Fluoropolymer-Gadolinium(III) Hybrids for Photoactivatable Dual-Mode T1-Weighted 1H MRI and 19F MRI Contrast Agents.

ABSTRACT

Multimodal imaging probes play a crucial role in overcoming the limitations associated with single-mode imaging for clinical medical diagnosis. This study focuses on the development of a photoresponsive fluorine-containing water-soluble polymer (PF) through RAFT polymerization. Subsequently, a polymer-gadolinium(III) hybrid (PF-Gd) dual-modal probe capable of T1-weighted 1H MRI and 19F MRI was synthesized via postmodification of PF with a Gd-DOTA derivative. Under physiological conditions (pH = 7.4), the hybrids exhibit UV-activated 19F NMR/MRI and enhanced 1H MRI. The inclusion of Gd3+ facilitates the acceleration of water molecule T1 relaxation, leading to high-intensity 1H MRI contrast. Leveraging the paramagnetic relaxation enhancement (PRE) effect between fluorine atoms and Gd3+, the restoration of Gd3+-accelerated 19F T2 relaxation enables precise photoactivation of 19F MRI signals, transitioning from the "OFF" to the "ON" state. This study provides an important reference for the development of hybrid systems that function as real-time diagnostic tools and offers controlled activation for multimodal imaging probes.