Synthesis and Evaluation of Water‐Soluble Fluorinated Dendritic Block‐Copolymer Nanoparticles as a 19 F‐MRI Contrast Agent

Well‐defined water‐soluble fluorinated polymer nanoparticles (PNPs) with a high fluorine content and biocompatibility were successfully prepared by living radical polymerization (LRP) of 2,2,3,3‐tetrafluoropropyl methacrylate (TFPMA) from the polyamidoamine dendrimer macroinitiator (PAMAM‐Br), and successive block polymerization of carboxybetaine monomer (CMB). The obtained core–shell type PNPs (PAMAM‐ g ‐PTFPMA‐ b ‐PCMB) showed high solubility in water and a sphere‐like structure with a diameter in the range of 15–80 nm in water. The short 19 F‐NMR spin–lattice relaxation time ( T 1 ) (<250 ms) of PAMAM‐ g ‐PTFPMA‐ b ‐PCMB allowed the use of fast repetition time. The spin–spin relaxation time ( T 2 ) was evaluated to be as low as 10 ms. 19 F‐MRI in vitro signals can be detectable even at concentrations lower than 1 µ M (particle concentration). These results demonstrate that a new type of 19 F‐MRI contrast agent can be developed by the molecular design using the dendrimer‐initiated LRP method. magnified image