9F MR imaging probe for furin detection in vitro and in living cells

The 9F magnetic resonance imaging (MRI) probe 1, CBT-Lys(FMBA)-Cys(StBu)-Arg-Arg-Val-Arg-Ac, was designed and synthesized. The probe can be reduced by GSH and cleaved by furin which is upregulated in several cancers to yield active intermediate. The 1,2-aminothiol group and cyano group of the intermediate condense quickly to yield the dimer which self-assembles into nanoparticles at or near the locations of furin in cells, inducing a clear turn-off of its 9F NMR signal. The nanoparticles were characterized by scanning electron microscope (SEM), transmission electron microscope (TEM), high performance liquid chromatography (HPLC). Furthermore, results of cell uptake indicate that probe 1 can be easily uptaken by tumor cells resulting in 9F NMR signal “off” for the detection of furin activity inside cells. The proposed 9F NMR probe could be potentially applied to 9F MRI in the future.