¹⁹F MRI-fluorescence imaging dual-modal cell tracking with partially fluorinated nanoemulsions

As a noninvasive "hot-spot" imaging technology, fluorine-19 magnetic resonance imaging (¹⁹F MRI) has been extensively used in cell tracking. However, the peculiar physicochemical properties of perfluorocarbons (PFCs), the most commonly used ¹⁹F MRI agents, sometimes cause low sensitivity, poor cell uptake, and misleading results. In this study, a partially fluorinated agent, perfluoro-tert-butyl benzyl ether, was used to formulate a ¹⁹F MRI-fluorescence imaging (FLI) dual-modal nanoemulsion for cell tracking. Compared with PFCs, the partially fluorinated agent showed considerably improved physicochemical properties, such as lower density, shorter longitudinal relaxation times, and higher solubility to fluorophores, while maintaining high ¹⁹F MRI sensitivity. After being formulated into stable, monodisperse, and paramagnetic Fe³⁺-promoted nanoemulsions, the partially fluorinated agent was used in ¹⁹F MRI-FLI dual imaging tracking of lung cancer A549 cells and macrophages in an inflammation mouse model.