A Fluorinated Ionic Liquid-Based Activatable 19F MRI Platform Detects Biological Targets

19F magnetic resonance imaging (19F MRI) is a promising technique for in vivo molecular imaging and clinical diagnosis, benefiting from its negligible background and unlimited tissue penetration depth. However, the development of 19F probes with good water solubility and versatile functions for bioresponsive and practical applications remains a challenge. Here, we report fluorinated ion liquids (ILs) as a new type of fluorine agents and build a fluorinated ionic liquid-based activatable 19F MRI platform (FILAMP), which relies on the phase transition of ILs. Upon exposure to environmental stimulation, coating polymer dissolves or degrades to release the fluorinated ILs payload, which rapidly enhances 19F signal. This turn-on response is verified by the successful detection of biological targets (for example, dysregulated pH and MMP overexpression) at the cellular level and in mice, demonstrating the potential of FILAMP as a robust activatable 19F probe for diagnosis and monitoring of biological and pathological processes.