Hyperbranched Polymeric 19 F MRI Contrast Agents with Long T 2 Relaxation Time Based on β-Cyclodextrin and Phosphorycholine.

19 F magnetic resonance imaging ( 19 F MRI) is gaining attention as an emerging diagnostic technology. Effective 19 F MRI contrast agents (CAs) for in vivo applications require a long transverse (or spin-spin) relaxation time ( T 2 ), short longitudinal (or spin-lattice) relaxation time ( T 1 ), high fluorine content, and excellent biocompatibility. Here, we present a novel hyperbranched polymeric 19 F MRI CA based on β-cyclodextrin and phosphorylcholine. The influence of the branching degree and fluorine content on T 2 was thoroughly investigated. Results demonstrated a maximum fluorine content of 11.85% and a T 2 of 612 ms. This hyperbranched polymeric 19 F MRI CA exhibited both great biocompatibility against cells and organs of mice and high-performance imaging capabilities both in vitro and in vivo. The research provides positive insights into the synthesis strategies, topological design, and selection of fluorine tags for 19 F MRI CAs.