UV-Activated Zwitterionic Fluorine-Containing Hybrid Probe for Dual-Modal ¹⁹F/¹H MRI

Dual-modal ¹⁹F/¹H MRI probes often suffer from hydrophobic aggregation caused by high fluorine content, limiting their solubility and imaging performance. Herein, a water-soluble dual-modal probe (PFCP-Gd) was developed by grafting fluorinated phosphocholine zwitterions and Gd³⁺ chelates onto a UV-responsive polymer via RAFT polymerization and ring-opening reactions. The design enables UV-triggered paramagnetic relaxation enhancement (PRE) modulation, allowing for activatable ¹⁹F/¹H MRI contrast. Upon UV irradiation, PFCP-Gd exhibited a significantly enhanced ¹⁹F signal with a T₂ relaxation time of 23 ms and a signal-to-noise ratio of 11.34 at 12 mM ¹⁹F. The probe also showed good biocompatibility and an efficient cellular uptake. This work provides a strategy for constructing water-soluble, activatable fluorinated MRI probes for dual-mode imaging.