Design and Characterization of Dual‐Modal Fluorinated BODIPY Probes

Multimodal imaging can improve the detection of molecular and pathophysiological changes by combining complementary readouts within a single probe. Here we report the synthesis and characterization of a fluorinated BODIPY dye (F54-BODIPY) designed as dual fluorescence/19F-MRI imaging agent. The molecular design replaces the native BF2 unit with multibranched perfluoro-tert-butoxy chains appended at the boron atom via B-O hexyloxy linkages, providing 54 magnetically equivalent 19F nuclei per molecule. Additionally, 2,6-dimethylphenyl groups are introduced at 2,6-positions of F54-BODIPY, and (E)-4-methylstyryl residues at the 3,5-positions extend emission into the far-red region of visible spectrum. This probe was structurally characterized by NMR spectroscopy, and its photophysical properties were evaluated by UV–Vis absorption, fluorescence spectroscopy, and fluorescence quantum yield (Φf) measurements. Subsequently F54-BODIPY was encapsulated in poly(lactic-co-glycolic acid) (PLGA) nanoparticles (NPs) for dispersion in aqueous media. Co-encapsulation of a second fluorinated phase, namely perfluoro-15-crown-5 ether (PFCE), significantly modified fluorescence properties and introduced a second 19F-NMR signal, yielding a bimodal nanosystem with dual 19F-NMR signals and red fluorescence emission for combined fluorescence/19F-MRI bioimaging.