Activatable ¹⁹F MRI Nanoprobes for Visualization of Biological Targets in Living Subjects

Abstract Visualization of biological targets such as crucial cells and biomolecules in living subjects is critical for the studies of important biological processes. Though ¹H magnetic resonance imaging (MRI) has demonstrated its power in offering detailed anatomical and pathological information, its capacity for in vivo tracking of biological targets is limited by the high biological background of ¹H. ¹⁹F distinguishes itself from its competitors as an exceptional complement to ¹H in MRI through its high sensitivity, low biological background, and broad chemical shift range. The specificity and sensitivity of ¹⁹F MRI can be further boosted with activatable nanoprobes. The advantages of ¹⁹F MRI with activatable nanoprobes enable in vivo detection and imaging at the cellular or even molecular level in deep tissues, rendering this technique appealing as a potential solution for visualization of biological targets in living subjects. Here, recent progress over the past decades on activatable ¹⁹F MRI nanoprobes made from three major ¹⁹F‐containing compounds, as well as present challenges and potential opportunities, are summarized to provide a panoramic prospective for the people who are interested in this emerging and exciting field.