Heteroditopic Binding of Magnetic Resonance Contrast Agents for Increased Relaxivity

Kept within bounds: For peptide‐targeted contrast agents, internal motion limits the relaxivity gain. A focused library approach identified an N‐terminal thymine peptide nucleic acid (PNA) that reaches an additional binding pocket on the protein fibrin. The heteroditopic binding rigidifies the molecule upon binding, resulting in increased protein‐bound relaxivity (see picture).