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 T 1 -weighted 1 H MRI and 19 F MRI was synthesized via postmodification of PF with a Gd-DOTA derivative. Under physiological conditions (pH = 7.4), the hybrids exhibit UVactivated 19 F NMR/MRI and enhanced 1 H MRI. The inclusion of Gd 3+ facilitates the acceleration of water molecule T 1 relaxation, leading to highintensity 1 H MRI contrast. Leveraging the paramagnetic relaxation enhancement (PRE) effect between fluorine atoms and Gd 3+ , the restoration of Gd 3+ -accelerated 19 F T 2 relaxation enables precise photoactivation of 19 F 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.