylethylene acrylate (TPEA), followed by phosphocholine fluorination. The resulting PTPE-PFCP nanoparticles self-assembled into core-shell structures with a hydrophobic AIE-active PTPE core and a hydrophilic fluorinated phosphocholine corona. The optimized nanoparticles showed well-resolved 19F signals, with T1 and T2 values of 0.222 and 0.184 s, respectively, and gave readily detectable 19F MRI signals. Fluorescence increased over 6 h, while cell viability remained above 70% at 100 μM, with time-dependent cellular fluorescence consistent with nanoparticle uptake. This work presents a feasible strategy for fluorinated AIE-active copolymers as dual-mode 19F MRI/fluorescence imaging probes.

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